atomic_t variables are currently used to implement reference
counters with the following properties:
 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable nfs4_file.fi_ref is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NDavid Windsor <dwindsor@gmail.com>
Reviewed-by: NHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: NElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

atomic_t variables are currently used to implement reference
counters with the following properties:
 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable nfs4_cntl_odstate.co_odcount is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NDavid Windsor <dwindsor@gmail.com>
Reviewed-by: NHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: NElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

atomic_t variables are currently used to implement reference
counters with the following properties:
 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable nfs4_stid.sc_count is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NDavid Windsor <dwindsor@gmail.com>
Reviewed-by: NHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: NElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

The spec allows us to return NFS4ERR_SEQ_FALSE_RETRY if we notice that
the client is making a call that matches a previous (slot, seqid) pair
but that *isn't* actually a replay, because some detail of the call
doesn't actually match the previous one.

Catching every such case is difficult, but we may as well catch a few
easy ones.  This also handles the case described in the previous patch,
in a different way.

The spec does however require us to catch the case where the difference
is in the rpc credentials.  This prevents somebody from snooping another
user's replies by fabricating retries.

(But the practical value of the attack is limited by the fact that the
replies with the most sensitive data are READ replies, which are not
normally cached.)
Tested-by: NOlga Kornievskaia <aglo@umich.edu>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Currently our handling of 4.1+ requests without "cachethis" set is
confusing and not quite correct.

Suppose a client sends a compound consisting of only a single SEQUENCE
op, and it matches the seqid in a session slot (so it's a retry), but
the previous request with that seqid did not have "cachethis" set.

The obvious thing to do might be to return NFS4ERR_RETRY_UNCACHED_REP,
but the protocol only allows that to be returned on the op following the
SEQUENCE, and there is no such op in this case.

The protocol permits us to cache replies even if the client didn't ask
us to.  And it's easy to do so in the case of solo SEQUENCE compounds.

So, when we get a solo SEQUENCE, we can either return the previously
cached reply or NFSERR_SEQ_FALSE_RETRY if we notice it differs in some
way from the original call.

Currently, we're returning a corrupt reply in the case a solo SEQUENCE
matches a previous compound with more ops.  This actually matters
because the Linux client recently started doing this as a way to recover
from lost replies to idempotent operations in the case the process doing
the original reply was killed: in that case it's difficult to keep the
original arguments around to do a real retry, and the client no longer
cares what the result is anyway, but it would like to make sure that the
slot's sequence id has been incremented, and the solo SEQUENCE assures
that: if the server never got the original reply, it will increment the
sequence id.  If it did get the original reply, it won't increment, and
nothing else that about the reply really matters much.  But we can at
least attempt to return valid xdr!
Tested-by: NOlga Kornievskaia <aglo@umich.edu>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Using the ARRAY_SIZE macro improves the readability of the code.

Found with Coccinelle with the following semantic patch:
@r depends on (org || report)@
type T;
T[] E;
position p;
@@
(
 (sizeof(E)@p /sizeof(*E))
|
 (sizeof(E)@p /sizeof(E[...]))
|
 (sizeof(E)@p /sizeof(T))
)
Signed-off-by: NJérémy Lefaure <jeremy.lefaure@lse.epita.fr>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Instead of granting client's full requests until we hit our DRC size
limit and then failing CREATE_SESSIONs (and hence mounts) completely,
start granting clients smaller slot tables as we approach the limit.

The factor chosen here is pretty much arbitrary.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

An NFSv4.1+ client negotiates the size of its duplicate reply cache size
in the initial CREATE_SESSION request.  The server preallocates the
memory for the duplicate reply cache to ensure that we'll never fail to
record the response to a nonidempotent operation.

To prevent a few CREATE_SESSIONs from consuming all of memory we set an
upper limit based on nr_free_buffer_pages().  1/2^10 has been too
limiting in practice; 1/2^7 is still less than one percent.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

These checks should have already be done centrally in
nfsd4_proc_compound, the checks in each individual operation are
unnecessary.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Since the beginning, svcsock has built a received RPC Call message
by populating the xdr_buf's head, then placing the remaining
message bytes in the xdr_buf's page list. The xdr_buf's tail is
never populated.

This means that an NFSv4 COMPOUND containing an NFS WRITE operation
plus trailing operations has a page list that contains the WRITE
data payload followed by the trailing operations. NFSv4 XDR decoders
will not look in the xdr_buf's tail, ever, because svcsock never put
anything there.

