SUNRPC: fix some memleaks in gssx_dec_option_array

The creds and oa->data need to be freed in the error-handling paths after
their allocation. So this patch add these deallocations in the
corresponding paths.

Fixes: 1d658336b05f ("SUNRPC: Add RPC based upcall mechanism for RPCGSS auth")
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

SUNRPC: Remove XDRBUF_SPARSE_PAGES flag in gss_proxy upcall

There's no need to defer allocation of pages for the receive buffer.

- This upcall is quite infrequent
- gssp_alloc_receive_pages() can allocate the pages with GFP_KERNEL,
unlike the transport
- gssp_alloc_receive_pages() knows exactly how many pages are needed

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Olga Kornievskaia <kolga@netapp.com>

SUNRPC: Remove XDRBUF_SPARSE_PAGES flag in gss_proxy upcall

There's no need to defer allocation of pages for the receive buffer.

- This upcall is quite infrequent
- gssp_alloc_receive_pages() can allocate the pages with GFP_KERNEL,
unlike the transport
- gssp_alloc_receive_pages() knows exactly how many pages are needed

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Olga Kornievskaia <aglo@umich.edu>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

SUNRPC: Add xdr_set_scratch_page() and xdr_reset_scratch_buffer()

Clean up: De-duplicate some frequently-used code.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

SUNRPC: Add SPDX IDs to some net/sunrpc/auth_gss/ files

Files under net/sunrpc/auth_gss/ do not yet have SPDX ID tags.
This directory is somewhat complicated because most of these files
have license boilerplate that is not strictly GPL 2.0.

In this patch I add ID tags where there is an obvious match. The
less recognizable licenses are still under research.

For reference, SPDX IDs added in this patch correspond to the
following license text:

GPL-2.0 https://spdx.org/licenses/GPL-2.0.html
GPL-2.0+ https://spdx.org/licenses/GPL-2.0+.html
BSD-3-Clause https://spdx.org/licenses/BSD-3-Clause.html

Cc: Simo Sorce <simo@redhat.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

SUNRPC: Add a label for RPC calls that require allocation on receive

If the RPC call relies on the receive call allocating pages as buffers,
then let's label it so that we
a) Don't leak memory by allocating pages for requests that do not expect
this behaviour
b) Can optimise for the common case where calls do not require allocation.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

kernel: make groups_sort calling a responsibility group_info allocators

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 <thiago.becker@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Acked-by: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sunrpc/auth_gss: fix decoder callback prototypes

Declare the p_decode callbacks with the proper prototype instead of
casting to kxdrdproc_t and losing all type safety.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>

sunrpc/auth_gss: nfsd: fix encoder callback prototypes

Declare the p_encode callbacks with the proper prototype instead of
casting to kxdreproc_t and losing all type safety.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>

sunrpc/auth_gss: fix decoder callback prototypes

Declare the p_decode callbacks with the proper prototype instead of
casting to kxdrdproc_t and losing all type safety.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>

sunrpc/auth_gss: nfsd: fix encoder callback prototypes

Declare the p_encode callbacks with the proper prototype instead of
casting to kxdreproc_t and losing all type safety.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>

svcrpc: fix oops in absence of krb5 module

Olga Kornievskaia says: "I ran into this oops in the nfsd (below)
(4.10-rc3 kernel). To trigger this I had a client (unsuccessfully) try
to mount the server with krb5 where the server doesn't have the
rpcsec_gss_krb5 module built."

The problem is that rsci.cred is copied from a svc_cred structure that
gss_proxy didn't properly initialize. Fix that.

[120408.542387] general protection fault: 0000 [#1] SMP
...
[120408.565724] CPU: 0 PID: 3601 Comm: nfsd Not tainted 4.10.0-rc3+ #16
[120408.567037] Hardware name: VMware, Inc. VMware Virtual =
Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015
[120408.569225] task: ffff8800776f95c0 task.stack: ffffc90003d58000
[120408.570483] RIP: 0010:gss_mech_put+0xb/0x20 [auth_rpcgss]
...
[120408.584946] ? rsc_free+0x55/0x90 [auth_rpcgss]
[120408.585901] gss_proxy_save_rsc+0xb2/0x2a0 [auth_rpcgss]
[120408.587017] svcauth_gss_proxy_init+0x3cc/0x520 [auth_rpcgss]
[120408.588257] ? __enqueue_entity+0x6c/0x70
[120408.589101] svcauth_gss_accept+0x391/0xb90 [auth_rpcgss]
[120408.590212] ? try_to_wake_up+0x4a/0x360
[120408.591036] ? wake_up_process+0x15/0x20
[120408.592093] ? svc_xprt_do_enqueue+0x12e/0x2d0 [sunrpc]
[120408.593177] svc_authenticate+0xe1/0x100 [sunrpc]
[120408.594168] svc_process_common+0x203/0x710 [sunrpc]
[120408.595220] svc_process+0x105/0x1c0 [sunrpc]
[120408.596278] nfsd+0xe9/0x160 [nfsd]
[120408.597060] kthread+0x101/0x140
[120408.597734] ? nfsd_destroy+0x60/0x60 [nfsd]
[120408.598626] ? kthread_park+0x90/0x90
[120408.599448] ret_from_fork+0x22/0x30

Fixes: 1d658336b05f "SUNRPC: Add RPC based upcall mechanism for RPCGSS auth"
Cc: stable@vger.kernel.org
Cc: Simo Sorce <simo@redhat.com>
Reported-by: Olga Kornievskaia <kolga@netapp.com>
Tested-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

cred: simpler, 1D supplementary groups

Current supplementary groups code can massively overallocate memory and
is implemented in a way so that access to individual gid is done via 2D
array.

