bpf: tcp: Fix type confusion in bpf_tcp_sock().

bpf_tcp_sock() only checks if sk->sk_protocol is IPPROTO_TCP,
but RAW socket can bypass it:

  socket(AF_INET, SOCK_RAW, IPPROTO_TCP)

Calling bpf_setsockopt() in SOCKOPT prog triggers out-of-bounds
access to another slab object. [0]

Let's use sk_is_tcp().

[0]:
BUG: KASAN: slab-out-of-bounds in sol_tcp_sockopt (net/core/filter.c:5519)
Read of size 8 at addr ffff88801083d760 by task test_progs/1259

CPU: 1 UID: 0 PID: 1259 Comm: test_progs Tainted: G           OE       7.0.0-11175-gb5c111f4967b #1 PREEMPT(full)
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
 print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)
 kasan_report (mm/kasan/report.c:595)
 sol_tcp_sockopt (net/core/filter.c:5519)
 __bpf_getsockopt (net/core/filter.c:5633)
 bpf_sk_getsockopt (net/core/filter.c:5654)
 bpf_prog_629ba00a1601e9f2__setsockopt+0x86/0x22c
 __cgroup_bpf_run_filter_setsockopt (./include/linux/bpf.h:1402 ./include/linux/filter.h:722 ./include/linux/filter.h:729 kernel/bpf/cgroup.c:81 kernel/bpf/cgroup.c:2026)
 do_sock_setsockopt (net/socket.c:2363)
 __x64_sys_setsockopt (net/socket.c:2406)
 do_syscall_64 (arch/x86/entry/syscall_64.c:63)
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
RIP: 0033:0x7f85f82fe7de
Code: 55 48 63 c9 48 63 ff 45 89 c9 48 89 e5 48 83 ec 08 6a 2c e8 34 69 f7 ff c9 c3 66 90 f3 0f 1e fa 49 89 ca b8 36 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 0a c3 66 0f 1f 84 00 00 00 00 00 48 8b 15 e1
RSP: 002b:00007ffe59dcecd8 EFLAGS: 00000202 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f85f82fe7de
RDX: 000000000000001c RSI: 0000000000000006 RDI: 000000000000000d
RBP: 00007ffe59dcef20 R08: 000000000000003c R09: 0000000000000000
R10: 00007ffe59dcef00 R11: 0000000000000202 R12: 00007ffe59dcf268
R13: 0000000000000003 R14: 00007f85f9da5000 R15: 000055b2f3201400
 </TASK>

The buggy address belongs to the object at ffff88801083d280
 which belongs to the cache RAW of size 1792
The buggy address is located 1248 bytes inside of
 allocated 1792-byte region [ffff88801083d280, ffff88801083d980)

Fixes: 655a51e536c0 ("bpf: Add struct bpf_tcp_sock and BPF_FUNC_tcp_sock")
Reported-by: Damiano Melotti <melotti@google.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://patch.msgid.link/20260504210610.180150-2-kuniyu@google.com

diff --git a/net/core/filter.c b/net/core/filter.c
index bc96c18df4e03b842d2d8cd807e6770a494a07df..cd88633f8dc148a5c37b94f686924a74c08ce0ce 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -7475,7 +7475,7 @@ u32 bpf_tcp_sock_convert_ctx_access(enum bpf_access_type type,
 
 BPF_CALL_1(bpf_tcp_sock, struct sock *, sk)
 {
-       if (sk_fullsock(sk) && sk->sk_protocol == IPPROTO_TCP)
+       if (sk_fullsock(sk) && sk_is_tcp(sk))
                return (unsigned long)sk;
 
        return (unsigned long)NULL;