freebsd-dev/sbin/dumpon/dumpon.c
Mitchell Horne 6543fa5a5c dumpon: warn if the configured netdump link is down
Previously we expected the DIOCSKERNELDUMP ioctl to return ENXIO if the
interface was down, but it does not actually do this. Grab the link
status using getifaddrs(3) instead, and downgrade this case from an
error to a warning; the user might bring the link back up at a later
time.

Reviewed by:	cem
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D35196
2022-05-14 10:27:54 -03:00

707 lines
18 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1980, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if 0
#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1980, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "From: @(#)swapon.c 8.1 (Berkeley) 6/5/93";
#endif /* not lint */
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/disk.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/wait.h>
#include <assert.h>
#include <capsicum_helpers.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>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#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>
#include <openssl/rand.h>
#include <openssl/rsa.h>
#endif
static int verbose;
static void _Noreturn
usage(void)
{
fprintf(stderr,
"usage: dumpon [-i index] [-r] [-v] [-k <pubkey>] [-Zz] <device>\n"
" dumpon [-i index] [-r] [-v] [-k <pubkey>] [-Zz]\n"
" [-g <gateway>] -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];
/* 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);
}
ret = NULL;
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_link_status(const char *ifname)
{
struct ifaddrs *ifap, *ifa;
if (getifaddrs(&ifap) != 0)
err(EX_OSERR, "getifaddrs");
for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
if (strcmp(ifname, ifa->ifa_name) != 0)
continue;
if ((ifa->ifa_flags & IFF_UP) == 0) {
warnx("warning: %s's link is down", ifname);
}
break;
}
freeifaddrs(ifap);
}
static void
check_size(int fd, const char *fn)
{
int name[] = { CTL_HW, HW_PHYSMEM };
size_t namelen = nitems(name);
unsigned long physmem;
size_t len;
off_t mediasize;
int minidump;
len = sizeof(minidump);
if (sysctlbyname("debug.minidump", &minidump, &len, NULL, 0) == 0 &&
minidump == 1)
return;
len = sizeof(physmem);
if (sysctl(name, namelen, &physmem, &len, NULL, 0) != 0)
err(EX_OSERR, "can't get memory size");
if (ioctl(fd, DIOCGMEDIASIZE, &mediasize) != 0)
err(EX_OSERR, "%s: can't get size", fn);
if ((uintmax_t)mediasize < (uintmax_t)physmem)
errx(EX_IOERR, "%s is smaller than physical memory", fn);
}
#ifdef HAVE_CRYPTO
static void
_genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
{
FILE *fp;
RSA *pubkey;
assert(pubkeyfile != NULL);
assert(kdap != NULL);
fp = NULL;
pubkey = NULL;
fp = fopen(pubkeyfile, "r");
if (fp == NULL)
err(1, "Unable to open %s", pubkeyfile);
/*
* Obsolescent OpenSSL only knows about /dev/random, and needs to
* pre-seed before entering cap mode. For whatever reason,
* RSA_pub_encrypt uses the internal PRNG.
*/
#if OPENSSL_VERSION_NUMBER < 0x10100000L
{
unsigned char c[1];
RAND_bytes(c, 1);
}
#endif
if (caph_enter() < 0)
err(1, "Unable to enter capability mode");
pubkey = RSA_new();
if (pubkey == NULL) {
errx(1, "Unable to allocate an RSA structure: %s",
ERR_error_string(ERR_get_error(), NULL));
}
pubkey = PEM_read_RSA_PUBKEY(fp, &pubkey, NULL, NULL);
fclose(fp);
fp = NULL;
if (pubkey == NULL)
errx(1, "Unable to read data from %s.", pubkeyfile);
/*
* RSA keys under ~1024 bits are trivially factorable (2018). OpenSSL
* provides an API for RSA keys to estimate the symmetric-cipher
* "equivalent" bits of security (defined in NIST SP800-57), which as
* of this writing equates a 2048-bit RSA key to 112 symmetric cipher
* bits.
