KEYS: Differentiate uses of rcu_dereference_key() and user_key_payload()

rcu_dereference_key() and user_key_payload() are currently being used in
two different, incompatible ways:

(1) As a wrapper

KEYS: Differentiate uses of rcu_dereference_key() and user_key_payload()

rcu_dereference_key() and user_key_payload() are currently being used in
two different, incompatible ways:

(1) As a wrapper to rcu_dereference() - when only the RCU read lock used
to protect the key.

(2) As a wrapper to rcu_dereference_protected() - when the key semaphor is
used to protect the key and the may be being modified.

Fix this by splitting both of the key wrappers to produce:

(1) RCU accessors for keys when caller has the key semaphore locked:

dereference_key_locked()
user_key_payload_locked()

(2) RCU accessors for keys when caller holds the RCU read lock:

dereference_key_rcu()
user_key_payload_rcu()

This should fix following warning in the NFS idmapper

===============================
[ INFO: suspicious RCU usage. ]
4.10.0 #1 Tainted: G W
-------------------------------
./include/keys/user-type.h:53 suspicious rcu_dereference_protected() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 0
1 lock held by mount.nfs/5987:
#0: (rcu_read_lock){......}, at: [<d000000002527abc>] nfs_idmap_get_key+0x15c/0x420 [nfsv4]
stack backtrace:
CPU: 1 PID: 5987 Comm: mount.nfs Tainted: G W 4.10.0 #1
Call Trace:
dump_stack+0xe8/0x154 (unreliable)
lockdep_rcu_suspicious+0x140/0x190
nfs_idmap_get_key+0x380/0x420 [nfsv4]
nfs_map_name_to_uid+0x2a0/0x3b0 [nfsv4]
decode_getfattr_attrs+0xfac/0x16b0 [nfsv4]
decode_getfattr_generic.constprop.106+0xbc/0x150 [nfsv4]
nfs4_xdr_dec_lookup_root+0xac/0xb0 [nfsv4]
rpcauth_unwrap_resp+0xe8/0x140 [sunrpc]
call_decode+0x29c/0x910 [sunrpc]
__rpc_execute+0x140/0x8f0 [sunrpc]
rpc_run_task+0x170/0x200 [sunrpc]
nfs4_call_sync_sequence+0x68/0xa0 [nfsv4]
_nfs4_lookup_root.isra.44+0xd0/0xf0 [nfsv4]
nfs4_lookup_root+0xe0/0x350 [nfsv4]
nfs4_lookup_root_sec+0x70/0xa0 [nfsv4]
nfs4_find_root_sec+0xc4/0x100 [nfsv4]
nfs4_proc_get_rootfh+0x5c/0xf0 [nfsv4]
nfs4_get_rootfh+0x6c/0x190 [nfsv4]
nfs4_server_common_setup+0xc4/0x260 [nfsv4]
nfs4_create_server+0x278/0x3c0 [nfsv4]
nfs4_remote_mount+0x50/0xb0 [nfsv4]
mount_fs+0x74/0x210
vfs_kern_mount+0x78/0x220
nfs_do_root_mount+0xb0/0x140 [nfsv4]
nfs4_try_mount+0x60/0x100 [nfsv4]
nfs_fs_mount+0x5ec/0xda0 [nfs]
mount_fs+0x74/0x210
vfs_kern_mount+0x78/0x220
do_mount+0x254/0xf70
SyS_mount+0x94/0x100
system_call+0x38/0xe0

Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

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Merge branch 'next' into for-linus

Prepare input updates for 4.10 merge window.

Merge tag 'v4.9-rc3' into xtensa-for-next

Linux 4.9-rc3

Merge branch 'topic/error' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator into regulator-fixed

Merge branch 'drm-tda998x-mali' into drm-tda998x-devel

Merge tag 'v4.8' into next

Sync up with mainline to bring in I2C host notify changes and other
updates.

