linux-stable.git/crypto/algif_skcipher.c, branch linux-rolling-stable

crypto: algif_skcipher - force synchronous processing

2026-07-24T14:18:58+00:00

The AIO/async path in skcipher_recvmsg() passes the socket-wide ctx->iv
directly into the skcipher request. After io_submit() the socket lock is
dropped and the request is processed asynchronously by a worker (e.g.
cryptd), which dereferences ctx->iv only later.

A concurrent sendmsg(ALG_SET_IV) on the same socket can overwrite ctx->iv
inside this window, so the in-flight request runs under an
attacker-controlled IV. For CTR and other stream modes this causes
IV/keystream reuse and allows an unprivileged user to recover the
plaintext of a concurrent operation.

Snapshotting ctx->iv into per-request storage for the async path is not
sufficient here. For ciphers with statesize == 0 - which includes cbc
and ctr - skcipher_prepare_alg() installs skcipher_noimport()/
skcipher_noexport(), so ctx->state carries nothing and the MSG_MORE
inter-chunk IV chaining is carried solely by the in-place req->iv
writeback. A snapshot redirects that writeback into per-request memory
that af_alg_free_resources() releases on completion, so AIO + MSG_MORE
with cbc/ctr would silently produce wrong output. Writing the IV back
from the completion callback instead is not possible either: that would
require lock_sock() there, but the callback can run in softirq/atomic
context, so it must not sleep.

Make the operation synchronous instead. ctx->iv is then only ever
dereferenced under the socket lock held by recvmsg(), which removes the
race, and the req->iv writeback lands in ctx->iv as before, which keeps
MSG_MORE chaining intact for statesize == 0 ciphers. The ctx->state
import/export path is unchanged for ciphers that do have state.

This is equivalent to the upstream resolution: commit fcc77d33a34c
("net: Remove support for AIO on sockets") removed the AIO socket path
across net/ entirely, producing the same end state for this file -
algif_skcipher never processes an AIO request asynchronously. After this
patch, _skcipher_recvmsg() matches mainline's crypto/algif_skcipher.c as
it stands today, including the same now-dead -EIOCBQUEUED check. This
patch deviates from that commit deliberately: rather than removing AIO
socket support tree-wide, which would be far too invasive for stable, it
removes only the AIO branch in crypto/algif_skcipher.c. io_submit() now
completes synchronously, which is valid for the AIO interface; AF_ALG
async is rarely used in practice.

The -EIOCBQUEUED check in skcipher_recvmsg() is now dead but harmless,
and is left alone to keep the fix minimal.

Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management")
Cc: 
Reported-by: Muhammet Kaan KILINÇ 
Signed-off-by: Muhammet Kaan KILINÇ 
Signed-off-by: Sasha Levin

crypto: af_alg - limit RX SG extraction by receive buffer budget

2026-04-03T00:54:14+00:00

Make af_alg_get_rsgl() limit each RX scatterlist extraction to the
remaining receive buffer budget.

af_alg_get_rsgl() currently uses af_alg_readable() only as a gate
before extracting data into the RX scatterlist. Limit each extraction
to the remaining af_alg_rcvbuf(sk) budget so that receive-side
accounting matches the amount of data attached to the request.

If skcipher cannot obtain enough RX space for at least one chunk while
more data remains to be processed, reject the recvmsg call instead of
rounding the request length down to zero.

Fixes: e870456d8e7c8d57c059ea479b5aadbb55ff4c3a ("crypto: algif_skcipher - overhaul memory management")
Reported-by: Yifan Wu 
Reported-by: Juefei Pu 
Co-developed-by: Yuan Tan 
Signed-off-by: Yuan Tan 
Suggested-by: Xin Liu 
Signed-off-by: Douya Le 
Signed-off-by: Ren Wei 
Signed-off-by: Herbert Xu

crypto: algif_aead - Revert to operating out-of-place

2026-03-31T08:11:47+00:00

This mostly reverts commit 72548b093ee3 except for the copying of
the associated data.

There is no benefit in operating in-place in algif_aead since the
source and destination come from different mappings.  Get rid of
all the complexity added for in-place operation and just copy the
AD directly.

Fixes: 72548b093ee3 ("crypto: algif_aead - copy AAD from src to dst")
Reported-by: Taeyang Lee <0wn@theori.io>
Signed-off-by: Herbert Xu

crypto: Add missing MODULE_DESCRIPTION() macros

2024-05-31T09:34:56+00:00

Fix the 'make W=1' warnings:
WARNING: modpost: missing MODULE_DESCRIPTION() in crypto/cast_common.o
WARNING: modpost: missing MODULE_DESCRIPTION() in crypto/af_alg.o
WARNING: modpost: missing MODULE_DESCRIPTION() in crypto/algif_hash.o
WARNING: modpost: missing MODULE_DESCRIPTION() in crypto/algif_skcipher.o
WARNING: modpost: missing MODULE_DESCRIPTION() in crypto/ecc.o
WARNING: modpost: missing MODULE_DESCRIPTION() in crypto/curve25519-generic.o
WARNING: modpost: missing MODULE_DESCRIPTION() in crypto/xor.o
WARNING: modpost: missing MODULE_DESCRIPTION() in crypto/crypto_simd.o

Signed-off-by: Jeff Johnson 
Signed-off-by: Herbert Xu

crypto: algif_skcipher - Fix stream cipher chaining

2023-12-08T03:59:46+00:00

Unlike algif_aead which is always issued in one go (thus limiting
the maximum size of the request), algif_skcipher has always allowed
unlimited input data by cutting them up as necessary and feeding
the fragments to the underlying algorithm one at a time.

However, because of deficiencies in the API, this has been broken
for most stream ciphers such as arc4 or chacha.  This is because
they have an internal state in addition to the IV that must be
preserved in order to continue processing.

Fix this by using the new skcipher state API.

Signed-off-by: Herbert Xu

sock: Remove ->sendpage*() in favour of sendmsg(MSG_SPLICE_PAGES)

2023-06-24T22:50:13+00:00

Remove ->sendpage() and ->sendpage_locked().  sendmsg() with
MSG_SPLICE_PAGES should be used instead.  This allows multiple pages and
multipage folios to be passed through.

Signed-off-by: David Howells 
Acked-by: Marc Kleine-Budde  # for net/can
cc: Jens Axboe 
cc: Matthew Wilcox 
cc: linux-afs@lists.infradead.org
cc: mptcp@lists.linux.dev
cc: rds-devel@oss.oracle.com
cc: tipc-discussion@lists.sourceforge.net
cc: virtualization@lists.linux-foundation.org
Link: https://lore.kernel.org/r/20230623225513.2732256-16-dhowells@redhat.com
Signed-off-by: Jakub Kicinski

crypto: af_alg: Support MSG_SPLICE_PAGES

2023-06-08T11:42:34+00:00

Make AF_ALG sendmsg() support MSG_SPLICE_PAGES.  This causes pages to be
spliced from the source iterator.

This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.

Signed-off-by: David Howells 
cc: Herbert Xu 
cc: "David S. Miller" 
cc: Eric Dumazet 
cc: Jakub Kicinski 
cc: Paolo Abeni 
cc: Jens Axboe 
cc: Matthew Wilcox 
cc: linux-crypto@vger.kernel.org
cc: netdev@vger.kernel.org
Acked-by: Herbert Xu 
Signed-off-by: Paolo Abeni

crypto: af_alg: Use extract_iter_to_sg() to create scatterlists

2023-06-08T11:42:34+00:00

Use extract_iter_to_sg() to decant the destination iterator into a
scatterlist in af_alg_get_rsgl().  af_alg_make_sg() can then be removed.

Signed-off-by: David Howells 
cc: Herbert Xu 
cc: "David S. Miller" 
cc: Eric Dumazet 
cc: Jakub Kicinski 
cc: Paolo Abeni 
cc: Jens Axboe 
cc: Matthew Wilcox 
cc: linux-crypto@vger.kernel.org
cc: netdev@vger.kernel.org
Acked-by: Herbert Xu 
Signed-off-by: Paolo Abeni

crypto: algif_skcipher - EBUSY on aio should be an error

2020-08-21T04:45:26+00:00

I removed the MAY_BACKLOG flag on the aio path a while ago but
the error check still incorrectly interpreted EBUSY as success.
This may cause the submitter to wait for a request that will never
complete.

Fixes: dad419970637 ("crypto: algif_skcipher - Do not set...")
Signed-off-by: Herbert Xu

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

2020-08-14T20:09:15+00:00

Pull crypto fix from Herbert Xu:
 "This fixes a regression in af_alg"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: algif_aead - fix uninitialized ctx->init