*
* Use this API as a seatbelt to avoid suggesting to users that their
* privacy is protected by encryption when the key size is insufficient
* to prevent compromise via factoring.
*
* Future work: Sanity check for weak 'e', and sanity check for absence
* of 'd' (i.e., the supplied key is a public key rather than a full
* keypair).
*/
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
if (RSA_security_bits(pubkey) < 112)
#else
if (RSA_size(pubkey) * 8 < 2048)
#endif
errx(1, "Small RSA keys (you provided: %db) can be "
"factored cheaply. Please generate a larger key.",
RSA_size(pubkey) * 8);
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);
}
kdap->kda_encryptedkey = calloc(1, kdap->kda_encryptedkeysize);
if (kdap->kda_encryptedkey == NULL)
err(1, "Unable to allocate encrypted key");
/*
* If no cipher was specified, choose a reasonable default.
*/
if (kdap->kda_encryption == KERNELDUMP_ENC_NONE)
kdap->kda_encryption = KERNELDUMP_ENC_CHACHA20;
else if (kdap->kda_encryption == KERNELDUMP_ENC_AES_256_CBC &&
kdap->kda_compression != KERNELDUMP_COMP_NONE)
errx(EX_USAGE, "Unpadded AES256-CBC mode cannot be used "
"with compression.");
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_OAEP_PADDING) != (int)kdap->kda_encryptedkeysize) {
errx(1, "Unable to encrypt the one-time key: %s",
ERR_error_string(ERR_get_error(), NULL));
}
RSA_free(pubkey);
}
/*
* Run genkey() in a child so it can use capability mode without affecting
* the rest of the runtime.
*/
static void
genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
{
pid_t pid;
int error, filedes[2], status;
ssize_t bytes;
if (pipe2(filedes, O_CLOEXEC) != 0)
err(1, "pipe");
pid = fork();
switch (pid) {
case -1:
err(1, "fork");
break;
case 0:
close(filedes[0]);
_genkey(pubkeyfile, kdap);
/* Write the new kdap back to the parent. */
bytes = write(filedes[1], kdap, sizeof(*kdap));
if (bytes != sizeof(*kdap))
err(1, "genkey pipe write");
bytes = write(filedes[1], kdap->kda_encryptedkey,
kdap->kda_encryptedkeysize);
if (bytes != (ssize_t)kdap->kda_encryptedkeysize)
err(1, "genkey pipe write kda_encryptedkey");
_exit(0);
}
close(filedes[1]);
/* Read in the child's genkey() result into kdap. */
bytes = read(filedes[0], kdap, sizeof(*kdap));
if (bytes != sizeof(*kdap))
errx(1, "genkey pipe read");
if (kdap->kda_encryptedkeysize > KERNELDUMP_ENCKEY_MAX_SIZE)
errx(1, "Public key has to be at most %db long.",
8 * KERNELDUMP_ENCKEY_MAX_SIZE);
kdap->kda_encryptedkey = calloc(1, kdap->kda_encryptedkeysize);
if (kdap->kda_encryptedkey == NULL)
err(1, "Unable to allocate encrypted key");
bytes = read(filedes[0], kdap->kda_encryptedkey,
kdap->kda_encryptedkeysize);
if (bytes != (ssize_t)kdap->kda_encryptedkeysize)
errx(1, "genkey pipe read kda_encryptedkey");
error = waitpid(pid, &status, WEXITED);
if (error == -1)
err(1, "waitpid");
if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
errx(1, "genkey child exited with status %d",
WEXITSTATUS(status));
else if (WIFSIGNALED(status))
errx(1, "genkey child exited with signal %d",
WTERMSIG(status));
close(filedes[0]);
}
#endif
static void
