// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/proc/inode.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/cache.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/pid_namespace.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/completion.h>
#include <linux/poll.h>
#include <linux/printk.h>
#include <linux/file.h>
#include <linux/limits.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/bug.h>
#include "internal.h"
static void proc_evict_inode(struct inode *inode)
{
struct ctl_table_header *head;
struct proc_inode *ei = PROC_I(inode);
truncate_inode_pages_final(&inode->i_data);
clear_inode(inode);
/* Stop tracking associated processes */
if (ei->pid)
proc_pid_evict_inode(ei);
head = ei->sysctl;
if (head) {
RCU_INIT_POINTER(ei->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;
ei = alloc_inode_sb(sb, 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;
INIT_HLIST_NODE(&ei->sibling_inodes);
ei->ns_ops = NULL;
return &ei->vfs_inode;
}
static void proc_free_inode(struct inode *inode)
{
struct proc_inode *ei = PROC_I(inode);
if (ei->pid)
put_pid(ei->pid);
/* Let go of any associated proc directory entry */
if (ei->pde)
pde_put(ei->pde);
kmem_cache_free(proc_inode_cachep, PROC_I(inode));
}
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_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);
}
void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
{
struct hlist_node *node;
struct super_block *old_sb = NULL;
rcu_read_lock();
while ((node = hlist_first_rcu(inodes))) {
struct proc_inode *ei = hlist_entry(node, struct proc_inode, sibling_inodes);
struct super_block *sb;
struct inode *inode;
spin_lock(lock);
hlist_del_init_rcu(&ei->sibling_inodes);
spin_unlock(lock);
inode = &ei->vfs_inode;
sb = inode->i_sb;
if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
continue;
inode = igrab(inode);
rcu_read_unlock();
if (sb != old_sb) {
if (old_sb)
deactivate_super(old_sb);
old_sb = sb;
}
if (unlikely(!inode)) {
rcu_read_lock();
continue;
}
if (S_ISDIR(inode->i_mode)) {
struct dentry *dir = d_find_any_alias(inode);
if (dir) {
d_invalidate(dir);
dput(dir);
}
} else {
struct dentry *dentry;
while ((dentry = d_find_alias(inode))) {
d_invalidate(dentry);
dput(dentry);
}
}
iput(inode);
rcu_read_lock();
}
rcu_read_unlock();
if (old_sb)
deactivate_super(old_sb);
}
static inline const char *hidepid2str(enum proc_hidepid v)
{
switch (v) {
case HIDEPID_OFF: return "off";
case HIDEPID_NO_ACCESS: return "noaccess";
case HIDEPID_INVISIBLE: return "invisible";
case HIDEPID_NOT_PTRACEABLE: return "ptraceable";
}
WARN_ONCE(1, "bad hide_pid value: %d\n", v);
return "unknown";
}
static int proc_show_options(struct seq_file *seq, struct dentry *root)
{
struct proc_fs_info *fs_info = proc_sb_info(root->d_sb);
if (!gid_eq(fs_info->pid_gid, GLOBAL_ROOT_GID))
seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, fs_info->pid_gid));
if (fs_info->hide_pid != HIDEPID_OFF)
seq_printf(seq, ",hidepid=%s", hidepid2str(fs_info->hide_pid));
if (fs_info->pidonly != PROC_PIDONLY_OFF)
seq_printf(seq, ",subset=pid");
return 0;
}
const struct super_operations proc_sops = {
.alloc_inode = proc_alloc_inode,
.free_inode = proc_free_inode,
.drop_inode = generic_delete_inode,
.evict_inode = proc_evict_inode,
.statfs = simple_statfs,
.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);
}
/*
* At most 2 contexts can enter this function: the one doing the last
* close on the descriptor and whoever is deleting PDE itself.
*
* First to enter calls ->proc_release hook and signals its completion
* to the second one which waits and then does nothing.
*
* PDE is locked on entry, unlocked on exit.
*/
static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
__releases(&pde->pde_unload_lock)
{
/*
* 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.
