diff options
Diffstat (limited to 'fs/autofs')
| -rw-r--r-- | fs/autofs/Kconfig | 32 | ||||
| -rw-r--r-- | fs/autofs/Makefile | 8 | ||||
| -rw-r--r-- | fs/autofs/autofs_i.h | 279 | ||||
| -rw-r--r-- | fs/autofs/dev-ioctl.c | 741 | ||||
| -rw-r--r-- | fs/autofs/expire.c | 620 | ||||
| -rw-r--r-- | fs/autofs/init.c | 46 | ||||
| -rw-r--r-- | fs/autofs/inode.c | 386 | ||||
| -rw-r--r-- | fs/autofs/root.c | 928 | ||||
| -rw-r--r-- | fs/autofs/symlink.c | 26 | ||||
| -rw-r--r-- | fs/autofs/waitq.c | 513 |
10 files changed, 3579 insertions, 0 deletions
diff --git a/fs/autofs/Kconfig b/fs/autofs/Kconfig new file mode 100644 index 000000000..3b3a6b142 --- /dev/null +++ b/fs/autofs/Kconfig @@ -0,0 +1,32 @@ +# SPDX-License-Identifier: GPL-2.0-only +config AUTOFS4_FS + tristate "Old Kconfig name for Kernel automounter support" + select AUTOFS_FS + help + This name exists for people to just automatically pick up the + new name of the autofs Kconfig option. All it does is select + the new option name. + + It will go away in a release or two as people have + transitioned to just plain AUTOFS_FS. + +config AUTOFS_FS + tristate "Kernel automounter support (supports v3, v4 and v5)" + default n + help + The automounter is a tool to automatically mount remote file systems + on demand. This implementation is partially kernel-based to reduce + overhead in the already-mounted case; this is unlike the BSD + automounter (amd), which is a pure user space daemon. + + To use the automounter you need the user-space tools from + <https://www.kernel.org/pub/linux/daemons/autofs/>; you also want + to answer Y to "NFS file system support", below. + + To compile this support as a module, choose M here: the module will be + called autofs. + + If you are not a part of a fairly large, distributed network or + don't have a laptop which needs to dynamically reconfigure to the + local network, you probably do not need an automounter, and can say + N here. diff --git a/fs/autofs/Makefile b/fs/autofs/Makefile new file mode 100644 index 000000000..495ac542e --- /dev/null +++ b/fs/autofs/Makefile @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# Makefile for the linux autofs-filesystem routines. +# + +obj-$(CONFIG_AUTOFS_FS) += autofs4.o + +autofs4-objs := init.o inode.o root.o symlink.o waitq.o expire.o dev-ioctl.o diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h new file mode 100644 index 000000000..d5a44fa88 --- /dev/null +++ b/fs/autofs/autofs_i.h @@ -0,0 +1,279 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright 1997-1998 Transmeta Corporation - All Rights Reserved + * Copyright 2005-2006 Ian Kent <raven@themaw.net> + */ + +/* Internal header file for autofs */ + +#include <linux/auto_fs.h> +#include <linux/auto_dev-ioctl.h> + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/time.h> +#include <linux/string.h> +#include <linux/wait.h> +#include <linux/sched.h> +#include <linux/sched/signal.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/uaccess.h> +#include <linux/mutex.h> +#include <linux/spinlock.h> +#include <linux/list.h> +#include <linux/completion.h> +#include <linux/file.h> +#include <linux/magic.h> + +/* This is the range of ioctl() numbers we claim as ours */ +#define AUTOFS_IOC_FIRST AUTOFS_IOC_READY +#define AUTOFS_IOC_COUNT 32 + +#define AUTOFS_DEV_IOCTL_IOC_FIRST (AUTOFS_DEV_IOCTL_VERSION) +#define AUTOFS_DEV_IOCTL_IOC_COUNT \ + (AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD - AUTOFS_DEV_IOCTL_VERSION_CMD) + +#ifdef pr_fmt +#undef pr_fmt +#endif +#define pr_fmt(fmt) KBUILD_MODNAME ":pid:%d:%s: " fmt, current->pid, __func__ + +extern struct file_system_type autofs_fs_type; + +/* + * Unified info structure. This is pointed to by both the dentry and + * inode structures. Each file in the filesystem has an instance of this + * structure. It holds a reference to the dentry, so dentries are never + * flushed while the file exists. All name lookups are dealt with at the + * dentry level, although the filesystem can interfere in the validation + * process. Readdir is implemented by traversing the dentry lists. + */ +struct autofs_info { + struct dentry *dentry; + int flags; + + struct completion expire_complete; + + struct list_head active; + + struct list_head expiring; + + struct autofs_sb_info *sbi; + unsigned long last_used; + int count; + + kuid_t uid; + kgid_t gid; + struct rcu_head rcu; +}; + +#define AUTOFS_INF_EXPIRING (1<<0) /* dentry in the process of expiring */ +#define AUTOFS_INF_WANT_EXPIRE (1<<1) /* the dentry is being considered + * for expiry, so RCU_walk is + * not permitted. If it progresses to + * actual expiry attempt, the flag is + * not cleared when EXPIRING is set - + * in that case it gets cleared only + * when it comes to clearing EXPIRING. + */ +#define AUTOFS_INF_PENDING (1<<2) /* dentry pending mount */ + +struct autofs_wait_queue { + wait_queue_head_t queue; + struct autofs_wait_queue *next; + autofs_wqt_t wait_queue_token; + /* We use the following to see what we are waiting for */ + struct qstr name; + u32 offset; + u32 dev; + u64 ino; + kuid_t uid; + kgid_t gid; + pid_t pid; + pid_t tgid; + /* This is for status reporting upon return */ + int status; + unsigned int wait_ctr; +}; + +#define AUTOFS_SBI_MAGIC 0x6d4a556d + +#define AUTOFS_SBI_CATATONIC 0x0001 +#define AUTOFS_SBI_STRICTEXPIRE 0x0002 +#define AUTOFS_SBI_IGNORE 0x0004 + +struct autofs_sb_info { + u32 magic; + int pipefd; + struct file *pipe; + struct pid *oz_pgrp; + int version; + int sub_version; + int min_proto; + int max_proto; + unsigned int flags; + unsigned long exp_timeout; + unsigned int type; + struct super_block *sb; + struct mutex wq_mutex; + struct mutex pipe_mutex; + spinlock_t fs_lock; + struct autofs_wait_queue *queues; /* Wait queue pointer */ + spinlock_t lookup_lock; + struct list_head active_list; + struct list_head expiring_list; + struct rcu_head rcu; +}; + +static inline struct autofs_sb_info *autofs_sbi(struct super_block *sb) +{ + return (struct autofs_sb_info *)(sb->s_fs_info); +} + +static inline struct autofs_info *autofs_dentry_ino(struct dentry *dentry) +{ + return (struct autofs_info *)(dentry->d_fsdata); +} + +/* autofs_oz_mode(): do we see the man behind the curtain? (The + * processes which do manipulations for us in user space sees the raw + * filesystem without "magic".) + */ +static inline int autofs_oz_mode(struct autofs_sb_info *sbi) +{ + return ((sbi->flags & AUTOFS_SBI_CATATONIC) || + task_pgrp(current) == sbi->oz_pgrp); +} + +static inline bool autofs_empty(struct autofs_info *ino) +{ + return ino->count < 2; +} + +struct inode *autofs_get_inode(struct super_block *, umode_t); +void autofs_free_ino(struct autofs_info *); + +/* Expiration */ +int is_autofs_dentry(struct dentry *); +int autofs_expire_wait(const struct path *path, int rcu_walk); +int autofs_expire_run(struct super_block *, struct vfsmount *, + struct autofs_sb_info *, + struct autofs_packet_expire __user *); +int autofs_do_expire_multi(struct super_block *sb, struct vfsmount *mnt, + struct autofs_sb_info *sbi, unsigned int how); +int autofs_expire_multi(struct super_block *, struct vfsmount *, + struct autofs_sb_info *, int __user *); + +/* Device node initialization */ + +int autofs_dev_ioctl_init(void); +void autofs_dev_ioctl_exit(void); + +/* Operations structures */ + +extern const struct inode_operations autofs_symlink_inode_operations; +extern const struct inode_operations autofs_dir_inode_operations; +extern const struct file_operations autofs_dir_operations; +extern const struct file_operations autofs_root_operations; +extern const struct dentry_operations autofs_dentry_operations; + +/* VFS automount flags management functions */ +static inline void __managed_dentry_set_managed(struct dentry *dentry) +{ + dentry->d_flags |= (DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT); +} + +static inline void managed_dentry_set_managed(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + __managed_dentry_set_managed(dentry); + spin_unlock(&dentry->d_lock); +} + +static inline void __managed_dentry_clear_managed(struct dentry *dentry) +{ + dentry->d_flags &= ~(DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT); +} + +static inline void managed_dentry_clear_managed(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + __managed_dentry_clear_managed(dentry); + spin_unlock(&dentry->d_lock); +} + +/* Initializing function */ + +int autofs_fill_super(struct super_block *, void *, int); +struct autofs_info *autofs_new_ino(struct autofs_sb_info *); +void autofs_clean_ino(struct autofs_info *); + +static inline int autofs_prepare_pipe(struct file *pipe) +{ + if (!(pipe->f_mode & FMODE_CAN_WRITE)) + return -EINVAL; + if (!S_ISFIFO(file_inode(pipe)->i_mode)) + return -EINVAL; + /* We want a packet pipe */ + pipe->f_flags |= O_DIRECT; + /* We don't expect -EAGAIN */ + pipe->f_flags &= ~O_NONBLOCK; + return 0; +} + +/* Queue management functions */ + +int autofs_wait(struct autofs_sb_info *, + const struct path *, enum autofs_notify); +int autofs_wait_release(struct autofs_sb_info *, autofs_wqt_t, int); +void autofs_catatonic_mode(struct autofs_sb_info *); + +static inline u32 autofs_get_dev(struct autofs_sb_info *sbi) +{ + return new_encode_dev(sbi->sb->s_dev); +} + +static inline u64 autofs_get_ino(struct autofs_sb_info *sbi) +{ + return d_inode(sbi->sb->s_root)->i_ino; +} + +static inline void __autofs_add_expiring(struct dentry *dentry) +{ + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + + if (ino) { + if (list_empty(&ino->expiring)) + list_add(&ino->expiring, &sbi->expiring_list); + } +} + +static inline void autofs_add_expiring(struct dentry *dentry) +{ + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + + if (ino) { + spin_lock(&sbi->lookup_lock); + if (list_empty(&ino->expiring)) + list_add(&ino->expiring, &sbi->expiring_list); + spin_unlock(&sbi->lookup_lock); + } +} + +static inline void autofs_del_expiring(struct dentry *dentry) +{ + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + + if (ino) { + spin_lock(&sbi->lookup_lock); + if (!list_empty(&ino->expiring)) + list_del_init(&ino->expiring); + spin_unlock(&sbi->lookup_lock); + } +} + +void autofs_kill_sb(struct super_block *); diff --git a/fs/autofs/dev-ioctl.c b/fs/autofs/dev-ioctl.c new file mode 100644 index 000000000..5bf781ea6 --- /dev/null +++ b/fs/autofs/dev-ioctl.c @@ -0,0 +1,741 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 2008 Red Hat, Inc. All rights reserved. + * Copyright 2008 Ian Kent <raven@themaw.net> + */ + +#include <linux/module.h> +#include <linux/miscdevice.h> +#include <linux/compat.h> +#include <linux/fdtable.h> +#include <linux/magic.h> +#include <linux/nospec.h> + +#include "autofs_i.h" + +/* + * This module implements an interface for routing autofs ioctl control + * commands via a miscellaneous device file. + * + * The alternate interface is needed because we need to be able open + * an ioctl file descriptor on an autofs mount that may be covered by + * another mount. This situation arises when starting automount(8) + * or other user space daemon which uses direct mounts or offset + * mounts (used for autofs lazy mount/umount of nested mount trees), + * which have been left busy at service shutdown. + */ + +typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *, + struct autofs_dev_ioctl *); + +static int check_name(const char *name) +{ + if (!strchr(name, '/')) + return -EINVAL; + return 0; +} + +/* + * Check a string doesn't