linux-stable.git/fs/fuse/dir.c, branch linux-3.16.y

fuse: verify nlink

2020-02-11T20:03:38+00:00

commit c634da718db9b2fac201df2ae1b1b095344ce5eb upstream.

When adding a new hard link, make sure that i_nlink doesn't overflow.

Fixes: ac45d61357e8 ("fuse: fix nlink after unlink")
Signed-off-by: Miklos Szeredi 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

fuse: verify attributes

2020-02-11T20:03:37+00:00

commit eb59bd17d2fa6e5e84fba61a5ebdea984222e6d5 upstream.

If a filesystem returns negative inode sizes, future reads on the file were
causing the cpu to spin on truncate_pagecache.

Create a helper to validate the attributes.  This now does two things:

 - check the file mode
 - check if the file size fits in i_size without overflowing

Reported-by: Arijit Banerjee 
Fixes: d8a5ba45457e ("[PATCH] FUSE - core")
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

fuse: flush dirty data/metadata before non-truncate setattr

2019-12-19T15:58:42+00:00

commit b24e7598db62386a95a3c8b9c75630c5d56fe077 upstream.

If writeback cache is enabled, then writes might get reordered with
chmod/chown/utimes.  The problem with this is that performing the write in
the fuse daemon might itself change some of these attributes.  In such case
the following sequence of operations will result in file ending up with the
wrong mode, for example:

  int fd = open ("suid", O_WRONLY|O_CREAT|O_EXCL);
  write (fd, "1", 1);
  fchown (fd, 0, 0);
  fchmod (fd, 04755);
  close (fd);

This patch fixes this by flushing pending writes before performing
chown/chmod/utimes.

Reported-by: Giuseppe Scrivano 
Tested-by: Giuseppe Scrivano 
Fixes: 4d99ff8f12eb ("fuse: Turn writeback cache on")
Signed-off-by: Miklos Szeredi 
Signed-off-by: Ben Hutchings

fuse: continue to send FUSE_RELEASEDIR when FUSE_OPEN returns ENOSYS

2019-02-11T17:54:24+00:00

commit 2e64ff154ce6ce9a8dc0f9556463916efa6ff460 upstream.

When FUSE_OPEN returns ENOSYS, the no_open bit is set on the connection.

Because the FUSE_RELEASE and FUSE_RELEASEDIR paths share code, this
incorrectly caused the FUSE_RELEASEDIR request to be dropped and never sent
to userspace.

Pass an isdir bool to distinguish between FUSE_RELEASE and FUSE_RELEASEDIR
inside of fuse_file_put.

Fixes: 7678ac50615d ("fuse: support clients that don't implement 'open'")
Signed-off-by: Chad Austin 
Signed-off-by: Miklos Szeredi 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

fuse: cleanup fuse_file refcounting

2019-02-11T17:54:24+00:00

commit 267d84449f52349ee252db684ed95ede18e51744 upstream.

struct fuse_file is stored in file->private_data.  Make this always be a
counting reference for consistency.

This also allows fuse_sync_release() to call fuse_file_put() instead of
partially duplicating its functionality.

Signed-off-by: Miklos Szeredi 
[bwh: Backported to 3.16: force and background flags are bitfields]
Signed-off-by: Ben Hutchings

fuse: atomic_o_trunc should truncate pagecache

2018-11-20T18:04:46+00:00

commit df0e91d488276086bc07da2e389986cae0048c37 upstream.

Fuse has an "atomic_o_trunc" mode, where userspace filesystem uses the
O_TRUNC flag in the OPEN request to truncate the file atomically with the
open.

In this mode there's no need to send a SETATTR request to userspace after
the open, so fuse_do_setattr() checks this mode and returns.  But this
misses the important step of truncating the pagecache.

Add the missing parts of truncation to the ATTR_OPEN branch.

Reported-by: Chad Austin 
Fixes: 6ff958edbf39 ("fuse: add atomic open+truncate support")
Signed-off-by: Miklos Szeredi 
Signed-off-by: Ben Hutchings

fuse: fix READDIRPLUS skipping an entry

2018-01-01T20:51:59+00:00

commit c6cdd51404b7ac12dd95173ddfc548c59ecf037f upstream.

Marios Titas running a Haskell program noticed a problem with fuse's
readdirplus: when it is interrupted by a signal, it skips one directory
entry.

The reason is that fuse erronously updates ctx->pos after a failed
dir_emit().

The issue originates from the patch adding readdirplus support.

Reported-by: Jakob Unterwurzacher 
Tested-by: Marios Titas 
Signed-off-by: Miklos Szeredi 
Fixes: 0b05b18381ee ("fuse: implement NFS-like readdirplus support")
Signed-off-by: Ben Hutchings

fuse: fix clearing suid, sgid for chown()

2017-02-23T03:54:43+00:00

commit c01638f5d919728f565bf8b5e0a6a159642df0d9 upstream.

Basically, the pjdfstests set the ownership of a file to 06555, and then
chowns it (as root) to a new uid/gid. Prior to commit a09f99eddef4 ("fuse:
fix killing s[ug]id in setattr"), fuse would send down a setattr with both
the uid/gid change and a new mode.  Now, it just sends down the uid/gid
change.

Technically this is NOTABUG, since POSIX doesn't _require_ that we clear
these bits for a privileged process, but Linux (wisely) has done that and I
think we don't want to change that behavior here.

This is caused by the use of should_remove_suid(), which will always return
0 when the process has CAP_FSETID.

In fact we really don't need to be calling should_remove_suid() at all,
since we've already been indicated that we should remove the suid, we just
don't want to use a (very) stale mode for that.

This patch should fix the above as well as simplify the logic.

Reported-by: Jeff Layton 
Signed-off-by: Miklos Szeredi 
Fixes: a09f99eddef4 ("fuse: fix killing s[ug]id in setattr")
Reviewed-by: Jeff Layton 
[bwh: Backported to 3.16: adjust context, indentation]
Signed-off-by: Ben Hutchings

fuse: listxattr: verify xattr list

2017-02-23T03:54:07+00:00

commit cb3ae6d25a5471be62bfe6ac1fccc0e91edeaba0 upstream.

Make sure userspace filesystem is returning a well formed list of xattr
names (zero or more nonzero length, null terminated strings).

[Michael Theall: only verify in the nonzero size case]

Signed-off-by: Miklos Szeredi 
[bwh: Backported to 3.16: adjust context, indentation]
Signed-off-by: Ben Hutchings

fuse: fix killing s[ug]id in setattr

2017-02-23T03:54:07+00:00

commit a09f99eddef44035ec764075a37bace8181bec38 upstream.

Fuse allowed VFS to set mode in setattr in order to clear suid/sgid on
chown and truncate, and (since writeback_cache) write.  The problem with
this is that it'll potentially restore a stale mode.

The poper fix would be to let the filesystems do the suid/sgid clearing on
the relevant operations.  Possibly some are already doing it but there's no
way we can detect this.

So fix this by refreshing and recalculating the mode.  Do this only if
ATTR_KILL_S[UG]ID is set to not destroy performance for writes.  This is
still racy but the size of the window is reduced.

Signed-off-by: Miklos Szeredi 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings