From e8e36984080b55ac5e57bdb09a5b570f2fc8e963 Mon Sep 17 00:00:00 2001 From: Andrey Ignatov Date: Fri, 4 Jan 2019 01:07:07 -0800 Subject: bpf: Fix [::] -> [::1] rewrite in sys_sendmsg sys_sendmsg has supported unspecified destination IPv6 (wildcard) for unconnected UDP sockets since 876c7f41. When [::] is passed by user as destination, sys_sendmsg rewrites it with [::1] to be consistent with BSD (see "BSD'ism" comment in the code). This didn't work when cgroup-bpf was enabled though since the rewrite [::] -> [::1] happened before passing control to cgroup-bpf block where fl6.daddr was updated with passed by user sockaddr_in6.sin6_addr (that might or might not be changed by BPF program). That way if user passed [::] as dst IPv6 it was first rewritten with [::1] by original code from 876c7f41, but then rewritten back with [::] by cgroup-bpf block. It happened even when BPF_CGROUP_UDP6_SENDMSG program was not present (CONFIG_CGROUP_BPF=y was enough). The fix is to apply BSD'ism after cgroup-bpf block so that [::] is replaced with [::1] no matter where it came from: passed by user to sys_sendmsg or set by BPF_CGROUP_UDP6_SENDMSG program. Fixes: 1cedee13d25a ("bpf: Hooks for sys_sendmsg") Reported-by: Nitin Rawat Signed-off-by: Andrey Ignatov Signed-off-by: Alexei Starovoitov --- net/ipv6/udp.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'net/ipv6') diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 9cbf363172bd..7c3505006f8e 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1390,10 +1390,7 @@ do_udp_sendmsg: ipc6.opt = opt; fl6.flowi6_proto = sk->sk_protocol; - if (!ipv6_addr_any(daddr)) - fl6.daddr = *daddr; - else - fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */ + fl6.daddr = *daddr; if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr)) fl6.saddr = np->saddr; fl6.fl6_sport = inet->inet_sport; @@ -1421,6 +1418,9 @@ do_udp_sendmsg: } } + if (ipv6_addr_any(&fl6.daddr)) + fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */ + final_p = fl6_update_dst(&fl6, opt, &final); if (final_p) connected = false; -- cgit v1.2.3