kernel/linux.git/include/net/sctp/structs.h, branch v6.18.22

sctp: Convert cookie authentication to use HMAC-SHA256

2025-08-20T02:36:26+00:00

Convert SCTP cookies to use HMAC-SHA256, instead of the previous choice of the legacy algorithms HMAC-MD5 and HMAC-SHA1. Simplify and optimize the code by using the HMAC-SHA256 library instead of crypto_shash, and by preparing the HMAC key when it is generated instead of per-operation. This doesn't break compatibility, since the cookie format is an implementation detail, not part of the SCTP protocol itself. Note that the cookie size doesn't change either. The HMAC field was already 32 bytes, even though previously at most 20 bytes were actually compared. 32 bytes exactly fits an untruncated HMAC-SHA256 value. So, although we could safely truncate the MAC to something slightly shorter, for now just keep the cookie size the same. I also considered SipHash, but that would generate only 8-byte MACs. An 8-byte MAC *might* suffice here. However, there's quite a lot of information in the SCTP cookies: more than in TCP SYN cookies. So absent an analysis that occasional forgeries of all that information is okay in SCTP, I errored on the side of caution. Remove HMAC-MD5 and HMAC-SHA1 as options, since the new HMAC-SHA256 option is just better. It's faster as well as more secure. For example, benchmarking on x86_64, cookie authentication is now nearly 3x as fast as the previous default choice and implementation of HMAC-MD5. Also just make the kernel always support cookie authentication if SCTP is supported at all, rather than making it optional in the build. (It was sort of optional before, but it didn't really work properly. E.g., a kernel with CONFIG_SCTP_COOKIE_HMAC_MD5=n still supported HMAC-MD5 cookie authentication if CONFIG_CRYPTO_HMAC and CONFIG_CRYPTO_MD5 happened to be enabled in the kconfig for other reasons.) Acked-by: Xin Long Signed-off-by: Eric Biggers Link: https://patch.msgid.link/20250818205426.30222-5-ebiggers@kernel.org Signed-off-by: Jakub Kicinski

sctp: Use HMAC-SHA1 and HMAC-SHA256 library for chunk authentication

2025-08-20T02:36:25+00:00

For SCTP chunk authentication, use the HMAC-SHA1 and HMAC-SHA256 library functions instead of crypto_shash. This is simpler and faster. There's no longer any need to pre-allocate 'crypto_shash' objects; the SCTP code now simply calls into the HMAC code directly. As part of this, make SCTP always support both HMAC-SHA1 and HMAC-SHA256. Previously, it only guaranteed support for HMAC-SHA1. However, HMAC-SHA256 tended to be supported too anyway, as it was supported if CONFIG_CRYPTO_SHA256 was enabled elsewhere in the kconfig. Acked-by: Xin Long Signed-off-by: Eric Biggers Link: https://patch.msgid.link/20250818205426.30222-4-ebiggers@kernel.org Signed-off-by: Jakub Kicinski

sctp: Replace sockaddr with sockaddr_inet in sctp_addr union

2025-07-25T22:29:58+00:00

As part of the removal of the variably-sized sockaddr for kernel internals, replace struct sockaddr with sockaddr_inet in the sctp_addr union. No binary changes; the union size remains unchanged due to sockaddr_inet matching the size of sockaddr_in6. Signed-off-by: Kees Cook Link: https://patch.msgid.link/20250722171836.1078436-3-kees@kernel.org Signed-off-by: Jakub Kicinski

sctp: Remove unused sctp_assoc_del_peer and sctp_chunk_iif

2025-05-05T23:51:12+00:00

sctp_assoc_del_peer() last use was removed in 2015 by commit 73e6742027f5 ("sctp: Do not try to search for the transport twice") which now uses rm_peer instead of del_peer. sctp_chunk_iif() last use was removed in 2016 by commit 1f45f78f8e51 ("sctp: allow GSO frags to access the chunk too") Remove them. Signed-off-by: Dr. David Alan Gilbert Acked-by: Xin Long Link: https://patch.msgid.link/20250501233815.99832-1-linux@treblig.org Signed-off-by: Jakub Kicinski

