[PATCH net] net: af_key: zero aligned sockaddr tail in PF_KEY exports

[Zhengchuan Liang <zcliangcn@gmail.com>]

PF_KEY export paths use `pfkey_sockaddr_size()` when reserving sockaddr
payload space, so IPv6 addresses occupy 32 bytes on the wire. However,
`pfkey_sockaddr_fill()` initializes only the first 28 bytes of
`struct sockaddr_in6`, leaving the final 4 aligned bytes uninitialized.

Not every PF_KEY message is affected. The state and policy dump builders
already zero the whole message buffer before filling the sockaddr
payloads. Keep the fix to the export paths that still append aligned
sockaddr payloads with plain `skb_put()`:

  - `SADB_ACQUIRE`
  - `SADB_X_NAT_T_NEW_MAPPING`
  - `SADB_X_MIGRATE`

Fix those paths by clearing only the aligned sockaddr tail after
`pfkey_sockaddr_fill()`.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Fixes: 08de61beab8a ("[PFKEYV2]: Extension for dynamic update of endpoint address(es)")
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Co-developed-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Yuan Tan <yuantan098@gmail.com>
Suggested-by: Xin Liu <bird@lzu.edu.cn>
Tested-by: Xiao Liu <lx24@stu.ynu.edu.cn>
Signed-off-by: Zhengchuan Liang <zcliangcn@gmail.com>
---
 net/key/af_key.c | 52 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 34 insertions(+), 18 deletions(-)

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 0756bac62f7c0..f3f8f3c15a940 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -757,6 +757,22 @@ static unsigned int pfkey_sockaddr_fill(const xfrm_address_t *xaddr, __be16 port
 	return 0;
 }
 
+static unsigned int pfkey_sockaddr_fill_zero_tail(const xfrm_address_t *xaddr,
+						  __be16 port,
+						  struct sockaddr *sa,
+						  unsigned short family)
+{
+	unsigned int prefixlen;
+	int sockaddr_len = pfkey_sockaddr_len(family);
+	int sockaddr_size = pfkey_sockaddr_size(family);
+
+	prefixlen = pfkey_sockaddr_fill(xaddr, port, sa, family);
+	if (sockaddr_size > sockaddr_len)
+		memset((u8 *)sa + sockaddr_len, 0, sockaddr_size - sockaddr_len);
+
+	return prefixlen;
+}
+
 static struct sk_buff *__pfkey_xfrm_state2msg(const struct xfrm_state *x,
 					      int add_keys, int hsc)
 {
@@ -3206,9 +3222,9 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
 	addr->sadb_address_proto = 0;
 	addr->sadb_address_reserved = 0;
 	addr->sadb_address_prefixlen =
-		pfkey_sockaddr_fill(&x->props.saddr, 0,
-				    (struct sockaddr *) (addr + 1),
-				    x->props.family);
+		pfkey_sockaddr_fill_zero_tail(&x->props.saddr, 0,
+					      (struct sockaddr *)(addr + 1),
+					      x->props.family);
 	if (!addr->sadb_address_prefixlen)
 		BUG();
 
@@ -3221,9 +3237,9 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
 	addr->sadb_address_proto = 0;
 	addr->sadb_address_reserved = 0;
 	addr->sadb_address_prefixlen =
-		pfkey_sockaddr_fill(&x->id.daddr, 0,
-				    (struct sockaddr *) (addr + 1),
-				    x->props.family);
+		pfkey_sockaddr_fill_zero_tail(&x->id.daddr, 0,
+					      (struct sockaddr *)(addr + 1),
+					      x->props.family);
 	if (!addr->sadb_address_prefixlen)
 		BUG();
 
@@ -3421,9 +3437,9 @@ static int pfkey_send_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr,
 	addr->sadb_address_proto = 0;
 	addr->sadb_address_reserved = 0;
 	addr->sadb_address_prefixlen =
-		pfkey_sockaddr_fill(&x->props.saddr, 0,
-				    (struct sockaddr *) (addr + 1),
-				    x->props.family);
+		pfkey_sockaddr_fill_zero_tail(&x->props.saddr, 0,
+					      (struct sockaddr *)(addr + 1),
+					      x->props.family);
 	if (!addr->sadb_address_prefixlen)
 		BUG();
 
@@ -3443,9 +3459,9 @@ static int pfkey_send_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr,
 	addr->sadb_address_proto = 0;
 	addr->sadb_address_reserved = 0;
 	addr->sadb_address_prefixlen =
-		pfkey_sockaddr_fill(ipaddr, 0,
-				    (struct sockaddr *) (addr + 1),
-				    x->props.family);
+		pfkey_sockaddr_fill_zero_tail(ipaddr, 0,
+					      (struct sockaddr *)(addr + 1),
+					      x->props.family);
 	if (!addr->sadb_address_prefixlen)
 		BUG();
 
@@ -3474,15 +3490,15 @@ static int set_sadb_address(struct sk_buff *skb, int sasize, int type,
 	switch (type) {
 	case SADB_EXT_ADDRESS_SRC:
 		addr->sadb_address_prefixlen = sel->prefixlen_s;
-		pfkey_sockaddr_fill(&sel->saddr, 0,
-				    (struct sockaddr *)(addr + 1),
-				    sel->family);
+		pfkey_sockaddr_fill_zero_tail(&sel->saddr, 0,
+					      (struct sockaddr *)(addr + 1),
+					      sel->family);
 		break;
 	case SADB_EXT_ADDRESS_DST:
 		addr->sadb_address_prefixlen = sel->prefixlen_d;
-		pfkey_sockaddr_fill(&sel->daddr, 0,
-				    (struct sockaddr *)(addr + 1),
-				    sel->family);
+		pfkey_sockaddr_fill_zero_tail(&sel->daddr, 0,
+					      (struct sockaddr *)(addr + 1),
+					      sel->family);
 		break;
 	default:
 		return -EINVAL;
-- 
2.43.0