net: Move the permission check in sock_diag_put_filterinfo to packet_diag_dump

The permission check in sock_diag_put_filterinfo is wrong, and it is so removed
from it's sources it is not clear why it is wrong.  Move the computation
into packet_diag_dump and pass a bool of the result into sock_diag_filterinfo.

This does not yet correct the capability check but instead simply moves it to make
it clear what is going on.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 9 insertions, 4 deletions

diff --git a/include/linux/sock_diag.h b/include/linux/sock_diag.h
index 302ab805b0bb..46cca4c06848 100644
--- a/include/linux/sock_diag.h
+++ b/include/linux/sock_diag.h
@@ -23,7 +23,7 @@ int sock_diag_check_cookie(void *sk, __u32 *cookie);
 void sock_diag_save_cookie(void *sk, __u32 *cookie);
 
 int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attr);
-int sock_diag_put_filterinfo(struct sock *sk,
+int sock_diag_put_filterinfo(bool may_report_filterinfo, struct sock *sk,
                              struct sk_buff *skb, int attrtype);
 
 #endif
diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c
index 9deb6abd6cf6..a4216a4c9572 100644
--- a/net/core/sock_diag.c
+++ b/net/core/sock_diag.c
@@ -49,7 +49,7 @@ int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attrtype)
 }
 EXPORT_SYMBOL_GPL(sock_diag_put_meminfo);
 
-int sock_diag_put_filterinfo(struct sock *sk,
+int sock_diag_put_filterinfo(bool may_report_filterinfo, struct sock *sk,
                              struct sk_buff *skb, int attrtype)
 {
         struct sock_fprog_kern *fprog;
@@ -58,7 +58,7 @@ int sock_diag_put_filterinfo(struct sock *sk,
         unsigned int flen;
         int err = 0;
 
-        if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {
+        if (!may_report_filterinfo) {
                 nla_reserve(skb, attrtype, 0);
                 return 0;
         }
diff --git a/net/packet/diag.c b/net/packet/diag.c
index 435ff99ba8c7..b34d0de24091 100644
--- a/net/packet/diag.c
+++ b/net/packet/diag.c
@@ -128,6 +128,7 @@ static int pdiag_put_fanout(struct packet_sock *po, struct sk_buff *nlskb)
 
 static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
                         struct packet_diag_req *req,
+                        bool may_report_filterinfo,
                         struct user_namespace *user_ns,
                         u32 portid, u32 seq, u32 flags, int sk_ino)
 {
@@ -172,7 +173,8 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
                 goto out_nlmsg_trim;
 
         if ((req->pdiag_show & PACKET_SHOW_FILTER) &&
-            sock_diag_put_filterinfo(sk, skb, PACKET_DIAG_FILTER))
+            sock_diag_put_filterinfo(may_report_filterinfo, sk, skb,
+                                     PACKET_DIAG_FILTER))
                 goto out_nlmsg_trim;
 
         return nlmsg_end(skb, nlh);
@@ -188,9 +190,11 @@ static int packet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
         struct packet_diag_req *req;
         struct net *net;
         struct sock *sk;
+        bool may_report_filterinfo;
 
         net = sock_net(skb->sk);
         req = nlmsg_data(cb->nlh);
+        may_report_filterinfo = ns_capable(net->user_ns, CAP_NET_ADMIN);
 
         mutex_lock(&net->packet.sklist_lock);
         sk_for_each(sk, &net->packet.sklist) {
@@ -200,6 +204,7 @@ static int packet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
                         goto next;
 
                 if (sk_diag_fill(sk, skb, req,
+                                 may_report_filterinfo,
                                  sk_user_ns(NETLINK_CB(cb->skb).sk),
                                  NETLINK_CB(cb->skb).portid,
                                  cb->nlh->nlmsg_seq, NLM_F_MULTI,