mirror of
https://github.com/torvalds/linux
synced 2024-07-23 03:29:48 +00:00
net/tcp: Verify inbound TCP-AO signed segments
Now there is a common function to verify signature on TCP segments:
tcp_inbound_hash(). It has checks for all possible cross-interactions
with MD5 signs as well as with unsigned segments.
The rules from RFC5925 are:
(1) Any TCP segment can have at max only one signature.
(2) TCP connections can't switch between using TCP-MD5 and TCP-AO.
(3) TCP-AO connections can't stop using AO, as well as unsigned
connections can't suddenly start using AO.
Co-developed-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Dmitry Safonov
David S. Miller
parent
9427c6aa3e
commit
0a3a809089
|
|
@ -24,6 +24,10 @@
|
|||
FN(TCP_MD5NOTFOUND) \
|
||||
FN(TCP_MD5UNEXPECTED) \
|
||||
FN(TCP_MD5FAILURE) \
|
||||
FN(TCP_AONOTFOUND) \
|
||||
FN(TCP_AOUNEXPECTED) \
|
||||
FN(TCP_AOKEYNOTFOUND) \
|
||||
FN(TCP_AOFAILURE) \
|
||||
FN(SOCKET_BACKLOG) \
|
||||
FN(TCP_FLAGS) \
|
||||
FN(TCP_ZEROWINDOW) \
|
||||
|
|
@ -163,6 +167,19 @@ enum skb_drop_reason {
|
|||
* to LINUX_MIB_TCPMD5FAILURE
|
||||
*/
|
||||
SKB_DROP_REASON_TCP_MD5FAILURE,
|
||||
/**
|
||||
* @SKB_DROP_REASON_TCP_AONOTFOUND: no TCP-AO hash and one was expected
|
||||
*/
|
||||
SKB_DROP_REASON_TCP_AONOTFOUND,
|
||||
/**
|
||||
* @SKB_DROP_REASON_TCP_AOUNEXPECTED: TCP-AO hash is present and it
|
||||
* was not expected.
|
||||
*/
|
||||
SKB_DROP_REASON_TCP_AOUNEXPECTED,
|
||||
/** @SKB_DROP_REASON_TCP_AOKEYNOTFOUND: TCP-AO key is unknown */
|
||||
SKB_DROP_REASON_TCP_AOKEYNOTFOUND,
|
||||
/** @SKB_DROP_REASON_TCP_AOFAILURE: TCP-AO hash is wrong */
|
||||
SKB_DROP_REASON_TCP_AOFAILURE,
|
||||
/**
|
||||
* @SKB_DROP_REASON_SOCKET_BACKLOG: failed to add skb to socket backlog (
|
||||
* see LINUX_MIB_TCPBACKLOGDROP)
|
||||
|
|
|
|||
|
|
@ -1809,7 +1809,7 @@ tcp_md5_do_lookup_any_l3index(const struct sock *sk,
|
|||
enum skb_drop_reason
|
||||
tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
|
||||
const void *saddr, const void *daddr,
|
||||
int family, int dif, int sdif);
|
||||
int family, int l3index, const __u8 *hash_location);
|
||||
|
||||
|
||||
#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
|
||||
|
|
@ -1831,7 +1831,7 @@ tcp_md5_do_lookup_any_l3index(const struct sock *sk,
|
|||
static inline enum skb_drop_reason
|
||||
tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
|
||||
const void *saddr, const void *daddr,
|
||||
int family, int dif, int sdif)
|
||||
int family, int l3index, const __u8 *hash_location)
|
||||
{
|
||||
return SKB_NOT_DROPPED_YET;
|
||||
}
|
||||
|
|
@ -2730,4 +2730,53 @@ static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
|
|||
return false;
|
||||
}
|
||||
|
||||
/* Called with rcu_read_lock() */
|
||||
static inline enum skb_drop_reason
|
||||
tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
|
||||
const struct sk_buff *skb,
|
||||
const void *saddr, const void *daddr,
|
||||
int family, int dif, int sdif)
|
||||
{
|
||||
const struct tcphdr *th = tcp_hdr(skb);
|
||||
const struct tcp_ao_hdr *aoh;
|
||||
const __u8 *md5_location;
|
||||
int l3index;
|
||||
|
||||
/* Invalid option or two times meet any of auth options */
|
||||
if (tcp_parse_auth_options(th, &md5_location, &aoh))
|
||||
return SKB_DROP_REASON_TCP_AUTH_HDR;
|
||||
|
||||
if (req) {
|
||||
if (tcp_rsk_used_ao(req) != !!aoh)
|
||||
return SKB_DROP_REASON_TCP_AOFAILURE;
|
||||
}
|
||||
|
||||
/* sdif set, means packet ingressed via a device
|
||||
* in an L3 domain and dif is set to the l3mdev
|
||||
*/
|
||||
l3index = sdif ? dif : 0;
|
||||
|
||||
/* Fast path: unsigned segments */
|
||||
if (likely(!md5_location && !aoh)) {
|
||||
/* Drop if there's TCP-MD5 or TCP-AO key with any rcvid/sndid
|
||||
* for the remote peer. On TCP-AO established connection
|
||||
* the last key is impossible to remove, so there's
|
||||
* always at least one current_key.
