sctp_wait_for_connect() drops and re-acquires the socket lock while
waiting for the association to reach ESTABLISHED state. During this
window, another thread can peeloff the association to a new socket via
getsockopt(SCTP_SOCKOPT_PEELOFF), changing asoc->base.sk. After
re-acquiring the old socket lock, sctp_wait_for_connect() returns
success without noticing the migration — the caller then accesses
the association under the wrong lock in sctp_datamsg_from_user().
Add the same sk != asoc->base.sk check that sctp_wait_for_sndbuf()
already has, returning an error if the association was migrated while
we slept.
Fixes: 668c9beb90 ("sctp: implement assign_number for sctp_stream_interleave")
Signed-off-by: Zhenghang Xiao <kipreyyy@gmail.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20260527032411.60959-1-kipreyyy@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The SCTP_SENDALL path in sctp_sendmsg() iterates ep->asocs with
list_for_each_entry_safe(), which caches the next entry in @tmp before
the loop body runs. The body calls sctp_sendmsg_to_asoc(), which may
drop the socket lock inside sctp_wait_for_sndbuf().
While the lock is dropped, another thread can SCTP_SOCKOPT_PEELOFF the
association cached in @tmp, migrating it to a new endpoint via
sctp_sock_migrate() (list_del_init() + list_add_tail() to
newep->asocs), and optionally close the new socket which frees the
association via kfree_rcu(). The cached @tmp can also be freed by a
network ABORT for that association, processed in softirq while the
lock is dropped.
sctp_wait_for_sndbuf() revalidates @asoc (the current entry) on re-lock
via the "sk != asoc->base.sk" and "asoc->base.dead" checks, but nothing
revalidates @tmp. After a successful return, the iterator advances to
the stale @tmp, yielding either a use-after-free (if the peeled socket
was closed) or a list-walk onto the new endpoint's list head (type
confusion of &newep->asocs as a struct sctp_association *).
Both are reachable from CapEff=0; the type-confusion path gives
controlled indirect call via the outqueue.sched->init_sid pointer.
Fix by re-deriving @tmp from @asoc after sctp_sendmsg_to_asoc()
returns. @asoc is known to still be on ep->asocs at that point: the
only callers that list_del an association from ep->asocs are
sctp_association_free() (which sets asoc->base.dead) and
sctp_assoc_migrate() (which changes asoc->base.sk), and
sctp_wait_for_sndbuf() checks both under the lock before any
successful return; a tripped check propagates as err < 0 and the loop
bails before the re-derive.
The SCTP_ABORT path in sctp_sendmsg_check_sflags() returns 0 and the
loop hits 'continue' before sctp_sendmsg_to_asoc() is ever called, so
the @tmp cached by list_for_each_entry_safe() still covers the
lock-held free that ba59fb0273 ("sctp: walk the list of asoc
safely") was added for.
Fixes: 4910280503 ("sctp: add support for snd flag SCTP_SENDALL process in sendmsg")
Cc: stable@vger.kernel.org
Signed-off-by: Ben Morris <bmorris@anthropic.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20260508001455.3137-1-joycathacker@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
sk_clone() increments sockets_allocated and sets the socket refcount to 2.
SCTP performs additional accounting in sctp_clone_sock(), so the clone-time
increment must be undone to avoid double counting.
Note we cannot simply remove the SCTP-side increment, because the SCTP
destroy path in sctp_destroy_sock() only decrements sockets_allocated when
sp->ep is set, which may not be true for all failure paths in
sctp_clone_sock().
Fixes: 16942cf4d3 ("sctp: Use sk_clone() in sctp_accept().")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/af8d66f928dec3e9fcbee8d4a85b7d5a6b86f515.1776460180.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
sctp_getsockopt_peer_auth_chunks() checks that the caller's optval
buffer is large enough for the peer AUTH chunk list with
if (len < num_chunks)
return -EINVAL;
but then writes num_chunks bytes to p->gauth_chunks, which lives
at offset offsetof(struct sctp_authchunks, gauth_chunks) == 8
inside optval. The check is missing the sizeof(struct
sctp_authchunks) = 8-byte header. When the caller supplies
len == num_chunks (for any num_chunks > 0) the test passes but
copy_to_user() writes sizeof(struct sctp_authchunks) = 8 bytes
past the declared buffer.
