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Commit 7dcade39 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'net_get_random_once' 



Hannes Frederic Sowa says:

====================
This series implements support for delaying the initialization of secret
keys, e.g. used for hashing, for as long as possible. This functionality
is implemented by a new macro, net_get_random_bytes.

I already used it to protect the socket hashes, the syncookie secret
(most important) and the tcp_fastopen secrets.

Changelog:
v2) Use static_keys in net_get_random_once to have as minimal impact to
    the fast-path as possible.
v3) added patch "static_key: WARN on usage before jump_label_init was called":
    Patch "x86/jump_label: expect default_nop if static_key gets enabled
    on boot-up" relaxes the checks for using static_key primitives before
    jump_label_init. So tighten them first.
v4) Update changelog on the patch "static_key: WARN on usage before
    jump_label_init was called"

Included patches:
 ipv4: split inet_ehashfn to hash functions per compilation unit
 ipv6: split inet6_ehashfn to hash functions per compilation unit
 static_key: WARN on usage before jump_label_init was called
 x86/jump_label: expect default_nop if static_key gets enabled on boot-up
 net: introduce new macro net_get_random_once
 inet: split syncookie keys for ipv4 and ipv6 and initialize with net_get_random_once
 inet: convert inet_ehash_secret and ipv6_hash_secret to net_get_random_once
 tcp: switch tcp_fastopen key generation to net_get_random_once
 net: switch net_secret key generation to net_get_random_once
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 53481da3 e34c9a69

arch/x86/kernel/jump_label.c

+18 −7
Original line number Diff line number Diff line
@@ -42,15 +42,27 @@ static void __jump_label_transform(struct jump_entry *entry, 
				   int init)

{

	union jump_code_union code;

	const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };

	const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];



	if (type == JUMP_LABEL_ENABLE) {

		if (init) {

			/*

			 * Jump label is enabled for the first time.

			 * So we expect a default_nop...

			 */

			if (unlikely(memcmp((void *)entry->code, default_nop, 5)

				     != 0))

				bug_at((void *)entry->code, __LINE__);

		} else {

			/*

		 * We are enabling this jump label. If it is not a nop

		 * then something must have gone wrong.

			 * ...otherwise expect an ideal_nop. Otherwise

			 * something went horribly wrong.

			 */

		if (unlikely(memcmp((void *)entry->code, ideal_nop, 5) != 0))

			if (unlikely(memcmp((void *)entry->code, ideal_nop, 5)

				     != 0))

				bug_at((void *)entry->code, __LINE__);

		}



		code.jump = 0xe9;

		code.offset = entry->target -
@@ -63,7 +75,6 @@ static void __jump_label_transform(struct jump_entry *entry, 
		 * are converting the default nop to the ideal nop.

		 */

		if (init) {

			const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };

			if (unlikely(memcmp((void *)entry->code, default_nop, 5) != 0))

				bug_at((void *)entry->code, __LINE__);

		} else {

include/linux/jump_label.h

+10 −0
Original line number Diff line number Diff line
@@ -48,6 +48,13 @@ 


#include <linux/types.h>

#include <linux/compiler.h>

#include <linux/bug.h>



extern bool static_key_initialized;



#define STATIC_KEY_CHECK_USE() WARN(!static_key_initialized,		      \

				    "%s used before call to jump_label_init", \

				    __func__)



#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
@@ -128,6 +135,7 @@ struct static_key { 


static __always_inline void jump_label_init(void)

{

	static_key_initialized = true;

}



static __always_inline bool static_key_false(struct static_key *key)
@@ -146,11 +154,13 @@ static __always_inline bool static_key_true(struct static_key *key) 


static inline void static_key_slow_inc(struct static_key *key)

{

	STATIC_KEY_CHECK_USE();

	atomic_inc(&key->enabled);

}



static inline void static_key_slow_dec(struct static_key *key)

{

	STATIC_KEY_CHECK_USE();

	atomic_dec(&key->enabled);

}

include/linux/jump_label_ratelimit.h

+2 −0
Original line number Diff line number Diff line
@@ -23,12 +23,14 @@ struct static_key_deferred { 
};

static inline void static_key_slow_dec_deferred(struct static_key_deferred *key)

{

	STATIC_KEY_CHECK_USE();

	static_key_slow_dec(&key->key);

}

static inline void

jump_label_rate_limit(struct static_key_deferred *key,

		unsigned long rl)

{

	STATIC_KEY_CHECK_USE();

}

#endif	/* HAVE_JUMP_LABEL */

#endif	/* _LINUX_JUMP_LABEL_RATELIMIT_H */

include/linux/net.h

+25 −0
Original line number Diff line number Diff line
@@ -239,6 +239,31 @@ do { \ 
#define net_random()		prandom_u32()

#define net_srandom(seed)	prandom_seed((__force u32)(seed))



bool __net_get_random_once(void *buf, int nbytes, bool *done,

			   struct static_key *done_key);



#ifdef HAVE_JUMP_LABEL

#define ___NET_RANDOM_STATIC_KEY_INIT ((struct static_key) \

		{ .enabled = ATOMIC_INIT(0), .entries = (void *)1 })

#else /* !HAVE_JUMP_LABEL */

#define ___NET_RANDOM_STATIC_KEY_INIT STATIC_KEY_INIT_FALSE

#endif /* HAVE_JUMP_LABEL */



/* BE CAREFUL: this function is not interrupt safe */

#define net_get_random_once(buf, nbytes)				\

	({								\

		bool ___ret = false;					\

		static bool ___done = false;				\

		static struct static_key ___done_key =			\

			___NET_RANDOM_STATIC_KEY_INIT;			\

		if (!static_key_true(&___done_key))			\

			___ret = __net_get_random_once(buf,		\

						       nbytes,		\

						       &___done,	\

						       &___done_key);	\

		___ret;							\

	})



int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,

		   size_t num, size_t len);

int kernel_recvmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,

include/net/inet6_hashtables.h

+7 −21
Original line number Diff line number Diff line
@@ -28,28 +28,14 @@ 


struct inet_hashinfo;



static inline unsigned int inet6_ehashfn(struct net *net,

				const struct in6_addr *laddr, const u16 lport,

				const struct in6_addr *faddr, const __be16 fport)

static inline unsigned int __inet6_ehashfn(const u32 lhash,

				    const u16 lport,

				    const u32 fhash,

				    const __be16 fport,

				    const u32 initval)

{

	u32 ports = (((u32)lport) << 16) | (__force u32)fport;



	return jhash_3words((__force u32)laddr->s6_addr32[3],

			    ipv6_addr_jhash(faddr),

			    ports,

			    inet_ehash_secret + net_hash_mix(net));

}



static inline int inet6_sk_ehashfn(const struct sock *sk)

{

	const struct inet_sock *inet = inet_sk(sk);

	const struct in6_addr *laddr = &sk->sk_v6_rcv_saddr;

	const struct in6_addr *faddr = &sk->sk_v6_daddr;

	const __u16 lport = inet->inet_num;

	const __be16 fport = inet->inet_dport;

	struct net *net = sock_net(sk);



	return inet6_ehashfn(net, laddr, lport, faddr, fport);

	const u32 ports = (((u32)lport) << 16) | (__force u32)fport;

	return jhash_3words(lhash, fhash, ports, initval);

}



int __inet6_hash(struct sock *sk, struct inet_timewait_sock *twp);