linux-stable.git/fs/nfsd, branch linux-3.16.y

nfsd: fix memory corruption caused by readdir

2019-07-09T21:04:11+00:00

commit b602345da6cbb135ba68cf042df8ec9a73da7981 upstream.

If the result of an NFSv3 readdir{,plus} request results in the
"offset" on one entry having to be split across 2 pages, and is sized
so that the next directory entry doesn't fit in the requested size,
then memory corruption can happen.

When encode_entry() is called after encoding the last entry that fits,
it notices that ->offset and ->offset1 are set, and so stores the
offset value in the two pages as required.  It clears ->offset1 but
*does not* clear ->offset.

Normally this omission doesn't matter as encode_entry_baggage() will
be called, and will set ->offset to a suitable value (not on a page
boundary).
But in the case where cd->buflen < elen and nfserr_toosmall is
returned, ->offset is not reset.

This means that nfsd3proc_readdirplus will see ->offset with a value 4
bytes before the end of a page, and ->offset1 set to NULL.
It will try to write 8bytes to ->offset.
If we are lucky, the next page will be read-only, and the system will
  BUG: unable to handle kernel paging request at...

If we are unlucky, some innocent page will have the first 4 bytes
corrupted.

nfsd3proc_readdir() doesn't even check for ->offset1, it just blindly
writes 8 bytes to the offset wherever it is.

Fix this by clearing ->offset after it is used, and copying the
->offset handling code from nfsd3_proc_readdirplus into
nfsd3_proc_readdir.

(Note that the commit hash in the Fixes tag is from the 'history'
 tree - this bug predates git).

Fixes: 0b1d57cf7654 ("[PATCH] kNFSd: Fix nfs3 dentry encoding")
Fixes-URL: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=0b1d57cf7654
Signed-off-by: NeilBrown 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Ben Hutchings

nfsd: silence sparse warning about accessing credentials

2018-11-20T18:05:28+00:00

commit ae4b884fc6316b3190be19448cea24b020c1cad6 upstream.

sparse says:

    fs/nfsd/auth.c:31:38: warning: incorrect type in argument 1 (different address spaces)
    fs/nfsd/auth.c:31:38:    expected struct cred const *cred
    fs/nfsd/auth.c:31:38:    got struct cred const [noderef] *real_cred

Add a new accessor for the ->real_cred and use that to fetch the
pointer. Accessing current->real_cred directly is actually quite safe
since we know that they can't go away so this is mostly a cosmetic fixup
to silence sparse.

Signed-off-by: Jeff Layton 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Ben Hutchings

nfsd: restrict rd_maxcount to svc_max_payload in nfsd_encode_readdir

2018-11-20T18:04:51+00:00

commit 9c2ece6ef67e9d376f32823086169b489c422ed0 upstream.

nfsd4_readdir_rsize restricts rd_maxcount to svc_max_payload when
estimating the size of the readdir reply, but nfsd_encode_readdir
restricts it to INT_MAX when encoding the reply.  This can result in log
messages like "kernel: RPC request reserved 32896 but used 1049444".

Restrict rd_dircount similarly (no reason it should be larger than
svc_max_payload).

Signed-off-by: Scott Mayhew 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Ben Hutchings

nfsd: auth: Fix gid sorting when rootsquash enabled

2018-03-03T15:51:59+00:00

commit 1995266727fa8143897e89b55f5d3c79aa828420 upstream.

Commit bdcf0a423ea1 ("kernel: make groups_sort calling a responsibility
group_info allocators") appears to break nfsd rootsquash in a pretty
major way.

It adds a call to groups_sort() inside the loop that copies/squashes
gids, which means the valid gids are sorted along with the following
garbage.  The net result is that the highest numbered valid gids are
replaced with any lower-valued garbage gids, possibly including 0.

We should sort only once, after filling in all the gids.

Fixes: bdcf0a423ea1 ("kernel: make groups_sort calling a responsibility ...")
Signed-off-by: Ben Hutchings 
Acked-by: J. Bruce Fields 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

kernel: make groups_sort calling a responsibility group_info allocators

2018-03-03T15:51:59+00:00

commit bdcf0a423ea1c40bbb40e7ee483b50fc8aa3d758 upstream.

In testing, we found that nfsd threads may call set_groups in parallel
for the same entry cached in auth.unix.gid, racing in the call of
groups_sort, corrupting the groups for that entry and leading to
permission denials for the client.

