Hi, Thanks for this. Could I ask you to create a bug at https://bugzilla.mindrot.org/ and attach your patch there? We're pretty much closed for the 7.0 release ATM but we'll look at it once we're done. I guess something similar for ssh-add would make sense too... -d On Wed, 29 Jul 2015, Meghana Bhat wrote: > Allow users to specify certificates to be used for authentication on > the command line with the '-z' argument when running ssh. For > successful authentication, the key pair associated with the certificate > must also be presented during the ssh. > > Certificates may also be specified in ssh_config as a > CertificateFile. > > This option is meant the address the issue mentioned in the following > exchange: > http://lists.mindrot.org/pipermail/openssh-unix-dev/2013-September/031629.html > > Patch developed against 6.9p. > > --- > readconf.c | 48 +++++++++++++++++++ > readconf.h | 6 +++ > regress/Makefile | 1 + > regress/ssh-cert.sh | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > ssh.1 | 17 +++++++ > ssh.c | 85 +++++++++++++++++++++++++++++++- > ssh.h | 7 +++ > ssh_config.5 | 33 +++++++++++++ > sshconnect2.c | 47 ++++++++++++++++-- > 9 files changed, 375 insertions(+), 5 deletions(-) > create mode 100644 regress/ssh-cert.sh > > diff --git a/readconf.c b/readconf.c > index f1c860b..b34213d 100644 > --- a/readconf.c > +++ b/readconf.c > @@ -135,6 +135,7 @@ typedef enum { > oPasswordAuthentication, oRSAAuthentication, > oChallengeResponseAuthentication, oXAuthLocation, > oIdentityFile, oHostName, oPort, oCipher, oRemoteForward, oLocalForward, > + oCertificateFile, > oUser, oEscapeChar, oRhostsRSAAuthentication, oProxyCommand, > oGlobalKnownHostsFile, oUserKnownHostsFile, oConnectionAttempts, > oBatchMode, oCheckHostIP, oStrictHostKeyChecking, oCompression, > @@ -202,6 +203,7 @@ static struct { > { "identityfile", oIdentityFile }, > { "identityfile2", oIdentityFile }, /* obsolete */ > { "identitiesonly", oIdentitiesOnly }, > + { "certificatefile", oCertificateFile }, > { "hostname", oHostName }, > { "hostkeyalias", oHostKeyAlias }, > { "proxycommand", oProxyCommand }, > @@ -366,6 +368,37 @@ clear_forwardings(Options *options) > } > > void > +add_certificate_file(Options *options, const char *dir, const char *filename, > + int userprovided) > +{ > + char *path; > + int i; > + > + if (options->num_certificate_files >= SSH_MAX_CERTIFICATE_FILES) > + fatal("Too many certificate files specified (max %d)", > + SSH_MAX_CERTIFICATE_FILES); > + > + if (dir == NULL) /* no dir, filename is absolute */ > + path = xstrdup(filename); > + else > + (void)xasprintf(&path, "%.100s%.100s", dir, filename); > + > + /* Avoid registering duplicates */ > + for (i = 0; i < options->num_certificate_files; i++) { > + if (options->certificate_file_userprovided[i] == userprovided && > + strcmp(options->certificate_files[i], path) == 0) { > + debug2("%s: ignoring duplicate key %s", __func__, path); > + free(path); > + return; > + } > + } > + > + options->certificate_file_userprovided[options->num_certificate_files] = > + userprovided; > + options->certificate_files[options->num_certificate_files++] = path; > +} > + > +void > add_identity_file(Options *options, const char *dir, const char *filename, > int userprovided) > { > @@ -981,6 +1014,20 @@ parse_time: > } > break; > > + case oCertificateFile: > + arg = strdelim(&s); > + if (!arg || *arg == '\0') > + fatal("%.200s