netfilter/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 <jdoll...@akamai.com>
Reviewed-by: Josh Hunt <joh...@akamai.com>
Signed-off-by: Vishwanath Pai <v...@akamai.com>
diff --git a/include/net/netfilter/nf_log.h b/include/net/netfilter/nf_log.h
index 57639fc..83d855b 100644
--- 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
--- 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
--- 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
--- 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;
