From: Liping Zhang <zlpnobody@xxxxxxxxx>
First, log prefix will be truncated to NF_LOG_PREFIXLEN-1, i.e. 127,
at nf_log_packet(), so the extra part is useless.
Second, after adding a log rule with a very very long prefix, we will
fail to dump the nft rules after this _special_ one, but acctually,
they do exist. For example:
# name_65000=$(printf "%0.sQ" {1..65000})
# nft add rule filter output log prefix "$name_65000"
# nft add rule filter output counter
# nft add rule filter output counter
# nft list chain filter output
table ip filter {
chain output {
type filter hook output priority 0; policy accept;
}
}
So now, restrict the log prefix length to NF_LOG_PREFIXLEN-1.
Fixes: 96518518cc41 ("netfilter: add nftables")
Signed-off-by: Liping Zhang <zlpnobody@xxxxxxxxx>
---
I think this is different with http://patchwork.ozlabs.org/patch/717635/.
So another separate patch will be better.
include/uapi/linux/netfilter/nf_log.h | 2 ++
net/netfilter/nf_log.c | 1 -
net/netfilter/nft_log.c | 3 ++-
3 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/netfilter/nf_log.h b/include/uapi/linux/netfilter/nf_log.h
index 8be21e0..d0b5fa9 100644
--- a/include/uapi/linux/netfilter/nf_log.h
+++ b/include/uapi/linux/netfilter/nf_log.h
@@ -9,4 +9,6 @@
#define NF_LOG_MACDECODE 0x20 /* Decode MAC header */
#define NF_LOG_MASK 0x2f
+#define NF_LOG_PREFIXLEN 128
+
#endif /* _NETFILTER_NF_LOG_H */
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 3dca90d..ffb9e8a 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -13,7 +13,6 @@
/* Internal logging interface, which relies on the real
LOG target modules */
-#define NF_LOG_PREFIXLEN 128
#define NFLOGGER_NAME_LEN 64
static struct nf_logger __rcu *loggers[NFPROTO_NUMPROTO][NF_LOG_TYPE_MAX] __read_mostly;
diff --git a/net/netfilter/nft_log.c b/net/netfilter/nft_log.c
index 6271e40..6f6e644 100644
--- a/net/netfilter/nft_log.c
+++ b/net/netfilter/nft_log.c
@@ -39,7 +39,8 @@ static void nft_log_eval(const struct nft_expr *expr,
static const struct nla_policy nft_log_policy[NFTA_LOG_MAX + 1] = {
[NFTA_LOG_GROUP] = { .type = NLA_U16 },
- [NFTA_LOG_PREFIX] = { .type = NLA_STRING },
+ [NFTA_LOG_PREFIX] = { .type = NLA_STRING,
+ .len = NF_LOG_PREFIXLEN - 1 },
[NFTA_LOG_SNAPLEN] = { .type = NLA_U32 },
[NFTA_LOG_QTHRESHOLD] = { .type = NLA_U16 },
[NFTA_LOG_LEVEL] = { .type = NLA_U32 },
--
2.5.5
--
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