xfrm/compat: Cleanup WARN()s that can be user-triggered

Replace WARN_ONCE() that can be triggered from userspace with
pr_warn_once(). Those still give user a hint what's the issue.

I've left WARN()s that are not possible to trigger with current
code-base and that would mean that the code has issues:
- relying on current compat_msg_min[type] <= xfrm_msg_min[type]
- expected 4-byte padding size difference between
  compat_msg_min[type] and xfrm_msg_min[type]
- compat_policy[type].len <= xfrma_policy[type].len
(for every type)

Reported-by: syzbot+834ffd1afc7212eb8147@syzkaller.appspotmail.com
Fixes: 5f3eea6b7e8f ("xfrm/compat: Attach xfrm dumps to 64=>32 bit translator")
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org
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 d8e8a11..a20aec9 100644 (file)
--- a/net/xfrm/xfrm_compat.c
+++ b/net/xfrm/xfrm_compat.c
@@ -216,7 +216,7 @@ static struct nlmsghdr *xfrm_nlmsg_put_compat(struct sk_buff *skb,
        case XFRM_MSG_GETSADINFO:
        case XFRM_MSG_GETSPDINFO:
        default:
-               WARN_ONCE(1, "unsupported nlmsg_type %d", nlh_src->nlmsg_type);
+               pr_warn_once("unsupported nlmsg_type %d\n", nlh_src->nlmsg_type);
                return ERR_PTR(-EOPNOTSUPP);
        }
 
@@ -277,7 +277,7 @@ static int xfrm_xlate64_attr(struct sk_buff *dst, const struct nlattr *src)
                return xfrm_nla_cpy(dst, src, nla_len(src));
        default:
                BUILD_BUG_ON(XFRMA_MAX != XFRMA_IF_ID);
-               WARN_ONCE(1, "unsupported nla_type %d", src->nla_type);
+               pr_warn_once("unsupported nla_type %d\n", src->nla_type);
                return -EOPNOTSUPP;
        }
 }
@@ -315,8 +315,10 @@ static int xfrm_alloc_compat(struct sk_buff *skb, const struct nlmsghdr *nlh_src
        struct sk_buff *new = NULL;
        int err;
 
-       if (WARN_ON_ONCE(type >= ARRAY_SIZE(xfrm_msg_min)))
+       if (type >= ARRAY_SIZE(xfrm_msg_min)) {
+               pr_warn_once("unsupported nlmsg_type %d\n", nlh_src->nlmsg_type);
                return -EOPNOTSUPP;
+       }
 
        if (skb_shinfo(skb)->frag_list == NULL) {
                new = alloc_skb(skb->len + skb_tailroom(skb), GFP_ATOMIC);
@@ -378,6 +380,10 @@ static int xfrm_attr_cpy32(void *dst, size_t *pos, const struct nlattr *src,
        struct nlmsghdr *nlmsg = dst;
        struct nlattr *nla;
 
+       /* xfrm_user_rcv_msg_compat() relies on fact that 32-bit messages
+        * have the same len or shorted than 64-bit ones.
+        * 32-bit translation that is bigger than 64-bit original is unexpected.
+        */
        if (WARN_ON_ONCE(copy_len > payload))
                copy_len = payload;