Add netdump support to dumpon(8).

A new usage is added so that parameters for netdump may be specified.
Specifically, one configures an interface for netdump with:

# dumpon -c <client IP> -s <server IP> [-g <gateway IP>] <iface name>

Reviewed by:	bdrewery, cem (earlier versions), sbruno
MFC after:	1 month
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D15254

2 files changed, 328 insertions, 100 deletions

diff --git a/sbin/dumpon/dumpon.8 b/sbin/dumpon/dumpon.8
index e6aace1bbbc0..776c67f7b2d5 100644
--- a/sbin/dumpon/dumpon.8
+++ b/sbin/dumpon/dumpon.8
@@ -28,7 +28,7 @@
 .\"     From: @(#)swapon.8	8.1 (Berkeley) 6/5/93
 .\" $FreeBSD$
 .\"
-.Dd February 13, 2018
+.Dd March 6, 2018
 .Dt DUMPON 8
 .Os
 .Sh NAME
@@ -37,10 +37,19 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl v
-.Op Fl k Ar public_key_file
+.Op Fl k Ar pubkey
+.Op Fl Z
 .Op Fl z
+.Ar device
+.Nm
+.Op Fl v
+.Op Fl k Ar pubkey
 .Op Fl Z
-.Ar special_file
+.Op Fl z
+.Op Fl g Ar gateway | Li default
+.Fl s Ar server
+.Fl c Ar client
+.Ar iface
 .Nm
 .Op Fl v
 .Cm off
@@ -60,7 +69,7 @@ normally occur from the system multi-user initialization file
 controlled by the
 .Dq dumpdev
 and
-.Dq dumppubkey
+.Dq dumpon_flags
 variables in the boot time configuration file
 .Pa /etc/rc.conf .
 .Pp
@@ -72,8 +81,7 @@ Alternatively, full memory dumps can be enabled by setting the
 variable to 0.
 .Pp
 For systems using full memory dumps, the size of the specified dump
-device must be at
-least the size of physical memory.
+device must be at least the size of physical memory.
 Even though an additional 64 kB header is added to the dump, the BIOS for a
 platform typically holds back some memory, so it is not usually
 necessary to size the dump device larger than the actual amount of RAM
@@ -86,8 +94,37 @@ total amount of physical memory as reported by the
 .Xr sysctl 8
 variable.
 .Pp
+.Nm
+is used to configure a local storage device as the dump device.
+With additional parameters, the kernel can instead be configured to
+transmit a dump to a remote server using
+.Xr netdump 4 .
+This eliminates the need to reserve space for saving crash dumps and
+is especially useful in diskless environments.
+The
+.Xr netdump 4
+server address is specified with
+.Fl s Ar server ,
+and the local address is specified with
+.Fl c Ar client .
+The
+.Fl g Ar gateway
+parameter may be used to specify a first-hop router to the server,
+or to specify that the currently configured default gateway is to
+be used.
+Note that the
+.Xr netdump 4
+configuration is not automatically updated if any network configuration
+(e.g., the default route) changes after the
+.Nm
+invocation.
+The name of the interface to be used must be specified as
+.Ar iface .
+The interface must be up in order to configure
+.Xr netdump 4 .
+.Pp
 The
-.Op Fl k Ar public_key_file
+.Fl k Ar pubkey
 flag causes
 .Nm
 to generate a one-time key for kernel crash dump encryption.
@@ -95,16 +132,16 @@ The key will be replaced by a new one when the
 .Nm
 utility is run again.
 The key is encrypted using
-.Ar public_key_file .
+.Ar pubkey .
 This process is sandboxed using
 .Xr capsicum 4 .
 Both plain and encrypted keys are sent to the kernel using
 .Dv DIOCSKERNELDUMP
 .Xr ioctl 2 .
 A user can specify the
-.Ar public_key_file
+.Ar pubkey
 in the
-.Dq dumppubkey
+.Dq dumpon_flags
 variable defined in
 .Pa /etc/rc.conf
 for use with the
@@ -172,13 +209,13 @@ should be used as the dump device.
 The
 .Nm
 utility operates by opening
-.Ar special_file
+.Ar device
 and making a
 .Dv DIOCSKERNELDUMP
 .Xr ioctl 2
 request on it to save kernel crash dumps.
 If
-.Ar special_file
+.Ar device
 is the text string:
 .Dq Li off ,
 .Nm
diff --git a/sbin/dumpon/dumpon.c b/sbin/dumpon/dumpon.c
index 0ae95e6e1847..ddd8d4921696 100644
--- a/sbin/dumpon/dumpon.c
+++ b/sbin/dumpon/dumpon.c
@@ -46,12 +46,15 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/capsicum.h>
 #include <sys/disk.h>
+#include <sys/socket.h>
 #include <sys/sysctl.h>
 
 #include <assert.h>
 #include <err.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <ifaddrs.h>
+#include <netdb.h>
 #include <paths.h>
 #include <stdbool.h>
 #include <stdint.h>
@@ -61,6 +64,15 @@ __FBSDID("$FreeBSD$");
 #include <sysexits.h>
 #include <unistd.h>
 
+#include <arpa/inet.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/route.h>
+
+#include <netinet/in.h>
+#include <netinet/netdump/netdump.h>
+
 #ifdef HAVE_CRYPTO
 #include <openssl/err.h>
 #include <openssl/pem.h>
@@ -69,16 +81,109 @@ __FBSDID("$FreeBSD$");
 
 static int	verbose;
 
-static void
+static void _Noreturn
 usage(void)
 {
-	fprintf(stderr, "%s\n%s\n%s\n",
-	    "usage: dumpon [-v] [-k public_key_file] [-Zz] special_file",
-	    "       dumpon [-v] off",
-	    "       dumpon [-v] -l");
+	fprintf(stderr,
+    "usage: dumpon [-v] [-k <pubkey>] [-Zz] <device>\n"
+    "       dumpon [-v] [-k <pubkey>] [-Zz]\n"
+    "              [-g <gateway>|default] -s <server> -c <client> <iface>\n"
+    "       dumpon [-v] off\n"
+    "       dumpon [-v] -l\n");
 	exit(EX_USAGE);
 }
 
