[PATCH 19/21] userns: xt_owner: Add basic user namespace support.

[Eric W. Biederman]

From: "Eric W. Biederman" <ebied...@xmission.com>

- Only allow adding matches from the initial user namespace
- Add the appropriate conversion functions to handle matches
  against sockets in other user namespaces.

Cc: Jan Engelhardt <jeng...@medozas.de>
Cc: Patrick McHardy <ka...@trash.net>
Cc: Pablo Neira Ayuso <pa...@netfilter.org>
Acked-by: Serge Hallyn <serge.hal...@canonical.com>
Signed-off-by: Eric W. Biederman <ebied...@xmission.com>
---
 init/Kconfig             |    1 -
 net/netfilter/xt_owner.c |   30 ++++++++++++++++++++++++------
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 40f5020..76ffca9 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -943,7 +943,6 @@ config UIDGID_CONVERTED
 
        # Networking
        depends on NET_9P = n
-       depends on NETFILTER_XT_MATCH_OWNER = n
        depends on AF_RXRPC = n
        depends on NET_KEY = n
        depends on DNS_RESOLVER = n
diff --git a/net/netfilter/xt_owner.c b/net/netfilter/xt_owner.c
index 772d738..ca2e577 100644
--- a/net/netfilter/xt_owner.c
+++ b/net/netfilter/xt_owner.c
@@ -17,6 +17,17 @@
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter/xt_owner.h>
 
+static int owner_check(const struct xt_mtchk_param *par)
+{
+       struct xt_owner_match_info *info = par->matchinfo;
+
+       /* For now only allow adding matches from the initial user namespace */
+       if ((info->match & (XT_OWNER_UID|XT_OWNER_GID)) &&
+           (current_user_ns() != &init_user_ns))
+               return -EINVAL;
+       return 0;
+}
+
 static bool
 owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
 {
@@ -37,17 +48,23 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param 
*par)
                return ((info->match ^ info->invert) &
                       (XT_OWNER_UID | XT_OWNER_GID)) == 0;
 
-       if (info->match & XT_OWNER_UID)
-               if ((filp->f_cred->fsuid >= info->uid_min &&
-                   filp->f_cred->fsuid <= info->uid_max) ^
+       if (info->match & XT_OWNER_UID) {
+               kuid_t uid_min = make_kuid(&init_user_ns, info->uid_min);
+               kuid_t uid_max = make_kuid(&init_user_ns, info->uid_max);
+               if ((uid_gte(filp->f_cred->fsuid, uid_min) &&
+                    uid_lte(filp->f_cred->fsuid, uid_max)) ^
                    !(info->invert & XT_OWNER_UID))
                        return false;
+       }
 
-       if (info->match & XT_OWNER_GID)
-               if ((filp->f_cred->fsgid >= info->gid_min &&
-                   filp->f_cred->fsgid <= info->gid_max) ^
+       if (info->match & XT_OWNER_GID) {
+               kgid_t gid_min = make_kgid(&init_user_ns, info->gid_min);
+               kgid_t gid_max = make_kgid(&init_user_ns, info->gid_max);
+               if ((gid_gte(filp->f_cred->fsgid, gid_min) &&
+                    gid_lte(filp->f_cred->fsgid, gid_max)) ^
                    !(info->invert & XT_OWNER_GID))
                        return false;
+       }
 
        return true;
 }
@@ -56,6 +73,7 @@ static struct xt_match owner_mt_reg __read_mostly = {
        .name       = "owner",
        .revision   = 1,
        .family     = NFPROTO_UNSPEC,
+       .checkentry = owner_check,
        .match      = owner_mt,
        .matchsize  = sizeof(struct xt_owner_match_info),
        .hooks      = (1 << NF_INET_LOCAL_OUT) |
-- 
1.7.5.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/