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Subject[PATCH net-next v3 3/3] net: icmp: add reasons of the skb drops to icmp protocol
Date
From: Menglong Dong <imagedong@tencent.com>

Replace kfree_skb() used in icmp_rcv() and icmpv6_rcv() with
kfree_skb_reason().

In order to get the reasons of the skb drops after icmp message handle,
we change the return type of 'handler()' in 'struct icmp_control' from
'bool' to 'enum skb_drop_reason'. This may change its original
intention, as 'false' means failure, but 'SKB_NOT_DROPPED_YET' means
success now. Therefore, all 'handler' and the call of them need to be
handled. Following 'handler' functions are involved:

icmp_unreach()
icmp_redirect()
icmp_echo()
icmp_timestamp()
icmp_discard()

And following new drop reasons are added:

SKB_DROP_REASON_ICMP_CSUM
SKB_DROP_REASON_ICMP_TYPE
SKB_DROP_REASON_ICMP_BROADCAST

Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
include/linux/skbuff.h | 5 +++
include/net/ping.h | 2 +-
include/trace/events/skb.h | 3 ++
net/ipv4/icmp.c | 75 ++++++++++++++++++++++----------------
net/ipv4/ping.c | 14 ++++---
net/ipv6/icmp.c | 24 +++++++-----
6 files changed, 76 insertions(+), 47 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 26538ceb4b01..18c678b340d3 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -444,6 +444,11 @@ enum skb_drop_reason {
SKB_DROP_REASON_TAP_TXFILTER, /* dropped by tx filter implemented
* at tun/tap, e.g., check_filter()
*/
+ SKB_DROP_REASON_ICMP_CSUM, /* ICMP checksum error */
+ SKB_DROP_REASON_ICMP_TYPE, /* unknown ICMP type */
+ SKB_DROP_REASON_ICMP_BROADCAST, /* unacceptable broadcast(multicast)
+ * ICMP message
+ */
SKB_DROP_REASON_MAX,
};

diff --git a/include/net/ping.h b/include/net/ping.h
index 2fe78874318c..b68fbfdb606f 100644
--- a/include/net/ping.h
+++ b/include/net/ping.h
@@ -76,7 +76,7 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
int ping_common_sendmsg(int family, struct msghdr *msg, size_t len,
void *user_icmph, size_t icmph_len);
int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
-bool ping_rcv(struct sk_buff *skb);
+enum skb_drop_reason ping_rcv(struct sk_buff *skb);

#ifdef CONFIG_PROC_FS
void *ping_seq_start(struct seq_file *seq, loff_t *pos, sa_family_t family);
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index e1670e1e4934..70d0dac8e08b 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -61,6 +61,9 @@
EM(SKB_DROP_REASON_HDR_TRUNC, HDR_TRUNC) \
EM(SKB_DROP_REASON_TAP_FILTER, TAP_FILTER) \
EM(SKB_DROP_REASON_TAP_TXFILTER, TAP_TXFILTER) \
+ EM(SKB_DROP_REASON_ICMP_CSUM, ICMP_CSUM) \
+ EM(SKB_DROP_REASON_ICMP_TYPE, ICMP_TYPE) \
+ EM(SKB_DROP_REASON_ICMP_BROADCAST, ICMP_BROADCAST) \
EMe(SKB_DROP_REASON_MAX, MAX)

#undef EM
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 72a375c7f417..97e53f86b14b 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -186,7 +186,7 @@ EXPORT_SYMBOL(icmp_err_convert);
*/

struct icmp_control {
- bool (*handler)(struct sk_buff *skb);
+ enum skb_drop_reason (*handler)(struct sk_buff *skb);
short error; /* This ICMP is classed as an error message */
};

@@ -839,8 +839,9 @@ static bool icmp_tag_validation(int proto)
* ICMP_PARAMETERPROB.
*/

-static bool icmp_unreach(struct sk_buff *skb)
+static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
{
+ enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
const struct iphdr *iph;
struct icmphdr *icmph;
struct net *net;
@@ -860,8 +861,10 @@ static bool icmp_unreach(struct sk_buff *skb)
icmph = icmp_hdr(skb);
iph = (const struct iphdr *)skb->data;

- if (iph->ihl < 5) /* Mangled header, drop. */
+ if (iph->ihl < 5) { /* Mangled header, drop. */
+ reason = SKB_DROP_REASON_IP_INHDR;
goto out_err;
+ }

switch (icmph->type) {
case ICMP_DEST_UNREACH:
@@ -941,10 +944,10 @@ static bool icmp_unreach(struct sk_buff *skb)
icmp_socket_deliver(skb, info);

out:
- return true;
+ return reason;
out_err:
__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
- return false;
+ return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
}


