* [PATCH v7 nf] netfilter: synproxy: Check oom when adding synproxy and seqadj ct extensions
@ 2016-09-09 14:50 fgao
2016-09-12 17:15 ` Pablo Neira Ayuso
0 siblings, 1 reply; 2+ messages in thread
From: fgao @ 2016-09-09 14:50 UTC (permalink / raw)
To: pablo, netfilter-devel; +Cc: gfree.wind, Gao Feng
From: Gao Feng <fgao@ikuai8.com>
When memory is exhausted, nfct_seqadj_ext_add may fail to add the
synproxy and seqadj extensions. The function nf_ct_seqadj_init doesn't
check if get valid seqadj pointer by the nfct_seqadj.
Now drop the packet directly when fail to add seqadj extension to
avoid dereference NULL pointer in nf_ct_seqadj_init from
init_conntrack().
Signed-off-by: Gao Feng <fgao@ikuai8.com>
---
v7: Remove one debug log and revert to NF_DROP again;
v6: Add one helper function to add synproxy
v5: Return NF_ACCEPT instead of NF_DROP when nfct_seqadj_ext_add failed in nf_nat_setup_info
v4: Drop the packet directly when fail to add seqadj extension;
v3: Remove the warning log when seqadj is null;
v2: Remove the unnessary seqadj check in nf_ct_seq_adjust
v1: Initial patch
include/net/netfilter/nf_conntrack_synproxy.h | 13 +++++++++++++
net/netfilter/nf_conntrack_core.c | 6 +++---
net/netfilter/nf_nat_core.c | 3 ++-
3 files changed, 18 insertions(+), 4 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack_synproxy.h b/include/net/netfilter/nf_conntrack_synproxy.h
index 6793614..e8cf825 100644
--- a/include/net/netfilter/nf_conntrack_synproxy.h
+++ b/include/net/netfilter/nf_conntrack_synproxy.h
@@ -27,6 +27,19 @@ static inline struct nf_conn_synproxy *nfct_synproxy_ext_add(struct nf_conn *ct)
#endif
}
+static inline bool nf_ct_add_synproxy(struct nf_conn *ct, const struct nf_conn *tmpl)
+{
+ if (tmpl && nfct_synproxy(tmpl)) {
+ if (!nfct_seqadj_ext_add(ct))
+ return false;
+
+ if (!nfct_synproxy_ext_add(ct))
+ return false;
+ }
+
+ return true;
+}
+
struct synproxy_stats {
unsigned int syn_received;
unsigned int cookie_invalid;
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index dd2c43a..64aabeb 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1035,9 +1035,9 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
if (IS_ERR(ct))
return (struct nf_conntrack_tuple_hash *)ct;
- if (tmpl && nfct_synproxy(tmpl)) {
- nfct_seqadj_ext_add(ct);
- nfct_synproxy_ext_add(ct);
+ if (!nf_ct_add_synproxy(ct, tmpl)) {
+ nf_conntrack_free(ct);
+ return NULL;
}
timeout_ext = tmpl ? nf_ct_timeout_find(tmpl) : NULL;
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index de31818..b82282a 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -441,7 +441,8 @@ nf_nat_setup_info(struct nf_conn *ct,
ct->status |= IPS_DST_NAT;
if (nfct_help(ct))
- nfct_seqadj_ext_add(ct);
+ if (!nfct_seqadj_ext_add(ct))
+ return NF_DROP;
}
if (maniptype == NF_NAT_MANIP_SRC) {
--
1.9.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v7 nf] netfilter: synproxy: Check oom when adding synproxy and seqadj ct extensions
2016-09-09 14:50 [PATCH v7 nf] netfilter: synproxy: Check oom when adding synproxy and seqadj ct extensions fgao
@ 2016-09-12 17:15 ` Pablo Neira Ayuso
0 siblings, 0 replies; 2+ messages in thread
From: Pablo Neira Ayuso @ 2016-09-12 17:15 UTC (permalink / raw)
To: fgao; +Cc: netfilter-devel, gfree.wind
On Fri, Sep 09, 2016 at 10:50:21PM +0800, fgao@ikuai8.com wrote:
> From: Gao Feng <fgao@ikuai8.com>
>
> When memory is exhausted, nfct_seqadj_ext_add may fail to add the
> synproxy and seqadj extensions. The function nf_ct_seqadj_init doesn't
> check if get valid seqadj pointer by the nfct_seqadj.
>
> Now drop the packet directly when fail to add seqadj extension to
> avoid dereference NULL pointer in nf_ct_seqadj_init from
> init_conntrack().
>
> Signed-off-by: Gao Feng <fgao@ikuai8.com>
> ---
> v7: Remove one debug log and revert to NF_DROP again;
> v6: Add one helper function to add synproxy
> v5: Return NF_ACCEPT instead of NF_DROP when nfct_seqadj_ext_add failed in nf_nat_setup_info
> v4: Drop the packet directly when fail to add seqadj extension;
> v3: Remove the warning log when seqadj is null;
> v2: Remove the unnessary seqadj check in nf_ct_seq_adjust
> v1: Initial patch
>
> include/net/netfilter/nf_conntrack_synproxy.h | 13 +++++++++++++
> net/netfilter/nf_conntrack_core.c | 6 +++---
> net/netfilter/nf_nat_core.c | 3 ++-
> 3 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/include/net/netfilter/nf_conntrack_synproxy.h b/include/net/netfilter/nf_conntrack_synproxy.h
> index 6793614..e8cf825 100644
> --- a/include/net/netfilter/nf_conntrack_synproxy.h
> +++ b/include/net/netfilter/nf_conntrack_synproxy.h
> @@ -27,6 +27,19 @@ static inline struct nf_conn_synproxy *nfct_synproxy_ext_add(struct nf_conn *ct)
> #endif
> }
>
> +static inline bool nf_ct_add_synproxy(struct nf_conn *ct, const struct nf_conn *tmpl)
> +{
> + if (tmpl && nfct_synproxy(tmpl)) {
> + if (!nfct_seqadj_ext_add(ct))
> + return false;
> +
> + if (!nfct_synproxy_ext_add(ct))
> + return false;
> + }
> +
> + return true;
> +}
> +
> struct synproxy_stats {
> unsigned int syn_received;
> unsigned int cookie_invalid;
> diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
> index dd2c43a..64aabeb 100644
> --- a/net/netfilter/nf_conntrack_core.c
> +++ b/net/netfilter/nf_conntrack_core.c
> @@ -1035,9 +1035,9 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
> if (IS_ERR(ct))
> return (struct nf_conntrack_tuple_hash *)ct;
>
> - if (tmpl && nfct_synproxy(tmpl)) {
> - nfct_seqadj_ext_add(ct);
> - nfct_synproxy_ext_add(ct);
> + if (!nf_ct_add_synproxy(ct, tmpl)) {
> + nf_conntrack_free(ct);
> + return NULL;
This has to be ERR_PTR(-ENOMEM);
So the packet is dropped.
NULL is used for invalid packets, invalid packets keep going and the
user can drop them via -m state --state INVALID.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2016-09-09 14:50 [PATCH v7 nf] netfilter: synproxy: Check oom when adding synproxy and seqadj ct extensions fgao
2016-09-12 17:15 ` Pablo Neira Ayuso
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