*/
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_ops->proc_release(file_inode(file), file);
spin_lock(&pde->pde_unload_lock);
/* Strictly after ->proc_release, see above. */
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 (pde_is_permanent(pde)) {
return pde->proc_ops->proc_lseek(file, offset, whence);
} else if (use_pde(pde)) {
rv = pde->proc_ops->proc_lseek(file, offset, whence);
unuse_pde(pde);
}
return rv;
}
static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp));
ssize_t ret;
if (pde_is_permanent(pde))
return pde->proc_ops->proc_read_iter(iocb, iter);
if (!use_pde(pde))
return -EIO;
ret = pde->proc_ops->proc_read_iter(iocb, iter);
unuse_pde(pde);
return ret;
}
static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
__auto_type read = pde->proc_ops->proc_read;
if (read)
return read(file, buf, count, ppos);
return -EIO;
}
static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
ssize_t rv = -EIO;
if (pde_is_permanent(pde)) {
return pde_read(pde, file, buf, count, ppos);
} else if (use_pde(pde)) {
rv = pde_read(pde, file, buf, count, ppos);
unuse_pde(pde);
}
return rv;
}
static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
__auto_type write = pde->proc_ops->proc_write;
if (write)
return write(file, buf, count, ppos);
return -EIO;
}
static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
ssize_t rv = -EIO;
if (pde_is_permanent(pde)) {
return pde_write(pde, file, buf, count, ppos);
} else if (use_pde(pde)) {
rv = pde_write(pde, file, buf, count, ppos);
unuse_pde(pde);
}
return rv;
}
static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
{
__auto_type poll = pde->proc_ops->proc_poll;
if (poll)
return poll(file, pts);
return DEFAULT_POLLMASK;
}
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;
if (pde_is_permanent(pde)) {
return pde_poll(pde, file, pts);
} else if (use_pde(pde)) {
rv = pde_poll(pde, file, pts);
unuse_pde(pde);
}
return rv;
}
static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
{
__auto_type ioctl = pde->proc_ops->proc_ioctl;
if (ioctl)
return ioctl(file, cmd, arg);
return -ENOTTY;
}
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;
if (pde_is_permanent(pde)) {
return pde_ioctl(pde, file, cmd, arg);
} else if (use_pde(pde)) {
rv = pde_ioctl(pde, file, cmd, arg);
unuse_pde(pde);
}
return rv;
}
#ifdef CONFIG_COMPAT
static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
{
__auto_type compat_ioctl = pde->proc_ops->proc_compat_ioctl;
if (compat_ioctl)
return compat_ioctl(file, cmd, arg);
return -ENOTTY;
}
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;
if (pde_is_permanent(pde)) {
return pde_compat_ioctl(pde, file, cmd, arg);
} else if (use_pde(pde)) {
rv = pde_compat_ioctl(pde, file, cmd, arg);
unuse_pde(pde);
}
return rv;
}
#endif
static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
{
__auto_type mmap = pde->proc_ops->proc_mmap;
if (mmap)
return mmap(file, vma);
return -EIO;
}
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;
if (pde_is_permanent(pde)) {
return pde_mmap(pde, file, vma);
} else if (use_pde(pde)) {
rv = pde_mmap(pde, file, vma);
unuse_pde(pde);
}
return rv;
}
static unsigned long
pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
unsigned long len, unsigned long pgoff,
unsigned long flags)
{
if (pde->proc_ops->proc_get_unmapped_area)
return pde->proc_ops->proc_get_unmapped_area(file, orig_addr, len, pgoff, flags);
#ifdef CONFIG_MMU
return mm_get_unmapped_area(current->mm, file, orig_addr, len, pgoff, flags);
#endif
return orig_addr;
}
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 (pde_is_permanent(pde)) {
return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
} else if (use_pde(pde)) {
rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
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;
typeof_member(struct proc_ops, proc_open) open;
struct pde_opener *pdeo;
if (!pde->proc_ops->proc_lseek)
file->f_mode &= ~FMODE_LSEEK;
if (pde_is_permanent(pde)) {
open = pde->proc_ops->proc_open;
if (open)
rv = open(inode, file);
return rv;
}
/*
* 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 </proc/foo" scenario).
*
* Save every "struct file" with custom ->release hook.
*/
if (!use_pde(pde))
return -ENOENT;
__auto_type release = pde->proc_ops->proc_release;
if (release) {
pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
if (!pdeo) {
rv = -ENOMEM;
goto out_unuse;
}
}
open = pde->proc_ops->proc_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;
if (pde_is_permanent(pde)) {
__auto_type release = pde->proc_ops->proc_release;
if (release) {
return release(inode, file);
}
return 0;
}
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,
.mmap = proc_reg_mmap,
.get_unmapped_area = proc_reg_get_unmapped_area,
.open = proc_reg_open,
.release = proc_reg_release,
};
static const struct file_operations proc_iter_file_ops = {
.llseek = proc_reg_llseek,
.read_iter = proc_reg_read_iter,
.write = proc_reg_write,
.splice_read = copy_splice_read,
.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,
};
#ifdef CONFIG_COMPAT
static const struct file_operations proc_reg_file_ops_compat = {
.llseek = proc_reg_llseek,
.read = proc_reg_read,
.write = proc_reg_write,
.poll = proc_reg_poll,
.unlocked_ioctl = proc_reg_unlocked_ioctl,
.compat_ioctl = proc_reg_compat_ioctl,
.mmap = proc_reg_mmap,
.get_unmapped_area = proc_reg_get_unmapped_area,
.open = proc_reg_open,
.release = proc_reg_release,
};
static const struct file_operations proc_iter_file_ops_compat = {
.llseek = proc_reg_llseek,
.read_iter = proc_reg_read_iter,
.splice_read = copy_splice_read,
.write = proc_reg_write,
.poll = proc_reg_poll,
.unlocked_ioctl = proc_reg_unlocked_ioctl,
.compat_ioctl = proc_reg_compat_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) {
pde_put(de);
return NULL;
}
inode->i_private = de->data;
inode->i_ino = de->low_ino;
simple_inode_init_ts(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);
if (S_ISREG(inode->i_mode)) {
inode->i_op = de->proc_iops;
if (de->proc_ops->proc_read_iter)
inode->i_fop = &proc_iter_file_ops;
else
inode->i_fop = &proc_reg_file_ops;
#ifdef CONFIG_COMPAT
if (de->proc_ops->proc_compat_ioctl) {
if (de->proc_ops->proc_read_iter)
inode->i_fop = &proc_iter_file_ops_compat;
else
inode->i_fop = &proc_reg_file_ops_compat;
}
#endif
} else if (S_ISDIR(inode->i_mode)) {
inode->i_op = de->proc_iops;
inode->i_fop = de->proc_dir_ops;
} else if (S_ISLNK(inode->i_mode)) {
inode->i_op = de->proc_iops;
inode->i_fop = NULL;
} else {
BUG();
}
return inode;
}
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