+/*
+ * Look for a default route on the specified interface.
+ */
+static char *
+find_gateway(const char *ifname)
+{
+	struct ifaddrs *ifa, *ifap;
+	struct rt_msghdr *rtm;
+	struct sockaddr *sa;
+	struct sockaddr_dl *sdl;
+	struct sockaddr_in *dst, *mask, *gw;
+	char *buf, *next, *ret;
+	size_t sz;
+	int error, i, ifindex, mib[7];
+
+	ret = NULL;
+
+	/* First look up the interface index. */
+	if (getifaddrs(&ifap) != 0)
+		err(EX_OSERR, "getifaddrs");
+	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
+		if (ifa->ifa_addr->sa_family != AF_LINK)
+			continue;
+		if (strcmp(ifa->ifa_name, ifname) == 0) {
+			sdl = (struct sockaddr_dl *)(void *)ifa->ifa_addr;
+			ifindex = sdl->sdl_index;
+			break;
+		}
+	}
+	if (ifa == NULL)
+		errx(1, "couldn't find interface index for '%s'", ifname);
+	freeifaddrs(ifap);
+
+	/* Now get the IPv4 routing table. */
+	mib[0] = CTL_NET;
+	mib[1] = PF_ROUTE;
+	mib[2] = 0;
+	mib[3] = AF_INET;
+	mib[4] = NET_RT_DUMP;
+	mib[5] = 0;
+	mib[6] = -1; /* FIB */
+
+	for (;;) {
+		if (sysctl(mib, nitems(mib), NULL, &sz, NULL, 0) != 0)
+			err(EX_OSERR, "sysctl(NET_RT_DUMP)");
+		buf = malloc(sz);
+		error = sysctl(mib, nitems(mib), buf, &sz, NULL, 0);
+		if (error == 0)
+			break;
+		if (errno != ENOMEM)
+			err(EX_OSERR, "sysctl(NET_RT_DUMP)");
+		free(buf);
+	}
+
+	for (next = buf; next < buf + sz; next += rtm->rtm_msglen) {
+		rtm = (struct rt_msghdr *)(void *)next;
+		if (rtm->rtm_version != RTM_VERSION)
+			continue;
+		if ((rtm->rtm_flags & RTF_GATEWAY) == 0 ||
+		    rtm->rtm_index != ifindex)
+			continue;
+
+		dst = gw = mask = NULL;
+		sa = (struct sockaddr *)(rtm + 1);
+		for (i = 0; i < RTAX_MAX; i++) {
+			if ((rtm->rtm_addrs & (1 << i)) != 0) {
+				switch (i) {
+				case RTAX_DST:
+					dst = (void *)sa;
+					break;
+				case RTAX_GATEWAY:
+					gw = (void *)sa;
+					break;
+				case RTAX_NETMASK:
+					mask = (void *)sa;
+					break;
+				}
+			}
+			sa = (struct sockaddr *)((char *)sa + SA_SIZE(sa));
+		}
+
+		if (dst->sin_addr.s_addr == INADDR_ANY &&
+		    mask->sin_addr.s_addr == 0) {
+			ret = inet_ntoa(gw->sin_addr);
+			break;
+		}
+	}
+	free(buf);
+	return (ret);
+}
+
 static void
 check_size(int fd, const char *fn)
 {
@@ -107,13 +212,13 @@ check_size(int fd, const char *fn)
 
 #ifdef HAVE_CRYPTO
 static void
-genkey(const char *pubkeyfile, struct diocskerneldump_arg *kda)
+genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
 {
 	FILE *fp;
 	RSA *pubkey;
 
 	assert(pubkeyfile != NULL);
-	assert(kda != NULL);
+	assert(kdap != NULL);
 
 	fp = NULL;
 	pubkey = NULL;
@@ -137,21 +242,21 @@ genkey(const char *pubkeyfile, struct diocskerneldump_arg *kda)
 	if (pubkey == NULL)
 		errx(1, "Unable to read data from %s.", pubkeyfile);
 
-	kda->kda_encryptedkeysize = RSA_size(pubkey);
-	if (kda->kda_encryptedkeysize > KERNELDUMP_ENCKEY_MAX_SIZE) {
+	kdap->kda_encryptedkeysize = RSA_size(pubkey);
+	if (kdap->kda_encryptedkeysize > KERNELDUMP_ENCKEY_MAX_SIZE) {
 		errx(1, "Public key has to be at most %db long.",
 		    8 * KERNELDUMP_ENCKEY_MAX_SIZE);
 	}
 
-	kda->kda_encryptedkey = calloc(1, kda->kda_encryptedkeysize);
-	if (kda->kda_encryptedkey == NULL)
+	kdap->kda_encryptedkey = calloc(1, kdap->kda_encryptedkeysize);
+	if (kdap->kda_encryptedkey == NULL)
 		err(1, "Unable to allocate encrypted key");
 
-	kda->kda_encryption = KERNELDUMP_ENC_AES_256_CBC;
-	arc4random_buf(kda->kda_key, sizeof(kda->kda_key));
-	if (RSA_public_encrypt(sizeof(kda->kda_key), kda->kda_key,
-	    kda->kda_encryptedkey, pubkey,
-	    RSA_PKCS1_PADDING) != (int)kda->kda_encryptedkeysize) {
+	kdap->kda_encryption = KERNELDUMP_ENC_AES_256_CBC;
+	arc4random_buf(kdap->kda_key, sizeof(kdap->kda_key));
+	if (RSA_public_encrypt(sizeof(kdap->kda_key), kdap->kda_key,
+	    kdap->kda_encryptedkey, pubkey,
+	    RSA_PKCS1_PADDING) != (int)kdap->kda_encryptedkeysize) {
 		errx(1, "Unable to encrypt the one-time key.");
 	}
 	RSA_free(pubkey);
@@ -162,8 +267,10 @@ static void
 listdumpdev(void)
 {
 	char dumpdev[PATH_MAX];
+	struct netdump_conf ndconf;
 	size_t len;
 	const char *sysctlname = "kern.shutdown.dumpdevname";
+	int fd;
 
