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Eric W. Biederman 7f78e03513 fs: Limit sys_mount to only request filesystem modules. ... 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 <serge.hallyn@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Reported-by: Kees Cook <keescook@google.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>		12 years ago
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Kconfig	GFS2: use depends instead of select in kconfig	13 years ago
Makefile	GFS2: Rename ops_inode.c to inode.c	14 years ago
acl.c	gfs2: Use uid_eq and gid_eq where appropriate	12 years ago
acl.h	fs: take the ACL checks to common code	14 years ago
aops.c	GFS2: Use ->writepages for ordered writes	12 years ago
bmap.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	12 years ago
bmap.h	GFS2: New truncate sequence	15 years ago
dentry.c	stop passing nameidata * to ->d_revalidate()	13 years ago
dir.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	12 years ago
dir.h	GFS2: Add readahead to sequential directory traversal	13 years ago
export.c	fs: encode_fh: return FILEID_INVALID if invalid fid_type	12 years ago
file.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	12 years ago
gfs2.h	…
glock.c	GFS2: Split glock lru processing into two parts	12 years ago
glock.h	GFS2: Review bug traps in glops.c	12 years ago
glops.c	gfs2: Convert uids and gids between dinodes and vfs inodes.	12 years ago
glops.h	GFS2: Fix AIL flush issue during fsync	14 years ago
incore.h	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	12 years ago
inode.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	12 years ago
inode.h	GFS2: Remove unused argument from gfs2_internal_read	13 years ago
lock_dlm.c	GFS2: fix skip unlock condition	12 years ago
log.c	GFS2: Use ->writepages for ordered writes	12 years ago
log.h	GFS2: Use ->writepages for ordered writes	12 years ago
lops.c	GFS2: Copy gfs2_trans_add_bh into new data/meta functions	12 years ago
lops.h	GFS2: Merge gfs2_attach_bufdata() into trans.c	12 years ago
main.c	GFS2: Fold quota data into the reservations struct	13 years ago
meta_io.c	GFS2: Merge gfs2_attach_bufdata() into trans.c	12 years ago
meta_io.h	GFS2: Merge gfs2_attach_bufdata() into trans.c	12 years ago
ops_fstype.c	fs: Limit sys_mount to only request filesystem modules.	12 years ago
quota.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	12 years ago
quota.h	gfs2: Use kuid_t and kgid_t types where appropriate.	12 years ago
recovery.c	GFS2: fail mount if journal recovery fails	13 years ago
recovery.h	gfs2: use workqueue instead of slow-work	15 years ago
rgrp.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	12 years ago
rgrp.h	GFS2: Add Orlov allocator	12 years ago
super.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	12 years ago
super.h	GFS2: Clean up freeze code	12 years ago
sys.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	12 years ago
sys.h	GFS2: dlm based recovery coordination	13 years ago
trace_gfs2.h	GFS2: don't reference inode's glock during block allocation trace	12 years ago
trans.c	GFS2: Use ->writepages for ordered writes	12 years ago
trans.h	GFS2: Split gfs2_trans_add_bh() into two	12 years ago
util.c	GFS2: Reinstate withdraw ack system	12 years ago
util.h	GFS2: Fix error handling when reading an invalid block from the journal	13 years ago
xattr.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	12 years ago
xattr.h	sanitize xattr handler prototypes	15 years ago