From: Lucas Alvares Gomes <[email protected]> In order to PXE boot a baremetal server using the OVN DHCP server we need to allow users to set the "next-server" (siaddr) [0] field in the DHCP header.
While investigating this issue by comparing the DHCPOFFER and DHCPACK packets sent my dnsmasq and OVN we saw that the "next-server" field was the problem for OVN, without it PXE booting was timing out while fetching the iPXE image from the TFTP server (see the bugzilla ticket below for reference). To confirm this problem we created a bogus patch hardcoding the TFTP address in the siaddr of the DHCP header (see the discussion in the maillist below) and with this in place we were able to deploy a baremetal node using the OVN DHCP end-to-end. This patch is a proper implementation that creates a new DHCP configuration option called "next_server" to allow users to set this field dynamically. This patch uses the DHCP code 253 which is a unsed code for DHCP specification as this is not a normal DHCP option but a special use case in OVN. [0] https://github.com/openvswitch/ovs/blob/9dd3031d2e0e9597449e95428320ccaaff7d8b3d/lib/dhcp.h#L42 Reported-by: https://bugzilla.redhat.com/show_bug.cgi?id=2083629 Reported-by: https://mail.openvswitch.org/pipermail/ovs-discuss/2022-May/051821.html Signed-off-by: Lucas Alvares Gomes <[email protected]> --- controller/pinctrl.c | 69 ++++++++++++++++++++++++++++++-------------- lib/actions.c | 13 ++++++++- lib/ovn-l7.h | 8 +++++ northd/ovn-northd.c | 1 + ovn-nb.xml | 7 +++++ tests/ovn.at | 6 ++-- tests/test-ovn.c | 1 + 7 files changed, 80 insertions(+), 25 deletions(-) diff --git a/controller/pinctrl.c b/controller/pinctrl.c index ae3da332c..428863293 100644 --- a/controller/pinctrl.c +++ b/controller/pinctrl.c @@ -2203,30 +2203,56 @@ pinctrl_handle_put_dhcp_opts( *| 4 Bytes padding | 1 Byte (option end 0xFF ) | 4 Bytes padding| * -------------------------------------------------------------- */ - struct dhcp_opt_header *in_dhcp_opt = - (struct dhcp_opt_header *)reply_dhcp_opts_ptr->data; - if (in_dhcp_opt->code == DHCP_OPT_BOOTFILE_CODE) { - unsigned char *ptr = (unsigned char *)in_dhcp_opt; - int len = sizeof *in_dhcp_opt + in_dhcp_opt->len; - struct dhcp_opt_header *next_dhcp_opt = - (struct dhcp_opt_header *)(ptr + len); - - if (next_dhcp_opt->code == DHCP_OPT_BOOTFILE_ALT_CODE) { - if (!ipxe_req) { - ofpbuf_pull(reply_dhcp_opts_ptr, len); - next_dhcp_opt->code = DHCP_OPT_BOOTFILE_CODE; - } else { - char *buf = xmalloc(len); + ovs_be32 next_server = in_dhcp_data->siaddr; + bool bootfile_name_set = false; + in_dhcp_ptr = reply_dhcp_opts_ptr->data; + end = (const char *)reply_dhcp_opts_ptr->data + reply_dhcp_opts_ptr->size; + + while (in_dhcp_ptr < end) { + struct dhcp_opt_header *in_dhcp_opt = + (struct dhcp_opt_header *)in_dhcp_ptr; + + switch (in_dhcp_opt->code) { + case DHCP_OPT_NEXT_SERVER_CODE: + next_server = get_unaligned_be32(DHCP_OPT_PAYLOAD(in_dhcp_opt)); + break; + case DHCP_OPT_BOOTFILE_CODE: ; + unsigned char *ptr = (unsigned char *)in_dhcp_opt; + int len = sizeof *in_dhcp_opt + in_dhcp_opt->len; + struct dhcp_opt_header *next_dhcp_opt = + (struct dhcp_opt_header *)(ptr + len); + + if (next_dhcp_opt->code == DHCP_OPT_BOOTFILE_ALT_CODE) { + if (!ipxe_req) { + ofpbuf_pull(reply_dhcp_opts_ptr, len); + next_dhcp_opt->code = DHCP_OPT_BOOTFILE_CODE; + } else { + char *buf = xmalloc(len); - memcpy(buf, in_dhcp_opt, len); - ofpbuf_pull(reply_dhcp_opts_ptr, - sizeof *in_dhcp_opt + next_dhcp_opt->len); - memcpy(reply_dhcp_opts_ptr->data, buf, len); - free(buf); + memcpy(buf, in_dhcp_opt, len); + ofpbuf_pull(reply_dhcp_opts_ptr, + sizeof *in_dhcp_opt + next_dhcp_opt->len); + memcpy(reply_dhcp_opts_ptr->data, buf, len); + free(buf); + } + } + bootfile_name_set = true; + break; + case DHCP_OPT_BOOTFILE_ALT_CODE: + if (!bootfile_name_set) { + in_dhcp_opt->code = DHCP_OPT_BOOTFILE_CODE; } + break; + } + + in_dhcp_ptr += sizeof *in_dhcp_opt; + if (in_dhcp_ptr > end) { + break; + } + in_dhcp_ptr += in_dhcp_opt->len; + if (in_dhcp_ptr > end) { + break; } - } else if (in_dhcp_opt->code == DHCP_OPT_BOOTFILE_ALT_CODE) { - in_dhcp_opt->code = DHCP_OPT_BOOTFILE_CODE; } uint16_t new_l4_size = UDP_HEADER_LEN + DHCP_HEADER_LEN + 16; @@ -2259,6 +2285,7 @@ pinctrl_handle_put_dhcp_opts( if (*in_dhcp_msg_type != OVN_DHCP_MSG_INFORM) { dhcp_data->yiaddr = (msg_type == DHCP_MSG_NAK) ? 0 : *offer_ip; + dhcp_data->siaddr = (msg_type == DHCP_MSG_NAK) ? 0 : next_server; } else { dhcp_data->yiaddr = 0; } diff --git a/lib/actions.c b/lib/actions.c index a3cf747db..11b349368 100644 --- a/lib/actions.c +++ b/lib/actions.c @@ -2862,10 +2862,21 @@ encode_PUT_DHCPV4_OPTS(const struct ovnact_put_opts *pdo, opt_header[1] = strlen(c->string); ofpbuf_put(ofpacts, c->string, opt_header[1]); } + /* Encode next_server opt (253) */ + const struct ovnact_gen_option *next_server_opt = find_opt( + pdo->options, pdo->n_options, DHCP_OPT_NEXT_SERVER_CODE); + if (next_server_opt) { + uint8_t *opt_header = ofpbuf_put_zeros(ofpacts, 2); + const union expr_constant *c = next_server_opt->value.values; + opt_header[0] = next_server_opt->option->code; + opt_header[1] = sizeof(ovs_be32); + ofpbuf_put(ofpacts, &c->value.ipv4, sizeof(ovs_be32)); + } for (size_t i = 0; i < pdo->n_options; i++) { const struct ovnact_gen_option *o = &pdo->options[i]; - if (o != offerip_opt && o != boot_opt && o != boot_alt_opt) { + if (o != offerip_opt && o != boot_opt && o != boot_alt_opt && \ + o != next_server_opt) { encode_put_dhcpv4_option(o, ofpacts); } } diff --git a/lib/ovn-l7.h b/lib/ovn-l7.h index 49ecea81f..0b2da9f7b 100644 --- a/lib/ovn-l7.h +++ b/lib/ovn-l7.h @@ -145,6 +145,14 @@ struct gen_opts_map { #define DHCP_OPT_TCP_KEEPALIVE_INTERVAL \ DHCP_OPTION("tcp_keepalive_interval", 38, "uint32") +/* Use unused 253 option for DHCP next-server DHCP option. + * This option is used for setting the "Next server IP address" + * field in the DHCP header. + */ +#define DHCP_OPT_NEXT_SERVER_CODE 253 +#define DHCP_OPT_NEXT_SERVER \ + DHCP_OPTION("next_server", DHCP_OPT_NEXT_SERVER_CODE, "ipv4") + static inline uint32_t gen_opt_hash(char *opt_name) { diff --git a/northd/ovn-northd.c b/northd/ovn-northd.c index 0a0f85010..6e01679e1 100644 --- a/northd/ovn-northd.c +++ b/northd/ovn-northd.c @@ -246,6 +246,7 @@ static struct gen_opts_map supported_dhcp_opts[] = { DHCP_OPT_BROADCAST_ADDRESS, DHCP_OPT_NETBIOS_NAME_SERVER, DHCP_OPT_NETBIOS_NODE_TYPE, + DHCP_OPT_NEXT_SERVER, }; static struct gen_opts_map supported_dhcpv6_opts[] = { diff --git a/ovn-nb.xml b/ovn-nb.xml index 9010240a8..a9c784865 100644 --- a/ovn-nb.xml +++ b/ovn-nb.xml @@ -3579,6 +3579,13 @@ </p> </column> + <column name="options" key="next_server"> + <p> + The DHCPv4 option code for setting the "Next server IP + address" field in the DHCP header. + </p> + </column> + </group> <group title="Boolean DHCP Options"> diff --git a/tests/ovn.at b/tests/ovn.at index 799a6aabd..17a8b7d31 100644 --- a/tests/ovn.at +++ b/tests/ovn.at @@ -1438,9 +1438,9 @@ reg0[0] = lookup_arp_ip(inport, eth.dst); # put_dhcp_opts reg1[0] = put_dhcp_opts(offerip = 1.2.3.4, router = 10.0.0.1); encodes as controller(userdata=00.00.00.02.00.00.00.00.00.01.de.10.00.00.00.40.01.02.03.04.03.04.0a.00.00.01,pause) -reg2[5] = put_dhcp_opts(offerip=10.0.0.4,router=10.0.0.1,netmask=255.255.254.0,mtu=1400,domain_name="ovn.org",wpad="https://example.org",bootfile_name="https://127.0.0.1/boot.ipxe",path_prefix="/tftpboot";); - formats as reg2[5] = put_dhcp_opts(offerip = 10.0.0.4, router = 10.0.0.1, netmask = 255.255.254.0, mtu = 1400, domain_name = "ovn.org", wpad = "https://example.org";, bootfile_name = "https://127.0.0.1/boot.ipxe";, path_prefix = "/tftpboot"); - encodes as controller(userdata=00.00.00.02.00.00.00.00.00.01.de.10.00.00.00.25.0a.00.00.04.43.1b.68.74.74.70.73.3a.2f.2f.31.32.37.2e.30.2e.30.2e.31.2f.62.6f.6f.74.2e.69.70.78.65.03.04.0a.00.00.01.01.04.ff.ff.fe.00.1a.02.05.78.0f.07.6f.76.6e.2e.6f.72.67.fc.13.68.74.74.70.73.3a.2f.2f.65.78.61.6d.70.6c.65.2e.6f.72.67.d2.09.2f.74.66.74.70.62.6f.6f.74,pause) +reg2[5] = put_dhcp_opts(offerip=10.0.0.4,router=10.0.0.1,netmask=255.255.254.0,mtu=1400,domain_name="ovn.org",wpad="https://example.org",bootfile_name="https://127.0.0.1/boot.ipxe",path_prefix="/tftpboot";, next_server=10.0.0.9); + formats as reg2[5] = put_dhcp_opts(offerip = 10.0.0.4, router = 10.0.0.1, netmask = 255.255.254.0, mtu = 1400, domain_name = "ovn.org", wpad = "https://example.org";, bootfile_name = "https://127.0.0.1/boot.ipxe";, path_prefix = "/tftpboot", next_server = 10.0.0.9); + encodes as controller(userdata=00.00.00.02.00.00.00.00.00.01.de.10.00.00.00.25.0a.00.00.04.43.1b.68.74.74.70.73.3a.2f.2f.31.32.37.2e.30.2e.30.2e.31.2f.62.6f.6f.74.2e.69.70.78.65.fd.04.0a.00.00.09.03.04.0a.00.00.01.01.04.ff.ff.fe.00.1a.02.05.78.0f.07.6f.76.6e.2e.6f.72.67.fc.13.68.74.74.70.73.3a.2f.2f.65.78.61.6d.70.6c.65.2e.6f.72.67.d2.09.2f.74.66.74.70.62.6f.6f.74,pause) reg0[15] = put_dhcp_opts(offerip=10.0.0.4,router=10.0.0.1,netmask=255.255.255.0,mtu=1400,ip_forward_enable=1,default_ttl=121,dns_server={8.8.8.8,7.7.7.7},classless_static_route={30.0.0.0/24,10.0.0.4,40.0.0.0/16,10.0.0.6,0.0.0.0/0,10.0.0.1},ethernet_encap=1,router_discovery=0,tftp_server_address={10.0.0.4,10.0.0.5},arp_cache_timeout=10,tcp_keepalive_interval=10); formats as reg0[15] = put_dhcp_opts(offerip = 10.0.0.4, router = 10.0.0.1, netmask = 255.255.255.0, mtu = 1400, ip_forward_enable = 1, default_ttl = 121, dns_server = {8.8.8.8, 7.7.7.7}, classless_static_route = {30.0.0.0/24, 10.0.0.4, 40.0.0.0/16, 10.0.0.6, 0.0.0.0/0, 10.0.0.1}, ethernet_encap = 1, router_discovery = 0, tftp_server_address = {10.0.0.4, 10.0.0.5}, arp_cache_timeout = 10, tcp_keepalive_interval = 10); encodes as controller(userdata=00.00.00.02.00.00.00.00.00.01.de.10.00.00.00.6f.0a.00.00.04.03.04.0a.00.00.01.01.04.ff.ff.ff.00.1a.02.05.78.13.01.01.17.01.79.06.08.08.08.08.08.07.07.07.07.79.14.18.1e.00.00.0a.00.00.04.10.28.00.0a.00.00.06.00.0a.00.00.01.24.01.01.1f.01.00.96.08.0a.00.00.04.0a.00.00.05.23.04.00.00.00.0a.26.04.00.00.00.0a,pause) diff --git a/tests/test-ovn.c b/tests/test-ovn.c index d79c6a5bc..844905797 100644 --- a/tests/test-ovn.c +++ b/tests/test-ovn.c @@ -196,6 +196,7 @@ create_gen_opts(struct hmap *dhcp_opts, struct hmap *dhcpv6_opts, dhcp_opt_add(dhcp_opts, "broadcast_address", 28, "ipv4"); dhcp_opt_add(dhcp_opts, "netbios_name_server", 44, "ipv4"); dhcp_opt_add(dhcp_opts, "netbios_node_type", 46, "uint8"); + dhcp_opt_add(dhcp_opts, "next_server", 253, "ipv4"); /* DHCPv6 options. */ hmap_init(dhcpv6_opts); -- 2.36.1 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
