xfrm: Validate address prefix lengths in the xfrm selector.

BugLink: https://bugs.launchpad.net/bugs/1836654
[ Upstream commit 07bf7908950a8b14e81aa1807e3c667eab39287a ]

We don't validate the address prefix lengths in the xfrm
selector we got from userspace. This can lead to undefined
behaviour in the address matching functions if the prefix
is too big for the given address family. Fix this by checking
the prefixes and refuse SA/policy insertation when a prefix
is invalid.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Air Icy <icytxw@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 33878e6e0d0a01cdc5da8ab20bdb92d0d93e056d..5151b3ebf0688bc4195f61c3b6bbda4bbbcded6a 100644 (file)
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -151,10 +151,16 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
        err = -EINVAL;
        switch (p->family) {
        case AF_INET:
+               if (p->sel.prefixlen_d > 32 || p->sel.prefixlen_s > 32)
+                       goto out;
+
                break;
 
        case AF_INET6:
 #if IS_ENABLED(CONFIG_IPV6)
+               if (p->sel.prefixlen_d > 128 || p->sel.prefixlen_s > 128)
+                       goto out;
+
                break;
 #else
                err = -EAFNOSUPPORT;
@@ -1359,10 +1365,16 @@ static int verify_newpolicy_info(struct xfrm_userpolicy_info *p)
 
        switch (p->sel.family) {
        case AF_INET:
+               if (p->sel.prefixlen_d > 32 || p->sel.prefixlen_s > 32)
+                       return -EINVAL;
+
                break;
 
        case AF_INET6:
 #if IS_ENABLED(CONFIG_IPV6)
+               if (p->sel.prefixlen_d > 128 || p->sel.prefixlen_s > 128)
+                       return -EINVAL;
+
                break;
 #else
                return  -EAFNOSUPPORT;