discover: Add support for IPMI network override

On BMC platforms the 'Get System Boot Options' command can also be used
to check for a temporary network interface config override. This is
implemented via the optional 'OEM Parameters' field defined in the IPMI
v2 spec. We define the actual format of the field as:
	- 4 byte cookie value
	- 2 byte version value
	- 1 byte hardware address size
	- 1 byte IP address size
	- Hardware address
	- 1 byte flags for 'ignore' and 'method'
	And for static configs:
	- IP Address
	- 1 byte subnet value
	- Gateway address

If set the config override replaces any other interface config, forcing
the use of the specified configuration.

Signed-off-by: Sam Mendoza-Jonas <sam@mendozajonas.com>

3 files changed, 196 insertions, 0 deletions

diff --git a/discover/ipmi.c b/discover/ipmi.c
index f59974a..e52070f 100644
--- a/discover/ipmi.c
+++ b/discover/ipmi.c
@@ -4,6 +4,7 @@
 #include <poll.h>
 #include <string.h>
 #include <unistd.h>
+#include <arpa/inet.h>
 
 #include <sys/ioctl.h>
 #include <sys/time.h>
@@ -220,3 +221,99 @@ bool ipmi_present(void)
 	return !access(ipmi_devnode, R_OK | W_OK);
 }
 
+/* Reads and applies an IPMI interface config override, which closely follows
+ * the format of an interface config struct as described in lib/types */
+void parse_ipmi_interface_override(struct config *config, uint8_t *buf,
+				uint16_t len)
+{
+	struct interface_config *ifconf;
+	char *ipstr, *gatewaystr;
+	uint8_t hwsize, ipsize;
+	int addr_type, i = 0;
+	socklen_t addr_len;
+
+	/* Get 1-byte hardware address size and ip address size */
+	memcpy(&hwsize, &buf[i], sizeof(hwsize));
+	i += sizeof(hwsize);
+	memcpy(&ipsize, &buf[i], sizeof(ipsize));
+	i += sizeof(ipsize);
+
+	if (!hwsize || !ipsize) {
+		pb_log("%s: Empty response\n", __func__);
+		return;
+	}
+
+	/* At the moment only support 6-byte MAC addresses */
+	if (hwsize != sizeof(ifconf->hwaddr)) {
+		pb_log("Unsupported HW address size in network override: %u\n",
+		       hwsize);
+		return;
+	}
+
+	/* Sanity check the IP address size */
+	if (ipsize == 4) {
+		addr_type = AF_INET;
+		addr_len = INET_ADDRSTRLEN;
+	} else if (ipsize == 16) {
+		addr_type = AF_INET6;
+		addr_len = INET6_ADDRSTRLEN;
+	} else {
+		pb_log("Unsupported IP address size: %u\n", ipsize);
+		return;
+	}
+
+	/* Everything past here is the interface config */
+	ifconf = talloc_zero(config, struct interface_config);
+	if (!ifconf) {
+		pb_log("Failed to allocate network override\n");
+		return;
+	}
+
+	/* Hardware Address */
+	memcpy(ifconf->hwaddr, &buf[i], hwsize);
+	i += hwsize;
+
+	/* Check 1-byte ignore and method flags */
+	ifconf->ignore = !!buf[i++];
+	ifconf->method = !!buf[i++];
+
+	if (ifconf->method == CONFIG_METHOD_STATIC) {
+		if (ipsize + ipsize  + 1 > len - i) {
+			pb_log("Expected data greater than buffer size\n");
+			talloc_free(ifconf);
+			return;
+		}
+
+		/* IP address */
+		ipstr = talloc_array(ifconf, char, addr_len);
+		if (!inet_ntop(addr_type, &buf[i], ipstr, addr_len)) {
+			pb_log("Failed to convert ipaddr: %m\n");
+			talloc_free(ifconf);
+			return;
+		}
+		i += ipsize;
+
+		/* IP address subnet */
+		ifconf->static_config.address = talloc_asprintf(ifconf,
+						"%s/%u", ipstr, buf[i]);
+		i++;
+
+		/* Gateway address */
+		gatewaystr = talloc_array(ifconf, char, addr_len);
+		if (!inet_ntop(addr_type, &buf[i], gatewaystr, addr_len)) {
+			pb_log("Failed to convert gateway: %m\n");
+			talloc_free(ifconf);
+			return;
+		}
+		ifconf->static_config.gateway = gatewaystr;
+		i += ipsize;
+	}
+
+	pb_log("Applying IPMI network config\n");
+
+	/* Replace any existing interface config */
+	talloc_free(config->network.interfaces);
+	config->network.n_interfaces = 1;
+	config->network.interfaces = talloc(config, struct interface_config *);
+	config->network.interfaces[0] = ifconf;
+}
diff --git a/discover/ipmi.h b/discover/ipmi.h
index 611cd49..85c91f4 100644
--- a/discover/ipmi.h
+++ b/discover/ipmi.h
@@ -38,4 +38,8 @@ int ipmi_transaction(struct ipmi *ipmi, uint8_t netfn, uint8_t cmd,
 		uint8_t *resp_buf, uint16_t *resp_len,
 		int timeout_ms);
 
