kernel/linux.git/fs/fuse, branch linux-5.11.y

cuse: prevent clone

2021-05-19T08:29:32+00:00

[ Upstream commit 8217673d07256b22881127bf50dce874d0e51653 ] For cloned connections cuse_channel_release() will be called more than once, resulting in use after free. Prevent device cloning for CUSE, which does not make sense at this point, and highly unlikely to be used in real life. Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

virtiofs: fix userns

2021-05-19T08:29:32+00:00

[ Upstream commit 0a7419c68a45d2d066b996be5087aa2d07ce80eb ] get_user_ns() is done twice (once in virtio_fs_get_tree() and once in fuse_conn_init()), resulting in a reference leak. Also looks better to use fsc->user_ns (which *should* be the current_user_ns() at this point). Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

fuse: invalidate attrs when page writeback completes

2021-05-19T08:29:32+00:00

[ Upstream commit 3466958beb31a8e9d3a1441a34228ed088b84f3e ] In fuse when a direct/write-through write happens we invalidate attrs because that might have updated mtime/ctime on server and cached mtime/ctime will be stale. What about page writeback path. Looks like we don't invalidate attrs there. To be consistent, invalidate attrs in writeback path as well. Only exception is when writeback_cache is enabled. In that case we strust local mtime/ctime and there is no need to invalidate attrs. Recently users started experiencing failure of xfstests generic/080, geneirc/215 and generic/614 on virtiofs. This happened only newer "stat" utility and not older one. This patch fixes the issue. So what's the root cause of the issue. Here is detailed explanation. generic/080 test does mmap write to a file, closes the file and then checks if mtime has been updated or not. When file is closed, it leads to flushing of dirty pages (and that should update mtime/ctime on server). But we did not explicitly invalidate attrs after writeback finished. Still generic/080 passed so far and reason being that we invalidated atime in fuse_readpages_end(). This is called in fuse_readahead() path and always seems to trigger before mmaped write. So after mmaped write when lstat() is called, it sees that atleast one of the fields being asked for is invalid (atime) and that results in generating GETATTR to server and mtime/ctime also get updated and test passes. But newer /usr/bin/stat seems to have moved to using statx() syscall now (instead of using lstat()). And statx() allows it to query only ctime or mtime (and not rest of the basic stat fields). That means when querying for mtime, fuse_update_get_attr() sees that mtime is not invalid (only atime is invalid). So it does not generate a new GETATTR and fill stat with cached mtime/ctime. And that means updated mtime is not seen by xfstest and tests start failing. Invalidating attrs after writeback completion should solve this problem in a generic manner. Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

fuse: fix write deadlock

2021-05-12T06:37:34+00:00

commit 4f06dd92b5d0a6f8eec6a34b8d6ef3e1f4ac1e10 upstream. There are two modes for write(2) and friends in fuse: a) write through (update page cache, send sync WRITE request to userspace) b) buffered write (update page cache, async writeout later) The write through method kept all the page cache pages locked that were used for the request. Keeping more than one page locked is deadlock prone and Qian Cai demonstrated this with trinity fuzzing. The reason for keeping the pages locked is that concurrent mapped reads shouldn't try to pull possibly stale data into the page cache. For full page writes, the easy way to fix this is to make the cached page be the authoritative source by marking the page PG_uptodate immediately. After this the page can be safely unlocked, since mapped/cached reads will take the written data from the cache. Concurrent mapped writes will now cause data in the original WRITE request to be updated; this however doesn't cause any data inconsistency and this scenario should be exceedingly rare anyway. If the WRITE request returns with an error in the above case, currently the page is not marked uptodate; this means that a concurrent read will always read consistent data. After this patch the page is uptodate between writing to the cache and receiving the error: there's window where a cached read will read the wrong data. While theoretically this could be a regression, it is unlikely to be one in practice, since this is normal for buffered writes. In case of a partial page write to an already uptodate page the locking is also unnecessary, with the above caveats. Partial write of a not uptodate page still needs to be handled. One way would be to read the complete page before doing the write. This is not possible, since it might break filesystems that don't expect any READ requests when the file was opened O_WRONLY. The other solution is to serialize the synchronous write with reads from the partial pages. The easiest way to do this is to keep the partial pages locked. The problem is that a write() may involve two such pages (one head and one tail). This patch fixes it by only locking the partial tail page. If there's a partial head page as well, then split that off as a separate WRITE request. Reported-by: Qian Cai Link: https://lore.kernel.org/linux-fsdevel/4794a3fa3742a5e84fb0f934944204b55730829b.camel@lca.pw/ Fixes: ea9b9907b82a ("fuse: implement perform_write") Cc: # v2.6.26 Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

virtiofs: fix memory leak in virtio_fs_probe()

