On Thu, Apr 11, 2024 at 12:57 PM Peilin He <peilinhe2...@163.com> wrote: > > >> >[...] > >> >> >I think my understanding based on what Eric depicted differs from you: > >> >> >we're supposed to filter out those many invalid cases and only trace > >> >> >the valid action of sending a icmp, so where to add a new tracepoint > >> >> >is important instead of adding more checks in the tracepoint itself. > >> >> >Please refer to what trace_tcp_retransmit_skb() does :) > >> >> > > >> >> >Thanks, > >> >> >Jason > >> >> Okay, thank you for your suggestion. In order to avoid filtering out > >> >> those many invalid cases and only tracing the valid action of sending > >> >> a icmp, the next patch will add udd_fail_no_port trancepoint to the > >> >> include/trace/events/udp.h. This will solve the problem you mentioned > >> >> very well. At this point, only UDP protocol exceptions will be tracked, > >> >> without the need to track them in icmp_send. > >> > > >> >I'm not against what you did (tracing all the icmp_send() for UDP) in > >> >your original patch. I was suggesting that you could put > >> >trace_icmp_send() in the right place, then you don't have to check the > >> >possible error condition (like if the skb->head is valid or not, ...) > >> >in your trace function. > >> > > >> >One example that can avoid various checks existing in the > >> >__icmp_send() function: > >> >diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c > >> >index e63a3bf99617..2c9f7364de45 100644 > >> >--- a/net/ipv4/icmp.c > >> >+++ b/net/ipv4/icmp.c > >> >@@ -767,6 +767,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, > >> >int code, __be32 info, > >> > if (!fl4.saddr) > >> > fl4.saddr = htonl(INADDR_DUMMY); > >> > > >> >+ trace_icmp_send(skb_in, type, code); > >> > icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); > >> > ende > >> > ip_rt_put(rt); > >> > > >> >If we go here, it means we are ready to send the ICMP skb because > >> >we're done extracting the right information in the 'struct sk_buff > >> >skb_in'. Simpler and easier, right? > >> > > >> >Thanks, > >> >Jason > >> > >> I may not fully agree with this viewpoint. When trace_icmp_send is placed > >> in this position, it cannot guarantee that all skbs in icmp are UDP > >> protocols > >> (UDP needs to be distinguished based on the proto_4!=IPPROTO_UDP > >> condition), > >> nor can it guarantee the legitimacy of udphdr (*uh legitimacy check is > >> required). > > > >Of course, the UDP test statement is absolutely needed! Eric > >previously pointed this out in the V1 patch thread. I'm not referring > >to this one but like skb->head check something like this which exists > >in __icmp_send() function. You can see there are so many checks in it > >before sending. > > > >So only keeping the UDP check is enough, I think. > > The __icmp_send function only checks the IP header, but does not check > the UDP header, as shown in the following code snippet: > > if ((u8 *)iph < skb_in->head || > (skb_network_header(skb_in) + sizeof(*iph)) > > skb_tail_pointer(skb_in)) > goto out; > > There is no problem with the IP header check, which does not mean that > the UDP header is correct. Therefore, I believe that it is essential to > include a legitimacy judgment for the UDP header. > > Here is an explanation of this code: > Firstly, the UDP header (*uh) is extracted from the skb. > Then, if the current protocol of the skb is not UDP, or if the address of > uh is outside the range of the skb, the source port and destination port > will not be resolved, and 0 will be filled in directly.Otherwise, > the source port and destination port of the UDP header will be resolved. > > + struct udphdr *uh = udp_hdr(skb); > + if (proto_4 != IPPROTO_UDP || (u8 *)uh < skb->head || > + (u8 *)uh + sizeof(struct udphdr) > skb_tail_pointer(skb)) {
>From the beginning, I always agree with the UDP check. I was saying if you can put the trace_icmp_send() just before icmp_push_reply()[1], you could avoid those kinds of checks. As I said in the previous email, "only keeping the UDP check is enough". So you are right. [1] diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index e63a3bf99617..2c9f7364de45 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -767,6 +767,7 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, if (!fl4.saddr) fl4.saddr = htonl(INADDR_DUMMY); + trace_icmp_send(skb_in, type, code); icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); ende: ip_rt_put(rt); If we're doing this, trace_icmp_send() can reflect the real action of sending an ICMP like trace_tcp_retransmit_skb(). Or else, the trace could print some messages but no real ICMP is sent (see those error checks). WDYT? Thanks, Jason > > With best wishes > Peilin He > > >Thanks, > >Jason > > > >> > >> With best wishes > >> Peilin He > >> > >> >> > >> >> >> 2.Target this patch for net-next. > >> >> >> > >> >> >> v2->v3: > >> >> >> Some fixes according to > >> >> >> https://lore.kernel.org/all/20240319102549.7f7f6...