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cf533ea53e
Adding const qualifiers to pointers can ease code review, and spot some bugs. It might allow compiler to optimize code further. For example, is it legal to temporary write a null cksum into tcphdr in tcp_md5_hash_header() ? I am afraid a sniffer could catch the temporary null value... Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
185 lines
4.3 KiB
C
185 lines
4.3 KiB
C
#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/cryptohash.h>
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#include <linux/module.h>
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#include <linux/cache.h>
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#include <linux/random.h>
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#include <linux/hrtimer.h>
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#include <linux/ktime.h>
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#include <linux/string.h>
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#include <net/secure_seq.h>
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static u32 net_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
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static int __init net_secret_init(void)
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{
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get_random_bytes(net_secret, sizeof(net_secret));
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return 0;
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}
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late_initcall(net_secret_init);
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static u32 seq_scale(u32 seq)
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{
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/*
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* As close as possible to RFC 793, which
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* suggests using a 250 kHz clock.
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* Further reading shows this assumes 2 Mb/s networks.
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* For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
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* For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
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* we also need to limit the resolution so that the u32 seq
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* overlaps less than one time per MSL (2 minutes).
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* Choosing a clock of 64 ns period is OK. (period of 274 s)
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*/
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return seq + (ktime_to_ns(ktime_get_real()) >> 6);
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}
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#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
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__u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
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__be16 sport, __be16 dport)
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{
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u32 secret[MD5_MESSAGE_BYTES / 4];
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u32 hash[MD5_DIGEST_WORDS];
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u32 i;
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memcpy(hash, saddr, 16);
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for (i = 0; i < 4; i++)
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secret[i] = net_secret[i] + daddr[i];
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secret[4] = net_secret[4] +
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(((__force u16)sport << 16) + (__force u16)dport);
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for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
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secret[i] = net_secret[i];
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md5_transform(hash, secret);
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return seq_scale(hash[0]);
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}
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EXPORT_SYMBOL(secure_tcpv6_sequence_number);
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u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
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__be16 dport)
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{
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u32 secret[MD5_MESSAGE_BYTES / 4];
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u32 hash[MD5_DIGEST_WORDS];
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u32 i;
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memcpy(hash, saddr, 16);
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for (i = 0; i < 4; i++)
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secret[i] = net_secret[i] + (__force u32) daddr[i];
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secret[4] = net_secret[4] + (__force u32)dport;
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for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
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secret[i] = net_secret[i];
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md5_transform(hash, secret);
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return hash[0];
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}
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#endif
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#ifdef CONFIG_INET
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__u32 secure_ip_id(__be32 daddr)
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{
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u32 hash[MD5_DIGEST_WORDS];
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hash[0] = (__force __u32) daddr;
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hash[1] = net_secret[13];
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hash[2] = net_secret[14];
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hash[3] = net_secret[15];
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md5_transform(hash, net_secret);
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return hash[0];
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}
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__u32 secure_ipv6_id(const __be32 daddr[4])
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{
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__u32 hash[4];
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memcpy(hash, daddr, 16);
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md5_transform(hash, net_secret);
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return hash[0];
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}
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__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
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__be16 sport, __be16 dport)
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{
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u32 hash[MD5_DIGEST_WORDS];
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hash[0] = (__force u32)saddr;
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hash[1] = (__force u32)daddr;
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hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
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hash[3] = net_secret[15];
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md5_transform(hash, net_secret);
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return seq_scale(hash[0]);
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}
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u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
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{
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u32 hash[MD5_DIGEST_WORDS];
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hash[0] = (__force u32)saddr;
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hash[1] = (__force u32)daddr;
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hash[2] = (__force u32)dport ^ net_secret[14];
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hash[3] = net_secret[15];
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md5_transform(hash, net_secret);
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return hash[0];
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}
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EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
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#endif
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#if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
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u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
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__be16 sport, __be16 dport)
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{
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u32 hash[MD5_DIGEST_WORDS];
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u64 seq;
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hash[0] = (__force u32)saddr;
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hash[1] = (__force u32)daddr;
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hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
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hash[3] = net_secret[15];
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md5_transform(hash, net_secret);
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seq = hash[0] | (((u64)hash[1]) << 32);
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seq += ktime_to_ns(ktime_get_real());
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seq &= (1ull << 48) - 1;
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return seq;
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}
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EXPORT_SYMBOL(secure_dccp_sequence_number);
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#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
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u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
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__be16 sport, __be16 dport)
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{
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u32 secret[MD5_MESSAGE_BYTES / 4];
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u32 hash[MD5_DIGEST_WORDS];
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u64 seq;
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u32 i;
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memcpy(hash, saddr, 16);
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for (i = 0; i < 4; i++)
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secret[i] = net_secret[i] + daddr[i];
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secret[4] = net_secret[4] +
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(((__force u16)sport << 16) + (__force u16)dport);
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for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
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secret[i] = net_secret[i];
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md5_transform(hash, secret);
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seq = hash[0] | (((u64)hash[1]) << 32);
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seq += ktime_to_ns(ktime_get_real());
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seq &= (1ull << 48) - 1;
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return seq;
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}
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EXPORT_SYMBOL(secure_dccpv6_sequence_number);
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#endif
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#endif
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