diff options
Diffstat (limited to 'fs/fcntl.c')
| -rw-r--r-- | fs/fcntl.c | 1041 |
1 files changed, 1041 insertions, 0 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c new file mode 100644 index 000000000..146c9ab0c --- /dev/null +++ b/fs/fcntl.c @@ -0,0 +1,1041 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/fcntl.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include <linux/syscalls.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/sched/task.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/fdtable.h> +#include <linux/capability.h> +#include <linux/dnotify.h> +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/pipe_fs_i.h> +#include <linux/security.h> +#include <linux/ptrace.h> +#include <linux/signal.h> +#include <linux/rcupdate.h> +#include <linux/pid_namespace.h> +#include <linux/user_namespace.h> +#include <linux/memfd.h> +#include <linux/compat.h> +#include <linux/mount.h> + +#include <linux/poll.h> +#include <asm/siginfo.h> +#include <linux/uaccess.h> + +#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) + +static int setfl(int fd, struct file * filp, unsigned long arg) +{ + struct inode * inode = file_inode(filp); + int error = 0; + + /* + * O_APPEND cannot be cleared if the file is marked as append-only + * and the file is open for write. + */ + if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) + return -EPERM; + + /* O_NOATIME can only be set by the owner or superuser */ + if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) + if (!inode_owner_or_capable(file_mnt_user_ns(filp), inode)) + return -EPERM; + + /* required for strict SunOS emulation */ + if (O_NONBLOCK != O_NDELAY) + if (arg & O_NDELAY) + arg |= O_NONBLOCK; + + /* Pipe packetized mode is controlled by O_DIRECT flag */ + if (!S_ISFIFO(inode->i_mode) && + (arg & O_DIRECT) && + !(filp->f_mode & FMODE_CAN_ODIRECT)) + return -EINVAL; + + if (filp->f_op->check_flags) + error = filp->f_op->check_flags(arg); + if (error) + return error; + + /* + * ->fasync() is responsible for setting the FASYNC bit. + */ + if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) { + error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); + if (error < 0) + goto out; + if (error > 0) + error = 0; + } + spin_lock(&filp->f_lock); + filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); + filp->f_iocb_flags = iocb_flags(filp); + spin_unlock(&filp->f_lock); + + out: + return error; +} + +static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, + int force) +{ + write_lock_irq(&filp->f_owner.lock); + if (force || !filp->f_owner.pid) { + put_pid(filp->f_owner.pid); + filp->f_owner.pid = get_pid(pid); + filp->f_owner.pid_type = type; + + if (pid) { + const struct cred *cred = current_cred(); + filp->f_owner.uid = cred->uid; + filp->f_owner.euid = cred->euid; + } + } + write_unlock_irq(&filp->f_owner.lock); +} + +void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, + int force) +{ + security_file_set_fowner(filp); + f_modown(filp, pid, type, force); +} +EXPORT_SYMBOL(__f_setown); + +int f_setown(struct file *filp, unsigned long arg, int force) +{ + enum pid_type type; + struct pid *pid = NULL; + int who = arg, ret = 0; + + type = PIDTYPE_TGID; + if (who < 0) { + /* avoid overflow below */ + if (who == INT_MIN) + return -EINVAL; + + type = PIDTYPE_PGID; + who = -who; + } + + rcu_read_lock(); + if (who) { + pid = find_vpid(who); + if (!pid) + ret = -ESRCH; + } + + if (!ret) + __f_setown(filp, pid, type, force); + rcu_read_unlock(); + + return ret; +} +EXPORT_SYMBOL(f_setown); + +void f_delown(struct file *filp) +{ + f_modown(filp, NULL, PIDTYPE_TGID, 1); +} + +pid_t f_getown(struct file *filp) +{ + pid_t pid = 0; + + read_lock_irq(&filp->f_owner.lock); + rcu_read_lock(); + if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) { + pid = pid_vnr(filp->f_owner.pid); + if (filp->f_owner.pid_type == PIDTYPE_PGID) + pid = -pid; + } + rcu_read_unlock(); + read_unlock_irq(&filp->f_owner.lock); + return pid; +} + +static int f_setown_ex(struct file *filp, unsigned