net: ppp: use sk_unattached_filter api

For the ppp driver, there are currently two open-coded BPF filters in use,
that is, pass_filter and active_filter. Migrate both to make proper use
of sk_unattached_filter_{create,destroy} API so that the actual BPF code
is decoupled from direct access, and filters can be jited as a side-effect
by the internal filter compiler.

Joint work with Alexei Starovoitov.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linux-ppp@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 41 insertions, 19 deletions

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 72ff14b811c6..e3923ebb693f 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -143,9 +143,8 @@ struct ppp {
         struct sk_buff_head mrq;        /* MP: receive reconstruction queue */
 #endif /* CONFIG_PPP_MULTILINK */
 #ifdef CONFIG_PPP_FILTER
-        struct sock_filter *pass_filter;        /* filter for packets to pass */
-        struct sock_filter *active_filter;/* filter for pkts to reset idle */
-        unsigned pass_len, active_len;
+        struct sk_filter *pass_filter;  /* filter for packets to pass */
+        struct sk_filter *active_filter;/* filter for pkts to reset idle */
 #endif /* CONFIG_PPP_FILTER */
         struct net      *ppp_net;       /* the net we belong to */
         struct ppp_link_stats stats64;  /* 64 bit network stats */
@@ -755,28 +754,42 @@ static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         case PPPIOCSPASS:
         {
                 struct sock_filter *code;
+
                 err = get_filter(argp, &code);
                 if (err >= 0) {
+                        struct sock_fprog fprog = {
+                                .len = err,
+                                .filter = code,
+                        };
+
                         ppp_lock(ppp);
-                        kfree(ppp->pass_filter);
-                        ppp->pass_filter = code;
-                        ppp->pass_len = err;
+                        if (ppp->pass_filter)
+                                sk_unattached_filter_destroy(ppp->pass_filter);
+                        err = sk_unattached_filter_create(&ppp->pass_filter,
+                                                          &fprog);
+                        kfree(code);
                         ppp_unlock(ppp);
-                        err = 0;
                 }
                 break;
         }
         case PPPIOCSACTIVE:
         {
                 struct sock_filter *code;
+
                 err = get_filter(argp, &code);
                 if (err >= 0) {
+                        struct sock_fprog fprog = {
+                                .len = err,
+                                .filter = code,
+                        };
+
                         ppp_lock(ppp);
-                        kfree(ppp->active_filter);
-                        ppp->active_filter = code;
-                        ppp->active_len = err;
+                        if (ppp->active_filter)
+                                sk_unattached_filter_destroy(ppp->active_filter);
+                        err = sk_unattached_filter_create(&ppp->active_filter,
+                                                          &fprog);
+                        kfree(code);
                         ppp_unlock(ppp);
-                        err = 0;
                 }
                 break;
         }
@@ -1184,7 +1197,7 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
                    a four-byte PPP header on each packet */
                 *skb_push(skb, 2) = 1;
                 if (ppp->pass_filter &&
-                    sk_run_filter(skb, ppp->pass_filter) == 0) {
+                    SK_RUN_FILTER(ppp->pass_filter, skb) == 0) {
                         if (ppp->debug & 1)
                                 netdev_printk(KERN_DEBUG, ppp->dev,
                                               "PPP: outbound frame "
@@ -1194,7 +1207,7 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
                 }
                 /* if this packet passes the active filter, record the time */
                 if (!(ppp->active_filter &&
-                      sk_run_filter(skb, ppp->active_filter) == 0))
+                      SK_RUN_FILTER(ppp->active_filter, skb) == 0))
                         ppp->last_xmit = jiffies;
                 skb_pull(skb, 2);
 #else
@@ -1818,7 +1831,7 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
 
                         *skb_push(skb, 2) = 0;
                         if (ppp->pass_filter &&
-                            sk_run_filter(skb, ppp->pass_filter) == 0) {
+                            SK_RUN_FILTER(ppp->pass_filter, skb) == 0) {
                                 if (ppp->debug & 1)
                                         netdev_printk(KERN_DEBUG, ppp->dev,
                                                       "PPP: inbound frame "
@@ -1827,7 +1840,7 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
                                 return;
                         }
                         if (!(ppp->active_filter &&
-                              sk_run_filter(skb, ppp->active_filter) == 0))
+                              SK_RUN_FILTER(ppp->active_filter, skb) == 0))
                                 ppp->last_recv = jiffies;
                         __skb_pull(skb, 2);
                 } else
@@ -2672,6 +2685,10 @@ ppp_create_interface(struct net *net, int unit, int *retp)
         ppp->minseq = -1;
         skb_queue_head_init(&ppp->mrq);
 #endif /* CONFIG_PPP_MULTILINK */
+#ifdef CONFIG_PPP_FILTER
+        ppp->pass_filter = NULL;
+        ppp->active_filter = NULL;
+#endif /* CONFIG_PPP_FILTER */
 
         /*
          * drum roll: don't forget to set
@@ -2802,10 +2819,15 @@ static void ppp_destroy_interface(struct ppp *ppp)
         skb_queue_purge(&ppp->mrq);
 #endif /* CONFIG_PPP_MULTILINK */
 #ifdef CONFIG_PPP_FILTER
-        kfree(ppp->pass_filter);
-        ppp->pass_filter = NULL;
-        kfree(ppp->active_filter);
-        ppp->active_filter = NULL;
+        if (ppp->pass_filter) {
+                sk_unattached_filter_destroy(ppp->pass_filter);
+                ppp->pass_filter = NULL;
+        }
+
+        if (ppp->active_filter) {
+                sk_unattached_filter_destroy(ppp->active_filter);
+                ppp->active_filter = NULL;
+        }
 #endif /* CONFIG_PPP_FILTER */
 
         kfree_skb(ppp->xmit_pending);