sctp: detect and prevent references to a freed transport in sendmsg

2025-04-08T09:34:06+00:00

sctp_sendmsg() re-uses associations and transports when possible by doing a lookup based on the socket endpoint and the message destination address, and then sctp_sendmsg_to_asoc() sets the selected transport in all the message chunks to be sent. There's a possible race condition if another thread triggers the removal of that selected transport, for instance, by explicitly unbinding an address with setsockopt(SCTP_SOCKOPT_BINDX_REM), after the chunks have been set up and before the message is sent. This can happen if the send buffer is full, during the period when the sender thread temporarily releases the socket lock in sctp_wait_for_sndbuf(). This causes the access to the transport data in sctp_outq_select_transport(), when the association outqueue is flushed, to result in a use-after-free read. This change avoids this scenario by having sctp_transport_free() signal the freeing of the transport, tagging it as "dead". In order to do this, the patch restores the "dead" bit in struct sctp_transport, which was removed in commit 47faa1e4c50e ("sctp: remove the dead field of sctp_transport"). Then, in the scenario where the sender thread has released the socket lock in sctp_wait_for_sndbuf(), the bit is checked again after re-acquiring the socket lock to detect the deletion. This is done while holding a reference to the transport to prevent it from being freed in the process. If the transport was deleted while the socket lock was relinquished, sctp_sendmsg_to_asoc() will return -EAGAIN to let userspace retry the send. The bug was found by a private syzbot instance (see the error report [1] and the C reproducer that triggers it [2]). Link: https://people.igalia.com/rcn/kernel_logs/20250402__KASAN_slab-use-after-free_Read_in_sctp_outq_select_transport.txt [1] Link: https://people.igalia.com/rcn/kernel_logs/20250402__KASAN_slab-use-after-free_Read_in_sctp_outq_select_transport__repro.c [2] Cc: stable@vger.kernel.org Fixes: df132eff4638 ("sctp: clear the transport of some out_chunk_list chunks in sctp_assoc_rm_peer") Suggested-by: Xin Long Signed-off-by: Ricardo Cañuelo Navarro Acked-by: Xin Long Link: https://patch.msgid.link/20250404-kasan_slab-use-after-free_read_in_sctp_outq_select_transport__20250404-v1-1-5ce4a0b78ef2@igalia.com Signed-off-by: Paolo Abeni

sctp: Correct spelling in headers

2024-08-26T16:37:23+00:00

Correct spelling in sctp.h and structs.h. As reported by codespell. Cc: Marcelo Ricardo Leitner Signed-off-by: Simon Horman Acked-by: Xin Long Link: https://patch.msgid.link/20240822-net-spell-v1-10-3a98971ce2d2@kernel.org Signed-off-by: Jakub Kicinski

sctp: preserve const qualifier in sctp_sk()

2024-02-05T11:08:06+00:00

We can change sctp_sk() to propagate its argument const qualifier, thanks to container_of_const(). Signed-off-by: Eric Dumazet Cc: Marcelo Ricardo Leitner Cc: Xin Long Acked-by: Xin Long Signed-off-by: David S. Miller

sctp: Remove unused function declarations

2023-08-03T01:42:03+00:00

These declarations are never implemented since beginning of git history. Signed-off-by: Yue Haibing Reviewed-by: Simon Horman Acked-by: Xin Long Link: https://lore.kernel.org/r/20230731141030.32772-1-yuehaibing@huawei.com Signed-off-by: Jakub Kicinski

sctp: delete the nested flexible array peer_init

2023-04-21T07:19:30+00:00

This patch deletes the flexible-array peer_init[] from the structure sctp_cookie to avoid some sparse warnings: # make C=2 CF="-Wflexible-array-nested" M=./net/sctp/ net/sctp/sm_make_chunk.c: note: in included file (through include/net/sctp/sctp.h): ./include/net/sctp/structs.h:1588:28: warning: nested flexible array ./include/net/sctp/structs.h:343:28: warning: nested flexible array Signed-off-by: Xin Long Signed-off-by: David S. Miller

sctp: delete the obsolete code for the host name address param

2023-04-17T07:28:20+00:00

In the latest RFC9260, the Host Name Address param has been deprecated. For INIT chunk: Note 3: An INIT chunk MUST NOT contain the Host Name Address parameter. The receiver of an INIT chunk containing a Host Name Address parameter MUST send an ABORT chunk and MAY include an "Unresolvable Address" error cause. For Supported Address Types: The value indicating the Host Name Address parameter MUST NOT be used when sending this parameter and MUST be ignored when receiving this parameter. Currently Linux SCTP doesn't really support Host Name Address param, but only saves some flag and print debug info, which actually won't even be triggered due to the verification in sctp_verify_param(). This patch is to delete those dead code. Signed-off-by: Xin Long Signed-off-by: David S. Miller