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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2019-06-19 23:46:28 +0200
committerDavid S. Miller <davem@davemloft.net>2019-06-22 16:30:37 -0700
commit438ac88009bcb10f9ced07fbb4b32d5377ee936b (patch)
treea28dc489c5852e2894a04478bdd0f37ffe010ad5
parentMerge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net (diff)
downloadlinux-dev-438ac88009bcb10f9ced07fbb4b32d5377ee936b.tar.xz
linux-dev-438ac88009bcb10f9ced07fbb4b32d5377ee936b.zip
net: fastopen: robustness and endianness fixes for SipHash
Some changes to the TCP fastopen code to make it more robust against future changes in the choice of key/cookie size, etc. - Instead of keeping the SipHash key in an untyped u8[] buffer and casting it to the right type upon use, use the correct type directly. This ensures that the key will appear at the correct alignment if we ever change the way these data structures are allocated. (Currently, they are only allocated via kmalloc so they always appear at the correct alignment) - Use DIV_ROUND_UP when sizing the u64[] array to hold the cookie, so it is always of sufficient size, even if TCP_FASTOPEN_COOKIE_MAX is no longer a multiple of 8. - Drop the 'len' parameter from the tcp_fastopen_reset_cipher() function, which is no longer used. - Add endian swabbing when setting the keys and calculating the hash, to ensure that cookie values are the same for a given key and source/destination address pair regardless of the endianness of the server. Note that none of these are functional changes wrt the current state of the code, with the exception of the swabbing, which only affects big endian systems. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/tcp.h2
-rw-r--r--include/net/tcp.h8
-rw-r--r--net/ipv4/sysctl_net_ipv4.c3
-rw-r--r--net/ipv4/tcp.c3
-rw-r--r--net/ipv4/tcp_fastopen.c35
5 files changed, 24 insertions, 27 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 2689b0b0b68a..f3a85a7fb4b1 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -58,7 +58,7 @@ static inline unsigned int tcp_optlen(const struct sk_buff *skb)
/* TCP Fast Open Cookie as stored in memory */
struct tcp_fastopen_cookie {
- u64 val[TCP_FASTOPEN_COOKIE_MAX / sizeof(u64)];
+ __le64 val[DIV_ROUND_UP(TCP_FASTOPEN_COOKIE_MAX, sizeof(u64))];
s8 len;
bool exp; /* In RFC6994 experimental option format */
};
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 573c9e9b0d72..9d36cc88d043 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -43,6 +43,7 @@
#include <linux/seq_file.h>
#include <linux/memcontrol.h>
#include <linux/bpf-cgroup.h>
+#include <linux/siphash.h>
extern struct inet_hashinfo tcp_hashinfo;
@@ -1612,8 +1613,7 @@ void tcp_free_fastopen_req(struct tcp_sock *tp);
void tcp_fastopen_destroy_cipher(struct sock *sk);
void tcp_fastopen_ctx_destroy(struct net *net);
int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
- void *primary_key, void *backup_key,
- unsigned int len);
+ void *primary_key, void *backup_key);
void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
@@ -1623,14 +1623,14 @@ void tcp_fastopen_init_key_once(struct net *net);
bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
struct tcp_fastopen_cookie *cookie);
bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
-#define TCP_FASTOPEN_KEY_LENGTH 16
+#define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
#define TCP_FASTOPEN_KEY_MAX 2
#define TCP_FASTOPEN_KEY_BUF_LENGTH \
(TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
/* Fastopen key context */
struct tcp_fastopen_context {
- __u8 key[TCP_FASTOPEN_KEY_MAX][TCP_FASTOPEN_KEY_LENGTH];
+ siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
int num;
struct rcu_head rcu;
};
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 7d802acde040..7d66306b5f39 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -365,8 +365,7 @@ static int proc_tcp_fastopen_key(struct ctl_table *table, int write,
}
}
tcp_fastopen_reset_cipher(net, NULL, key,
- backup_data ? key + 4 : NULL,
- TCP_FASTOPEN_KEY_LENGTH);
+ backup_data ? key + 4 : NULL);
}
bad_key:
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index efd7f2b1d1f0..47c217905864 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2822,8 +2822,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
if (optlen == TCP_FASTOPEN_KEY_BUF_LENGTH)
backup_key = key + TCP_FASTOPEN_KEY_LENGTH;
- return tcp_fastopen_reset_cipher(net, sk, key, backup_key,
- TCP_FASTOPEN_KEY_LENGTH);
+ return tcp_fastopen_reset_cipher(net, sk, key, backup_key);
}
default:
/* fallthru */
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index f918599181dd..3fd451271a70 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -7,7 +7,6 @@
#include <linux/tcp.h>
#include <linux/rcupdate.h>
#include <linux/rculist.h>
-#include <linux/siphash.h>
#include <net/inetpeer.h>
#include <net/tcp.h>
@@ -31,7 +30,7 @@ void tcp_fastopen_init_key_once(struct net *net)
* for a valid cookie, so this is an acceptable risk.