+void parse_ipmi_interface_override(struct config *config, uint8_t *buf,
+				uint16_t len);
+
+
 #endif /* _IPMI_H */
diff --git a/discover/platform-powerpc.c b/discover/platform-powerpc.c
index 78b76d3..98deea5 100644
--- a/discover/platform-powerpc.c
+++ b/discover/platform-powerpc.c
@@ -8,6 +8,7 @@
 #include <sys/wait.h>
 #include <sys/fcntl.h>
 #include <sys/stat.h>
+#include <asm/byteorder.h>
 
 #include <file/file.h>
 #include <talloc/talloc.h>
@@ -1113,6 +1114,97 @@ static void get_ipmi_bmc_versions(struct platform *p, struct system_info *info)
 		pb_log("Failed to retrieve Golden Device ID from IPMI\n");
 }
 
+static void get_ipmi_network_override(struct platform_powerpc *platform,
+			struct config *config)
+{
+	uint16_t min_len = 12, resp_len = 53, version;
+	const uint32_t magic_value = 0x21706221;
+	uint8_t resp[resp_len];
+	uint32_t cookie;
+	int i, rc;
+	uint8_t req[] = {
+		0x61, /* parameter selector: OEM section (network) */
+		0x00, /* no set selector */
+		0x00, /* no block selector */
+	};
+
+	rc = ipmi_transaction(platform->ipmi, IPMI_NETFN_CHASSIS,
+			IPMI_CMD_CHASSIS_GET_SYSTEM_BOOT_OPTIONS,
+			req, sizeof(req),
+			resp, &resp_len,
+			ipmi_timeout);
+
+	pb_debug("IPMI net override resp [%d][%d]:\n", rc, resp_len);
+	if (resp_len > 0) {
+		for (i = 0; i < resp_len; i++) {
+		        pb_debug(" %02x", resp[i]);
+			if (i && (i + 1) % 16 == 0 && i != resp_len - 1)
+				pb_debug("\n");
+			else if (i && (i + 1) % 8 == 0)
+				pb_debug(" ");
+		}
+		pb_debug("\n");
+	}
+
+	if (rc) {
+		pb_debug("IPMI network config option unavailable\n");
+		return;
+	}
+
+	if (resp_len < min_len) {
+		pb_debug("IPMI net response too small\n");
+		return;
+	}
+
+	if (resp[0] != 0) {
+		pb_log("platform: non-zero completion code %d from IPMI network req\n",
+		       resp[0]);
+		return;
+	}
+
+	/* Check for correct parameter version */
+	if ((resp[1] & 0xf) != 0x1) {
+		pb_log("platform: unexpected version (0x%x) in network override response\n",
+		       resp[0]);
+		return;
+	}
+
+	/* Check for valid parameters. For now ignore the persistent flag */
+	if (resp[2] & 0x80) {
+		pb_debug("platform: network override is invalid/locked\n");
+		return;
+	}
+
+	/* Check for valid parameters in the boot flags section, ignoring the
+	 * persistent bit */
+	if (!(resp[3] & 0x80)) {
+		pb_debug("platform: network override valid flag not set\n");
+		return;
+	}
+
+	/* Check 4-byte cookie value */
+	i = 4;
+	memcpy(&cookie, &resp[i], sizeof(cookie));
+	cookie = __be32_to_cpu(cookie);
+	if (cookie != magic_value) {
+		pb_log("%s: Incorrect cookie %x\n", __func__, cookie);
+		return;
+	}
+	i += sizeof(cookie);
+
+	/* Check 2-byte version number */
+	memcpy(&version, &resp[i], sizeof(version));
+	version = __be16_to_cpu(version);
+	i += sizeof(version);
+	if (version != 1) {
+		pb_debug("Unexpected version: %u\n", version);
+		return;
+	}
+
+	/* Interpret the rest of the interface config */
+	parse_ipmi_interface_override(config, &resp[i], resp_len - i);
+}
+
 static int load_config(struct platform *p, struct config *config)
 {
 	struct platform_powerpc *platform = to_platform_powerpc(p);
@@ -1134,6 +1226,9 @@ static int load_config(struct platform *p, struct config *config)
 		}
 	}
 
+	if (platform->ipmi)
+		get_ipmi_network_override(platform, config);
+
 	return 0;
 }