To support transports that can pass the write payload in the
xdr_buf's pagelist and trailing content in the xdr_buf's tail,
introduce logic in READ_BUF that switches to the xdr_buf's tail vec
when the decoder runs out of content in rq_arg.pages.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

[AV: added missing annotations in syscalls.h/compat.h]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Close an attack vector by moving the arrays of per-server methods to
read-only memory.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Close an attack vector by moving the arrays of encoding and decoding
methods to read-only memory.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

With a few exceptions, most individual encoders don't handle error
cases.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Most encoders do nothing in the error case.  But they can still screw
things up in that case: most errors happen very early in rpc processing,
possibly before argument fields are filled in and bounds-tested, so
encoders that do anything other than immediately bail on error can
easily crash in odd error cases.

So just handle errors centrally most of the time to remove the chance of
error.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Run a separate ->op_release function if necessary instead of depending
on the xdr encoder to do this.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Trivial cleanup, no change in behavior.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

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: NChuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

I want code in nfs4xdr.c to have access to this stuff.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

The offset of the entry in struct rpc_version has to match the version
number.
Reported-by: NDave Jones <davej@codemonkey.org.uk>
Fixes: 1c5876dd ("sunrpc: move p_count out of struct rpc_procinfo")
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Reported-by: NDave Jones <davej@codemonkey.org.uk>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

nfsd4_ops contains function pointers, and marking it as constant avoids
it being able to be used as an attach vector for code injections.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NTrond Myklebust <trond.myklebust@primarydata.com>

struct svc_procinfo contains function pointers, and marking it as
constant avoids it being able to be used as an attach vector for
code injections.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

pc_count is the only writeable memeber of struct svc_procinfo, which is
a good candidate to be const-ified as it contains function pointers.

This patch moves it into out out struct svc_procinfo, and into a
separate writable array that is pointed to by struct svc_version.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Pass union nfsd4_op_u to the op_func callbacks instead of using unsafe
function pointer casts.

It also adds two missing structures to struct nfsd4_op.u to facilitate
this.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Except for a lot of unnecessary casts this typedef only has one user,
so remove the casts and expand it in struct nfsd4_operation.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Pass union nfsd4_op_u to the op_set_currentstateid callbacks instead of
using unsafe function pointer casts.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Given the args union in struct nfsd4_op a name, and pass it to the
op_set_currentstateid callbacks instead of using unsafe function
pointer casts.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Drop the resp argument as it can trivially be derived from the rqstp
argument.  With that all functions now have the same prototype, and we
can remove the unsafe casting to kxdrproc_t.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Drop the argp argument as it can trivially be derived from the rqstp
argument.  With that all functions now have the same prototype, and we
can remove the unsafe casting to kxdrproc_t.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Drop the p and resp arguments as they are always NULL or can trivially
be derived from the rqstp argument.  With that all functions now have the
same prototype, and we can remove the unsafe casting to kxdrproc_t.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Drop the argp and resp arguments as they can trivially be derived from
the rqstp argument.  With that all functions now have the same prototype,
and we can remove the unsafe casting to svc_procfunc as well as the
svc_procfunc typedef itself.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Signed-off-by: NChristoph Hellwig <hch@lst.de>

Signed-off-by: NChristoph Hellwig <hch@lst.de>

Signed-off-by: NChristoph Hellwig <hch@lst.de>

struct rpc_procinfo contains function pointers, and marking it as
constant avoids it being able to be used as an attach vector for
code injections.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NTrond Myklebust <trond.myklebust@primarydata.com>

p_count is the only writeable memeber of struct rpc_procinfo, which is
a good candidate to be const-ified as it contains function pointers.

This patch moves it into out out struct rpc_procinfo, and into a
separate writable array that is pointed to by struct rpc_version and
indexed by p_statidx.
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Declare the p_decode callbacks with the proper prototype instead of
casting to kxdrdproc_t and losing all type safety.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJeff Layton <jlayton@redhat.com>

Declare the p_encode callbacks with the proper prototype instead of
casting to kxdreproc_t and losing all type safety.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJeff Layton <jlayton@redhat.com>

Factoring ctime into the nfsv4 change attribute gives us better
properties than just i_version alone.

Eventually we'll likely also expose this (as opposed to raw i_version)
to userspace, at which point we'll want to move it to a common helper,
called from either userspace or individual filesystems.  For now, nfsd
is the only user.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>