line %d: Missing argument.", filename, linenum); > + if (*activep) { > + intptr = &options->num_certificate_files; > + if (*intptr >= SSH_MAX_CERTIFICATE_FILES) > + fatal("%.200s line %d: Too many identity files specified (max %d).", > + filename, linenum, SSH_MAX_CERTIFICATE_FILES); > + add_certificate_file(options, NULL, > + arg, flags & SSHCONF_USERCONF); > + } > + break; > + > case oXAuthLocation: > charptr=&options->xauth_location; > goto parse_string; > @@ -1625,6 +1672,7 @@ initialize_options(Options * options) > options->hostkeyalgorithms = NULL; > options->protocol = SSH_PROTO_UNKNOWN; > options->num_identity_files = 0; > + options->num_certificate_files = 0; > options->hostname = NULL; > options->host_key_alias = NULL; > options->proxy_command = NULL; > diff --git a/readconf.h b/readconf.h > index bb2d552..f839016 100644 > --- a/readconf.h > +++ b/readconf.h > @@ -94,6 +94,11 @@ typedef struct { > char *identity_files[SSH_MAX_IDENTITY_FILES]; > int identity_file_userprovided[SSH_MAX_IDENTITY_FILES]; > struct sshkey *identity_keys[SSH_MAX_IDENTITY_FILES]; > + > + int num_certificate_files; /* Number of extra certificates for ssh. */ > + char *certificate_files[SSH_MAX_CERTIFICATE_FILES]; > + int certificate_file_userprovided[SSH_MAX_CERTIFICATE_FILES]; > + struct sshkey *certificates[SSH_MAX_CERTIFICATE_FILES]; > > /* Local TCP/IP forward requests. */ > int num_local_forwards; > @@ -194,5 +199,6 @@ void dump_client_config(Options *o, const char *host); > void add_local_forward(Options *, const struct Forward *); > void add_remote_forward(Options *, const struct Forward *); > void add_identity_file(Options *, const char *, const char *, int); > +void add_certificate_file(Options *, const char *, const char *, int); > > #endif /* READCONF_H */ > diff --git a/regress/Makefile b/regress/Makefile > index cba83f4..67455a8 100644 > --- a/regress/Makefile > +++ b/regress/Makefile > @@ -74,6 +74,7 @@ LTESTS= connect \ > hostkey-agent \ > keygen-knownhosts \ > hostkey-rotate \ > + ssh-cert \ > principals-command > > > diff --git a/regress/ssh-cert.sh b/regress/ssh-cert.sh > new file mode 100644 > index 0000000..152278b > --- /dev/null > +++ b/regress/ssh-cert.sh > @@ -0,0 +1,136 @@ > +# $OpenBSD: multicert.sh,v 1.1 2014/12/22 08:06:03 djm Exp $ > +# Placed in the Public Domain. > + > +tid="ssh with certificates" > + > +rm -f $OBJ/user_ca_key* $OBJ/user_key* > +rm -f $OBJ/cert_user_key* > + > +# Create a CA key > +${SSHKEYGEN} -q -N '' -t ed25519 -f $OBJ/user_ca_key1 ||\ > + fatal "ssh-keygen failed" > +${SSHKEYGEN} -q -N '' -t ed25519 -f $OBJ/user_ca_key2 ||\ > + fatal "ssh-keygen failed" > + > +# Make some keys and certificates. > +${SSHKEYGEN} -q -N '' -t ed25519 -f $OBJ/user_key1 || \ > + fatal "ssh-keygen failed" > +${SSHKEYGEN} -q -N '' -t ed25519 -f $OBJ/user_key2 || \ > + fatal "ssh-keygen failed" > +# Move the certificate to a different address to better control > +# when it is offered. > +${SSHKEYGEN} -q -s $OBJ/user_ca_key1 -I "regress user key for $USER" \ > + -z $$ -n ${USER} $OBJ/user_key1 || > + fail "couldn't sign user_key1 with user_ca_key1" > +mv $OBJ/user_key1-cert.pub $OBJ/cert_user_key1_1.pub > +${SSHKEYGEN} -q -s $OBJ/user_ca_key2 -I "regress user key for $USER" \ > + -z $$ -n ${USER} $OBJ/user_key1 || > + fail "couldn't sign user_key1 with user_ca_key2" > +mv $OBJ/user_key1-cert.pub $OBJ/cert_user_key1_2.pub > + > +trace 'try with