@@ -952,20 +955,20 @@ static bool icmp_unreach(struct sk_buff *skb)
* Handle ICMP_REDIRECT.
*/

-static bool icmp_redirect(struct sk_buff *skb)
+static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
{
if (skb->len < sizeof(struct iphdr)) {
__ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
- return false;
+ return SKB_DROP_REASON_PKT_TOO_SMALL;
}

if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
/* there aught to be a stat */
- return false;
+ return SKB_DROP_REASON_NOMEM;
}

icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
- return true;
+ return SKB_NOT_DROPPED_YET;
}

/*
@@ -982,7 +985,7 @@ static bool icmp_redirect(struct sk_buff *skb)
* See also WRT handling of options once they are done and working.
*/

-static bool icmp_echo(struct sk_buff *skb)
+static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
{
struct icmp_bxm icmp_param;
struct net *net;
@@ -990,7 +993,7 @@ static bool icmp_echo(struct sk_buff *skb)
net = dev_net(skb_dst(skb)->dev);
/* should there be an ICMP stat for ignored echos? */
if (net->ipv4.sysctl_icmp_echo_ignore_all)
- return true;
+ return SKB_NOT_DROPPED_YET;

icmp_param.data.icmph = *icmp_hdr(skb);
icmp_param.skb = skb;
@@ -1001,10 +1004,10 @@ static bool icmp_echo(struct sk_buff *skb)
if (icmp_param.data.icmph.type == ICMP_ECHO)
icmp_param.data.icmph.type = ICMP_ECHOREPLY;
else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
- return true;
+ return SKB_NOT_DROPPED_YET;

icmp_reply(&icmp_param, skb);
- return true;
+ return SKB_NOT_DROPPED_YET;
}

/* Helper for icmp_echo and icmpv6_echo_reply.
@@ -1122,7 +1125,7 @@ EXPORT_SYMBOL_GPL(icmp_build_probe);
* MUST be accurate to a few minutes.
* MUST be updated at least at 15Hz.
*/
-static bool icmp_timestamp(struct sk_buff *skb)
+static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
{
struct icmp_bxm icmp_param;
/*
@@ -1147,17 +1150,17 @@ static bool icmp_timestamp(struct sk_buff *skb)
icmp_param.data_len = 0;
icmp_param.head_len = sizeof(struct icmphdr) + 12;
icmp_reply(&icmp_param, skb);
- return true;
+ return SKB_NOT_DROPPED_YET;

out_err:
__ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
- return false;
+ return SKB_DROP_REASON_PKT_TOO_SMALL;
}

-static bool icmp_discard(struct sk_buff *skb)
+static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
{
/* pretend it was a success */
- return true;
+ return SKB_NOT_DROPPED_YET;
}

/*
@@ -1165,18 +1168,20 @@ static bool icmp_discard(struct sk_buff *skb)
*/
int icmp_rcv(struct sk_buff *skb)
{
- struct icmphdr *icmph;
+ enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
struct rtable *rt = skb_rtable(skb);
struct net *net = dev_net(rt->dst.dev);
- bool success;
+ struct icmphdr *icmph;

if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
struct sec_path *sp = skb_sec_path(skb);
int nh;

if (!(sp && sp->xvec[sp->len - 1]->props.flags &
- XFRM_STATE_ICMP))
+ XFRM_STATE_ICMP)) {
+ reason = SKB_DROP_REASON_XFRM_POLICY;
goto drop;
+ }

if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
goto drop;
@@ -1184,8 +1189,11 @@ int icmp_rcv(struct sk_buff *skb)
nh = skb_network_offset(skb);
skb_set_network_header(skb, sizeof(*icmph));

- if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
+ if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
+ skb)) {
+ reason = SKB_DROP_REASON_XFRM_POLICY;
goto drop;
+ }

skb_set_network_header(skb, nh);
}
@@ -1207,13 +1215,13 @@ int icmp_rcv(struct sk_buff *skb)
/* We can't use icmp_pointers[].handler() because it is an array of
* size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
*/
- success = icmp_echo(skb);
- goto success_check;
+ reason = icmp_echo(skb);
+ goto reason_check;
}

if (icmph->type == ICMP_EXT_ECHOREPLY) {
- success = ping_rcv(skb);
- goto success_check;
+ reason = ping_rcv(skb);
+ goto reason_check;
}

/*
@@ -1222,8 +1230,10 @@ int icmp_rcv(struct sk_buff *skb)
* RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
* discarded.
*/
- if (icmph->type > NR_ICMP_TYPES)
+ if (icmph->type > NR_ICMP_TYPES) {
+ reason = SKB_DROP_REASON_ICMP_TYPE;
goto error;
+ }