 	len = sizeof(dumpdev);
 	if (sysctlbyname(sysctlname, &dumpdev, &len, NULL, 0) != 0) {
@@ -174,36 +281,88 @@ listdumpdev(void)
 			err(EX_OSERR, "Sysctl get '%s'\n", sysctlname);
 		}
 	}
-	if (verbose) {
+	if (strlen(dumpdev) == 0)
+		(void)strlcpy(dumpdev, _PATH_DEVNULL, sizeof(dumpdev));
+
+	if (verbose)
 		printf("kernel dumps on ");
+	printf("%s\n", dumpdev);
+
+	/* If netdump is enabled, print the configuration parameters. */
+	if (verbose) {
+		fd = open(_PATH_NETDUMP, O_RDONLY);
+		if (fd < 0) {
+			if (errno != ENOENT)
+				err(EX_OSERR, "opening %s", _PATH_NETDUMP);
+			return;
+		}
+		if (ioctl(fd, NETDUMPGCONF, &ndconf) != 0) {
+			if (errno != ENXIO)
+				err(EX_OSERR, "ioctl(NETDUMPGCONF)");
+			(void)close(fd);
+			return;
+		}
+
+		printf("server address: %s\n", inet_ntoa(ndconf.ndc_server));
+		printf("client address: %s\n", inet_ntoa(ndconf.ndc_client));
+		printf("gateway address: %s\n", inet_ntoa(ndconf.ndc_gateway));
+		(void)close(fd);
 	}
-	if (strlen(dumpdev) == 0) {
-		printf("%s\n", _PATH_DEVNULL);
-	} else {
-		printf("%s\n", dumpdev);
+}
+
+static int
+opendumpdev(const char *arg, char *dumpdev)
+{
+	int fd, i;
+
+	if (strncmp(arg, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
+		strlcpy(dumpdev, arg, PATH_MAX);
+	else {
+		i = snprintf(dumpdev, PATH_MAX, "%s%s", _PATH_DEV, arg);
+		if (i < 0)
+			err(EX_OSERR, "%s", arg);
+		if (i >= PATH_MAX)
+			errc(EX_DATAERR, EINVAL, "%s", arg);
 	}
+
+	fd = open(dumpdev, O_RDONLY);
+	if (fd < 0)
+		err(EX_OSFILE, "%s", dumpdev);
+	return (fd);
 }
 
 int
 main(int argc, char *argv[])
 {
-	struct diocskerneldump_arg kda;
-	const char *pubkeyfile;
-	int ch;
-	int i, fd;
-	int do_listdumpdev = 0;
-	bool enable, gzip, zstd;
-
-	gzip = zstd = false;
+	char dumpdev[PATH_MAX];
+	struct diocskerneldump_arg _kda, *kdap;
+	struct netdump_conf ndconf;
+	struct addrinfo hints, *res;
+	const char *dev, *pubkeyfile, *server, *client, *gateway;
+	int ch, error, fd;
+	bool enable, gzip, list, netdump, zstd;
+
+	gzip = list = netdump = zstd = false;
+	kdap = NULL;
 	pubkeyfile = NULL;
+	server = client = gateway = NULL;
 
