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Eric Dumazet 56667da739 net: implement lockless setsockopt(SO_PEEK_OFF) 
syzbot reported a lockdep violation [1] involving af_unix
support of SO_PEEK_OFF.

Since SO_PEEK_OFF is inherently not thread safe (it uses a per-socket
sk_peek_off field), there is really no point to enforce a pointless
thread safety in the kernel.

After this patch :

- setsockopt(SO_PEEK_OFF) no longer acquires the socket lock.

- skb_consume_udp() no longer has to acquire the socket lock.

- af_unix no longer needs a special version of sk_set_peek_off(),
  because it does not lock u->iolock anymore.

As a followup, we could replace prot->set_peek_off to be a boolean
and avoid an indirect call, since we always use sk_set_peek_off().

[1]

WARNING: possible circular locking dependency detected
6.8.0-rc4-syzkaller-00267-g0f1dd5e91e2b #0 Not tainted

syz-executor.2/30025 is trying to acquire lock:
 ffff8880765e7d80 (&u->iolock){+.+.}-{3:3}, at: unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789

but task is already holding lock:
 ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline]
 ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1060 [inline]
 ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sk_setsockopt+0xe52/0x3360 net/core/sock.c:1193

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (sk_lock-AF_UNIX){+.+.}-{0:0}:
        lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
        lock_sock_nested+0x48/0x100 net/core/sock.c:3524
        lock_sock include/net/sock.h:1691 [inline]
        __unix_dgram_recvmsg+0x1275/0x12c0 net/unix/af_unix.c:2415
        sock_recvmsg_nosec+0x18e/0x1d0 net/socket.c:1046
        ____sys_recvmsg+0x3c0/0x470 net/socket.c:2801
        ___sys_recvmsg net/socket.c:2845 [inline]
        do_recvmmsg+0x474/0xae0 net/socket.c:2939
        __sys_recvmmsg net/socket.c:3018 [inline]
        __do_sys_recvmmsg net/socket.c:3041 [inline]
        __se_sys_recvmmsg net/socket.c:3034 [inline]
        __x64_sys_recvmmsg+0x199/0x250 net/socket.c:3034
       do_syscall_64+0xf9/0x240
       entry_SYSCALL_64_after_hwframe+0x6f/0x77

-> #0 (&u->iolock){+.+.}-{3:3}:
        check_prev_add kernel/locking/lockdep.c:3134 [inline]
        check_prevs_add kernel/locking/lockdep.c:3253 [inline]
        validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869
        __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
        lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
        __mutex_lock_common kernel/locking/mutex.c:608 [inline]
        __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
        unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789
       sk_setsockopt+0x207e/0x3360
        do_sock_setsockopt+0x2fb/0x720 net/socket.c:2307
        __sys_setsockopt+0x1ad/0x250 net/socket.c:2334
        __do_sys_setsockopt net/socket.c:2343 [inline]
        __se_sys_setsockopt net/socket.c:2340 [inline]
        __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
       do_syscall_64+0xf9/0x240
       entry_SYSCALL_64_after_hwframe+0x6f/0x77

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_UNIX);
                               lock(&u->iolock);
                               lock(sk_lock-AF_UNIX);
  lock(&u->iolock);

 *** DEADLOCK ***

1 lock held by syz-executor.2/30025:
  #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline]
  #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1060 [inline]
  #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sk_setsockopt+0xe52/0x3360 net/core/sock.c:1193

stack backtrace:
CPU: 0 PID: 30025 Comm: syz-executor.2 Not tainted 6.8.0-rc4-syzkaller-00267-g0f1dd5e91e2b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call Trace:
 <TASK>
  __dump_stack lib/dump_stack.c:88 [inline]
  dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
  check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
  check_prev_add kernel/locking/lockdep.c:3134 [inline]
  check_prevs_add kernel/locking/lockdep.c:3253 [inline]
  validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869
  __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
  lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
  __mutex_lock_common kernel/locking/mutex.c:608 [inline]
  __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
  unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789
 sk_setsockopt+0x207e/0x3360
  do_sock_setsockopt+0x2fb/0x720 net/socket.c:2307
  __sys_setsockopt+0x1ad/0x250 net/socket.c:2334
  __do_sys_setsockopt net/socket.c:2343 [inline]
  __se_sys_setsockopt net/socket.c:2340 [inline]
  __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
 do_syscall_64+0xf9/0x240
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f78a1c7dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f78a0fde0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f78a1dac050 RCX: 00007f78a1c7dda9
RDX: 000000000000002a RSI: 0000000000000001 RDI: 0000000000000006
RBP: 00007f78a1cca47a R08: 0000000000000004 R09: 0000000000000000
R10: 0000000020000180 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f78a1dac050 R15: 00007ffe5cd81ae8