If number of gids is <= 32, memory allocation is more or less tolerable
(140/148 bytes). But if it is not, code allocates full page (!)
regardless and, what's even more fun, doesn't reuse small 32-entry
array.

2D array means dependent shifts, loads and LEAs without possibility to
optimize them (gid is never known at compile time).

All of the above is unnecessary. Switch to the usual
trailing-zero-len-array scheme. Memory is allocated with
kmalloc/vmalloc() and only as much as needed. Accesses become simpler
(LEA 8(gi,idx,4) or even without displacement).

Maximum number of gids is 65536 which translates to 256KB+8 bytes. I
think kernel can handle such allocation.

On my usual desktop system with whole 9 (nine) aux groups, struct
group_info shrinks from 148 bytes to 44 bytes, yay!

Nice side effects:

- "gi->gid[i]" is shorter than "GROUP_AT(gi, i)", less typing,

- fix little mess in net/ipv4/ping.c
should have been using GROUP_AT macro but this point becomes moot,

- aux group allocation is persistent and should be accounted as such.

Link: http://lkml.kernel.org/r/20160817201927.GA2096@p183.telecom.by
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Vasily Kulikov <segoon@openwall.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

svcrpc: fix potential GSSX_ACCEPT_SEC_CONTEXT decoding failures

In an environment where the KDC is running Active Directory, the
exported composite name field returned in the context could be large
enough to span a page boundary. Attaching a scratch buffer to the
decoding xdr_stream helps deal with those cases.

The case where we saw this was actually due to behavior that's been
fixed in newer gss-proxy versions, but we're fixing it here too.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

svcrpc: handle some gssproxy encoding errors

Reported-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

rpc: fix huge kmalloc's in gss-proxy

The reply to a gssproxy can include up to NGROUPS_MAX gid's, which will
take up more than a page. We therefore need to allocate an array of
pages to hold the reply instead of trying to allocate a single huge
buffer.

Tested-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

rpc: comment on linux_cred encoding, treat all as unsigned

The encoding of linux creds is a bit confusing.

Also: I think in practice it doesn't really matter whether we treat any
of these things as signed or unsigned, but unsigned seems more
straightforward: uid_t/gid_t are unsigned and it simplifies the ngroups
overflow check.

Tested-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

rpc: clean up decoding of gssproxy linux creds

We can use the normal coding infrastructure here.

Two minor behavior changes:

- we're assuming no wasted space at the end of the linux cred.
That seems to match gss-proxy's behavior, and I can't see why
it would need to do differently in the future.

- NGROUPS_MAX check added: note groups_alloc doesn't do this,
this is the caller's responsibility.

Tested-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

svcrpc: fix gss-proxy xdr decoding oops

Uninitialized stack data was being used as the destination for memcpy's.

Longer term we'll just delete some of this code; all we're doing is
skipping over xdr that we don't care about.

Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

SUNRPC: fix decoding of optional gss-proxy xdr fields

The current code works, but sort of by accident: it obviously didn't
intend the error return to be interpreted as "true".

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

SUNRPC: Refactor gssx_dec_option_array() to kill uninitialized warning

net/sunrpc/auth_gss/gss_rpc_xdr.c: In function ‘gssx_dec_option_array’:
net/sunrpc/auth_gss/gss_rpc_xdr.c:258: warning: ‘creds’ may be used uninitialized in this function

Return early if count is zero, to make it clearer to the compiler (and the
casual reviewer) that no more processing is done.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

svcrpc: fix gss-proxy to respect user namespaces

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

SUNRPC: Add RPC based upcall mechanism for RPCGSS auth

This patch implements a sunrpc client to use the services of the gssproxy
userspace daemon.

In particular it allows to perform calls in user space using an RPC
call instead of custom hand-coded upcall/downcall messages.

Currently only accept_sec_context is implemented as that is all is needed for
the server case.

File server modules like NFS and CIFS can use full gssapi services this way,
once init_sec_context is also implemented.

For the NFS server case this code allow to lift the limit of max 2k krb5
tickets. This limit is prevents legitimate kerberos deployments from using krb5
authentication with the Linux NFS server as they have normally ticket that are
many kilobytes large.

It will also allow to lift the limitation on the size of the credential set
(uid,gid,gids) passed down from user space for users that have very many groups
associated. Currently the downcall mechanism used by rpc.svcgssd is limited
to around 2k secondary groups of the 65k allowed by kernel structures.

Signed-off-by: Simo Sorce <simo@redhat.com>
[bfields: containerization, concurrent upcalls, misc. fixes and cleanup]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>