2021-05-12T06:37:31+00:00

commit c79c5e0178922a9e092ec8fed026750f39dcaef4 upstream. When accidentally passing twice the same tag to qemu, kmemleak ended up reporting a memory leak in virtiofs. Also, looking at the log I saw the following error (that's when I realised the duplicated tag): virtiofs: probe of virtio5 failed with error -17 Here's the kmemleak log for reference: unreferenced object 0xffff888103d47800 (size 1024): comm "systemd-udevd", pid 118, jiffies 4294893780 (age 18.340s) hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... ff ff ff ff ff ff ff ff 80 90 02 a0 ff ff ff ff ................ backtrace: [<000000000ebb87c1>] virtio_fs_probe+0x171/0x7ae [virtiofs] [<00000000f8aca419>] virtio_dev_probe+0x15f/0x210 [<000000004d6baf3c>] really_probe+0xea/0x430 [<00000000a6ceeac8>] device_driver_attach+0xa8/0xb0 [<00000000196f47a7>] __driver_attach+0x98/0x140 [<000000000b20601d>] bus_for_each_dev+0x7b/0xc0 [<00000000399c7b7f>] bus_add_driver+0x11b/0x1f0 [<0000000032b09ba7>] driver_register+0x8f/0xe0 [<00000000cdd55998>] 0xffffffffa002c013 [<000000000ea196a2>] do_one_initcall+0x64/0x2e0 [<0000000008f727ce>] do_init_module+0x5c/0x260 [<000000003cdedab6>] __do_sys_finit_module+0xb5/0x120 [<00000000ad2f48c6>] do_syscall_64+0x33/0x40 [<00000000809526b5>] entry_SYSCALL_64_after_hwframe+0x44/0xae Cc: stable@vger.kernel.org Signed-off-by: Luis Henriques Fixes: a62a8ef9d97d ("virtio-fs: add virtiofs filesystem") Reviewed-by: Stefan Hajnoczi Reviewed-by: Vivek Goyal Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

virtiofs: Fail dax mount if device does not support it

2021-04-07T13:02:23+00:00

[ Upstream commit 3f9b9efd82a84f27e95d0414f852caf1fa839e83 ] Right now "mount -t virtiofs -o dax myfs /mnt/virtiofs" succeeds even if filesystem deivce does not have a cache window and hence DAX can't be supported. This gives a false sense to user that they are using DAX with virtiofs but fact of the matter is that they are not. Fix this by returning error if dax can't be supported and user has asked for it. Signed-off-by: Vivek Goyal Reviewed-by: Stefan Hajnoczi Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

fuse: fix live lock in fuse_iget()

2021-03-20T09:51:14+00:00

commit 775c5033a0d164622d9d10dd0f0a5531639ed3ed upstream. Commit 5d069dbe8aaf ("fuse: fix bad inode") replaced make_bad_inode() in fuse_iget() with a private implementation fuse_make_bad(). The private implementation fails to remove the bad inode from inode cache, so the retry loop with iget5_locked() finds the same bad inode and marks it bad forever. kmsg snip: [ ] rcu: INFO: rcu_sched self-detected stall on CPU ... [ ] ? bit_wait_io+0x50/0x50 [ ] ? fuse_init_file_inode+0x70/0x70 [ ] ? find_inode.isra.32+0x60/0xb0 [ ] ? fuse_init_file_inode+0x70/0x70 [ ] ilookup5_nowait+0x65/0x90 [ ] ? fuse_init_file_inode+0x70/0x70 [ ] ilookup5.part.36+0x2e/0x80 [ ] ? fuse_init_file_inode+0x70/0x70 [ ] ? fuse_inode_eq+0x20/0x20 [ ] iget5_locked+0x21/0x80 [ ] ? fuse_inode_eq+0x20/0x20 [ ] fuse_iget+0x96/0x1b0 Fixes: 5d069dbe8aaf ("fuse: fix bad inode") Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

