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Date: Mon, 18 Sep 2023 14:23:21 +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: netdev@...r.kernel.org, David Ahern <dsahern@...nel.org>, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] ipv6: lockless IPV6_ADDR_PREFERENCES implementation
We have data-races while reading np->srcprefs
Switch the field to a plain byte, add READ_ONCE()
and WRITE_ONCE() annotations where needed,
and IPV6_ADDR_PREFERENCES setsockopt() can now be lockless.
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
include/linux/ipv6.h | 2 +-
include/net/ip6_route.h | 5 ++---
include/net/ipv6.h | 20 +++++++-------------
net/ipv6/ip6_output.c | 2 +-
net/ipv6/ipv6_sockglue.c | 19 ++++++++++---------
net/ipv6/route.c | 2 +-
6 files changed, 22 insertions(+), 28 deletions(-)
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 09253825c99c7a94c4c8a3f176f0ceecd0b166bc..e400ff757f136e72e81277d48063551e445b4970 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -243,7 +243,7 @@ struct ipv6_pinfo {
} rxopt;
/* sockopt flags */
- __u8 srcprefs:3; /* 001: prefer temporary address
+ __u8 srcprefs; /* 001: prefer temporary address
* 010: prefer public address
* 100: prefer care-of address
*/
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index b1ea49900b4ae17cb3436f884e26f5ae3a7a761c..28b0657902615157c4cbd836cc70e0767cf49a4d 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -53,13 +53,12 @@ struct route_info {
*/
static inline int rt6_srcprefs2flags(unsigned int srcprefs)
{
- /* No need to bitmask because srcprefs have only 3 bits. */
- return srcprefs << 3;
+ return (srcprefs & IPV6_PREFER_SRC_MASK) << 3;
}
static inline unsigned int rt6_flags2srcprefs(int flags)
{
- return (flags >> 3) & 7;
+ return (flags >> 3) & IPV6_PREFER_SRC_MASK;
}
static inline bool rt6_need_strict(const struct in6_addr *daddr)
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index bd115980809f386a7d38a5471d8d636f25ce1eba..b3444c8a6f744c17052a9fa1c85d54c6b08a1889 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1306,10 +1306,13 @@ static inline void ip6_sock_set_recverr(struct sock *sk)
inet6_set_bit(RECVERR6, sk);
}
-static inline int __ip6_sock_set_addr_preferences(struct sock *sk, int val)
+#define IPV6_PREFER_SRC_MASK (IPV6_PREFER_SRC_TMP | IPV6_PREFER_SRC_PUBLIC | \
+ IPV6_PREFER_SRC_COA)
+
+static inline int ip6_sock_set_addr_preferences(struct sock *sk, int val)
{
+ unsigned int prefmask = ~IPV6_PREFER_SRC_MASK;
unsigned int pref = 0;
- unsigned int prefmask = ~0;
/* check PUBLIC/TMP/PUBTMP_DEFAULT conflicts */
switch (val & (IPV6_PREFER_SRC_PUBLIC |
@@ -1359,20 +1362,11 @@ static inline int __ip6_sock_set_addr_preferences(struct sock *sk, int val)
return -EINVAL;
}
- inet6_sk(sk)->srcprefs = (inet6_sk(sk)->srcprefs & prefmask) | pref;
+ WRITE_ONCE(inet6_sk(sk)->srcprefs,
+ (READ_ONCE(inet6_sk(sk)->srcprefs) & prefmask) | pref);
return 0;
}
-static inline int ip6_sock_set_addr_preferences(struct sock *sk, int val)
-{
- int ret;
-
- lock_sock(sk);
- ret = __ip6_sock_set_addr_preferences(sk, val);
- release_sock(sk);
- return ret;
-}
-
static inline void ip6_sock_set_recvpktinfo(struct sock *sk)
{
lock_sock(sk);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 7e5d9eeb990fd4549be753fdaaf1e6c6c21d3f8d..951ba8089b5b44c589f1b497e645ffc15a86c7c8 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1113,7 +1113,7 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
rcu_read_lock();
from = rt ? rcu_dereference(rt->from) : NULL;
err = ip6_route_get_saddr(net, from, &fl6->daddr,
- sk ? inet6_sk(sk)->srcprefs : 0,
+ sk ? READ_ONCE(inet6_sk(sk)->srcprefs) : 0,
&fl6->saddr);
rcu_read_unlock();
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index e9dc6f881bb92db267903a71f3f3e4de4c557819..7d661735cb9d519ab4691979f30365acda0a28c3 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -505,6 +505,10 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
return -EINVAL;
inet6_assign_bit(SNDFLOW, sk, valbool);
return 0;
+ case IPV6_ADDR_PREFERENCES:
+ if (optlen < sizeof(int))
+ return -EINVAL;
+ return ip6_sock_set_addr_preferences(sk, val);
}
if (needs_rtnl)
rtnl_lock();
@@ -964,11 +968,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
retv = xfrm_user_policy(sk, optname, optval, optlen);
break;
- case IPV6_ADDR_PREFERENCES:
- if (optlen < sizeof(int))
- goto e_inval;
- retv = __ip6_sock_set_addr_preferences(sk, val);
- break;
case IPV6_RECVFRAGSIZE:
np->rxopt.bits.recvfragsize = valbool;
retv = 0;
@@ -1415,23 +1414,25 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
}
case IPV6_ADDR_PREFERENCES:
+ {
+ u8 srcprefs = READ_ONCE(np->srcprefs);
val = 0;
- if (np->srcprefs & IPV6_PREFER_SRC_TMP)
+ if (srcprefs & IPV6_PREFER_SRC_TMP)
val |= IPV6_PREFER_SRC_TMP;
- else if (np->srcprefs & IPV6_PREFER_SRC_PUBLIC)
+ else if (srcprefs & IPV6_PREFER_SRC_PUBLIC)
val |= IPV6_PREFER_SRC_PUBLIC;
else {
/* XXX: should we return system default? */
val |= IPV6_PREFER_SRC_PUBTMP_DEFAULT;
}
- if (np->srcprefs & IPV6_PREFER_SRC_COA)
+ if (srcprefs & IPV6_PREFER_SRC_COA)
val |= IPV6_PREFER_SRC_COA;
else
val |= IPV6_PREFER_SRC_HOME;
break;
-
+ }
case IPV6_MINHOPCOUNT:
val = READ_ONCE(np->min_hopcount);
break;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 9d8dfc7423e49af6df6ddc95ddf235b0b2b758ef..b132feae3393f313b48fb84fc56e2c2aad37608a 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2622,7 +2622,7 @@ static struct dst_entry *ip6_route_output_flags_noref(struct net *net,
if (!any_src)
flags |= RT6_LOOKUP_F_HAS_SADDR;
else if (sk)
- flags |= rt6_srcprefs2flags(inet6_sk(sk)->srcprefs);
+ flags |= rt6_srcprefs2flags(READ_ONCE(inet6_sk(sk)->srcprefs));
return fib6_rule_lookup(net, fl6, NULL, flags, ip6_pol_route_output);
}
--
2.42.0.459.ge4e396fd5e-goog
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