Fixes: 859051dd16 ("bpf: Implement cgroup sockaddr hooks for unix sockets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Daan De Meyer <daan.j.demeyer@gmail.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Cc: David Ahern <dsahern@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 		2024-02-21 11:24:20 +00:00
..
netfilter netfilter: bridge: replace physindev with physinif in nf_bridge_info 2024-01-17 12:02:49 +01:00
Kconfig net/tcp: Add TCP-AO config and structures 2023-10-27 10:35:44 +01:00
Makefile bpfilter: remove bpfilter 2024-01-04 10:23:10 -08:00
af_inet.c inet: read sk->sk_family once in inet_recv_error() 2024-02-04 16:06:53 +00:00
ah4.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00
arp.c arp: Prevent overflow in arp_req_get(). 2024-02-20 10:50:19 +01:00
bpf_tcp_ca.c Revert BPF token-related functionality 2023-12-19 08:23:03 -08:00
cipso_ipv4.c inet: move inet->is_icsk to inet->inet_flags 2023-08-16 11:09:17 +01:00
datagram.c inet: implement lockless getsockopt(IP_MULTICAST_IF) 2023-10-01 19:39:19 +01:00
devinet.c ipv4: properly combine dev_base_seq and ipv4.dev_addr_genid 2024-02-18 10:22:27 +00:00
esp4.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00
esp4_offload.c xfrm: Support GRO for IPv4 ESP in UDP encapsulation 2023-10-06 07:30:40 +02:00
fib_frontend.c
…
fib_lookup.h
…
fib_notifier.c
…
fib_rules.c fib: remove unnecessary input parameters in fib_default_rule_add 2024-01-03 16:42:48 -08:00
fib_semantics.c ipv4: fib: annotate races around nh->nh_saddr_genid and nh->nh_saddr 2023-10-18 18:11:31 -07:00
fib_trie.c Kill sched.h dependency on rcupdate.h 2023-12-27 11:50:20 -05:00
fou_bpf.c bpf: Add __bpf_kfunc_{start,end}_defs macros 2023-11-01 22:33:53 -07:00
fou_core.c
…
fou_nl.c
…
fou_nl.h
…
gre_demux.c
…
gre_offload.c
…
icmp.c xfrm: pass struct net to xfrm_decode_session wrappers 2023-10-06 08:31:53 +02:00
igmp.c ipv4: igmp: fix refcnt uaf issue when receiving igmp query packet 2023-11-24 15:25:56 +00:00
inet_connection_sock.c tcp: make sure init the accept_queue's spinlocks once 2024-01-19 21:13:25 -08:00
inet_diag.c tcp: Link sk and twsk to tb2->owners using skc_bind_node. 2023-12-22 22:15:35 +00:00
inet_fragment.c
…
inet_hashtables.c dccp/tcp: Unhash sk from ehash for tb2 alloc failure after check_estalblished(). 2024-02-16 09:41:54 +00:00
inet_timewait_sock.c tcp: Link sk and twsk to tb2->owners using skc_bind_node. 2023-12-22 22:15:35 +00:00
inetpeer.c
…
ip_forward.c net: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check 2023-10-13 09:58:45 -07:00
ip_fragment.c networking: Update to register_net_sysctl_sz 2023-08-15 15:26:18 -07:00
ip_gre.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00
ip_input.c ipv4: ignore dst hint for multipath routes 2023-09-01 08:11:51 +01:00
ip_options.c
…
ip_output.c net-timestamp: make sk_tskey more predictable in error path 2024-02-15 12:04:04 +01:00
ip_sockglue.c ipmr: fix kernel panic when forwarding mcast packets 2024-01-26 21:05:26 -08:00
ip_tunnel.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00
ip_tunnel_core.c tunnels: fix out of bounds access when building IPv6 PMTU error 2024-02-03 12:43:19 +00:00
ip_vti.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00
ipcomp.c
…
ipconfig.c
…
ipip.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00
ipmr.c ipmr: fix kernel panic when forwarding mcast packets 2024-01-26 21:05:26 -08:00
ipmr_base.c
…
metrics.c
…
netfilter.c xfrm: pass struct net to xfrm_decode_session wrappers 2023-10-06 08:31:53 +02:00