overrun the chunk of + * memory we copied from user land. + */ +static int invalid_str(char *str, size_t size) +{ + if (memchr(str, 0, size)) + return 0; + return -EINVAL; +} + +/* + * Check that the user compiled against correct version of autofs + * misc device code. + * + * As well as checking the version compatibility this always copies + * the kernel interface version out. + */ +static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param) +{ + int err = 0; + + if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) || + (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) { + pr_warn("ioctl control interface version mismatch: " + "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n", + AUTOFS_DEV_IOCTL_VERSION_MAJOR, + AUTOFS_DEV_IOCTL_VERSION_MINOR, + param->ver_major, param->ver_minor, cmd); + err = -EINVAL; + } + + /* Fill in the kernel version. */ + param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR; + param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR; + + return err; +} + +/* + * Copy parameter control struct, including a possible path allocated + * at the end of the struct. + */ +static struct autofs_dev_ioctl * +copy_dev_ioctl(struct autofs_dev_ioctl __user *in) +{ + struct autofs_dev_ioctl tmp, *res; + + if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE)) + return ERR_PTR(-EFAULT); + + if (tmp.size < AUTOFS_DEV_IOCTL_SIZE) + return ERR_PTR(-EINVAL); + + if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX) + return ERR_PTR(-ENAMETOOLONG); + + res = memdup_user(in, tmp.size); + if (!IS_ERR(res)) + res->size = tmp.size; + + return res; +} + +static inline void free_dev_ioctl(struct autofs_dev_ioctl *param) +{ + kfree(param); +} + +/* + * Check sanity of parameter control fields and if a path is present + * check that it is terminated and contains at least one "/". + */ +static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param) +{ + int err; + + err = check_dev_ioctl_version(cmd, param); + if (err) { + pr_warn("invalid device control module version " + "supplied for cmd(0x%08x)\n", cmd); + goto out; + } + + if (param->size > AUTOFS_DEV_IOCTL_SIZE) { + err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE); + if (err) { + pr_warn( + "path string terminator missing for cmd(0x%08x)\n", + cmd); + goto out; + } + + err = check_name(param->path); + if (err) { + pr_warn("invalid path supplied for cmd(0x%08x)\n", + cmd); + goto out; + } + } else { + unsigned int inr = _IOC_NR(cmd); + + if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD || + inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD || + inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) { + err = -EINVAL; + goto out; + } + } + + err = 0; +out: + return err; +} + +/* Return autofs dev ioctl version */ +static int autofs_dev_ioctl_version(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + /* This should have already been set. */ + param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR; + param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR; + return 0; +} + +/* Return autofs module protocol version */ +static int autofs_dev_ioctl_protover(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + param->protover.version = sbi->version; + return 0; +} + +/* Return autofs module protocol sub version */ +static int autofs_dev_ioctl_protosubver(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + param->protosubver.sub_version = sbi->sub_version; + return 0; +} + +/* Find the topmost mount satisfying test() */ +static int find_autofs_mount(const char *pathname, + struct path *res, + int test(const struct path *path, void *data), + void *data) +{ + struct path path; + int err; + + err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path); + if (err) + return err; + err = -ENOENT; + while (path.dentry == path.mnt->mnt_root) { + if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) { + if (test(&path, data)) { + path_get(&path); + *res = path; + err = 0; + break; + } + } + if (!follow_up(&path)) + break; + } + path_put(&path); + return err; +} + +static int test_by_dev(const struct path *path, void *p) +{ + return path->dentry->d_sb->s_dev == *(dev_t *)p; +} + +static int test_by_type(const struct path *path, void *p) +{ + struct autofs_info *ino = autofs_dentry_ino(path->dentry); + + return ino && ino->sbi->type & *(unsigned *)p; +} + +/* + * Open a file descriptor on the autofs mount point corresponding + * to the given path and device number (aka. new_encode_dev(sb->s_dev)). + */ +static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid) +{ + int err, fd; + + fd = get_unused_fd_flags(O_CLOEXEC); + if (likely(fd >= 0)) { + struct file *filp; + struct path path; + + err = find_autofs_mount(name, &path, test_by_dev, &devid); + if (err) + goto out; + + filp = dentry_open(&path, O_RDONLY, current_cred()); + path_put(&path); + if (IS_ERR(filp)) { + err = PTR_ERR(filp); + goto out; + } + + fd_install(fd, filp); + } + + return fd; + +out: + put_unused_fd(fd); + return err; +} + +/* Open a file descriptor on an autofs mount point */ +static int autofs_dev_ioctl_openmount(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + const char *path; + dev_t devid; + int err, fd; + + /* param->path has been checked in validate_dev_ioctl() */ + + if (!param->openmount.devid) + return -EINVAL; + + param->ioctlfd = -1; + + path = param->path; + devid = new_decode_dev(param->openmount.devid); + + err = 0; + fd = autofs_dev_ioctl_open_mountpoint(path, devid); + if (unlikely(fd < 0)) { + err = fd; + goto out; + } + + param->ioctlfd = fd; +out: + return err; +} + +/* Close file descriptor allocated above (user can also use close(2)). */ +static int autofs_dev_ioctl_closemount(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + return close_fd(param->ioctlfd); +} + +/* + * Send "ready" status for an existing wait (either a mount or an expire + * request). + */ +static int autofs_dev_ioctl_ready(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + autofs_wqt_t token; + + token = (autofs_wqt_t) param->ready.token; + return autofs_wait_release(sbi, token, 0); +} + +/* + * Send "fail" status for an existing wait (either a mount or an expire + * request). + */ +static int autofs_dev_ioctl_fail(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + autofs_wqt_t token; + int status; + + token = (autofs_wqt_t) param->fail.token; + status = param->fail.status < 0 ? param->fail.status : -ENOENT; + return autofs_wait_release(sbi, token, status); +} + +/* + * Set the pipe fd for kernel communication to the daemon. + * + * Normally this is set at mount using an option but if we + * are reconnecting to a busy mount then we need to use this + * to tell the autofs mount about the new kernel pipe fd. In + * order to protect mounts against incorrectly setting the + * pipefd we also require that the autofs mount be catatonic. + * + * This also sets the process group id used to identify the + * controlling process (eg. the owning automount(8) daemon). + */ +static int autofs_dev_ioctl_setpipefd(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + int pipefd; + int err = 0; + struct pid *new_pid = NULL; + + if (param->setpipefd.pipefd == -1) + return -EINVAL; + + pipefd = param->setpipefd.pipefd; + + mutex_lock(&sbi->wq_mutex); + if (!(sbi->flags & AUTOFS_SBI_CATATONIC)) { + mutex_unlock(&sbi->wq_mutex); + return -EBUSY; + } else { + struct file *pipe; + + new_pid = get_task_pid(current, PIDTYPE_PGID); + + if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) { + pr_warn("not allowed to change PID namespace\n"); + err = -EINVAL; + goto out; + } + + pipe = fget(pipefd); + if (!pipe) { + err = -EBADF; + goto out; + } + if (autofs_prepare_pipe(pipe) < 0) { + err = -EPIPE; + fput(pipe); + goto out; + } + swap(sbi->oz_pgrp, new_pid); + sbi->pipefd = pipefd; + sbi->pipe = pipe; + sbi->flags &= ~AUTOFS_SBI_CATATONIC; + } +out: + put_pid(new_pid); + mutex_unlock(&sbi->wq_mutex); + return err; +} + +/* + * Make the autofs mount point catatonic, no longer responsive to + * mount requests. Also closes the kernel pipe file descriptor. + */ +static int autofs_dev_ioctl_catatonic(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + autofs_catatonic_mode(sbi); + return 0; +} + +/* Set the autofs mount timeout */ +static int autofs_dev_ioctl_timeout(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + unsigned long timeout; + + timeout = param->timeout.timeout; + param->timeout.timeout = sbi->exp_timeout / HZ; + sbi->exp_timeout = timeout * HZ; + return 0; +} + +/* + * Return the uid and gid of the last request for the mount + * + * When reconstructing an autofs mount tree with active mounts + * we need to re-connect to mounts that may have used the original + * process uid and gid (or string variations of them) for mount + * lookups within the map entry. + */ +static int autofs_dev_ioctl_requester(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + struct autofs_info *ino; + struct path path; + dev_t devid; + int err = -ENOENT; + + /* param->path has been checked in validate_dev_ioctl() */ + + devid = sbi->sb->s_dev; + + param->requester.uid = param->requester.gid = -1; + + err = find_autofs_mount(param->path, &path, test_by_dev, &devid); + if (err) + goto out; + + ino = autofs_dentry_ino(path.dentry); + if (ino) { + err = 0; + autofs_expire_wait(&path, 0); + spin_lock(&sbi->fs_lock); + param->requester.uid = + from_kuid_munged(current_user_ns(), ino->uid); + param->requester.gid = + from_kgid_munged(current_user_ns(), ino->gid); + spin_unlock(&sbi->fs_lock); + } + path_put(&path); +out: + return err; +} + +/* + * Call repeatedly until it returns -EAGAIN, meaning there's nothing + * more that can be done. + */ +static int autofs_dev_ioctl_expire(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + struct vfsmount *mnt; + int how; + + how = param->expire.how; + mnt = fp->f_path.mnt; + + return autofs_do_expire_multi(sbi->sb, mnt, sbi, how); +} + +/* Check if autofs mount point is in use */ +static int autofs_dev_ioctl_askumount(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + param->askumount.may_umount = 0; + if (may_umount(fp->f_path.mnt)) + param->askumount.may_umount = 1; + return 0; +} + +/* + * Check if the given path is a mountpoint. + * + * If we are supplied with the file descriptor of an autofs + * mount we're looking for a specific mount. In this case + * the path is considered a mountpoint if it is itself a + * mountpoint or contains a mount, such as a multi-mount + * without a root mount. In this case we return 1 if the + * path is a mount point and the super magic of the covering + * mount if there is one or 0 if it isn't a mountpoint. + * + * If we aren't supplied with a file descriptor then we + * lookup the path and check if it is the root of a mount. + * If a type is given we are looking for a particular autofs + * mount and if we don't find a match we return fail. If the + * located path is the root of a mount we return 1 along with + * the super magic of the mount or 0 otherwise. + * + * In both cases the device number (as returned by + * new_encode_dev()) is also returned. + */ +static int autofs_dev_ioctl_ismountpoint(struct file *fp, + struct autofs_sb_info *sbi, + struct autofs_dev_ioctl *param) +{ + struct path path; + const char *name; + unsigned int type; + unsigned int devid, magic; + int err = -ENOENT; + + /* param->path has been checked in validate_dev_ioctl() */ + + name = param->path; + type = param->ismountpoint.in.type; + + param->ismountpoint.out.devid = devid = 0; + param->ismountpoint.out.magic = magic = 0; + + if (!fp || param->ioctlfd == -1) { + if (autofs_type_any(type)) + err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT, + &path); + else + err = find_autofs_mount(name, &path, + test_by_type, &type); + if (err) + goto out; + devid = new_encode_dev(path.dentry->d_sb->s_dev); + err = 0; + if (path.mnt->mnt_root == path.dentry) { + err = 1; + magic = path.dentry->d_sb->s_magic; + } + } else { + dev_t dev = sbi->sb->s_dev; + + err = find_autofs_mount(name, &path, test_by_dev, &dev); + if (err) + goto out; + + devid = new_encode_dev(dev); + + err = path_has_submounts(&path); + + if (follow_down_one(&path)) + magic = path.dentry->d_sb->s_magic; + } + + param->ismountpoint.out.devid = devid; + param->ismountpoint.out.magic = magic; + path_put(&path); +out: + return err; +} + +/* + * Our range of ioctl numbers isn't 0 based so we need to shift + * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table + * lookup. + */ +#define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST)) + +static ioctl_fn lookup_dev_ioctl(unsigned int cmd) +{ + static const ioctl_fn _ioctls[] = { + autofs_dev_ioctl_version, + autofs_dev_ioctl_protover, + autofs_dev_ioctl_protosubver, + autofs_dev_ioctl_openmount, + autofs_dev_ioctl_closemount, + autofs_dev_ioctl_ready, + autofs_dev_ioctl_fail, + autofs_dev_ioctl_setpipefd, + autofs_dev_ioctl_catatonic, + autofs_dev_ioctl_timeout, + autofs_dev_ioctl_requester, + autofs_dev_ioctl_expire, + autofs_dev_ioctl_askumount, + autofs_dev_ioctl_ismountpoint, + }; + unsigned int idx = cmd_idx(cmd); + + if (idx >= ARRAY_SIZE(_ioctls)) + return NULL; + idx = array_index_nospec(idx, ARRAY_SIZE(_ioctls)); + return _ioctls[idx]; +} + +/* ioctl dispatcher */ +static int _autofs_dev_ioctl(unsigned int command, + struct autofs_dev_ioctl __user *user) +{ + struct autofs_dev_ioctl *param; + struct file *fp; + struct autofs_sb_info *sbi; + unsigned int cmd_first, cmd; + ioctl_fn fn = NULL; + int err = 0; + + cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST); + cmd = _IOC_NR(command); + + if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) || + cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) { + return -ENOTTY; + } + + /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD + * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD + */ + if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD && + cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD && + !capable(CAP_SYS_ADMIN)) + return -EPERM; + + /* Copy the parameters into kernel space. */ + param = copy_dev_ioctl(user); + if (IS_ERR(param)) + return PTR_ERR(param); + + err = validate_dev_ioctl(command, param); + if (err) + goto out; + + fn = lookup_dev_ioctl(cmd); + if (!fn) { + pr_warn("unknown command 0x%08x\n", command); + err = -ENOTTY; + goto out; + } + + fp = NULL; + sbi = NULL; + + /* + * For obvious reasons the openmount can't have a file + * descriptor yet. We don't take a reference to the + * file during close to allow for immediate release, + * and the same for retrieving ioctl version. + */ + if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD && + cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD && + cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) { + struct super_block *sb; + + fp = fget(param->ioctlfd); + if (!fp) { + if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) + goto cont; + err = -EBADF; + goto out; + } + + sb = file_inode(fp)->i_sb; + if (sb->s_type != &autofs_fs_type) { + err = -EINVAL; + fput(fp); + goto out; + } + sbi = autofs_sbi(sb); + + /* + * Admin needs to be able to set the mount catatonic in + * order to be able to perform the re-open. + */ + if (!autofs_oz_mode(sbi) && + cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) { + err = -EACCES; + fput(fp); + goto out; + } + } +cont: + err = fn(fp, sbi, param); + + if (fp) + fput(fp); + if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE)) + err = -EFAULT; +out: + free_dev_ioctl(param); + return err; +} + +static long autofs_dev_ioctl(struct file *file, unsigned int command, + unsigned long u) +{ + int err; + + err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u); + return (long) err; +} + +#ifdef CONFIG_COMPAT +static long autofs_dev_ioctl_compat(struct file *file, unsigned int command, + unsigned long u) +{ + return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u)); +} +#else +#define autofs_dev_ioctl_compat NULL +#endif + +static const struct file_operations _dev_ioctl_fops = { + .unlocked_ioctl = autofs_dev_ioctl, + .compat_ioctl = autofs_dev_ioctl_compat, + .owner = THIS_MODULE, + .llseek = noop_llseek, +}; + +static struct miscdevice _autofs_dev_ioctl_misc = { + .minor = AUTOFS_MINOR, + .name = AUTOFS_DEVICE_NAME, + .fops = &_dev_ioctl_fops, + .mode = 0644, +}; + +MODULE_ALIAS_MISCDEV(AUTOFS_MINOR); +MODULE_ALIAS("devname:autofs"); + +/* Register/deregister misc character device */ +int __init autofs_dev_ioctl_init(void) +{ + int r; + + r = misc_register(&_autofs_dev_ioctl_misc); + if (r) { + pr_err("misc_register failed for control device\n"); + return r; + } + + return 0; +} + +void autofs_dev_ioctl_exit(void) +{ + misc_deregister(&_autofs_dev_ioctl_misc); +} diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c new file mode 100644 index 000000000..038b3d2d9 --- /dev/null +++ b/fs/autofs/expire.c @@ -0,0 +1,620 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved + * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org> + * Copyright 2001-2006 Ian Kent <raven@themaw.net> + */ + +#include "autofs_i.h" + +/* Check if a dentry can be expired */ +static inline int autofs_can_expire(struct dentry *dentry, + unsigned long timeout, unsigned int how) +{ + struct autofs_info *ino = autofs_dentry_ino(dentry); + + /* dentry in the process of being deleted */ + if (ino == NULL) + return 0; + + if (!(how & AUTOFS_EXP_IMMEDIATE)) { + /* Too young to die */ + if (!timeout || time_after(ino->last_used + timeout, jiffies)) + return 0; + } + return 1; +} + +/* Check a mount point for busyness */ +static int autofs_mount_busy(struct vfsmount *mnt, + struct dentry *dentry, unsigned int how) +{ + struct dentry *top = dentry; + struct path path = {.mnt = mnt, .dentry = dentry}; + int status = 1; + + pr_debug("dentry %p %pd\n", dentry, dentry); + + path_get(&path); + + if (!follow_down_one(&path)) + goto done; + + if (is_autofs_dentry(path.dentry)) { + struct autofs_sb_info *sbi = autofs_sbi(path.dentry->d_sb); + + /* This is an autofs submount, we can't expire it */ + if (autofs_type_indirect(sbi->type)) + goto done; + } + + /* Not a submount, has a forced expire been requested */ + if (how & AUTOFS_EXP_FORCED) { + status = 0; + goto done; + } + + /* Update the expiry counter if fs is busy */ + if (!may_umount_tree(path.mnt)) { + struct autofs_info *ino; + + ino = autofs_dentry_ino(top); + ino->last_used = jiffies; + goto done; + } + + status = 0; +done: + pr_debug("returning = %d\n", status); + path_put(&path); + return status; +} + +/* p->d_lock held */ +static struct dentry *positive_after(struct dentry *p, struct dentry *child) +{ + if (child) + child = list_next_entry(child, d_child); + else + child = list_first_entry(&p->d_subdirs, struct dentry, d_child); + + list_for_each_entry_from(child, &p->d_subdirs, d_child) { + spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(child)) { + dget_dlock(child); + spin_unlock(&child->d_lock); + return child; + } + spin_unlock(&child->d_lock); + } + + return NULL; +} + +/* + * Calculate and dget next entry in the subdirs list under root. + */ +static struct dentry *get_next_positive_subdir(struct dentry *prev, + struct dentry *root) +{ + struct autofs_sb_info *sbi = autofs_sbi(root->d_sb); + struct dentry *q; + + spin_lock(&sbi->lookup_lock); + spin_lock(&root->d_lock); + q = positive_after(root, prev); + spin_unlock(&root->d_lock); + spin_unlock(&sbi->lookup_lock); + dput(prev); + return q; +} + +/* + * Calculate and dget next entry in top down tree traversal. + */ +static struct dentry *get_next_positive_dentry(struct dentry *prev, + struct dentry *root) +{ + struct autofs_sb_info *sbi = autofs_sbi(root->d_sb); + struct dentry *p = prev, *ret = NULL, *d = NULL; + + if (prev == NULL) + return dget(root); + + spin_lock(&sbi->lookup_lock); + spin_lock(&p->d_lock); + while (1) { + struct dentry *parent; + + ret = positive_after(p, d); + if (ret || p == root) + break; + parent = p->d_parent; + spin_unlock(&p->d_lock); + spin_lock(&parent->d_lock); + d = p; + p = parent; + } + spin_unlock(&p->d_lock); + spin_unlock(&sbi->lookup_lock); + dput(prev); + return ret; +} + +/* + * Check a direct mount point for busyness. + * Direct mounts have similar expiry semantics to tree mounts. + * The tree is not busy iff no mountpoints are busy and there are no + * autofs submounts. + */ +static int autofs_direct_busy(struct vfsmount *mnt, + struct dentry *top, + unsigned long timeout, + unsigned int how) +{ + pr_debug("top %p %pd\n", top, top); + + /* Forced expire, user space handles busy mounts */ + if (how & AUTOFS_EXP_FORCED) + return 0; + + /* If it's busy update the expiry counters */ + if (!may_umount_tree(mnt)) { + struct autofs_info *ino; + + ino = autofs_dentry_ino(top); + if (ino) + ino->last_used = jiffies; + return 1; + } + + /* Timeout of a direct mount is determined by its top dentry */ + if (!autofs_can_expire(top, timeout, how)) + return 1; + + return 0; +} + +/* + * Check a directory tree of mount points for busyness + * The tree is not busy iff no mountpoints are busy + */ +static int autofs_tree_busy(struct vfsmount *mnt, + struct dentry *top, + unsigned long timeout, + unsigned int how) +{ + struct autofs_info *top_ino = autofs_dentry_ino(top); + struct dentry *p; + + pr_debug("top %p %pd\n", top, top); + + /* Negative dentry - give up */ + if (!simple_positive(top)) + return 1; + + p = NULL; + while ((p = get_next_positive_dentry(p, top))) { + pr_debug("dentry %p %pd\n", p, p); + + /* + * Is someone visiting anywhere in the subtree ? + * If there's no mount we need to check the usage + * count for the autofs dentry. + * If the fs is busy update the expiry counter. + */ + if (d_mountpoint(p)) { + if (autofs_mount_busy(mnt, p, how)) { + top_ino->last_used = jiffies; + dput(p); + return 1; + } + } else { + struct autofs_info *ino = autofs_dentry_ino(p); + unsigned int ino_count = READ_ONCE(ino->count); + + /* allow for dget above and top is already dgot */ + if (p == top) + ino_count += 2; + else + ino_count++; + + if (d_count(p) > ino_count) { + top_ino->last_used = jiffies; + dput(p); + return 1; + } + } + } + + /* Forced expire, user space handles busy mounts */ + if (how & AUTOFS_EXP_FORCED) + return 0; + + /* Timeout of a tree mount is ultimately determined by its top dentry */ + if (!autofs_can_expire(top, timeout, how)) + return 1; + + return 0; +} + +static struct dentry *autofs_check_leaves(struct vfsmount *mnt, + struct dentry *parent, + unsigned long timeout, + unsigned int how) +{ + struct dentry *p; + + pr_debug("parent %p %pd\n", parent, parent); + + p = NULL; + while ((p = get_next_positive_dentry(p, parent))) { + pr_debug("dentry %p %pd\n", p, p); + + if (d_mountpoint(p)) { + /* Can we umount this guy */ + if (autofs_mount_busy(mnt, p, how)) + continue; + + /* This isn't a submount so if a forced expire + * has been requested, user space handles busy + * mounts */ + if (how & AUTOFS_EXP_FORCED) + return p; + + /* Can we expire this guy */ + if (autofs_can_expire(p, timeout, how)) + return p; + } + } + return NULL; +} + +/* Check if we can expire a direct mount (possibly a tree) */ +static struct dentry *autofs_expire_direct(struct super_block *sb, + struct vfsmount *mnt, + struct autofs_sb_info *sbi, + unsigned int how) +{ + struct dentry *root = dget(sb->s_root); + struct autofs_info *ino; + unsigned long timeout; + + if (!root) + return NULL; + + timeout = sbi->exp_timeout; + + if (!autofs_direct_busy(mnt, root, timeout, how)) { + spin_lock(&sbi->fs_lock); + ino = autofs_dentry_ino(root); + /* No point expiring a pending mount */ + if (ino->flags & AUTOFS_INF_PENDING) { + spin_unlock(&sbi->fs_lock); + goto out; + } + ino->flags |= AUTOFS_INF_WANT_EXPIRE; + spin_unlock(&sbi->fs_lock); + synchronize_rcu(); + if (!autofs_direct_busy(mnt, root, timeout, how)) { + spin_lock(&sbi->fs_lock); + ino->flags |= AUTOFS_INF_EXPIRING; + init_completion(&ino->expire_complete); + spin_unlock(&sbi->fs_lock); + return root; + } + spin_lock(&sbi->fs_lock); + ino->flags &= ~AUTOFS_INF_WANT_EXPIRE; + spin_unlock(&sbi->fs_lock); + } +out: + dput(root); + + return NULL; +} + +/* Check if 'dentry' should expire, or return a nearby + * dentry that is suitable. + * If returned dentry is different from arg dentry, + * then a dget() reference was taken, else not. + */ +static struct dentry *should_expire(struct dentry *dentry, + struct vfsmount *mnt, + unsigned long timeout, + unsigned int how) +{ + struct autofs_info *ino = autofs_dentry_ino(dentry); + unsigned int ino_count; + + /* No point expiring a pending mount */ + if (ino->flags & AUTOFS_INF_PENDING) + return NULL; + + /* + * Case 1: (i) indirect mount or top level pseudo direct mount + * (autofs-4.1). + * (ii) indirect mount with offset mount, check the "/" + * offset (autofs-5.0+). + */ + if (d_mountpoint(dentry)) { + pr_debug("checking mountpoint %p %pd\n", dentry, dentry); + + /* Can we umount this guy */ + if (autofs_mount_busy(mnt, dentry, how)) + return NULL; + + /* This isn't a submount so if a forced expire + * has been requested, user space handles busy + * mounts */ + if (how & AUTOFS_EXP_FORCED) + return dentry; + + /* Can we expire this guy */ + if (autofs_can_expire(dentry, timeout, how)) + return dentry; + return NULL; + } + + if (d_is_symlink(dentry)) { + pr_debug("checking symlink %p %pd\n", dentry, dentry); + + /* Forced expire, user space handles busy mounts */ + if (how & AUTOFS_EXP_FORCED) + return dentry; + + /* + * A symlink can't be "busy" in the usual sense so + * just check last used for expire timeout. + */ + if (autofs_can_expire(dentry, timeout, how)) + return dentry; + return NULL; + } + + if (autofs_empty(ino)) + return NULL; + + /* Case 2: tree mount, expire iff entire tree is not busy */ + if (!(how & AUTOFS_EXP_LEAVES)) { + /* Not a forced expire? */ + if (!(how & AUTOFS_EXP_FORCED)) { + /* ref-walk currently on this dentry? */ + ino_count = READ_ONCE(ino->count) + 1; + if (d_count(dentry) > ino_count) + return NULL; + } + + if (!autofs_tree_busy(mnt, dentry, timeout, how)) + return dentry; + /* + * Case 3: pseudo direct mount, expire individual leaves + * (autofs-4.1). + */ + } else { + struct dentry *expired; + + /* Not a forced expire? */ + if (!(how & AUTOFS_EXP_FORCED)) { + /* ref-walk currently on this dentry? */ + ino_count = READ_ONCE(ino->count) + 1; + if (d_count(dentry) > ino_count) + return NULL; + } + + expired = autofs_check_leaves(mnt, dentry, timeout, how); + if (expired) { + if (expired == dentry) + dput(dentry); + return expired; + } + } + return NULL; +} + +/* + * Find an eligible tree to time-out + * A tree is eligible if :- + * - it is unused by any user process + * - it has been unused for exp_timeout time + */ +static struct dentry *autofs_expire_indirect(struct super_block *sb, + struct vfsmount *mnt, + struct autofs_sb_info *sbi, + unsigned int how) +{ + unsigned long timeout; + struct dentry *root = sb->s_root; + struct dentry *dentry; + struct dentry *expired; + struct dentry *found; + struct autofs_info *ino; + + if (!root) + return NULL; + + timeout = sbi->exp_timeout; + + dentry = NULL; + while ((dentry = get_next_positive_subdir(dentry, root))) { + spin_lock(&sbi->fs_lock); + ino = autofs_dentry_ino(dentry); + if (ino->flags & AUTOFS_INF_WANT_EXPIRE) { + spin_unlock(&sbi->fs_lock); + continue; + } + spin_unlock(&sbi->fs_lock); + + expired = should_expire(dentry, mnt, timeout, how); + if (!expired) + continue; + + spin_lock(&sbi->fs_lock); + ino = autofs_dentry_ino(expired); + ino->flags |= AUTOFS_INF_WANT_EXPIRE; + spin_unlock(&sbi->fs_lock); + synchronize_rcu(); + + /* Make sure a reference is not taken on found if + * things have changed. + */ + how &= ~AUTOFS_EXP_LEAVES; + found = should_expire(expired, mnt, timeout, how); + if (found != expired) { // something has changed, continue + dput(found); + goto next; + } + + if (expired != dentry) + dput(dentry); + + spin_lock(&sbi->fs_lock); + goto found; +next: + spin_lock(&sbi->fs_lock); + ino->flags &= ~AUTOFS_INF_WANT_EXPIRE; + spin_unlock(&sbi->fs_lock); + if (expired != dentry) + dput(expired); + } + return NULL; + +found: + pr_debug("returning %p %pd\n", expired, expired); + ino->flags |= AUTOFS_INF_EXPIRING; + init_completion(&ino->expire_complete); + spin_unlock(&sbi->fs_lock); + return expired; +} + +int autofs_expire_wait(const struct path *path, int rcu_walk) +{ + struct dentry *dentry = path->dentry; + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + int status; + int state; + + /* Block on any pending expire */ + if (!(ino->flags & AUTOFS_INF_WANT_EXPIRE)) + return 0; + if (rcu_walk) + return -ECHILD; + +retry: + spin_lock(&sbi->fs_lock); + state = ino->flags & (AUTOFS_INF_WANT_EXPIRE | AUTOFS_INF_EXPIRING); + if (state == AUTOFS_INF_WANT_EXPIRE) { + spin_unlock(&sbi->fs_lock); + /* + * Possibly being selected for expire, wait until + * it's selected or not. + */ + schedule_timeout_uninterruptible(HZ/10); + goto retry; + } + if (state & AUTOFS_INF_EXPIRING) { + spin_unlock(&sbi->fs_lock); + + pr_debug("waiting for expire %p name=%pd\n", dentry, dentry); + + status = autofs_wait(sbi, path, NFY_NONE); + wait_for_completion(&ino->expire_complete); + + pr_debug("expire done status=%d\n", status); + + if (d_unhashed(dentry)) + return -EAGAIN; + + return status; + } + spin_unlock(&sbi->fs_lock); + + return 0; +} + +/* Perform an expiry operation */ +int autofs_expire_run(struct super_block *sb, + struct vfsmount *mnt, + struct autofs_sb_info *sbi, + struct autofs_packet_expire __user *pkt_p) +{ + struct autofs_packet_expire pkt; + struct autofs_info *ino; + struct dentry *dentry; + int ret = 0; + + memset(&pkt, 0, sizeof(pkt)); + + pkt.hdr.proto_version = sbi->version; + pkt.hdr.type = autofs_ptype_expire; + + dentry = autofs_expire_indirect(sb, mnt, sbi, 0); + if (!dentry) + return -EAGAIN; + + pkt.len = dentry->d_name.len; + memcpy(pkt.name, dentry->d_name.name, pkt.len); + pkt.name[pkt.len] = '\0'; + + if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire))) + ret = -EFAULT; + + spin_lock(&sbi->fs_lock); + ino = autofs_dentry_ino(dentry); + /* avoid rapid-fire expire attempts if expiry fails */ + ino->last_used = jiffies; + ino->flags &= ~(AUTOFS_INF_EXPIRING|AUTOFS_INF_WANT_EXPIRE); + complete_all(&ino->expire_complete); + spin_unlock(&sbi->fs_lock); + + dput(dentry); + + return ret; +} + +int autofs_do_expire_multi(struct super_block *sb, struct vfsmount *mnt, + struct autofs_sb_info *sbi, unsigned int how) +{ + struct dentry *dentry; + int ret = -EAGAIN; + + if (autofs_type_trigger(sbi->type)) + dentry = autofs_expire_direct(sb, mnt, sbi, how); + else + dentry = autofs_expire_indirect(sb, mnt, sbi, how); + + if (dentry) { + struct autofs_info *ino = autofs_dentry_ino(dentry); + const struct path path = { .mnt = mnt, .dentry = dentry }; + + /* This is synchronous because it makes the daemon a + * little easier + */ + ret = autofs_wait(sbi, &path, NFY_EXPIRE); + + spin_lock(&sbi->fs_lock); + /* avoid rapid-fire expire attempts if expiry fails */ + ino->last_used = jiffies; + ino->flags &= ~(AUTOFS_INF_EXPIRING|AUTOFS_INF_WANT_EXPIRE); + complete_all(&ino->expire_complete); + spin_unlock(&sbi->fs_lock); + dput(dentry); + } + + return ret; +} + +/* + * Call repeatedly until it returns -EAGAIN, meaning there's nothing + * more to be done. + */ +int autofs_expire_multi(struct super_block *sb, struct vfsmount *mnt, + struct autofs_sb_info *sbi, int __user *arg) +{ + unsigned int how = 0; + + if (arg && get_user(how, arg)) + return -EFAULT; + + return autofs_do_expire_multi(sb, mnt, sbi, how); +} diff --git a/fs/autofs/init.c b/fs/autofs/init.c new file mode 100644 index 000000000..d3f55e874 --- /dev/null +++ b/fs/autofs/init.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved + */ + +#include <linux/module.h> +#include <linux/init.h> +#include "autofs_i.h" + +static struct dentry *autofs_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data) +{ + return mount_nodev(fs_type, flags, data, autofs_fill_super); +} + +struct file_system_type autofs_fs_type = { + .owner = THIS_MODULE, + .name = "autofs", + .mount = autofs_mount, + .kill_sb = autofs_kill_sb, +}; +MODULE_ALIAS_FS("autofs"); +MODULE_ALIAS("autofs"); + +static int __init init_autofs_fs(void) +{ + int err; + + autofs_dev_ioctl_init(); + + err = register_filesystem(&autofs_fs_type); + if (err) + autofs_dev_ioctl_exit(); + + return err; +} + +static void __exit exit_autofs_fs(void) +{ + autofs_dev_ioctl_exit(); + unregister_filesystem(&autofs_fs_type); +} + +module_init(init_autofs_fs) +module_exit(exit_autofs_fs) +MODULE_LICENSE("GPL"); diff --git a/fs/autofs/inode.c b/fs/autofs/inode.c new file mode 100644 index 000000000..affa70360 --- /dev/null +++ b/fs/autofs/inode.c @@ -0,0 +1,386 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved + * Copyright 2005-2006 Ian Kent <raven@themaw.net> + */ + +#include <linux/seq_file.h> +#include <linux/pagemap.h> +#include <linux/parser.h> + +#include "autofs_i.h" + +struct autofs_info *autofs_new_ino(struct autofs_sb_info *sbi) +{ + struct autofs_info *ino; + + ino = kzalloc(sizeof(*ino), GFP_KERNEL); + if (ino) { + INIT_LIST_HEAD(&ino->active); + INIT_LIST_HEAD(&ino->expiring); + ino->last_used = jiffies; + ino->sbi = sbi; + ino->count = 1; + } + return ino; +} + +void autofs_clean_ino(struct autofs_info *ino) +{ + ino->uid = GLOBAL_ROOT_UID; + ino->gid = GLOBAL_ROOT_GID; + ino->last_used = jiffies; +} + +void autofs_free_ino(struct autofs_info *ino) +{ + kfree_rcu(ino, rcu); +} + +void autofs_kill_sb(struct super_block *sb) +{ + struct autofs_sb_info *sbi = autofs_sbi(sb); + + /* + * In the event of a failure in get_sb_nodev the superblock + * info is not present so nothing else has been setup, so + * just call kill_anon_super when we are called from + * deactivate_super. + */ + if (sbi) { + /* Free wait queues, close pipe */ + autofs_catatonic_mode(sbi); + put_pid(sbi->oz_pgrp); + } + + pr_debug("shutting down\n"); + kill_litter_super(sb); + if (sbi) + kfree_rcu(sbi, rcu); +} + +static int autofs_show_options(struct seq_file *m, struct dentry *root) +{ + struct autofs_sb_info *sbi = autofs_sbi(root->d_sb); + struct inode *root_inode = d_inode(root->d_sb->s_root); + + if (!sbi) + return 0; + + seq_printf(m, ",fd=%d", sbi->pipefd); + if (!uid_eq(root_inode->i_uid, GLOBAL_ROOT_UID)) + seq_printf(m, ",uid=%u", + from_kuid_munged(&init_user_ns, root_inode->i_uid)); + if (!gid_eq(root_inode->i_gid, GLOBAL_ROOT_GID)) + seq_printf(m, ",gid=%u", + from_kgid_munged(&init_user_ns, root_inode->i_gid)); + seq_printf(m, ",pgrp=%d", pid_vnr(sbi->oz_pgrp)); + seq_printf(m, ",timeout=%lu", sbi->exp_timeout/HZ); + seq_printf(m, ",minproto=%d", sbi->min_proto); + seq_printf(m, ",maxproto=%d", sbi->max_proto); + + if (autofs_type_offset(sbi->type)) + seq_puts(m, ",offset"); + else if (autofs_type_direct(sbi->type)) + seq_puts(m, ",direct"); + else + seq_puts(m, ",indirect"); + if (sbi->flags & AUTOFS_SBI_STRICTEXPIRE) + seq_puts(m, ",strictexpire"); + if (sbi->flags & AUTOFS_SBI_IGNORE) + seq_puts(m, ",ignore"); +#ifdef CONFIG_CHECKPOINT_RESTORE + if (sbi->pipe) + seq_printf(m, ",pipe_ino=%ld", file_inode(sbi->pipe)->i_ino); + else + seq_puts(m, ",pipe_ino=-1"); +#endif + return 0; +} + +static void autofs_evict_inode(struct inode *inode) +{ + clear_inode(inode); + kfree(inode->i_private); +} + +static const struct super_operations autofs_sops = { + .statfs = simple_statfs, + .show_options = autofs_show_options, + .evict_inode = autofs_evict_inode, +}; + +enum {Opt_err, Opt_fd, Opt_uid, Opt_gid, Opt_pgrp, Opt_minproto, Opt_maxproto, + Opt_indirect, Opt_direct, Opt_offset, Opt_strictexpire, + Opt_ignore}; + +static const match_table_t tokens = { + {Opt_fd, "fd=%u"}, + {Opt_uid, "uid=%u"}, + {Opt_gid, "gid=%u"}, + {Opt_pgrp, "pgrp=%u"}, + {Opt_minproto, "minproto=%u"}, + {Opt_maxproto, "maxproto=%u"}, + {Opt_indirect, "indirect"}, + {Opt_direct, "direct"}, + {Opt_offset, "offset"}, + {Opt_strictexpire, "strictexpire"}, + {Opt_ignore, "ignore"}, + {Opt_err, NULL} +}; + +static int parse_options(char *options, + struct inode *root, int *pgrp, bool *pgrp_set, + struct autofs_sb_info *sbi) +{ + char *p; + substring_t args[MAX_OPT_ARGS]; + int option; + int pipefd = -1; + kuid_t uid; + kgid_t gid; + + root->i_uid = current_uid(); + root->i_gid = current_gid(); + + sbi->min_proto = AUTOFS_MIN_PROTO_VERSION; + sbi->max_proto = AUTOFS_MAX_PROTO_VERSION; + + sbi->pipefd = -1; + + if (!options) + return 1; + + while ((p = strsep(&options, ",")) != NULL) { + int token; + + if (!*p) + continue; + + token = match_token(p, tokens, args); + switch (token) { + case Opt_fd: + if (match_int(args, &pipefd)) + return 1; + sbi->pipefd = pipefd; + break; + case Opt_uid: + if (match_int(args, &option)) + return 1; + uid = make_kuid(current_user_ns(), option); + if (!uid_valid(uid)) + return 1; + root->i_uid = uid; + break; + case Opt_gid: + if (match_int(args, &option)) + return 1; + gid = make_kgid(current_user_ns(), option); + if (!gid_valid(gid)) + return 1; + root->i_gid = gid; + break; + case Opt_pgrp: + if (match_int(args, &option)) + return 1; + *pgrp = option; + *pgrp_set = true; + break; + case Opt_minproto: + if (match_int(args, &option)) + return 1; + sbi->min_proto = option; + break; + case Opt_maxproto: + if (match_int(args, &option)) + return 1; + sbi->max_proto = option; + break; + case Opt_indirect: + set_autofs_type_indirect(&sbi->type); + break; + case Opt_direct: + set_autofs_type_direct(&sbi->type); + break; + case Opt_offset: + set_autofs_type_offset(&sbi->type); + break; + case Opt_strictexpire: + sbi->flags |= AUTOFS_SBI_STRICTEXPIRE; + break; + case Opt_ignore: + sbi->flags |= AUTOFS_SBI_IGNORE; + break; + default: + return 1; + } + } + return (sbi->pipefd < 0); +} + +int autofs_fill_super(struct super_block *s, void *data, int silent) +{ + struct inode *root_inode; + struct dentry *root; + struct file *pipe; + struct autofs_sb_info *sbi; + struct autofs_info *ino; + int pgrp = 0; + bool pgrp_set = false; + int ret = -EINVAL; + + sbi = kzalloc(sizeof(*sbi), GFP_KERNEL); + if (!sbi) + return -ENOMEM; + pr_debug("starting up, sbi = %p\n", sbi); + + s->s_fs_info = sbi; + sbi->magic = AUTOFS_SBI_MAGIC; + sbi->pipefd = -1; + sbi->pipe = NULL; + sbi->exp_timeout = 0; + sbi->oz_pgrp = NULL; + sbi->sb = s; + sbi->version = 0; + sbi->sub_version = 0; + sbi->flags = AUTOFS_SBI_CATATONIC; + set_autofs_type_indirect(&sbi->type); + sbi->min_proto = 0; + sbi->max_proto = 0; + mutex_init(&sbi->wq_mutex); + mutex_init(&sbi->pipe_mutex); + spin_lock_init(&sbi->fs_lock); + sbi->queues = NULL; + spin_lock_init(&sbi->lookup_lock); + INIT_LIST_HEAD(&sbi->active_list); + INIT_LIST_HEAD(&sbi->expiring_list); + s->s_blocksize = 1024; + s->s_blocksize_bits = 10; + s->s_magic = AUTOFS_SUPER_MAGIC; + s->s_op = &autofs_sops; + s->s_d_op = &autofs_dentry_operations; + s->s_time_gran = 1; + + /* + * Get the root inode and dentry, but defer checking for errors. + */ + ino = autofs_new_ino(sbi); + if (!ino) { + ret = -ENOMEM; + goto fail_free; + } + root_inode = autofs_get_inode(s, S_IFDIR | 0755); + root = d_make_root(root_inode); + if (!root) { + ret = -ENOMEM; + goto fail_ino; + } + pipe = NULL; + + root->d_fsdata = ino; + + /* Can this call block? */ + if (parse_options(data, root_inode, &pgrp, &pgrp_set, sbi)) { + pr_err("called with bogus options\n"); + goto fail_dput; + } + + /* Test versions first */ + if (sbi->max_proto < AUTOFS_MIN_PROTO_VERSION || + sbi->min_proto > AUTOFS_MAX_PROTO_VERSION) { + pr_err("kernel does not match daemon version " + "daemon (%d, %d) kernel (%d, %d)\n", + sbi->min_proto, sbi->max_proto, + AUTOFS_MIN_PROTO_VERSION, AUTOFS_MAX_PROTO_VERSION); + goto fail_dput; + } + + /* Establish highest kernel protocol version */ + if (sbi->max_proto > AUTOFS_MAX_PROTO_VERSION) + sbi->version = AUTOFS_MAX_PROTO_VERSION; + else + sbi->version = sbi->max_proto; + sbi->sub_version = AUTOFS_PROTO_SUBVERSION; + + if (pgrp_set) { + sbi->oz_pgrp = find_get_pid(pgrp); + if (!sbi->oz_pgrp) { + pr_err("could not find process group %d\n", + pgrp); + goto fail_dput; + } + } else { + sbi->oz_pgrp = get_task_pid(current, PIDTYPE_PGID); + } + + if (autofs_type_trigger(sbi->type)) + __managed_dentry_set_managed(root); + + root_inode->i_fop = &autofs_root_operations; + root_inode->i_op = &autofs_dir_inode_operations; + + pr_debug("pipe fd = %d, pgrp = %u\n", + sbi->pipefd, pid_nr(sbi->oz_pgrp)); + pipe = fget(sbi->pipefd); + + if (!pipe) { + pr_err("could not open pipe file descriptor\n"); + goto fail_put_pid; + } + ret = autofs_prepare_pipe(pipe); + if (ret < 0) + goto fail_fput; + sbi->pipe = pipe; + sbi->flags &= ~AUTOFS_SBI_CATATONIC; + + /* + * Success! Install the root dentry now to indicate completion. + */ + s->s_root = root; + return 0; + + /* + * Failure ... clean up. + */ +fail_fput: + pr_err("pipe file descriptor does not contain proper ops\n"); + fput(pipe); +fail_put_pid: + put_pid(sbi->oz_pgrp); +fail_dput: + dput(root); + goto fail_free; +fail_ino: + autofs_free_ino(ino); +fail_free: + kfree(sbi); + s->s_fs_info = NULL; + return ret; +} + +struct inode *autofs_get_inode(struct super_block *sb, umode_t mode) +{ + struct inode *inode = new_inode(sb); + + if (inode == NULL) + return NULL; + + inode->i_mode = mode; + if (sb->s_root) { + inode->i_uid = d_inode(sb->s_root)->i_uid; + inode->i_gid = d_inode(sb->s_root)->i_gid; + } + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); + inode->i_ino = get_next_ino(); + + if (S_ISDIR(mode)) { + set_nlink(inode, 2); + inode->i_op = &autofs_dir_inode_operations; + inode->i_fop = &autofs_dir_operations; + } else if (S_ISLNK(mode)) { + inode->i_op = &autofs_symlink_inode_operations; + } else + WARN_ON(1); + + return inode; +} diff --git a/fs/autofs/root.c b/fs/autofs/root.c new file mode 100644 index 000000000..ca03c1cae --- /dev/null +++ b/fs/autofs/root.c @@ -0,0 +1,928 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved + * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org> + * Copyright 2001-2006 Ian Kent <raven@themaw.net> + */ + +#include <linux/capability.h> +#include <linux/compat.h> + +#include "autofs_i.h" + +static int autofs_dir_permission(struct user_namespace *, struct inode *, int); +static int autofs_dir_symlink(struct user_namespace *, struct inode *, + struct dentry *, const char *); +static int autofs_dir_unlink(struct inode *, struct dentry *); +static int autofs_dir_rmdir(struct inode *, struct dentry *); +static int autofs_dir_mkdir(struct user_namespace *, struct inode *, + struct dentry *, umode_t); +static long autofs_root_ioctl(struct file *, unsigned int, unsigned long); +#ifdef CONFIG_COMPAT +static long autofs_root_compat_ioctl(struct file *, + unsigned int, unsigned long); +#endif +static int autofs_dir_open(struct inode *inode, struct file *file); +static struct dentry *autofs_lookup(struct inode *, + struct dentry *, unsigned int); +static struct vfsmount *autofs_d_automount(struct path *); +static int autofs_d_manage(const struct path *, bool); +static void autofs_dentry_release(struct dentry *); + +const struct file_operations autofs_root_operations = { + .open = dcache_dir_open, + .release = dcache_dir_close, + .read = generic_read_dir, + .iterate_shared = dcache_readdir, + .llseek = dcache_dir_lseek, + .unlocked_ioctl = autofs_root_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = autofs_root_compat_ioctl, +#endif +}; + +const struct file_operations autofs_dir_operations = { + .open = autofs_dir_open, + .release = dcache_dir_close, + .read = generic_read_dir, + .iterate_shared = dcache_readdir, + .llseek = dcache_dir_lseek, +}; + +const struct inode_operations autofs_dir_inode_operations = { + .lookup = autofs_lookup, + .permission = autofs_dir_permission, + .unlink = autofs_dir_unlink, + .symlink = autofs_dir_symlink, + .mkdir = autofs_dir_mkdir, + .rmdir = autofs_dir_rmdir, +}; + +const struct dentry_operations autofs_dentry_operations = { + .d_automount = autofs_d_automount, + .d_manage = autofs_d_manage, + .d_release = autofs_dentry_release, +}; + +static void autofs_del_active(struct dentry *dentry) +{ + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct autofs_info *ino; + + ino = autofs_dentry_ino(dentry); + spin_lock(&sbi->lookup_lock); + list_del_init(&ino->active); + spin_unlock(&sbi->lookup_lock); +} + +static int autofs_dir_open(struct inode *inode, struct file *file) +{ + struct dentry *dentry = file->f_path.dentry; + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + + pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry); + + if (autofs_oz_mode(sbi)) + goto out; + + /* + * An empty directory in an autofs file system is always a + * mount point. The daemon must have failed to mount this + * during lookup so it doesn't exist. This can happen, for + * example, if user space returns an incorrect status for a + * mount request. Otherwise we're doing a readdir on the + * autofs file system so just let the libfs routines handle + * it. + */ + spin_lock(&sbi->lookup_lock); + if (!path_is_mountpoint(&file->f_path) && autofs_empty(ino)) { + spin_unlock(&sbi->lookup_lock); + return -ENOENT; + } + spin_unlock(&sbi->lookup_lock); + +out: + return dcache_dir_open(inode, file); +} + +static void autofs_dentry_release(struct dentry *de) +{ + struct autofs_info *ino = autofs_dentry_ino(de); + struct autofs_sb_info *sbi = autofs_sbi(de->d_sb); + + pr_debug("releasing %p\n", de); + + if (!ino) + return; + + if (sbi) { + spin_lock(&sbi->lookup_lock); + if (!list_empty(&ino->active)) + list_del(&ino->active); + if (!list_empty(&ino->expiring)) + list_del(&ino->expiring); + spin_unlock(&sbi->lookup_lock); + } + + autofs_free_ino(ino); +} + +static struct dentry *autofs_lookup_active(struct dentry *dentry) +{ + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct dentry *parent = dentry->d_parent; + const struct qstr *name = &dentry->d_name; + unsigned int len = name->len; + unsigned int hash = name->hash; + const unsigned char *str = name->name; + struct list_head *p, *head; + + head = &sbi->active_list; + if (list_empty(head)) + return NULL; + spin_lock(&sbi->lookup_lock); + list_for_each(p, head) { + struct autofs_info *ino; + struct dentry *active; + const struct qstr *qstr; + + ino = list_entry(p, struct autofs_info, active); + active = ino->dentry; + + spin_lock(&active->d_lock); + + /* Already gone? */ + if ((int) d_count(active) <= 0) + goto next; + + qstr = &active->d_name; + + if (active->d_name.hash != hash) + goto next; + if (active->d_parent != parent) + goto next; + + if (qstr->len != len) + goto next; + if (memcmp(qstr->name, str, len)) + goto next; + + if (d_unhashed(active)) { + dget_dlock(active); + spin_unlock(&active->d_lock); + spin_unlock(&sbi->lookup_lock); + return active; + } +next: + spin_unlock(&active->d_lock); + } + spin_unlock(&sbi->lookup_lock); + + return NULL; +} + +static struct dentry *autofs_lookup_expiring(struct dentry *dentry, + bool rcu_walk) +{ + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct dentry *parent = dentry->d_parent; + const struct qstr *name = &dentry->d_name; + unsigned int len = name->len; + unsigned int hash = name->hash; + const unsigned char *str = name->name; + struct list_head *p, *head; + + head = &sbi->expiring_list; + if (list_empty(head)) + return NULL; + spin_lock(&sbi->lookup_lock); + list_for_each(p, head) { + struct autofs_info *ino; + struct dentry *expiring; + const struct qstr *qstr; + + if (rcu_walk) { + spin_unlock(&sbi->lookup_lock); + return ERR_PTR(-ECHILD); + } + + ino = list_entry(p, struct autofs_info, expiring); + expiring = ino->dentry; + + spin_lock(&expiring->d_lock); + + /* We've already been dentry_iput or unlinked */ + if (d_really_is_negative(expiring)) + goto next; + + qstr = &expiring->d_name; + + if (expiring->d_name.hash != hash) + goto next; + if (expiring->d_parent != parent) + goto next; + + if (qstr->len != len) + goto next; + if (memcmp(qstr->name, str, len)) + goto next; + + if (d_unhashed(expiring)) { + dget_dlock(expiring); + spin_unlock(&expiring->d_lock); + spin_unlock(&sbi->lookup_lock); + return expiring; + } +next: + spin_unlock(&expiring->d_lock); + } + spin_unlock(&sbi->lookup_lock); + + return NULL; +} + +static int autofs_mount_wait(const struct path *path, bool rcu_walk) +{ + struct autofs_sb_info *sbi = autofs_sbi(path->dentry->d_sb); + struct autofs_info *ino = autofs_dentry_ino(path->dentry); + int status = 0; + + if (ino->flags & AUTOFS_INF_PENDING) { + if (rcu_walk) + return -ECHILD; + pr_debug("waiting for mount name=%pd\n", path->dentry); + status = autofs_wait(sbi, path, NFY_MOUNT); + pr_debug("mount wait done status=%d\n", status); + ino->last_used = jiffies; + return status; + } + if (!(sbi->flags & AUTOFS_SBI_STRICTEXPIRE)) + ino->last_used = jiffies; + return status; +} + +static int do_expire_wait(const struct path *path, bool rcu_walk) +{ + struct dentry *dentry = path->dentry; + struct dentry *expiring; + + expiring = autofs_lookup_expiring(dentry, rcu_walk); + if (IS_ERR(expiring)) + return PTR_ERR(expiring); + if (!expiring) + return autofs_expire_wait(path, rcu_walk); + else { + const struct path this = { .mnt = path->mnt, .dentry = expiring }; + /* + * If we are racing with expire the request might not + * be quite complete, but the directory has been removed + * so it must have been successful, just wait for it. + */ + autofs_expire_wait(&this, 0); + autofs_del_expiring(expiring); + dput(expiring); + } + return 0; +} + +static struct dentry *autofs_mountpoint_changed(struct path *path) +{ + struct dentry *dentry = path->dentry; + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + + /* If this is an indirect mount the dentry could have gone away + * and a new one created. + * + * This is unusual and I can't remember the case for which it + * was originally added now. But an example of how this can + * happen is an autofs indirect mount that has the "browse" + * option set and also has the "symlink" option in the autofs + * map entry. In this case the daemon will remove the browse + * directory and create a symlink as the mount leaving the + * struct path stale. + * + * Another not so obvious case is when a mount in an autofs + * indirect mount that uses the "nobrowse" option is being + * expired at the same time as a path walk. If the mount has + * been umounted but the mount point directory seen before + * becoming unhashed (during a lockless path walk) when a stat + * family system call is made the mount won't be re-mounted as + * it should. In this case the mount point that's been removed + * (by the daemon) will be stale and the a new mount point + * dentry created. + */ + if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) { + struct dentry *parent = dentry->d_parent; + struct autofs_info *ino; + struct dentry *new; + + new = d_lookup(parent, &dentry->d_name); + if (!new) + return NULL; + ino = autofs_dentry_ino(new); + ino->last_used = jiffies; + dput(path->dentry); + path->dentry = new; + } + return path->dentry; +} + +static struct vfsmount *autofs_d_automount(struct path *path) +{ + struct dentry *dentry = path->dentry; + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + int status; + + pr_debug("dentry=%p %pd\n", dentry, dentry); + + /* The daemon never triggers a mount. */ + if (autofs_oz_mode(sbi)) + return NULL; + + /* + * If an expire request is pending everyone must wait. + * If the expire fails we're still mounted so continue + * the follow and return. A return of -EAGAIN (which only + * happens with indirect mounts) means the expire completed + * and the directory was removed, so just go ahead and try + * the mount. + */ + status = do_expire_wait(path, 0); + if (status && status != -EAGAIN) + return NULL; + + /* Callback to the daemon to perform the mount or wait */ + spin_lock(&sbi->fs_lock); + if (ino->flags & AUTOFS_INF_PENDING) { + spin_unlock(&sbi->fs_lock); + status = autofs_mount_wait(path, 0); + if (status) + return ERR_PTR(status); + goto done; + } + + /* + * If the dentry is a symlink it's equivalent to a directory + * having path_is_mountpoint() true, so there's no need to call + * back to the daemon. + */ + if (d_really_is_positive(dentry) && d_is_symlink(dentry)) { + spin_unlock(&sbi->fs_lock); + goto done; + } + + if (!path_is_mountpoint(path)) { + /* + * It's possible that user space hasn't removed directories + * after umounting a rootless multi-mount, although it + * should. For v5 path_has_submounts() is sufficient to + * handle this because the leaves of the directory tree under + * the mount never trigger mounts themselves (they have an + * autofs trigger mount mounted on them). But v4 pseudo direct + * mounts do need the leaves to trigger mounts. In this case + * we have no choice but to use the autofs_empty() check and + * require user space behave. + */ + if (sbi->version > 4) { + if (path_has_submounts(path)) { + spin_unlock(&sbi->fs_lock); + goto done; + } + } else { + if (!autofs_empty(ino)) { + spin_unlock(&sbi->fs_lock); + goto done; + } + } + ino->flags |= AUTOFS_INF_PENDING; + spin_unlock(&sbi->fs_lock); + status = autofs_mount_wait(path, 0); + spin_lock(&sbi->fs_lock); + ino->flags &= ~AUTOFS_INF_PENDING; + if (status) { + spin_unlock(&sbi->fs_lock); + return ERR_PTR(status); + } + } + spin_unlock(&sbi->fs_lock); +done: + /* Mount succeeded, check if we ended up with a new dentry */ + dentry = autofs_mountpoint_changed(path); + if (!dentry) + return ERR_PTR(-ENOENT); + + return NULL; +} + +static int autofs_d_manage(const struct path *path, bool rcu_walk) +{ + struct dentry *dentry = path->dentry; + struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + int status; + + pr_debug("dentry=%p %pd\n", dentry, dentry); + + /* The daemon never waits. */ + if (autofs_oz_mode(sbi)) { + if (!path_is_mountpoint(path)) + return -EISDIR; + return 0; + } + + /* Wait for pending expires */ + if (do_expire_wait(path, rcu_walk) == -ECHILD) + return -ECHILD; + + /* + * This dentry may be under construction so wait on mount + * completion. + */ + status = autofs_mount_wait(path, rcu_walk); + if (status) + return status; + + if (rcu_walk) { + /* We don't need fs_lock in rcu_walk mode, + * just testing 'AUTOFS_INF_WANT_EXPIRE' is enough. + * + * We only return -EISDIR when certain this isn't + * a mount-trap. + */ + struct inode *inode; + + if (ino->flags & AUTOFS_INF_WANT_EXPIRE) + return 0; + if (path_is_mountpoint(path)) + return 0; + inode = d_inode_rcu(dentry); + if (inode && S_ISLNK(inode->i_mode)) + return -EISDIR; + if (!autofs_empty(ino)) + return -EISDIR; + return 0; + } + + spin_lock(&sbi->fs_lock); + /* + * If the dentry has been selected for expire while we slept + * on the lock then it might go away. We'll deal with that in + * ->d_automount() and wait on a new mount if the expire + * succeeds or return here if it doesn't (since there's no + * mount to follow with a rootless multi-mount). + */ + if (!(ino->flags & AUTOFS_INF_EXPIRING)) { + /* + * Any needed mounting has been completed and the path + * updated so check if this is a rootless multi-mount so + * we can avoid needless calls ->d_automount() and avoid + * an incorrect ELOOP error return. + */ + if ((!path_is_mountpoint(path) && !autofs_empty(ino)) || + (d_really_is_positive(dentry) && d_is_symlink(dentry))) + status = -EISDIR; + } + spin_unlock(&sbi->fs_lock); + + return status; +} + +/* Lookups in the root directory */ +static struct dentry *autofs_lookup(struct inode *dir, + struct dentry *dentry, unsigned int flags) +{ + struct autofs_sb_info *sbi; + struct autofs_info *ino; + struct dentry *active; + + pr_debug("name = %pd\n", dentry); + + /* File name too long to exist */ + if (dentry->d_name.len > NAME_MAX) + return ERR_PTR(-ENAMETOOLONG); + + sbi = autofs_sbi(dir->i_sb); + + pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n", + current->pid, task_pgrp_nr(current), + sbi->flags & AUTOFS_SBI_CATATONIC, + autofs_oz_mode(sbi)); + + active = autofs_lookup_active(dentry); + if (active) + return active; + else { + /* + * A dentry that is not within the root can never trigger a + * mount operation, unless the directory already exists, so we + * can return fail immediately. The daemon however does need + * to create directories within the file system. + */ + if (!autofs_oz_mode(sbi) && !IS_ROOT(dentry->d_parent)) + return ERR_PTR(-ENOENT); + + ino = autofs_new_ino(sbi); + if (!ino) + return ERR_PTR(-ENOMEM); + + spin_lock(&sbi->lookup_lock); + spin_lock(&dentry->d_lock); + /* Mark entries in the root as mount triggers */ + if (IS_ROOT(dentry->d_parent) && + autofs_type_indirect(sbi->type)) + __managed_dentry_set_managed(dentry); + dentry->d_fsdata = ino; + ino->dentry = dentry; + + list_add(&ino->active, &sbi->active_list); + spin_unlock(&sbi->lookup_lock); + spin_unlock(&dentry->d_lock); + } + return NULL; +} + +static int autofs_dir_permission(struct user_namespace *mnt_userns, + struct inode *inode, int mask) +{ + if (mask & MAY_WRITE) { + struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb); + + if (!autofs_oz_mode(sbi)) + return -EACCES; + + /* autofs_oz_mode() needs to allow path walks when the + * autofs mount is catatonic but the state of an autofs + * file system needs to be preserved over restarts. + */ + if (sbi->flags & AUTOFS_SBI_CATATONIC) + return -EACCES; + } + + return