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/proc/pid/* information leak (rhbz 782686)

This commit is contained in:
Josh Boyer 2012-01-18 13:22:40 -05:00
parent e9822a3383
commit 872d2983fc
4 changed files with 570 additions and 0 deletions
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11
kernel.spec
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@ -869,6 +869,11 @@ Patch21077: 01-block-add-and-use-scsi_blk_cmd_ioctl.patch
Patch21078: 02-block-fail-SCSI-passthrough-ioctls-on-partition-devs.patch
Patch21079: 03-dm-dont-fwd-ioctls-from-LVs-to-underlying-dev.patch
#rhbz 782686
Patch21082: procfs-parse-mount-options.patch
Patch21083: procfs-add-hidepid-and-gid-mount-options.patch
Patch21084: proc-fix-null-pointer-deref-in-proc_pid_permission.patch
#rhbz 782681
Patch21085: proc-clean-up-and-fix-proc-pid-mem-handling.patch
@ -1608,6 +1613,11 @@ ApplyPatch 01-block-add-and-use-scsi_blk_cmd_ioctl.patch
ApplyPatch 02-block-fail-SCSI-passthrough-ioctls-on-partition-devs.patch
ApplyPatch 03-dm-dont-fwd-ioctls-from-LVs-to-underlying-dev.patch
#rhbz 782686
ApplyPatch procfs-parse-mount-options.patch
ApplyPatch procfs-add-hidepid-and-gid-mount-options.patch
ApplyPatch proc-fix-null-pointer-deref-in-proc_pid_permission.patch
#rhbz 782681
ApplyPatch proc-clean-up-and-fix-proc-pid-mem-handling.patch
@ -2390,6 +2400,7 @@ fi
%changelog
* Wed Jan 18 2012 Josh Boyer <jwboyer@redhat.com> 3.1.10-1
- Linux 3.1.10
- /proc/pid/* information leak (rhbz 782686)
- CVE-2012-0056 proc: clean up and fix /proc/<pid>/mem (rhbz 782681)
- loop: prevent information leak after failed read (rhbz 782687)

44
proc-fix-null-pointer-deref-in-proc_pid_permission.patch Normal file
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@ -0,0 +1,44 @@
From a2ef990ab5a6705a356d146dd773a3b359787497 Mon Sep 17 00:00:00 2001
From: Xiaotian Feng <xtfeng@gmail.com>
Date: Thu, 12 Jan 2012 17:17:08 -0800
Subject: [PATCH] proc: fix null pointer deref in proc_pid_permission()
get_proc_task() can fail to search the task and return NULL,
put_task_struct() will then bomb the kernel with following oops:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
IP: [<ffffffff81217d34>] proc_pid_permission+0x64/0xe0
PGD 112075067 PUD 112814067 PMD 0
Oops: 0002 [#1] PREEMPT SMP
This is a regression introduced by commit 0499680a ("procfs: add hidepid=
and gid= mount options"). The kernel should return -ESRCH if
get_proc_task() failed.
Signed-off-by: Xiaotian Feng <dannyfeng@tencent.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: Stephen Wilson <wilsons@start.ca>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/proc/base.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8173dfd..5485a53 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -654,6 +654,8 @@ static int proc_pid_permission(struct inode *inode, int mask)
bool has_perms;
task = get_proc_task(inode);
+ if (!task)
+ return -ESRCH;
has_perms = has_pid_permissions(pid, task, 1);
put_task_struct(task);
--
1.7.7.5

342
procfs-add-hidepid-and-gid-mount-options.patch Normal file
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@ -0,0 +1,342 @@
From 0499680a42141d86417a8fbaa8c8db806bea1201 Mon Sep 17 00:00:00 2001
From: Vasiliy Kulikov <segooon@gmail.com>
Date: Tue, 10 Jan 2012 15:11:31 -0800
Subject: [PATCH] procfs: add hidepid= and gid= mount options
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>
---
Documentation/filesystems/proc.txt | 39 ++++++++++++++++++++
fs/proc/base.c | 69 +++++++++++++++++++++++++++++++++++-
fs/proc/inode.c | 8 ++++
fs/proc/root.c | 21 +++++++++--
include/linux/pid_namespace.h | 2 +
5 files changed, 135 insertions(+), 4 deletions(-)
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 0ec91f0..12fee13 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -41,6 +41,8 @@ Table of Contents
3.5 /proc/<pid>/mountinfo - Information about mounts
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
+ 4 Configuring procfs
+ 4.1 Mount options
------------------------------------------------------------------------------
Preface
@@ -1542,3 +1544,40 @@ a task to set its own or one of its thread siblings comm value. The comm value
is limited in size compared to the cmdline value, so writing anything longer
then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
comm value.
