Thanks to Michalis Vasileiadis for spotting this.
print_mac() writes each MAC byte to its output buffer with unbounded
sprintf and is called from main() with pkt.header.hlen straight out
of a BOOTREPLY. hlen is an attacker-controlled uint8_t (up to 255),
each byte expands to up to 3 chars, and the destination is a 500-byte
stack buffer. A malicious leasequery server that echoes the client's
transaction ID and replies with DHCPLEASEACTIVE and an oversized
hlen overflows that stack buffer.
The patch caps len inside print_mac at DHCP_CHADDR_MAX (16), which is
the actual size of chaddr in the BOOTP header and an upper bound on
any legitimate hardware-address length. The other in-file caller of
print_mac already clamps its length argument to 14 before the call,
so this change is local to the vulnerable path.
Error: UNINIT (CWE-457): [#def2]
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release.c:265: var_decl: Declaring variable "ifr" without initializer.
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release.c:285: uninit_use_in_call: Using uninitialized value "ifr". Field "ifr.ifr_ifru" is uninitialized when calling "setsockopt".
# 283| strncpy(ifr.ifr_name, argv[1], sizeof(ifr.ifr_name)-1);
# 284| ifr.ifr_name[sizeof(ifr.ifr_name)-1] = '\0';
# 285|-> if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof(ifr)) == -1)
# 286| {
# 287| perror("cannot setup interface");
Error: CHECKED_RETURN (CWE-252): [#def3]
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:346: check_return: Calling "inet_pton" without checking return value (as is done elsewhere 61 out of 72 times).
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:188: example_assign: Example 1: Assigning: "s" = return value from "inet_pton(10, ip, &result.ip)".
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:189: example_checked: Example 1 (cont.): "s" has its value checked in "s <= 0".
dnsmasq-2.86test7/src/cache.c:1108: example_checked: Example 2: "inet_pton(10, token, &addr)" has its value checked in "inet_pton(10, token, &addr) > 0".
dnsmasq-2.86test7/src/dbus.c:525: example_checked: Example 3: "inet_pton(2, ipaddr, &addr.addr4)" has its value checked in "inet_pton(2, ipaddr, &addr.addr4)".
dnsmasq-2.86test7/src/domain.c:138: example_checked: Example 4: "inet_pton(prot, tail, addr)" has its value checked in "inet_pton(prot, tail, addr)".
dnsmasq-2.86test7/src/lease.c:81: example_checked: Example 5: "inet_pton(10, dnsmasq_daemon->namebuff, &addr.addr6)" has its value checked in "inet_pton(10, dnsmasq_daemon->namebuff, &addr.addr6)".
# 344| client_addr.sin6_flowinfo = 0;
# 345| client_addr.sin6_scope_id =0;
# 346|-> inet_pton(AF_INET6, "::", &client_addr.sin6_addr);
# 347| bind(sock, (struct sockaddr*)&client_addr, sizeof(struct sockaddr_in6));
# 348| inet_pton(AF_INET6, DHCP6_MULTICAST_ADDRESS, &server_addr.sin6_addr);
Error: CHECKED_RETURN (CWE-252): [#def4]
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:347: check_return: Calling "bind(sock, (struct sockaddr *)&client_addr, 28U)" without checking return value. This library function may fail and return an error code.
# 345| client_addr.sin6_scope_id =0;
# 346| inet_pton(AF_INET6, "::", &client_addr.sin6_addr);
# 347|-> bind(sock, (struct sockaddr*)&client_addr, sizeof(struct sockaddr_in6));
# 348| inet_pton(AF_INET6, DHCP6_MULTICAST_ADDRESS, &server_addr.sin6_addr);
# 349| server_addr.sin6_port = htons(DHCP6_SERVER_PORT);
Error: CHECKED_RETURN (CWE-252): [#def5]
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:348: check_return: Calling "inet_pton" without checking return value (as is done elsewhere 61 out of 72 times).
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:188: example_assign: Example 1: Assigning: "s" = return value from "inet_pton(10, ip, &result.ip)".
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:189: example_checked: Example 1 (cont.): "s" has its value checked in "s <= 0".
dnsmasq-2.86test7/src/cache.c:1108: example_checked: Example 2: "inet_pton(10, token, &addr)" has its value checked in "inet_pton(10, token, &addr) > 0".
dnsmasq-2.86test7/src/dbus.c:525: example_checked: Example 3: "inet_pton(2, ipaddr, &addr.addr4)" has its value checked in "inet_pton(2, ipaddr, &addr.addr4)".
dnsmasq-2.86test7/src/domain.c:138: example_checked: Example 4: "inet_pton(prot, tail, addr)" has its value checked in "inet_pton(prot, tail, addr)".
dnsmasq-2.86test7/src/lease.c:81: example_checked: Example 5: "inet_pton(10, dnsmasq_daemon->namebuff, &addr.addr6)" has its value checked in "inet_pton(10, dnsmasq_daemon->namebuff, &addr.addr6)".
# 346| inet_pton(AF_INET6, "::", &client_addr.sin6_addr);
# 347| bind(sock, (struct sockaddr*)&client_addr, sizeof(struct sockaddr_in6));
# 348|-> inet_pton(AF_INET6, DHCP6_MULTICAST_ADDRESS, &server_addr.sin6_addr);
# 349| server_addr.sin6_port = htons(DHCP6_SERVER_PORT);
# 350| int16_t recv_size = 0;
Error: NEGATIVE_RETURNS (CWE-394): [#def6]
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:360: var_tested_neg: Variable "recv_size" tests negative.
dnsmasq-2.86test7/contrib/lease-tools/dhcp_release6.c:373: negative_returns: "recv_size" is passed to a parameter that cannot be negative.
# 371| }
# 372|
# 373|-> int16_t result = parse_packet(response, recv_size);
# 374| if (result == NOT_REPLY_CODE)
# 375| {
Order dnsmasq.service before network.target and after network-online.target & nss-lookup.target. Additionally pull in nss-lookup.target.
This matches the behaviour of systemd-resolved and Unbound.
Signed-off-by: nl6720 <nl6720@gmail.com>
If no IPv4 address is present on given interface, the tool would not
send any request. It would not report any error at the same time. Report
error if request send failed.
Signed-off-by: Petr Mensik <pemensik@redhat.com>
Currently, dhcp_release will only send a 'fake' release
when the address given is in the same subnet as an IP
on the interface that was given.
This doesn't work in an environment where dnsmasq is
managing leases for remote subnets via a DHCP relay, as
running dhcp_release locally will just cause it to
silently exit without doing anything, leaving the lease
in the database.
Change it to use the default IP on the interface, as the
dnsmasq source code at src/dhcp.c does, if no matching subnet
IP is found, as a fall-back. This fixes an issue we are
seeing in certain Openstack deployments where we are using
dnsmasq to provision baremetal systems in a datacenter.
While using Dbus might have seemed like an obvious solution,
because of our extensive use of network namespaces (which
Dbus doesn't support), this seemed like a better solution
than creating system.d policy files for each dnsmasq we
might spawn and using --enable-dbus=$id in order to isolate
messages to specific dnsmasq instances.
Signed-off-by: Brian Haley <haleyb.dev@gmail.com>
Michalis Vasileiadis