root/usr.bin/ssh/ssh-add.c
/* $OpenBSD: ssh-add.c,v 1.186 2026/03/05 05:44:15 djm Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Adds an identity to the authentication server, or removes an identity.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 *
 * SSH2 implementation,
 * Copyright (c) 2000, 2001 Markus Friedl.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

#include <sys/types.h>
#include <sys/stat.h>

#ifdef WITH_OPENSSL
#include <openssl/evp.h>
#endif

#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <time.h>

#include "xmalloc.h"
#include "ssh.h"
#include "log.h"
#include "sshkey.h"
#include "sshbuf.h"
#include "authfd.h"
#include "authfile.h"
#include "pathnames.h"
#include "misc.h"
#include "ssherr.h"
#include "digest.h"
#include "ssh-sk.h"
#include "sk-api.h"
#include "hostfile.h"

#define CERT_EXPIRY_GRACE       (5*60)

/* argv0 */
extern char *__progname;

/* Default files to add */
static char *default_files[] = {
        _PATH_SSH_CLIENT_ID_RSA,
        _PATH_SSH_CLIENT_ID_ECDSA,
        _PATH_SSH_CLIENT_ID_ECDSA_SK,
        _PATH_SSH_CLIENT_ID_ED25519,
        _PATH_SSH_CLIENT_ID_ED25519_SK,
        NULL
};

static int fingerprint_hash = SSH_FP_HASH_DEFAULT;

/* Default lifetime (0 == forever) */
static int lifetime = 0;

/* User has to confirm key use */
static int confirm = 0;

/* we keep a cache of one passphrase */
static char *pass = NULL;
static void
clear_pass(void)
{
        if (pass) {
                freezero(pass, strlen(pass));
                pass = NULL;
        }
}

static int
delete_one(int agent_fd, const struct sshkey *key, const char *comment,
    const char *path, int qflag)
{
        int r;

        if ((r = ssh_remove_identity(agent_fd, key)) != 0) {
                fprintf(stderr, "Could not remove identity \"%s\": %s\n",
                    path, ssh_err(r));
                return r;
        }
        if (!qflag) {
                fprintf(stderr, "Identity removed: %s %s (%s)\n", path,
                    sshkey_type(key), comment ? comment : "no comment");
        }
        return 0;
}

static int
delete_stdin(int agent_fd, int qflag, int key_only, int cert_only)
{
        char *line = NULL, *cp;
        size_t linesize = 0;
        struct sshkey *key = NULL;
        int lnum = 0, r, ret = -1;

        while (getline(&line, &linesize, stdin) != -1) {
                lnum++;
                sshkey_free(key);
                key = NULL;
                line[strcspn(line, "\n")] = '\0';
                cp = line + strspn(line, " \t");
                if (*cp == '#' || *cp == '\0')
                        continue;
                if ((key = sshkey_new(KEY_UNSPEC)) == NULL)
                        fatal_f("sshkey_new");
                if ((r = sshkey_read(key, &cp)) != 0) {
                        error_r(r, "(stdin):%d: invalid key", lnum);
                        continue;
                }
                if ((!key_only && !cert_only) ||
                    (key_only && !sshkey_is_cert(key)) ||
                    (cert_only && sshkey_is_cert(key))) {
                        if (delete_one(agent_fd, key, cp,
                            "(stdin)", qflag) == 0)
                                ret = 0;
                }
        }
        sshkey_free(key);
        free(line);
        return ret;
}

static int
delete_file(int agent_fd, const char *filename, int key_only,
    int cert_only, int qflag)
{
        struct sshkey *public, *cert = NULL;
        char *certpath = NULL, *comment = NULL;
        int r, ret = -1;

        if (strcmp(filename, "-") == 0)
                return delete_stdin(agent_fd, qflag, key_only, cert_only);

        if ((r = sshkey_load_public(filename, &public,  &comment)) != 0) {
                printf("Bad key file %s: %s\n", filename, ssh_err(r));
                return -1;
        }
        if ((!key_only && !cert_only) ||
            (key_only && !sshkey_is_cert(public)) ||
            (cert_only && sshkey_is_cert(public))) {
                if (delete_one(agent_fd, public, comment, filename, qflag) == 0)
                        ret = 0;
        }

        if (key_only)
                goto out;

        /* Now try to delete the corresponding certificate too */
        free(comment);
        comment = NULL;
        xasprintf(&certpath, "%s-cert.pub", filename);
        if ((r = sshkey_load_public(certpath, &cert, &comment)) != 0) {
                if (r != SSH_ERR_SYSTEM_ERROR || errno != ENOENT)
                        error_r(r, "Failed to load certificate \"%s\"", certpath);
                goto out;
        }

        if (!sshkey_equal_public(cert, public))
                fatal("Certificate %s does not match private key %s",
                    certpath, filename);

        if (delete_one(agent_fd, cert, comment, certpath, qflag) == 0)
                ret = 0;

 out:
        sshkey_free(cert);
        sshkey_free(public);
        free(certpath);
        free(comment);

        return ret;
}

/* Send a request to remove all identities. */
static int
delete_all(int agent_fd, int qflag)
{
        int ret = -1;

