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mnt: Fix flag handling on remount (CVE-2014-5206) 

- mnt: Only change user settable mount flags in remount
- mnt: Move the test for MNT_LOCK_READONLY from change_mount_flags into
  do_remount
- mnt: Correct permission checks in do_remount
- mnt: Change the default remount atime from relatime to the existing value
- mnt: Add tests for unprivileged remount cases that have found to be faulty

svn path=/dists/trunk/linux/; revision=21777
This commit is contained in:
Ben Hutchings 2014-09-07 22:57:20 +00:00
parent f2b6484a69
commit 7dd2587507
7 changed files with 606 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
debian/changelog vendored
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@ -3,6 +3,8 @@ linux (3.16.2-1) UNRELEASED; urgency=medium
* New upstream stable update (closes: #748615):
https://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.16.1
https://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.16.2
- kvm: iommu: fix the third parameter of kvm_iommu_put_pages
(CVE-2014-3601)
[ Ben Hutchings ]
* HID: Enable HID_RMI as module (Closes: #754519)
@ -31,6 +33,14 @@ linux (3.16.2-1) UNRELEASED; urgency=medium
* sound: Disable SND_CS5535AUDIO on all but i386 and mips*/loongson-2f
* [mips*/loongson-2f] video: Re-add and enable sm7xxfb driver, removed
upstream in 3.15
* mnt: Fix flag handling on remount (CVE-2014-5206)
- mnt: Only change user settable mount flags in remount
- mnt: Move the test for MNT_LOCK_READONLY from change_mount_flags into
do_remount
- mnt: Correct permission checks in do_remount
- mnt: Change the default remount atime from relatime to the existing value
- mnt: Add tests for unprivileged remount cases that have found to be
faulty
[ Vagrant Cascadian ]
* [armmp] Enable IMX_IPUV3_CORE (closes: #756810).