Merge tag 'irqchip-4.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/core

Merge the first drop of irqchip updates for 4.9 from Marc Zyngier:

- ACPI IORT core code
-

Merge tag 'irqchip-4.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/core

Merge the first drop of irqchip updates for 4.9 from Marc Zyngier:

- ACPI IORT core code
- IORT support for the GICv3 ITS
- A few of GIC cleanups

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Merge remote-tracking branch 'airlied/drm-next' into drm-intel-next-queued

Backmerge because too many conflicts, and also we need to get at the
latest struct fence patches from Gustavo. Requested by

Merge remote-tracking branch 'airlied/drm-next' into drm-intel-next-queued

Backmerge because too many conflicts, and also we need to get at the
latest struct fence patches from Gustavo. Requested by Chris Wilson.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

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Merge branch 'linus' into locking/urgent, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

Pull crypto updates from Herbert Xu:
"Here is the crypto update for 4.8:

API:
- first part of skcipher

Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

Pull crypto updates from Herbert Xu:
"Here is the crypto update for 4.8:

API:
- first part of skcipher low-level conversions
- add KPP (Key-agreement Protocol Primitives) interface.

Algorithms:
- fix IPsec/cryptd reordering issues that affects aesni
- RSA no longer does explicit leading zero removal
- add SHA3
- add DH
- add ECDH
- improve DRBG performance by not doing CTR by hand

Drivers:
- add x86 AVX2 multibuffer SHA256/512
- add POWER8 optimised crc32c
- add xts support to vmx
- add DH support to qat
- add RSA support to caam
- add Layerscape support to caam
- add SEC1 AEAD support to talitos
- improve performance by chaining requests in marvell/cesa
- add support for Araneus Alea I USB RNG
- add support for Broadcom BCM5301 RNG
- add support for Amlogic Meson RNG
- add support Broadcom NSP SoC RNG"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (180 commits)
crypto: vmx - Fix aes_p8_xts_decrypt build failure
crypto: vmx - Ignore generated files
crypto: vmx - Adding support for XTS
crypto: vmx - Adding asm subroutines for XTS
crypto: skcipher - add comment for skcipher_alg->base
crypto: testmgr - Print akcipher algorithm name
crypto: marvell - Fix wrong flag used for GFP in mv_cesa_dma_add_iv_op
crypto: nx - off by one bug in nx_of_update_msc()
crypto: rsa-pkcs1pad - fix rsa-pkcs1pad request struct
crypto: scatterwalk - Inline start/map/done
crypto: scatterwalk - Remove unnecessary BUG in scatterwalk_start
crypto: scatterwalk - Remove unnecessary advance in scatterwalk_pagedone
crypto: scatterwalk - Fix test in scatterwalk_done
crypto: api - Optimise away crypto_yield when hard preemption is on
crypto: scatterwalk - add no-copy support to copychunks
crypto: scatterwalk - Remove scatterwalk_bytes_sglen
crypto: omap - Stop using crypto scatterwalk_bytes_sglen
crypto: skcipher - Remove top-level givcipher interface
crypto: user - Remove crypto_lookup_skcipher call
crypto: cts - Convert to skcipher
...

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lib/digsig: digsig_verify_rsa(): return -EINVAL if modulo length is zero

Currently, if digsig_verify_rsa() detects that the modulo's length is zero,
i.e. mlen == 0, it returns -ENOMEM which doesn't

lib/digsig: digsig_verify_rsa(): return -EINVAL if modulo length is zero

Currently, if digsig_verify_rsa() detects that the modulo's length is zero,
i.e. mlen == 0, it returns -ENOMEM which doesn't really fit here.

Make digsig_verify_rsa() return -EINVAL upon mlen == 0.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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lib/mpi: mpi_read_from_buffer(): return error code

mpi_read_from_buffer() reads a MPI from a buffer into a newly allocated
MPI instance. It expects the buffer's leading two bytes to contain the
numb

lib/mpi: mpi_read_from_buffer(): return error code

mpi_read_from_buffer() reads a MPI from a buffer into a newly allocated
MPI instance. It expects the buffer's leading two bytes to contain the
number of bits, followed by the actual payload.

On failure, it returns NULL and updates the in/out argument ret_nread
somewhat inconsistently:
- If the given buffer is too short to contain the leading two bytes
encoding the number of bits or their value is unsupported, then
ret_nread will be cleared.
- If the allocation of the resulting MPI instance fails, ret_nread is left
as is.

The only user of mpi_read_from_buffer(), digsig_verify_rsa(), simply checks
for a return value of NULL and returns -ENOMEM if that happens.

While this is all of cosmetic nature only, there is another error condition
which currently isn't detectable by the caller of mpi_read_from_buffer():
if the given buffer is too small to hold the number of bits as encoded in
its first two bytes, the return value will be non-NULL and *ret_nread > 0.

