// 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;static siphash_aligned_key_t ts_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));} static __always_inline void ts_secret_init(void){	net_get_random_once(&ts_secret, sizeof(ts_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)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 (READ_ONCE(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); 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_INETu32 secure_tcp_ts_off(const struct net *net, __be32 saddr, __be32 daddr){	if (READ_ONCE(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); 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 #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