long arg) +{ + struct f_owner_ex __user *owner_p = (void __user *)arg; + struct f_owner_ex owner; + struct pid *pid; + int type; + int ret; + + ret = copy_from_user(&owner, owner_p, sizeof(owner)); + if (ret) + return -EFAULT; + + switch (owner.type) { + case F_OWNER_TID: + type = PIDTYPE_PID; + break; + + case F_OWNER_PID: + type = PIDTYPE_TGID; + break; + + case F_OWNER_PGRP: + type = PIDTYPE_PGID; + break; + + default: + return -EINVAL; + } + + rcu_read_lock(); + pid = find_vpid(owner.pid); + if (owner.pid && !pid) + ret = -ESRCH; + else + __f_setown(filp, pid, type, 1); + rcu_read_unlock(); + + return ret; +} + +static int f_getown_ex(struct file *filp, unsigned long arg) +{ + struct f_owner_ex __user *owner_p = (void __user *)arg; + struct f_owner_ex owner = {}; + int ret = 0; + + read_lock_irq(&filp->f_owner.lock); + rcu_read_lock(); + if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) + owner.pid = pid_vnr(filp->f_owner.pid); + rcu_read_unlock(); + switch (filp->f_owner.pid_type) { + case PIDTYPE_PID: + owner.type = F_OWNER_TID; + break; + + case PIDTYPE_TGID: + owner.type = F_OWNER_PID; + break; + + case PIDTYPE_PGID: + owner.type = F_OWNER_PGRP; + break; + + default: + WARN_ON(1); + ret = -EINVAL; + break; + } + read_unlock_irq(&filp->f_owner.lock); + + if (!ret) { + ret = copy_to_user(owner_p, &owner, sizeof(owner)); + if (ret) + ret = -EFAULT; + } + return ret; +} + +#ifdef CONFIG_CHECKPOINT_RESTORE +static int f_getowner_uids(struct file *filp, unsigned long arg) +{ + struct user_namespace *user_ns = current_user_ns(); + uid_t __user *dst = (void __user *)arg; + uid_t src[2]; + int err; + + read_lock_irq(&filp->f_owner.lock); + src[0] = from_kuid(user_ns, filp->f_owner.uid); + src[1] = from_kuid(user_ns, filp->f_owner.euid); + read_unlock_irq(&filp->f_owner.lock); + + err = put_user(src[0], &dst[0]); + err |= put_user(src[1], &dst[1]); + + return err; +} +#else +static int f_getowner_uids(struct file *filp, unsigned long arg) +{ + return -EINVAL; +} +#endif + +static bool rw_hint_valid(enum rw_hint hint) +{ + switch (hint) { + case RWH_WRITE_LIFE_NOT_SET: + case RWH_WRITE_LIFE_NONE: + case RWH_WRITE_LIFE_SHORT: + case RWH_WRITE_LIFE_MEDIUM: + case RWH_WRITE_LIFE_LONG: + case RWH_WRITE_LIFE_EXTREME: + return true; + default: + return false; + } +} + +static long fcntl_rw_hint(struct file *file, unsigned int cmd, + unsigned long arg) +{ + struct inode *inode = file_inode(file); + u64 __user *argp = (u64 __user *)arg; + enum rw_hint hint; + u64 h; + + switch (cmd) { + case F_GET_RW_HINT: + h = inode->i_write_hint; + if (copy_to_user(argp, &h, sizeof(*argp))) + return -EFAULT; + return 0; + case F_SET_RW_HINT: + if (copy_from_user(&h, argp, sizeof(h))) + return -EFAULT; + hint = (enum rw_hint) h; + if (!rw_hint_valid(hint)) + return -EINVAL; + + inode_lock(inode); + inode->i_write_hint = hint; + inode_unlock(inode); + return 0; + default: + return -EINVAL; + } +} + +static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, + struct file *filp) +{ + void __user *argp = (void __user *)arg; + struct flock flock; + long err = -EINVAL; + + switch (cmd) { + case F_DUPFD: + err = f_dupfd(arg, filp, 0); + break; + case F_DUPFD_CLOEXEC: + err = f_dupfd(arg, filp, O_CLOEXEC); + break; + case F_GETFD: + err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; + break; + case F_SETFD: + err = 0; + set_close_on_exec(fd, arg & FD_CLOEXEC); + break; + case F_GETFL: + err = filp->f_flags; + break; + case F_SETFL: + err = setfl(fd, filp, arg); + break; +#if BITS_PER_LONG != 32 + /* 32-bit arches must use fcntl64() */ + case F_OFD_GETLK: +#endif + case F_GETLK: + if (copy_from_user(&flock, argp, sizeof(flock))) + return -EFAULT; + err = fcntl_getlk(filp, cmd, &flock); + if (!err && copy_to_user(argp, &flock, sizeof(flock))) + return -EFAULT; + break; +#if BITS_PER_LONG != 32 + /* 32-bit arches must use fcntl64() */ + case F_OFD_SETLK: + case F_OFD_SETLKW: + fallthrough; +#endif + case F_SETLK: + case F_SETLKW: + if (copy_from_user(&flock, argp, sizeof(flock))) + return -EFAULT; + err = fcntl_setlk(fd, filp, cmd, &flock); + break; + case F_GETOWN: + /* + * XXX If f_owner is a process group, the + * negative return value will get converted + * into an error. Oops. If we keep the + * current syscall conventions, the only way + * to fix this will be in libc. + */ + err = f_getown(filp); + force_successful_syscall_return(); + break; + case F_SETOWN: + err = f_setown(filp, arg, 1); + break; + case F_GETOWN_EX: + err = f_getown_ex(filp, arg); + break; + case F_SETOWN_EX: + err = f_setown_ex(filp, arg); + break; + case F_GETOWNER_UIDS: + err = f_getowner_uids(filp, arg); + break; + case F_GETSIG: + err = filp->f_owner.signum; + break; + case F_SETSIG: + /* arg == 0 restores default behaviour. */ + if (!valid_signal(arg)) { + break; + } + err = 0; + filp->f_owner.signum = arg; + break; + case F_GETLEASE: + err = fcntl_getlease(filp); + break; + case F_SETLEASE: + err = fcntl_setlease(fd, filp, arg); + break; + case F_NOTIFY: + err = fcntl_dirnotify(fd, filp, arg); + break; + case F_SETPIPE_SZ: + case F_GETPIPE_SZ: + err = pipe_fcntl(filp, cmd, arg); + break; + case F_ADD_SEALS: + case F_GET_SEALS: + err = memfd_fcntl(filp, cmd, arg); + break; + case F_GET_RW_HINT: + case F_SET_RW_HINT: + err = fcntl_rw_hint(filp, cmd, arg); + break; + default: + break; + } + return err; +} + +static int check_fcntl_cmd(unsigned cmd) +{ + switch (cmd) { + case F_DUPFD: + case F_DUPFD_CLOEXEC: + case F_GETFD: + case F_SETFD: + case F_GETFL: + return 1; + } + return 0; +} + +SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) +{ + struct fd f = fdget_raw(fd); + long err = -EBADF; + + if (!f.file) + goto out; + + if (unlikely(f.file->f_mode & FMODE_PATH)) { + if (!check_fcntl_cmd(cmd)) + goto out1; + } + + err = security_file_fcntl(f.file, cmd, arg); + if (!err) + err = do_fcntl(fd, cmd, arg, f.file); + +out1: + fdput(f); +out: + return err; +} + +#if BITS_PER_LONG == 32 +SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, + unsigned long, arg) +{ + void __user *argp = (void __user *)arg; + struct fd f = fdget_raw(fd); + struct flock64 flock; + long err = -EBADF; + + if (!f.file) + goto out; + + if (unlikely(f.file->f_mode & FMODE_PATH)) { + if (!check_fcntl_cmd(cmd)) + goto out1; + } + + err = security_file_fcntl(f.file, cmd, arg); + if (err) + goto out1; + + switch (cmd) { + case F_GETLK64: + case F_OFD_GETLK: + err = -EFAULT; + if (copy_from_user(&flock, argp, sizeof(flock))) + break; + err = fcntl_getlk64(f.file, cmd, &flock); + if (!err && copy_to_user(argp, &flock, sizeof(flock))) + err = -EFAULT; + break; + case F_SETLK64: + case F_SETLKW64: + case F_OFD_SETLK: + case F_OFD_SETLKW: + err = -EFAULT; + if (copy_from_user(&flock, argp, sizeof(flock))) + break; + err = fcntl_setlk64(fd, f.file, cmd, &flock); + break; + default: + err = do_fcntl(fd, cmd, arg, f.file); + break; + } +out1: + fdput(f); +out: + return err; +} +#endif + +#ifdef CONFIG_COMPAT +/* careful - don't use anywhere else */ +#define copy_flock_fields(dst, src) \ + (dst)->l_type = (src)->l_type; \ + (dst)->l_whence = (src)->l_whence; \ + (dst)->l_start = (src)->l_start; \ + (dst)->l_len = (src)->l_len; \ + (dst)->l_pid = (src)->l_pid; + +static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl) +{ + struct compat_flock fl; + + if (copy_from_user(&fl, ufl, sizeof(struct compat_flock))) + return -EFAULT; + copy_flock_fields(kfl, &fl); + return 0; +} + +static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl) +{ + struct compat_flock64 fl; + + if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64))) + return -EFAULT; + copy_flock_fields(kfl, &fl); + return 0; +} + +static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl) +{ + struct compat_flock fl; + + memset(&fl, 0, sizeof(struct compat_flock)); + copy_flock_fields(&fl, kfl); + if (copy_to_user(ufl, &fl, sizeof(struct compat_flock))) + return -EFAULT; + return 0; +} + +static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl) +{ + struct compat_flock64 