Commit 859f8b26 authored Sep 12, 2023 by Eric Dumazet Committed by David S. Miller Sep 15, 2023

ipv6: lockless IPV6_FLOWINFO_SEND implementation



np->sndflow reads are racy.

Use one bit ftom atomic inet->inet_flags instead,
IPV6_FLOWINFO_SEND setsockopt() can be lockless.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 6b724bc4

include/linux/ipv6.h

+1 −2

Original line number	Diff line number	Diff line
		@@ -243,8 +243,7 @@ struct ipv6_pinfo {
		} rxopt;

		/* sockopt flags */
		__u8 sndflow:1,
		srcprefs:3; /* 001: prefer temporary address
		__u8 srcprefs:3; /* 001: prefer temporary address
		* 010: prefer public address
		* 100: prefer care-of address
		*/

include/net/inet_sock.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -277,6 +277,7 @@ enum {
		INET_FLAGS_RECVERR6 = 26,
		INET_FLAGS_REPFLOW = 27,
		INET_FLAGS_RTALERT_ISOLATE = 28,
		INET_FLAGS_SNDFLOW = 29,
		};

		/* cmsg flags for inet */

net/dccp/ipv6.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -844,7 +844,7 @@ static int dccp_v6_connect(struct sock sk, struct sockaddr uaddr,

		memset(&fl6, 0, sizeof(fl6));

		if (np->sndflow) {
		if (inet6_test_bit(SNDFLOW, sk)) {
		fl6.flowlabel = usin->sin6_flowinfo & IPV6_FLOWINFO_MASK;
		IP6_ECN_flow_init(fl6.flowlabel);
		if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {

net/ipv4/ping.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -899,7 +899,6 @@ int ping_recvmsg(struct sock sk, struct msghdr msg, size_t len, int flags,

		#if IS_ENABLED(CONFIG_IPV6)
		} else if (family == AF_INET6) {
		struct ipv6_pinfo *np = inet6_sk(sk);
		struct ipv6hdr *ip6 = ipv6_hdr(skb);
		DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);

		@@ -908,7 +907,7 @@ int ping_recvmsg(struct sock sk, struct msghdr msg, size_t len, int flags,
		sin6->sin6_port = 0;
		sin6->sin6_addr = ip6->saddr;
		sin6->sin6_flowinfo = 0;
		if (np->sndflow)
		if (inet6_test_bit(SNDFLOW, sk))
		sin6->sin6_flowinfo = ip6_flowinfo(ip6);
		sin6->sin6_scope_id =
		ipv6_iface_scope_id(&sin6->sin6_addr,

net/ipv6/af_inet6.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -537,7 +537,7 @@ int inet6_getname(struct socket sock, struct sockaddr uaddr,
		}
		sin->sin6_port = inet->inet_dport;
		sin->sin6_addr = sk->sk_v6_daddr;
		if (np->sndflow)
		if (inet6_test_bit(SNDFLOW, sk))
		sin->sin6_flowinfo = np->flow_label;
		BPF_CGROUP_RUN_SA_PROG(sk, (struct sockaddr *)sin,
		CGROUP_INET6_GETPEERNAME);