wireguard-linux/fs/afs/dir.c, branch jd/unified-crypt-queue

afs: Fix afs_d_validate() to set the right directory version

2020-04-13T14:09:01Z

If a dentry's version is somewhere between invalid_before and the current directory version, we should be setting it forward to the current version, not backwards to the invalid_before version. Note that we're only doing this at all because dentry::d_fsdata isn't large enough on a 32-bit system. Fix this by using a separate variable for invalid_before so that we don't accidentally clobber the current dir version. Fixes: a4ff7401fbfa ("afs: Keep track of invalid-before version for dentry coherency") Signed-off-by: David Howells

afs: Fix race between post-modification dir edit and readdir/d_revalidate

2020-04-13T14:09:01Z

AFS directories are retained locally as a structured file, with lookup being effected by a local search of the file contents. When a modification (such as mkdir) happens, the dir file content is modified locally rather than redownloading the directory. The directory contents are accessed in a number of ways, with a number of different locks schemes: (1) Download of contents - dvnode->validate_lock/write in afs_read_dir(). (2) Lookup and readdir - dvnode->validate_lock/read in afs_dir_iterate(), downgrading from (1) if necessary. (3) d_revalidate of child dentry - dvnode->validate_lock/read in afs_do_lookup_one() downgrading from (1) if necessary. (4) Edit of dir after modification - page locks on individual dir pages. Unfortunately, because (4) uses different locking scheme to (1) - (3), nothing protects against the page being scanned whilst the edit is underway. Even download is not safe as it doesn't lock the pages - relying instead on the validate_lock to serialise as a whole (the theory being that directory contents are treated as a block and always downloaded as a block). Fix this by write-locking dvnode->validate_lock around the edits. Care must be taken in the rename case as there may be two different dirs - but they need not be locked at the same time. In any case, once the lock is taken, the directory version must be rechecked, and the edit skipped if a later version has been downloaded by revalidation (there can't have been any local changes because the VFS holds the inode lock, but there can have been remote changes). Fixes: 63a4681ff39c ("afs: Locally edit directory data for mkdir/create/unlink/...") Signed-off-by: David Howells

afs: Fix rename operation status delivery

2020-04-13T14:09:01Z

The afs_deliver_fs_rename() and yfs_deliver_fs_rename() functions both only decode the second file status returned unless the parent directories are different - unfortunately, this means that the xdr pointer isn't advanced and the volsync record will be read incorrectly in such an instance. Fix this by always decoding the second status into the second status/callback block which wasn't being used if the dirs were the same. The afs_update_dentry_version() calls that update the directory data version numbers on the dentries can then unconditionally use the second status record as this will always reflect the state of the destination dir (the two records will be identical if the destination dir is the same as the source dir) Fixes: 260a980317da ("[AFS]: Add "directory write" support.") Fixes: 30062bd13e36 ("afs: Implement YFS support in the fs client") Signed-off-by: David Howells

afs: Fix afs_lookup() to not clobber the version on a new dentry

2020-01-14T17:40:06Z

Fix afs_lookup() to not clobber the version set on a new dentry by afs_do_lookup() - especially as it's using the wrong version of the version (we need to use the one given to us by whatever op the dir contents correspond to rather than what's in the afs_vnode). Fixes: 9dd0b82ef530 ("afs: Fix missing dentry data version updating") Signed-off-by: David Howells Signed-off-by: Linus Torvalds

afs: Fix use-after-loss-of-ref

2020-01-14T17:40:06Z

afs_lookup() has a tracepoint to indicate the outcome of d_splice_alias(), passing it the inode to retrieve the fid from. However, the function gave up its ref on that inode when it called d_splice_alias(), which may have failed and dropped the inode. Fix this by caching the fid. Fixes: 80548b03991f ("afs: Add more tracepoints") Reported-by: Al Viro Signed-off-by: David Howells Signed-off-by: Linus Torvalds

