BMC/Intel-BMC/linux.git/net/ipv4/inet_connection_sock.c, branch dev-5.7

net: inet_csk: Fix so_reuseport bind-address cache in tb->fast*

2020-05-19T22:36:21+00:00

The commit 637bc8bbe6c0 ("inet: reset tb->fastreuseport when adding a reuseport sk") added a bind-address cache in tb->fast*. The tb->fast* caches the address of a sk which has successfully been binded with SO_REUSEPORT ON. The idea is to avoid the expensive conflict search in inet_csk_bind_conflict(). There is an issue with wildcard matching where sk_reuseport_match() should have returned false but it is currently returning true. It ends up hiding bind conflict. For example, bind("[::1]:443"); /* without SO_REUSEPORT. Succeed. */ bind("[::2]:443"); /* with SO_REUSEPORT. Succeed. */ bind("[::]:443"); /* with SO_REUSEPORT. Still Succeed where it shouldn't */ The last bind("[::]:443") with SO_REUSEPORT on should have failed because it should have a conflict with the very first bind("[::1]:443") which has SO_REUSEPORT off. However, the address "[::2]" is cached in tb->fast* in the second bind. In the last bind, the sk_reuseport_match() returns true because the binding sk's wildcard addr "[::]" matches with the "[::2]" cached in tb->fast*. The correct bind conflict is reported by removing the second bind such that tb->fast* cache is not involved and forces the bind("[::]:443") to go through the inet_csk_bind_conflict(): bind("[::1]:443"); /* without SO_REUSEPORT. Succeed. */ bind("[::]:443"); /* with SO_REUSEPORT. -EADDRINUSE */ The expected behavior for sk_reuseport_match() is, it should only allow the "cached" tb->fast* address to be used as a wildcard match but not the address of the binding sk. To do that, the current "bool match_wildcard" arg is split into "bool match_sk1_wildcard" and "bool match_sk2_wildcard". This change only affects the sk_reuseport_match() which is only used by inet_csk (e.g. TCP). The other use cases are calling inet_rcv_saddr_equal() and this patch makes it pass the same "match_wildcard" arg twice to the "ipv[46]_rcv_saddr_equal(..., match_wildcard, match_wildcard)". Cc: Josef Bacik Fixes: 637bc8bbe6c0 ("inet: reset tb->fastreuseport when adding a reuseport sk") Signed-off-by: Martin KaFai Lau Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-03-13T05:34:48+00:00

Minor overlapping changes, nothing serious. Signed-off-by: David S. Miller

tcp: Forbid to bind more than one sockets haveing SO_REUSEADDR and SO_REUSEPORT per EUID.

2020-03-12T19:08:09+00:00

If there is no TCP_LISTEN socket on a ephemeral port, we can bind multiple sockets having SO_REUSEADDR to the same port. Then if all sockets bound to the port have also SO_REUSEPORT enabled and have the same EUID, all of them can be listened. This is not safe. Let's say, an application has root privilege and binds sockets to an ephemeral port with both of SO_REUSEADDR and SO_REUSEPORT. When none of sockets is not listened yet, a malicious user can use sudo, exhaust ephemeral ports, and bind sockets to the same ephemeral port, so he or she can call listen and steal the port. To prevent this issue, we must not bind more than one sockets that have the same EUID and both of SO_REUSEADDR and SO_REUSEPORT. On the other hand, if the sockets have different EUIDs, the issue above does not occur. After sockets with different EUIDs are bound to the same port and one of them is listened, no more socket can be listened. This is because the condition below is evaluated true and listen() for the second socket fails. } else if (!reuseport_ok || !reuseport || !sk2->sk_reuseport || rcu_access_pointer(sk->sk_reuseport_cb) || (sk2->sk_state != TCP_TIME_WAIT && !uid_eq(uid, sock_i_uid(sk2)))) { if (inet_rcv_saddr_equal(sk, sk2, true)) break; } Therefore, on the same port, we cannot do listen() for multiple sockets with different EUIDs and any other listen syscalls fail, so the problem does not happen. In this case, we can still call connect() for other sockets that cannot be listened, so we have to succeed to call bind() in order to fully utilize 4-tuples. Summarizing the above, we should be able to bind only one socket having SO_REUSEADDR and SO_REUSEPORT per EUID. Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller

tcp: bind(0) remove the SO_REUSEADDR restriction when ephemeral ports are exhausted.

