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194 lines
4.9 KiB
194 lines
4.9 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright (C) 2016 Jason A. Donenfeld <[email protected]>. All Rights Reserved. |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/init.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 <linux/net.h> |
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#include <linux/siphash.h> |
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#include <net/secure_seq.h> |
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#if IS_ENABLED(CONFIG_IPV6) || IS_ENABLED(CONFIG_INET) |
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#include <linux/in6.h> |
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#include <net/tcp.h> |
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static siphash_key_t net_secret __read_mostly; |
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static siphash_key_t ts_secret __read_mostly; |
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static __always_inline void net_secret_init(void) |
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{ |
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net_get_random_once(&net_secret, sizeof(net_secret)); |
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} |
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static __always_inline void ts_secret_init(void) |
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{ |
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net_get_random_once(&ts_secret, sizeof(ts_secret)); |
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} |
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#endif |
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#ifdef CONFIG_INET |
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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_get_real_ns() >> 6); |
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} |
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#endif |
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#if IS_ENABLED(CONFIG_IPV6) |
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u32 secure_tcpv6_ts_off(const struct net *net, |
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const __be32 *saddr, const __be32 *daddr) |
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{ |
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const struct { |
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struct in6_addr saddr; |
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struct in6_addr daddr; |
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} __aligned(SIPHASH_ALIGNMENT) combined = { |
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.saddr = *(struct in6_addr *)saddr, |
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.daddr = *(struct in6_addr *)daddr, |
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}; |
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if (net->ipv4.sysctl_tcp_timestamps != 1) |
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return 0; |
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ts_secret_init(); |
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return siphash(&combined, offsetofend(typeof(combined), daddr), |
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&ts_secret); |
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} |
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EXPORT_SYMBOL(secure_tcpv6_ts_off); |
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u32 secure_tcpv6_seq(const __be32 *saddr, const __be32 *daddr, |
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__be16 sport, __be16 dport) |
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{ |
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const struct { |
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struct in6_addr saddr; |
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struct in6_addr daddr; |
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__be16 sport; |
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__be16 dport; |
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} __aligned(SIPHASH_ALIGNMENT) combined = { |
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.saddr = *(struct in6_addr *)saddr, |
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.daddr = *(struct in6_addr *)daddr, |
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.sport = sport, |
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.dport = dport |
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}; |
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u32 hash; |
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net_secret_init(); |
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hash = siphash(&combined, offsetofend(typeof(combined), dport), |
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&net_secret); |
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return seq_scale(hash); |
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} |
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EXPORT_SYMBOL(secure_tcpv6_seq); |
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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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const struct { |
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struct in6_addr saddr; |
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struct in6_addr daddr; |
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__be16 dport; |
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} __aligned(SIPHASH_ALIGNMENT) combined = { |
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.saddr = *(struct in6_addr *)saddr, |
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.daddr = *(struct in6_addr *)daddr, |
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.dport = dport |
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}; |
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net_secret_init(); |
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return siphash(&combined, offsetofend(typeof(combined), dport), |
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&net_secret); |
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} |
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EXPORT_SYMBOL(secure_ipv6_port_ephemeral); |
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#endif |
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#ifdef CONFIG_INET |
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u32 secure_tcp_ts_off(const struct net *net, __be32 saddr, __be32 daddr) |
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{ |
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if (net->ipv4.sysctl_tcp_timestamps != 1) |
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return 0; |
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ts_secret_init(); |
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return siphash_2u32((__force u32)saddr, (__force u32)daddr, |
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&ts_secret); |
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} |
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/* secure_tcp_seq_and_tsoff(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d), |
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* but fortunately, `sport' cannot be 0 in any circumstances. If this changes, |
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* it would be easy enough to have the former function use siphash_4u32, passing |
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* the arguments as separate u32. |
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*/ |
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u32 secure_tcp_seq(__be32 saddr, __be32 daddr, |
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__be16 sport, __be16 dport) |
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{ |
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u32 hash; |
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net_secret_init(); |
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hash = siphash_3u32((__force u32)saddr, (__force u32)daddr, |
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(__force u32)sport << 16 | (__force u32)dport, |
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&net_secret); |
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return seq_scale(hash); |
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} |
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EXPORT_SYMBOL_GPL(secure_tcp_seq); |
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u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport) |
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{ |
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net_secret_init(); |
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return siphash_3u32((__force u32)saddr, (__force u32)daddr, |
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(__force u16)dport, &net_secret); |
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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 IS_ENABLED(CONFIG_IP_DCCP) |
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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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u64 seq; |
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net_secret_init(); |
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seq = siphash_3u32((__force u32)saddr, (__force u32)daddr, |
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(__force u32)sport << 16 | (__force u32)dport, |
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&net_secret); |
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seq += ktime_get_real_ns(); |
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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 IS_ENABLED(CONFIG_IPV6) |
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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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const struct { |
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struct in6_addr saddr; |
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struct in6_addr daddr; |
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__be16 sport; |
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__be16 dport; |
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} __aligned(SIPHASH_ALIGNMENT) combined = { |
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.saddr = *(struct in6_addr *)saddr, |
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.daddr = *(struct in6_addr *)daddr, |
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.sport = sport, |
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.dport = dport |
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}; |
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u64 seq; |
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net_secret_init(); |
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seq = siphash(&combined, offsetofend(typeof(combined), dport), |
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&net_secret); |
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seq += ktime_get_real_ns(); |
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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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