|
||||
*/
|
||||
if (tcp_ao_required(sk, saddr, family))
|
||||
return SKB_DROP_REASON_TCP_AONOTFOUND;
|
||||
if (unlikely(tcp_md5_do_lookup(sk, l3index, saddr, family))) {
|
||||
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
|
||||
return SKB_DROP_REASON_TCP_MD5NOTFOUND;
|
||||
}
|
||||
return SKB_NOT_DROPPED_YET;
|
||||
}
|
||||
|
||||
if (aoh)
|
||||
return tcp_inbound_ao_hash(sk, skb, family, req, aoh);
|
||||
|
||||
return tcp_inbound_md5_hash(sk, skb, saddr, daddr, family,
|
||||
l3index, md5_location);
|
||||
}
|
||||
|
||||
#endif /* _TCP_H */
|
||||
|
|
|
|||
|
|
@ -111,6 +111,9 @@ struct tcp6_ao_context {
|
|||
};
|
||||
|
||||
struct tcp_sigpool;
|
||||
#define TCP_AO_ESTABLISHED (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | \
|
||||
TCPF_CLOSE | TCPF_CLOSE_WAIT | \
|
||||
TCPF_LAST_ACK | TCPF_CLOSING)
|
||||
|
||||
int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
|
||||
struct tcp_ao_key *key, struct tcphdr *th,
|
||||
|
|
@ -130,6 +133,10 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
|
|||
unsigned int len, struct tcp_sigpool *hp);
|
||||
void tcp_ao_destroy_sock(struct sock *sk, bool twsk);
|
||||
void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp);
|
||||
enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
|
||||
const struct sk_buff *skb, unsigned short int family,
|
||||
const struct request_sock *req,
|
||||
const struct tcp_ao_hdr *aoh);
|
||||
struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
|
||||
const union tcp_ao_addr *addr,
|
||||
int family, int sndid, int rcvid);
|
||||
|
|
@ -208,6 +215,13 @@ static inline void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
|
|||
{
|
||||
}
|
||||
|
||||
static inline enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
|
||||
const struct sk_buff *skb, unsigned short int family,
|
||||
const struct request_sock *req, const struct tcp_ao_hdr *aoh)
|
||||
{
|
||||
return SKB_NOT_DROPPED_YET;
|
||||
}
|
||||
|
||||
static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
|
||||
const union tcp_ao_addr *addr, int family, int sndid, int rcvid)
|
||||
{
|
||||
|
|
|
|||
|
|
@ -4375,42 +4375,23 @@ EXPORT_SYMBOL(tcp_md5_hash_key);
|
|||
enum skb_drop_reason
|
||||
tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
|
||||
const void *saddr, const void *daddr,
|
||||
int family, int dif, int sdif)
|
||||
int family, int l3index, const __u8 *hash_location)
|
||||
{
|
||||
/*
|
||||
* This gets called for each TCP segment that arrives
|
||||
* so we want to be efficient.
|
||||
/* This gets called for each TCP segment that has TCP-MD5 option.
|
||||
* We have 3 drop cases:
|
||||
* o No MD5 hash and one expected.
|
||||
* o MD5 hash and we're not expecting one.
|
||||
* o MD5 hash and its wrong.
