bgpd: fix no bgp as-path access-list issue #15387

fdumontet6WIND · 2024-02-16T16:28:42Z

router bgp 65001
no bgp ebgp-requires-policy
neighbor 192.168.1.2 remote-as external
neighbor 192.168.1.2 timers 3 10
address-family ipv4 unicast
neighbor 192.168.1.2 route-map r2 in
exit-address-family
!
ip prefix-list p1 seq 5 permit 172.16.255.31/32
!
route-map r2 permit 10
match ip address prefix-list p1
set as-path exclude 65003
route-map r2 permit 20
set as-path exclude all
!

we make the following commands

bgp as-path access-list FIRST permit ^65
bgp as-path access-list SECOND permit 2
route-map r2 permit 6
set as-path exclude as-path-access-list SECOND

and then

no bgp as-path access-list SECOND permit 2
clear bgp *

we have the following crash in bgp

           Stack trace of thread 536083:
            #0  0x00007f87f8aacfe1 raise (libpthread.so.0 + 0x12fe1)
            https://github.com/FRRouting/frr/pull/1  0x00007f87f8cf6870 core_handler (libfrr.so.0 +
	    0xf6870)
            https://github.com/FRRouting/frr/issues/2  0x00007f87f8aad140 __restore_rt (libpthread.so.0 +
	    0x13140)
            https://github.com/FRRouting/frr/issues/3  0x00007f87f89a5122 __GI___regexec (libc.so.6 +
	    0xdf122)
            https://github.com/FRRouting/frr/issues/4  0x000055d7f198b4a7 aspath_filter_exclude_acl (bgpd +
	    0x2054a7)
            https://github.com/FRRouting/frr/pull/5  0x000055d7f1902187 route_set_aspath_exclude (bgpd +
	    0x17c187)
            https://github.com/FRRouting/frr/pull/6  0x00007f87f8ce54b0 route_map_apply_ext (libfrr.so.0
	    + 0xe54b0)
            https://github.com/FRRouting/frr/pull/7  0x000055d7f18da925 bgp_input_modifier (bgpd +
	    0x154925)
            https://github.com/FRRouting/frr/pull/8  0x000055d7f18e0647 bgp_update (bgpd + 0x15a647)
            https://github.com/FRRouting/frr/issues/9  0x000055d7f18e4772 bgp_nlri_parse_ip (bgpd +
	    0x15e772)
            https://github.com/FRRouting/frr/pull/10 0x000055d7f18c38ae bgp_nlri_parse (bgpd + 0x13d8ae)
            https://github.com/FRRouting/frr/issues/11 0x000055d7f18c6b7a bgp_update_receive (bgpd +
	    0x140b7a)
            https://github.com/FRRouting/frr/pull/12 0x000055d7f18c8ff3 bgp_process_packet (bgpd +
	    0x142ff3)
            https://github.com/FRRouting/frr/pull/13 0x00007f87f8d0dce0 thread_call (libfrr.so.0 +
	    0x10dce0)
            https://github.com/FRRouting/frr/issues/14 0x00007f87f8cacb28 frr_run (libfrr.so.0 + 0xacb28)
            https://github.com/FRRouting/frr/pull/15 0x000055d7f18435da main (bgpd + 0xbd5da)
            https://github.com/FRRouting/frr/issues/16 0x00007f87f88e9d0a __libc_start_main (libc.so.6 +
	    0x23d0a)
            https://github.com/FRRouting/frr/issues/17 0x000055d7f18415fa _start (bgpd + 0xbb5fa)

analysis

crash is due to the fact that there were always a pointer from
as-path exclude to deleted as-path access list.

fix
we add a backpointer mechanism to manage the dependency beetween
as-path access-list and aspath exclude.

fdumontet6WIND · 2024-02-17T18:34:30Z

ci:rerun

ton31337

A bit of stuff regarding the naming to address, please.

tests/topotests/bgp_set_aspath_exclude/test_bgp_set_aspath_exclude.py

bgpd/bgp_filter.h

bgpd/bgp_filter.c

ton31337 · 2024-02-18T12:40:11Z

@Mergifyio backport dev/10.0 stable/9.1

mergify · 2024-02-18T12:40:20Z

backport dev/10.0 stable/9.1

✅ Backports have been created

#15435 bgpd: fix no bgp as-path access-list issue (backport #15387) has been created for branch dev/10.0
#15436 bgpd: fix no bgp as-path access-list issue (backport #15387) has been created for branch stable/9.1

bgpd/bgp_routemap.c

pguibert6WIND

additional fix is needed.

pguibert6WIND

lgtm

riw777

looks good

fdumontet6WIND · 2024-02-20T18:15:26Z

ci:rerun

bgpd/bgp_filter.c

bgpd/bgp_filter.h

ton31337

Couple nits yet.