The sibling function sctp_getsockopt_local_auth_chunks() at the
next line already has the correct check:
if (len < sizeof(struct sctp_authchunks) + num_chunks)
return -EINVAL;
Align the peer variant with its sibling.
Reproducer confirms on v7.0-13-generic: an unprivileged userspace
caller that opens a loopback SCTP association with AUTH enabled,
queries num_chunks with a short optval, then issues the real
getsockopt with len == num_chunks and sentinel bytes painted past
the buffer observes those sentinel bytes overwritten with the
peer's AUTH chunk type. The bytes written are under the peer's
control but land in the caller's own userspace; this is not a
kernel memory corruption, but it is a kernel-side contract
violation that can silently corrupt adjacent userspace data.
Fixes: 65b07e5d0d ("[SCTP]: API updates to suport SCTP-AUTH extensions.")
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20260416031903.1447072-1-michael.bommarito@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
Convert struct proto pre_connect(), connect(), bind(), and bind_add()
callback function prototypes from struct sockaddr to struct sockaddr_unsized.
This does not change per-implementation use of sockaddr for passing around
an arbitrarily sized sockaddr struct. Those will be addressed in future
patches.
Additionally removes the no longer referenced struct sockaddr from
include/net/inet_common.h.
No binary changes expected.
Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20251104002617.2752303-5-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Update all struct proto_ops connect() callback function prototypes from
"struct sockaddr *" to "struct sockaddr_unsized *" to avoid lying to the
compiler about object sizes. Calls into struct proto handlers gain casts
that will be removed in the struct proto conversion patch.
No binary changes expected.
Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20251104002617.2752303-3-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
sctp_do_peeloff() calls sock_create() to allocate and initialise
struct sock, inet_sock, and sctp_sock, but later sctp_copy_sock()
and sctp_sock_migrate() overwrite most fields.
What sctp_do_peeloff() does is more like accept().
Let's use sock_create_lite() and sctp_clone_sock().
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20251023231751.4168390-8-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
sctp_accept() calls sctp_v[46]_create_accept_sk() to allocate a new
socket and calls sctp_sock_migrate() to copy fields from the parent
socket to the new socket.
sctp_v4_create_accept_sk() allocates sk by sk_alloc(), initialises
it by sock_init_data(), and copy a bunch of fields from the parent
socekt by sctp_copy_sock().
sctp_sock_migrate() calls sctp_copy_descendant() to copy most fields
in sctp_sock from the parent socket by memcpy().
These can be simply replaced by sk_clone().
Let's consolidate sctp_v[46]_create_accept_sk() to sctp_clone_sock()
with sk_clone().
We will reuse sctp_clone_sock() for sctp_do_peeloff() and then remove
sctp_copy_descendant().
Note that sock_reset_flag(newsk, SOCK_ZAPPED) is not copied to
sctp_clone_sock() as sctp does not use SOCK_ZAPPED at all.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20251023231751.4168390-6-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
sctp_accept() calls sctp_v[46]_create_accept_sk() to allocate a new
socket and calls sctp_sock_migrate() to copy fields from the parent
socket to the new socket.
sctp_v[46]_create_accept_sk() calls sctp_init_sock() to initialise
sctp_sock, but most fields are overwritten by sctp_copy_descendant()
called from sctp_sock_migrate().
Things done in sctp_init_sock() but not in sctp_sock_migrate() are
the following:
1. Copy sk->sk_gso
2. Copy sk->sk_destruct (sctp_v6_init_sock())
3. Allocate sctp_sock.ep
4. Initialise sctp_sock.pd_lobby
5. Count sk_sockets_allocated_inc(), sock_prot_inuse_add(),
and SCTP_DBG_OBJCNT_INC()
Let's do these in sctp_copy_sock() and sctp_sock_migrate() and avoid
calling sk->sk_prot->init() in sctp_v[46]_create_accept_sk().
Note that sk->sk_destruct is already copied in sctp_copy_sock().
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20251023231751.4168390-4-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
sctp_sock_migrate() is called from 2 places.
