From bdffbcdc82c1a8926fdd441e4ccba658486df3ec Mon Sep 17 00:00:00 2001 From: djm Date: Tue, 1 Mar 2005 10:48:35 +0000 Subject: [PATCH] - djm@cvs.openbsd.org 2005/03/01 10:42:49 [ssh-keygen.1 ssh-keygen.c ssh_config.5] add tools for managing known_hosts files with hashed hostnames, including hashing existing files and deleting hosts by name; ok markus@ deraadt@ --- ChangeLog | 4 + ssh-keygen.1 | 43 +++++++++- ssh-keygen.c | 228 ++++++++++++++++++++++++++++++++++++++++++++++++--- ssh_config.5 | 5 +- 4 files changed, 267 insertions(+), 13 deletions(-) diff --git a/ChangeLog b/ChangeLog index 61e092d5..00035db7 100644 --- a/ChangeLog +++ b/ChangeLog @@ -36,6 +36,10 @@ - djm@cvs.openbsd.org 2005/03/01 10:41:28 [ssh-keyscan.1 ssh-keyscan.c] option to hash hostnames output by ssh-keyscan; ok markus@ deraadt@ + - djm@cvs.openbsd.org 2005/03/01 10:42:49 + [ssh-keygen.1 ssh-keygen.c ssh_config.5] + add tools for managing known_hosts files with hashed hostnames, including + hashing existing files and deleting hosts by name; ok markus@ deraadt@ 20050226 - (dtucker) [openbsd-compat/bsd-openpty.c openbsd-compat/inet_ntop.c] diff --git a/ssh-keygen.1 b/ssh-keygen.1 index c0f24dcd..f4c5ebcb 100644 --- a/ssh-keygen.1 +++ b/ssh-keygen.1 @@ -1,4 +1,4 @@ -.\" $OpenBSD: ssh-keygen.1,v 1.63 2004/08/13 00:01:43 jmc Exp $ +.\" $OpenBSD: ssh-keygen.1,v 1.64 2005/03/01 10:42:49 djm Exp $ .\" .\" -*- nroff -*- .\" @@ -81,6 +81,15 @@ .Nm ssh-keygen .Fl D Ar reader .Nm ssh-keygen +.Fl F Ar hostname +.Op Fl f Ar known_hosts_file +.Nm ssh-keygen +.Fl H +.Op Fl f Ar known_hosts_file +.Nm ssh-keygen +.Fl R Ar hostname +.Op Fl f Ar known_hosts_file +.Nm ssh-keygen .Fl U Ar reader .Op Fl f Ar input_keyfile .Nm ssh-keygen @@ -243,6 +252,38 @@ Provides the new comment. .It Fl D Ar reader Download the RSA public key stored in the smartcard in .Ar reader . +.It Fl F Ar hostname +Search for the specified +.Ar hostname +in a +.Pa known_hosts +file, listing any occurances found. +This option is useful to find hashed host names or addresses and may also be +used in conjunction with the +.Fl H +option to print found keys in a hashed format. +.It Fl H +Hash a +.Pa known_hosts +file, printing the result to standard output. +This replaces all hostnames and addresses with hashed representations. +These hashes may be used normally by +.Nm ssh +and +.Nm sshd , +but they do not reveal identifying information should the file's contents +be disclosed. +This option will not modify existing hashed hostnames and is therefore safe +to use on files that mix hashed and non-hashed names. +.It Fl R Ar hostname +Removes all keys belonging to +.Ar hostname +from a +.Pa known_hosts +file. +This option is useful to delete hashed hosts (see the +.Fl H +option above). .It Fl G Ar output_file Generate candidate primes for DH-GEX. These primes must be screened for diff --git a/ssh-keygen.c b/ssh-keygen.c index 7ed62a30..00ddb90c 100644 --- a/ssh-keygen.c +++ b/ssh-keygen.c @@ -12,7 +12,7 @@ */ #include "includes.h" -RCSID("$OpenBSD: ssh-keygen.c,v 1.118 2004/12/23 17:38:07 markus Exp $"); +RCSID("$OpenBSD: ssh-keygen.c,v 1.119 2005/03/01 10:42:49 djm Exp $"); #include #include @@ -27,6 +27,8 @@ RCSID("$OpenBSD: ssh-keygen.c,v 1.118 2004/12/23 17:38:07 markus Exp $"); #include "pathnames.h" #include "log.h" #include "misc.h" +#include "match.h" +#include "hostfile.h" #ifdef SMARTCARD #include "scard.h" @@ -50,6 +52,13 @@ int change_comment = 0; int quiet = 0; +/* Flag indicating that we want to hash a known_hosts file */ +int hash_hosts = 0; +/* Flag indicating that we want lookup a host in known_hosts file */ +int find_host = 0; +/* Flag indicating that we want to delete a host from a known_hosts file */ +int delete_host = 0; + /* Flag indicating that we just want to see the key fingerprint */ int print_fingerprint = 0; int print_bubblebabble = 0; @@ -541,6 +550,194 @@ do_fingerprint(struct