lwn.git/fs/omfs/inode.c, branch v3.14.43

fs: Limit sys_mount to only request filesystem modules.

2013-03-04T03:36:31+00:00

Modify the request_module to prefix the file system type with "fs-" and add aliases to all of the filesystems that can be built as modules to match. A common practice is to build all of the kernel code and leave code that is not commonly needed as modules, with the result that many users are exposed to any bug anywhere in the kernel. Looking for filesystems with a fs- prefix limits the pool of possible modules that can be loaded by mount to just filesystems trivially making things safer with no real cost. Using aliases means user space can control the policy of which filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf with blacklist and alias directives. Allowing simple, safe, well understood work-arounds to known problematic software. This also addresses a rare but unfortunate problem where the filesystem name is not the same as it's module name and module auto-loading would not work. While writing this patch I saw a handful of such cases. The most significant being autofs that lives in the module autofs4. This is relevant to user namespaces because we can reach the request module in get_fs_type() without having any special permissions, and people get uncomfortable when a user specified string (in this case the filesystem type) goes all of the way to request_module. After having looked at this issue I don't think there is any particular reason to perform any filtering or permission checks beyond making it clear in the module request that we want a filesystem module. The common pattern in the kernel is to call request_module() without regards to the users permissions. In general all a filesystem module does once loaded is call register_filesystem() and go to sleep. Which means there is not much attack surface exposed by loading a filesytem module unless the filesystem is mounted. In a user namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT, which most filesystems do not set today. Acked-by: Serge Hallyn Acked-by: Kees Cook Reported-by: Kees Cook Signed-off-by: "Eric W. Biederman"

userns: Convert omfs to use kuid and kgid where appropriate

2012-09-21T10:13:16+00:00

Acked-by: Bob Copeland Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman

vfs: Rename end_writeback() to clear_inode()

2012-05-06T05:43:41+00:00

After we moved inode_sync_wait() from end_writeback() it doesn't make sense to call the function end_writeback() anymore. Rename it to clear_inode() which well says what the function really does - set I_CLEAR flag. Signed-off-by: Jan Kara Signed-off-by: Fengguang Wu

switch open-coded instances of d_make_root() to new helper

2012-03-21T01:29:35+00:00

Signed-off-by: Al Viro

omfs: propagate umode_t

2012-01-04T03:55:01+00:00

Signed-off-by: Al Viro

new helper: mount_bdev()

2010-10-29T08:16:13+00:00

... and switch of the obvious get_sb_bdev() users to ->mount() Signed-off-by: Al Viro

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/bcopeland/omfs

2010-08-10T18:47:36+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/bcopeland/omfs: omfs: fix uninitialized variable warning omfs: sanity check cluster size omfs: refuse to mount if bitmap pointer is obviously wrong omfs: check bounds on block numbers before passing to sb_bread omfs: fix memory leak

switch omfs to ->evict_inode()

2010-08-09T20:48:05+00:00

Signed-off-by: Al Viro

omfs: sanity check cluster size

2010-07-10T18:38:11+00:00

A corrupt filesystem could have a bad cluster size; this could result in the filesystem allocating too much space for files if too large, or getting stuck in omfs_allocate_block if too small. The proper range is 1-8 blocks. Reported-by: Eric Sesterhenn Signed-off-by: Bob Copeland

omfs: refuse to mount if bitmap pointer is obviously wrong

2010-07-10T18:37:39+00:00

If the free space bitmap pointer is corrupted such that it lies outside of the number of blocks in the filesystem, print a message and fail the mount so the user can fix it offline. Signed-off-by: Bob Copeland