315
debian/patches/bugfix/all/mnt-Add-tests-for-unprivileged-remount-cases-that-ha.patch vendored Normal file
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@ -0,0 +1,315 @@
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Tue, 29 Jul 2014 15:50:44 -0700
Subject: [5/5] mnt: Add tests for unprivileged remount cases that have found
to be faulty
Origin: https://git.kernel.org/linus/db181ce011e3c033328608299cd6fac06ea50130
Kenton Varda <kenton@sandstorm.io> discovered that by remounting a
read-only bind mount read-only in a user namespace the
MNT_LOCK_READONLY bit would be cleared, allowing an unprivileged user
to the remount a read-only mount read-write.
Upon review of the code in remount it was discovered that the code allowed
nosuid, noexec, and nodev to be cleared. It was also discovered that
the code was allowing the per mount atime flags to be changed.
The first naive patch to fix these issues contained the flaw that using
default atime settings when remounting a filesystem could be disallowed.
To avoid this problems in the future add tests to ensure unprivileged
remounts are succeeding and failing at the appropriate times.
Cc: stable@vger.kernel.org
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/mount/Makefile | 17 ++
.../selftests/mount/unprivileged-remount-test.c | 242 +++++++++++++++++++++
3 files changed, 260 insertions(+)
create mode 100644 tools/testing/selftests/mount/Makefile
create mode 100644 tools/testing/selftests/mount/unprivileged-remount-test.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index e66e710..0a8a9db 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -4,6 +4,7 @@ TARGETS += efivarfs
TARGETS += kcmp
TARGETS += memory-hotplug
TARGETS += mqueue
+TARGETS += mount
TARGETS += net
TARGETS += ptrace
TARGETS += timers
diff --git a/tools/testing/selftests/mount/Makefile b/tools/testing/selftests/mount/Makefile
new file mode 100644
index 0000000..337d853
--- /dev/null
+++ b/tools/testing/selftests/mount/Makefile
@@ -0,0 +1,17 @@
+# Makefile for mount selftests.
+
+all: unprivileged-remount-test
+
+unprivileged-remount-test: unprivileged-remount-test.c
+ gcc -Wall -O2 unprivileged-remount-test.c -o unprivileged-remount-test
+
+# Allow specific tests to be selected.
+test_unprivileged_remount: unprivileged-remount-test
+ @if [ -f /proc/self/uid_map ] ; then ./unprivileged-remount-test ; fi
+
+run_tests: all test_unprivileged_remount
+
+clean:
+ rm -f unprivileged-remount-test
+
+.PHONY: all test_unprivileged_remount
diff --git a/tools/testing/selftests/mount/unprivileged-remount-test.c b/tools/testing/selftests/mount/unprivileged-remount-test.c
new file mode 100644
index 0000000..1b3ff2f
--- /dev/null
+++ b/tools/testing/selftests/mount/unprivileged-remount-test.c
@@ -0,0 +1,242 @@
+#define _GNU_SOURCE
+#include <sched.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/mount.h>
+#include <sys/wait.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <stdbool.h>
+#include <stdarg.h>
+
+#ifndef CLONE_NEWNS
+# define CLONE_NEWNS 0x00020000
+#endif
+#ifndef CLONE_NEWUTS
+# define CLONE_NEWUTS 0x04000000
+#endif
+#ifndef CLONE_NEWIPC
+# define CLONE_NEWIPC 0x08000000
+#endif
+#ifndef CLONE_NEWNET
+# define CLONE_NEWNET 0x40000000
+#endif
+#ifndef CLONE_NEWUSER
+# define CLONE_NEWUSER 0x10000000
+#endif
+#ifndef CLONE_NEWPID
+# define CLONE_NEWPID 0x20000000
+#endif
+
+#ifndef MS_RELATIME
+#define MS_RELATIME (1 << 21)
+#endif
+#ifndef MS_STRICTATIME
+#define MS_STRICTATIME (1 << 24)
+#endif
+
+static void die(char *fmt, ...)
+{
+ va_list ap;
+ va_start(ap, fmt);
+ vfprintf(stderr, fmt, ap);
+ va_end(ap);
+ exit(EXIT_FAILURE);
+}
+
+static void write_file(char *filename, char *fmt, ...)
+{
+ char buf[4096];
+ int fd;
+ ssize_t written;
+ int buf_len;
+ va_list ap;
+
+ va_start(ap, fmt);
+ buf_len = vsnprintf(buf, sizeof(buf), fmt, ap);
+ va_end(ap);
+ if (buf_len < 0) {
+ die("vsnprintf failed: %s\n",
+ strerror(errno));
+ }
+ if (buf_len >= sizeof(buf)) {
+ die("vsnprintf output truncated\n");
+ }
+
+ fd = open(filename, O_WRONLY);
+ if (fd < 0) {
+ die("open of %s failed: %s\n",
+ filename, strerror(errno));
+ }
+ written = write(fd, buf, buf_len);
+ if (written != buf_len) {
+ if (written >= 0) {
+ die("short write to %s\n", filename);
+ } else {
+ die("write to %s failed: %s\n",
+ filename, strerror(errno));
+ }
+ }
+ if (close(fd) != 0) {
+ die("close of %s failed: %s\n",
+ filename, strerror(errno));
+ }
+}
+
+static void create_and_enter_userns(void)
+{
+ uid_t uid;
+ gid_t gid;
+
+ uid = getuid();
+ gid = getgid();
+
+ if (unshare(CLONE_NEWUSER) !=0) {
+ die("unshare(CLONE_NEWUSER) failed: %s\n",
+ strerror(errno));
+ }
+
+ write_file("/proc/self/uid_map", "0 %d 1", uid);
+ write_file("/proc/self/gid_map", "0 %d 1", gid);
+
+ if (setgroups(0, NULL) != 0) {
+ die("setgroups failed: %s\n",
+ strerror(errno));
+ }
+ if (setgid(0) != 0) {
+ die ("setgid(0) failed %s\n",
+ strerror(errno));
+ }
+ if (setuid(0) != 0) {
+ die("setuid(0) failed %s\n",
+ strerror(errno));
+ }
+}
+
+static
+bool test_unpriv_remount(int mount_flags, int remount_flags, int invalid_flags)
+{
+ pid_t child;
+
+ child = fork();
+ if (child == -1) {
+ die("fork failed: %s\n",
+ strerror(errno));
+ }
+ if (child != 0) { /* parent */
+ pid_t pid;
+ int status;
+ pid = waitpid(child, &status, 0);
+ if (pid == -1) {
+ die("waitpid failed: %s\n",
+ strerror(errno));
+ }
+ if (pid != child) {
+ die("waited for %d got %d\n",
+ child, pid);
+ }
+ if (!WIFEXITED(status)) {
+ die("child did not terminate cleanly\n");
+ }
+ return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false;
+ }
+
+ create_and_enter_userns();
+ if (unshare(CLONE_NEWNS) != 0) {
+ die("unshare(CLONE_NEWNS) failed: %s\n",
+ strerror(errno));
+ }
+
+ if (mount("testing", "/tmp", "ramfs", mount_flags, NULL) != 0) {
+ die("mount of /tmp failed: %s\n",
+ strerror(errno));
+ }
+
+ create_and_enter_userns();
+
+ if (unshare(CLONE_NEWNS) != 0) {
+ die("unshare(CLONE_NEWNS) failed: %s\n",
+ strerror(errno));
+ }
+
+ if (mount("/tmp", "/tmp", "none",
+ MS_REMOUNT | MS_BIND | remount_flags, NULL) != 0) {
+ /* system("cat /proc/self/mounts"); */
+ die("remount of /tmp failed: %s\n",
+ strerror(errno));
+ }
+
+ if (mount("/tmp", "/tmp", "none",
+ MS_REMOUNT | MS_BIND | invalid_flags, NULL) == 0) {
+ /* system("cat /proc/self/mounts"); */
+ die("remount of /tmp with invalid flags "
+ "succeeded unexpectedly\n");
+ }
+ exit(EXIT_SUCCESS);
+}
+
+static bool test_unpriv_remount_simple(int mount_flags)
+{
+ return test_unpriv_remount(mount_flags, mount_flags, 0);
+}
+
+static bool test_unpriv_remount_atime(int mount_flags, int invalid_flags)
+{
+ return test_unpriv_remount(mount_flags, mount_flags, invalid_flags);
+}
+
+int main(int argc, char **argv)
+{
+ if (!test_unpriv_remount_simple(MS_RDONLY|MS_NODEV)) {
+ die("MS_RDONLY malfunctions\n");
+ }
+ if (!test_unpriv_remount_simple(MS_NODEV)) {
+ die("MS_NODEV malfunctions\n");
+ }
+ if (!test_unpriv_remount_simple(MS_NOSUID|MS_NODEV)) {
+ die("MS_NOSUID malfunctions\n");
+ }
+ if (!test_unpriv_remount_simple(MS_NOEXEC|MS_NODEV)) {
+ die("MS_NOEXEC malfunctions\n");
+ }
+ if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODEV,
+ MS_NOATIME|MS_NODEV))
+ {
+ die("MS_RELATIME malfunctions\n");
+ }
+ if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODEV,
+ MS_NOATIME|MS_NODEV))
+ {
+ die("MS_STRICTATIME malfunctions\n");
+ }
+ if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODEV,
+ MS_STRICTATIME|MS_NODEV))
+ {
+ die("MS_RELATIME malfunctions\n");
+ }
+ if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODIRATIME|MS_NODEV,
+ MS_NOATIME|MS_NODEV))
+ {
+ die("MS_RELATIME malfunctions\n");
+ }
+ if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODIRATIME|MS_NODEV,
+ MS_NOATIME|MS_NODEV))
+ {
+ die("MS_RELATIME malfunctions\n");
+ }
+ if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODIRATIME|MS_NODEV,
+ MS_STRICTATIME|MS_NODEV))
+ {
+ die("MS_RELATIME malfunctions\n");
+ }
+ if (!test_unpriv_remount(MS_STRICTATIME|MS_NODEV, MS_NODEV,
+ MS_NOATIME|MS_NODEV))
+ {
+ die("Default atime malfunctions\n");
+ }
+ return EXIT_SUCCESS;
+}

