As a matter of policy MNT_READONLY should not be changable if the
original mounter had more privileges than creator of the mount
namespace.
Add the flag CL_UNPRIVILEGED to note when we are copying a mount from
a mount namespace that requires more privileges to a mount namespace
that requires fewer privileges.
When the CL_UNPRIVILEGED flag is set cause clone_mnt to set MNT_NO_REMOUNT
if any of the mnt flags that should never be changed are set.
This protects both mount propagation and the initial creation of a less
privileged mount namespace.
Cc: stable@vger.kernel.org
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
When a read-only bind mount is copied from mount namespace in a higher
privileged user namespace to a mount namespace in a lesser privileged
user namespace, it should not be possible to remove the the read-only
restriction.
Add a MNT_LOCK_READONLY mount flag to indicate that a mount must
remain read-only.
CC: stable@vger.kernel.org
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Guarantee that the policy of which files may be access that is
established by setting the root directory will not be violated
by user namespaces by verifying that the root directory points
to the root of the mount namespace at the time of user namespace
creation.
Changing the root is a privileged operation, and as a matter of policy
it serves to limit unprivileged processes to files below the current
root directory.
For reasons of simplicity and comprehensibility the privilege to
change the root directory is gated solely on the CAP_SYS_CHROOT
capability in the user namespace. Therefore when creating a user
namespace we must ensure that the policy of which files may be access
can not be violated by changing the root directory.
Anyone who runs a processes in a chroot and would like to use user
namespace can setup the same view of filesystems with a mount
namespace instead. With this result that this is not a practical
limitation for using user namespaces.
Cc: stable@vger.kernel.org
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Pull btrfs fixes from Chris Mason:
"Eric's rcu barrier patch fixes a long standing problem with our
unmount code hanging on to devices in workqueue helpers. Liu Bo
nailed down a difficult assertion for in-memory extent mappings."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs: fix warning of free_extent_map
Btrfs: fix warning when creating snapshots
Btrfs: return as soon as possible when edquot happens
Btrfs: return EIO if we have extent tree corruption
btrfs: use rcu_barrier() to wait for bdev puts at unmount
Btrfs: remove btrfs_try_spin_lock
Btrfs: get better concurrency for snapshot-aware defrag work
Users report that an extent map's list is still linked when it's actually
going to be freed from cache.
The story is that
a) when we're going to drop an extent map and may split this large one into
smaller ems, and if this large one is flagged as EXTENT_FLAG_LOGGING which means
that it's on the list to be logged, then the smaller ems split from it will also
be flagged as EXTENT_FLAG_LOGGING, and this is _not_ expected.
b) we'll keep ems from unlinking the list and freeing when they are flagged with
EXTENT_FLAG_LOGGING, because the log code holds one reference.
The end result is the warning, but the truth is that we set the flag
EXTENT_FLAG_LOGGING only during fsync.
So clear flag EXTENT_FLAG_LOGGING for extent maps split from a large one.
Reported-by: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de>
Reported-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Pull ext2, ext3, reiserfs, quota fixes from Jan Kara:
"A fix for regression in ext2, and a format string issue in ext3. The
rest isn't too serious."
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
ext2: Fix BUG_ON in evict() on inode deletion
reiserfs: Use kstrdup instead of kmalloc/strcpy
ext3: Fix format string issues
quota: add missing use of dq_data_lock in __dquot_initialize
Creating snapshot passes extent_root to commit its transaction,
but it can lead to the warning of checking root for quota in
the __btrfs_end_transaction() when someone else is committing
the current transaction. Since we've recorded the needed root
in trans_handle, just use it to get rid of the warning.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
The callers of lookup_inline_extent_info all handle getting an error back
properly, so return an error if we have corruption instead of being a jerk and
panicing. Still WARN_ON() since this is kind of crucial and I've been seeing it
a bit too much recently for my taste, I think we're doing something wrong
somewhere. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Doing this would reliably fail with -EBUSY for me:
# mount /dev/sdb2 /mnt/scratch; umount /mnt/scratch; mkfs.btrfs -f /dev/sdb2
...
unable to open /dev/sdb2: Device or resource busy
because mkfs.btrfs tries to open the device O_EXCL, and somebody still has it.
Using systemtap to track bdev gets & puts shows a kworker thread doing a
blkdev put after mkfs attempts a get; this is left over from the unmount
path:
btrfs_close_devices
__btrfs_close_devices
call_rcu(&device->rcu, free_device);
free_device
INIT_WORK(&device->rcu_work, __free_device);
schedule_work(&device->rcu_work);
so unmount might complete before __free_device fires & does its blkdev_put.
Adding an rcu_barrier() to btrfs_close_devices() causes unmount to wait
until all blkdev_put()s are done, and the device is truly free once
unmount completes.
Cc: stable@vger.kernel.org
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Pull namespace bugfixes from Eric Biederman:
"This tree includes a partial revert for "fs: Limit sys_mount to only
request filesystem modules." When I added the new style module aliases
to the filesystems I deleted the old ones. A bad move. It turns out
that distributions like Arch linux use module aliases when
constructing ramdisks. Which meant ultimately that an ext3 filesystem
mounted with ext4 would not result in the ext4 module being put into
the ramdisk.