generic_permission(mnt_userns, inode, mask); +} + +static int autofs_dir_symlink(struct user_namespace *mnt_userns, + struct inode *dir, struct dentry *dentry, + const char *symname) +{ + struct autofs_info *ino = autofs_dentry_ino(dentry); + struct autofs_info *p_ino; + struct inode *inode; + size_t size = strlen(symname); + char *cp; + + pr_debug("%s <- %pd\n", symname, dentry); + + BUG_ON(!ino); + + autofs_clean_ino(ino); + + autofs_del_active(dentry); + + cp = kmalloc(size + 1, GFP_KERNEL); + if (!cp) + return -ENOMEM; + + strcpy(cp, symname); + + inode = autofs_get_inode(dir->i_sb, S_IFLNK | 0555); + if (!inode) { + kfree(cp); + return -ENOMEM; + } + inode->i_private = cp; + inode->i_size = size; + d_add(dentry, inode); + + dget(dentry); + p_ino = autofs_dentry_ino(dentry->d_parent); + p_ino->count++; + + dir->i_mtime = current_time(dir); + + return 0; +} + +/* + * NOTE! + * + * Normal filesystems would do a "d_delete()" to tell the VFS dcache + * that the file no longer exists. However, doing that means that the + * VFS layer can turn the dentry into a negative dentry. We don't want + * this, because the unlink is probably the result of an expire. + * We simply d_drop it and add it to a expiring list in the super block, + * which allows the dentry lookup to check for an incomplete expire. + * + * If a process is blocked on the dentry waiting for the expire to finish, + * it will invalidate the dentry and try to mount with a new one. + * + * Also see autofs_dir_rmdir().. + */ +static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry) +{ + struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + struct autofs_info *p_ino; + + p_ino = autofs_dentry_ino(dentry->d_parent); + p_ino->count--; + dput(ino->dentry); + + d_inode(dentry)->i_size = 0; + clear_nlink(d_inode(dentry)); + + dir->i_mtime = current_time(dir); + + spin_lock(&sbi->lookup_lock); + __autofs_add_expiring(dentry); + d_drop(dentry); + spin_unlock(&sbi->lookup_lock); + + return 0; +} + +/* + * Version 4 of autofs provides a pseudo direct mount implementation + * that relies on directories at the leaves of a directory tree under + * an indirect mount to trigger mounts. To allow for this we need to + * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves + * of the directory tree. There is no need to clear the automount flag + * following a mount or restore it after an expire because these mounts + * are always covered. However, it is necessary to ensure that these + * flags are clear on non-empty directories to avoid unnecessary calls + * during path walks. + */ +static void autofs_set_leaf_automount_flags(struct dentry *dentry) +{ + struct dentry *parent; + + /* root and dentrys in the root are already handled */ + if (IS_ROOT(dentry->d_parent)) + return; + + managed_dentry_set_managed(dentry); + + parent = dentry->d_parent; + /* only consider parents below dentrys in the root */ + if (IS_ROOT(parent->d_parent)) + return; + managed_dentry_clear_managed(parent); +} + +static void autofs_clear_leaf_automount_flags(struct dentry *dentry) +{ + struct dentry *parent; + + /* flags for dentrys in the root are handled elsewhere */ + if (IS_ROOT(dentry->d_parent)) + return; + + managed_dentry_clear_managed(dentry); + + parent = dentry->d_parent; + /* only consider parents below dentrys in the root */ + if (IS_ROOT(parent->d_parent)) + return; + if (autofs_dentry_ino(parent)->count == 2) + managed_dentry_set_managed(parent); +} + +static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry) +{ + struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + struct autofs_info *p_ino; + + pr_debug("dentry %p, removing %pd\n", dentry, dentry); + + if (ino->count != 1) + return -ENOTEMPTY; + + spin_lock(&sbi->lookup_lock); + __autofs_add_expiring(dentry); + d_drop(dentry); + spin_unlock(&sbi->lookup_lock); + + if (sbi->version < 5) + autofs_clear_leaf_automount_flags(dentry); + + p_ino = autofs_dentry_ino(dentry->d_parent); + p_ino->count--; + dput(ino->dentry); + d_inode(dentry)->i_size = 0; + clear_nlink(d_inode(dentry)); + + if (dir->i_nlink) + drop_nlink(dir); + + return 0; +} + +static int autofs_dir_mkdir(struct user_namespace *mnt_userns, + struct inode *dir, struct dentry *dentry, + umode_t mode) +{ + struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb); + struct autofs_info *ino = autofs_dentry_ino(dentry); + struct autofs_info *p_ino; + struct inode *inode; + + pr_debug("dentry %p, creating %pd\n", dentry, dentry); + + BUG_ON(!ino); + + autofs_clean_ino(ino); + + autofs_del_active(dentry); + + inode = autofs_get_inode(dir->i_sb, S_IFDIR | mode); + if (!inode) + return -ENOMEM; + d_add(dentry, inode); + + if (sbi->version < 5) + autofs_set_leaf_automount_flags(dentry); + + dget(dentry); + p_ino = autofs_dentry_ino(dentry->d_parent); + p_ino->count++; + inc_nlink(dir); + dir->i_mtime = current_time(dir); + + return 0; +} + +/* Get/set timeout ioctl() operation */ +#ifdef CONFIG_COMPAT +static inline int autofs_compat_get_set_timeout(struct autofs_sb_info *sbi, + compat_ulong_t __user *p) +{ + unsigned long ntimeout; + int rv; + + rv = get_user(ntimeout, p); + if (rv) + goto error; + + rv = put_user(sbi->exp_timeout/HZ, p); + if (rv) + goto error; + + if (ntimeout > UINT_MAX/HZ) + sbi->exp_timeout = 0; + else + sbi->exp_timeout = ntimeout * HZ; + + return 0; +error: + return rv; +} +#endif + +static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi, + unsigned long __user *p) +{ + unsigned long ntimeout; + int rv; + + rv = get_user(ntimeout, p); + if (rv) + goto error; + + rv = put_user(sbi->exp_timeout/HZ, p); + if (rv) + goto error; + + if (ntimeout > ULONG_MAX/HZ) + sbi->exp_timeout = 0; + else + sbi->exp_timeout = ntimeout * HZ; + + return 0; +error: + return rv; +} + +/* Return protocol version */ +static inline int autofs_get_protover(struct autofs_sb_info *sbi, + int __user *p) +{ + return put_user(sbi->version, p); +} + +/* Return protocol sub version */ +static inline int autofs_get_protosubver(struct autofs_sb_info *sbi, + int __user *p) +{ + return put_user(sbi->sub_version, p); +} + +/* +* Tells the daemon whether it can umount the autofs mount. +*/ +static inline int autofs_ask_umount(struct vfsmount *mnt, int __user *p) +{ + int status = 0; + + if (may_umount(mnt)) + status = 1; + + pr_debug("may umount %d\n", status); + + status = put_user(status, p); + + return status; +} + +/* Identify autofs_dentries - this is so we can tell if there's + * an extra dentry refcount or not. We only hold a refcount on the + * dentry if its non-negative (ie, d_inode != NULL) + */ +int is_autofs_dentry(struct dentry *dentry) +{ + return dentry && d_really_is_positive(dentry) && + dentry->d_op == &autofs_dentry_operations && + dentry->d_fsdata != NULL; +} + +/* + * ioctl()'s on the root directory is the chief method for the daemon to + * generate kernel reactions + */ +static int autofs_root_ioctl_unlocked(struct inode *inode, struct file *filp, + unsigned int cmd, unsigned long arg) +{ + struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb); + void __user *p = (void __user *)arg; + + pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n", + cmd, arg, sbi, task_pgrp_nr(current)); + + if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) || + _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT) + return -ENOTTY; + + if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + switch (cmd) { + case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */ + return autofs_wait_release(sbi, (autofs_wqt_t) arg, 0); + case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */ + return autofs_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT); + case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */ + autofs_catatonic_mode(sbi); + return 0; + case AUTOFS_IOC_PROTOVER: /* Get protocol version */ + return autofs_get_protover(sbi, p); + case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */ + return autofs_get_protosubver(sbi, p); + case AUTOFS_IOC_SETTIMEOUT: + return autofs_get_set_timeout(sbi, p); +#ifdef CONFIG_COMPAT + case AUTOFS_IOC_SETTIMEOUT32: + return autofs_compat_get_set_timeout(sbi, p); +#endif + + case AUTOFS_IOC_ASKUMOUNT: + return autofs_ask_umount(filp->f_path.mnt, p); + + /* return a single thing to expire */ + case AUTOFS_IOC_EXPIRE: + return autofs_expire_run(inode->i_sb, filp->f_path.mnt, sbi, p); + /* same as above, but can send multiple expires through pipe */ + case AUTOFS_IOC_EXPIRE_MULTI: + return autofs_expire_multi(inode->i_sb, + filp->f_path.mnt, sbi, p); + + default: + return -EINVAL; + } +} + +static long autofs_root_ioctl(struct file *filp, + unsigned int cmd, unsigned long arg) +{ + struct inode *inode = file_inode(filp); + + return autofs_root_ioctl_unlocked(inode, filp, cmd, arg); +} + +#ifdef CONFIG_COMPAT +static long autofs_root_compat_ioctl(struct file *filp, + unsigned int cmd, unsigned long arg) +{ + struct inode *inode = file_inode(filp); + int ret; + + if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL) + ret = autofs_root_ioctl_unlocked(inode, filp, cmd, arg); + else + ret = autofs_root_ioctl_unlocked(inode, filp, cmd, + (unsigned long) compat_ptr(arg)); + + return ret; +} +#endif diff --git a/fs/autofs/symlink.c b/fs/autofs/symlink.c new file mode 100644 index 000000000..7ac67dc76 --- /dev/null +++ b/fs/autofs/symlink.c @@ -0,0 +1,26 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved + */ + +#include "autofs_i.h" + +static const char *autofs_get_link(struct dentry *dentry, + struct inode *inode, + struct delayed_call *done) +{ + struct autofs_sb_info *sbi; + struct autofs_info *ino; + + if (!dentry) + return ERR_PTR(-ECHILD); + sbi = autofs_sbi(dentry->d_sb); + ino = autofs_dentry_ino(dentry); + if (ino && !autofs_oz_mode(sbi)) + ino->last_used = jiffies; + return d_inode(dentry)->i_private; +} + +const struct inode_operations autofs_symlink_inode_operations = { + .get_link = autofs_get_link +}; diff --git a/fs/autofs/waitq.c b/fs/autofs/waitq.c new file mode 100644 index 000000000..efdc76732 --- /dev/null +++ b/fs/autofs/waitq.c @@ -0,0 +1,513 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved + * Copyright 2001-2006 Ian Kent <raven@themaw.net> + */ + +#include <linux/sched/signal.h> +#include "autofs_i.h" + +/* We make this a static variable rather than a part of the superblock; it + * is better if we don't reassign numbers easily even across filesystems + */ +static autofs_wqt_t autofs_next_wait_queue = 1; + +void autofs_catatonic_mode(struct autofs_sb_info *sbi) +{ + struct autofs_wait_queue *wq, *nwq; + + mutex_lock(&sbi->wq_mutex); + if (sbi->flags & AUTOFS_SBI_CATATONIC) { + mutex_unlock(&sbi->wq_mutex); + return; + } + + pr_debug("entering catatonic mode\n"); + + sbi->flags |= AUTOFS_SBI_CATATONIC; + wq = sbi->queues; + sbi->queues = NULL; /* Erase all wait queues */ + while (wq) { + nwq = wq->next; + wq->status = -ENOENT; /* Magic is gone - report failure */ + kfree(wq->name.name - wq->offset); + wq->name.name = NULL; + wake_up_interruptible(&wq->queue); + if (!