In preparation of communicating this condition to the caller, let
mpi_read_from_buffer() return error values by means of the ERR_PTR()
mechanism.

Make the sole caller of mpi_read_from_buffer(), digsig_verify_rsa(),
check the return value for IS_ERR() rather than == NULL. If IS_ERR() is
true, return the associated error value rather than the fixed -ENOMEM.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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Merge remote-tracking branch 'linusw-gpio/for-next' into devm_gpiochip

Base for demv_gpiochip_add_data() and devm_gpiochip_remove().

Merge tag 'v4.4'

Linux 4.4

Orangefs: Merge tag 'v4.4-rc1' into for-next

Linux 4.4-rc1

Merge branch 'next' into for-linus

Prepare first round of input updates for 4.5 merge window.

Merge back earlier 'pm-domains' material for v4.5.

Merge branch 'linus' into x86/cleanups

Pull in upstream changes so we can apply depending patches.

Merge branch 'linus' into x86/apic

Pull in update changes so we can apply conflicting patches

Merge branches 'acpi-pci' and 'pm-pci'

* acpi-pci:
x86/PCI/ACPI: Fix regression caused by commit 4d6b4e69a245

* pm-pci:
PCI / PM: Tune down retryable runtime suspend error messages

Merge tag 'v4.4-rc3' into next

Merge with Linux 4.4-rc3 to bring in helpers for multiu-driver modules.

Merge tag 'asoc-fix-v4.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Fixes for v4.4

Quite a large batch of fixes have come in since the merge window, ma

Merge tag 'asoc-fix-v4.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Fixes for v4.4

Quite a large batch of fixes have come in since the merge window, mainly
driver specific ones but there's a couple of core ones:

- A fix for DAPM resume on active streams to ensure everything ends up
cleanly in the right state.
- Reset the DAPM cache when freeing widgets to fix a crash on driver
remove and reload.

The PM functions for nau8825 are new code which fix crashes on resume.

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Merge tag 'v4.4-rc1' into HEAD

Linux 4.4-rc1

Merge tag 'v4.4-rc2' into drm-intel-next-queued

Linux 4.4-rc2

Backmerge to get at

commit 1b0e3a049efe471c399674fd954500ce97438d30
Author: Imre Deak <imre.deak@intel.com>
Date: Thu Nov 5 23:04:11

Merge tag 'v4.4-rc2' into drm-intel-next-queued

Linux 4.4-rc2

Backmerge to get at

commit 1b0e3a049efe471c399674fd954500ce97438d30
Author: Imre Deak <imre.deak@intel.com>
Date: Thu Nov 5 23:04:11 2015 +0200

drm/i915/skl: disable display side power well support for now

so that we can proplery re-eanble skl power wells in -next.

Conflicts are just adjacent lines changed, except for intel_fbdev.c
where we need to interleave the changs. Nothing nefarious.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

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Merge tag 'v4.4-rc1' into patchwork

Linux 4.4-rc1

* tag 'v4.4-rc1': (12900 commits)
Linux 4.4-rc1
ARC: Fix silly typo in MAINTAINERS file
ARC: cpu_relax() to be compiler barrier even for UP

Merge tag 'v4.4-rc1' into patchwork

Linux 4.4-rc1

* tag 'v4.4-rc1': (12900 commits)
Linux 4.4-rc1
ARC: Fix silly typo in MAINTAINERS file
ARC: cpu_relax() to be compiler barrier even for UP
ARC: use ASL assembler mnemonic
ARC: [arcompact] Handle bus error from userspace as Interrupt not exception
ARC: remove extraneous header include
f2fs: xattr simplifications
squashfs: xattr simplifications
9p: xattr simplifications
xattr handlers: Pass handler to operations instead of flags
jffs2: Add missing capability check for listing trusted xattrs
hfsplus: Remove unused xattr handler list operations
ubifs: Remove unused security xattr handler
vfs: Fix the posix_acl_xattr_list return value
vfs: Check attribute names in posix acl xattr handers
mpt3sas: fix inline markers on non inline function declarations
dax: fix __dax_pmd_fault crash
Revert "drm/rockchip: Convert the probe function to the generic drm_of_component_probe()"
drm: Don't oops in drm_calc_timestamping_constants() if drm_vblank_init() wasn't called
ALSA: pci: depend on ZONE_DMA
...

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