listdumpdev(void)
{
static char ip[200];
char dumpdev[PATH_MAX];
struct diocskerneldump_arg ndconf;
size_t len;
const char *sysctlname = "kern.shutdown.dumpdevname";
int fd;
len = sizeof(dumpdev);
if (sysctlbyname(sysctlname, &dumpdev, &len, NULL, 0) != 0) {
if (errno == ENOMEM) {
err(EX_OSERR, "Kernel returned too large of a buffer for '%s'\n",
sysctlname);
} else {
err(EX_OSERR, "Sysctl get '%s'\n", sysctlname);
}
}
if (strlen(dumpdev) == 0)
(void)strlcpy(dumpdev, _PATH_DEVNULL, sizeof(dumpdev));
if (verbose) {
char *ctx, *dd;
unsigned idx;
printf("kernel dumps on priority: device\n");
idx = 0;
ctx = dumpdev;
while ((dd = strsep(&ctx, ",")) != NULL)
printf("%u: %s\n", idx++, dd);
} else
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, DIOCGKERNELDUMP, &ndconf) != 0) {
if (errno != ENXIO)
err(EX_OSERR, "ioctl(DIOCGKERNELDUMP)");
(void)close(fd);
return;
}
printf("server address: %s\n",
inet_ntop(ndconf.kda_af, &ndconf.kda_server, ip,
sizeof(ip)));
printf("client address: %s\n",
inet_ntop(ndconf.kda_af, &ndconf.kda_client, ip,
sizeof(ip)));
printf("gateway address: %s\n",
inet_ntop(ndconf.kda_af, &ndconf.kda_gateway, ip,
sizeof(ip)));
(void)close(fd);
}
}
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[])
{
char dumpdev[PATH_MAX];
struct diocskerneldump_arg ndconf, *kdap;
struct addrinfo hints, *res;
const char *dev, *pubkeyfile, *server, *client, *gateway;
int ch, error, fd, cipher;
bool gzip, list, netdump, zstd, insert, rflag;
uint8_t ins_idx;
gzip = list = netdump = zstd = insert = rflag = false;
kdap = NULL;
pubkeyfile = NULL;
server = client = gateway = NULL;
ins_idx = KDA_APPEND;
cipher = KERNELDUMP_ENC_NONE;
while ((ch = getopt(argc, argv, "C:c:g:i:k:lrs:vZz")) != -1)
switch ((char)ch) {
case 'C':
if (strcasecmp(optarg, "chacha") == 0 ||
strcasecmp(optarg, "chacha20") == 0)
cipher = KERNELDUMP_ENC_CHACHA20;
else if (strcasecmp(optarg, "aes-cbc") == 0 ||
strcasecmp(optarg, "aes256-cbc") == 0)
cipher = KERNELDUMP_ENC_AES_256_CBC;
else
errx(EX_USAGE, "Unrecognized cipher algorithm "
"'%s'", optarg);
break;
case 'c':
client = optarg;
break;
case 'g':
gateway = optarg;
break;
case 'i':
{
int i;
i = atoi(optarg);
if (i < 0 || i >= KDA_APPEND - 1)
errx(EX_USAGE,
"-i index must be between zero and %d.",
(int)KDA_APPEND - 2);
insert = true;
ins_idx = i;
}
break;
case 'k':
pubkeyfile = optarg;
break;
case 'l':
list = true;
break;
case 'r':
rflag = true;
break;
case 's':
server = optarg;
break;
case 'v':
verbose = 1;
break;
case 'Z':
zstd = true;
break;
case 'z':
gzip = true;
break;
default:
usage();
}
if (gzip && zstd)
errx(EX_USAGE, "The -z and -Z options are mutually exclusive.");
if (insert && rflag)
errx(EX_USAGE, "The -i and -r options are mutually exclusive.");
argc -= optind;
argv += optind;
if (list) {
listdumpdev();
exit(EX_OK);
}
if (argc != 1)
usage();
#ifdef HAVE_CRYPTO
if (cipher != KERNELDUMP_ENC_NONE && pubkeyfile == NULL) {
errx(EX_USAGE, "-C option requires a public key file.");
} else if (pubkeyfile != NULL) {
ERR_load_crypto_strings();
}
#else
if (pubkeyfile != NULL)
errx(EX_UNAVAILABLE,"Unable to use the public key."