53
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@ -0,0 +1,53 @@
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Mon, 28 Jul 2014 17:36:04 -0700
Subject: [4/5] mnt: Change the default remount atime from relatime to the
existing value
Origin: https://git.kernel.org/linus/ffbc6f0ead47fa5a1dc9642b0331cb75c20a640e
Since March 2009 the kernel has treated the state that if no
MS_..ATIME flags are passed then the kernel defaults to relatime.
Defaulting to relatime instead of the existing atime state during a
remount is silly, and causes problems in practice for people who don't
specify any MS_...ATIME flags and to get the default filesystem atime
setting. Those users may encounter a permission error because the
default atime setting does not work.
A default that does not work and causes permission problems is
ridiculous, so preserve the existing value to have a default
atime setting that is always guaranteed to work.
Using the default atime setting in this way is particularly
interesting for applications built to run in restricted userspace
environments without /proc mounted, as the existing atime mount
options of a filesystem can not be read from /proc/mounts.
In practice this fixes user space that uses the default atime
setting on remount that are broken by the permission checks
keeping less privileged users from changing more privileged users
atime settings.
Cc: stable@vger.kernel.org
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/namespace.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2475,6 +2475,14 @@ long do_mount(const char *dev_name, cons
if (flags & MS_RDONLY)
mnt_flags |= MNT_READONLY;
+ /* The default atime for remount is preservation */
+ if ((flags & MS_REMOUNT) &&
+ ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME |
+ MS_STRICTATIME)) == 0)) {
+ mnt_flags &= ~MNT_ATIME_MASK;
+ mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK;
+ }
+
flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN |
MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT |
MS_STRICTATIME);