@gandalf.local.home/ > >> >> >> 1. Change the tracking directory to/sys/kernel/tracking. > >> >> >> 2. Adjust the layout of the TP-STRUCT_entry parameter structure. > >> >> >> > >> >> >> v1->v2: > >> >> >> Some fixes according to > >> >> >> https://lore.kernel.org/all/CANn89iL-y9e_VFpdw=3DsZtRnKRu_tnUwqHuFQTJvJsv= > >> >> >-nz1x...@mail.gmail.com/ > >> >> >> 1. adjust the trace_icmp_send() to more protocols than UDP. > >> >> >> 2. move the calling of trace_icmp_send after sanity checks > >> >> >> in __icmp_send(). > >> >> >> > >> >> >> Signed-off-by: Peilin He<he.pei...@zte.com.cn> > >> >> >> Reviewed-by: xu xin <xu.xi...@zte.com.cn> > >> >> >> Reviewed-by: Yunkai Zhang <zhang.yun...@zte.com.cn> > >> >> >> Cc: Yang Yang <yang.yan...@zte.com.cn> > >> >> >> Cc: Liu Chun <liu.ch...@zte.com.cn> > >> >> >> Cc: Xuexin Jiang <jiang.xue...@zte.com.cn> > >> >> >> --- > >> >> >> include/trace/events/icmp.h | 65 > >> >> >> +++++++++++++++++++++++++++++++++++++ > >> >> >> net/ipv4/icmp.c | 4 +++ > >> >> >> 2 files changed, 69 insertions(+) > >> >> >> create mode 100644 include/trace/events/icmp.h > >> >> >> > >> >> >> diff --git a/include/trace/events/icmp.h > >> >> >> b/include/trace/events/icmp.h > >> >> >> new file mode 100644 > >> >> >> index 000000000000..7d5190f48a28 > >> >> >> --- /dev/null > >> >> >> +++ b/include/trace/events/icmp.h > >> >> >> @@ -0,0 +1,65 @@ > >> >> >> +/* SPDX-License-Identifier: GPL-2.0 */ > >> >> >> +#undef TRACE_SYSTEM > >> >> >> +#define TRACE_SYSTEM icmp > >> >> >> + > >> >> >> +#if !defined(_TRACE_ICMP_H) || defined(TRACE_HEADER_MULTI_READ) > >> >> >> +#define _TRACE_ICMP_H > >> >> >> + > >> >> >> +#include <linux/icmp.h> > >> >> >> +#include <linux/tracepoint.h> > >> >> >> + > >> >> >> +TRACE_EVENT(icmp_send, > >> >> >> + > >> >> >> + TP_PROTO(const struct sk_buff *skb, int type, int > >> >> >> code), > >> >> >> + > >> >> >> + TP_ARGS(skb, type, code), > >> >> >> + > >> >> >> + TP_STRUCT__entry( > >> >> >> + __field(const void *, skbaddr) > >> >> >> + __field(int, type) > >> >> >> + __field(int, code) > >> >> >> + __array(__u8, saddr, 4) > >> >> >> + __array(__u8, daddr, 4) > >> >> >> + __field(__u16, sport) > >> >> >> + __field(__u16, dport) > >> >> >> + __field(unsigned short, ulen) > >> >> >> + ), > >> >> >> + > >> >> >> + TP_fast_assign( > >> >> >> + struct iphdr *iph =3D ip_hdr(skb); > >> >> >> + int proto_4 =3D iph->protocol; > >> >> >> + __be32 *p32; > >> >> >> + > >> >> >> + __entry->skbaddr =3D skb; > >> >> >> + __entry->type =3D type; > >> >> >> + __entry->code =3D code; > >> >> >> + > >> >> >> + struct udphdr *uh =3D udp_hdr(skb); > >> >> >> + if (proto_4 !=3D IPPROTO_UDP || (u8 *)uh < > >> >> >> skb->h= > >> >> >ead || > >> >> >> + (u8 *)uh + sizeof(struct udphdr) > > >> >> >> skb_ta= > >> >> >il_pointer(skb)) { > >> >> >> + __entry->sport =3D 0; > >> >> >> + __entry->dport =3D 0; > >> >> >> + __entry->ulen =3D 0; > >> >> >> + } else { > >> >> >> + __entry->sport =3D ntohs(uh->source); > >> >> >> + __entry->dport =3D ntohs(uh->dest); > >> >> >> + __entry->ulen =3D ntohs(uh->len); > >> >> >> + } > >> >> >> + > >> >> >> + p32 =3D (__be32 *) __entry->saddr; > >> >> >> + *p32 =3D iph->saddr; > >> >> >> + > >> >> >> + p32 =3D (__be32 *) __entry->daddr; > >> >> >> + *p32 =3D iph->daddr; > >> >> >> + ), > >> >> >> + > >> >> >> + TP_printk("icmp_send: type=3D%d, code=3D%d. >From > >> >> >> %pI4:%u = > >> >> >to %pI4:%u ulen=3D%d skbaddr=3D%p", > >> >> >> + __entry->type, __entry->code, > >> >> >> + __entry->saddr, __entry->sport, > >> >> >> __entry->daddr, > >> >> >> + __entry->dport, __entry->ulen, > >> >> >> __entry->skbaddr) > >> >> >> +); > >> >> >> + > >> >> >> +#endif /* _TRACE_ICMP_H */ > >> >> >> + > >> >> >> +/* This part must be outside protection */ > >> >> >> +#include <trace/define_trace.h> > >> >> >> \ No newline at end of file > >> >> >> diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c > >> >> >> index 8cebb476b3ab..224551d75c02 100644 > >> >> >> --- a/net/ipv4/icmp.c > >> >> >> +++ b/net/ipv4/icmp.c > >> >> >> @@ -92,6 +92,8 @@ > >> >> >> #include <net/inet_common.h> > >> >> >> #include <net/ip_fib.h> > >> >> >> #include <net/l3mdev.h> > >> >> >> +#define CREATE_TRACE_POINTS > >> >> >> +#include <trace/events/icmp.h> > >> >> >> > >> >> >> /* > >> >> >> * Build xmit assembly blocks > >> >> >> @@ -672,6 +674,8 @@ void __icmp_send(struct sk_buff *skb_in, int > >> >> >> type, in= > >> >> >t code, __be32 info, > >> >> >> } > >> >> >> } > >> >> >> > >> >> >> + trace_icmp_send(skb_in, type, code); > >> >> >> + > >> >> >> /* Needed by both icmp_global_allow and icmp_xmit_lock */ > >> >> >> local_bh_disable(); > >> >> >> > >> >> >> -- > >> >> >> 2.25.1 > >