Public bug reported:
I have an Ubuntu 14.04 host that I am using as both a keepalived/ipvs
loadbalancer and dnsmasq server for pxebooting servers.
After updating linux-image 3.13.0-29.53 -> 3.13.0-32.57 I noticed that
dnsmasq-tftp stopped working. pxeboot clients would hang on the "Loading
..../linux" TFTP transfer, with the transfer stalling roughly ~1000
blocks into the transfer:
10:30:51.011728 IP 10.1.1.2.43540 > 10.1.12.1.49165: UDP, length 1412
10:30:51.011924 IP 10.1.12.1.49165 > 10.1.1.2.43540: UDP, length 4
10:30:51.012012 IP 10.1.1.2.43540 > 10.1.12.1.49165: UDP, length 1412
10:30:51.012183 IP 10.1.12.1.49165 > 10.1.1.2.43540: UDP, length 4
stracing dnsmasq I noticed something very odd: sendto() on the
socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) would suddenly start
persistently returning EPERM in mid-transfer, even when dnsmasq
continued to periodically retry:
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 1 (in [17],
left {0, 249834})
recvfrom(17, "\0\4\3\352", 4096, 0, NULL, NULL) = 4
lseek(16, 1410816, SEEK_SET) = 1410816
read(16,
"\25\306\345f\2{\r\4)W\276\32\336q\252_\230q\213\341U\354\25\374k7\243\32\221X+\v"...,
1408) = 1408
sendto(17,
"\0\3\3\353\25\306\345f\2{\r\4)W\276\32\336q\252_\230q\213\341U\354\25\374k7\243\32"...,
1412, 0, {sa_family=AF_INET, sin_port=htons(49165),
sin_addr=inet_addr("10.1.11.3")}, 16) = 1412
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 1 (in [17],
left {0, 249839})
recvfrom(17, "\0\4\3\353", 4096, 0, NULL, NULL) = 4
lseek(16, 1412224, SEEK_SET) = 1412224
read(16, "*\360
<C\363l\320:\256~\307\236\26P\323\274%\260\362\341&\232\r\243\370\224\277\221\\\307\372"...,
1408) = 1408
sendto(17, "\0\3\3\354*\360
<C\363l\320:\256~\307\236\26P\323\274%\260\362\341&\232\r\243\370\224\277"...,
1412, 0, {sa_family=AF_INET, sin_port=htons(49165),
sin_addr=inet_addr("10.1.11.3")}, 16) = -1 EPERM (Operation not permitted)
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 0 (Timeout)
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 0 (Timeout)
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 0 (Timeout)
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 0 (Timeout)
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 0 (Timeout)
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 0 (Timeout)
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 0 (Timeout)
select(18, [4 5 6 7 8 9 10 11 12 15 17], [], [], {0, 250000}) = 0 (Timeout)
lseek(16, 1412224, SEEK_SET) = 1412224
read(16, "*\360
<C\363l\320:\256~\307\236\26P\323\274%\260\362\341&\232\r\243\370\224\277\221\\\307\372"...,
1408) = 1408
sendto(17, "\0\3\3\354*\360
<C\363l\320:\256~\307\236\26P\323\274%\260\362\341&\232\r\243\370\224\277"...,
1412, 0, {sa_family=AF_INET, sin_port=htons(49165),
sin_addr=inet_addr("10.1.11.3")}, 16) = -1 EPERM (Operation not permitted)
This was with all iptables rules unloaded (so no OUTPUT -j DENY) and
apparmor profiles torn down.
I also noticed the following dmesgs appearing at roughly similar times
to the tftp transfers getting stuck (although not coinciding exactly
with the stall):
[70325.516724] IPv6 header not found
The error pointed to ipvs (which I am using on the same host as an IPv4 NAT
loadbalancer):
http://archive.linuxvirtualserver.org/html/lvs-devel/2012-08/msg00018.html
http://comments.gmane.org/gmane.comp.linux.lvs.devel/3614
I then tore down the ipvs rules (service keepalived stop) and unloaded
the modules (rmmod ip_vs_rr ip_vs), and the issue resolved itself - the
stalled dnsmasq-tftp transfer resumed!
This seems to be reproducible, i.e. modprobing ip_vs and starting
keepalived will cause dnsmasq-tftp to stall again, and
stopping/unloading will resume.
This seems to happen reproducibly on boot with -32 and -30. This does
NOT seem to happen with 3.13.0-29 which I was using up until now.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu)
Importance: Undecided
Status: New
** No longer affects: biosdevname (Ubuntu)
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https://bugs.launchpad.net/bugs/1349768
Title:
kernel 3.13.0-32 ipvs "IPv6 header not found" related to UDP socket
sendto() EPERM errors
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