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IABSD.fr/src/usr.bin/ssh/ssh-keyscan.c
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djm
- usr.bin/ssh/ssh-keyscan.c
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/* $OpenBSD: ssh-keyscan.c,v 1.158 2024/06/14 00:25:25 djm Exp $ */ /* * Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>. * * Modification and redistribution in source and binary forms is * permitted provided that due credit is given to the author and the * OpenBSD project by leaving this copyright notice intact. */ #include <sys/types.h> #include <sys/socket.h> #include <sys/queue.h> #include <sys/time.h> #include <sys/resource.h> #ifdef WITH_OPENSSL #include <openssl/bn.h> #endif #include <errno.h> #include <limits.h> #include <netdb.h> #include <stdarg.h> #include <stdio.h> #include <stdlib.h> #include <poll.h> #include <signal.h> #include <string.h> #include <unistd.h> #include "xmalloc.h" #include "ssh.h" #include "sshbuf.h" #include "sshkey.h" #include "cipher.h" #include "digest.h" #include "kex.h" #include "compat.h" #include "myproposal.h" #include "packet.h" #include "dispatch.h" #include "log.h" #include "atomicio.h" #include "misc.h" #include "hostfile.h" #include "ssherr.h" #include "ssh_api.h" #include "dns.h" #include "addr.h" /* Flag indicating whether IPv4 or IPv6. This can be set on the command line. Default value is AF_UNSPEC means both IPv4 and IPv6. */ int IPv4or6 = AF_UNSPEC; int ssh_port = SSH_DEFAULT_PORT; #define KT_DSA (1) #define KT_RSA (1<<1) #define KT_ECDSA (1<<2) #define KT_ED25519 (1<<3) #define KT_XMSS (1<<4) #define KT_ECDSA_SK (1<<5) #define KT_ED25519_SK (1<<6) #define KT_MIN KT_DSA #define KT_MAX KT_ED25519_SK int get_cert = 0; int get_keytypes = KT_RSA|KT_ECDSA|KT_ED25519|KT_ECDSA_SK|KT_ED25519_SK; int hash_hosts = 0; /* Hash hostname on output */ int print_sshfp = 0; /* Print SSHFP records instead of known_hosts */ int found_one = 0; /* Successfully found a key */ int hashalg = -1; /* Hash for SSHFP records or -1 for all */ int quiet = 0; /* Don't print key comment lines */ #define MAXMAXFD 256 /* The number of seconds after which to give up on a TCP connection */ int timeout = 5; int maxfd; #define MAXCON (maxfd - 10) extern char *__progname; struct pollfd *read_wait; int ncon; /* * Keep a connection structure for each file descriptor. The state * associated with file descriptor n is held in fdcon[n]. */ typedef struct Connection { u_char c_status; /* State of connection on this file desc. */ #define CS_UNUSED 0 /* File descriptor unused */ #define CS_CON 1 /* Waiting to connect/read greeting */ int c_fd; /* Quick lookup: c->c_fd == c - fdcon */ int c_keytype; /* Only one of KT_* */ sig_atomic_t c_done; /* SSH2 done */ char *c_namebase; /* Address to free for c_name and c_namelist */ char *c_name; /* Hostname of connection for errors */ char *c_namelist; /* Pointer to other possible addresses */ char *c_output_name; /* Hostname of connection for output */ struct ssh *c_ssh; /* SSH-connection */ struct timespec c_ts; /* Time at which connection gets aborted */ TAILQ_ENTRY(Connection) c_link; /* List of connections in timeout order. */ } con; TAILQ_HEAD(conlist, Connection) tq; /* Timeout Queue */ con *fdcon; static void keyprint(con *c, struct sshkey *key); static int fdlim_get(int hard) { struct rlimit rlfd; if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1) return (-1); if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY || (hard ? rlfd.rlim_max : rlfd.rlim_cur) > INT_MAX) return sysconf(_SC_OPEN_MAX); return hard ? rlfd.rlim_max : rlfd.rlim_cur; } static int fdlim_set(int lim) { struct rlimit rlfd; if (lim <= 0) return (-1); if (getrlimit(RLIMIT_NOFILE, &rlfd) == -1) return (-1); rlfd.rlim_cur = lim; if (setrlimit(RLIMIT_NOFILE, &rlfd) == -1) return (-1); return (0); } /* * This is an strsep function that returns a null field for adjacent * separators. This is the same as the 4.4BSD strsep, but different from the * one in the GNU libc. */ static char * xstrsep(char **str, const char *delim) { char *s, *e; if (!