[PATCH 2/5] netlink: have netlink per-protocol bind function return an error code.

[Richard Guy Briggs]

Have the netlink per-protocol optional bind function return an error code
rather than void to signal a failure.

This will enable netlink protocols to perform extra checks including
capabilities and permissions verifications when updating memberships in
multicast groups.

Signed-off-by: Richard Guy Briggs <r...@redhat.com>
---
 include/linux/netlink.h   |    2 +-
 net/netfilter/nfnetlink.c |    6 ++++--
 net/netlink/af_netlink.c  |   30 +++++++++++++++++-------------
 net/netlink/af_netlink.h  |    4 ++--
 4 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 7a6c396..4402653 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -45,7 +45,7 @@ struct netlink_kernel_cfg {
        unsigned int    flags;
        void            (*input)(struct sk_buff *skb);
        struct mutex    *cb_mutex;
-       void            (*bind)(int group);
+       int             (*bind)(int group);
        bool            (*compare)(struct net *net, struct sock *sk);
 };
 
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 046aa13..0edc4d6 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -392,7 +392,7 @@ static void nfnetlink_rcv(struct sk_buff *skb)
 }
 
 #ifdef CONFIG_MODULES
-static void nfnetlink_bind(int group)
+static int nfnetlink_bind(int group)
 {
        const struct nfnetlink_subsystem *ss;
        int type = nfnl_group2type[group];
@@ -402,9 +402,11 @@ static void nfnetlink_bind(int group)
        if (!ss) {
                rcu_read_unlock();
                request_module("nfnetlink-subsys-%d", type);
-               return;
+               return 0;
        }
        rcu_read_unlock();
+
+       return 0;
 }
 #endif
 
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index bca50b9..755912f 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1198,7 +1198,7 @@ static int netlink_create(struct net *net, struct socket 
*sock, int protocol,
        struct module *module = NULL;
        struct mutex *cb_mutex;
        struct netlink_sock *nlk;
-       void (*bind)(int group);
+       int (*bind)(int group);
        int err = 0;
 
        sock->state = SS_UNCONNECTED;
@@ -1441,6 +1441,17 @@ static int netlink_bind(struct socket *sock, struct 
sockaddr *addr,
        if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
                return 0;
 
+       if (nlk->netlink_bind && nladdr->nl_groups) {
+               int i;
+
+               for (i=0; i<nlk->ngroups; i++)
+                       if (test_bit(i, (long unsigned int 
*)&nladdr->nl_groups)) {
+                               err = nlk->netlink_bind(i);
+                               if (err)
+                                       return err;
+                       }
+       }
+
        netlink_table_grab();
        netlink_update_subscriptions(sk, nlk->subscriptions +
                                         hweight32(nladdr->nl_groups) -
@@ -1449,15 +1460,6 @@ static int netlink_bind(struct socket *sock, struct 
sockaddr *addr,
        netlink_update_listeners(sk);
        netlink_table_ungrab();
 
-       if (nlk->netlink_bind && nlk->groups[0]) {
-               int i;
-
-               for (i=0; i<nlk->ngroups; i++) {
-                       if (test_bit(i, nlk->groups))
-                               nlk->netlink_bind(i);
-               }
-       }
-
        return 0;
 }
 
@@ -2095,14 +2097,16 @@ static int netlink_setsockopt(struct socket *sock, int 
level, int optname,
                        return err;
                if (!val || val - 1 >= nlk->ngroups)
                        return -EINVAL;
+               if (nlk->netlink_bind) {
+                       err = nlk->netlink_bind(val);
+                       if (err)
+                               return err;
+               }
                netlink_table_grab();
                netlink_update_socket_mc(nlk, val,
                                         optname == NETLINK_ADD_MEMBERSHIP);
                netlink_table_ungrab();
 
-               if (nlk->netlink_bind)
-                       nlk->netlink_bind(val);
-
                err = 0;
                break;
        }
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index acbd774..0edb8d5 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -37,7 +37,7 @@ struct netlink_sock {
        struct mutex            *cb_mutex;
        struct mutex            cb_def_mutex;
        void                    (*netlink_rcv)(struct sk_buff *skb);
-       void                    (*netlink_bind)(int group);
+       int                     (*netlink_bind)(int group);
        struct module           *module;
 #ifdef CONFIG_NETLINK_MMAP
        struct mutex            pg_vec_lock;
@@ -73,7 +73,7 @@ struct netlink_table {
        unsigned int            groups;
        struct mutex            *cb_mutex;
        struct module           *module;
-       void                    (*bind)(int group);
+       int                     (*bind)(int group);
        bool                    (*compare)(struct net *net, struct sock *sock);
        int                     registered;
 };
-- 
1.7.1

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