|
||||
*/
|
||||
const __u8 *hash_location = NULL;
|
||||
struct tcp_md5sig_key *hash_expected;
|
||||
const struct tcphdr *th = tcp_hdr(skb);
|
||||
const struct tcp_sock *tp = tcp_sk(sk);
|
||||
int genhash, l3index;
|
||||
struct tcp_md5sig_key *key;
|
||||
u8 newhash[16];
|
||||
int genhash;
|
||||
|
||||
/* sdif set, means packet ingressed via a device
|
||||
* in an L3 domain and dif is set to the l3mdev
|
||||
*/
|
||||
l3index = sdif ? dif : 0;
|
||||
key = tcp_md5_do_lookup(sk, l3index, saddr, family);
|
||||
|
||||
hash_expected = tcp_md5_do_lookup(sk, l3index, saddr, family);
|
||||
if (tcp_parse_auth_options(th, &hash_location, NULL))
|
||||
return SKB_DROP_REASON_TCP_AUTH_HDR;
|
||||
|
||||
/* We've parsed the options - do we have a hash? */
|
||||
if (!hash_expected && !hash_location)
|
||||
return SKB_NOT_DROPPED_YET;
|
||||
|
||||
if (hash_expected && !hash_location) {
|
||||
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
|
||||
return SKB_DROP_REASON_TCP_MD5NOTFOUND;
|
||||
}
|
||||
|
||||
if (!hash_expected && hash_location) {
|
||||
if (!key && hash_location) {
|
||||
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
|
||||
return SKB_DROP_REASON_TCP_MD5UNEXPECTED;
|
||||
}
|
||||
|
|
@ -4420,14 +4401,10 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
|
|||
* IPv4-mapped case.
|
||||
*/
|
||||
if (family == AF_INET)
|
||||
genhash = tcp_v4_md5_hash_skb(newhash,
|
||||
hash_expected,
|
||||
NULL, skb);
|
||||
genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
|
||||
else
|
||||
genhash = tp->af_specific->calc_md5_hash(newhash,
|
||||
hash_expected,
|
||||
genhash = tp->af_specific->calc_md5_hash(newhash, key,
|
||||
NULL, skb);
|
||||
|
||||
if (genhash || memcmp(hash_location, newhash, 16) != 0) {
|
||||
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
|
||||
if (family == AF_INET) {
|
||||
|
|
|
|||
|
|
@ -761,6 +761,148 @@ void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
|
|||
treq->maclen = tcp_ao_maclen(key);
|
||||
}
|
||||
|
||||
static enum skb_drop_reason
|
||||
tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
|
||||
unsigned short int family, struct tcp_ao_info *info,
|
||||
const struct tcp_ao_hdr *aoh, struct tcp_ao_key *key,
|
||||
u8 *traffic_key, u8 *phash, u32 sne)
|
||||
{
|
||||
u8 maclen = aoh->length - sizeof(struct tcp_ao_hdr);
|
||||
const struct tcphdr *th = tcp_hdr(skb);
|
||||
void *hash_buf = NULL;
|
||||
|
||||
if (maclen != tcp_ao_maclen(key))
|
||||
return SKB_DROP_REASON_TCP_AOFAILURE;
|
||||
|
||||
hash_buf = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC);
|
||||
if (!hash_buf)
|
||||
return SKB_DROP_REASON_NOT_SPECIFIED;
|
||||
|
||||
/* XXX: make it per-AF callback? */
|
||||
tcp_ao_hash_skb(family, hash_buf, key, sk, skb, traffic_key,
|
||||
(phash - (u8 *)th), sne);
|
||||
if (memcmp(phash, hash_buf, maclen)) {
|
||||
kfree(hash_buf);
|
||||
return SKB_DROP_REASON_TCP_AOFAILURE;
|
||||
}
|
||||
kfree(hash_buf);
|
||||
return SKB_NOT_DROPPED_YET;
|
||||
}
|
||||
|
||||
enum skb_drop_reason
|
||||
tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
|
||||
unsigned short int family, const struct request_sock *req,
|
||||
const struct tcp_ao_hdr *aoh)
|
||||
{
|
||||
const struct tcphdr *th = tcp_hdr(skb);
|
||||
u8 *phash = (u8 *)(aoh + 1); /* hash goes just after the header */
|
||||
struct tcp_ao_info *info;
|
||||
enum skb_drop_reason ret;
|
||||
struct tcp_ao_key *key;
|
||||
__be32 sisn, disn;
|
||||
u8 *traffic_key;
|
||||
u32 sne = 0;
|
||||
|
||||
info = rcu_dereference(tcp_sk(sk)->ao_info);
|
||||
if (!info)
|
||||
return SKB_DROP_REASON_TCP_AOUNEXPECTED;
|
||||
|
||||
if (unlikely(th->syn)) {
|
||||
sisn = th->seq;
|
||||
disn = 0;
|
||||
}
|
||||
|
||||
/* Fast-path */
|
||||
if (likely((1 << sk->sk_state) & TCP_AO_ESTABLISHED)) {
|
||||
enum skb_drop_reason err;
|
||||
struct tcp_ao_key *current_key;
|
||||
|
||||
/* Check if this socket's rnext_key matches the keyid in the
|
||||
* packet. If not we lookup the key based on the keyid
|
||||
* matching the rcvid in the mkt.