fl; + + BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start)); + BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len)); + + memset(&fl, 0, sizeof(struct compat_flock64)); + copy_flock_fields(&fl, kfl); + if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64))) + return -EFAULT; + return 0; +} +#undef copy_flock_fields + +static unsigned int +convert_fcntl_cmd(unsigned int cmd) +{ + switch (cmd) { + case F_GETLK64: + return F_GETLK; + case F_SETLK64: + return F_SETLK; + case F_SETLKW64: + return F_SETLKW; + } + + return cmd; +} + +/* + * GETLK was successful and we need to return the data, but it needs to fit in + * the compat structure. + * l_start shouldn't be too big, unless the original start + end is greater than + * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return + * -EOVERFLOW in that case. l_len could be too big, in which case we just + * truncate it, and only allow the app to see that part of the conflicting lock + * that might make sense to it anyway + */ +static int fixup_compat_flock(struct flock *flock) +{ + if (flock->l_start > COMPAT_OFF_T_MAX) + return -EOVERFLOW; + if (flock->l_len > COMPAT_OFF_T_MAX) + flock->l_len = COMPAT_OFF_T_MAX; + return 0; +} + +static long do_compat_fcntl64(unsigned int fd, unsigned int cmd, + compat_ulong_t arg) +{ + struct fd f = fdget_raw(fd); + struct flock flock; + long err = -EBADF; + + if (!f.file) + return err; + + if (unlikely(f.file->f_mode & FMODE_PATH)) { + if (!check_fcntl_cmd(cmd)) + goto out_put; + } + + err = security_file_fcntl(f.file, cmd, arg); + if (err) + goto out_put; + + switch (cmd) { + case F_GETLK: + err = get_compat_flock(&flock, compat_ptr(arg)); + if (err) + break; + err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); + if (err) + break; + err = fixup_compat_flock(&flock); + if (!err) + err = put_compat_flock(&flock, compat_ptr(arg)); + break; + case F_GETLK64: + case F_OFD_GETLK: + err = get_compat_flock64(&flock, compat_ptr(arg)); + if (err) + break; + err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); + if (!err) + err = put_compat_flock64(&flock, compat_ptr(arg)); + break; + case F_SETLK: + case F_SETLKW: + err = get_compat_flock(&flock, compat_ptr(arg)); + if (err) + break; + err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); + break; + case F_SETLK64: + case F_SETLKW64: + case F_OFD_SETLK: + case F_OFD_SETLKW: + err = get_compat_flock64(&flock, compat_ptr(arg)); + if (err) + break; + err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); + break; + default: + err = do_fcntl(fd, cmd, arg, f.file); + break; + } +out_put: + fdput(f); + return err; +} + +COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, + compat_ulong_t, arg) +{ + return do_compat_fcntl64(fd, cmd, arg); +} + +COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, + compat_ulong_t, arg) +{ + switch (cmd) { + case F_GETLK64: + case F_SETLK64: + case F_SETLKW64: + case F_OFD_GETLK: + case F_OFD_SETLK: + case F_OFD_SETLKW: + return -EINVAL; + } + return do_compat_fcntl64(fd, cmd, arg); +} +#endif + +/* Table to convert sigio signal codes into poll band bitmaps */ + +static const __poll_t band_table[NSIGPOLL] = { + EPOLLIN | EPOLLRDNORM, /* POLL_IN */ + EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */ + EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */ + EPOLLERR, /* POLL_ERR */ + EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */ + EPOLLHUP | EPOLLERR /* POLL_HUP */ +}; + +static inline int sigio_perm(struct task_struct *p, + struct fown_struct *fown, int sig) +{ + const struct cred *cred; + int ret; + + rcu_read_lock(); + cred = __task_cred(p); + ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || + uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || + uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && + !security_file_send_sigiotask(p, fown, sig)); + rcu_read_unlock(); + return ret; +} + +static void send_sigio_to_task(struct task_struct *p, + struct fown_struct *fown, + int fd, int reason, enum pid_type type) +{ + /* + * F_SETSIG can change ->signum lockless