// SPDX-License-Identifier: GPL-2.0
#include <linux/sched/signal.h>
#include <linux/errno.h>
#include <linux/dcache.h>
#include <linux/path.h>
#include <linux/fdtable.h>
#include <linux/namei.h>
#include <linux/pid.h>
#include <linux/ptrace.h>
#include <linux/bitmap.h>
#include <linux/security.h>
#include <linux/file.h>
#include <linux/seq_file.h>
#include <linux/fs.h>
#include <linux/filelock.h>
#include <linux/proc_fs.h>
#include "../mount.h"
#include "internal.h"
#include "fd.h"
static int seq_show(struct seq_file *m, void *v)
{
struct files_struct *files = NULL;
int f_flags = 0, ret = -ENOENT;
struct file *file = NULL;
struct task_struct *task;
task = get_proc_task(m->private);
if (!task)
return -ENOENT;
task_lock(task);
files = task->files;
if (files) {
unsigned int fd = proc_fd(m->private);
spin_lock(&files->file_lock);
file = files_lookup_fd_locked(files, fd);
if (file) {
f_flags = file->f_flags;
if (close_on_exec(fd, files))
f_flags |= O_CLOEXEC;
get_file(file);
ret = 0;
}
spin_unlock(&files->file_lock);
}
task_unlock(task);
put_task_struct(task);
if (ret)
return ret;
seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n",
(long long)file->f_pos, f_flags,
real_mount(file->f_path.mnt)->mnt_id,
file_inode(file)->i_ino);
/* show_fd_locks() never dereferences files, so a stale value is safe */
show_fd_locks(m, file, files);
if (seq_has_overflowed(m))
goto out;
if (file->f_op->show_fdinfo)
file->f_op->show_fdinfo(m, file);
out:
fput(file);
return 0;
}
static int seq_fdinfo_open(struct inode *inode, struct file *file)
{
return single_open(file, seq_show, inode);
}
/**
* Shared /proc/pid/fdinfo and /proc/pid/fdinfo/fd permission helper to ensure
* that the current task has PTRACE_MODE_READ in addition to the normal
* POSIX-like checks.
*/
static int proc_fdinfo_permission(struct mnt_idmap *idmap, struct inode *inode,
int mask)
{
bool allowed = false;
struct task_struct *task = get_proc_task(inode);
if (!task)
return -ESRCH;
allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
put_task_struct(task);
if (!allowed)
return -EACCES;
return generic_permission(idmap, inode, mask);
}
static const struct inode_operations proc_fdinfo_file_inode_operations = {
.permission = proc_fdinfo_permission,
.setattr = proc_setattr,
};
static const struct file_operations proc_fdinfo_file_operations = {
.open = seq_fdinfo_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
{
struct file *file;
rcu_read_lock();
file = task_lookup_fdget_rcu(task, fd);
rcu_read_unlock();
if (file) {
*mode = file->f_mode;
fput(file);
}
return !!file;
}
static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
fmode_t f_mode)
{
task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
if (S_ISLNK(inode->i_mode)) {
unsigned i_mode = S_IFLNK;
if (f_mode & FMODE_READ)
i_mode |= S_IRUSR | S_IXUSR;
if (f_mode & FMODE_WRITE)
i_mode |= S_IWUSR | S_IXUSR;
inode->i_mode = i_mode;
}
security_task_to_inode(task, inode);
}
static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
{
struct task_struct *task;
struct inode *inode;
unsigned int fd;
if (flags & LOOKUP_RCU)
return -ECHILD;
inode = d_inode(dentry);
task = get_proc_task(inode);
fd = proc_fd(inode);
if (task) {
fmode_t f_mode;
if (tid_fd_mode(task, fd, &f_mode)) {
tid_fd_update_inode(task, inode, f_mode);
put_task_struct(task);
return 1;
}
put_task_struct(task);
}
return 0;
}
static const struct dentry_operations tid_fd_dentry_operations = {
.d_revalidate = tid_fd_revalidate,
.d_delete = pid_delete_dentry,
};
static int proc_fd_link(struct dentry *dentry, struct path *path)
{
struct task_struct *task;
int ret = -ENOENT;
task = get_proc_task(d_inode(dentry));
if (task) {
unsigned int fd = proc_fd(d_inode(dentry));
struct file *fd_file;
fd_file = fget_task(task, fd);
if (fd_file) {
*path = fd_file->f_path;
path_get(&fd_file->f_path);
ret = 0;
fput(fd_file);
}
put_task_struct(task);
}
return ret;
}
struct fd_data {
fmode_t mode;
unsigned fd;
};
static struct dentry *proc_fd_instantiate(struct dentry *dentry,
struct task_struct *task, const void *ptr)
{
const struct fd_data *data = ptr;
struct proc_inode *ei;
struct inode *inode;
inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
if (!inode)
return ERR_PTR(-ENOENT);
ei = PROC_I(inode);
ei->fd = data->fd;