The other change in this tree adds a handful of filesystem module
alias I simply failed to add the first time. Which inconvinienced a
few folks using cifs.
I don't want to inconvinience folks any longer than I have to so here
are these trivial fixes."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
fs: Readd the fs module aliases.
fs: Limit sys_mount to only request filesystem modules. (Part 3)
Commit 8e3dffc6 introduced a regression where deleting inode with
large extended attributes leads to triggering
BUG_ON(inode->i_state != (I_FREEING | I_CLEAR))
in fs/inode.c:evict(). That happens because freeing of xattr block
dirtied the inode and it happened after clear_inode() has been called.
Fix the issue by moving removal of xattr block into ext2_evict_inode()
before clear_inode() call close to a place where data blocks are
truncated. That is also more logical place and removes surprising
requirement that ext2_free_blocks() mustn't dirty the inode.
Reported-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
I had assumed that the only use of module aliases for filesystems
prior to "fs: Limit sys_mount to only request filesystem modules."
was in request_module. It turns out I was wrong. At least mkinitcpio
in Arch linux uses these aliases.
So readd the preexising aliases, to keep from breaking userspace.
Userspace eventually will have to follow and use the same aliases the
kernel does. So at some point we may be delete these aliases without
problems. However that day is not today.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Looking at mm/process_vm_access.c:process_vm_rw() and comparing it to
compat_process_vm_rw() shows that the compatibility code requires an
explicit "access_ok()" check before calling
compat_rw_copy_check_uvector(). The same difference seems to appear when
we compare fs/read_write.c:do_readv_writev() to
fs/compat.c:compat_do_readv_writev().
This subtle difference between the compat and non-compat requirements
should probably be debated, as it seems to be error-prone. In fact,
there are two others sites that use this function in the Linux kernel,
and they both seem to get it wrong:
Now shifting our attention to fs/aio.c, we see that aio_setup_iocb()
also ends up calling compat_rw_copy_check_uvector() through
aio_setup_vectored_rw(). Unfortunately, the access_ok() check appears to
be missing. Same situation for
security/keys/compat.c:compat_keyctl_instantiate_key_iov().
I propose that we add the access_ok() check directly into
compat_rw_copy_check_uvector(), so callers don't have to worry about it,
and it therefore makes the compat call code similar to its non-compat
counterpart. Place the access_ok() check in the same location where
copy_from_user() can trigger a -EFAULT error in the non-compat code, so
the ABI behaviors are alike on both compat and non-compat.
While we are here, fix compat_do_readv_writev() so it checks for
compat_rw_copy_check_uvector() negative return values.
And also, fix a memory leak in compat_keyctl_instantiate_key_iov() error
handling.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If you open a pipe for neither read nor write, the pipe code will not
add any usage counters to the pipe, causing the 'struct pipe_inode_info"
to be potentially released early.
That doesn't normally matter, since you cannot actually use the pipe,
but the pipe release code - particularly fasync handling - still expects
the actual pipe infrastructure to all be there. And rather than adding
NULL pointer checks, let's just disallow this case, the same way we
already do for the named pipe ("fifo") case.
This is ancient going back to pre-2.4 days, and until trinity, nobody
naver noticed.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ext3_msg() takes the printk prefix as the second parameter and the
format string as the third parameter. Two callers of ext3_msg omit the
prefix and pass the format string as the second parameter and the first
parameter to the format string as the third parameter. In both cases
this string comes from an arbitrary source. Which means the string may
contain format string characters, which will
lead to undefined and potentially harmful behavior.
The issue was introduced in commit 4cf46b67eb("ext3: Unify log messages
in ext3") and is fixed by this patch.
CC: stable@vger.kernel.org
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jan Kara <jack@suse.cz>
The bulk of __dquot_initialize runs under the dqptr_sem which
protects the inode->i_dquot pointers. It doesn't protect the
dereferenced contents, though. Those are protected by the
dq_data_lock, which is missing around the dquot_resv_space call.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Somehow I failed to add the MODULE_ALIAS_FS for cifs, hostfs, hpfs,
squashfs, and udf despite what I thought were my careful checks :(
Add them now.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
With the commit 3be2be0a32 we removed vmtruncate,
but actaully there is no need to call inode_newsize_ok() because the checks are
already done in inode_change_ok() at the begin of the function.
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Pull namespace bugfixes from Eric Biederman:
"This is three simple fixes against 3.9-rc1. I have tested each of
these fixes and verified they work correctly.
The userns oops in key_change_session_keyring and the BUG_ON triggered
by proc_ns_follow_link were found by Dave Jones.
I am including the enhancement for mount to only trigger requests of
filesystem modules here instead of delaying this for the 3.10 merge
window because it is both trivial and the kind of change that tends to
bit-rot if left untouched for two months."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
proc: Use nd_jump_link in proc_ns_follow_link
fs: Limit sys_mount to only request filesystem modules (Part 2).
fs: Limit sys_mount to only request filesystem modules.
userns: Stop oopsing in key_change_session_keyring
Eric W. Biederman
Linus Torvalds
Liu Bo
Wang Shilong
Josef Bacik
Eric Sandeen
Tejun Heo
Jan Kara
Mathieu Desnoyers
Al Viro
Ionut-Gabriel Radu
Lars-Peter Clausen
Jeff Mahoney
Marco Stornelli