+
+
+------------------------------------------------------------------------------
+Configuring procfs
+------------------------------------------------------------------------------
+
+4.1 Mount options
+---------------------
+
+The following mount options are supported:
+
+ hidepid= Set /proc/<pid>/ access mode.
+ gid= Set the group authorized to learn processes information.
+
+hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
+(default).
+
+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. This makes it impossible to learn whether any user runs
+specific program (given the program doesn't reveal itself by its behaviour).
+As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users,
+poorly written programs passing sensitive information via program arguments are
+now protected against local eavesdroppers.
+
+hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other
+users. It doesn't mean that it hides a fact whether a process with a specific
+pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"),
+but it hides process' uid and gid, which may be learned by stat()'ing
+/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering
+information about running processes, whether some daemon runs with elevated
+privileges, whether other user runs some sensitive program, whether other users
+run any program at all, etc.
+
+gid= defines a group authorized to learn processes information otherwise
+prohibited by hidepid=. If you use some daemon like identd which needs to learn
+information about processes information, just add identd to this group.
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 4d755fe..8173dfd 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -631,6 +631,50 @@ int proc_setattr(struct dentry *dentry, struct iattr *attr)
return 0;
}
+/*
+ * May current process learn task's sched/cmdline info (for hide_pid_min=1)
+ * or euid/egid (for hide_pid_min=2)?
+ */
+static bool has_pid_permissions(struct pid_namespace *pid,
+ struct task_struct *task,
+ int hide_pid_min)
+{
+ if (pid->hide_pid < hide_pid_min)
+ return true;
+ if (in_group_p(pid->pid_gid))
+ return true;
+ return ptrace_may_access(task, PTRACE_MODE_READ);
+}
+
+
+static int proc_pid_permission(struct inode *inode, int mask)
+{
+ struct pid_namespace *pid = inode->i_sb->s_fs_info;
+ struct task_struct *task;
+ bool has_perms;
+
+ task = get_proc_task(inode);
+ has_perms = has_pid_permissions(pid, task, 1);
+ put_task_struct(task);
+
+ if (!has_perms) {
+ if (pid->hide_pid == 2) {
+ /*
+ * Let's make getdents(), stat(), and open()
+ * consistent with each other. If a process
+ * may not stat() a file, it shouldn't be seen
+ * in procfs at all.
+ */
+ return -ENOENT;
+ }
+
+ return -EPERM;
+ }
+ return generic_permission(inode, mask);
+}
+
+
+
static const struct inode_operations proc_def_inode_operations = {
.setattr = proc_setattr,
};
@@ -1615,6 +1659,7 @@ int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
struct inode *inode = dentry->d_inode;
struct task_struct *task;
const struct cred *cred;
+ struct pid_namespace *pid = dentry->d_sb->s_fs_info;
generic_fillattr(inode, stat);
@@ -1623,6 +1668,14 @@ int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
stat->gid = 0;
task = pid_task(proc_pid(inode), PIDTYPE_PID);
if (task) {
+ if (!has_pid_permissions(pid, task, 2)) {
+ rcu_read_unlock();
+ /*
+ * This doesn't prevent learning whether PID exists,
+ * it only makes getattr() consistent with readdir().