passwd *pw) exit(0); } +static void +print_host(FILE *f, char *name, Key *public, int hash) +{ + if (hash && (name = host_hash(name, NULL, 0)) == NULL) + fatal("hash_host failed"); + fprintf(f, "%s ", name); + if (!key_write(public, f)) + fatal("key_write failed"); + fprintf(f, "\n"); +} + +static void +do_known_hosts(struct passwd *pw, const char *name) +{ + FILE *in, *out = stdout; + Key *public; + char *cp, *cp2, *kp, *kp2; + char line[16*1024], tmp[MAXPATHLEN], old[MAXPATHLEN]; + int c, i, skip = 0, inplace = 0, num = 0, invalid = 0, has_unhashed = 0; + + if (!have_identity) { + cp = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid); + if (strlcpy(identity_file, cp, sizeof(identity_file)) >= + sizeof(identity_file)) + fatal("Specified known hosts path too long"); + xfree(cp); + have_identity = 1; + } + if ((in = fopen(identity_file, "r")) == NULL) + fatal("fopen: %s", strerror(errno)); + + /* + * Find hosts goes to stdout, hash and deletions happen in-place + * A corner case is ssh-keygen -HF foo, which should go to stdout + */ + if (!find_host && (hash_hosts || delete_host)) { + if (strlcpy(tmp, identity_file, sizeof(tmp)) >= sizeof(tmp) || + strlcat(tmp, ".XXXXXXXXXX", sizeof(tmp)) >= sizeof(tmp) || + strlcpy(old, identity_file, sizeof(old)) >= sizeof(old) || + strlcat(old, ".old", sizeof(old)) >= sizeof(old)) + fatal("known_hosts path too long"); + umask(077); + if ((c = mkstemp(tmp)) == -1) + fatal("mkstemp: %s", strerror(errno)); + if ((out = fdopen(c, "w")) == NULL) { + c = errno; + unlink(tmp); + fatal("fdopen: %s", strerror(c)); + } + inplace = 1; + } + + while (fgets(line, sizeof(line), in)) { + num++; + i = strlen(line) - 1; + if (line[i] != '\n') { + error("line %d too long: %.40s...", num, line); + skip = 1; + invalid = 1; + continue; + } + if (skip) { + skip = 0; + continue; + } + line[i] = '\0'; + + /* Skip leading whitespace, empty and comment lines. */ + for (cp = line; *cp == ' ' || *cp == '\t'; cp++) + ; + if (!*cp || *cp == '\n' || *cp == '#') { + if (inplace) + fprintf(out, "%s\n", cp); + continue; + } + /* Find the end of the host name portion. */ + for (kp = cp; *kp && *kp != ' ' && *kp != '\t'; kp++) + ; + if (*kp == '\0' || *(kp + 1) == '\0') { + error("line %d missing key: %.40s...", + num, line); + invalid = 1; + continue; + } + *kp++ = '\0'; + kp2 = kp; + + public = key_new(KEY_RSA1); + if (key_read(public, &kp) != 1) { + kp = kp2; + key_free(public); + public = key_new(KEY_UNSPEC); + if (key_read(public, &kp) != 1) { + error("line %d invalid key: %.40s...", + num, line); + key_free(public); + invalid = 1; + continue; + } + } + + if (*cp == HASH_DELIM) { + if (find_host || delete_host) { + cp2 = host_hash(name, cp, strlen(cp)); + if (cp2 == NULL) { + error("line %d: invalid hashed " + "name: %.64s...", num, line); + invalid = 1; + continue; + } + c = (strcmp(cp2, cp) == 0); + if (find_host && c) { + printf("# Host %s found: " + "line %d type %s\n", name, + num, key_type(public)); + print_host(out, cp, public, 0); + } + if (delete_host && !c) + print_host(out, cp, public, 0); + } else if (hash_hosts) + print_host(out, cp, public, 0); + } else { + if (find_host || delete_host) { + c = (match_hostname(name, cp, + strlen(cp)) == 1); + if (find_host && c) { + printf("# Host %s found: " + "line %d type %s\n", name, + num, key_type(public)); + print_host(out, cp, public, hash_hosts); + } + if (delete_host && !c) + print_host(out, cp, public, 0); + } else if (hash_hosts) { + for(cp2 = strsep(&cp, ","); + cp2 != NULL && *cp2 != '\0'; + cp2 = strsep(&cp, ",")) + print_host(out, cp2, public, 1); + has_unhashed = 1; + } + } + key_free(public); + } + fclose(in); + + if (invalid) { + fprintf(stderr, "%s is not a valid known_host file.