2020-03-12T19:08:09+00:00

Commit aacd9289af8b82f5fb01bcdd53d0e3406d1333c7 ("tcp: bind() use stronger condition for bind_conflict") introduced a restriction to forbid to bind SO_REUSEADDR enabled sockets to the same (addr, port) tuple in order to assign ports dispersedly so that we can connect to the same remote host. The change results in accelerating port depletion so that we fail to bind sockets to the same local port even if we want to connect to the different remote hosts. You can reproduce this issue by following instructions below. 1. # sysctl -w net.ipv4.ip_local_port_range="32768 32768" 2. set SO_REUSEADDR to two sockets. 3. bind two sockets to (localhost, 0) and the latter fails. Therefore, when ephemeral ports are exhausted, bind(0) should fallback to the legacy behaviour to enable the SO_REUSEADDR option and make it possible to connect to different remote (addr, port) tuples. This patch allows us to bind SO_REUSEADDR enabled sockets to the same (addr, port) only when net.ipv4.ip_autobind_reuse is set 1 and all ephemeral ports are exhausted. This also allows connect() and listen() to share ports in the following way and may break some applications. So the ip_autobind_reuse is 0 by default and disables the feature. 1. setsockopt(sk1, SO_REUSEADDR) 2. setsockopt(sk2, SO_REUSEADDR) 3. bind(sk1, saddr, 0) 4. bind(sk2, saddr, 0) 5. connect(sk1, daddr) 6. listen(sk2) If it is set 1, we can fully utilize the 4-tuples, but we should use IP_BIND_ADDRESS_NO_PORT for bind()+connect() as possible. The notable thing is that if all sockets bound to the same port have both SO_REUSEADDR and SO_REUSEPORT enabled, we can bind sockets to an ephemeral port and also do listen(). Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller

tcp: Remove unnecessary conditions in inet_csk_bind_conflict().

2020-03-12T19:08:09+00:00

When we get an ephemeral port, the relax is false, so the SO_REUSEADDR conditions may be evaluated twice. We do not need to check the conditions again. Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller

net: memcg: fix lockdep splat in inet_csk_accept()

2020-03-12T06:57:33+00:00

Locking newsk while still holding the listener lock triggered a lockdep splat [1] We can simply move the memcg code after we release the listener lock, as this can also help if multiple threads are sharing a common listener. Also fix a typo while reading socket sk_rmem_alloc. [1] WARNING: possible recursive locking detected 5.6.0-rc3-syzkaller #0 Not tainted -------------------------------------------- syz-executor598/9524 is trying to acquire lock: ffff88808b5b8b90 (sk_lock-AF_INET6){+.+.}, at: lock_sock include/net/sock.h:1541 [inline] ffff88808b5b8b90 (sk_lock-AF_INET6){+.+.}, at: inet_csk_accept+0x69f/0xd30 net/ipv4/inet_connection_sock.c:492 but task is already holding lock: ffff88808b5b9590 (sk_lock-AF_INET6){+.+.}, at: lock_sock include/net/sock.h:1541 [inline] ffff88808b5b9590 (sk_lock-AF_INET6){+.+.}, at: inet_csk_accept+0x8d/0xd30 net/ipv4/inet_connection_sock.c:445 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(sk_lock-AF_INET6); lock(sk_lock-AF_INET6); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by syz-executor598/9524: #0: ffff88808b5b9590 (sk_lock-AF_INET6){+.+.}, at: lock_sock include/net/sock.h:1541 [inline] #0: ffff88808b5b9590 (sk_lock-AF_INET6){+.+.}, at: inet_csk_accept+0x8d/0xd30 net/ipv4/inet_connection_sock.c:445 stack backtrace: CPU: 0 PID: 9524 Comm: syz-executor598 Not tainted 5.6.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:2370 [inline] check_deadlock kernel/locking/lockdep.c:2411 [inline] validate_chain kernel/locking/lockdep.c:2954 [inline] __lock_acquire.cold+0x114/0x288 kernel/locking/lockdep.c:3954 lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484 lock_sock_nested+0xc5/0x110 net/core/sock.c:2947 lock_sock include/net/sock.h:1541 [inline] inet_csk_accept+0x69f/0xd30 net/ipv4/inet_connection_sock.c:492 inet_accept+0xe9/0x7c0 net/ipv4/af_inet.c:734 __sys_accept4_file+0x3ac/0x5b0 net/socket.c:1758 __sys_accept4+0x53/0x90 net/socket.c:1809 __do_sys_accept4 net/socket.c:1821 [inline] __se_sys_accept4 net/socket.c:1818 [inline] __x64_sys_accept4+0x93/0xf0 net/socket.c:1818 do_syscall_64+0xf6/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4445c9 Code: e8 0c 0d 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc35b37608 EFLAGS: 00000246 ORIG_RAX: 0000000000000120 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004445c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000306777 R09: 0000000000306777 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000004053d0 R14: 0000000000000000 R15: 0000000000000000 Fixes: d752a4986532 ("net: memcg: late association of sock to memcg") Signed-off-by: Eric Dumazet Cc: Shakeel Butt Reported-by: syzbot Signed-off-by: David S. Miller