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@ -0,0 +1,125 @@
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Mon, 28 Jul 2014 17:26:07 -0700
Subject: [3/5] mnt: Correct permission checks in do_remount
Origin: https://git.kernel.org/linus/9566d6742852c527bf5af38af5cbb878dad75705
While invesgiating the issue where in "mount --bind -oremount,ro ..."
would result in later "mount --bind -oremount,rw" succeeding even if
the mount started off locked I realized that there are several
additional mount flags that should be locked and are not.
In particular MNT_NOSUID, MNT_NODEV, MNT_NOEXEC, and the atime
flags in addition to MNT_READONLY should all be locked. These
flags are all per superblock, can all be changed with MS_BIND,
and should not be changable if set by a more privileged user.
The following additions to the current logic are added in this patch.
- nosuid may not be clearable by a less privileged user.
- nodev may not be clearable by a less privielged user.
- noexec may not be clearable by a less privileged user.
- atime flags may not be changeable by a less privileged user.
The logic with atime is that always setting atime on access is a
global policy and backup software and auditing software could break if
atime bits are not updated (when they are configured to be updated),
and serious performance degradation could result (DOS attack) if atime
updates happen when they have been explicitly disabled. Therefore an
unprivileged user should not be able to mess with the atime bits set
by a more privileged user.
The additional restrictions are implemented with the addition of
MNT_LOCK_NOSUID, MNT_LOCK_NODEV, MNT_LOCK_NOEXEC, and MNT_LOCK_ATIME
mnt flags.
Taken together these changes and the fixes for MNT_LOCK_READONLY
should make it safe for an unprivileged user to create a user
namespace and to call "mount --bind -o remount,... ..." without
the danger of mount flags being changed maliciously.
Cc: stable@vger.kernel.org
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/namespace.c | 36 +++++++++++++++++++++++++++++++++---
include/linux/mount.h | 5 +++++
2 files changed, 38 insertions(+), 3 deletions(-)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -891,8 +891,21 @@ static struct mount *clone_mnt(struct mo
mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED);
/* Don't allow unprivileged users to change mount flags */
- if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY))
- mnt->mnt.mnt_flags |= MNT_LOCK_READONLY;
+ if (flag & CL_UNPRIVILEGED) {
+ mnt->mnt.mnt_flags |= MNT_LOCK_ATIME;
+
+ if (mnt->mnt.mnt_flags & MNT_READONLY)
+ mnt->mnt.mnt_flags |= MNT_LOCK_READONLY;
+
+ if (mnt->mnt.mnt_flags & MNT_NODEV)
+ mnt->mnt.mnt_flags |= MNT_LOCK_NODEV;
+
+ if (mnt->mnt.mnt_flags & MNT_NOSUID)
+ mnt->mnt.mnt_flags |= MNT_LOCK_NOSUID;
+
+ if (mnt->mnt.mnt_flags & MNT_NOEXEC)
+ mnt->mnt.mnt_flags |= MNT_LOCK_NOEXEC;
+ }
/* Don't allow unprivileged users to reveal what is under a mount */
if ((flag & CL_UNPRIVILEGED) && list_empty(&old->mnt_expire))
@@ -1933,6 +1946,23 @@ static int do_remount(struct path *path,
!(mnt_flags & MNT_READONLY)) {
return -EPERM;
}
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) &&
+ !(mnt_flags & MNT_NODEV)) {
+ return -EPERM;
+ }
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) &&
+ !(mnt_flags & MNT_NOSUID)) {
+ return -EPERM;
+ }
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_NOEXEC) &&
+ !(mnt_flags & MNT_NOEXEC)) {
+ return -EPERM;
+ }
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) &&
+ ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) {
+ return -EPERM;
+ }
+
err = security_sb_remount(sb, data);
if (err)
return err;
@@ -2131,7 +2161,7 @@ static int do_new_mount(struct path *pat
*/
if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) {
flags |= MS_NODEV;
- mnt_flags |= MNT_NODEV;
+ mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV;
}
}
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -45,12 +45,17 @@ struct mnt_namespace;
#define MNT_USER_SETTABLE_MASK (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
| MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
| MNT_READONLY)
+#define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED)
#define MNT_INTERNAL 0x4000
+#define MNT_LOCK_ATIME 0x040000
+#define MNT_LOCK_NOEXEC 0x080000
+#define MNT_LOCK_NOSUID 0x100000
+#define MNT_LOCK_NODEV 0x200000
#define MNT_LOCK_READONLY 0x400000
#define MNT_LOCKED 0x800000
#define MNT_DOOMED 0x1000000