fuse: fix bad inode

2020-12-10T14:33:14+00:00

Jan Kara's analysis of the syzbot report (edited): The reproducer opens a directory on FUSE filesystem, it then attaches dnotify mark to the open directory. After that a fuse_do_getattr() call finds that attributes returned by the server are inconsistent, and calls make_bad_inode() which, among other things does: inode->i_mode = S_IFREG; This then confuses dnotify which doesn't tear down its structures properly and eventually crashes. Avoid calling make_bad_inode() on a live inode: switch to a private flag on the fuse inode. Also add the test to ops which the bad_inode_ops would have caught. This bug goes back to the initial merge of fuse in 2.6.14... Reported-by: syzbot+f427adf9324b92652ccc@syzkaller.appspotmail.com Signed-off-by: Miklos Szeredi Tested-by: Jan Kara Cc:

fuse: support SB_NOSEC flag to improve write performance

2020-11-11T16:22:33+00:00

Virtiofs can be slow with small writes if xattr are enabled and we are doing cached writes (No direct I/O). Ganesh Mahalingam noticed this. Some debugging showed that file_remove_privs() is called in cached write path on every write. And everytime it calls security_inode_need_killpriv() which results in call to __vfs_getxattr(XATTR_NAME_CAPS). And this goes to file server to fetch xattr. This extra round trip for every write slows down writes tremendously. Normally to avoid paying this penalty on every write, vfs has the notion of caching this information in inode (S_NOSEC). So vfs sets S_NOSEC, if filesystem opted for it using super block flag SB_NOSEC. And S_NOSEC is cleared when setuid/setgid bit is set or when security xattr is set on inode so that next time a write happens, we check inode again for clearing setuid/setgid bits as well clear any security.capability xattr. This seems to work well for local file systems but for remote file systems it is possible that VFS does not have full picture and a different client sets setuid/setgid bit or security.capability xattr on file and that means VFS information about S_NOSEC on another client will be stale. So for remote filesystems SB_NOSEC was disabled by default. Commit 9e1f1de02c22 ("more conservative S_NOSEC handling") mentioned that these filesystems can still make use of SB_NOSEC as long as they clear S_NOSEC when they are refreshing inode attriutes from server. So this patch tries to enable SB_NOSEC on fuse (regular fuse as well as virtiofs). And clear SB_NOSEC when we are refreshing inode attributes. This is enabled only if server supports FUSE_HANDLE_KILLPRIV_V2. This says that server will clear setuid/setgid/security.capability on chown/truncate/write as apporpriate. This should provide tighter coherency because now suid/sgid/ security.capability will be cleared even if fuse client cache has not seen these attrs. Basic idea is that fuse client will trigger suid/sgid/security.capability clearing based on its attr cache. But even if cache has gone stale, it is fine because FUSE_HANDLE_KILLPRIV_V2 will make sure WRITE clear suid/sgid/security.capability. We make this change only if server supports FUSE_HANDLE_KILLPRIV_V2. This should make sure that existing filesystems which might be relying on seucurity.capability always being queried from server are not impacted. This tighter coherency relies on WRITE showing up on server (and not being cached in guest). So writeback_cache mode will not provide that tight coherency and it is not recommended to use two together. Having said that it might work reasonably well for lot of use cases. This change improves random write performance very significantly. Running virtiofsd with cache=auto and following fio command: fio --ioengine=libaio --direct=1 --name=test --filename=/mnt/virtiofs/random_read_write.fio --bs=4k --iodepth=64 --size=4G --readwrite=randwrite Bandwidth increases from around 50MB/s to around 250MB/s as a result of applying this patch. So improvement is very significant. Link: https://github.com/kata-containers/runtime/issues/2815 Reported-by: "Mahalingam, Ganesh" Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi

fuse: add a flag FUSE_OPEN_KILL_SUIDGID for open() request

2020-11-11T16:22:33+00:00

With FUSE_HANDLE_KILLPRIV_V2 support, server will need to kill suid/sgid/ security.capability on open(O_TRUNC), if server supports FUSE_ATOMIC_O_TRUNC. But server needs to kill suid/sgid only if caller does not have CAP_FSETID. Given server does not have this information, client needs to send this info to server. So add a flag FUSE_OPEN_KILL_SUIDGID to fuse_open_in request which tells server to kill suid/sgid (only if group execute is set). This flag is added to the FUSE_OPEN request, as well as the FUSE_CREATE request if the create was non-exclusive, since that might result in an existing file being opened/truncated. Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi