mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
![Vasiliy Kulikov](/assets/img/avatar_default.png)
Add support for mount options to restrict access to /proc/PID/ directories. The default backward-compatible "relaxed" behaviour is left untouched. The first mount option is called "hidepid" and its value defines how much info about processes we want to be available for non-owners: hidepid=0 (default) means the old behavior - anybody may read all world-readable /proc/PID/* files. hidepid=1 means users may not access any /proc/<pid>/ directories, but their own. Sensitive files like cmdline, sched*, status are now protected against other users. As permission checking done in proc_pid_permission() and files' permissions are left untouched, programs expecting specific files' modes are not confused. hidepid=2 means hidepid=1 plus all /proc/PID/ will be invisible to other users. It doesn't mean that it hides whether a process exists (it can be learned by other means, e.g. by kill -0 $PID), but it hides process' euid and egid. It compicates intruder's task of gathering info about running processes, whether some daemon runs with elevated privileges, whether another user runs some sensitive program, whether other users run any program at all, etc. gid=XXX defines a group that will be able to gather all processes' info (as in hidepid=0 mode). This group should be used instead of putting nonroot user in sudoers file or something. However, untrusted users (like daemons, etc.) which are not supposed to monitor the tasks in the whole system should not be added to the group. hidepid=1 or higher is designed to restrict access to procfs files, which might reveal some sensitive private information like precise keystrokes timings: http://www.openwall.com/lists/oss-security/2011/11/05/3 hidepid=1/2 doesn't break monitoring userspace tools. ps, top, pgrep, and conky gracefully handle EPERM/ENOENT and behave as if the current user is the only user running processes. pstree shows the process subtree which contains "pstree" process. Note: the patch doesn't deal with setuid/setgid issues of keeping preopened descriptors of procfs files (like https://lkml.org/lkml/2011/2/7/368). We rely on that the leaked information like the scheduling counters of setuid apps doesn't threaten anybody's privacy - only the user started the setuid program may read the counters. Signed-off-by: Vasiliy Kulikov <segoon@openwall.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Greg KH <greg@kroah.com> Cc: Theodore Tso <tytso@MIT.EDU> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: James Morris <jmorris@namei.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
277 lines
5.6 KiB
C
277 lines
5.6 KiB
C
/*
|
|
* linux/fs/proc/root.c
|
|
*
|
|
* Copyright (C) 1991, 1992 Linus Torvalds
|
|
*
|
|
* proc root directory handling functions
|
|
*/
|
|
|
|
#include <asm/uaccess.h>
|
|
|
|
#include <linux/errno.h>
|
|
#include <linux/time.h>
|
|
#include <linux/proc_fs.h>
|
|
#include <linux/stat.h>
|
|
#include <linux/init.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/module.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/pid_namespace.h>
|
|
#include <linux/parser.h>
|
|
|
|
#include "internal.h"
|
|
|
|
static int proc_test_super(struct super_block *sb, void *data)
|
|
{
|
|
return sb->s_fs_info == data;
|
|
}
|
|
|
|
static int proc_set_super(struct super_block *sb, void *data)
|
|
{
|
|
int err = set_anon_super(sb, NULL);
|
|
if (!err) {
|
|
struct pid_namespace *ns = (struct pid_namespace *)data;
|
|
sb->s_fs_info = get_pid_ns(ns);
|
|
}
|
|
return err;
|
|
}
|
|
|
|
enum {
|
|
Opt_gid, Opt_hidepid, Opt_err,
|
|
};
|
|
|
|
static const match_table_t tokens = {
|
|
{Opt_hidepid, "hidepid=%u"},
|
|
{Opt_gid, "gid=%u"},
|
|
{Opt_err, NULL},
|
|
};
|
|
|
|
static int proc_parse_options(char *options, struct pid_namespace *pid)
|
|
{
|
|
char *p;
|
|
substring_t args[MAX_OPT_ARGS];
|
|
int option;
|
|
|
|
if (!options)
|
|
return 1;
|
|
|
|
while ((p = strsep(&options, ",")) != NULL) {
|
|
int token;
|
|
if (!*p)
|
|
continue;
|
|
|
|
args[0].to = args[0].from = 0;
|
|
token = match_token(p, tokens, args);
|
|
switch (token) {
|
|
case Opt_gid:
|
|
if (match_int(&args[0], &option))
|
|
return 0;
|
|
pid->pid_gid = option;
|
|
break;
|
|
case Opt_hidepid:
|
|
if (match_int(&args[0], &option))
|
|
return 0;
|
|
if (option < 0 || option > 2) {
|
|
pr_err("proc: hidepid value must be between 0 and 2.\n");
|
|
return 0;
|
|
}
|
|
pid->hide_pid = option;
|
|
break;
|
|
default:
|
|
pr_err("proc: unrecognized mount option \"%s\" "
|
|
"or missing value\n", p);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
int proc_remount(struct super_block *sb, int *flags, char *data)
|
|
{
|
|
struct pid_namespace *pid = sb->s_fs_info;
|
|
return !proc_parse_options(data, pid);
|
|
}
|
|
|
|
static struct dentry *proc_mount(struct file_system_type *fs_type,
|
|
int flags, const char *dev_name, void *data)
|
|
{
|
|
int err;
|
|
struct super_block *sb;
|
|
struct pid_namespace *ns;
|
|
struct proc_inode *ei;
|
|
char *options;
|
|
|
|
if (flags & MS_KERNMOUNT) {
|
|
ns = (struct pid_namespace *)data;
|
|
options = NULL;
|
|
} else {
|
|
ns = current->nsproxy->pid_ns;
|
|
options = data;
|
|
}
|
|
|
|
sb = sget(fs_type, proc_test_super, proc_set_super, ns);
|
|
if (IS_ERR(sb))
|
|
return ERR_CAST(sb);
|
|
|
|
if (!sb->s_root) {
|
|
sb->s_flags = flags;
|
|
if (!proc_parse_options(options, ns)) {
|
|
deactivate_locked_super(sb);
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
err = proc_fill_super(sb);
|
|
if (err) {
|
|
deactivate_locked_super(sb);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
sb->s_flags |= MS_ACTIVE;
|
|
}
|
|
|
|
ei = PROC_I(sb->s_root->d_inode);
|
|
if (!ei->pid) {
|
|
rcu_read_lock();
|
|
ei->pid = get_pid(find_pid_ns(1, ns));
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
return dget(sb->s_root);
|
|
}
|
|
|
|
static void proc_kill_sb(struct super_block *sb)
|
|
{
|
|
struct pid_namespace *ns;
|
|
|
|
ns = (struct pid_namespace *)sb->s_fs_info;
|
|
kill_anon_super(sb);
|
|
put_pid_ns(ns);
|
|
}
|
|
|
|
static struct file_system_type proc_fs_type = {
|
|
.name = "proc",
|
|
.mount = proc_mount,
|
|
.kill_sb = proc_kill_sb,
|
|
};
|
|
|
|
void __init proc_root_init(void)
|
|
{
|
|
int err;
|
|
|
|
proc_init_inodecache();
|
|
err = register_filesystem(&proc_fs_type);
|
|
if (err)
|
|
return;
|
|
err = pid_ns_prepare_proc(&init_pid_ns);
|
|
if (err) {
|
|
unregister_filesystem(&proc_fs_type);
|
|
return;
|
|
}
|
|
|
|
proc_symlink("mounts", NULL, "self/mounts");
|
|
|
|
proc_net_init();
|
|
|
|
#ifdef CONFIG_SYSVIPC
|
|
proc_mkdir("sysvipc", NULL);
|
|
#endif
|
|
proc_mkdir("fs", NULL);
|
|
proc_mkdir("driver", NULL);
|
|
proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
|
|
#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
|
|
/* just give it a mountpoint */
|
|
proc_mkdir("openprom", NULL);
|
|
#endif
|
|
proc_tty_init();
|
|
#ifdef CONFIG_PROC_DEVICETREE
|
|
proc_device_tree_init();
|
|
#endif
|
|
proc_mkdir("bus", NULL);
|
|
proc_sys_init();
|
|
}
|
|
|
|
static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat
|
|
)
|
|
{
|
|
generic_fillattr(dentry->d_inode, stat);
|
|
stat->nlink = proc_root.nlink + nr_processes();
|
|
return 0;
|
|
}
|
|
|
|
static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
|
|
{
|
|
if (!proc_lookup(dir, dentry, nd)) {
|
|
return NULL;
|
|
}
|
|
|
|
return proc_pid_lookup(dir, dentry, nd);
|
|
}
|
|
|
|
static int proc_root_readdir(struct file * filp,
|
|
void * dirent, filldir_t filldir)
|
|
{
|
|
unsigned int nr = filp->f_pos;
|
|
int ret;
|
|
|
|
if (nr < FIRST_PROCESS_ENTRY) {
|
|
int error = proc_readdir(filp, dirent, filldir);
|
|
if (error <= 0)
|
|
return error;
|
|
filp->f_pos = FIRST_PROCESS_ENTRY;
|
|
}
|
|
|
|
ret = proc_pid_readdir(filp, dirent, filldir);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* The root /proc directory is special, as it has the
|
|
* <pid> directories. Thus we don't use the generic
|
|
* directory handling functions for that..
|
|
*/
|
|
static const struct file_operations proc_root_operations = {
|
|
.read = generic_read_dir,
|
|
.readdir = proc_root_readdir,
|
|
.llseek = default_llseek,
|
|
};
|
|
|
|
/*
|
|
* proc root can do almost nothing..
|
|
*/
|
|
static const struct inode_operations proc_root_inode_operations = {
|
|
.lookup = proc_root_lookup,
|
|
.getattr = proc_root_getattr,
|
|
};
|
|
|
|
/*
|
|
* This is the root "inode" in the /proc tree..
|
|
*/
|
|
struct proc_dir_entry proc_root = {
|
|
.low_ino = PROC_ROOT_INO,
|
|
.namelen = 5,
|
|
.mode = S_IFDIR | S_IRUGO | S_IXUGO,
|
|
.nlink = 2,
|
|
.count = ATOMIC_INIT(1),
|
|
.proc_iops = &proc_root_inode_operations,
|
|
.proc_fops = &proc_root_operations,
|
|
.parent = &proc_root,
|
|
.name = "/proc",
|
|
};
|
|
|
|
int pid_ns_prepare_proc(struct pid_namespace *ns)
|
|
{
|
|
struct vfsmount *mnt;
|
|
|
|
mnt = kern_mount_data(&proc_fs_type, ns);
|
|
if (IS_ERR(mnt))
|
|
return PTR_ERR(mnt);
|
|
|
|
ns->proc_mnt = mnt;
|
|
return 0;
|
|
}
|
|
|
|
void pid_ns_release_proc(struct pid_namespace *ns)
|
|
{
|
|
kern_unmount(ns->proc_mnt);
|
|
}
|