net: Compute protocol sequence numbers and fragment IDs using MD5, CVE-2011-3188

[linux-flexiantxendom0-natty.git] / net / core / secure_seq.c

diff --git a/net/core/secure_seq.c b/net/core/secure_seq.c
new file mode 100644 (file)
index 0000000..45329d7
--- /dev/null
+++ b/net/core/secure_seq.c
@@ -0,0 +1,184 @@
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/cryptohash.h>
+#include <linux/module.h>
+#include <linux/cache.h>
+#include <linux/random.h>
+#include <linux/hrtimer.h>
+#include <linux/ktime.h>
+#include <linux/string.h>
+
+#include <net/secure_seq.h>
+
+static u32 net_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
+
+static int __init net_secret_init(void)
+{
+       get_random_bytes(net_secret, sizeof(net_secret));
+       return 0;
+}
+late_initcall(net_secret_init);
+
+static u32 seq_scale(u32 seq)
+{
+       /*
+        *      As close as possible to RFC 793, which
+        *      suggests using a 250 kHz clock.
+        *      Further reading shows this assumes 2 Mb/s networks.
+        *      For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
+        *      For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
+        *      we also need to limit the resolution so that the u32 seq
+        *      overlaps less than one time per MSL (2 minutes).
+        *      Choosing a clock of 64 ns period is OK. (period of 274 s)
+        */
+       return seq + (ktime_to_ns(ktime_get_real()) >> 6);
+}
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+__u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr,
+                                  __be16 sport, __be16 dport)
+{
+       u32 secret[MD5_MESSAGE_BYTES / 4];
+       u32 hash[MD5_DIGEST_WORDS];
+       u32 i;
+
+       memcpy(hash, saddr, 16);
+       for (i = 0; i < 4; i++)
+               secret[i] = net_secret[i] + daddr[i];
+       secret[4] = net_secret[4] +
+               (((__force u16)sport << 16) + (__force u16)dport);
+       for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
+               secret[i] = net_secret[i];
+
+       md5_transform(hash, secret);
+
+       return seq_scale(hash[0]);
+}
+EXPORT_SYMBOL(secure_tcpv6_sequence_number);
+
+u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
+                              __be16 dport)
+{
+       u32 secret[MD5_MESSAGE_BYTES / 4];
+       u32 hash[MD5_DIGEST_WORDS];
+       u32 i;
+
+       memcpy(hash, saddr, 16);
+       for (i = 0; i < 4; i++)
+               secret[i] = net_secret[i] + (__force u32) daddr[i];
+       secret[4] = net_secret[4] + (__force u32)dport;
+       for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
+               secret[i] = net_secret[i];
+
+       md5_transform(hash, secret);
+
+       return hash[0];
+}
+#endif
+
+#ifdef CONFIG_INET
+__u32 secure_ip_id(__be32 daddr)
+{
+       u32 hash[MD5_DIGEST_WORDS];
+
+       hash[0] = (__force __u32) daddr;
+       hash[1] = net_secret[13];
+       hash[2] = net_secret[14];
+       hash[3] = net_secret[15];
+
+       md5_transform(hash, net_secret);
+
+       return hash[0];
+}
+
+__u32 secure_ipv6_id(const __be32 daddr[4])
+{
+       __u32 hash[4];
+
+       memcpy(hash, daddr, 16);
+       md5_transform(hash, net_secret);
+
+       return hash[0];
+}
+
+__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
+                                __be16 sport, __be16 dport)
+{
+       u32 hash[MD5_DIGEST_WORDS];
+
+       hash[0] = (__force u32)saddr;
+       hash[1] = (__force u32)daddr;
+       hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
+       hash[3] = net_secret[15];
+
+       md5_transform(hash, net_secret);
+
+       return seq_scale(hash[0]);
+}
+
+u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
+{
+       u32 hash[MD5_DIGEST_WORDS];
+
+       hash[0] = (__force u32)saddr;
+       hash[1] = (__force u32)daddr;
+       hash[2] = (__force u32)dport ^ net_secret[14];
+       hash[3] = net_secret[15];
+
+       md5_transform(hash, net_secret);
+
+       return hash[0];
+}
+EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
+#endif
+
+#if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
+u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
+                               __be16 sport, __be16 dport)
+{
+       u32 hash[MD5_DIGEST_WORDS];
+       u64 seq;
+
+       hash[0] = (__force u32)saddr;
+       hash[1] = (__force u32)daddr;
+       hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
+       hash[3] = net_secret[15];
+
+       md5_transform(hash, net_secret);
+
+       seq = hash[0] | (((u64)hash[1]) << 32);
+       seq += ktime_to_ns(ktime_get_real());
+       seq &= (1ull << 48) - 1;
+
+       return seq;
+}
+EXPORT_SYMBOL(secure_dccp_sequence_number);
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
+                                 __be16 sport, __be16 dport)
+{
+       u32 secret[MD5_MESSAGE_BYTES / 4];
+       u32 hash[MD5_DIGEST_WORDS];
+       u64 seq;
+       u32 i;
+
+       memcpy(hash, saddr, 16);
+       for (i = 0; i < 4; i++)
+               secret[i] = net_secret[i] + daddr[i];
+       secret[4] = net_secret[4] +
+               (((__force u16)sport << 16) + (__force u16)dport);
+       for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
+               secret[i] = net_secret[i];
+
+       md5_transform(hash, secret);
+
+       seq = hash[0] | (((u64)hash[1]) << 32);
+       seq += ktime_to_ns(ktime_get_real());
+       seq &= (1ull << 48) - 1;
+
+       return seq;
+}
+EXPORT_SYMBOL(secure_dccpv6_sequence_number);
+#endif
+#endif