|
||||
*/
|
||||
key = READ_ONCE(info->rnext_key);
|
||||
if (key->rcvid != aoh->keyid) {
|
||||
key = tcp_ao_established_key(info, -1, aoh->keyid);
|
||||
if (!key)
|
||||
goto key_not_found;
|
||||
}
|
||||
|
||||
/* Delayed retransmitted SYN */
|
||||
if (unlikely(th->syn && !th->ack))
|
||||
goto verify_hash;
|
||||
|
||||
sne = 0;
|
||||
/* Established socket, traffic key are cached */
|
||||
traffic_key = rcv_other_key(key);
|
||||
err = tcp_ao_verify_hash(sk, skb, family, info, aoh, key,
|
||||
traffic_key, phash, sne);
|
||||
if (err)
|
||||
return err;
|
||||
current_key = READ_ONCE(info->current_key);
|
||||
/* Key rotation: the peer asks us to use new key (RNext) */
|
||||
if (unlikely(aoh->rnext_keyid != current_key->sndid)) {
|
||||
/* If the key is not found we do nothing. */
|
||||
key = tcp_ao_established_key(info, aoh->rnext_keyid, -1);
|
||||
if (key)
|
||||
/* pairs with tcp_ao_del_cmd */
|
||||
WRITE_ONCE(info->current_key, key);
|
||||
}
|
||||
return SKB_NOT_DROPPED_YET;
|
||||
}
|
||||
|
||||
/* Lookup key based on peer address and keyid.
|
||||
* current_key and rnext_key must not be used on tcp listen
|
||||
* sockets as otherwise:
|
||||
* - request sockets would race on those key pointers
|
||||
* - tcp_ao_del_cmd() allows async key removal
|
||||
*/
|
||||
key = tcp_ao_inbound_lookup(family, sk, skb, -1, aoh->keyid);
|
||||
if (!key)
|
||||
goto key_not_found;
|
||||
|
||||
if (th->syn && !th->ack)
|
||||
goto verify_hash;
|
||||
|
||||
if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV)) {
|
||||
/* Make the initial syn the likely case here */
|
||||
if (unlikely(req)) {
|
||||
sne = 0;
|
||||
sisn = htonl(tcp_rsk(req)->rcv_isn);
|
||||
disn = htonl(tcp_rsk(req)->snt_isn);
|
||||
} else if (unlikely(th->ack && !th->syn)) {
|
||||
/* Possible syncookie packet */
|
||||
sisn = htonl(ntohl(th->seq) - 1);
|
||||
disn = htonl(ntohl(th->ack_seq) - 1);
|
||||
sne = 0;
|
||||
} else if (unlikely(!th->syn)) {
|
||||
/* no way to figure out initial sisn/disn - drop */
|
||||
return SKB_DROP_REASON_TCP_FLAGS;
|
||||
}
|
||||
} else if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
|
||||
disn = info->lisn;
|
||||
if (th->syn || th->rst)
|
||||
sisn = th->seq;
|
||||
else
|
||||
sisn = info->risn;
|
||||
} else {
|
||||
WARN_ONCE(1, "TCP-AO: Unexpected sk_state %d", sk->sk_state);
|
||||
return SKB_DROP_REASON_TCP_AOFAILURE;
|
||||
}
|
||||
verify_hash:
|
||||
traffic_key = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC);
|
||||
if (!traffic_key)
|
||||
return SKB_DROP_REASON_NOT_SPECIFIED;
|
||||
tcp_ao_calc_key_skb(key, traffic_key, skb, sisn, disn, family);
|
||||
ret = tcp_ao_verify_hash(sk, skb, family, info, aoh, key,
|
||||
traffic_key, phash, sne);
|
||||
kfree(traffic_key);
|
||||
return ret;
|
||||
|
||||
key_not_found:
|
||||
return SKB_DROP_REASON_TCP_AOKEYNOTFOUND;
|
||||
}
|
||||
|
||||
static int tcp_ao_cache_traffic_keys(const struct sock *sk,
