xfrm: Zero padding when dumping algos and encap

When copying data to user-space we should ensure that only valid
data is copied over.  Padding in structures may be filled with
random (possibly sensitve) data and should never be given directly
to user-space.

This patch fixes the copying of xfrm algorithms and the encap
template in xfrm_user so that padding is zeroed.

Reported-by: syzbot+fa5414772d5c445dac3c@syzkaller.appspotmail.com
Reported-by: Hyunwoo Kim <v4bel@theori.io>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index cf5172d..103af2b 100644 (file)
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1012,7 +1012,9 @@ static int copy_to_user_aead(struct xfrm_algo_aead *aead, struct sk_buff *skb)
                return -EMSGSIZE;
 
        ap = nla_data(nla);
-       memcpy(ap, aead, sizeof(*aead));
+       strscpy_pad(ap->alg_name, aead->alg_name, sizeof(ap->alg_name));
+       ap->alg_key_len = aead->alg_key_len;
+       ap->alg_icv_len = aead->alg_icv_len;
 
        if (redact_secret && aead->alg_key_len)
                memset(ap->alg_key, 0, (aead->alg_key_len + 7) / 8);
@@ -1032,7 +1034,8 @@ static int copy_to_user_ealg(struct xfrm_algo *ealg, struct sk_buff *skb)
                return -EMSGSIZE;
 
        ap = nla_data(nla);
-       memcpy(ap, ealg, sizeof(*ealg));
+       strscpy_pad(ap->alg_name, ealg->alg_name, sizeof(ap->alg_name));
+       ap->alg_key_len = ealg->alg_key_len;
 
        if (redact_secret && ealg->alg_key_len)
                memset(ap->alg_key, 0, (ealg->alg_key_len + 7) / 8);
@@ -1043,6 +1046,40 @@ static int copy_to_user_ealg(struct xfrm_algo *ealg, struct sk_buff *skb)
        return 0;
 }
 
+static int copy_to_user_calg(struct xfrm_algo *calg, struct sk_buff *skb)
+{
+       struct nlattr *nla = nla_reserve(skb, XFRMA_ALG_COMP, sizeof(*calg));
+       struct xfrm_algo *ap;
+
+       if (!nla)
+               return -EMSGSIZE;
+
+       ap = nla_data(nla);
+       strscpy_pad(ap->alg_name, calg->alg_name, sizeof(ap->alg_name));
+       ap->alg_key_len = 0;
+
+       return 0;
+}
+
+static int copy_to_user_encap(struct xfrm_encap_tmpl *ep, struct sk_buff *skb)
+{
+       struct nlattr *nla = nla_reserve(skb, XFRMA_ENCAP, sizeof(*ep));
+       struct xfrm_encap_tmpl *uep;
+
+       if (!nla)
+               return -EMSGSIZE;
+
+       uep = nla_data(nla);
+       memset(uep, 0, sizeof(*uep));
+
+       uep->encap_type = ep->encap_type;
+       uep->encap_sport = ep->encap_sport;
+       uep->encap_dport = ep->encap_dport;
+       uep->encap_oa = ep->encap_oa;
+
+       return 0;
+}
+
 static int xfrm_smark_put(struct sk_buff *skb, struct xfrm_mark *m)
 {
        int ret = 0;
@@ -1098,12 +1135,12 @@ static int copy_to_user_state_extra(struct xfrm_state *x,
                        goto out;
        }
        if (x->calg) {
-               ret = nla_put(skb, XFRMA_ALG_COMP, sizeof(*(x->calg)), x->calg);
+               ret = copy_to_user_calg(x->calg, skb);
                if (ret)
                        goto out;
        }
        if (x->encap) {
-               ret = nla_put(skb, XFRMA_ENCAP, sizeof(*x->encap), x->encap);
+               ret = copy_to_user_encap(x->encap, skb);
                if (ret)
                        goto out;
        }