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net/tcp-ao: Use stack-allocated MAC and traffic_key buffers

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Now that the maximum MAC and traffic key lengths are statically-known
small values, allocate MACs and traffic keys on the stack instead of
with kmalloc.  This eliminates multiple failure-prone GFP_ATOMIC
allocations.

Note that some cases such as tcp_ao_prepare_reset() are left unchanged
for now since they would require slightly wider changes.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20260427172727.9310-4-ebiggers@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Eric Biggers 2026-04-27 10:27:25 -07:00 committed by Paolo Abeni
parent 068f5a0095
commit 4816879989
2 changed files with 16 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
net/ipv4/tcp_ao.c
View File

@ -739,22 +739,15 @@ int tcp_v4_ao_synack_hash(char *ao_hash, struct tcp_ao_key *ao_key,
struct request_sock *req, const struct sk_buff *skb,
int hash_offset, u32 sne)
{
void *hash_buf = NULL;
u8 tkey_buf[TCP_AO_MAX_TRAFFIC_KEY_LEN];
int err;
hash_buf = kmalloc(tcp_ao_digest_size(ao_key), GFP_ATOMIC);
if (!hash_buf)
return -ENOMEM;
err = tcp_v4_ao_calc_key_rsk(ao_key, hash_buf, req);
err = tcp_v4_ao_calc_key_rsk(ao_key, tkey_buf, req);
if (err)
goto out;
return err;
err = tcp_ao_hash_skb(AF_INET, ao_hash, ao_key, req_to_sk(req), skb,
hash_buf, hash_offset, sne);
out:
kfree(hash_buf);
return err;
return tcp_ao_hash_skb(AF_INET, ao_hash, ao_key, req_to_sk(req), skb,
tkey_buf, hash_offset, sne);
}
struct tcp_ao_key *tcp_v4_ao_lookup_rsk(const struct sock *sk,
@ -869,9 +862,9 @@ int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
__u8 *hash_location)
{
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
u8 tkey_buf[TCP_AO_MAX_TRAFFIC_KEY_LEN];
struct tcp_sock *tp = tcp_sk(sk);
struct tcp_ao_info *ao;
void *tkey_buf = NULL;
u8 *traffic_key;
u32 sne;
@ -883,9 +876,6 @@ int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
if (!(tcb->tcp_flags & TCPHDR_ACK)) {
disn = 0;
tkey_buf = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC);
if (!tkey_buf)
return -ENOMEM;
traffic_key = tkey_buf;
} else {
disn = ao->risn;
@ -897,7 +887,6 @@ int tcp_ao_transmit_skb(struct sock *sk, struct sk_buff *skb,
ntohl(th->seq));
tp->af_specific->calc_ao_hash(hash_location, key, sk, skb, traffic_key,
hash_location - (u8 *)th, sne);
kfree(tkey_buf);
return 0;
}
@ -963,7 +952,7 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
{
const struct tcphdr *th = tcp_hdr(skb);
u8 maclen = tcp_ao_hdr_maclen(aoh);
void *hash_buf = NULL;
u8 hash_buf[TCP_AO_MAX_MAC_LEN];
if (maclen != tcp_ao_maclen(key)) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOBAD);
@ -974,10 +963,6 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
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);
@ -987,13 +972,11 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
atomic64_inc(&key->pkt_bad);
trace_tcp_ao_mismatch(sk, skb, aoh->keyid,
aoh->rnext_keyid, maclen);
kfree(hash_buf);
return SKB_DROP_REASON_TCP_AOFAILURE;
}
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOGOOD);
atomic64_inc(&info->counters.pkt_good);
atomic64_inc(&key->pkt_good);
kfree(hash_buf);
return SKB_NOT_DROPPED_YET;
}
@ -1002,11 +985,11 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
unsigned short int family, const struct request_sock *req,
int l3index, const struct tcp_ao_hdr *aoh)
{
u8 tkey_buf[TCP_AO_MAX_TRAFFIC_KEY_LEN];
const struct tcphdr *th = tcp_hdr(skb);
u8 maclen = tcp_ao_hdr_maclen(aoh);
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;
@ -1114,14 +1097,9 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
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, l3index);
kfree(traffic_key);
return ret;
tcp_ao_calc_key_skb(key, tkey_buf, skb, sisn, disn, family);
return tcp_ao_verify_hash(sk, skb, family, info, aoh, key,
tkey_buf, phash, sne, l3index);
key_not_found:
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOKEYNOTFOUND);

17
net/ipv6/tcp_ao.c
View File

@ -138,20 +138,13 @@ int tcp_v6_ao_synack_hash(char *ao_hash, struct tcp_ao_key *ao_key,
struct request_sock *req, const struct sk_buff *skb,
int hash_offset, u32 sne)
{
void *hash_buf = NULL;
u8 tkey_buf[TCP_AO_MAX_TRAFFIC_KEY_LEN];
int err;
hash_buf = kmalloc(tcp_ao_digest_size(ao_key), GFP_ATOMIC);
if (!hash_buf)
return -ENOMEM;
err = tcp_v6_ao_calc_key_rsk(ao_key, hash_buf, req);
err = tcp_v6_ao_calc_key_rsk(ao_key, tkey_buf, req);
if (err)
goto out;
return err;
err = tcp_ao_hash_skb(AF_INET6, ao_hash, ao_key, req_to_sk(req), skb,
hash_buf, hash_offset, sne);
out:
kfree(hash_buf);
return err;
return tcp_ao_hash_skb(AF_INET6, ao_hash, ao_key, req_to_sk(req), skb,
tkey_buf, hash_offset, sne);
}