\n", + identity_file); + if (inplace) { + fprintf(stderr, "Not replacing existing known_hosts " + "file beacuse of errors"); + fclose(out); + unlink(tmp); + } + exit(1); + } + + if (inplace) { + fclose(out); + + /* Backup existing file */ + if (unlink(old) == -1 && errno != ENOENT) + fatal("unlink %.100s: %s", old, strerror(errno)); + if (link(identity_file, old) == -1) + fatal("link %.100s to %.100s: %s", identity_file, old, + strerror(errno)); + /* Move new one into place */ + if (rename(tmp, identity_file) == -1) { + error("rename\"%s\" to \"%s\": %s", tmp, identity_file, + strerror(errno)); + unlink(tmp); + unlink(old); + exit(1); + } + + fprintf(stderr, "%s updated.\n", identity_file); + fprintf(stderr, "Original contents retained as %s\n", old); + if (has_unhashed) { + fprintf(stderr, "WARNING: %s contains unhashed " + "entries\n", old); + fprintf(stderr, "Delete this file to ensure privacy " + "of hostnames\n"); + } + } + + exit(0); +} + /* * Perform changing a passphrase. The argument is the passwd structure * for the current user. @@ -767,6 +964,8 @@ usage(void) fprintf(stderr, " -y Read private key file and print public key.\n"); fprintf(stderr, " -t type Specify type of key to create.\n"); fprintf(stderr, " -B Show bubblebabble digest of key file.\n"); + fprintf(stderr, " -H Hash names in known_hosts file\n"); + fprintf(stderr, " -F hostname Find hostname in known hosts file\n"); fprintf(stderr, " -C comment Provide new comment.\n"); fprintf(stderr, " -N phrase Provide new passphrase.\n"); fprintf(stderr, " -P phrase Provide old passphrase.\n"); @@ -790,7 +989,7 @@ main(int ac, char **av) { char dotsshdir[MAXPATHLEN], comment[1024], *passphrase1, *passphrase2; char out_file[MAXPATHLEN], *reader_id = NULL; - char *resource_record_hostname = NULL; + char *rr_hostname = NULL; Key *private, *public; struct passwd *pw; struct stat st; @@ -824,7 +1023,7 @@ main(int ac, char **av) } while ((opt = getopt(ac, av, - "degiqpclBRvxXyb:f:t:U:D:P:N:C:r:g:T:G:M:S:a:W:")) != -1) { + "degiqpclBHvxXyF:b:f:t:U:D:P:N:C:r:g:R:T:G:M:S:a:W:")) != -1) { switch (opt) { case 'b': bits = atoi(optarg); @@ -833,6 +1032,17 @@ main(int ac, char **av) exit(1); } break; + case 'F': + find_host = 1; + rr_hostname = optarg; + break; + case 'H': + hash_hosts = 1; + break; + case 'R': + delete_host = 1; + rr_hostname = optarg; + break; case 'l': print_fingerprint = 1; break; @@ -864,10 +1074,6 @@ main(int ac, char **av) case 'q': quiet = 1; break; - case 'R': - /* unused */ - exit(0); - break; case 'e': case 'x': /* export key */ @@ -902,7 +1108,7 @@ main(int ac, char **av) } break; case 'r': - resource_record_hostname = optarg; + rr_hostname = optarg; break; case 'W': generator_wanted = atoi(optarg); @@ -945,6 +1151,8 @@ main(int ac, char **av) printf("Can only have one of -p and -c.\n"); usage(); } + if (delete_host || hash_hosts || find_host) + do_known_hosts(pw, rr_hostname); if (print_fingerprint || print_bubblebabble) do_fingerprint(pw); if (change_passphrase) @@ -957,8 +1165,8 @@ main(int ac, char **av) do_convert_from_ssh2(pw); if (print_public) do_print_public(pw); - if (resource_record_hostname != NULL) { - do_print_resource_record(pw, resource_record_hostname); + if (rr_hostname != NULL) { + do_print_resource_record(pw, rr_hostname); } if (reader_id != NULL) { #ifdef SMARTCARD diff --git a/ssh_config.5 b/ssh_config.5 index 9077acbe..2a85485e 100644 --- a/ssh_config.5 +++ b/ssh_config.5 @@ -34,7 +34,7 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.\" $OpenBSD: ssh_config.5,v 1.44 2005/03/01 10:40:27 djm Exp $ +.\" $OpenBSD: ssh_config.5,v 1.45 2005/03/01 10:42:49 djm Exp $ .Dd September 25, 1999 .Dt SSH_CONFIG 5 .Os @@ -421,7 +421,8 @@ be disclosed. The default is .Dq no . Note that hashing of names and addresses will not be retrospectively applied -to existing known hosts files. +to existing known hosts files, but these may be manually hashed using +.Xr ssh-keygen 1 . .It Cm HostbasedAuthentication Specifies whether to try rhosts based authentication with public key authentication. -- 2.45.1