**str) return (NULL); s = *str; e = s + strcspn(s, delim); if (*e != '\0') *e++ = '\0'; *str = e; return (s); } /* * Get the next non-null token (like GNU strsep). Strsep() will return a * null token for two adjacent separators, so we may have to loop. */ static char * strnnsep(char **stringp, char *delim) { char *tok; do { tok = xstrsep(stringp, delim); } while (tok && *tok == '\0'); return (tok); } static int key_print_wrapper(struct sshkey *hostkey, struct ssh *ssh) { con *c; if ((c = ssh_get_app_data(ssh)) != NULL) keyprint(c, hostkey); /* always abort key exchange */ return -1; } static int ssh2_capable(int remote_major, int remote_minor) { switch (remote_major) { case 1: if (remote_minor == 99) return 1; break; case 2: return 1; default: break; } return 0; } static void keygrab_ssh2(con *c) { char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; int r; switch (c->c_keytype) { case KT_DSA: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ? "ssh-dss-cert-v01@openssh.com" : "ssh-dss"; break; case KT_RSA: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ? "rsa-sha2-512-cert-v01@openssh.com," "rsa-sha2-256-cert-v01@openssh.com," "ssh-rsa-cert-v01@openssh.com" : "rsa-sha2-512," "rsa-sha2-256," "ssh-rsa"; break; case KT_ED25519: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ? "ssh-ed25519-cert-v01@openssh.com" : "ssh-ed25519"; break; case KT_XMSS: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ? "ssh-xmss-cert-v01@openssh.com" : "ssh-xmss@openssh.com"; break; case KT_ECDSA: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ? "ecdsa-sha2-nistp256-cert-v01@openssh.com," "ecdsa-sha2-nistp384-cert-v01@openssh.com," "ecdsa-sha2-nistp521-cert-v01@openssh.com" : "ecdsa-sha2-nistp256," "ecdsa-sha2-nistp384," "ecdsa-sha2-nistp521"; break; case KT_ECDSA_SK: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ? "sk-ecdsa-sha2-nistp256-cert-v01@openssh.com" : "sk-ecdsa-sha2-nistp256@openssh.com"; break; case KT_ED25519_SK: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = get_cert ? "sk-ssh-ed25519-cert-v01@openssh.com" : "sk-ssh-ed25519@openssh.com"; break; default: fatal("unknown key type %d", c->c_keytype); break; } if ((r = kex_setup(c->c_ssh, myproposal)) != 0) { free(c->c_ssh); fprintf(stderr, "kex_setup: %s\n", ssh_err(r)); exit(1); } #ifdef WITH_OPENSSL c->c_ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client; c->c_ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client; c->c_ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client; c->c_ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client; c->c_ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client; c->c_ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; c->c_ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; c->c_ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; #endif c->c_ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; c->c_ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; ssh_set_verify_host_key_callback(c->c_ssh, key_print_wrapper); /* * do the key-exchange until an error occurs or until * the key_print_wrapper() callback sets c_done. */ ssh_dispatch_run(c->c_ssh, DISPATCH_BLOCK, &c->c_done); } static void keyprint_one(const