|
||||
struct tcp_ao_info *ao,
|
||||
struct tcp_ao_key *ao_key)
|
||||
|
|
|
|||
|
|
@ -2204,9 +2204,9 @@ int tcp_v4_rcv(struct sk_buff *skb)
|
|||
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
|
||||
drop_reason = SKB_DROP_REASON_XFRM_POLICY;
|
||||
else
|
||||
drop_reason = tcp_inbound_md5_hash(sk, skb,
|
||||
&iph->saddr, &iph->daddr,
|
||||
AF_INET, dif, sdif);
|
||||
drop_reason = tcp_inbound_hash(sk, req, skb,
|
||||
&iph->saddr, &iph->daddr,
|
||||
AF_INET, dif, sdif);
|
||||
if (unlikely(drop_reason)) {
|
||||
sk_drops_add(sk, skb);
|
||||
reqsk_put(req);
|
||||
|
|
@ -2283,8 +2283,8 @@ int tcp_v4_rcv(struct sk_buff *skb)
|
|||
goto discard_and_relse;
|
||||
}
|
||||
|
||||
drop_reason = tcp_inbound_md5_hash(sk, skb, &iph->saddr,
|
||||
&iph->daddr, AF_INET, dif, sdif);
|
||||
drop_reason = tcp_inbound_hash(sk, NULL, skb, &iph->saddr, &iph->daddr,
|
||||
AF_INET, dif, sdif);
|
||||
if (drop_reason)
|
||||
goto discard_and_relse;
|
||||
|
||||
|
|
|
|||
|
|
@ -53,11 +53,12 @@ int tcp_v6_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
|
|||
const struct sk_buff *skb,
|
||||
__be32 sisn, __be32 disn)
|
||||
{
|
||||
const struct ipv6hdr *iph = ipv6_hdr(skb);
|
||||
const struct tcphdr *th = tcp_hdr(skb);
|
||||
const struct ipv6hdr *iph = ipv6_hdr(skb);
|
||||
const struct tcphdr *th = tcp_hdr(skb);
|
||||
|
||||
return tcp_v6_ao_calc_key(mkt, key, &iph->saddr, &iph->daddr,
|
||||
th->source, th->dest, sisn, disn);
|
||||
return tcp_v6_ao_calc_key(mkt, key, &iph->saddr,
|
||||
&iph->daddr, th->source,
|
||||
th->dest, sisn, disn);
|
||||
}
|
||||
|
||||
int tcp_v6_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,
|
||||
|
|
|
|||
|
|
@ -1785,9 +1785,9 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
|
|||
if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
|
||||
drop_reason = SKB_DROP_REASON_XFRM_POLICY;
|
||||
else
|
||||
drop_reason = tcp_inbound_md5_hash(sk, skb,
|
||||
&hdr->saddr, &hdr->daddr,
|
||||
AF_INET6, dif, sdif);
|
||||
drop_reason = tcp_inbound_hash(sk, req, skb,
|
||||
&hdr->saddr, &hdr->daddr,
|
||||
AF_INET6, dif, sdif);
|
||||
if (drop_reason) {
|
||||
sk_drops_add(sk, skb);
|
||||
reqsk_put(req);
|
||||
|
|
@ -1861,8 +1861,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
|
|||
goto discard_and_relse;
|
||||
}
|
||||
|
||||
drop_reason = tcp_inbound_md5_hash(sk, skb, &hdr->saddr, &hdr->daddr,
|
||||
AF_INET6, dif, sdif);
|
||||
drop_reason = tcp_inbound_hash(sk, NULL, skb, &hdr->saddr, &hdr->daddr,
|
||||
AF_INET6, dif, sdif);
|
||||
if (drop_reason)
|
||||
goto discard_and_relse;
|
||||
|
||||
|
|
@ -2089,6 +2089,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific = {
|
|||
.ao_lookup = tcp_v6_ao_lookup,
|
||||
.calc_ao_hash = tcp_v4_ao_hash_skb,
|
||||
.ao_parse = tcp_v6_parse_ao,
|
||||
.ao_calc_key_sk = tcp_v4_ao_calc_key_sk,
|
||||
#endif
|
||||
};
|
||||
#endif
|
||||
|
|
|
|||
Loading…
Reference in a new issue