" Recompile dumpon with OpenSSL support.");
#endif
if (server != NULL && client != NULL) {
dev = _PATH_NETDUMP;
netdump = true;
} else if (server == NULL && client == NULL && argc > 0) {
if (strcmp(argv[0], "off") == 0) {
rflag = true;
dev = _PATH_DEVNULL;
} else
dev = argv[0];
netdump = false;
if (strcmp(dev, _PATH_DEVNULL) == 0) {
/*
* Netdump has its own configuration tracking that
* is not removed when using /dev/null.
*/
fd = open(_PATH_NETDUMP, O_RDONLY);
if (fd != -1) {
bzero(&ndconf, sizeof(ndconf));
ndconf.kda_index = KDA_REMOVE_ALL;
ndconf.kda_af = AF_INET;
error = ioctl(fd, DIOCSKERNELDUMP, &ndconf);
if (error != 0)
err(1, "ioctl(%s, DIOCSKERNELDUMP)",
_PATH_NETDUMP);
close(fd);
}
}
} else
usage();
fd = opendumpdev(dev, dumpdev);
if (!netdump && !gzip && !zstd && !rflag)
check_size(fd, dumpdev);
kdap = &ndconf;
bzero(kdap, sizeof(*kdap));
if (rflag)
kdap->kda_index = KDA_REMOVE;
else
kdap->kda_index = ins_idx;
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) {
if (error == EAI_SYSTEM)
err(EX_OSERR, "%s", gai_strerror(error));
errx(EX_NOHOST, "%s", gai_strerror(error));
}
server = inet_ntoa(
((struct sockaddr_in *)(void *)res->ai_addr)->sin_addr);
freeaddrinfo(res);
if (strlcpy(ndconf.kda_iface, argv[0],
sizeof(ndconf.kda_iface)) >= sizeof(ndconf.kda_iface))
errx(EX_USAGE, "invalid interface name '%s'", argv[0]);
if (inet_aton(server, &ndconf.kda_server.in4) == 0)
errx(EX_USAGE, "invalid server address '%s'", server);
if (inet_aton(client, &ndconf.kda_client.in4) == 0)
errx(EX_USAGE, "invalid client address '%s'", client);
if (gateway == NULL) {
gateway = find_gateway(argv[0]);
if (gateway == NULL) {
if (verbose)
printf(
"failed to look up gateway for %s\n",
server);
gateway = server;
}
}
if (inet_aton(gateway, &ndconf.kda_gateway.in4) == 0)
errx(EX_USAGE, "invalid gateway address '%s'", gateway);
ndconf.kda_af = AF_INET;
}
#ifdef HAVE_CRYPTO
if (pubkeyfile != NULL) {
kdap->kda_encryption = cipher;
genkey(pubkeyfile, kdap);
}
#endif
error = ioctl(fd, DIOCSKERNELDUMP, kdap);
if (error != 0)
error = errno;
if (error == EINVAL && (gzip || zstd)) {
/* Retry without compression in case kernel lacks support. */
kdap->kda_compression = KERNELDUMP_COMP_NONE;
error = ioctl(fd, DIOCSKERNELDUMP, kdap);
if (error == 0)
warnx("Compression disabled; kernel may lack gzip or zstd support.");
else
error = errno;
}
/* Emit a warning if the user configured a downed interface. */
if (error == 0 && netdump)
check_link_status(kdap->kda_iface);
explicit_bzero(kdap->kda_encryptedkey, kdap->kda_encryptedkeysize);
free(kdap->kda_encryptedkey);
explicit_bzero(kdap, sizeof(*kdap));
if (error != 0) {
if (netdump) {
/*
* Be slightly less user-hostile for some common
* errors, especially as users don't have any great
* discoverability into which NICs support netdump.
*/
if (error == ENODEV)
errx(EX_OSERR, "Unable to configure netdump "
"because the interface driver does not yet "
"support netdump.");
}
errc(EX_OSERR, error, "ioctl(DIOCSKERNELDUMP)");
}
if (verbose)
listdumpdev();
exit(EX_OK);
}