nfsd: check permissions when setting ACLs

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[ Upstream commit 999653786d ]

Use set_posix_acl, which includes proper permission checks, instead of
calling ->set_acl directly.  Without this anyone may be able to grant
themselves permissions to a file by setting the ACL.

Lock the inode to make the new checks atomic with respect to set_acl.
(Also, nfsd was the only caller of set_acl not locking the inode, so I
suspect this may fix other races.)

This also simplifies the code, and ensures our ACLs are checked by
posix_acl_valid.

The permission checks and the inode locking were lost with commit
4ac7249e, which changed nfsd to use the set_acl inode operation directly
instead of going through xattr handlers.

Reported-by: David Sinquin <david@sinquin.eu>
[agreunba@redhat.com: use set_posix_acl]
Fixes: 4ac7249e
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

...

This commit is contained in:

Ben Hutchings 2016-06-22 19:43:35 +01:00 • committed by Sasha Levin

parent 6abbd53f83

commit 3e287c23ef

3 changed files with 25 additions and 27 deletions

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20

fs/nfsd/nfs2acl.c

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18

fs/nfsd/nfs3acl.c

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16

fs/nfsd/nfs4acl.c

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