linux.git/include/crypto/if_alg.h, branch v7.3-rc2

crypto: af_alg - Replace 'bool privileged' with flags

2026-08-10T08:34:21+00:00

It isn't obvious what false/true mean at the definition sites, so let's
replace it with flags instead.  Also flip the polarity to make the
default zero-initialized value be the secure (privileged-only) value.

Signed-off-by: Eric Biggers 
Signed-off-by: Herbert Xu

crypto: af_alg - clean up kernel-doc warnings

2026-07-30T07:36:41+00:00

- add missing struct member @wait, drop @completion
- convert function comments to kernel-doc format
- for af_alg_readable(), change comments from "writable" to "readable"

Warning: include/crypto/if_alg.h:161 struct member 'wait' not described
 in 'af_alg_ctx'
Warning: include/crypto/if_alg.h:161 Excess struct member 'completion'
 description in 'af_alg_ctx'
Warning: include/crypto/if_alg.h:187 This comment starts with '/**', but
 isn't a kernel-doc comment.
 * Size of available buffer for sending data from user space to kernel.
Warning: include/crypto/if_alg.h:202 This comment starts with '/**', but
 isn't a kernel-doc comment.
 * Can the send buffer still be written to?
Warning: include/crypto/if_alg.h:213 This comment starts with '/**', but
 isn't a kernel-doc comment.
 * Size of available buffer used by kernel for the RX user space operation.
Warning: include/crypto/if_alg.h:228 This comment starts with '/**', but
 isn't a kernel-doc comment.
 * Can the RX buffer still be written to?

Signed-off-by: Randy Dunlap 
Signed-off-by: Herbert Xu

crypto: af_alg - Add af_alg_restrict sysctl, defaulting to 1

2026-07-05T05:27:15+00:00

AF_ALG is a frequent source of vulnerabilities and a maintenance
nightmare.  It exposes far more functionality to userspace than ever
should have been exposed, especially to unprivileged processes.  Recent
exploits have targeted kernel internal implementation details like
"authencesn" that have zero use case for userspace access.

Fortunately, AF_ALG is rarely used in practice, as userspace crypto
libraries exist.  And when it is used, only some functionality is known
to be used, and many users are known to hold capabilities already.
iwd for example requires CAP_NET_ADMIN and has a known algorithm list
(https://lore.kernel.org/linux-crypto/bcbbef00-5881-421b-8892-7be6c04b832d@gmail.com/).

Thus, let's restrict the set of allowed algorithms by default, depending
on the capabilities held.

Add a sysctl /proc/sys/crypto/af_alg_restrict with meaning:

    0: unrestricted
    1: limited functionality
    2: completely disabled

Set the default value to 1, which enables an algorithm allowlist for
unprivileged processes and a slightly longer allowlist for privileged
processes.

Note that the list may be tweaked in the future.  However, the common
use cases such as iwd and bluez are taken into account already.  I've
tested that iwd still works with the default value of 1.

Signed-off-by: Eric Biggers 
Signed-off-by: Herbert Xu

crypto: af_alg - Drop support for off-CPU cryptography

2026-05-29T06:05:30+00:00

AF_ALG is deprecated and exposed to unprivileged userspace.  Only
use the least buggy algorithm implementations: the pure software ones.

This removes one of the main advantages of AF_ALG, which is the
ability to use it with off-CPU accelerators.  However, using off-CPU
accelerators has huge overheads, both in performance and attack surface.
I have yet to see real-world, performance-critical workloads where using
an accelerator via AF_ALG is actually a win over doing cryptography in
userspace.

If using an off-CPU accelerator really does turn out to be a win, a new
API should be developed that is actually a good fit for it.

Signed-off-by: Demi Marie Obenour 
Signed-off-by: Herbert Xu

net: Remove support for AIO on sockets

2026-05-29T06:05:30+00:00

The only user of msg->msg_iocb was AF_ALG, but that's deprecated.
It can be removed entirely at the cost of only supporting synchronous
operations.  This doesn't break userspace, which will silently block
(for a bounded amount of time) in io_submit instead of operating
asynchronously.

This also makes struct msghdr smaller, helping every other caller of
sendmsg().

Signed-off-by: Demi Marie Obenour 
Acked-by: Jakub Kicinski 
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: af_alg - Fix incorrect boolean values in af_alg_ctx

2025-09-24T21:43:32+00:00

Commit 1b34cbbf4f01 ("crypto: af_alg - Disallow concurrent writes in
af_alg_sendmsg") changed some fields from bool to 1-bit bitfields of
type u32.

However, some assignments to these fields, specifically 'more' and
'merge', assign values greater than 1.  These relied on C's implicit
conversion to bool, such that zero becomes false and nonzero becomes
true.

With a 1-bit bitfields of type u32 instead, mod 2 of the value is taken
instead, resulting in 0 being assigned in some cases when 1 was intended.

Fix this by restoring the bool type.

Fixes: 1b34cbbf4f01 ("crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: Linus Torvalds

crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg

2025-09-18T09:24:59+00:00

Issuing two writes to the same af_alg socket is bogus as the
data will be interleaved in an unpredictable fashion.  Furthermore,
concurrent writes may create inconsistencies in the internal
socket state.

Disallow this by adding a new ctx->write field that indiciates
exclusive ownership for writing.

Fixes: 8ff590903d5 ("crypto: algif_skcipher - User-space interface for skcipher operations")
Reported-by: Muhammad Alifa Ramdhan 
Reported-by: Bing-Jhong Billy Jheng 
Signed-off-by: Herbert Xu

net: change proto and proto_ops accept type

2024-05-14T00:19:09+00:00

Rather than pass in flags, error pointer, and whether this is a kernel
invocation or not, add a struct proto_accept_arg struct as the argument.
This then holds all of these arguments, and prepares accept for being
able to pass back more information.

No functional changes in this patch.

Acked-by: Jakub Kicinski 
Signed-off-by: Jens Axboe

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