netlink.c
…
nexthop.c nexthop: Do not increment dump sentinel at the end of the dump 2023-08-15 18:54:53 -07:00
ping.c bpf-next-for-netdev 2023-10-16 21:05:33 -07:00
proc.c net/tcp: Ignore specific ICMPs for TCP-AO connections 2023-10-27 10:35:45 +01:00
protocol.c
…
raw.c ipmr: fix kernel panic when forwarding mcast packets 2024-01-26 21:05:26 -08:00
raw_diag.c net: fill in MODULE_DESCRIPTION()s for SOCK_DIAG modules 2023-11-19 20:09:13 +00:00
route.c ipv4: Correct/silence an endian warning in __ip_do_redirect 2023-11-21 12:55:22 +01:00
syncookies.c tcp: Factorise cookie-dependent fields initialisation in cookie_v[46]_check() 2023-11-29 20:16:38 -08:00
sysctl_net_ipv4.c Use READ/WRITE_ONCE() for IP local_port_range. 2023-12-08 10:44:42 -08:00
tcp.c tcp: move tp->scaling_ratio to tcp_sock_read_txrx group 2024-02-12 09:51:26 +00:00
tcp_ao.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-12-07 17:53:17 -08:00
tcp_bbr.c net: implement lockless SO_MAX_PACING_RATE 2023-10-01 19:09:54 +01:00
tcp_bic.c
…
tcp_bpf.c tcp_bpf: properly release resources on error paths 2023-10-18 18:09:31 -07:00
tcp_cdg.c
…
tcp_cong.c
…
tcp_cubic.c
…
tcp_dctcp.c
…
tcp_dctcp.h
…
tcp_diag.c net: fill in MODULE_DESCRIPTION()s for SOCK_DIAG modules 2023-11-19 20:09:13 +00:00
tcp_fastopen.c inet: move inet->defer_connect to inet->inet_flags 2023-08-16 11:09:18 +01:00
tcp_highspeed.c
…
tcp_htcp.c
…
tcp_hybla.c
…
tcp_illinois.c
…
tcp_input.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-12-14 17:14:41 -08:00
tcp_ipv4.c tcp: Revert no longer abort SYN_SENT when receiving some ICMP 2024-01-08 19:08:51 -08:00
tcp_lp.c tcp: rename tcp_time_stamp() to tcp_time_stamp_ts() 2023-10-23 09:35:01 +01:00
tcp_metrics.c tcp_metrics: optimize tcp_metrics_flush_all() 2023-10-03 10:05:22 +02:00
tcp_minisocks.c net/tcp: Consistently align TCP-AO option in the header 2023-12-06 12:36:55 +01:00
tcp_nv.c
…
tcp_offload.c
…
tcp_output.c net: Remove acked SYN flag from packet in the transmit queue correctly 2023-12-12 15:56:02 -08:00
tcp_plb.c
…
tcp_rate.c
…
tcp_recovery.c tcp: fix excessive TLP and RACK timeouts from HZ rounding 2023-10-17 17:25:42 -07:00
tcp_scalable.c
…
tcp_sigpool.c net/tcp_sigpool: Use kref_get_unless_zero() 2024-01-01 14:42:05 +00:00
tcp_timer.c tcp: use tp->total_rto to track number of linear timeouts in SYN_SENT state 2023-11-16 23:35:12 +00:00
tcp_ulp.c
…
tcp_vegas.c
…
tcp_vegas.h
…
tcp_veno.c
…
tcp_westwood.c
…
tcp_yeah.c
…
tunnel4.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00
udp.c net: implement lockless setsockopt(SO_PEEK_OFF) 2024-02-21 11:24:20 +00:00
udp_bpf.c
…
udp_diag.c net: fill in MODULE_DESCRIPTION()s for SOCK_DIAG modules 2023-11-19 20:09:13 +00:00
udp_impl.h sock: Remove ->sendpage*() in favour of sendmsg(MSG_SPLICE_PAGES) 2023-06-24 15:50:13 -07:00
udp_offload.c udp: move udp->gro_enabled to udp->udp_flags 2023-09-14 16:16:36 +02:00
udp_tunnel_core.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00
udp_tunnel_nic.c udp_tunnel: Use flex array to simplify code 2023-10-03 11:39:34 +02:00
udp_tunnel_stub.c
…
udplite.c udplite: remove UDPLITE_BIT 2023-09-14 16:16:36 +02:00
xfrm4_input.c xfrm Fix use after free in __xfrm6_udp_encap_rcv. 2023-10-23 07:10:39 +02:00
xfrm4_output.c
…
xfrm4_policy.c sysctl-6.6-rc1 2023-08-29 17:39:15 -07:00
xfrm4_protocol.c
…
xfrm4_state.c
…
xfrm4_tunnel.c net: fill in MODULE_DESCRIPTION()s for ipv4 modules 2024-02-09 14:12:02 -08:00