tests/topotests/bgp_set_aspath_exclude/test_bgp_set_aspath_exclude.py

bgpd/bgp_filter.h

bgpd/bgp_routemap.c

ton31337

One grammar (renegotiate), but overall OK 🤷‍♂️

tests/topotests/bgp_set_aspath_exclude/test_bgp_set_aspath_exclude.py

adding a tests about: "no bgp as-path access-list" command. the folloxing "clear bgp *" command leads to the crash exhibited above. a sleep had been added to capture the crash befor the end of scenario. 50 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory. [Current thread is 1 (Thread 0x7f5f05cbb9c0 (LWP 1371086))] (gdb) bt context=0x7ffcf2c216c0) at lib/sigevent.c:248 acl_list=0x55c976ec03c0) at bgpd/bgp_aspath.c:1688 dummy=0x7ffcf2c22340, object=0x7ffcf2c21e70) at bgpd/bgp_routemap.c:2401 match_object=0x7ffcf2c21e70, set_object=0x7ffcf2c21e70, pref=0x0) at lib/routemap.c:2687 attr=0x7ffcf2c220b0, afi=AFI_IP, safi=SAFI_UNICAST, rmap_name=0x0, label=0x0, num_labels=0, dest=0x55c976ebeaf0) at bgpd/bgp_route.c:1807 addpath_id=0, attr=0x7ffcf2c22450, afi=AFI_IP, safi=SAFI_UNICAST, type=10, sub_type=0, prd=0x0, label=0x0, num_labels=0, soft_reconfig=0, evpn=0x0) at bgpd/bgp_route.c:4424 packet=0x7ffcf2c22410) at bgpd/bgp_route.c:6266 packet=0x7ffcf2c22410, mp_withdraw=false) at bgpd/bgp_packet.c:341 peer=0x55c976e89ed0, size=43) at bgpd/bgp_packet.c:2414 at bgpd/bgp_packet.c:3899 Signed-off-by: Francois Dumontet <[email protected]>

router bgp 65001 no bgp ebgp-requires-policy neighbor 192.168.1.2 remote-as external neighbor 192.168.1.2 timers 3 10 address-family ipv4 unicast neighbor 192.168.1.2 route-map r2 in exit-address-family ! ip prefix-list p1 seq 5 permit 172.16.255.31/32 ! route-map r2 permit 10 match ip address prefix-list p1 set as-path exclude 65003 route-map r2 permit 20 set as-path exclude all ! we make the following commands bgp as-path access-list FIRST permit ^65 bgp as-path access-list SECOND permit 2 route-map r2 permit 6 set as-path exclude as-path-access-list SECOND and then no bgp as-path access-list SECOND permit 2 clear bgp * we have the following crash in bgp Stack trace of thread 536083: #0 0x00007f87f8aacfe1 raise (libpthread.so.0 + 0x12fe1) FRRouting#1 0x00007f87f8cf6870 core_handler (libfrr.so.0 + 0xf6870) FRRouting#2 0x00007f87f8aad140 __restore_rt (libpthread.so.0 + 0x13140) FRRouting#3 0x00007f87f89a5122 __GI___regexec (libc.so.6 + 0xdf122) FRRouting#4 0x000055d7f198b4a7 aspath_filter_exclude_acl (bgpd + 0x2054a7) FRRouting#5 0x000055d7f1902187 route_set_aspath_exclude (bgpd + 0x17c187) FRRouting#6 0x00007f87f8ce54b0 route_map_apply_ext (libfrr.so.0 + 0xe54b0) FRRouting#7 0x000055d7f18da925 bgp_input_modifier (bgpd + 0x154925) FRRouting#8 0x000055d7f18e0647 bgp_update (bgpd + 0x15a647) FRRouting#9 0x000055d7f18e4772 bgp_nlri_parse_ip (bgpd + 0x15e772) FRRouting#10 0x000055d7f18c38ae bgp_nlri_parse (bgpd + 0x13d8ae) FRRouting#11 0x000055d7f18c6b7a bgp_update_receive (bgpd + 0x140b7a) FRRouting#12 0x000055d7f18c8ff3 bgp_process_packet (bgpd + 0x142ff3) FRRouting#13 0x00007f87f8d0dce0 thread_call (libfrr.so.0 + 0x10dce0) FRRouting#14 0x00007f87f8cacb28 frr_run (libfrr.so.0 + 0xacb28) FRRouting#15 0x000055d7f18435da main (bgpd + 0xbd5da) FRRouting#16 0x00007f87f88e9d0a __libc_start_main (libc.so.6 + 0x23d0a) FRRouting#17 0x000055d7f18415fa _start (bgpd + 0xbb5fa) analysis crash is due to the fact that there were always a pointer from as-path exclude to deleted as-path access list. fix we add a backpointer mechanism to manage the dependency beetween as-path access-list and aspath exclude. Signed-off-by: Francois Dumontet <[email protected]>

fdumontet6WIND · 2024-02-26T17:34:35Z

failure not linked with pull request
ci:rerun

bgpd: fix no bgp as-path access-list issue (backport #15387)

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This was referenced Feb 27, 2024

bgpd: fix no bgp as-path access-list issue (backport #15387) #15435

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bgpd: fix no bgp as-path access-list issue (backport #15387) #15436

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ton31337 added a commit that referenced this pull request Feb 27, 2024

Merge pull request #15435 from FRRouting/mergify/bp/dev/10.0/pr-15387

1d64549

bgpd: fix no bgp as-path access-list issue (backport #15387)

ton31337 added a commit that referenced this pull request Feb 27, 2024

Merge pull request #15436 from FRRouting/mergify/bp/stable/9.1/pr-15387

8b02d3e

bgpd: fix no bgp as-path access-list issue (backport #15387)

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bgpd: fix no bgp as-path access-list issue #15387

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bgpd: fix no bgp as-path access-list issue #15387

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