On Thu, Apr 11, 2024 at 10:34 AM 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. 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 > >