char *host, struct sshkey *key) { char *hostport = NULL, *hashed = NULL; const char *known_host; int r = 0; found_one = 1; if (print_sshfp) { export_dns_rr(host, key, stdout, 0, hashalg); return; } hostport = put_host_port(host, ssh_port); lowercase(hostport); if (hash_hosts && (hashed = host_hash(hostport, NULL, 0)) == NULL) fatal("host_hash failed"); known_host = hash_hosts ? hashed : hostport; if (!get_cert) r = fprintf(stdout, "%s ", known_host); if (r >= 0 && sshkey_write(key, stdout) == 0) (void)fputs("\n", stdout); free(hashed); free(hostport); } static void keyprint(con *c, struct sshkey *key) { char *hosts = c->c_output_name ? c->c_output_name : c->c_name; char *host, *ohosts; if (key == NULL) return; if (get_cert || (!hash_hosts && ssh_port == SSH_DEFAULT_PORT)) { keyprint_one(hosts, key); return; } ohosts = hosts = xstrdup(hosts); while ((host = strsep(&hosts, ",")) != NULL) keyprint_one(host, key); free(ohosts); } static int tcpconnect(char *host) { struct addrinfo hints, *ai, *aitop; char strport[NI_MAXSERV]; int gaierr, s = -1; snprintf(strport, sizeof strport, "%d", ssh_port); memset(&hints, 0, sizeof(hints)); hints.ai_family = IPv4or6; hints.ai_socktype = SOCK_STREAM; if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) { error("getaddrinfo %s: %s", host, ssh_gai_strerror(gaierr)); return -1; } for (ai = aitop; ai; ai = ai->ai_next) { s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); if (s == -1) { error("socket: %s", strerror(errno)); continue; } if (set_nonblock(s) == -1) fatal_f("set_nonblock(%d)", s); if (connect(s, ai->ai_addr, ai->ai_addrlen) == -1 && errno != EINPROGRESS) error("connect (`%s'): %s", host, strerror(errno)); else break; close(s); s = -1; } freeaddrinfo(aitop); return s; } static int conalloc(const char *iname, const char *oname, int keytype) { char *namebase, *name, *namelist; int s; namebase = namelist = xstrdup(iname); do { name = xstrsep(&namelist, ","); if (!name) { free(namebase); return (-1); } } while ((s = tcpconnect(name)) < 0); if (s >= maxfd) fatal("conalloc: fdno %d too high", s); if (fdcon[s].c_status) fatal("conalloc: attempt to reuse fdno %d", s); debug3_f("oname %s kt %d", oname, keytype); fdcon[s].c_fd = s; fdcon[s].c_status = CS_CON; fdcon[s].c_namebase = namebase; fdcon[s].c_name = name; fdcon[s].c_namelist = namelist; fdcon[s].c_output_name = xstrdup(oname); fdcon[s].c_keytype = keytype; monotime_ts(&fdcon[s].c_ts); fdcon[s].c_ts.tv_sec += timeout; TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link); read_wait[s].fd = s; read_wait[s].events = POLLIN; ncon++; return (s); } static void confree(int s) { if (s >= maxfd || fdcon[s].c_status == CS_UNUSED) fatal("confree: attempt to free bad fdno %d", s); free(fdcon[s].c_namebase); free(fdcon[s].c_output_name); fdcon[s].c_status = CS_UNUSED; fdcon[s].c_keytype = 0; if (fdcon[s].c_ssh) { ssh_packet_close(fdcon[s].c_ssh); free(fdcon[s].c_ssh); fdcon[s].c_ssh = NULL; } else close(s); TAILQ_REMOVE(&tq, &fdcon[s], c_link); read_wait[s].fd = -1; read_wait[s].events = 0; ncon--; } static int conrecycle(int s) { con *c = &fdcon[s]; int ret; ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype); confree(s); return (ret); } static void congreet(int s) { int n = 0, remote_major = 0, remote_minor = 0; char buf[256], *cp; char remote_version[sizeof buf]; size_t bufsiz; con *c = &fdcon[s]; /* send client banner */ n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n", PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2); if (n < 0 || (size_t)n >= sizeof(buf)) { error("snprintf: buffer too small"); confree(s); return; } if (atomicio(vwrite, s, buf, n) != (size_t)n) { error("write (%s): %s", c->c_name, strerror(errno)); confree(s); return; } /* * Read the server banner as per RFC4253 section 4.2. The "SSH-" * protocol identification string may be preceded by an arbitrarily * large banner which we must read and ignore. Loop while reading * newline-terminated lines until we have one starting with "SSH-". * The ID string cannot be longer than 255 characters although the * preceding banner lines may (in which case they'll be discarded * in multiple iterations of the outer loop). */ for (;;) { memset(buf, '\0', sizeof(buf)); bufsiz = sizeof(buf); cp = buf; while (bufsiz-- && (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') { if (*cp == '\r') *cp = '\n'; cp++; } if (n != 1 || strncmp(buf, "SSH-", 4) == 0) break; } if (n == 0) { switch (errno) { case EPIPE: error("%s: Connection closed by remote host", c->c_name); break; case ECONNREFUSED: break; default: error("read (%s): %s", c->c_name, strerror(errno)); break; } conrecycle(s); return; } if (cp >= buf + sizeof(buf)) { error("%s: greeting exceeds allowable length", c->c_name); confree(s); return; } if (*cp != '\n' && *cp != '\r') { error("%s: bad greeting", c->c_name); confree(s); return; } *cp = '\0'; if ((c->c_ssh = ssh_packet_set_connection(NULL, s, s)) == NULL) fatal("ssh_packet_set_connection failed"); ssh_packet_set_timeout(c->c_ssh, timeout, 1); ssh_set_app_data(c->c_ssh, c); /* back link */ c->c_ssh->compat = 0; if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, remote_version) == 3) compat_banner(c->c_ssh, remote_version); if (!ssh2_capable(remote_major, remote_minor)) { debug("%s doesn't support ssh2", c->c_name); confree(s); return; } if (!quiet) { fprintf(stdout, "%c %s:%d %s\n", print_sshfp ? ';' : '#', c->c_name, ssh_port, chop(buf)); } keygrab_ssh2(c); confree(s); } static void conread(int s) { con *c = &fdcon[s]; if (c->c_status != CS_CON) fatal("conread: invalid status %d", c->c_status); congreet(s); } static void conloop(void) { struct timespec seltime, now; con *c; int i; monotime_ts(&now); c = TAILQ_FIRST(&tq); if (c && timespeccmp(&c->c_ts, &now, >)) timespecsub(&c->c_ts, &now, &seltime); else timespecclear(&seltime); while (ppoll(read_wait, maxfd, &seltime, NULL) == -1) { if (errno == EAGAIN || errno == EINTR) continue; error("poll error"); } for (i = 0; i < maxfd; i++) { if (read_wait[i].revents & (POLLHUP|POLLERR|POLLNVAL)) confree(i); else if (read_wait[i].revents & (POLLIN|POLLHUP)) conread(i); } c = TAILQ_FIRST(&tq); while (c && timespeccmp(&c->c_ts, &now, <)) { int s = c->c_fd; c = TAILQ_NEXT(c, c_link); conrecycle(s); } } static void do_one_host(char *host) { char *name = strnnsep(&host, " \t\n"); int j; if (name == NULL) return; for (j = KT_MIN; j <= KT_MAX; j *= 2) { if (get_keytypes & j) { while (ncon >= MAXCON) conloop(); conalloc(name, *host ? host : name, j); } } } static void do_host(char *host) { char daddr[128]; struct xaddr addr, end_addr; u_int masklen; if (host == NULL) return; if (addr_pton_cidr(host, &addr, &masklen) != 0) { /* Assume argument is a hostname */ do_one_host(host); } else { /* Argument is a CIDR range */ debug("CIDR range %s", host); end_addr = addr; if (addr_host_to_all1s(&end_addr, masklen) != 0) goto badaddr; /* * Note: we deliberately include the all-zero/ones addresses. */ for (;;) { if (addr_ntop(&addr, daddr, sizeof(daddr)) != 0) { badaddr: error("Invalid address %s", host); return; } debug("CIDR expand: address %s", daddr); do_one_host(daddr); if (addr_cmp(&addr, &end_addr) == 0) break; addr_increment(&addr); }; } } void sshfatal(const char *file, const char *func, int line, int showfunc, LogLevel