Thanks for filing this bug, and the excellent analysis. So it looks like the dnsmasq change was introduced here: https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=744231d99505cdead314d13506b5ff8c44a13088
That was in response to this mailing list discussion: https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2023q4/017333.html I think we need to report this issue upstream, perhaps we can revert that commit in the meantime. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to dnsmasq in Ubuntu. https://bugs.launchpad.net/bugs/2055776 Title: After updating ubuntu, the network to which the subnet address is assigned does not become active in KVM. Status in dnsmasq package in Ubuntu: New Bug description: phenomenon: After updating ubuntu, the network to which the subnet address is assigned does not become active in KVM. Cause: This is because the following dnsmasq update operation performed by apt's automatic update causes an error. It worked properly with dnsmasq 2.80, but does not work properly with 2.90. $ cat /var/log/apt/history.log (snip) Start-Date: 2024-02-27 06:17:31 Commandline: /usr/bin/unattended-upgrade Upgrade: dnsmasq-base:amd64 (2.80-1.1ubuntu1.7, 2.90-0ubuntu0.20.04.1) End-Date: 2024-02-27 06:17:44 (snip) $ Cause details: As a premise, bind-dynamic is set in the dnsmasq config file for KVM. Below is an example. $ cat default.conf ##WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE ##OVERWRITTEN AND LOST. Changes to this configuration should be made using: ## virsh net-edit default ## or other application using the libvirt API. ## ## dnsmasq conf file created by libvirt strict-order user=libvirt-dnsmasq pid-file=/run/libvirt/network/default.pid except-interface=lo bind-dynamic interface=virbr0 dhcp-range=192.168.122.2,192.168.122.254,255.255.255.0 dhcp-no-override dhcp-authoritative dhcp-lease-max=253 dhcp-hostsfile=/var/lib/libvirt/dnsmasq/default.hostsfile addn-hosts=/var/lib/libvirt/dnsmasq/default.addnhosts $ When starting the network with KVM (virsh net-start), dnsmasq started from KVM executes the make_sock function twice as shown below. $ cat network.c (snip) 1087 static struct listener *create_listeners(union mysockaddr *addr, int do_ 1087 tftp, int dienow) 1088 { 1089 struct listener *l = NULL; 1090 int fd = -1, tcpfd = -1, tftpfd = -1; 1091 1092 (void)do_tftp; 1093 1094 if (daemon->port != 0) 1095 { 1096 fd = make_sock(addr, SOCK_DGRAM, dienow); 1097 tcpfd = make_sock(addr, SOCK_STREAM, dienow); 1098 } (snip) The following code causes an issue with the update made in dnsmasq 2.90. $ cat network.c (snip) 895 static int make_sock(union mysockaddr *addr, int type, int dienow) 896 { (snip) 934 if (!option_bool(OPT_CLEVERBIND) || errno != EADDRNOTAVAIL) 935 { 936 if (dienow) 937 die(s, daemon->addrbuff, EC_BADNET); 938 else 939 my_syslog(LOG_WARNING, s, daemon->addrbuff, strerror(errno)) 939 ; 940 } (snip) function "make_sock" in network.c:1096 binds the socket to 192.168.122.1/24, and then make_sock in network.c:1097 tries to bind to the same address. However, in network.c:934, when errno==98 occurs, network.c:937 is executed, so dnsmasq does not cause a startup error. As a result, virsh net-start fails. As a temporary workaround, it will work if you try not to die. $ diff -u network_c_back network.c --- network_c_back 2024-02-29 15:36:05.156467935 +0000 +++ network.c 2024-02-29 15:36:38.733324350 +0000 @@ -934,7 +934,8 @@ if (!option_bool(OPT_CLEVERBIND) || errno != EADDRNOTAVAIL) { if (dienow) - die(s, daemon->addrbuff, EC_BADNET); + my_syslog(LOG_WARNING, s, daemon->addrbuff, strerror(errno)); + //die(s, daemon->addrbuff, EC_BADNET); else my_syslog(LOG_WARNING, s, daemon->addrbuff, strerror(errno)); } $ If bind-dynamic is set, it should be modified so that it works even if errno==98. For reference, in the case of dnsmasq 2.80, the code is as follows, so no error occurs. network.c 699 static int make_sock(union mysockaddr *addr, int type, int dienow) 700 { 701 int family = addr->sa.sa_family; 702 int fd, rc, opt = 1; (snip) 715 err: 716 errsave = errno; 717 port = prettyprint_addr(addr, daemon->addrbuff); 718 if (!option_bool(OPT_NOWILD) && !option_bool(OPT_CLEVERBIND)) 719 sprintf(daemon->addrbuff, "port %d", port); 720 s = _("failed to create listening socket for %s: %s"); 721 722 if (fd != -1) 723 close (fd); 724 725 errno = errsave; 726 727 if (dienow) 728 { 729 /* failure to bind addresses given by --listen-address at this 729 point 730 is OK if we're doing bind-dynamic */ 731 if (!option_bool(OPT_CLEVERBIND)) 732 die(s, daemon->addrbuff, EC_BADNET); 733 } 734 else 735 my_syslog(LOG_WARNING, s, daemon->addrbuff, strerror(errno)); 736 737 return -1; 738 } If bind-dynamic is set (option_bool(OPT_CLEVERBIND)==true), it will not die. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/2055776/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
