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bpf: Fix IPv6 dport byte order in bpf_sk_lookup_udp

PATCH Applied Andrey Ignatov 4 participants 4 messages Nov 8, 2018 – Nov 9, 2018

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Networking Network drivers BPF BPF networking
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Andrey Ignatov

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#0 lore raw

PATCH 1/1 bpf: Fix IPv6 dport byte order in bpf_sk_lookup_udp

Lookup functions in sk_lookup have different expectations about byte order of provided arguments.

Specifically __inet_lookup, __udp4_lib_lookup and __udp6_lib_lookup expect dport to be in network byte order and do ntohs(dport) internally.

At the same time __inet6_lookup expects dport to be in host byte order and correspondingly name the argument hnum.

sk_lookup works correctly with __inet_lookup, __udp4_lib_lookup and __inet6_lookup with regard to dport. But in __udp6_lib_lookup case it uses host instead of expected network byte order. It makes result returned by bpf_sk_lookup_udp for IPv6 incorrect.

The patch fixes byte order of dport passed to __udp6_lib_lookup.

Originally sk_lookup properly handled UDPv6, but not TCPv6. 5ef0ae84f02a fixes TCPv6 but breaks UDPv6.

Fixes 5ef0ae84f02a ("bpf: Fix IPv6 dport byte-order in bpf_sk_lookup")
Signed-off-by Andrey Ignatov <[email protected]>
---
 net/core/filter.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
net/core/filter.c +2 -3
index e521c5ebc7d1..9a1327eb25fa 100644
@@ -4852,18 +4852,17 @@ static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
 	} else {
 		struct in6_addr *src6 = (struct in6_addr *)&tuple->ipv6.saddr;
 		struct in6_addr *dst6 = (struct in6_addr *)&tuple->ipv6.daddr;
-		u16 hnum = ntohs(tuple->ipv6.dport);
 		int sdif = inet6_sdif(skb);
 
 		if (proto == IPPROTO_TCP)
 			sk = __inet6_lookup(net, &tcp_hashinfo, skb, 0,
 					    src6, tuple->ipv6.sport,
-					    dst6, hnum,
+					    dst6, ntohs(tuple->ipv6.dport),
 					    dif, sdif, &refcounted);
 		else if (likely(ipv6_bpf_stub))
 			sk = ipv6_bpf_stub->udp6_lib_lookup(net,
 							    src6, tuple->ipv6.sport,
-							    dst6, hnum,
+							    dst6, tuple->ipv6.dport,
 							    dif, sdif,
 							    &udp_table, skb);
 #endif
Signature · 1 line
2.17.1
Acked-by on v1 1/1
#1 lore raw
Quoted 15 lines · Andrey Ignatov

Lookup functions in sk_lookup have different expectations about byte order of provided arguments.

Specifically __inet_lookup, __udp4_lib_lookup and __udp6_lib_lookup expect dport to be in network byte order and do ntohs(dport) internally.

At the same time __inet6_lookup expects dport to be in host byte order and correspondingly name the argument hnum.

sk_lookup works correctly with __inet_lookup, __udp4_lib_lookup and __inet6_lookup with regard to dport. But in __udp6_lib_lookup case it uses host instead of expected network byte order. It makes result returned by bpf_sk_lookup_udp for IPv6 incorrect.

Quoted 7 lines

The patch fixes byte order of dport passed to __udp6_lib_lookup.

Originally sk_lookup properly handled UDPv6, but not TCPv6. 5ef0ae84f02a fixes TCPv6 but breaks UDPv6.

Fixes 5ef0ae84f02a ("bpf: Fix IPv6 dport byte-order in bpf_sk_lookup")
Signed-off-by Andrey Ignatov <[email protected]>

Thanks for the fix, makes sense.

Acked-by Joe Stringer <[email protected]>
Acked-by on v1 1/1
#2 lore raw
In reply to Andrey Ignatov
Quoted 14 lines · Andrey Ignatov

Lookup functions in sk_lookup have different expectations about byte order of provided arguments.

Specifically __inet_lookup, __udp4_lib_lookup and __udp6_lib_lookup expect dport to be in network byte order and do ntohs(dport) internally.

At the same time __inet6_lookup expects dport to be in host byte order and correspondingly name the argument hnum.

sk_lookup works correctly with __inet_lookup, __udp4_lib_lookup and __inet6_lookup with regard to dport. But in __udp6_lib_lookup case it uses host instead of expected network byte order. It makes result returned by bpf_sk_lookup_udp for IPv6 incorrect.

Quoted 7 lines

The patch fixes byte order of dport passed to __udp6_lib_lookup.

Originally sk_lookup properly handled UDPv6, but not TCPv6. 5ef0ae84f02a fixes TCPv6 but breaks UDPv6.

Fixes 5ef0ae84f02a ("bpf: Fix IPv6 dport byte-order in bpf_sk_lookup")
Signed-off-by Andrey Ignatov <[email protected]>

Good catch.

Acked-by Martin KaFai Lau <[email protected]>
Quoted 32 lines
---
 net/core/filter.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
net/core/filter.c +2 -3
index e521c5ebc7d1..9a1327eb25fa 100644
@@ -4852,18 +4852,17 @@ static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
 	} else {
 		struct in6_addr *src6 = (struct in6_addr *)&tuple->ipv6.saddr;
 		struct in6_addr *dst6 = (struct in6_addr *)&tuple->ipv6.daddr;
-		u16 hnum = ntohs(tuple->ipv6.dport);
 		int sdif = inet6_sdif(skb);
 
 		if (proto == IPPROTO_TCP)
 			sk = __inet6_lookup(net, &tcp_hashinfo, skb, 0,
 					    src6, tuple->ipv6.sport,
-					    dst6, hnum,
+					    dst6, ntohs(tuple->ipv6.dport),
 					    dif, sdif, &refcounted);
 		else if (likely(ipv6_bpf_stub))
 			sk = ipv6_bpf_stub->udp6_lib_lookup(net,
 							    src6, tuple->ipv6.sport,
-							    dst6, hnum,
+							    dst6, tuple->ipv6.dport,
 							    dif, sdif,
 							    &udp_table, skb);
 #endif
Signature · 1 line
2.17.1
maintainer Applied
#3 lore raw
In reply to Andrey Ignatov
Quoted 14 lines · Andrey Ignatov

Lookup functions in sk_lookup have different expectations about byte order of provided arguments.

Specifically __inet_lookup, __udp4_lib_lookup and __udp6_lib_lookup expect dport to be in network byte order and do ntohs(dport) internally.

At the same time __inet6_lookup expects dport to be in host byte order and correspondingly name the argument hnum.

sk_lookup works correctly with __inet_lookup, __udp4_lib_lookup and __inet6_lookup with regard to dport. But in __udp6_lib_lookup case it uses host instead of expected network byte order. It makes result returned by bpf_sk_lookup_udp for IPv6 incorrect.

Quoted 7 lines

The patch fixes byte order of dport passed to __udp6_lib_lookup.

Originally sk_lookup properly handled UDPv6, but not TCPv6. 5ef0ae84f02a fixes TCPv6 but breaks UDPv6.

Fixes 5ef0ae84f02a ("bpf: Fix IPv6 dport byte-order in bpf_sk_lookup")
Signed-off-by Andrey Ignatov <[email protected]>

Applied to bpf, thanks Andrey!