inode->i_op = &proc_pid_link_inode_operations;
inode->i_size = 64;
ei->op.proc_get_link = proc_fd_link;
tid_fd_update_inode(task, inode, data->mode);
return proc_splice_unmountable(inode, dentry,
&tid_fd_dentry_operations);
}
static struct dentry *proc_lookupfd_common(struct inode *dir,
struct dentry *dentry,
instantiate_t instantiate)
{
struct task_struct *task = get_proc_task(dir);
struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
struct dentry *result = ERR_PTR(-ENOENT);
if (!task)
goto out_no_task;
if (data.fd == ~0U)
goto out;
if (!tid_fd_mode(task, data.fd, &data.mode))
goto out;
result = instantiate(dentry, task, &data);
out:
put_task_struct(task);
out_no_task:
return result;
}
static int proc_readfd_common(struct file *file, struct dir_context *ctx,
instantiate_t instantiate)
{
struct task_struct *p = get_proc_task(file_inode(file));
unsigned int fd;
if (!p)
return -ENOENT;
if (!dir_emit_dots(file, ctx))
goto out;
rcu_read_lock();
for (fd = ctx->pos - 2;; fd++) {
struct file *f;
struct fd_data data;
char name[10 + 1];
unsigned int len;
f = task_lookup_next_fdget_rcu(p, &fd);
ctx->pos = fd + 2LL;
if (!f)
break;
data.mode = f->f_mode;
rcu_read_unlock();
fput(f);
data.fd = fd;
len = snprintf(name, sizeof(name), "%u", fd);
if (!proc_fill_cache(file, ctx,
name, len, instantiate, p,
&data))
goto out;
cond_resched();
rcu_read_lock();
}
rcu_read_unlock();
out:
put_task_struct(p);
return 0;
}
static int proc_readfd_count(struct inode *inode, loff_t *count)
{
struct task_struct *p = get_proc_task(inode);
struct fdtable *fdt;
if (!p)
return -ENOENT;
task_lock(p);
if (p->files) {
rcu_read_lock();
fdt = files_fdtable(p->files);
*count = bitmap_weight(fdt->open_fds, fdt->max_fds);
rcu_read_unlock();
}
task_unlock(p);
put_task_struct(p);
return 0;
}
static int proc_fd_iterate(struct file *file, struct dir_context *ctx)
{
return proc_readfd_common(file, ctx, proc_fd_instantiate);
}
const struct file_operations proc_fd_operations = {
.read = generic_read_dir,
.iterate_shared = proc_fd_iterate,
.llseek = generic_file_llseek,
};
static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
}
/*
* /proc/pid/fd needs a special permission handler so that a process can still
* access /proc/self/fd after it has executed a setuid().
*/
int proc_fd_permission(struct mnt_idmap *idmap,
struct inode *inode, int mask)
{
struct task_struct *p;
int rv;
rv = generic_permission(&nop_mnt_idmap, inode, mask);
if (rv == 0)
return rv;
rcu_read_lock();
p = pid_task(proc_pid(inode), PIDTYPE_PID);
if (p && same_thread_group(p, current))
rv = 0;
rcu_read_unlock();
return rv;
}
static int proc_fd_getattr(struct mnt_idmap *idmap,
const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
struct inode *inode = d_inode(path->dentry);
int rv = 0;
generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
/* If it's a directory, put the number of open fds there */
if (S_ISDIR(inode->i_mode)) {
rv = proc_readfd_count(inode, &stat->size);
if (rv < 0)
return rv;
}
return rv;
}
const struct inode_operations proc_fd_inode_operations = {
.lookup = proc_lookupfd,
.permission = proc_fd_permission,
.getattr = proc_fd_getattr,
.setattr = proc_setattr,
};
static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
struct task_struct *task, const void *ptr)
{
const struct fd_data *data = ptr;
struct proc_inode *ei;
struct inode *inode;
inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO);
if (!inode)
return ERR_PTR(-ENOENT);
ei = PROC_I(inode);
ei->fd = data->fd;
inode->i_op = &proc_fdinfo_file_inode_operations;
inode->i_fop = &proc_fdinfo_file_operations;
tid_fd_update_inode(task, inode, 0);
return proc_splice_unmountable(inode, dentry,
&tid_fd_dentry_operations);
}
static struct dentry *
proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
}
static int proc_fdinfo_iterate(struct file *file, struct dir_context *ctx)
{
return proc_readfd_common(file, ctx,
proc_fdinfo_instantiate);
}
const struct inode_operations proc_fdinfo_inode_operations = {
.lookup = proc_lookupfdinfo,
.permission = proc_fdinfo_permission,
.setattr = proc_setattr,
};
const struct file_operations proc_fdinfo_operations = {
.read = generic_read_dir,
.iterate_shared = proc_fdinfo_iterate,
.llseek = generic_file_llseek,
};
Codebase Browser
linux