net: memcg: late association of sock to memcg

2020-03-10T22:33:05+00:00

If a TCP socket is allocated in IRQ context or cloned from unassociated (i.e. not associated to a memcg) in IRQ context then it will remain unassociated for its whole life. Almost half of the TCPs created on the system are created in IRQ context, so, memory used by such sockets will not be accounted by the memcg. This issue is more widespread in cgroup v1 where network memory accounting is opt-in but it can happen in cgroup v2 if the source socket for the cloning was created in root memcg. To fix the issue, just do the association of the sockets at the accept() time in the process context and then force charge the memory buffer already used and reserved by the socket. Signed-off-by: Shakeel Butt Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

tcp/ipv4: remove AF_INET_FAMILY

2020-01-21T11:03:51+00:00

After commit 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table") the macro isn't used anymore. remove it. Signed-off-by: Alex Shi Cc: "David S. Miller" Cc: Alexey Kuznetsov Cc: Hideaki YOSHIFUJI Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller

tcp, ulp: Add clone operation to tcp_ulp_ops

2020-01-10T02:41:41+00:00

If ULP is used on a listening socket, icsk_ulp_ops and icsk_ulp_data are copied when the listener is cloned. Sometimes the clone is immediately deleted, which will invoke the release op on the clone and likely corrupt the listening socket's icsk_ulp_data. The clone operation is invoked immediately after the clone is copied and gives the ULP type an opportunity to set up the clone socket and its icsk_ulp_data. The MPTCP ULP clone will silently fallback to plain TCP on allocation failure, so 'clone()' does not need to return an error code. v6 -> v7: - move and rename ulp clone helper to make it inline-friendly v5 -> v6: - clarified MPTCP clone usage in commit message Signed-off-by: Mat Martineau Signed-off-by: David S. Miller

net: add bool confirm_neigh parameter for dst_ops.update_pmtu

2019-12-25T06:28:54+00:00

The MTU update code is supposed to be invoked in response to real networking events that update the PMTU. In IPv6 PMTU update function __ip6_rt_update_pmtu() we called dst_confirm_neigh() to update neighbor confirmed time. But for tunnel code, it will call pmtu before xmit, like: - tnl_update_pmtu() - skb_dst_update_pmtu() - ip6_rt_update_pmtu() - __ip6_rt_update_pmtu() - dst_confirm_neigh() If the tunnel remote dst mac address changed and we still do the neigh confirm, we will not be able to update neigh cache and ping6 remote will failed. So for this ip_tunnel_xmit() case, _EVEN_ if the MTU is changed, we should not be invoking dst_confirm_neigh() as we have no evidence of successful two-way communication at this point. On the other hand it is also important to keep the neigh reachability fresh for TCP flows, so we cannot remove this dst_confirm_neigh() call. To fix the issue, we have to add a new bool parameter for dst_ops.update_pmtu to choose whether we should do neigh update or not. I will add the parameter in this patch and set all the callers to true to comply with the previous way, and fix the tunnel code one by one on later patches. v5: No change. v4: No change. v3: Do not remove dst_confirm_neigh, but add a new bool parameter in dst_ops.update_pmtu to control whether we should do neighbor confirm. Also split the big patch to small ones for each area. v2: Remove dst_confirm_neigh in __ip6_rt_update_pmtu. Suggested-by: David Miller Reviewed-by: Guillaume Nault Acked-by: David Ahern Signed-off-by: Hangbin Liu Signed-off-by: David S. Miller