-	while ((ch = getopt(argc, argv, "k:lvZz")) != -1)
-		switch((char)ch) {
+	while ((ch = getopt(argc, argv, "c:g:k:ls:vZz")) != -1)
+		switch ((char)ch) {
+		case 'c':
+			client = optarg;
+			break;
+		case 'g':
+			gateway = optarg;
+			break;
 		case 'k':
 			pubkeyfile = optarg;
 			break;
 		case 'l':
-			do_listdumpdev = 1;
+			list = true;
+			break;
+		case 's':
+			server = optarg;
 			break;
 		case 'v':
 			verbose = 1;
@@ -224,7 +383,7 @@ main(int argc, char *argv[])
 	argc -= optind;
 	argv += optind;
 
-	if (do_listdumpdev) {
+	if (list) {
 		listdumpdev();
 		exit(EX_OK);
 	}
@@ -232,72 +391,104 @@ main(int argc, char *argv[])
 	if (argc != 1)
 		usage();
 
-	enable = (strcmp(argv[0], "off") != 0);
 #ifndef HAVE_CRYPTO
-	if (pubkeyfile != NULL) {
-		enable = false;
-		warnx("Unable to use the public key. Recompile dumpon with OpenSSL support.");
-	}
+	if (pubkeyfile != NULL)
+		errx("Unable to use the public key. Recompile dumpon with OpenSSL support.");
 #endif
 
-	if (enable) {
-		char tmp[PATH_MAX];
-		char *dumpdev;
+	if (server != NULL && client != NULL) {
+		enable = true;
+		dev = _PATH_NETDUMP;
+		netdump = true;
+		kdap = &ndconf.ndc_kda;
+	} else if (server == NULL && client == NULL && argc > 0) {
+		enable = strcmp(argv[0], "off") != 0;
+		dev = enable ? argv[0] : _PATH_DEVNULL;
+		netdump = false;
+		kdap = &_kda;
+	} else
+		usage();
 
-		if (strncmp(argv[0], _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) {
-			dumpdev = argv[0];
-		} else {
-			i = snprintf(tmp, PATH_MAX, "%s%s", _PATH_DEV, argv[0]);
-			if (i < 0) {
-				err(EX_OSERR, "%s", argv[0]);
-			} else if (i >= PATH_MAX) {
-				errno = EINVAL;
-				err(EX_DATAERR, "%s", argv[0]);
-			}
-			dumpdev = tmp;
-		}
-		fd = open(dumpdev, O_RDONLY);
-		if (fd < 0)
-			err(EX_OSFILE, "%s", dumpdev);
+	fd = opendumpdev(dev, dumpdev);
+	if (!netdump && !gzip)
+		check_size(fd, dumpdev);
 
-		if (!gzip && !zstd)
-			check_size(fd, dumpdev);
+	bzero(kdap, sizeof(*kdap));
+	kdap->kda_enable = 0;
+	if (ioctl(fd, DIOCSKERNELDUMP, kdap) != 0)
+		err(EX_OSERR, "ioctl(DIOCSKERNELDUMP)");
+	if (!enable)
+		exit(EX_OK);
 
