From: Martin KaFai Lau kafai@fb.com
[ Upstream commit 88d7fcfa3b1fe670f0412b95be785aafca63352b ]
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 jbacik@fb.com Fixes: 637bc8bbe6c0 ("inet: reset tb->fastreuseport when adding a reuseport sk") Signed-off-by: Martin KaFai Lau kafai@fb.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/inet_connection_sock.c | 43 ++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 19 deletions(-)
--- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -24,17 +24,19 @@ #include <net/addrconf.h>
#if IS_ENABLED(CONFIG_IPV6) -/* match_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses if IPv6 - * only, and any IPv4 addresses if not IPv6 only - * match_wildcard == false: addresses must be exactly the same, i.e. - * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY, - * and 0.0.0.0 equals to 0.0.0.0 only +/* match_sk*_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses + * if IPv6 only, and any IPv4 addresses + * if not IPv6 only + * match_sk*_wildcard == false: addresses must be exactly the same, i.e. + * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY, + * and 0.0.0.0 equals to 0.0.0.0 only */ static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6, const struct in6_addr *sk2_rcv_saddr6, __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr, bool sk1_ipv6only, bool sk2_ipv6only, - bool match_wildcard) + bool match_sk1_wildcard, + bool match_sk2_wildcard) { int addr_type = ipv6_addr_type(sk1_rcv_saddr6); int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED; @@ -44,8 +46,8 @@ static bool ipv6_rcv_saddr_equal(const s if (!sk2_ipv6only) { if (sk1_rcv_saddr == sk2_rcv_saddr) return true; - if (!sk1_rcv_saddr || !sk2_rcv_saddr) - return match_wildcard; + return (match_sk1_wildcard && !sk1_rcv_saddr) || + (match_sk2_wildcard && !sk2_rcv_saddr); } return false; } @@ -53,11 +55,11 @@ static bool ipv6_rcv_saddr_equal(const s if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY) return true;
- if (addr_type2 == IPV6_ADDR_ANY && match_wildcard && + if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard && !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED)) return true;
- if (addr_type == IPV6_ADDR_ANY && match_wildcard && + if (addr_type == IPV6_ADDR_ANY && match_sk1_wildcard && !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED)) return true;
@@ -69,18 +71,19 @@ static bool ipv6_rcv_saddr_equal(const s } #endif
-/* match_wildcard == true: 0.0.0.0 equals to any IPv4 addresses - * match_wildcard == false: addresses must be exactly the same, i.e. - * 0.0.0.0 only equals to 0.0.0.0 +/* match_sk*_wildcard == true: 0.0.0.0 equals to any IPv4 addresses + * match_sk*_wildcard == false: addresses must be exactly the same, i.e. + * 0.0.0.0 only equals to 0.0.0.0 */ static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr, - bool sk2_ipv6only, bool match_wildcard) + bool sk2_ipv6only, bool match_sk1_wildcard, + bool match_sk2_wildcard) { if (!sk2_ipv6only) { if (sk1_rcv_saddr == sk2_rcv_saddr) return true; - if (!sk1_rcv_saddr || !sk2_rcv_saddr) - return match_wildcard; + return (match_sk1_wildcard && !sk1_rcv_saddr) || + (match_sk2_wildcard && !sk2_rcv_saddr); } return false; } @@ -96,10 +99,12 @@ bool inet_rcv_saddr_equal(const struct s sk2->sk_rcv_saddr, ipv6_only_sock(sk), ipv6_only_sock(sk2), + match_wildcard, match_wildcard); #endif return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr, - ipv6_only_sock(sk2), match_wildcard); + ipv6_only_sock(sk2), match_wildcard, + match_wildcard); } EXPORT_SYMBOL(inet_rcv_saddr_equal);
@@ -273,10 +278,10 @@ static inline int sk_reuseport_match(str tb->fast_rcv_saddr, sk->sk_rcv_saddr, tb->fast_ipv6_only, - ipv6_only_sock(sk), true); + ipv6_only_sock(sk), true, false); #endif return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr, - ipv6_only_sock(sk), true); + ipv6_only_sock(sk), true, false); }
/* Obtain a reference to a local port for the given sock,