This patch:
 - Make groups_sort globally visible.
 - Move the call to groups_sort to the modifiers of group_info
 - Remove the call to groups_sort from set_groups

Link: http://lkml.kernel.org/r/20171211151420.18655-1-thiago.becker@gmail.com
Signed-off-by: Thiago Rafael Becker 
Reviewed-by: Matthew Wilcox 
Reviewed-by: NeilBrown 
Acked-by: "J. Bruce Fields" 
Cc: Al Viro 
Cc: Martin Schwidefsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

nfsd: Limit end of page list when decoding NFSv4 WRITE

2017-11-11T13:33:26+00:00

commit fc788f64f1f3eb31e87d4f53bcf1ab76590d5838 upstream.

When processing an NFSv4 WRITE operation, argp->end should never
point past the end of the data in the final page of the page list.
Otherwise, nfsd4_decode_compound can walk into uninitialized memory.

More critical, nfsd4_decode_write is failing to increment argp->pagelen
when it increments argp->pagelist.  This can cause later xdr decoders
to assume more data is available than really is, which can cause server
crashes on malformed requests.

Signed-off-by: Chuck Lever 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Ben Hutchings

ima: pass 'opened' flag to identify newly created files

2017-08-26T01:14:23+00:00

commit 3034a146820c26fe6da66a45f6340fe87fe0983a upstream.

Empty files and missing xattrs do not guarantee that a file was
just created.  This patch passes FILE_CREATED flag to IMA to
reliably identify new files.

Signed-off-by: Dmitry Kasatkin 
Signed-off-by: Mimi Zohar 
[bwh: Backported to 3.16: drop change to ima_fw_from_file()]
Signed-off-by: Ben Hutchings

nfsd: stricter decoding of write-like NFSv2/v3 ops

2017-06-05T20:17:23+00:00

commit 13bf9fbff0e5e099e2b6f003a0ab8ae145436309 upstream.

The NFSv2/v3 code does not systematically check whether we decode past
the end of the buffer.  This generally appears to be harmless, but there
are a few places where we do arithmetic on the pointers involved and
don't account for the possibility that a length could be negative.  Add
checks to catch these.

Reported-by: Tuomas Haanpää 
Reported-by: Ari Kauppi 
Reviewed-by: NeilBrown 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Ben Hutchings

nfsd4: minor NFSv2/v3 write decoding cleanup

2017-06-05T20:17:23+00:00

commit db44bac41bbfc0c0d9dd943092d8bded3c9db19b upstream.

Use a couple shortcuts that will simplify a following bugfix.

Signed-off-by: J. Bruce Fields 
[bwh: Backported to 3.16: in nfs3svc_decode_writeargs(), dlen doesn't include
 tail]
Signed-off-by: Ben Hutchings

nfsd: check for oversized NFSv2/v3 arguments

2017-06-05T20:17:23+00:00

commit e6838a29ecb484c97e4efef9429643b9851fba6e upstream.

A client can append random data to the end of an NFSv2 or NFSv3 RPC call
without our complaining; we'll just stop parsing at the end of the
expected data and ignore the rest.

Encoded arguments and replies are stored together in an array of pages,
and if a call is too large it could leave inadequate space for the
reply.  This is normally OK because NFS RPC's typically have either
short arguments and long replies (like READ) or long arguments and short
replies (like WRITE).  But a client that sends an incorrectly long reply
can violate those assumptions.  This was observed to cause crashes.

Also, several operations increment rq_next_page in the decode routine
before checking the argument size, which can leave rq_next_page pointing
well past the end of the page array, causing trouble later in
svc_free_pages.

So, following a suggestion from Neil Brown, add a central check to
enforce our expectation that no NFSv2/v3 call has both a large call and
a large reply.

As followup we may also want to rewrite the encoding routines to check
more carefully that they aren't running off the end of the page array.

We may also consider rejecting calls that have any extra garbage
appended.  That would be safer, and within our rights by spec, but given
the age of our server and the NFS protocol, and the fact that we've
never enforced this before, we may need to balance that against the
possibility of breaking some oddball client.

Reported-by: Tuomas Haanpää 
Reported-by: Ari Kauppi 
Reviewed-by: NeilBrown 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Ben Hutchings