afs: Fix race in commit bulk status fetch

2019-11-15T18:28:02Z

When a lookup is done, the afs filesystem will perform a bulk status-fetch operation on the requested vnode (file) plus the next 49 other vnodes from the directory list (in AFS, directory contents are downloaded as blobs and parsed locally). When the results are received, it will speculatively populate the inode cache from the extra data. However, if the lookup races with another lookup on the same directory, but for a different file - one that's in the 49 extra fetches, then if the bulk status-fetch operation finishes first, it will try and update the inode from the other lookup. If this other inode is still in the throes of being created, however, this will cause an assertion failure in afs_apply_status(): BUG_ON(test_bit(AFS_VNODE_UNSET, &vnode->flags)); on or about fs/afs/inode.c:175 because it expects data to be there already that it can compare to. Fix this by skipping the update if the inode is being created as the creator will presumably set up the inode with the same information. Fixes: 39db9815da48 ("afs: Fix application of the results of a inline bulk status fetch") Signed-off-by: David Howells Reviewed-by: Marc Dionne Signed-off-by: Linus Torvalds

afs: Support RCU pathwalk

2019-09-02T10:43:54Z

Make afs_permission() and afs_d_revalidate() do initial checks in RCU-mode pathwalk to reduce latency in pathwalk elements that get done multiple times. We don't need to query the server unless we've received a notification from it that something has changed or the callback has expired. This requires that we can request a key and check permits under RCU conditions if we need to. Signed-off-by: David Howells

afs: Fix possible oops in afs_lookup trace event

2019-08-22T12:33:26Z

The afs_lookup trace event can cause the following: [ 216.576777] BUG: kernel NULL pointer dereference, address: 000000000000023b [ 216.576803] #PF: supervisor read access in kernel mode [ 216.576813] #PF: error_code(0x0000) - not-present page ... [ 216.576913] RIP: 0010:trace_event_raw_event_afs_lookup+0x9e/0x1c0 [kafs] If the inode from afs_do_lookup() is an error other than ENOENT, or if it is ENOENT and afs_try_auto_mntpt() returns an error, the trace event will try to dereference the error pointer as a valid pointer. Use IS_ERR_OR_NULL to only pass a valid pointer for the trace, or NULL. Ideally the trace would include the error value, but for now just avoid the oops. Fixes: 80548b03991f ("afs: Add more tracepoints") Signed-off-by: Marc Dionne Signed-off-by: David Howells

afs: Fix missing dentry data version updating

2019-07-30T13:38:52Z

In the in-kernel afs filesystem, the d_fsdata dentry field is used to hold the data version of the parent directory when it was created or when d_revalidate() last caused it to be updated. This is compared to the ->invalid_before field in the directory inode, rather than the actual data version number, thereby allowing changes due to local edits to be ignored. Only if the server data version gets bumped unexpectedly (eg. by a competing client), do we need to revalidate stuff. However, the d_fsdata field should also be updated if an rpc op is performed that modifies that particular dentry. Such ops return the revised data version of the directory(ies) involved, so we should use that. This is particularly problematic for rename, since a dentry from one directory may be moved directly into another directory (ie. mv a/x b/x). It would then be sporting the wrong data version - and if this is in the future, for the destination directory, revalidations would be missed, leading to foreign renames and hard-link deletion being missed. Fix this by the following means: (1) Return the data version number from operations that read the directory contents - if they issue the read. This starts in afs_dir_iterate() and is used, ignored or passed back by its callers. (2) In afs_lookup*(), set the dentry version to the version returned by (1) before d_splice_alias() is called and the dentry published. (3) In afs_d_revalidate(), set the dentry version to that returned from (1) if an rpc call was issued. This means that if a parallel procedure, such as mkdir(), modifies the directory, we won't accidentally use the data version from that. (4) In afs_{mkdir,create,link,symlink}(), set the new dentry's version to the directory data version before d_instantiate() is called. (5) In afs_{rmdir,unlink}, update the target dentry's version to the directory data version as soon as we've updated the directory inode. (6) In afs_rename(), we need to unhash the old dentry before we start so that we don't get afs_d_revalidate() reverting the version change in cross-directory renames. We then need to set both the old and the new dentry versions the data version of the new directory before we call d_move() as d_move() will rehash them. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: David Howells

afs: Only update d_fsdata if different in afs_d_revalidate()

2019-07-30T13:38:51Z

In the in-kernel afs filesystem, d_fsdata is set with the data version of the parent directory. afs_d_revalidate() will update this to the current directory version, but it shouldn't do this if it the value it read from d_fsdata is the same as no lock is held and cmpxchg() is not used. Fix the code to only change the value if it is different from the current directory version. Fixes: 260a980317da ("[AFS]: Add "directory write" support.") Signed-off-by: David Howells