[1/2] xfrm: Zero padding when dumping algos and encap

Commit Message

Steffen Klassert March 15, 2023, 10:56 a.m. UTC

From: Herbert Xu <[e-mail]>

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: [e-mail]
Reported-by: Hyunwoo Kim <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>
Reviewed-by: Sabrina Dubroca <[e-mail]>
Signed-off-by: Steffen Klassert <[e-mail]>
---
 net/xfrm/xfrm_user.c | 45 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 4 deletions(-)

Comments

[e-mail] March 17, 2023, 12:30 a.m. UTC | #1

Hello:

This series was applied to netdev/net.git (main)
by Steffen Klassert <[e-mail]>:

On Wed, 15 Mar 2023 11:56:22 +0100 you wrote:
> From: Herbert Xu <[e-mail]>
> 
> 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.
> 
> [...]

Here is the summary with links:
  - [1/2] xfrm: Zero padding when dumping algos and encap
    https://git.kernel.org/netdev/net/c/8222d5910dae
  - [2/2] xfrm: Allow transport-mode states with AF_UNSPEC selector
    https://git.kernel.org/netdev/net/c/c276a706ea1f

You are awesome, thank you!

Patch

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index cf5172d4ce68..103af2b3e986 100644
--- 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;
 	}