/*
* Parse the ICMP message
@@ -1239,27 +1249,30 @@ int icmp_rcv(struct sk_buff *skb)
if ((icmph->type == ICMP_ECHO ||
icmph->type == ICMP_TIMESTAMP) &&
net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
+ reason = SKB_DROP_REASON_ICMP_BROADCAST;
goto error;
}
if (icmph->type != ICMP_ECHO &&
icmph->type != ICMP_TIMESTAMP &&
icmph->type != ICMP_ADDRESS &&
icmph->type != ICMP_ADDRESSREPLY) {
+ reason = SKB_DROP_REASON_ICMP_BROADCAST;
goto error;
}
}

- success = icmp_pointers[icmph->type].handler(skb);
-success_check:
- if (success) {
+ reason = icmp_pointers[icmph->type].handler(skb);
+reason_check:
+ if (!reason) {
consume_skb(skb);
return NET_RX_SUCCESS;
}

drop:
- kfree_skb(skb);
+ kfree_skb_reason(skb, reason);
return NET_RX_DROP;
csum_error:
+ reason = SKB_DROP_REASON_ICMP_CSUM;
__ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
error:
__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 9a1ea6c263f8..4137e5808107 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -960,12 +960,12 @@ EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);
* All we need to do is get the socket.
*/

-bool ping_rcv(struct sk_buff *skb)
+enum skb_drop_reason ping_rcv(struct sk_buff *skb)
{
+ enum skb_drop_reason reason = SKB_DROP_REASON_NO_SOCKET;
struct sock *sk;
struct net *net = dev_net(skb->dev);
struct icmphdr *icmph = icmp_hdr(skb);
- bool rc = false;

/* We assume the packet has already been checked by icmp_rcv */

@@ -980,15 +980,17 @@ bool ping_rcv(struct sk_buff *skb)
struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

pr_debug("rcv on socket %p\n", sk);
- if (skb2 && !ping_queue_rcv_skb(sk, skb2))
- rc = true;
+ if (skb2)
+ reason = __ping_queue_rcv_skb(sk, skb2);
+ else
+ reason = SKB_DROP_REASON_NOMEM;
sock_put(sk);
}

- if (!rc)
+ if (reason)
pr_debug("no socket, dropping\n");

- return rc;
+ return reason;
}
EXPORT_SYMBOL_GPL(ping_rcv);

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index e6b978ea0e87..01c8003c9fc9 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -864,21 +864,23 @@ void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)

static int icmpv6_rcv(struct sk_buff *skb)
{
+ enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
struct net *net = dev_net(skb->dev);
struct net_device *dev = icmp6_dev(skb);
struct inet6_dev *idev = __in6_dev_get(dev);
const struct in6_addr *saddr, *daddr;
struct icmp6hdr *hdr;
u8 type;
- bool success = false;

if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
struct sec_path *sp = skb_sec_path(skb);
int nh;

if (!(sp && sp->xvec[sp->len - 1]->props.flags &
- XFRM_STATE_ICMP))
+ XFRM_STATE_ICMP)) {
+ reason = SKB_DROP_REASON_XFRM_POLICY;
goto drop_no_count;
+ }

if (!pskb_may_pull(skb, sizeof(*hdr) + sizeof(struct ipv6hdr)))
goto drop_no_count;
@@ -886,8 +888,11 @@ static int icmpv6_rcv(struct sk_buff *skb)
nh = skb_network_offset(skb);
skb_set_network_header(skb, sizeof(*hdr));

- if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
+ if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN,
+ skb)) {
+ reason = SKB_DROP_REASON_XFRM_POLICY;
goto drop_no_count;
+ }

skb_set_network_header(skb, nh);
}
@@ -924,11 +929,11 @@ static int icmpv6_rcv(struct sk_buff *skb)
break;

case ICMPV6_ECHO_REPLY:
- success = ping_rcv(skb);
+ reason = ping_rcv(skb);
break;

case ICMPV6_EXT_ECHO_REPLY:
- success = ping_rcv(skb);
+ reason = ping_rcv(skb);
break;

case ICMPV6_PKT_TOOBIG:
@@ -994,19 +999,20 @@ static int icmpv6_rcv(struct sk_buff *skb)
/* until the v6 path can be better sorted assume failure and
* preserve the status quo behaviour for the rest of the paths to here
*/
- if (success)
- consume_skb(skb);
+ if (reason)
+ kfree_skb_reason(skb, reason);
else
- kfree_skb(skb);
+ consume_skb(skb);

return 0;

csum_error:
+ reason = SKB_DROP_REASON_ICMP_CSUM;
__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_CSUMERRORS);
discard_it:
__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INERRORS);
drop_no_count:
- kfree_skb(skb);
+ kfree_skb_reason(skb, reason);
return 0;
}

--
2.35.1
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