identity files' > +opts="-F $OBJ/ssh_proxy -oIdentitiesOnly=yes" > +opts2="$opts -i $OBJ/user_key1 -i $OBJ/user_key2" > +echo "cert-authority $(cat $OBJ/user_ca_key1.pub)" > $OBJ/authorized_keys_$USER > + > +for p in ${SSH_PROTOCOLS}; do > + # Just keys should fail > + ${SSH} $opts2 somehost exit 5$p > + r=$? > + if [ $r -eq 5$p ]; then > + fail "ssh succeeded with no certs in protocol $p" > + fi > + > + # Keys with untrusted cert should fail. > + opts3="$opts2 -z $OBJ/cert_user_key1_2.pub" > + ${SSH} $opts3 somehost exit 5$p > + r=$? > + if [ $r -eq 5$p ]; then > + fail "ssh succeeded with bad cert in protocol $p" > + fi > + > + # Good cert with bad key should fail. > + opts3="$opts -i $OBJ/user_key2 -z $OBJ/cert_user_key1_1.pub" > + ${SSH} $opts3 somehost exit 5$p > + r=$? > + if [ $r -eq 5$p ]; then > + fail "ssh succeeded with no matching key in protocol $p" > + fi > + > + # Keys with one trusted cert, should succeed. > + opts3="$opts2 -z $OBJ/cert_user_key1_1.pub" > + ${SSH} $opts3 somehost exit 5$p > + r=$? > + if [ $r -ne 5$p ]; then > + fail "ssh failed with trusted cert and key in protocol $p" > + fi > + > + # Multiple certs and keys, with one trusted cert, should succeed. > + opts3="$opts2 -z $OBJ/cert_user_key1_2.pub -z $OBJ/cert_user_key1_1.pub" > + ${SSH} $opts3 somehost exit 5$p > + r=$? > + if [ $r -ne 5$p ]; then > + fail "ssh failed with multiple certs in protocol $p" > + fi > + > + #Keys with trusted certificate specified in config options, should succeed. > + opts3="$opts2 -oCertificateFile=$OBJ/cert_user_key1_1.pub" > + ${SSH} $opts3 somehost exit 5$p > + r=$? > + if [ $r -ne 5$p ]; then > + fail "ssh failed with trusted cert in config in protocol $p" > + fi > +done > + > +#next, using an agent in combination with the keys > +SSH_AUTH_SOCK=/nonexistent ${SSHADD} -l > /dev/null 2>&1 > +if [ $? -ne 2 ]; then > + fatal "ssh-add -l did not fail with exit code 2" > +fi > + > +trace "start agent" > +eval `${SSHAGENT} -s` > /dev/null > +r=$? > +if [ $r -ne 0 ]; then > + fatal "could not start ssh-agent: exit code $r" > +fi > + > +# add private keys to agent > +${SSHADD} -k $OBJ/user_key2 > /dev/null 2>&1 > +if [ $? -ne 0 ]; then > + fatal "ssh-add did not succeed with exit code 0" > +fi > +${SSHADD} -k $OBJ/user_key1 > /dev/null 2>&1 > +if [ $? -ne 0 ]; then > + fatal "ssh-add did not succeed with exit code 0" > +fi > + > +# try ssh with the agent and certificates > +# note: ssh agent only uses certificates in protocol 2 > +opts="-F $OBJ/ssh_proxy" > +# with no certificates, shoud fail > +${SSH} -2 $opts somehost exit 52 > +if [ $? -eq 52 ]; then > + fail "ssh connect with agent in protocol 2 succeeded with no cert" > +fi > + > +#with an untrusted certificate, should fail > +opts="$opts -z $OBJ/cert_user_key1_2.pub" > +${SSH} -2 $opts somehost exit 52 > +if [ $? -eq 52 ]; then > + fail "ssh connect with agent in protocol 2 succeeded with bad cert" > +fi > + > +#with an additional trusted certificate, should succeed > +opts="$opts -z $OBJ/cert_user_key1_1.pub" > +${SSH} -2 $opts somehost exit 52 > +if [ $? -ne 52 ]; then > + fail "ssh connect with agent in protocol 2 failed with good cert" > +fi > + > +trace "kill agent" > +${SSHAGENT} -k > /dev/null > + > +#cleanup > +rm -f $OBJ/user_ca_key* $OBJ/user_key* > +rm -f $OBJ/cert_user_key* > diff --git a/ssh.1 b/ssh.1 > index 2ea0a20..76a9459 100644 > --- a/ssh.1 > +++ b/ssh.1 > @@ -63,6 +63,7 @@ > .Op Fl S Ar ctl_path > .Op Fl W Ar host : Ns Ar port > .Op Fl w Ar local_tun Ns Op : Ns Ar remote_tun > +.Op Fl z Ar certificate_file > .Oo Ar user Ns @ Oc Ns Ar hostname > .Op Ar command > .Ek > @@ -468,6 +469,7 @@ For full details of the options listed below, and their possible values, see > .It CanonicalizeHostname > .It CanonicalizeMaxDots > .It CanonicalizePermittedCNAMEs > +.It CertificateFile > .It ChallengeResponseAuthentication > .It CheckHostIP > .It Cipher > @@ -768,6 +770,21 @@ Send log information using the > .Xr syslog 3 > system module. > By default this information is sent to stderr. > +.It Fl z Ar certificate_file > +Selects a file from which certificate information is loaded for public > +key authentication. For the certificate to be signed, the private key > +corresponding to > +.Ar certificate_file > +must also be provided for authentication, whether through > +.Xr ssh_agent 1 . > +or through an > +.Ar identity_file > +specified on the command line or in configuration files. > +Certificate files may also be specified on a per-host basis in > +the configuration file. It is possible to have multiple > +.Fl z > +options (and multiple certificates specified in > +configuration files). > .El > .Pp > .Nm > diff --git a/ssh.c b/ssh.c > index 3239108..e01790a 100644 > --- a/ssh.c > +++ b/ssh.c > @@ -207,7 +207,8 @@ usage(void) > " [-O ctl_cmd] [-o option] [-p port]\n" > " [-Q cipher | cipher-auth | mac | kex | key]\n" > " [-R address] [-S ctl_path] [-W host:port]\n" > -" [-w local_tun[:remote_tun]] [user@]hostname [command]\n" > +" [-w local_tun[:remote_tun]] [-z certificate_file]\n" > +" [user@]hostname [command]\n" > ); > exit(255); > } > @@ -215,6 +216,7 @@ usage(void) > static int ssh_session(void); > static int ssh_session2(void); > static void load_public_identity_files(void); > +static void load_certificate_files(void); > static void main_sigchld_handler(int); > > /* from muxclient.c */ > @@ -595,7 +597,7 @@ main(int ac, char **av) > > again: > while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx" > - "ACD:E:F:GI:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) { > + "ACD:E:F:GI:KL:MNO:PQ:R:S:TVw:W:XYyz:")) != -1) { > switch (opt) { > case '1': > options.protocol = SSH_PROTO_1; > @@ -906,6 +908,9 @@ main(int ac, char **av) > case 'F': > config = optarg; > break; > + case 'z': > + add_certificate_file(&options, NULL, optarg, 1); > + break; > default: > usage(); > } > @@ -1013,6 +1018,9 @@ main(int ac, char **av) > options.hostname = xstrdup(host); > } > > + /* If the user has specified certificate(s), load it now. */ > + load_certificate_files(); > + > /* If canonicalization requested then try to apply it */ > lowercase(host); > if (options.canonicalize_hostname != SSH_CANONICALISE_NO) > @@ -1353,6 +1361,13 @@ main(int ac, char **av) > } > } > > + for (i = 0; i < options.num_certificate_files; i++) { > + free(options.certificate_files[i]); > + options.certificate_files[i] = NULL; > + } > + > + > + > exit_status = compat20 ? ssh_session2() : ssh_session(); > packet_close(); > > @@ -1938,6 +1953,72 @@ ssh_session2(void) > options.escape_char : SSH_ESCAPECHAR_NONE, id); > } > > +/* Load certificate file(s) specified in options. */ > +static void > +load_certificate_files(void) > +{ > + char *filename, *cp, thishost[NI_MAXHOST]; > + char *pwdir = NULL, *pwname = NULL; > + struct passwd *pw; > + int i, n_ids; > + struct