in parallel, make + * sure we read it once and use the same value throughout. + */ + int signum = READ_ONCE(fown->signum); + + if (!sigio_perm(p, fown, signum)) + return; + + switch (signum) { + default: { + kernel_siginfo_t si; + + /* Queue a rt signal with the appropriate fd as its + value. We use SI_SIGIO as the source, not + SI_KERNEL, since kernel signals always get + delivered even if we can't queue. Failure to + queue in this case _should_ be reported; we fall + back to SIGIO in that case. --sct */ + clear_siginfo(&si); + si.si_signo = signum; + si.si_errno = 0; + si.si_code = reason; + /* + * Posix definies POLL_IN and friends to be signal + * specific si_codes for SIG_POLL. Linux extended + * these si_codes to other signals in a way that is + * ambiguous if other signals also have signal + * specific si_codes. In that case use SI_SIGIO instead + * to remove the ambiguity. + */ + if ((signum != SIGPOLL) && sig_specific_sicodes(signum)) + si.si_code = SI_SIGIO; + + /* Make sure we are called with one of the POLL_* + reasons, otherwise we could leak kernel stack into + userspace. */ + BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL)); + if (reason - POLL_IN >= NSIGPOLL) + si.si_band = ~0L; + else + si.si_band = mangle_poll(band_table[reason - POLL_IN]); + si.si_fd = fd; + if (!do_send_sig_info(signum, &si, p, type)) + break; + } + fallthrough; /* fall back on the old plain SIGIO signal */ + case 0: + do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type); + } +} + +void send_sigio(struct fown_struct *fown, int fd, int band) +{ + struct task_struct *p; + enum pid_type type; + unsigned long flags; + struct pid *pid; + + read_lock_irqsave(&fown->lock, flags); + + type = fown->pid_type; + pid = fown->pid; + if (!pid) + goto out_unlock_fown; + + if (type <= PIDTYPE_TGID) { + rcu_read_lock(); + p = pid_task(pid, PIDTYPE_PID); + if (p) + send_sigio_to_task(p, fown, fd, band, type); + rcu_read_unlock(); + } else { + read_lock(&tasklist_lock); + do_each_pid_task(pid, type, p) { + send_sigio_to_task(p, fown, fd, band, type); + } while_each_pid_task(pid, type, p); + read_unlock(&tasklist_lock); + } + out_unlock_fown: + read_unlock_irqrestore(&fown->lock, flags); +} + +static void send_sigurg_to_task(struct task_struct *p, + struct fown_struct *fown, enum pid_type type) +{ + if (sigio_perm(p, fown, SIGURG)) + do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type); +} + +int send_sigurg(struct fown_struct *fown) +{ + struct task_struct *p; + enum pid_type type; + struct pid *pid; + unsigned long flags; + int ret = 0; + + read_lock_irqsave(&fown->lock, flags); + + type = fown->pid_type; + pid = fown->pid; + if (!pid) + goto out_unlock_fown; + + ret = 1; + + if (type <= PIDTYPE_TGID) { + rcu_read_lock(); + p = pid_task(pid, PIDTYPE_PID); + if (p) + send_sigurg_to_task(p, fown, type); + rcu_read_unlock(); + } else { + read_lock(&tasklist_lock); + do_each_pid_task(pid, type, p) { + send_sigurg_to_task(p, fown, type); + } while_each_pid_task(pid, type, p); + read_unlock(&tasklist_lock); + } + out_unlock_fown: + read_unlock_irqrestore(&fown->lock, flags); + return ret; +} + +static DEFINE_SPINLOCK(fasync_lock); +static struct kmem_cache *fasync_cache __read_mostly; + +static void fasync_free_rcu(struct rcu_head *head) +{ + kmem_cache_free(fasync_cache, + container_of(head, struct fasync_struct, fa_rcu)); +} + +/* + * Remove a fasync entry. If successfully removed, return + * positive and clear the FASYNC flag. If no entry exists, + * do nothing and return 0. + * + * NOTE! It is very important that the FASYNC flag always + * match the state "is the filp on a fasync list". + * + */ +int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) +{ + struct fasync_struct *fa, **fp; + int result = 0; + + spin_lock(&filp->f_lock); + spin_lock(&fasync_lock); + for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { + if (fa->fa_file != filp) + continue; + + write_lock_irq(&fa->fa_lock); + fa->fa_file = NULL; + write_unlock_irq(&fa->fa_lock); + + *fp = fa->fa_next; + call_rcu(&fa->fa_rcu, fasync_free_rcu); + filp->f_flags &= ~FASYNC; + result = 1; + break; + } + spin_unlock(&fasync_lock); + spin_unlock(&filp->f_lock); + return result; +} + +struct fasync_struct *fasync_alloc(void) +{ + return kmem_cache_alloc(fasync_cache, GFP_KERNEL); +} + +/* + * NOTE! This can be used only for unused fasync entries: + * entries that actually got inserted on the fasync list + * need to be released by rcu - see fasync_remove_entry. + */ +void fasync_free(struct fasync_struct *new) +{ + kmem_cache_free(fasync_cache, new); +} + +/* + * Insert a new entry into the fasync list. Return the pointer to the + * old one if we didn't use the new one. + * + * NOTE! It is very important that the FASYNC flag always + * match the state "is the filp on a fasync list". + */ +struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) +{ + struct fasync_struct *fa, **fp; + + spin_lock(&filp->f_lock); + spin_lock(&fasync_lock); + for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { + if (fa->fa_file != filp) + continue; + + write_lock_irq(&fa->fa_lock); + fa->fa_fd = fd; + write_unlock_irq(&fa->fa_lock); + goto out; + } + + rwlock_init(&new->fa_lock); + new->magic = FASYNC_MAGIC; + new->fa_file = filp; + new->fa_fd = fd; + new->fa_next = *fapp; + rcu_assign_pointer(*fapp, new); + filp->f_flags |= FASYNC; + +out: + spin_unlock(&fasync_lock); + spin_unlock(&filp->f_lock); + return fa; +} + +/* + * Add a fasync entry. Return negative on error, positive if + * added, and zero if did nothing but change an existing one. + */ +static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) +{ + struct fasync_struct *new; + + new = fasync_alloc(); + if (!new) + return -ENOMEM; + + /* + * fasync_insert_entry() returns the old (update) entry if + * it existed. + * + * So free the (unused) new entry and return 0 to let the + * caller know that we didn't add any new fasync entries. + */ + if (fasync_insert_entry(fd, filp, fapp, new)) { + fasync_free(new); + return 0; + } + + return 1; +} + +/* + * fasync_helper() is used by almost all character device drivers + * to set up the fasync queue, and for regular files by the file + * lease code. It returns negative on error, 0 if it did no changes + * and positive if it added/deleted the entry. + */ +int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) +{ + if (!on) + return fasync_remove_entry(filp, fapp); + return fasync_add_entry(fd, filp, fapp); +} + +EXPORT_SYMBOL(fasync_helper); + +/* + * rcu_read_lock() is held + */ +static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) +{ + while (fa) { + struct fown_struct *fown; + unsigned long flags; + + if (fa->magic != FASYNC_MAGIC) { + printk(KERN_ERR "kill_fasync: bad magic number in " + "fasync_struct!\n"); + return; + } + read_lock_irqsave(&fa->fa_lock, flags); + if (fa->fa_file) { + fown = &fa->fa_file->f_owner; + /* Don't send SIGURG to processes which have not set a + queued signum: SIGURG has its own default signalling + mechanism. */ + if (!(sig == SIGURG && fown->signum == 0)) + send_sigio(fown, fa->fa_fd, band); + } + read_unlock_irqrestore(&fa->fa_lock, flags); + fa = rcu_dereference(fa->fa_next); + } +} + +void kill_fasync(struct fasync_struct **fp, int sig, int band) +{ + /* First a quick test without locking: usually + * the list is empty. + */ + if (*fp) { + rcu_read_lock(); + kill_fasync_rcu(rcu_dereference(*fp), sig, band); + rcu_read_unlock(); + } +} +EXPORT_SYMBOL(kill_fasync); + +static int __init fcntl_init(void) +{ + /* + * Please add new bits here to ensure allocation uniqueness. + * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY + * is defined as O_NONBLOCK on some platforms and not on others. + */ + BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != + HWEIGHT32( + (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | + __FMODE_EXEC | __FMODE_NONOTIFY)); + + fasync_cache = kmem_cache_create("fasync_cache", + sizeof(struct fasync_struct), 0, + SLAB_PANIC | SLAB_ACCOUNT, NULL); + return 0; +} + +module_init(fcntl_init) |