autofs: fix careless error in recent commit commit 302ec300ef8a545a7fc7f667e5fd743b091c2eeb upstream. Commit ecc0c469f277 ("autofs: don't fail mount for transient error") was meant to replace an 'if' with a 'switch', but instead added the 'switch' leaving the case in place. Link: http://lkml.kernel.org/r/87zi6wstmw.fsf@notabene.neil.brown.name Fixes: ecc0c469f277 ("autofs: don't fail mount for transient error") Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: NeilBrown <neilb@suse.com> Cc: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: autofs4_write() doesn't take an autofs_sb_info pointer] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
autofs: don't fail mount for transient error commit ecc0c469f27765ed1e2b967be0aa17cee1a60b76 upstream. Currently if the autofs kernel module gets an error when writing to the pipe which links to the daemon, then it marks the whole moutpoint as catatonic, and it will stop working. It is possible that the error is transient. This can happen if the daemon is slow and more than 16 requests queue up. If a subsequent process tries to queue a request, and is then signalled, the write to the pipe will return -ERESTARTSYS and autofs will take that as total failure. So change the code to assess -ERESTARTSYS and -ENOMEM as transient failures which only abort the current request, not the whole mountpoint. It isn't a crash or a data corruption, but having autofs mountpoints suddenly stop working is rather inconvenient. Ian said: : And given the problems with a half dozen (or so) user space applications : consuming large amounts of CPU under heavy mount and umount activity this : could happen more easily than we expect. Link: http://lkml.kernel.org/r/87y3norvgp.fsf@notabene.neil.brown.name Signed-off-by: NeilBrown <neilb@suse.com> Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: autofs4_write() doesn't take an autofs_sb_info pointer] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
autofs4: catatonic_mode vs. notify_daemon race commit 8753333266be67ff3a984ac1f6566d31c260bee4 upstream. we need to hold ->wq_mutex while we are forming the packet to send, lest we have autofs4_catatonic_mode() setting wq->name.name to NULL just as autofs4_notify_daemon() decides to memcpy() from it... We do have check for catatonic mode immediately after that (under ->wq_mutex, as it ought to be) and packet won't be actually sent, but it'll be too late for us if we oops on that memcpy() from NULL... Fix is obvious - just extend the area covered by ->wq_mutex over that switch and check whether it's catatonic *before* doing anything else. Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
autofs4: autofs4_wait() vs. autofs4_catatonic_mode() race commit 4041bcdc7bef06a2fb29c57394c713a74bd13b08 upstream. We need to recheck ->catatonic after autofs4_wait() got ->wq_mutex for good, or we might end up with wq inserted into queue after autofs4_catatonic_mode() had done its thing. It will stick there forever, since there won't be anything to clear its ->name.name. A bit of a complication: validate_request() drops and regains ->wq_mutex. It actually ends up the most convenient place to stick the check into... Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Revert "autofs: work around unhappy compat problem on x86-64" commit fcbf94b9dedd2ce08e798a99aafc94fec8668161 upstream. This reverts commit a32744d4abae24572eff7269bc17895c41bd0085. While that commit was technically the right thing to do, and made the x86-64 compat mode work identically to native 32-bit mode (and thus fixing the problem with a 32-bit systemd install on a 64-bit kernel), it turns out that the automount binaries had workarounds for this compat problem. Now, the workarounds are disgusting: doing an "uname()" to find out the architecture of the kernel, and then comparing it for the 64-bit cases and fixing up the size of the read() in automount for those. And they were confused: it's not actually a generic 64-bit issue at all, it's very much tied to just x86-64, which has different alignment for an 'u64' in 64-bit mode than in 32-bit mode. But the end result is that fixing the compat layer actually breaks the case of a 32-bit automount on a x86-64 kernel. There are various approaches to fix this (including just doing a "strcmp()" on current->comm and comparing it to "automount"), but I think that I will do the one that teaches pipes about a special "packet mode", which will allow user space to not have to care too deeply about the padding at the end of the autofs packet. That change will make the compat workaround unnecessary, so let's revert it first, and get automount working again in compat mode. The packetized pipes will then fix autofs for systemd. Reported-and-requested-by: Michael Tokarev <mjt@tls.msk.ru> Cc: Ian Kent <raven@themaw.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