+ */
+ return -ENOENT;
+ }
if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
task_dumpable(task)) {
cred = __task_cred(task);
@@ -3119,6 +3172,7 @@ static const struct inode_operations proc_tgid_base_inode_operations = {
.lookup = proc_tgid_base_lookup,
.getattr = pid_getattr,
.setattr = proc_setattr,
+ .permission = proc_pid_permission,
};
static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
@@ -3322,6 +3376,12 @@ static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldi
proc_pid_instantiate, iter.task, NULL);
}
+static int fake_filldir(void *buf, const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned d_type)
+{
+ return 0;
+}
+
/* for the /proc/ directory itself, after non-process stuff has been done */
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
@@ -3329,6 +3389,7 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
struct task_struct *reaper;
struct tgid_iter iter;
struct pid_namespace *ns;
+ filldir_t __filldir;
if (filp->f_pos >= PID_MAX_LIMIT + TGID_OFFSET)
goto out_no_task;
@@ -3350,8 +3411,13 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
for (iter = next_tgid(ns, iter);
iter.task;
iter.tgid += 1, iter = next_tgid(ns, iter)) {
+ if (has_pid_permissions(ns, iter.task, 2))
+ __filldir = filldir;
+ else
+ __filldir = fake_filldir;
+
filp->f_pos = iter.tgid + TGID_OFFSET;
- if (proc_pid_fill_cache(filp, dirent, filldir, iter) < 0) {
+ if (proc_pid_fill_cache(filp, dirent, __filldir, iter) < 0) {
put_task_struct(iter.task);
goto out;
}
@@ -3686,6 +3752,7 @@ static const struct inode_operations proc_task_inode_operations = {
.lookup = proc_task_lookup,
.getattr = proc_task_getattr,
.setattr = proc_setattr,
+ .permission = proc_pid_permission,
};
static const struct file_operations proc_task_operations = {
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 27c762f..84fd323 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -106,6 +106,14 @@ void __init proc_init_inodecache(void)
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 (pid->pid_gid)
+ seq_printf(seq, ",gid=%lu", (unsigned long)pid->pid_gid);
+ if (pid->hide_pid != 0)
+ seq_printf(seq, ",hidepid=%u", pid->hide_pid);
+
return 0;
}
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 6a8ac1d..46a15d8 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -38,10 +38,12 @@ static int proc_set_super(struct super_block *sb, void *data)
}
enum {
- Opt_err,
+ Opt_gid, Opt_hidepid, Opt_err,
};
static const match_table_t tokens = {
+ {Opt_hidepid, "hidepid=%u"},
+ {Opt_gid, "gid=%u"},
{Opt_err, NULL},
};
@@ -49,8 +51,7 @@ static int proc_parse_options(char *options, struct pid_namespace *pid)
{
char *p;
substring_t args[MAX_OPT_ARGS];
-
- pr_debug("proc: options = %s\n", options);
+ int option;
if (!options)
return 1;
@@ -63,6 +64,20 @@ static int proc_parse_options(char *options, struct pid_namespace *pid)
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);
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 38d1032..e7cf666 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -30,6 +30,8 @@ struct pid_namespace {
#ifdef CONFIG_BSD_PROCESS_ACCT
struct bsd_acct_struct *bacct;
#endif
+ gid_t pid_gid;
+ int hide_pid;
};
extern struct pid_namespace init_pid_ns;
--
1.7.7.5

173
procfs-parse-mount-options.patch Normal file
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@ -0,0 +1,173 @@
From 97412950b10e64f347aec4a9b759395c2465adf6 Mon Sep 17 00:00:00 2001
From: Vasiliy Kulikov <segooon@gmail.com>
Date: Tue, 10 Jan 2012 15:11:27 -0800
Subject: [PATCH] procfs: parse mount options
Add support for procfs mount options. Actual mount options are coming in
the next patches.
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/proc/inode.c | 10 +++++++++
fs/proc/internal.h | 1 +
fs/proc/root.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 64 insertions(+), 2 deletions(-)
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 51a1766..27c762f 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -7,6 +7,7 @@
#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>
@@ -17,7 +18,9 @@
#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 <asm/system.h>
#include <asm/uaccess.h>
@@ -101,12 +104,19 @@ void __init proc_init_inodecache(void)
init_once);
}
+static int proc_show_options(struct seq_file *seq, struct dentry *root)
+{
+ 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,
};
static void __pde_users_dec(struct proc_dir_entry *pde)
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 7838e5c..2925775 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -117,6 +117,7 @@ void pde_put(struct proc_dir_entry *pde);
int proc_fill_super(struct super_block *);
struct inode *proc_get_inode(struct super_block *, struct proc_dir_entry *);
+int proc_remount(struct super_block *sb, int *flags, char *data);
/*
* These are generic /proc routines that use the internal
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 03102d9..6a8ac1d 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -18,6 +18,7 @@
#include <linux/bitops.h>
#include <linux/mount.h>
#include <linux/pid_namespace.h>
+#include <linux/parser.h>
#include "internal.h"
@@ -36,6 +37,48 @@ static int proc_set_super(struct super_block *sb, void *data)
return err;
}
+enum {
+ Opt_err,
+};
+
+static const match_table_t tokens = {
+ {Opt_err, NULL},
+};
+
+static int proc_parse_options(char *options, struct pid_namespace *pid)
+{
+ char *p;
+ substring_t args[MAX_OPT_ARGS];
+
+ pr_debug("proc: options = %s\n", options);
+
+ 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) {
+ 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)
{
@@ -43,11 +86,15 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
struct super_block *sb;
struct pid_namespace *ns;
struct proc_inode *ei;
+ char *options;
- if (flags & MS_KERNMOUNT)
+ if (flags & MS_KERNMOUNT) {
ns = (struct pid_namespace *)data;
- else
+ 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))
@@ -55,6 +102,10 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
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);
--
1.7.7.5