level, const char *suffix, const char *fmt, ...) { va_list args; va_start(args, fmt); sshlogv(file, func, line, showfunc, level, suffix, fmt, args); va_end(args); cleanup_exit(255); } static void usage(void) { fprintf(stderr, "usage: ssh-keyscan [-46cDHqv] [-f file] [-O option] [-p port] [-T timeout]\n" " [-t type] [host | addrlist namelist]\n"); exit(1); } int main(int argc, char **argv) { int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO; int opt, fopt_count = 0, j; char *tname, *cp, *line = NULL; size_t linesize = 0; FILE *fp; extern int optind; extern char *optarg; TAILQ_INIT(&tq); /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ sanitise_stdfd(); if (argc <= 1) usage(); while ((opt = getopt(argc, argv, "cDHqv46O:p:T:t:f:")) != -1) { switch (opt) { case 'H': hash_hosts = 1; break; case 'c': get_cert = 1; break; case 'D': print_sshfp = 1; break; case 'p': ssh_port = a2port(optarg); if (ssh_port <= 0) { fprintf(stderr, "Bad port '%s'\n", optarg); exit(1); } break; case 'T': timeout = convtime(optarg); if (timeout == -1 || timeout == 0) { fprintf(stderr, "Bad timeout '%s'\n", optarg); usage(); } break; case 'v': if (!debug_flag) { debug_flag = 1; log_level = SYSLOG_LEVEL_DEBUG1; } else if (log_level < SYSLOG_LEVEL_DEBUG3) log_level++; else fatal("Too high debugging level."); break; case 'q': quiet = 1; break; case 'f': if (strcmp(optarg, "-") == 0) optarg = NULL; argv[fopt_count++] = optarg; break; case 'O': /* Maybe other misc options in the future too */ if (strncmp(optarg, "hashalg=", 8) != 0) fatal("Unsupported -O option"); if ((hashalg = ssh_digest_alg_by_name( optarg + 8)) == -1) fatal("Unsupported hash algorithm"); break; case 't': get_keytypes = 0; tname = strtok(optarg, ","); while (tname) { int type = sshkey_type_from_name(tname); switch (type) { #ifdef WITH_DSA case KEY_DSA: get_keytypes |= KT_DSA; break; #endif case KEY_ECDSA: get_keytypes |= KT_ECDSA; break; case KEY_RSA: get_keytypes |= KT_RSA; break; case KEY_ED25519: get_keytypes |= KT_ED25519; break; case KEY_XMSS: get_keytypes |= KT_XMSS; break; case KEY_ED25519_SK: get_keytypes |= KT_ED25519_SK; break; case KEY_ECDSA_SK: get_keytypes |= KT_ECDSA_SK; break; case KEY_UNSPEC: default: fatal("Unknown key type \"%s\"", tname); } tname = strtok(NULL, ","); } break; case '4': IPv4or6 = AF_INET; break; case '6': IPv4or6 = AF_INET6; break; default: usage(); } } if (optind == argc && !fopt_count) usage(); log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1); maxfd = fdlim_get(1); if (maxfd < 0) fatal("%s: fdlim_get: bad value", __progname); if (maxfd > MAXMAXFD) maxfd = MAXMAXFD; if (MAXCON <= 0) fatal("%s: not enough file descriptors", __progname); if (maxfd > fdlim_get(0)) fdlim_set(maxfd); fdcon = xcalloc(maxfd, sizeof(con)); read_wait = xcalloc(maxfd, sizeof(struct pollfd)); for (j = 0; j < maxfd; j++) read_wait[j].fd = -1; for (j = 0; j < fopt_count; j++) { if (argv[j] == NULL) fp = stdin; else if ((fp = fopen(argv[j], "r")) == NULL) fatal("%s: %s: %s", __progname, fp == stdin ? "<stdin>" : argv[j], strerror(errno)); while (getline(&line, &linesize, fp) != -1) { /* Chomp off trailing whitespace and comments */ if ((cp = strchr(line, '#')) == NULL) cp = line + strlen(line) - 1; while (cp >= line) { if (*cp == ' ' || *cp == '\t' || *cp == '\n' || *cp == '#') *cp-- = '\0'; else break; } /* Skip empty lines */ if (*line == '\0') continue; do_host(line); } if (ferror(fp)) fatal("%s: %s: %s", __progname, fp == stdin ? "<stdin>" : argv[j], strerror(errno)); if (fp != stdin) fclose(fp); } free(line); while (optind < argc) do_host(argv[optind++]); while (ncon > 0) conloop(); return found_one ? 0 : 1; }