sshkey *cert; > + char *certificate_files[SSH_MAX_CERTIFICATE_FILES]; > + struct sshkey *certificates[SSH_MAX_CERTIFICATE_FILES]; > + > + n_ids = 0; > + memset(certificate_files, 0, sizeof(certificate_files)); > + memset(certificates, 0, sizeof(certificates)); > + > + if ((pw = getpwuid(original_real_uid)) == NULL) > + fatal("load_certificate_files: getpwuid failed"); > + pwname = xstrdup(pw->pw_name); > + pwdir = xstrdup(pw->pw_dir); > + if (gethostname(thishost, sizeof(thishost)) == -1) > + fatal("load_certificate_files: gethostname: %s", > + strerror(errno)); > + > + if (options.num_certificate_files > SSH_MAX_CERTIFICATE_FILES) > + fatal("load_certificate_files: too many certificates"); > + for (i = 0; i < options.num_certificate_files; i++) { > + cp = tilde_expand_filename(options.certificate_files[i], > + original_real_uid); > + filename = percent_expand(cp, "d", pwdir, > + "u", pwname, "l", thishost, "h", host, > + "r", options.user, (char *)NULL); > + free(cp); > + > + cert = key_load_public(filename, NULL); > + debug("certificate file %s type %d", filename, > + cert ? cert->type : -1); > + free(options.certificate_files[i]); > + if (cert == NULL) { > + free(filename); > + continue; > + } > + if (!key_is_cert(cert)) { > + debug("%s: key %s type %s is not a certificate", > + __func__, filename, key_type(cert)); > + key_free(cert); > + free(filename); > + continue; > + } > + > + certificate_files[n_ids] = filename; > + certificates[n_ids] = cert; > + ++n_ids; > + } > + options.num_certificate_files = n_ids; > + memcpy(options.certificate_files, certificate_files, sizeof(certificate_files)); > + memcpy(options.certificates, certificates, sizeof(certificates)); > + > + explicit_bzero(pwname, strlen(pwname)); > + free(pwname); > + explicit_bzero(pwdir, strlen(pwdir)); > + free(pwdir); > +} > + > + > + > static void > load_public_identity_files(void) > { > diff --git a/ssh.h b/ssh.h > index 4f8da5c..8fb7ba3 100644 > --- a/ssh.h > +++ b/ssh.h > @@ -19,6 +19,13 @@ > #define SSH_DEFAULT_PORT 22 > > /* > + * Maximum number of certificate files that can be specified > + * in configuration files or on the command line. > + */ > +#define SSH_MAX_CERTIFICATE_FILES 100 > + > + > +/* > * Maximum number of RSA authentication identity files that can be specified > * in configuration files or on the command line. > */ > diff --git a/ssh_config.5 b/ssh_config.5 > index e514398..17741b7 100644 > --- a/ssh_config.5 > +++ b/ssh_config.5 > @@ -325,6 +325,34 @@ to be canonicalized to names in the > or > .Dq *.c.example.com > domains. > +.It Cm CertificateFile > +Specifies a file from which the user's certificate is read. > +A corresponding private key must be provided separately in order > +to use this certificate. > +.Xr ssh 1 > +will attempt to use private keys provided as identity files > +or in the agent for such authentication. > +.Pp > +The file name may use the tilde > +syntax to refer to a user's home directory or one of the following > +escape characters: > +.Ql %d > +(local user's home directory), > +.Ql %u > +(local user name), > +.Ql %l > +(local host name), > +.Ql %h > +(remote host name) or > +.Ql %r > +(remote user name). > +.Pp > +It is possible to have multiple certificate files specified in > +configuration files; these certificates will be tried in sequence. > +Multiple > +.Cm CertificateFile > +directives will add to the list of certificates