--wq->wait_ctr) + kfree(wq); + wq = nwq; + } + fput(sbi->pipe); /* Close the pipe */ + sbi->pipe = NULL; + sbi->pipefd = -1; + mutex_unlock(&sbi->wq_mutex); +} + +static int autofs_write(struct autofs_sb_info *sbi, + struct file *file, const void *addr, int bytes) +{ + unsigned long sigpipe, flags; + const char *data = (const char *)addr; + ssize_t wr = 0; + + sigpipe = sigismember(¤t->pending.signal, SIGPIPE); + + mutex_lock(&sbi->pipe_mutex); + while (bytes) { + wr = __kernel_write(file, data, bytes, NULL); + if (wr <= 0) + break; + data += wr; + bytes -= wr; + } + mutex_unlock(&sbi->pipe_mutex); + + /* Keep the currently executing process from receiving a + * SIGPIPE unless it was already supposed to get one + */ + if (wr == -EPIPE && !sigpipe) { + spin_lock_irqsave(¤t->sighand->siglock, flags); + sigdelset(¤t->pending.signal, SIGPIPE); + recalc_sigpending(); + spin_unlock_irqrestore(¤t->sighand->siglock, flags); + } + + /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */ + return bytes == 0 ? 0 : wr < 0 ? wr : -EIO; +} + +static void autofs_notify_daemon(struct autofs_sb_info *sbi, + struct autofs_wait_queue *wq, + int type) +{ + union { + struct autofs_packet_hdr hdr; + union autofs_packet_union v4_pkt; + union autofs_v5_packet_union v5_pkt; + } pkt; + struct file *pipe = NULL; + size_t pktsz; + int ret; + + pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n", + (unsigned long) wq->wait_queue_token, + wq->name.len, wq->name.name, type); + + memset(&pkt, 0, sizeof(pkt)); /* For security reasons */ + + pkt.hdr.proto_version = sbi->version; + pkt.hdr.type = type; + + switch (type) { + /* Kernel protocol v4 missing and expire packets */ + case autofs_ptype_missing: + { + struct autofs_packet_missing *mp = &pkt.v4_pkt.missing; + + pktsz = sizeof(*mp); + + mp->wait_queue_token = wq->wait_queue_token; + mp->len = wq->name.len; + memcpy(mp->name, wq->name.name, wq->name.len); + mp->name[wq->name.len] = '\0'; + break; + } + case autofs_ptype_expire_multi: + { + struct autofs_packet_expire_multi *ep = + &pkt.v4_pkt.expire_multi; + + pktsz = sizeof(*ep); + + ep->wait_queue_token = wq->wait_queue_token; + ep->len = wq->name.len; + memcpy(ep->name, wq->name.name, wq->name.len); + ep->name[wq->name.len] = '\0'; + break; + } + /* + * Kernel protocol v5 packet for handling indirect and direct + * mount missing and expire requests + */ + case autofs_ptype_missing_indirect: + case autofs_ptype_expire_indirect: + case autofs_ptype_missing_direct: + case autofs_ptype_expire_direct: + { + struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet; + struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns; + + pktsz = sizeof(*packet); + + packet->wait_queue_token = wq->wait_queue_token; + packet->len = wq->name.len; + memcpy(packet->name, wq->name.name, wq->name.len); + packet->name[wq->name.len] = '\0'; + packet->dev = wq->dev; + packet->ino = wq->ino; + packet->uid = from_kuid_munged(user_ns, wq->uid); + packet->gid = from_kgid_munged(user_ns, wq->gid); + packet->pid = wq->pid; + packet->tgid = wq->tgid; + break; + } + default: + pr_warn("bad type %d!\n", type); + mutex_unlock(&sbi->wq_mutex); + return; + } + + pipe = get_file(sbi->pipe); + + mutex_unlock(&sbi->wq_mutex); + + switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) { + case 0: + break; + case -ENOMEM: + case -ERESTARTSYS: + /* Just fail this one */ + autofs_wait_release(sbi, wq->wait_queue_token, ret); + break; + default: + autofs_catatonic_mode(sbi); + break; + } + fput(pipe); +} + +static struct autofs_wait_queue * +autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr) +{ + struct autofs_wait_queue *wq; + + for (wq = sbi->queues; wq; wq = wq->next) { + if (wq->name.hash == qstr->hash && + wq->name.len == qstr->len && + wq->name.name && + !memcmp(wq->name.name, qstr->name, qstr->len)) + break; + } + return wq; +} + +/* + * Check if we have a valid request. + * Returns + * 1 if the request should continue. + * In this case we can return an autofs_wait_queue entry if one is + * found or NULL to idicate a new wait needs to be created. + * 0 or a negative errno if the request shouldn't continue. + */ +static int validate_request(struct autofs_wait_queue **wait, + struct autofs_sb_info *sbi, + const struct qstr *qstr, + const struct path *path, enum autofs_notify notify) +{ + struct dentry *dentry = path->dentry; + struct autofs_wait_queue *wq; + struct autofs_info *ino; + + if (sbi->flags & AUTOFS_SBI_CATATONIC) + return -ENOENT; + + /* Wait in progress, continue; */ + wq = autofs_find_wait(sbi, qstr); + if (wq) { + *wait = wq; + return 1; + } + + *wait = NULL; + + /* If we don't yet have any info this is a new request */ + ino = autofs_dentry_ino(dentry); + if (!ino) + return 1; + + /* + * If we've been asked to wait on an existing expire (NFY_NONE) + * but there is no wait in the queue ... + */ + if (notify == NFY_NONE) { + /* + * Either we've betean the pending expire to post it's + * wait or it finished while we waited on the mutex. + * So we need to wait till either, the wait appears + * or the expire finishes. + */ + + while (ino->flags & AUTOFS_INF_EXPIRING) { + mutex_unlock(&sbi->wq_mutex); + schedule_timeout_interruptible(HZ/10); + if (mutex_lock_interruptible(&sbi->wq_mutex)) + return -EINTR; + + if (sbi->flags & AUTOFS_SBI_CATATONIC) + return -ENOENT; + + wq = autofs_find_wait(sbi, qstr); + if (wq) { + *wait = wq; + return 1; + } + } + + /* + * Not ideal but the status has already gone. Of the two + * cases where we wait on NFY_NONE neither depend on the + * return status of the wait. + */ + return 0; + } + + /* + * If we've been asked to trigger a mount and the request + * completed while we waited on the mutex ... + */ + if (notify == NFY_MOUNT) { + struct dentry *new = NULL; + struct path this; + int valid = 1; + + /* + * If the dentry was successfully mounted while we slept + * on the wait queue mutex we can return success. If it + * isn't mounted (doesn't have submounts for the case of + * a multi-mount with no mount at it's base) we can + * continue on and create a new request. + */ + if (!IS_ROOT(dentry)) { + if (d_unhashed(dentry) && + d_really_is_positive(dentry)) { + struct dentry *parent = dentry->d_parent; + + new = d_lookup(parent, &dentry->d_name); + if (new) + dentry = new; + } + } + this.mnt = path->mnt; + this.dentry = dentry; + if (path_has_submounts(&this)) + valid = 0; + + if (new) + dput(new); + return valid; + } + + return 1; +} + +int autofs_wait(struct autofs_sb_info *sbi, + const struct path *path, enum autofs_notify notify) +{ + struct dentry *dentry = path->dentry; + struct autofs_wait_queue *wq; + struct qstr qstr; + char *name; + int status, ret, type; + unsigned int offset = 0; + pid_t pid; + pid_t tgid; + + /* In catatonic mode, we don't wait for nobody */ + if (sbi->flags & AUTOFS_SBI_CATATONIC) + return -ENOENT; + + /* + * Try translating pids to the namespace of the daemon. + * + * Zero means failure: we are in an unrelated pid namespace. + */ + pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp)); + tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp)); + if (pid == 0 || tgid == 0) + return -ENOENT; + + if (d_really_is_negative(dentry)) { + /* + * A wait for a negative dentry is invalid for certain + * cases. A direct or offset mount "always" has its mount + * point directory created and so the request dentry must + * be positive or the map key doesn't exist. The situation + * is very similar for indirect mounts except only dentrys + * in the root of the autofs file system may be negative. + */ + if (autofs_type_trigger(sbi->type)) + return -ENOENT; + else if (!IS_ROOT(dentry->d_parent)) + return -ENOENT; + } + + name = kmalloc(NAME_MAX + 1, GFP_KERNEL); + if (!name) + return -ENOMEM; + + /* If this is a direct mount request create a dummy name */ + if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type)) { + qstr.name = name; + qstr.len = sprintf(name, "%p", dentry); + } else { + char *p = dentry_path_raw(dentry, name, NAME_MAX); + if (IS_ERR(p)) { + kfree(name); + return -ENOENT; + } + qstr.name = ++p; // skip the leading slash + qstr.len = strlen(p); + offset = p - name; + } + qstr.hash = full_name_hash(dentry, qstr.name, qstr.len); + + if (mutex_lock_interruptible(&sbi->wq_mutex)) { + kfree(name); + return -EINTR; + } + + ret = validate_request(&wq, sbi, &qstr, path, notify); + if (ret <= 0) { + if (ret != -EINTR) + mutex_unlock(&sbi->wq_mutex); + kfree(name); + return ret; + } + + if (!wq) { + /* Create a new wait queue */ + wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL); + if (!wq) { + kfree(name); + mutex_unlock(&sbi->wq_mutex); + return -ENOMEM; + } + + wq->wait_queue_token = autofs_next_wait_queue; + if (++autofs_next_wait_queue == 0) + autofs_next_wait_queue = 1; + wq->next = sbi->queues; + sbi->queues = wq; + init_waitqueue_head(&wq->queue); + memcpy(&wq->name, &qstr, sizeof(struct qstr)); + wq->offset = offset; + wq->dev = autofs_get_dev(sbi); + wq->ino = autofs_get_ino(sbi); + wq->uid = current_uid(); + wq->gid = current_gid(); + wq->pid = pid; + wq->tgid = tgid; + wq->status = -EINTR; /* Status return if interrupted */ + wq->wait_ctr = 2; + + if (sbi->version < 5) { + if (notify == NFY_MOUNT) + type = autofs_ptype_missing; + else + type = autofs_ptype_expire_multi; + } else { + if (notify == NFY_MOUNT) + type = autofs_type_trigger(sbi->type) ? + autofs_ptype_missing_direct : + autofs_ptype_missing_indirect; + else + type = autofs_type_trigger(sbi->type) ? + autofs_ptype_expire_direct : + autofs_ptype_expire_indirect; + } + + pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n", + (unsigned long) wq->wait_queue_token, wq->name.len, + wq->name.name, notify); + + /* + * autofs_notify_daemon() may block; it will unlock ->wq_mutex + */ + autofs_notify_daemon(sbi, wq, type); + } else { + wq->wait_ctr++; + pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n", + (unsigned long) wq->wait_queue_token, wq->name.len, + wq->name.name, notify); + mutex_unlock(&sbi->wq_mutex); + kfree(name); + } + + /* + * wq->name.name is NULL iff the lock is already released + * or the mount has been made catatonic. + */ + wait_event_killable(wq->queue, wq->name.name == NULL); + status = wq->status; + + /* + * For direct and offset mounts we need to track the requester's + * uid and gid in the dentry info struct. This is so it can be + * supplied, on request, by the misc device ioctl interface. + * This is needed during daemon resatart when reconnecting + * to existing, active, autofs mounts. The uid and gid (and + * related string values) may be used for macro substitution + * in autofs mount maps. + */ + if (!status) { + struct autofs_info *ino; + struct dentry *de = NULL; + + /* direct mount or browsable map */ + ino = autofs_dentry_ino(dentry); + if (!ino) { + /* If not lookup actual dentry used */ + de = d_lookup(dentry->d_parent, &dentry->d_name); + if (de) + ino = autofs_dentry_ino(de); + } + + /* Set mount requester */ + if (ino) { + spin_lock(&sbi->fs_lock); + ino->uid = wq->uid; + ino->gid = wq->gid; + spin_unlock(&sbi->fs_lock); + } + + if (de) + dput(de); + } + + /* Are we the last process to need status? */ + mutex_lock(&sbi->wq_mutex); + if (!--wq->wait_ctr) + kfree(wq); + mutex_unlock(&sbi->wq_mutex); + + return status; +} + + +int autofs_wait_release(struct autofs_sb_info *sbi, + autofs_wqt_t wait_queue_token, int status) +{ + struct autofs_wait_queue *wq, **wql; + + mutex_lock(&sbi->wq_mutex); + for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) { + if (wq->wait_queue_token == wait_queue_token) + break; + } + + if (!wq) { + mutex_unlock(&sbi->wq_mutex); + return -EINVAL; + } + + *wql = wq->next; /* Unlink from chain */ + kfree(wq->name.name - wq->offset); + wq->name.name = NULL; /* Do not wait on this queue */ + wq->status = status; + wake_up(&wq->queue); + if (!--wq->wait_ctr) + kfree(wq); + mutex_unlock(&sbi->wq_mutex); + + return 0; +} |