autofs: work around unhappy compat problem on x86-64 commit a32744d4abae24572eff7269bc17895c41bd0085 upstream. When the autofs protocol version 5 packet type was added in commit 5c0a32fc2cd0 ("autofs4: add new packet type for v5 communications"), it obvously tried quite hard to be word-size agnostic, and uses explicitly sized fields that are all correctly aligned. However, with the final "char name[NAME_MAX+1]" array at the end, the actual size of the structure ends up being not very well defined: because the struct isn't marked 'packed', doing a "sizeof()" on it will align the size of the struct up to the biggest alignment of the members it has. And despite all the members being the same, the alignment of them is different: a "__u64" has 4-byte alignment on x86-32, but native 8-byte alignment on x86-64. And while 'NAME_MAX+1' ends up being a nice round number (256), the name[] array starts out a 4-byte aligned. End result: the "packed" size of the structure is 300 bytes: 4-byte, but not 8-byte aligned. As a result, despite all the fields being in the same place on all architectures, sizeof() will round up that size to 304 bytes on architectures that have 8-byte alignment for u64. Note that this is *not* a problem for 32-bit compat mode on POWER, since there __u64 is 8-byte aligned even in 32-bit mode. But on x86, 32-bit and 64-bit alignment is different for 64-bit entities, and as a result the structure that has exactly the same layout has different sizes. So on x86-64, but no other architecture, we will just subtract 4 from the size of the structure when running in a compat task. That way we will write the properly sized packet that user mode expects. Not pretty. Sadly, this very subtle, and unnecessary, size difference has been encoded in user space that wants to read packets of *exactly* the right size, and will refuse to touch anything else. Reported-and-tested-by: Thomas Meyer <thomas@m3y3r.de> Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
autofs4: fix debug printk warning uncovered by cleanup The previous comit made the autofs4 debug printouts check types against the printout format, and uncovered this bug: fs/autofs4/waitq.c:106:2: warning: format ‘%08lx’ expects type ‘long unsigned int’, but argument 4 has type ‘autofs_wqt_t’ which is due to the insane type for wait_queue_token. That thing should be some fixed well-defined size (preferably just 'unsigned int' or 'u32') but for unexplained reasons it is randomly either 'unsigned long' or 'unsigned int' depending on the architecture. For now, cast it to 'unsigned long' for printing, the way we do elsewhere. Somebody else can try to explain the typedef mess. (There's a reason we don't support excessive use of typedefs in the kernel: it's usually just a good way of confusing yourself). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
autofs4 - remove autofs4_lock The autofs4_lock introduced by the rcu-walk changes has unnecessarily broad scope. The locking is better handled by the per-autofs super block lookup_lock. Signed-off-by: Ian Kent <raven@themaw.net> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
autofs4: Fix wait validation It is possible for the check in wait.c:validate_request() to return an incorrect result if the dentry that was mounted upon has changed during the callback. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs: dcache remove dcache_lock dcache_lock no longer protects anything. remove it. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
fs: Use rename lock and RCU for multi-step operations The remaining usages for dcache_lock is to allow atomic, multi-step read-side operations over the directory tree by excluding modifications to the tree. Also, to walk in the leaf->root direction in the tree where we don't have a natural d_lock ordering. This could be accomplished by taking every d_lock, but this would mean a huge number of locks and actually gets very tricky. Solve this instead by using the rename seqlock for multi-step read-side operations, retry in case of a rename so we don't walk up the wrong parent. Concurrent dentry insertions are not serialised against. Concurrent deletes are tricky when walking up the directory: our parent might have been deleted when dropping locks so also need to check and retry for that. We can also use the rename lock in cases where livelock is a worry (and it is introduced in subsequent patch). Signed-off-by: Nick Piggin <npiggin@kernel.dk>
autofs4: remove hashed check in validate_wait() The recent ->lookup() deadlock correction required the directory inode mutex to be dropped while waiting for expire completion. We were concerned about side effects from this change and one has been identified. I saw several error messages. They cause autofs to become quite confused and don't really point to the actual problem. Things like: handle_packet_missing_direct:1376: can't find map entry for (43,1827932) which is usually totally fatal (although in this case it wouldn't be except that I treat is as such because it normally is). do_mount_direct: direct trigger not valid or already mounted /test/nested/g3c/s1/ss1 which is recoverable, however if this problem is at play it can cause autofs to become quite confused as to the dependencies in the mount tree because mount triggers end up mounted multiple times. It's hard to accurately check for this over mounting case and automount shouldn't need to if the kernel module is doing its job. There was one other message, similar in consequence of this last one but I can't locate a log example just now. When checking if a mount has already completed prior to adding a new mount request to the wait queue we check if the dentry is hashed and, if so, if it is a mount point. But, if a mount successfully completed while we slept on the wait queue mutex the dentry must exist for the mount to have completed so the test is not really needed. Mounts can also be done on top of a global root dentry, so for the above case, where a mount request completes and the wait queue entry has already been removed, the hashed test returning false can cause an incorrect callback to the daemon. Also, d_mountpoint() is not sufficient to check if a mount has completed for the multi-mount case when we don't have a real mount at the base of the tree. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
