From e7b519ba55aeb675daee1d304e80d752c385f7f0 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Wed, 23 Oct 2013 11:06:55 +0200 Subject: [PATCH 1/3] ipv4: initialize ip4_frags hash secret as late as possible Defer the generation of the first hash secret for the ipv4 fragmentation cache as late as possible. ip4_frags.rnd gets initial seeded by inet_frags_init and regulary reseeded by inet_frag_secret_rebuild. Either we call ipqhashfn directly from ip_fragment.c in which case we initialize the secret directly. If we first get called by inet_frag_secret_rebuild we install a new secret by a manual call to get_random_bytes. This secret will be overwritten as soon as the first call to ipqhashfn happens. This is safe because we won't race while publishing the new secrets with anyone else. Cc: Eric Dumazet Cc: "David S. Miller" Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv4/ip_fragment.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index b66910aaef4d..2481993a4970 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -106,6 +106,7 @@ struct ip4_create_arg { static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) { + net_get_random_once(&ip4_frags.rnd, sizeof(ip4_frags.rnd)); return jhash_3words((__force u32)id << 16 | prot, (__force u32)saddr, (__force u32)daddr, ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1); From b1190570b451fb9fd77be8c115fcdb418c5108a5 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Wed, 23 Oct 2013 11:06:56 +0200 Subject: [PATCH 2/3] ipv6: split inet6_hash_frag for netfilter and initialize secrets with net_get_random_once Defer the fragmentation hash secret initialization for IPv6 like the previous patch did for IPv4. Because the netfilter logic reuses the hash secret we have to split it first. Thus introduce a new nf_hash_frag function which takes care to seed the hash secret. Cc: David S. Miller Cc: Eric Dumazet Cc: Pablo Neira Ayuso Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- include/net/ipv6.h | 2 -- net/ipv6/netfilter/nf_conntrack_reasm.c | 16 ++++++++++++++-- net/ipv6/reassembly.c | 12 ++++++------ 3 files changed, 20 insertions(+), 10 deletions(-) diff --git a/include/net/ipv6.h b/include/net/ipv6.h index a35055f4f8da..dd96638ab8ff 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -805,8 +805,6 @@ int ip6_mc_source(int add, int omode, struct sock *sk, int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf); int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf, struct group_filter __user *optval, int __user *optlen); -unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr, - const struct in6_addr *daddr, u32 rnd); #ifdef CONFIG_PROC_FS int ac6_proc_init(struct net *net); diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index dffdc1a389c5..4a258263d8ec 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -144,12 +144,24 @@ static inline u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h) return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK); } +static unsigned int nf_hash_frag(__be32 id, const struct in6_addr *saddr, + const struct in6_addr *daddr) +{ + u32 c; + + net_get_random_once(&nf_frags.rnd, sizeof(nf_frags.rnd)); + c = jhash_3words(ipv6_addr_hash(saddr), ipv6_addr_hash(daddr), + (__force u32)id, nf_frags.rnd); + return c & (INETFRAGS_HASHSZ - 1); +} + + static unsigned int nf_hashfn(struct inet_frag_queue *q) { const struct frag_queue *nq; nq = container_of(q, struct frag_queue, q); - return inet6_hash_frag(nq->id, &nq->saddr, &nq->daddr, nf_frags.rnd); + return nf_hash_frag(nq->id, &nq->saddr, &nq->daddr); } static void nf_skb_free(struct sk_buff *skb) @@ -185,7 +197,7 @@ static inline struct frag_queue *fq_find(struct net *net, __be32 id, arg.ecn = ecn; read_lock_bh(&nf_frags.lock); - hash = inet6_hash_frag(id, src, dst, nf_frags.rnd); + hash = nf_hash_frag(id, src, dst); q = inet_frag_find(&net->nf_frag.frags, &nf_frags, &arg, hash); local_bh_enable(); diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index 1aeb473b2cc6..cc85a9ba5010 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -82,24 +82,24 @@ static int ip6_frag_reasm(struct frag_queue *fq, struct sk_buff *prev, * callers should be careful not to use the hash value outside the ipfrag_lock * as doing so could race with ipfrag_hash_rnd being recalculated. */ -unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr, - const struct in6_addr *daddr, u32 rnd) +static unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr, + const struct in6_addr *daddr) { u32 c; + net_get_random_once(&ip6_frags.rnd, sizeof(ip6_frags.rnd)); c = jhash_3words(ipv6_addr_hash(saddr), ipv6_addr_hash(daddr), - (__force u32)id, rnd); + (__force u32)id, ip6_frags.rnd); return c & (INETFRAGS_HASHSZ - 1); } -EXPORT_SYMBOL_GPL(inet6_hash_frag); static unsigned int ip6_hashfn(struct inet_frag_queue *q) { struct frag_queue *fq; fq = container_of(q, struct frag_queue, q); - return inet6_hash_frag(fq->id, &fq->saddr, &fq->daddr, ip6_frags.rnd); + return inet6_hash_frag(fq->id, &fq->saddr, &fq->daddr); } bool ip6_frag_match(struct inet_frag_queue *q, void *a) @@ -193,7 +193,7 @@ fq_find(struct net *net, __be32 id, const struct in6_addr *src, arg.ecn = ecn; read_lock(&ip6_frags.lock); - hash = inet6_hash_frag(id, src, dst, ip6_frags.rnd); + hash = inet6_hash_frag(id, src, dst); q = inet_frag_find(&net->ipv6.frags, &ip6_frags, &arg, hash); if (IS_ERR_OR_NULL(q)) { From 7088ad74e6e710d0c80ea2cead9500f47a2a5d58 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Wed, 23 Oct 2013 11:06:57 +0200 Subject: [PATCH 3/3] inet: remove old fragmentation hash initializing All fragmentation hash secrets now get initialized by their corresponding hash function with net_get_random_once. Thus we can eliminate the initial seeding. Also provide a comment that hash secret seeding happens at the first call to the corresponding hashing function. Cc: David S. Miller Cc: Eric Dumazet Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- include/net/inet_frag.h | 4 ++++ net/ipv4/inet_fragment.c | 3 --- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index bfcbc0017950..6f59de98dabd 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -64,6 +64,10 @@ struct inet_frags { rwlock_t lock ____cacheline_aligned_in_smp; int secret_interval; struct timer_list secret_timer; + + /* The first call to hashfn is responsible to initialize + * rnd. This is best done with net_get_random_once. + */ u32 rnd; int qsize; diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index c5313a9c019b..bb075fc9a14f 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -93,9 +93,6 @@ void inet_frags_init(struct inet_frags *f) } rwlock_init(&f->lock); - f->rnd = (u32) ((totalram_pages ^ (totalram_pages >> 7)) ^ - (jiffies ^ (jiffies >> 6))); - setup_timer(&f->secret_timer, inet_frag_secret_rebuild, (unsigned long)f); f->secret_timer.expires = jiffies + f->secret_interval;