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@ -0,0 +1,50 @@
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Mon, 28 Jul 2014 17:10:56 -0700
Subject: [2/5] mnt: Move the test for MNT_LOCK_READONLY from
change_mount_flags into do_remount
Origin: https://git.kernel.org/linus/07b645589dcda8b7a5249e096fece2a67556f0f4
There are no races as locked mount flags are guaranteed to never change.
Moving the test into do_remount makes it more visible, and ensures all
filesystem remounts pass the MNT_LOCK_READONLY permission check. This
second case is not an issue today as filesystem remounts are guarded
by capable(CAP_DAC_ADMIN) and thus will always fail in less privileged
mount namespaces, but it could become an issue in the future.
Cc: stable@vger.kernel.org
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/namespace.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1898,9 +1898,6 @@ static int change_mount_flags(struct vfs
if (readonly_request == __mnt_is_readonly(mnt))
return 0;
- if (mnt->mnt_flags & MNT_LOCK_READONLY)
- return -EPERM;
-
if (readonly_request)
error = mnt_make_readonly(real_mount(mnt));
else
@@ -1926,6 +1923,16 @@ static int do_remount(struct path *path,
if (path->dentry != path->mnt->mnt_root)
return -EINVAL;
+ /* Don't allow changing of locked mnt flags.
+ *
+ * No locks need to be held here while testing the various
+ * MNT_LOCK flags because those flags can never be cleared
+ * once they are set.
+ */
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) &&
+ !(mnt_flags & MNT_READONLY)) {
+ return -EPERM;
+ }
err = security_sb_remount(sb, data);
if (err)
return err;

48
debian/patches/bugfix/all/mnt-Only-change-user-settable-mount-flags-in-remount.patch vendored Normal file
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@ -0,0 +1,48 @@
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Mon, 28 Jul 2014 16:26:53 -0700
Subject: [1/5] mnt: Only change user settable mount flags in remount
Origin: https://git.kernel.org/linus/a6138db815df5ee542d848318e5dae681590fccd
Kenton Varda <kenton@sandstorm.io> discovered that by remounting a
read-only bind mount read-only in a user namespace the
MNT_LOCK_READONLY bit would be cleared, allowing an unprivileged user
to the remount a read-only mount read-write.
Correct this by replacing the mask of mount flags to preserve
with a mask of mount flags that may be changed, and preserve
all others. This ensures that any future bugs with this mask and
remount will fail in an easy to detect way where new mount flags
simply won't change.
Cc: stable@vger.kernel.org
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/namespace.c | 2 +-
include/linux/mount.h | 4 +++-
2 files changed, 4 insertions(+), 2 deletions(-)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1939,7 +1939,7 @@ static int do_remount(struct path *path,
err = do_remount_sb(sb, flags, data, 0);
if (!err) {
lock_mount_hash();
- mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK;
+ mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
mnt->mnt.mnt_flags = mnt_flags;
touch_mnt_namespace(mnt->mnt_ns);
unlock_mount_hash();
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -42,7 +42,9 @@ struct mnt_namespace;
* flag, consider how it interacts with shared mounts.
*/
#define MNT_SHARED_MASK (MNT_UNBINDABLE)
-#define MNT_PROPAGATION_MASK (MNT_SHARED | MNT_UNBINDABLE)
+#define MNT_USER_SETTABLE_MASK (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
+ | MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
+ | MNT_READONLY)
#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED)

5
debian/patches/series vendored
View File

@ -106,3 +106,8 @@ bugfix/s390/s390-3215-fix-hanging-console-issue.patch
bugfix/all/aio-fix-reqs_available-handling.patch
features/all/virtio-scsi-Implement-change_queue_depth-for-virtscs.patch
debian/revert-staging-sm7xxfb-remove-driver.patch
bugfix/all/mnt-Only-change-user-settable-mount-flags-in-remount.patch
bugfix/all/mnt-Move-the-test-for-MNT_LOCK_READONLY-from-change_.patch
bugfix/all/mnt-Correct-permission-checks-in-do_remount.patch
bugfix/all/mnt-Change-the-default-remount-atime-from-relatime-t.patch
bugfix/all/mnt-Add-tests-for-unprivileged-remount-cases-that-ha.patch