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Message-ID: <20230921133021.1995349-2-edumazet@google.com>
Date: Thu, 21 Sep 2023 13:30:14 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 1/8] inet: implement lockless IP_MULTICAST_TTL
inet->mc_ttl can be read locklessly.
Implement proper lockless reads and writes to inet->mc_ttl
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/ipv4/ip_output.c | 2 +-
net/ipv4/ip_sockglue.c | 31 ++++++++++++++++---------------
net/netfilter/ipvs/ip_vs_sync.c | 2 +-
3 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 4ab877cf6d35f229761986d5c6a17eb2a3ad4043..adad16f1e872ce20941a087b3965fdb040868d4e 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1430,7 +1430,7 @@ struct sk_buff *__ip_make_skb(struct sock *sk,
if (cork->ttl != 0)
ttl = cork->ttl;
else if (rt->rt_type == RTN_MULTICAST)
- ttl = inet->mc_ttl;
+ ttl = READ_ONCE(inet->mc_ttl);
else
ttl = ip_select_ttl(inet, &rt->dst);
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index cce9cb25f3b31cd57fa883ae0dedb6829d8da2fa..4ad3003378ae6b186513000264f77b54a7babe6d 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -1039,6 +1039,17 @@ int do_ip_setsockopt(struct sock *sk, int level, int optname,
WRITE_ONCE(inet->min_ttl, val);
return 0;
+ case IP_MULTICAST_TTL:
+ if (sk->sk_type == SOCK_STREAM)
+ return -EINVAL;
+ if (optlen < 1)
+ return -EINVAL;
+ if (val == -1)
+ val = 1;
+ if (val < 0 || val > 255)
+ return -EINVAL;
+ WRITE_ONCE(inet->mc_ttl, val);
+ return 0;
}
err = 0;
@@ -1101,17 +1112,6 @@ int do_ip_setsockopt(struct sock *sk, int level, int optname,
goto e_inval;
inet->pmtudisc = val;
break;
- case IP_MULTICAST_TTL:
- if (sk->sk_type == SOCK_STREAM)
- goto e_inval;
- if (optlen < 1)
- goto e_inval;
- if (val == -1)
- val = 1;
- if (val < 0 || val > 255)
- goto e_inval;
- inet->mc_ttl = val;
- break;
case IP_UNICAST_IF:
{
struct net_device *dev = NULL;
@@ -1592,6 +1592,9 @@ int do_ip_getsockopt(struct sock *sk, int level, int optname,
case IP_MINTTL:
val = READ_ONCE(inet->min_ttl);
goto copyval;
+ case IP_MULTICAST_TTL:
+ val = READ_ONCE(inet->mc_ttl);
+ goto copyval;
}
if (needs_rtnl)
@@ -1649,9 +1652,6 @@ int do_ip_getsockopt(struct sock *sk, int level, int optname,
}
break;
}
- case IP_MULTICAST_TTL:
- val = inet->mc_ttl;
- break;
case IP_UNICAST_IF:
val = (__force int)htonl((__u32) inet->uc_index);
break;
@@ -1718,7 +1718,8 @@ int do_ip_getsockopt(struct sock *sk, int level, int optname,
put_cmsg(&msg, SOL_IP, IP_PKTINFO, sizeof(info), &info);
}
if (inet_test_bit(TTL, sk)) {
- int hlim = inet->mc_ttl;
+ int hlim = READ_ONCE(inet->mc_ttl);
+
put_cmsg(&msg, SOL_IP, IP_TTL, sizeof(hlim), &hlim);
}
if (inet_test_bit(TOS, sk)) {
diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
index 5820a8156c4701bb163f569d735c389d7a8e3820..3eed1670224888acf639cff06537ddf2505461bb 100644
--- a/net/netfilter/ipvs/ip_vs_sync.c
+++ b/net/netfilter/ipvs/ip_vs_sync.c
@@ -1316,7 +1316,7 @@ static void set_mcast_ttl(struct sock *sk, u_char ttl)
/* setsockopt(sock, SOL_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); */
lock_sock(sk);
- inet->mc_ttl = ttl;
+ WRITE_ONCE(inet->mc_ttl, ttl);
#ifdef CONFIG_IP_VS_IPV6
if (sk->sk_family == AF_INET6) {
struct ipv6_pinfo *np = inet6_sk(sk);
--
2.42.0.459.ge4e396fd5e-goog
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