net/xfrm/compat: Copy xfrm_spdattr_type_t atributes

The attribute-translator has to take in mind maxtype, that is
xfrm_link::nla_max. When it is set, attributes are not of xfrm_attr_type_t.
Currently, they can be only XFRMA_SPD_MAX (message XFRM_MSG_NEWSPDINFO),
their UABI is the same for 64/32-bit, so just copy them.

Thanks to YueHaibing for reporting this:
In xfrm_user_rcv_msg_compat() if maxtype is not zero and less than
XFRMA_MAX, nlmsg_parse_deprecated() do not initialize attrs array fully.
xfrm_xlate32() will access uninit 'attrs[i]' while iterating all attrs
array.

KASAN: probably user-memory-access in range [0x0000000041b58ab0-0x0000000041b58ab7]
CPU: 0 PID: 15799 Comm: syz-executor.2 Tainted: G        W         5.14.0-rc1-syzkaller #0
RIP: 0010:nla_type include/net/netlink.h:1130 [inline]
RIP: 0010:xfrm_xlate32_attr net/xfrm/xfrm_compat.c:410 [inline]
RIP: 0010:xfrm_xlate32 net/xfrm/xfrm_compat.c:532 [inline]
RIP: 0010:xfrm_user_rcv_msg_compat+0x5e5/0x1070 net/xfrm/xfrm_compat.c:577
[...]
Call Trace:
 xfrm_user_rcv_msg+0x556/0x8b0 net/xfrm/xfrm_user.c:2774
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2824
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:702 [inline]

Fixes: 5106f4a8acff ("xfrm/compat: Add 32=>64-bit messages translator")
Cc: <stable@kernel.org>
Reported-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/net/xfrm/xfrm_compat.c b/net/xfrm/xfrm_compat.c
index a20aec9..2bf2693 100644 (file)
--- a/net/xfrm/xfrm_compat.c
+++ b/net/xfrm/xfrm_compat.c
@@ -298,8 +298,16 @@ static int xfrm_xlate64(struct sk_buff *dst, const struct nlmsghdr *nlh_src)
        len = nlmsg_attrlen(nlh_src, xfrm_msg_min[type]);
 
        nla_for_each_attr(nla, attrs, len, remaining) {
-               int err = xfrm_xlate64_attr(dst, nla);
+               int err;
 
+               switch (type) {
+               case XFRM_MSG_NEWSPDINFO:
+                       err = xfrm_nla_cpy(dst, nla, nla_len(nla));
+                       break;
+               default:
+                       err = xfrm_xlate64_attr(dst, nla);
+                       break;
+               }
                if (err)
                        return err;
        }
@@ -341,7 +349,8 @@ static int xfrm_alloc_compat(struct sk_buff *skb, const struct nlmsghdr *nlh_src
 
 /* Calculates len of translated 64-bit message. */
 static size_t xfrm_user_rcv_calculate_len64(const struct nlmsghdr *src,
-                                           struct nlattr *attrs[XFRMA_MAX+1])
+                                           struct nlattr *attrs[XFRMA_MAX + 1],
+                                           int maxtype)
 {
        size_t len = nlmsg_len(src);
 
@@ -358,10 +367,20 @@ static size_t xfrm_user_rcv_calculate_len64(const struct nlmsghdr *src,
        case XFRM_MSG_POLEXPIRE:
                len += 8;
                break;
+       case XFRM_MSG_NEWSPDINFO:
+               /* attirbutes are xfrm_spdattr_type_t, not xfrm_attr_type_t */
+               return len;
        default:
                break;
        }
 
+       /* Unexpected for anything, but XFRM_MSG_NEWSPDINFO, please
+        * correct both 64=>32-bit and 32=>64-bit translators to copy
+        * new attributes.
+        */
+       if (WARN_ON_ONCE(maxtype))
+               return len;
+
        if (attrs[XFRMA_SA])
                len += 4;
        if (attrs[XFRMA_POLICY])
@@ -440,7 +459,8 @@ static int xfrm_xlate32_attr(void *dst, const struct nlattr *nla,
 
 static int xfrm_xlate32(struct nlmsghdr *dst, const struct nlmsghdr *src,
                        struct nlattr *attrs[XFRMA_MAX+1],
-                       size_t size, u8 type, struct netlink_ext_ack *extack)
+                       size_t size, u8 type, int maxtype,
+                       struct netlink_ext_ack *extack)
 {
        size_t pos;
        int i;
@@ -520,6 +540,25 @@ static int xfrm_xlate32(struct nlmsghdr *dst, const struct nlmsghdr *src,
        }
        pos = dst->nlmsg_len;
 
+       if (maxtype) {
+               /* attirbutes are xfrm_spdattr_type_t, not xfrm_attr_type_t */
+               WARN_ON_ONCE(src->nlmsg_type != XFRM_MSG_NEWSPDINFO);
+
+               for (i = 1; i <= maxtype; i++) {
+                       int err;
+
+                       if (!attrs[i])
+                               continue;
+
+                       /* just copy - no need for translation */
+                       err = xfrm_attr_cpy32(dst, &pos, attrs[i], size,
+                                       nla_len(attrs[i]), nla_len(attrs[i]));
+                       if (err)
+                               return err;
+               }
+               return 0;
+       }
+
        for (i = 1; i < XFRMA_MAX + 1; i++) {
                int err;
 
@@ -564,7 +603,7 @@ static struct nlmsghdr *xfrm_user_rcv_msg_compat(const struct nlmsghdr *h32,
        if (err < 0)
                return ERR_PTR(err);
 
-       len = xfrm_user_rcv_calculate_len64(h32, attrs);
+       len = xfrm_user_rcv_calculate_len64(h32, attrs, maxtype);
        /* The message doesn't need translation */
        if (len == nlmsg_len(h32))
                return NULL;
@@ -574,7 +613,7 @@ static struct nlmsghdr *xfrm_user_rcv_msg_compat(const struct nlmsghdr *h32,
        if (!h64)
                return ERR_PTR(-ENOMEM);
 
-       err = xfrm_xlate32(h64, h32, attrs, len, type, extack);
+       err = xfrm_xlate32(h64, h32, attrs, len, type, maxtype, extack);
        if (err < 0) {
                kvfree(h64);
                return ERR_PTR(err);