Описание
In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: Reject sk_msg egress redirects to non-TCP sockets
With a SOCKMAP/SOCKHASH map and an sk_msg program user can steer messages
sent from one TCP socket (s1) to actually egress from another TCP
socket (s2):
tcp_bpf_sendmsg(s1)// = sk_prot->sendmsg
tcp_bpf_send_verdict(s1)// __SK_REDIRECT case
tcp_bpf_sendmsg_redir(s2)
tcp_bpf_push_locked(s2)
tcp_bpf_push(s2)
tcp_rate_check_app_limited(s2) // expects tcp_sock
tcp_sendmsg_locked(s2) // ditto
There is a hard-coded assumption in the call-chain, that the egress
socket (s2) is a TCP socket.
However in commit 122e6c79efe1 ("sock_map: Update sock type checks for
UDP") we have enabled redirects to non-TCP sockets. This was done for the
sake of BPF sk_skb programs. There was no indention to support sk_msg
send-to-egress use case.
As a result, attempts to send-to-egress through a non-TCP socket lead to a
crash due to invalid downcast from sock to tcp_sock:
BUG: kernel NULL pointer dereference, address: 000000000000002f
...
Call Trace:
? show_regs+0x60/0x70
? __die+0x1f/0x70
? page_fault_oops+0x80/0x160
? do_user_addr_fault+0x2d7/0x800
? rcu_is_watching+0x11/0x50
? exc_page_fault+0x70/0x1c0
? asm_exc_page_fault+0x27/0x30
? tcp_tso_segs+0x14/0xa0
tcp_write_xmit+0x67/0xce0
__tcp_push_pending_frames+0x32/0xf0
tcp_push+0x107/0x140
tcp_sendmsg_locked+0x99f/0xbb0
tcp_bpf_push+0x19d/0x3a0
tcp_bpf_sendmsg_redir+0x55/0xd0
tcp_bpf_send_verdict+0x407/0x550
tcp_bpf_sendmsg+0x1a1/0x390
inet_sendmsg+0x6a/0x70
sock_sendmsg+0x9d/0xc0
? sockfd_lookup_light+0x12/0x80
__sys_sendto+0x10e/0x160
? syscall_enter_from_user_mode+0x20/0x60
? __this_cpu_preempt_check+0x13/0x20
? lockdep_hardirqs_on+0x82/0x110
__x64_sys_sendto+0x1f/0x30
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Reject selecting a non-TCP sockets as redirect target from a BPF sk_msg
program to prevent the crash. When attempted, user will receive an EACCES
error from send/sendto/sendmsg() syscall.
This Linux kernel vulnerability in the sockmap subsystem occurs when a BPF sk_msg program attempts to redirect a message's egress from a TCP socket to a non-TCP socket, such as UDP. Because the underlying kernel call-chain hardcoded the assumption that the target would always be a TCP socket, this invalid downcast leads to a NULL pointer dereference and a subsequent kernel crash. The issue is resolved in patched kernel versions by explicitly rejecting non-TCP redirect targets for sk_msg programs, safely returning an EACCES error rather than crashing the system.
Отчет
This vulnerability is rated as Low severity because exploiting it requires privileged access, specifically capabilities such as CAP_BPF or CAP_NET_ADMIN, to load and configure custom eBPF programs on the host. An attacker with sufficient privileges could trigger a system crash by redirecting traffic to an incompatible socket type via sockmap programs, resulting in a local denial of service. The flaw cannot be leveraged remotely and does not facilitate privilege escalation or data exposure.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Not affected |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Reject sk_msg egress redirects to non-TCP sockets With a SOCKMAP/SOCKHASH map and an sk_msg program user can steer messages sent from one TCP socket (s1) to actually egress from another TCP socket (s2): tcp_bpf_sendmsg(s1) // = sk_prot->sendmsg tcp_bpf_send_verdict(s1) // __SK_REDIRECT case tcp_bpf_sendmsg_redir(s2) tcp_bpf_push_locked(s2) tcp_bpf_push(s2) tcp_rate_check_app_limited(s2) // expects tcp_sock tcp_sendmsg_locked(s2) // ditto There is a hard-coded assumption in the call-chain, that the egress socket (s2) is a TCP socket. However in commit 122e6c79efe1 ("sock_map: Update sock type checks for UDP") we have enabled redirects to non-TCP sockets. This was done for the sake of BPF sk_skb programs. There was no indention to support sk_msg send-to-egress use case. As a result, attempts to send-to-egress through a non-TCP socket lead to a crash due to invalid downcast from sock to tcp_sock: BUG: k...
In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Reject sk_msg egress redirects to non-TCP sockets With a SOCKMAP/SOCKHASH map and an sk_msg program user can steer messages sent from one TCP socket (s1) to actually egress from another TCP socket (s2): tcp_bpf_sendmsg(s1) // = sk_prot->sendmsg tcp_bpf_send_verdict(s1) // __SK_REDIRECT case tcp_bpf_sendmsg_redir(s2) tcp_bpf_push_locked(s2) tcp_bpf_push(s2) tcp_rate_check_app_limited(s2) // expects tcp_sock tcp_sendmsg_locked(s2) // ditto There is a hard-coded assumption in the call-chain, that the egress socket (s2) is a TCP socket. However in commit 122e6c79efe1 ("sock_map: Update sock type checks for UDP") we have enabled redirects to non-TCP sockets. This was done for the sake of BPF sk_skb programs. There was no indention to support sk_msg send-to-egress use case. As a result, attempts to send-to-egress through a non-TCP socket lead to a crash due to invalid downcast from so
In the Linux kernel, the following vulnerability has been resolved: b ...
In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Reject sk_msg egress redirects to non-TCP sockets With a SOCKMAP/SOCKHASH map and an sk_msg program user can steer messages sent from one TCP socket (s1) to actually egress from another TCP socket (s2): tcp_bpf_sendmsg(s1) // = sk_prot->sendmsg tcp_bpf_send_verdict(s1) // __SK_REDIRECT case tcp_bpf_sendmsg_redir(s2) tcp_bpf_push_locked(s2) tcp_bpf_push(s2) tcp_rate_check_app_limited(s2) // expects tcp_sock tcp_sendmsg_locked(s2) // ditto There is a hard-coded assumption in the call-chain, that the egress socket (s2) is a TCP socket. However in commit 122e6c79efe1 ("sock_map: Update sock type checks for UDP") we have enabled redirects to non-TCP sockets. This was done for the sake of BPF sk_skb programs. There was no indention to support sk_msg send-to-egress use case. As a result, attempts to send-to-egress through a non-TCP socket lead to a crash due to invalid downcast from...
Уязвимость компонента sockmap ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании
EPSS
5.5 Medium
CVSS3