netfilter: xt_NFLOG: nflog-range does not truncate packets

li->u.ulog.copy_len is currently ignored by the kernel, we should truncate
the packet to either li->u.ulog.copy_len (if set) or copy_range before
sending it to userspace. 0 is a valid input for copy_len, so add a new
flag to indicate whether this was option was specified by the user or not.

Add two flags to indicate whether nflog-size/copy_len was set or not.
XT_NFLOG_F_COPY_LEN is for XT_NFLOG and NFLOG_F_COPY_LEN for nfnetlink_log

On the userspace side, this was initially represented by the option
nflog-range, this will be replaced by --nflog-size now. --nflog-range would
still exist but does not do anything.

Reported-by: Joe Dollard <jdollard@akamai.com>
Reviewed-by: Josh Hunt <johunt@akamai.com>
Signed-off-by: Vishwanath Pai <vpai@akamai.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_log.h b/include/net/netfilter/nf_log.h
index 57639fc..83d855b 100644 (file)
--- a/include/net/netfilter/nf_log.h
+++ b/include/net/netfilter/nf_log.h
@@ -12,6 +12,9 @@
 #define NF_LOG_UID             0x08    /* Log UID owning local socket */
 #define NF_LOG_MASK            0x0f
 
+/* This flag indicates that copy_len field in nf_loginfo is set */
+#define NF_LOG_F_COPY_LEN      0x1
+
 enum nf_log_type {
        NF_LOG_TYPE_LOG         = 0,
        NF_LOG_TYPE_ULOG,
@@ -22,9 +25,13 @@ struct nf_loginfo {
        u_int8_t type;
        union {
                struct {
+                       /* copy_len will be used iff you set
+                        * NF_LOG_F_COPY_LEN in flags
+                        */
                        u_int32_t copy_len;
                        u_int16_t group;
                        u_int16_t qthreshold;
+                       u_int16_t flags;
                } ulog;
                struct {
                        u_int8_t level;

diff --git a/include/uapi/linux/netfilter/xt_NFLOG.h b/include/uapi/linux/netfilter/xt_NFLOG.h
index 87b5831..f330707 100644 (file)
--- a/include/uapi/linux/netfilter/xt_NFLOG.h
+++ b/include/uapi/linux/netfilter/xt_NFLOG.h
@@ -6,9 +6,13 @@
 #define XT_NFLOG_DEFAULT_GROUP         0x1
 #define XT_NFLOG_DEFAULT_THRESHOLD     0
 
-#define XT_NFLOG_MASK                  0x0
+#define XT_NFLOG_MASK                  0x1
+
+/* This flag indicates that 'len' field in xt_nflog_info is set*/
+#define XT_NFLOG_F_COPY_LEN            0x1
 
 struct xt_nflog_info {
+       /* 'len' will be used iff you set XT_NFLOG_F_COPY_LEN in flags */
        __u32   len;
        __u16   group;
        __u16   threshold;

diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index 11f81c8..cbcfdfb 100644 (file)
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -700,10 +700,13 @@ nfulnl_log_packet(struct net *net,
                break;
 
        case NFULNL_COPY_PACKET:
-               if (inst->copy_range > skb->len)
+               data_len = inst->copy_range;
+               if ((li->u.ulog.flags & NF_LOG_F_COPY_LEN) &&
+                   (li->u.ulog.copy_len < data_len))
+                       data_len = li->u.ulog.copy_len;
+
+               if (data_len > skb->len)
                        data_len = skb->len;
-               else
-                       data_len = inst->copy_range;
 
                size += nla_total_size(data_len);
                break;

diff --git a/net/netfilter/xt_NFLOG.c b/net/netfilter/xt_NFLOG.c
index a1fa2c8..018eed7 100644 (file)
--- a/net/netfilter/xt_NFLOG.c
+++ b/net/netfilter/xt_NFLOG.c
@@ -33,6 +33,9 @@ nflog_tg(struct sk_buff *skb, const struct xt_action_param *par)
        li.u.ulog.group      = info->group;
        li.u.ulog.qthreshold = info->threshold;
 
+       if (info->flags & XT_NFLOG_F_COPY_LEN)
+               li.u.ulog.flags |= NF_LOG_F_COPY_LEN;
+
        nfulnl_log_packet(net, par->family, par->hooknum, skb, par->in,
                          par->out, &li, info->prefix);
        return XT_CONTINUE;