used for > +authentication. > .It Cm ChallengeResponseAuthentication > Specifies whether to use challenge-response authentication. > The argument to this keyword must be > @@ -911,6 +939,11 @@ differs from that of other configuration directives). > may be used in conjunction with > .Cm IdentitiesOnly > to select which identities in an agent are offered during authentication. > +.Cm IdentityFile > +may also be used in conjunction with > +.Cm CertificateFile > +in order to provide any certificate also needed for authentication with > +the identity. > .It Cm IgnoreUnknown > Specifies a pattern-list of unknown options to be ignored if they are > encountered in configuration parsing. > diff --git a/sshconnect2.c b/sshconnect2.c > index 34dbf9a..fb24b5e 100644 > --- a/sshconnect2.c > +++ b/sshconnect2.c > @@ -1016,6 +1016,7 @@ sign_and_send_pubkey(Authctxt *authctxt, Identity *id) > u_int skip = 0; > int ret = -1; > int have_sig = 1; > + int i; > char *fp; > > if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, > @@ -1053,6 +1054,33 @@ sign_and_send_pubkey(Authctxt *authctxt, Identity *id) > } > buffer_put_string(&b, blob, bloblen); > > + /* If the key is an input certificate, sign its private key instead. > + * If no such private key exists, return failure and continue with > + * other methods of authentication. > + * Else, just continue with the normal signing process. */ > + if (key_is_cert(id->key)) { > + for (i = 0; i < options.num_certificate_files; i++) { > + if (key_equal(id->key, options.certificates[i])) { > + Identity *id2; > + int matched = 0; > + TAILQ_FOREACH(id2, &authctxt->keys, next) { > + if (sshkey_equal_public(id->key, id2->key) && > + id->key->type != id2->key->type) { > + id = id2; > + matched = 1; > + break; > + } > + } > + if (!matched) { > + free(blob); > + buffer_free(&b); > + return 0; > + } > + break; > + } > + } > + } > + > /* generate signature */ > ret = identity_sign(id, &signature, &slen, > buffer_ptr(&b), buffer_len(&b), datafellows); > @@ -1189,9 +1217,11 @@ load_identity_file(char *filename, int userprovided) > > /* > * try keys in the following order: > - * 1. agent keys that are found in the config file > - * 2. other agent keys > - * 3. keys that are only listed in the config file > + * 1. certificates listed in the config file > + * 2. other input certificates > + * 3. agent keys that are found in the config file > + * 4. other agent keys > + * 5. keys that are only listed in the config file > */ > static void > pubkey_prepare(Authctxt *authctxt) > @@ -1245,6 +1275,17 @@ pubkey_prepare(Authctxt *authctxt) > free(id); > } > } > + /* list of certificates specified by user */ > + for (i = 0; i < options.num_certificate_files; i++) { > + key = options.certificates[i]; > + if (!key_is_cert(key)) > + continue; > + id = xcalloc(1, sizeof(*id)); > + id->key = key; > + id->filename = xstrdup(options.certificate_files[i]); > + id->userprovided = options.certificate_file_userprovided[i]; > + TAILQ_INSERT_TAIL(preferred, id, next); > + } > /* list of keys supported by the agent */ > if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { > if (r != SSH_ERR_AGENT_NOT_PRESENT) > -- > 1.9.1 > > _______________________________________________ > openssh-unix-dev mailing list > openssh-unix-dev@xxxxxxxxxxx > https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev > _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
