From 76cb841cb886eef6b3bee341a2266c76578724ad Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 6 May 2024 03:02:30 +0200 Subject: Adding upstream version 4.19.249. Signed-off-by: Daniel Baumann --- fs/proc/inode.c | 537 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 537 insertions(+) create mode 100644 fs/proc/inode.c (limited to 'fs/proc/inode.c') diff --git a/fs/proc/inode.c b/fs/proc/inode.c new file mode 100644 index 000000000..31bf3bb8d --- /dev/null +++ b/fs/proc/inode.c @@ -0,0 +1,537 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/proc/inode.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "internal.h" + +static void proc_evict_inode(struct inode *inode) +{ + struct proc_dir_entry *de; + struct ctl_table_header *head; + + truncate_inode_pages_final(&inode->i_data); + clear_inode(inode); + + /* Stop tracking associated processes */ + put_pid(PROC_I(inode)->pid); + + /* Let go of any associated proc directory entry */ + de = PDE(inode); + if (de) + pde_put(de); + + head = PROC_I(inode)->sysctl; + if (head) { + RCU_INIT_POINTER(PROC_I(inode)->sysctl, NULL); + proc_sys_evict_inode(inode, head); + } +} + +static struct kmem_cache *proc_inode_cachep __ro_after_init; +static struct kmem_cache *pde_opener_cache __ro_after_init; + +static struct inode *proc_alloc_inode(struct super_block *sb) +{ + struct proc_inode *ei; + struct inode *inode; + + ei = kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL); + if (!ei) + return NULL; + ei->pid = NULL; + ei->fd = 0; + ei->op.proc_get_link = NULL; + ei->pde = NULL; + ei->sysctl = NULL; + ei->sysctl_entry = NULL; + ei->ns_ops = NULL; + inode = &ei->vfs_inode; + return inode; +} + +static void proc_i_callback(struct rcu_head *head) +{ + struct inode *inode = container_of(head, struct inode, i_rcu); + kmem_cache_free(proc_inode_cachep, PROC_I(inode)); +} + +static void proc_destroy_inode(struct inode *inode) +{ + call_rcu(&inode->i_rcu, proc_i_callback); +} + +static void init_once(void *foo) +{ + struct proc_inode *ei = (struct proc_inode *) foo; + + inode_init_once(&ei->vfs_inode); +} + +void __init proc_init_kmemcache(void) +{ + proc_inode_cachep = kmem_cache_create("proc_inode_cache", + sizeof(struct proc_inode), + 0, (SLAB_RECLAIM_ACCOUNT| + SLAB_MEM_SPREAD|SLAB_ACCOUNT| + SLAB_PANIC), + init_once); + pde_opener_cache = + kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0, + SLAB_ACCOUNT|SLAB_PANIC, NULL); + proc_dir_entry_cache = kmem_cache_create_usercopy( + "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC, + offsetof(struct proc_dir_entry, inline_name), + SIZEOF_PDE_INLINE_NAME, NULL); + BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE); +} + +static int proc_show_options(struct seq_file *seq, struct dentry *root) +{ + struct super_block *sb = root->d_sb; + struct pid_namespace *pid = sb->s_fs_info; + + if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID)) + seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid)); + if (pid->hide_pid != HIDEPID_OFF) + seq_printf(seq, ",hidepid=%u", pid->hide_pid); + + return 0; +} + +static const struct super_operations proc_sops = { + .alloc_inode = proc_alloc_inode, + .destroy_inode = proc_destroy_inode, + .drop_inode = generic_delete_inode, + .evict_inode = proc_evict_inode, + .statfs = simple_statfs, + .remount_fs = proc_remount, + .show_options = proc_show_options, +}; + +enum {BIAS = -1U<<31}; + +static inline int use_pde(struct proc_dir_entry *pde) +{ + return likely(atomic_inc_unless_negative(&pde->in_use)); +} + +static void unuse_pde(struct proc_dir_entry *pde) +{ + if (unlikely(atomic_dec_return(&pde->in_use) == BIAS)) + complete(pde->pde_unload_completion); +} + +/* pde is locked on entry, unlocked on exit */ +static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo) +{ + /* + * close() (proc_reg_release()) can't delete an entry and proceed: + * ->release hook needs to be available at the right moment. + * + * rmmod (remove_proc_entry() et al) can't delete an entry and proceed: + * "struct file" needs to be available at the right moment. + * + * Therefore, first process to enter this function does ->release() and + * signals its completion to the other process which does nothing. + */ + if (pdeo->closing) { + /* somebody else is doing that, just wait */ + DECLARE_COMPLETION_ONSTACK(c); + pdeo->c = &c; + spin_unlock(&pde->pde_unload_lock); + wait_for_completion(&c); + } else { + struct file *file; + struct completion *c; + + pdeo->closing = true; + spin_unlock(&pde->pde_unload_lock); + file = pdeo->file; + pde->proc_fops->release(file_inode(file), file); + spin_lock(&pde->pde_unload_lock); + /* After ->release. */ + list_del(&pdeo->lh); + c = pdeo->c; + spin_unlock(&pde->pde_unload_lock); + if (unlikely(c)) + complete(c); + kmem_cache_free(pde_opener_cache, pdeo); + } +} + +void proc_entry_rundown(struct proc_dir_entry *de) +{ + DECLARE_COMPLETION_ONSTACK(c); + /* Wait until all existing callers into module are done. */ + de->pde_unload_completion = &c; + if (atomic_add_return(BIAS, &de->in_use) != BIAS) + wait_for_completion(&c); + + /* ->pde_openers list can't grow from now on. */ + + spin_lock(&de->pde_unload_lock); + while (!list_empty(&de->pde_openers)) { + struct pde_opener *pdeo; + pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh); + close_pdeo(de, pdeo); + spin_lock(&de->pde_unload_lock); + } + spin_unlock(&de->pde_unload_lock); +} + +static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + loff_t rv = -EINVAL; + if (use_pde(pde)) { + loff_t (*llseek)(struct file *, loff_t, int); + llseek = pde->proc_fops->llseek; + if (!llseek) + llseek = default_llseek; + rv = llseek(file, offset, whence); + unuse_pde(pde); + } + return rv; +} + +static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) +{ + ssize_t (*read)(struct file *, char __user *, size_t, loff_t *); + struct proc_dir_entry *pde = PDE(file_inode(file)); + ssize_t rv = -EIO; + if (use_pde(pde)) { + read = pde->proc_fops->read; + if (read) + rv = read(file, buf, count, ppos); + unuse_pde(pde); + } + return rv; +} + +static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) +{ + ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *); + struct proc_dir_entry *pde = PDE(file_inode(file)); + ssize_t rv = -EIO; + if (use_pde(pde)) { + write = pde->proc_fops->write; + if (write) + rv = write(file, buf, count, ppos); + unuse_pde(pde); + } + return rv; +} + +static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + __poll_t rv = DEFAULT_POLLMASK; + __poll_t (*poll)(struct file *, struct poll_table_struct *); + if (use_pde(pde)) { + poll = pde->proc_fops->poll; + if (poll) + rv = poll(file, pts); + unuse_pde(pde); + } + return rv; +} + +static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + long rv = -ENOTTY; + long (*ioctl)(struct file *, unsigned int, unsigned long); + if (use_pde(pde)) { + ioctl = pde->proc_fops->unlocked_ioctl; + if (ioctl) + rv = ioctl(file, cmd, arg); + unuse_pde(pde); + } + return rv; +} + +#ifdef CONFIG_COMPAT +static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + long rv = -ENOTTY; + long (*compat_ioctl)(struct file *, unsigned int, unsigned long); + if (use_pde(pde)) { + compat_ioctl = pde->proc_fops->compat_ioctl; + if (compat_ioctl) + rv = compat_ioctl(file, cmd, arg); + unuse_pde(pde); + } + return rv; +} +#endif + +static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + int rv = -EIO; + int (*mmap)(struct file *, struct vm_area_struct *); + if (use_pde(pde)) { + mmap = pde->proc_fops->mmap; + if (mmap) + rv = mmap(file, vma); + unuse_pde(pde); + } + return rv; +} + +static unsigned long +proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, + unsigned long len, unsigned long pgoff, + unsigned long flags) +{ + struct proc_dir_entry *pde = PDE(file_inode(file)); + unsigned long rv = -EIO; + + if (use_pde(pde)) { + typeof(proc_reg_get_unmapped_area) *get_area; + + get_area = pde->proc_fops->get_unmapped_area; +#ifdef CONFIG_MMU + if (!get_area) + get_area = current->mm->get_unmapped_area; +#endif + + if (get_area) + rv = get_area(file, orig_addr, len, pgoff, flags); + else + rv = orig_addr; + unuse_pde(pde); + } + return rv; +} + +static int proc_reg_open(struct inode *inode, struct file *file) +{ + struct proc_dir_entry *pde = PDE(inode); + int rv = 0; + int (*open)(struct inode *, struct file *); + int (*release)(struct inode *, struct file *); + struct pde_opener *pdeo; + + /* + * Ensure that + * 1) PDE's ->release hook will be called no matter what + * either normally by close()/->release, or forcefully by + * rmmod/remove_proc_entry. + * + * 2) rmmod isn't blocked by opening file in /proc and sitting on + * the descriptor (including "rmmod foo release hook. + */ + if (!use_pde(pde)) + return -ENOENT; + + release = pde->proc_fops->release; + if (release) { + pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL); + if (!pdeo) { + rv = -ENOMEM; + goto out_unuse; + } + } + + open = pde->proc_fops->open; + if (open) + rv = open(inode, file); + + if (release) { + if (rv == 0) { + /* To know what to release. */ + pdeo->file = file; + pdeo->closing = false; + pdeo->c = NULL; + spin_lock(&pde->pde_unload_lock); + list_add(&pdeo->lh, &pde->pde_openers); + spin_unlock(&pde->pde_unload_lock); + } else + kmem_cache_free(pde_opener_cache, pdeo); + } + +out_unuse: + unuse_pde(pde); + return rv; +} + +static int proc_reg_release(struct inode *inode, struct file *file) +{ + struct proc_dir_entry *pde = PDE(inode); + struct pde_opener *pdeo; + spin_lock(&pde->pde_unload_lock); + list_for_each_entry(pdeo, &pde->pde_openers, lh) { + if (pdeo->file == file) { + close_pdeo(pde, pdeo); + return 0; + } + } + spin_unlock(&pde->pde_unload_lock); + return 0; +} + +static const struct file_operations proc_reg_file_ops = { + .llseek = proc_reg_llseek, + .read = proc_reg_read, + .write = proc_reg_write, + .poll = proc_reg_poll, + .unlocked_ioctl = proc_reg_unlocked_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = proc_reg_compat_ioctl, +#endif + .mmap = proc_reg_mmap, + .get_unmapped_area = proc_reg_get_unmapped_area, + .open = proc_reg_open, + .release = proc_reg_release, +}; + +#ifdef CONFIG_COMPAT +static const struct file_operations proc_reg_file_ops_no_compat = { + .llseek = proc_reg_llseek, + .read = proc_reg_read, + .write = proc_reg_write, + .poll = proc_reg_poll, + .unlocked_ioctl = proc_reg_unlocked_ioctl, + .mmap = proc_reg_mmap, + .get_unmapped_area = proc_reg_get_unmapped_area, + .open = proc_reg_open, + .release = proc_reg_release, +}; +#endif + +static void proc_put_link(void *p) +{ + unuse_pde(p); +} + +static const char *proc_get_link(struct dentry *dentry, + struct inode *inode, + struct delayed_call *done) +{ + struct proc_dir_entry *pde = PDE(inode); + if (!use_pde(pde)) + return ERR_PTR(-EINVAL); + set_delayed_call(done, proc_put_link, pde); + return pde->data; +} + +const struct inode_operations proc_link_inode_operations = { + .get_link = proc_get_link, +}; + +struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) +{ + struct inode *inode = new_inode(sb); + + if (inode) { + inode->i_ino = de->low_ino; + inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); + PROC_I(inode)->pde = de; + + if (is_empty_pde(de)) { + make_empty_dir_inode(inode); + return inode; + } + if (de->mode) { + inode->i_mode = de->mode; + inode->i_uid = de->uid; + inode->i_gid = de->gid; + } + if (de->size) + inode->i_size = de->size; + if (de->nlink) + set_nlink(inode, de->nlink); + WARN_ON(!de->proc_iops); + inode->i_op = de->proc_iops; + if (de->proc_fops) { + if (S_ISREG(inode->i_mode)) { +#ifdef CONFIG_COMPAT + if (!de->proc_fops->compat_ioctl) + inode->i_fop = + &proc_reg_file_ops_no_compat; + else +#endif + inode->i_fop = &proc_reg_file_ops; + } else { + inode->i_fop = de->proc_fops; + } + } + } else + pde_put(de); + return inode; +} + +int proc_fill_super(struct super_block *s, void *data, int silent) +{ + struct pid_namespace *ns = get_pid_ns(s->s_fs_info); + struct inode *root_inode; + int ret; + + if (!proc_parse_options(data, ns)) + return -EINVAL; + + /* User space would break if executables or devices appear on proc */ + s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV; + s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC; + s->s_blocksize = 1024; + s->s_blocksize_bits = 10; + s->s_magic = PROC_SUPER_MAGIC; + s->s_op = &proc_sops; + s->s_time_gran = 1; + + /* + * procfs isn't actually a stacking filesystem; however, there is + * too much magic going on inside it to permit stacking things on + * top of it + */ + s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH; + + pde_get(&proc_root); + root_inode = proc_get_inode(s, &proc_root); + if (!root_inode) { + pr_err("proc_fill_super: get root inode failed\n"); + return -ENOMEM; + } + + s->s_root = d_make_root(root_inode); + if (!s->s_root) { + pr_err("proc_fill_super: allocate dentry failed\n"); + return -ENOMEM; + } + + ret = proc_setup_self(s); + if (ret) { + return ret; + } + return proc_setup_thread_self(s); +} -- cgit v1.2.3