autofs4: make autofs type usage explicit - the type assigned at mount when no type is given is changed from 0 to AUTOFS_TYPE_INDIRECT. This was done because 0 and AUTOFS_TYPE_INDIRECT were being treated implicitly as the same type. - previously, an offset mount had it's type set to AUTOFS_TYPE_DIRECT|AUTOFS_TYPE_OFFSET but the mount control re-implementation needs to be able distinguish all three types. So this was changed to make the type setting explicit. - a type AUTOFS_TYPE_ANY was added for use by the re-implementation when checking if a given path is a mountpoint. It's not really a type as we use this to ask if a given path is a mountpoint in the autofs_dev_ioctl_ismountpoint() function. - functions to set and test the autofs mount types have been added to improve readability and make the type usage explicit. - the mount type is used from user space for the mount control re-implementtion so, for consistency, all the definitions have been moved to the user space include file include/linux/auto_fs4.h. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CRED: Wrap task credential accesses in the autofs4 filesystem Wrap access to task credentials so that they can be separated more easily from the task_struct during the introduction of COW creds. Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id(). Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more sense to use RCU directly rather than a convenient wrapper; these will be addressed by later patches. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Ian Kent <raven@themaw.net> Cc: autofs@linux.kernel.org Signed-off-by: James Morris <jmorris@namei.org>
autofs4: track uid and gid of last mount requester Track the uid and gid of the last process to request a mount for on an autofs dentry. [akpm@linux-foundation.org: fix tpyo in comment] Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
autofs4: cleanup autofs mount type usage Usage of the AUTOFS_TYPE_* defines is a little confusing and appears inconsistent. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
autofs4: indirect dentry must almost always be positive We have been seeing mount requests comming to the automount daemon for keys of the form "<map key>/<non key directory>" which are lookups for invalid map keys. But we can check for this in the kernel module and return a fail immediately, without having to send a request to the daemon. It is possible to recognise these requests are invalid based on whether the request dentry is negative and its relation to the autofs file system root. For example, given the indirect multi-mount map entry: idm1 \ /mm1 <server>:/<path1> /mm2 <server>:/<path2> For a request to mount idm1, IS_ROOT((idm1)->d_parent) will be always be true and the dentry may be negative. But directories idm1/mm1 and idm1/mm2 will always be created as part of the mount request for idm1. So any mount request within idm1 itself must have a positive dentry otherwise the map key is invalid. In version 4 these multi-mount entries are all mounted and umounted as a single request and in version 5 the directories idm1/mm1 and idm1/mm2 are created and an autofs fs mounted on them to act as a mount trigger so the above is also true. This also holds true for the autofs version 4 pseudo direct mount feature. When this feature is used without the "--ghost" option automount(8) will create internal submounts as we go down the map key paths which are essentially normal indirect mounts for which the above holds. If the "--ghost" option is given the directories for map keys are created at daemon startup so valid map entries correspond to postive dentries in the autofs fs. autofs version 5 direct mount maps are similar except that the IS_ROOT check is not needed. This has been addressed in a previous patch tittled "autofs4 - detect invalid direct mount requests". For example, given the direct multi-mount map entry: /test/dm1 \ /mm1 <server>:/<path1> /mm2 <server>:/<path2> An autofs fs is mounted on /test/dm1 as a trigger mount and when a mount is triggered for /test/dm1, the multi-mount offset directories /test/dm1/mm1 and /test/dm1/mm2 are created and an autofs fs is mounted on them to act as mount triggers. So valid direct mount requests must always have a positive dentry if they correspond to a valid map entry. Signed-off-by: Ian Kent <raven@themaw.net> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
autofs4: detect invalid direct mount requests autofs v5 direct and offset mounts within an autofs filesystem are triggered by existing autofs triger mounts so the mount point dentry must be positive. If the mount point dentry is negative then the trigger doesn't exist so we can return fail immediately. Signed-off-by: Ian Kent <raven@themaw.net> Cc: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
autofs4: fix waitq memory leak If an autofs mount becomes catatonic before autofs4_wait_release() is called the wait queue counter will not be decremented down to zero and the entry will never be freed. There are also races decrementing the wait counter in the wait release function. To deal with this the counter needs to be updated while holding the wait queue mutex and waiters need to be woken up unconditionally when the wait is removed from the queue to ensure we eventually free the wait. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
autofs4: check kernel communication pipe is valid for write It is possible for an autofs mount to become catatonic (and for the daemon communication pipe to become NULL) after a wait has been initiallized but before the request has been sent to the daemon. We need to check for this before sending the request packet. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>