*/
get_random_bytes(key, sizeof(key));
- tcp_fastopen_reset_cipher(net, NULL, key, NULL, sizeof(key));
+ tcp_fastopen_reset_cipher(net, NULL, key, NULL);
}
static void tcp_fastopen_ctx_free(struct rcu_head *head)
@@ -68,8 +67,7 @@ void tcp_fastopen_ctx_destroy(struct net *net)
}
int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
- void *primary_key, void *backup_key,
- unsigned int len)
+ void *primary_key, void *backup_key)
{
struct tcp_fastopen_context *ctx, *octx;
struct fastopen_queue *q;
@@ -81,9 +79,11 @@ int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
goto out;
}
- memcpy(ctx->key[0], primary_key, len);
+ ctx->key[0].key[0] = get_unaligned_le64(primary_key);
+ ctx->key[0].key[1] = get_unaligned_le64(primary_key + 8);
if (backup_key) {
- memcpy(ctx->key[1], backup_key, len);
+ ctx->key[1].key[0] = get_unaligned_le64(backup_key);
+ ctx->key[1].key[1] = get_unaligned_le64(backup_key + 8);
ctx->num = 2;
} else {
ctx->num = 1;
@@ -110,19 +110,18 @@ out:
static bool __tcp_fastopen_cookie_gen_cipher(struct request_sock *req,
struct sk_buff *syn,
- const u8 *key,
+ const siphash_key_t *key,
struct tcp_fastopen_cookie *foc)
{
- BUILD_BUG_ON(TCP_FASTOPEN_KEY_LENGTH != sizeof(siphash_key_t));
BUILD_BUG_ON(TCP_FASTOPEN_COOKIE_SIZE != sizeof(u64));
if (req->rsk_ops->family == AF_INET) {
const struct iphdr *iph = ip_hdr(syn);
- foc->val[0] = siphash(&iph->saddr,
- sizeof(iph->saddr) +
- sizeof(iph->daddr),
- (const siphash_key_t *)key);
+ foc->val[0] = cpu_to_le64(siphash(&iph->saddr,
+ sizeof(iph->saddr) +
+ sizeof(iph->daddr),
+ key));
foc->len = TCP_FASTOPEN_COOKIE_SIZE;
return true;
}
@@ -130,10 +129,10 @@ static bool __tcp_fastopen_cookie_gen_cipher(struct request_sock *req,
if (req->rsk_ops->family == AF_INET6) {
const struct ipv6hdr *ip6h = ipv6_hdr(syn);
- foc->val[0] = siphash(&ip6h->saddr,
- sizeof(ip6h->saddr) +
- sizeof(ip6h->daddr),
- (const siphash_key_t *)key);
+ foc->val[0] = cpu_to_le64(siphash(&ip6h->saddr,
+ sizeof(ip6h->saddr) +
+ sizeof(ip6h->daddr),
+ key));
foc->len = TCP_FASTOPEN_COOKIE_SIZE;
return true;
}
@@ -154,7 +153,7 @@ static void tcp_fastopen_cookie_gen(struct sock *sk,
rcu_read_lock();
ctx = tcp_fastopen_get_ctx(sk);
if (ctx)
- __tcp_fastopen_cookie_gen_cipher(req, syn, ctx->key[0], foc);
+ __tcp_fastopen_cookie_gen_cipher(req, syn, &ctx->key[0], foc);
rcu_read_unlock();
}
@@ -218,7 +217,7 @@ static int tcp_fastopen_cookie_gen_check(struct sock *sk,
if (!ctx)
goto out;
for (i = 0; i < tcp_fastopen_context_len(ctx); i++) {
- __tcp_fastopen_cookie_gen_cipher(req, syn, ctx->key[i], foc);
+ __tcp_fastopen_cookie_gen_cipher(req, syn, &ctx->key[i], foc);
if (tcp_fastopen_cookie_match(foc, orig)) {
ret = i + 1;
goto out;