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authorHannes Frederic Sowa <hannes@stressinduktion.org>2014-03-30 18:28:03 +0200
committerDavid S. Miller <davem@davemloft.net>2014-03-31 16:33:38 -0400
commit6dfac5c33620de7f5ecd9dd07e2e2bb6549c4d55 (patch)
treec3c3fd552b53f016c85aebdf035a83d4f06f582d /net/ipv6/output_core.c
parenta50e233c50dbc881abaa0e4070789064e8d12d70 (diff)
ipv6: strengthen fallback fragmentation id generation
First off, we don't need to check for non-NULL rt any more, as we are guaranteed to always get a valid rt6_info. Drop the check. In case we couldn't allocate an inet_peer for fragmentation information we currently generate strictly incrementing fragmentation ids for all destination. This is done to maximize the cycle and avoid collisions. Those fragmentation ids are very predictable. At least we should try to mix in the destination address. While it should make no difference to simply use a PRNG at this point, secure_ipv6_id ensures that we don't leak information from prandom, so its internal state could be recoverable. This fallback function should normally not get used thus this should not affect performance at all. It is just meant as a safety net. Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/output_core.c')
-rw-r--r--net/ipv6/output_core.c27
1 files changed, 15 insertions, 12 deletions
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index d1b35d377e62..6313abd53c9d 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -6,24 +6,24 @@
#include <net/ipv6.h>
#include <net/ip6_fib.h>
#include <net/addrconf.h>
+#include <net/secure_seq.h>
void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
{
static atomic_t ipv6_fragmentation_id;
+ struct in6_addr addr;
int old, new;
#if IS_ENABLED(CONFIG_IPV6)
- if (rt) {
- struct inet_peer *peer;
- struct net *net;
-
- net = dev_net(rt->dst.dev);
- peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1);
- if (peer) {
- fhdr->identification = htonl(inet_getid(peer, 0));
- inet_putpeer(peer);
- return;
- }
+ struct inet_peer *peer;
+ struct net *net;
+
+ net = dev_net(rt->dst.dev);
+ peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1);
+ if (peer) {
+ fhdr->identification = htonl(inet_getid(peer, 0));
+ inet_putpeer(peer);
+ return;
}
#endif
do {
@@ -32,7 +32,10 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt)
if (!new)
new = 1;
} while (atomic_cmpxchg(&ipv6_fragmentation_id, old, new) != old);
- fhdr->identification = htonl(new);
+
+ addr = rt->rt6i_dst.addr;
+ addr.s6_addr32[0] ^= (__force __be32)new;
+ fhdr->identification = htonl(secure_ipv6_id(addr.s6_addr32));
}
EXPORT_SYMBOL(ipv6_select_ident);

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