netfilter: log: netns NULL ptr bug when calling from conntrack

Since (69b34fb netfilter: xt_LOG: add net namespace support
for xt_LOG), we hit this:

[ 4224.708977] BUG: unable to handle kernel NULL pointer dereference at 0000000000000388
[ 4224.709074] IP: [<ffffffff8147f699>] ipt_log_packet+0x29/0x270

when callling log functions from conntrack both in and out
are NULL i.e. the net pointer is invalid.

Adding struct net *net in call to nf_logfn() will secure that
there always is a vaild net ptr.

Reported as netfilter's bugzilla bug 818:
https://bugzilla.netfilter.org/show_bug.cgi?id=818

Reported-by: Ronald <ronald645@gmail.com>
Signed-off-by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

4 files changed, 12 insertions, 10 deletions

diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 757951d251e3..3b18dd1be7d9 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -148,7 +148,7 @@ void nf_log_packet(struct net *net,
                 va_start(args, fmt);
                 vsnprintf(prefix, sizeof(prefix), fmt, args);
                 va_end(args);
-                logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
+                logger->logfn(net, pf, hooknum, skb, in, out, loginfo, prefix);
         }
         rcu_read_unlock();
 }
diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index d83d881002a6..962e9792e317 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -602,7 +602,8 @@ static struct nf_loginfo default_loginfo = {
 
 /* log handler for internal netfilter logging api */
 void
-nfulnl_log_packet(u_int8_t pf,
+nfulnl_log_packet(struct net *net,
+                  u_int8_t pf,
                   unsigned int hooknum,
                   const struct sk_buff *skb,
                   const struct net_device *in,
@@ -615,7 +616,6 @@ nfulnl_log_packet(u_int8_t pf,
         const struct nf_loginfo *li;
         unsigned int qthreshold;
         unsigned int plen;
-        struct net *net = dev_net(in ? in : out);
         struct nfnl_log_net *log = nfnl_log_pernet(net);
 
         if (li_user && li_user->type == NF_LOG_TYPE_ULOG)
diff --git a/net/netfilter/xt_LOG.c b/net/netfilter/xt_LOG.c
index fe573f6c9e91..491c7d821a0b 100644
--- a/net/netfilter/xt_LOG.c
+++ b/net/netfilter/xt_LOG.c
@@ -466,7 +466,8 @@ log_packet_common(struct sbuff *m,
 
 
 static void
-ipt_log_packet(u_int8_t pf,
+ipt_log_packet(struct net *net,
+               u_int8_t pf,
                unsigned int hooknum,
                const struct sk_buff *skb,
                const struct net_device *in,
@@ -475,7 +476,6 @@ ipt_log_packet(u_int8_t pf,
                const char *prefix)
 {
         struct sbuff *m;
-        struct net *net = dev_net(in ? in : out);
 
         /* FIXME: Disabled from containers until syslog ns is supported */
         if (!net_eq(net, &init_net))
@@ -797,7 +797,8 @@ fallback:
 }
 
 static void
-ip6t_log_packet(u_int8_t pf,
+ip6t_log_packet(struct net *net,
+                u_int8_t pf,
                 unsigned int hooknum,
                 const struct sk_buff *skb,
                 const struct net_device *in,
@@ -806,7 +807,6 @@ ip6t_log_packet(u_int8_t pf,
                 const char *prefix)
 {
         struct sbuff *m;
-        struct net *net = dev_net(in ? in : out);
 
         /* FIXME: Disabled from containers until syslog ns is supported */
         if (!net_eq(net, &init_net))
@@ -833,17 +833,18 @@ log_tg(struct sk_buff *skb, const struct xt_action_param *par)
 {
         const struct xt_log_info *loginfo = par->targinfo;
         struct nf_loginfo li;
+        struct net *net = dev_net(par->in ? par->in : par->out);
 
         li.type = NF_LOG_TYPE_LOG;
         li.u.log.level = loginfo->level;
         li.u.log.logflags = loginfo->logflags;
 
         if (par->family == NFPROTO_IPV4)
-                ipt_log_packet(NFPROTO_IPV4, par->hooknum, skb, par->in,
+                ipt_log_packet(net, NFPROTO_IPV4, par->hooknum, skb, par->in,
                                par->out, &li, loginfo->prefix);
 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
         else if (par->family == NFPROTO_IPV6)
-                ip6t_log_packet(NFPROTO_IPV6, par->hooknum, skb, par->in,
+                ip6t_log_packet(net, NFPROTO_IPV6, par->hooknum, skb, par->in,
                                 par->out, &li, loginfo->prefix);
 #endif
         else
diff --git a/net/netfilter/xt_NFLOG.c b/net/netfilter/xt_NFLOG.c
index a17dd0f589b2..fb7497c928a0 100644
--- a/net/netfilter/xt_NFLOG.c
+++ b/net/netfilter/xt_NFLOG.c
@@ -26,13 +26,14 @@ nflog_tg(struct sk_buff *skb, const struct xt_action_param *par)
 {
         const struct xt_nflog_info *info = par->targinfo;
         struct nf_loginfo li;
+        struct net *net = dev_net(par->in ? par->in : par->out);
 
         li.type              = NF_LOG_TYPE_ULOG;
         li.u.ulog.copy_len   = info->len;
         li.u.ulog.group      = info->group;
         li.u.ulog.qthreshold = info->threshold;
 
-        nfulnl_log_packet(par->family, par->hooknum, skb, par->in,
+        nfulnl_log_packet(net, par->family, par->hooknum, skb, par->in,
                           par->out, &li, info->prefix);
         return XT_CONTINUE;
 }