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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
#include <linux/kernel.h>#include <linux/init.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 <linux/net.h>#include <linux/siphash.h>#include <net/secure_seq.h>
#if IS_ENABLED(CONFIG_IPV6) || IS_ENABLED(CONFIG_INET)#include <linux/in6.h>#include <net/tcp.h>
static siphash_aligned_key_t net_secret;
#define EPHEMERAL_PORT_SHUFFLE_PERIOD (10 * HZ)
static __always_inline void net_secret_init(void){ net_get_random_once(&net_secret, sizeof(net_secret));}#endif
#ifdef CONFIG_INETstatic 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_get_real_ns() >> 6);}#endif
#if IS_ENABLED(CONFIG_IPV6)union tcp_seq_and_ts_offsecure_tcpv6_seq_and_ts_off(const struct net *net, const __be32 *saddr, const __be32 *daddr, __be16 sport, __be16 dport){ const struct { struct in6_addr saddr; struct in6_addr daddr; __be16 sport; __be16 dport; } __aligned(SIPHASH_ALIGNMENT) combined = { .saddr = *(struct in6_addr *)saddr, .daddr = *(struct in6_addr *)daddr, .sport = sport, .dport = dport }; union tcp_seq_and_ts_off st;
net_secret_init();
st.hash64 = siphash(&combined, offsetofend(typeof(combined), dport), &net_secret);
if (READ_ONCE(net->ipv4.sysctl_tcp_timestamps) != 1) st.ts_off = 0;
st.seq = seq_scale(st.seq); return st;}EXPORT_SYMBOL(secure_tcpv6_seq_and_ts_off);
u64 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr, __be16 dport){ const struct { struct in6_addr saddr; struct in6_addr daddr; unsigned int timeseed; __be16 dport; } __aligned(SIPHASH_ALIGNMENT) combined = { .saddr = *(struct in6_addr *)saddr, .daddr = *(struct in6_addr *)daddr, .timeseed = jiffies / EPHEMERAL_PORT_SHUFFLE_PERIOD, .dport = dport, }; net_secret_init(); return siphash(&combined, offsetofend(typeof(combined), dport), &net_secret);}EXPORT_SYMBOL(secure_ipv6_port_ephemeral);#endif
#ifdef CONFIG_INET/* secure_tcp_seq_and_tsoff(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d), * but fortunately, `sport' cannot be 0 in any circumstances. If this changes, * it would be easy enough to have the former function use siphash_4u32, passing * the arguments as separate u32. */union tcp_seq_and_ts_offsecure_tcp_seq_and_ts_off(const struct net *net, __be32 saddr, __be32 daddr, __be16 sport, __be16 dport){ u32 ports = (__force u32)sport << 16 | (__force u32)dport; union tcp_seq_and_ts_off st;
net_secret_init();
st.hash64 = siphash_3u32((__force u32)saddr, (__force u32)daddr, ports, &net_secret);
if (READ_ONCE(net->ipv4.sysctl_tcp_timestamps) != 1) st.ts_off = 0;
st.seq = seq_scale(st.seq); return st;}EXPORT_SYMBOL_GPL(secure_tcp_seq_and_ts_off);
u64 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport){ net_secret_init(); return siphash_4u32((__force u32)saddr, (__force u32)daddr, (__force u16)dport, jiffies / EPHEMERAL_PORT_SHUFFLE_PERIOD, &net_secret);}EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);#endif