// 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/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 <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_key_t net_secret __read_mostly; static siphash_key_t ts_secret __read_mostly; static __always_inline void net_secret_init(void) { net_get_random_once(&net_secret, sizeof(net_secret)); } static __always_inline void ts_secret_init(void) { net_get_random_once(&ts_secret, sizeof(ts_secret)); } #endif #ifdef CONFIG_INET 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_get_real_ns() >> 6); } #endif #if IS_ENABLED(CONFIG_IPV6) u32 secure_tcpv6_ts_off(const struct net *net, const __be32 *saddr, const __be32 *daddr) { const struct { struct in6_addr saddr; struct in6_addr daddr; } __aligned(SIPHASH_ALIGNMENT) combined = { .saddr = *(struct in6_addr *)saddr, .daddr = *(struct in6_addr *)daddr, }; if (net->ipv4.sysctl_tcp_timestamps != 1) return 0; ts_secret_init(); return siphash(&combined, offsetofend(typeof(combined), daddr), &ts_secret); } EXPORT_SYMBOL(secure_tcpv6_ts_off); u32 secure_tcpv6_seq(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 }; u32 hash; net_secret_init(); hash = siphash(&combined, offsetofend(typeof(combined), dport), &net_secret); return seq_scale(hash); } EXPORT_SYMBOL(secure_tcpv6_seq); u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr, __be16 dport) { const struct { struct in6_addr saddr; struct in6_addr daddr; __be16 dport; } __aligned(SIPHASH_ALIGNMENT) combined = { .saddr = *(struct in6_addr *)saddr, .daddr = *(struct in6_addr *)daddr, .dport = dport }; net_secret_init(); return siphash(&combined, offsetofend(typeof(combined), dport), &net_secret); } EXPORT_SYMBOL(secure_ipv6_port_ephemeral); #endif #ifdef CONFIG_INET u32 secure_tcp_ts_off(const struct net *net, __be32 saddr, __be32 daddr) { if (net->ipv4.sysctl_tcp_timestamps != 1) return 0; ts_secret_init(); return siphash_2u32((__force u32)saddr, (__force u32)daddr, &ts_secret); } /* 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. */ u32 secure_tcp_seq(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport) { u32 hash; net_secret_init(); hash = siphash_3u32((__force u32)saddr, (__force u32)daddr, (__force u32)sport << 16 | (__force u32)dport, &net_secret); return seq_scale(hash); } EXPORT_SYMBOL_GPL(secure_tcp_seq); u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport) { net_secret_init(); return siphash_3u32((__force u32)saddr, (__force u32)daddr, (__force u16)dport, &net_secret); } EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral); #endif #if IS_ENABLED(CONFIG_IP_DCCP) u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport) { u64 seq; net_secret_init(); seq = siphash_3u32((__force u32)saddr, (__force u32)daddr, (__force u32)sport << 16 | (__force u32)dport, &net_secret); seq += ktime_get_real_ns(); seq &= (1ull << 48) - 1; return seq; } EXPORT_SYMBOL(secure_dccp_sequence_number); #if IS_ENABLED(CONFIG_IPV6) u64 secure_dccpv6_sequence_number(__be32 *saddr, __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 }; u64 seq; net_secret_init(); seq = siphash(&combined, offsetofend(typeof(combined), dport), &net_secret); seq += ktime_get_real_ns(); seq &= (1ull << 48) - 1; return seq; } EXPORT_SYMBOL(secure_dccpv6_sequence_number); #endif #endif