[NETFILTER]: nfnetlink_log: fix EPERM when binding/unbinding and instance 0 exists

When binding or unbinding to an address family, the res_id is usually set
to zero. When logging instance 0 already exists and is owned by a different
process, this makes nfunl_recv_config return -EPERM without performing
the bind operation.

Since no operation on the foreign logging instance itself was requested,
this is incorrect. Move bind/unbind commands before the queue instance
permissions checks.

Also remove an incorrect comment.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index c6802c0..bf3f19b 100644 (file)
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -702,20 +702,30 @@ nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
        struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
        u_int16_t group_num = ntohs(nfmsg->res_id);
        struct nfulnl_instance *inst;
+       struct nfulnl_msg_config_cmd *cmd = NULL;
        int ret = 0;
 
+       if (nfula[NFULA_CFG_CMD]) {
+               u_int8_t pf = nfmsg->nfgen_family;
+               cmd = nla_data(nfula[NFULA_CFG_CMD]);
+
+               /* Commands without queue context */
+               switch (cmd->command) {
+               case NFULNL_CFG_CMD_PF_BIND:
+                       return nf_log_register(pf, &nfulnl_logger);
+               case NFULNL_CFG_CMD_PF_UNBIND:
+                       nf_log_unregister_pf(pf);
+                       return 0;
+               }
+       }
+
        inst = instance_lookup_get(group_num);
        if (inst && inst->peer_pid != NETLINK_CB(skb).pid) {
                ret = -EPERM;
                goto out_put;
        }
 
-       if (nfula[NFULA_CFG_CMD]) {
-               u_int8_t pf = nfmsg->nfgen_family;
-               struct nfulnl_msg_config_cmd *cmd;
-
-               cmd = nla_data(nfula[NFULA_CFG_CMD]);
-
+       if (cmd != NULL) {
                switch (cmd->command) {
                case NFULNL_CFG_CMD_BIND:
                        if (inst) {
@@ -738,14 +748,6 @@ nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
 
                        instance_destroy(inst);
                        goto out;
-               case NFULNL_CFG_CMD_PF_BIND:
-                       ret = nf_log_register(pf, &nfulnl_logger);
-                       break;
-               case NFULNL_CFG_CMD_PF_UNBIND:
-                       /* This is a bug and a feature.  We cannot unregister
-                        * other handlers, like nfnetlink_inst can */
-                       nf_log_unregister_pf(pf);
-                       break;
                default:
                        ret = -ENOTSUPP;
                        break;