From f6cd14537ff9919081be19b9c53b9b19c0d3ea97 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Fri, 20 Apr 2018 15:15:03 -0400 Subject: [PATCH 1/3] net: sched: ife: signal not finding metaid We need to record stats for received metadata that we dont know how to process. Have find_decode_metaid() return -ENOENT to capture this. Signed-off-by: Alexander Aring Reviewed-by: Yotam Gigi Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- net/sched/act_ife.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c index a5994cf0512b..49b8ab551fbe 100644 --- a/net/sched/act_ife.c +++ b/net/sched/act_ife.c @@ -652,7 +652,7 @@ static int find_decode_metaid(struct sk_buff *skb, struct tcf_ife_info *ife, } } - return 0; + return -ENOENT; } static int tcf_ife_decode(struct sk_buff *skb, const struct tc_action *a, From cc74eddd0ff325d57373cea99f642b787d7f76f5 Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Fri, 20 Apr 2018 15:15:04 -0400 Subject: [PATCH 2/3] net: sched: ife: handle malformed tlv length There is currently no handling to check on a invalid tlv length. This patch adds such handling to avoid killing the kernel with a malformed ife packet. Signed-off-by: Alexander Aring Reviewed-by: Yotam Gigi Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- include/net/ife.h | 3 ++- net/ife/ife.c | 35 +++++++++++++++++++++++++++++++++-- net/sched/act_ife.c | 7 ++++++- 3 files changed, 41 insertions(+), 4 deletions(-) diff --git a/include/net/ife.h b/include/net/ife.h index 44b9c00f7223..e117617e3c34 100644 --- a/include/net/ife.h +++ b/include/net/ife.h @@ -12,7 +12,8 @@ void *ife_encode(struct sk_buff *skb, u16 metalen); void *ife_decode(struct sk_buff *skb, u16 *metalen); -void *ife_tlv_meta_decode(void *skbdata, u16 *attrtype, u16 *dlen, u16 *totlen); +void *ife_tlv_meta_decode(void *skbdata, const void *ifehdr_end, u16 *attrtype, + u16 *dlen, u16 *totlen); int ife_tlv_meta_encode(void *skbdata, u16 attrtype, u16 dlen, const void *dval); diff --git a/net/ife/ife.c b/net/ife/ife.c index 7d1ec76e7f43..7fbe70a0af4b 100644 --- a/net/ife/ife.c +++ b/net/ife/ife.c @@ -92,12 +92,43 @@ struct meta_tlvhdr { __be16 len; }; +static bool __ife_tlv_meta_valid(const unsigned char *skbdata, + const unsigned char *ifehdr_end) +{ + const struct meta_tlvhdr *tlv; + u16 tlvlen; + + if (unlikely(skbdata + sizeof(*tlv) > ifehdr_end)) + return false; + + tlv = (const struct meta_tlvhdr *)skbdata; + tlvlen = ntohs(tlv->len); + + /* tlv length field is inc header, check on minimum */ + if (tlvlen < NLA_HDRLEN) + return false; + + /* overflow by NLA_ALIGN check */ + if (NLA_ALIGN(tlvlen) < tlvlen) + return false; + + if (unlikely(skbdata + NLA_ALIGN(tlvlen) > ifehdr_end)) + return false; + + return true; +} + /* Caller takes care of presenting data in network order */ -void *ife_tlv_meta_decode(void *skbdata, u16 *attrtype, u16 *dlen, u16 *totlen) +void *ife_tlv_meta_decode(void *skbdata, const void *ifehdr_end, u16 *attrtype, + u16 *dlen, u16 *totlen) { - struct meta_tlvhdr *tlv = (struct meta_tlvhdr *) skbdata; + struct meta_tlvhdr *tlv; + if (!__ife_tlv_meta_valid(skbdata, ifehdr_end)) + return NULL; + + tlv = (struct meta_tlvhdr *)skbdata; *dlen = ntohs(tlv->len) - NLA_HDRLEN; *attrtype = ntohs(tlv->type); diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c index 49b8ab551fbe..8527cfdc446d 100644 --- a/net/sched/act_ife.c +++ b/net/sched/act_ife.c @@ -682,7 +682,12 @@ static int tcf_ife_decode(struct sk_buff *skb, const struct tc_action *a, u16 mtype; u16 dlen; - curr_data = ife_tlv_meta_decode(tlv_data, &mtype, &dlen, NULL); + curr_data = ife_tlv_meta_decode(tlv_data, ifehdr_end, &mtype, + &dlen, NULL); + if (!curr_data) { + qstats_drop_inc(this_cpu_ptr(ife->common.cpu_qstats)); + return TC_ACT_SHOT; + } if (find_decode_metaid(skb, ife, mtype, dlen, curr_data)) { /* abuse overlimits to count when we receive metadata From d57493d6d1be26c8ac8516a4463bfe24956978eb Mon Sep 17 00:00:00 2001 From: Alexander Aring Date: Fri, 20 Apr 2018 15:15:05 -0400 Subject: [PATCH 3/3] net: sched: ife: check on metadata length This patch checks if sk buffer is available to dererence ife header. If not then NULL will returned to signal an malformed ife packet. This avoids to crashing the kernel from outside. Signed-off-by: Alexander Aring Reviewed-by: Yotam Gigi Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- net/ife/ife.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ife/ife.c b/net/ife/ife.c index 7fbe70a0af4b..13bbf8cb6a39 100644 --- a/net/ife/ife.c +++ b/net/ife/ife.c @@ -69,6 +69,9 @@ void *ife_decode(struct sk_buff *skb, u16 *metalen) int total_pull; u16 ifehdrln; + if (!pskb_may_pull(skb, skb->dev->hard_header_len + IFE_METAHDRLEN)) + return NULL; + ifehdr = (struct ifeheadr *) (skb->data + skb->dev->hard_header_len); ifehdrln = ntohs(ifehdr->metalen); total_pull = skb->dev->hard_header_len + ifehdrln;