-		bzero(&kda, sizeof(kda));
-		kda.kda_enable = 0;
-		i = ioctl(fd, DIOCSKERNELDUMP, &kda);
-		explicit_bzero(&kda, sizeof(kda));
+	explicit_bzero(kdap, sizeof(*kdap));
+	kdap->kda_enable = 1;
+	kdap->kda_compression = KERNELDUMP_COMP_NONE;
+	if (zstd)
+		kdap->kda_compression = KERNELDUMP_COMP_ZSTD;
+	else if (gzip)
+		kdap->kda_compression = KERNELDUMP_COMP_GZIP;
+
+	if (netdump) {
+		memset(&hints, 0, sizeof(hints));
+		hints.ai_family = AF_INET;
+		hints.ai_protocol = IPPROTO_UDP;
+		res = NULL;
+		error = getaddrinfo(server, NULL, &hints, &res);
+		if (error != 0)
+			err(1, "%s", gai_strerror(error));
+		if (res == NULL)
+			errx(1, "failed to resolve '%s'", server);
+		server = inet_ntoa(
+		    ((struct sockaddr_in *)(void *)res->ai_addr)->sin_addr);
+		freeaddrinfo(res);
+
+		if (strlcpy(ndconf.ndc_iface, argv[0],
+		    sizeof(ndconf.ndc_iface)) >= sizeof(ndconf.ndc_iface))
+			errx(EX_USAGE, "invalid interface name '%s'", argv[0]);
+		if (inet_aton(server, &ndconf.ndc_server) == 0)
+			errx(EX_USAGE, "invalid server address '%s'", server);
+		if (inet_aton(client, &ndconf.ndc_client) == 0)
+			errx(EX_USAGE, "invalid client address '%s'", client);
+
+		if (gateway == NULL)
+			gateway = server;
+		else if (strcmp(gateway, "default") == 0 &&
+		    (gateway = find_gateway(argv[0])) == NULL)
+			errx(EX_NOHOST,
+			    "failed to look up next-hop router for %s", server);
+		if (inet_aton(gateway, &ndconf.ndc_gateway) == 0)
+			errx(EX_USAGE, "invalid gateway address '%s'", gateway);
 
 #ifdef HAVE_CRYPTO
 		if (pubkeyfile != NULL)
-			genkey(pubkeyfile, &kda);
+			genkey(pubkeyfile, kdap);
 #endif
-
-		kda.kda_enable = 1;
-		kda.kda_compression = KERNELDUMP_COMP_NONE;
-		if (zstd)
-			kda.kda_compression = KERNELDUMP_COMP_ZSTD;
-		else if (gzip)
-			kda.kda_compression = KERNELDUMP_COMP_GZIP;
-		i = ioctl(fd, DIOCSKERNELDUMP, &kda);
-		explicit_bzero(kda.kda_encryptedkey, kda.kda_encryptedkeysize);
-		free(kda.kda_encryptedkey);
-		explicit_bzero(&kda, sizeof(kda));
-		if (i == 0 && verbose)
-			printf("kernel dumps on %s\n", dumpdev);
+		error = ioctl(fd, NETDUMPSCONF, &ndconf);
+		if (error != 0)
+			error = errno;
+		explicit_bzero(kdap->kda_encryptedkey,
+		    kdap->kda_encryptedkeysize);
+		free(kdap->kda_encryptedkey);
+		explicit_bzero(kdap, sizeof(*kdap));
+		if (error != 0)
+			errc(EX_OSERR, error, "ioctl(NETDUMPSCONF)");
 	} else {
-		fd = open(_PATH_DEVNULL, O_RDONLY);
-		if (fd < 0)
-			err(EX_OSFILE, "%s", _PATH_DEVNULL);
-
-		kda.kda_enable = 0;
-		i = ioctl(fd, DIOCSKERNELDUMP, &kda);
-		explicit_bzero(&kda, sizeof(kda));
-		if (i == 0 && verbose)
-			printf("kernel dumps disabled\n");
+#ifdef HAVE_CRYPTO
+		if (pubkeyfile != NULL)
+			genkey(pubkeyfile, kdap);
+#endif
+		error = ioctl(fd, DIOCSKERNELDUMP, kdap);
+		if (error != 0)
+			error = errno;
+		explicit_bzero(kdap->kda_encryptedkey,
+		    kdap->kda_encryptedkeysize);
+		free(kdap->kda_encryptedkey);
+		explicit_bzero(kdap, sizeof(*kdap));
+		if (error != 0)
+			errc(EX_OSERR, error, "ioctl(DIOCSKERNELDUMP)");
 	}
-	if (i < 0)
-		err(EX_OSERR, "ioctl(DIOCSKERNELDUMP)");
+	if (verbose)
+		printf("kernel dumps on %s\n", dumpdev);
 
-	exit (0);
+	exit(EX_OK);
 }