1) sctp_accept() calls sp->pf->create_accept_sk() before
sctp_sock_migrate(), and sp->pf->create_accept_sk() calls
sctp_copy_sock().
2) sctp_do_peeloff() also calls sctp_copy_sock() before
sctp_sock_migrate().
sctp_copy_sock() copies sk_sndbuf and sk_rcvbuf from the
parent socket.
Let's not copy the two fields in sctp_sock_migrate().
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20251023231751.4168390-3-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
SCTP_DBG_OBJCNT_INC() is called only when sctp_init_sock()
returns 0 after successfully allocating sctp_sk(sk)->ep.
OTOH, SCTP_DBG_OBJCNT_DEC() is called in sctp_close().
The code seems to expect that the socket is always exposed
to userspace once SCTP_DBG_OBJCNT_INC() is incremented, but
there is a path where the assumption is not true.
In sctp_accept(), sctp_sock_migrate() could fail after
sctp_init_sock().
Then, sk_common_release() does not call inet_release() nor
sctp_close(). Instead, it calls sk->sk_prot->destroy().
Let's move SCTP_DBG_OBJCNT_DEC() from sctp_close() to
sctp_destroy_sock().
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20251023231751.4168390-2-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 <lucien.xin@gmail.com>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20250818205426.30222-5-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 <lucien.xin@gmail.com>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20250818205426.30222-4-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Followup of commit 285975dd67 ("net: annotate data-races around
sk->sk_{rcv|snd}timeo").
Remove lock_sock()/release_sock() from ksmbd_tcp_rcv_timeout()
and add READ_ONCE()/WRITE_ONCE() where it is needed.
Also SO_RCVTIMEO_OLD and SO_RCVTIMEO_NEW can call sock_set_timeout()
without holding the socket lock.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250620155536.335520-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Followup of commit 285975dd67 ("net: annotate data-races around
sk->sk_{rcv|snd}timeo").
Remove lock_sock()/release_sock() from sock_set_sndtimeo(),
and add READ_ONCE()/WRITE_ONCE() where it is needed.
Also SO_SNDTIMEO_OLD and SO_SNDTIMEO_NEW can call sock_set_timeout()
without holding the socket lock.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250620155536.335520-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Difference between sock_i_uid() and sk_uid() is that
after sock_orphan(), sock_i_uid() returns GLOBAL_ROOT_UID
while sk_uid() returns the last cached sk->sk_uid value.
None of sock_i_uid() callers care about this.
Use sk_uid() which is much faster and inlined.
Note that diag/dump users are calling sock_i_ino() and
can not see the full benefit yet.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Reviewed-by: Maciej Żenczykowski <maze@google.com>
Link: https://patch.msgid.link/20250620133001.4090592-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Function __sctp_write_space() doesn't set poll key, which leads to
ep_poll_callback() waking up all waiters, not only these waiting
for the socket being writable. Set the key properly using
wake_up_interruptible_poll(), which is preferred over the sync
variant, as writers are not woken up before at least half of the
queue is available. Also, TCP does the same.
Signed-off-by: Petr Malat <oss@malat.biz>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20250516081727.1361451-1-oss@malat.biz
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
RFS can exhibit lower performance for workloads using short-lived
flows and a small set of 4-tuple.
This is often the case for load-testers, using a pair of hosts,
if the server has a single listener port.
Typical use case :
Server : tcp_crr -T128 -F1000 -6 -U -l30 -R 14250
Client : tcp_crr -T128 -F1000 -6 -U -l30 -c -H server | grep local_throughput
This is because RFS global hash table contains stale information,
when the same RSS key is recycled for another socket and another cpu.
Make sure to undo the changes and go back to initial state when
a flow is disconnected.
Performance of the above test is increased by 22 %,
going from 372604 transactions per second to 457773.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Octavian Purdila <tavip@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20250515100354.3339920-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 47faa1e4c5 ("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: df132eff46 ("sctp: clear the transport of some out_chunk_list chunks in sctp_assoc_rm_peer")
Suggested-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Ricardo Cañuelo Navarro <rcn@igalia.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
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 <pabeni@redhat.com>
