diff options
| -rw-r--r-- | include/net/ip.h | 11 | ||||
| -rw-r--r-- | net/ipv4/route.c | 32 | ||||
| -rw-r--r-- | net/ipv6/ip6_output.c | 2 |
3 files changed, 32 insertions, 13 deletions
diff --git a/include/net/ip.h b/include/net/ip.h index 29c8cd68db8b..937f19681426 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -297,16 +297,7 @@ static inline unsigned int ip_skb_dst_mtu(const struct sk_buff *skb) } } -#define IP_IDENTS_SZ 2048u -extern atomic_t *ip_idents; - -static inline u32 ip_idents_reserve(u32 hash, int segs) -{ - atomic_t *id_ptr = ip_idents + hash % IP_IDENTS_SZ; - - return atomic_add_return(segs, id_ptr) - segs; -} - +u32 ip_idents_reserve(u32 hash, int segs); void __ip_select_ident(struct iphdr *iph, int segs); static inline void ip_select_ident_segs(struct sk_buff *skb, struct sock *sk, int segs) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 2ec273ebc858..ca5a01ed8ed6 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -463,8 +463,31 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst, return neigh_create(&arp_tbl, pkey, dev); } -atomic_t *ip_idents __read_mostly; -EXPORT_SYMBOL(ip_idents); +#define IP_IDENTS_SZ 2048u +struct ip_ident_bucket { + atomic_t id; + u32 stamp32; +}; + +static struct ip_ident_bucket *ip_idents __read_mostly; + +/* In order to protect privacy, we add a perturbation to identifiers + * if one generator is seldom used. This makes hard for an attacker + * to infer how many packets were sent between two points in time. + */ +u32 ip_idents_reserve(u32 hash, int segs) +{ + struct ip_ident_bucket *bucket = ip_idents + hash % IP_IDENTS_SZ; + u32 old = ACCESS_ONCE(bucket->stamp32); + u32 now = (u32)jiffies; + u32 delta = 0; + + if (old != now && cmpxchg(&bucket->stamp32, old, now) == old) + delta = prandom_u32_max(now - old); + + return atomic_add_return(segs + delta, &bucket->id) - segs; +} +EXPORT_SYMBOL(ip_idents_reserve); void __ip_select_ident(struct iphdr *iph, int segs) { @@ -473,7 +496,10 @@ void __ip_select_ident(struct iphdr *iph, int segs) net_get_random_once(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd)); - hash = jhash_1word((__force u32)iph->daddr, ip_idents_hashrnd); + hash = jhash_3words((__force u32)iph->daddr, + (__force u32)iph->saddr, + iph->protocol, + ip_idents_hashrnd); id = ip_idents_reserve(hash, segs); iph->id = htons(id); } diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index b6256da51274..073e5a6fc631 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -545,6 +545,8 @@ static void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) net_get_random_once(&ip6_idents_hashrnd, sizeof(ip6_idents_hashrnd)); hash = __ipv6_addr_jhash(&rt->rt6i_dst.addr, ip6_idents_hashrnd); + hash = __ipv6_addr_jhash(&rt->rt6i_src.addr, hash); + id = ip_idents_reserve(hash, 1); fhdr->identification = htonl(id); } |