        /*
         * Since the agent might be forwarded, old or non-OpenSSH, when asked
         * to remove all keys, attempt to remove both protocol v.1 and v.2
         * keys.
         */
        if (ssh_remove_all_identities(agent_fd, 2) == 0)
                ret = 0;
        /* ignore error-code for ssh1 */
        ssh_remove_all_identities(agent_fd, 1);

        if (ret != 0)
                fprintf(stderr, "Failed to remove all identities.\n");
        else if (!qflag)
                fprintf(stderr, "All identities removed.\n");

        return ret;
}

static int
query_exts(int agent_fd)
{
        int r;
        char **exts = NULL;
        size_t i;

        if ((r = ssh_agent_query_extensions(agent_fd, &exts)) != 0)
                fatal_r(r, "unable to query supported extensions");
        for (i = 0; exts != NULL && exts[i] != NULL; i++)
                puts(exts[i]);
        stringlist_free(exts);
        return 0;
}

static int
check_cert_lifetime(const struct sshkey *cert, int cert_lifetime)
{
        time_t now;
        uint64_t n;

        if (cert == NULL || cert->cert == NULL || !sshkey_is_cert(cert) ||
            cert->cert->valid_before == 0xFFFFFFFFFFFFFFFFULL)
                return cert_lifetime;
        if ((now = time(NULL)) <= 0)
                fatal_f("system time is at/before epoch");
        if ((uint64_t)now > (cert->cert->valid_before + CERT_EXPIRY_GRACE))
                return -1; /* certificate already expired */
        n = (CERT_EXPIRY_GRACE + cert->cert->valid_before) - (uint64_t)now;
        n = MINIMUM(n, INT_MAX);
        if (cert_lifetime <= 0)
                return (int)n;
        return MINIMUM(cert_lifetime, (int)n);
}

static int
add_file(int agent_fd, const char *filename, int key_only, int cert_only,
    int qflag, int Nflag, const char *skprovider,
    struct dest_constraint **dest_constraints,
    size_t ndest_constraints)
{
        struct sshkey *private = NULL, *cert = NULL;
        char *comment = NULL;
        char msg[1024], *certpath = NULL;
        int cert_lifetime, r, fd, ret = -1;
        struct sshbuf *keyblob;

        if (strcmp(filename, "-") == 0) {
                fd = STDIN_FILENO;
                filename = "(stdin)";
        } else if ((fd = open(filename, O_RDONLY)) == -1) {
                perror(filename);
                return -1;
        }

        /*
         * Since we'll try to load a keyfile multiple times, permission errors
         * will occur multiple times, so check perms first and bail if wrong.
         */
        if (fd != STDIN_FILENO) {
                if (sshkey_perm_ok(fd, filename) != 0) {
                        close(fd);
                        return -1;
                }
        }
        if ((r = sshbuf_load_fd(fd, &keyblob)) != 0) {
                fprintf(stderr, "Error loading key \"%s\": %s\n",
                    filename, ssh_err(r));
                sshbuf_free(keyblob);
                close(fd);
                return -1;
        }
        close(fd);

        /* At first, try empty passphrase */
        if ((r = sshkey_parse_private_fileblob(keyblob, "", &private,
            &comment)) != 0 && r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
                fprintf(stderr, "Error loading key \"%s\": %s\n",
                    filename, ssh_err(r));
                goto fail_load;
        }
        /* try last */
        if (private == NULL && pass != NULL) {
                if ((r = sshkey_parse_private_fileblob(keyblob, pass, &private,
                    &comment)) != 0 && r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
                        fprintf(stderr, "Error loading key \"%s\": %s\n",
                            filename, ssh_err(r));
                        goto fail_load;
                }
        }
        if (private == NULL) {
                /* clear passphrase since it did not work */
                clear_pass();
                snprintf(msg, sizeof msg, "Enter passphrase for %s%s: ",
                    filename, confirm ? " (will confirm each use)" : "");
                for (;;) {
                        pass = read_passphrase(msg, RP_ALLOW_STDIN);
                        if (strcmp(pass, "") == 0)
                                goto fail_load;
                        if ((r = sshkey_parse_private_fileblob(keyblob, pass,
                            &private, &comment)) == 0)
                                break;
                        else if (r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
                                fprintf(stderr,
                                    "Error loading key \"%s\": %s\n",
                                    filename, ssh_err(r));
 fail_load:
                                clear_pass();
                                sshbuf_free(keyblob);
                                return -1;
                        }
                        clear_pass();
                        snprintf(msg, sizeof msg,
                            "Bad passphrase, try again for %s%s: ", filename,
                            confirm ? " (will confirm each use)" : "");
                }
        }
        if (comment == NULL || *comment == '\0')
                comment = xstrdup(filename);
        sshbuf_free(keyblob);

        if (sshkey_is_sk(private)) {
                if (skprovider == NULL) {
                        fprintf(stderr, "Cannot load FIDO key %s "
                            "without provider\n", filename);
                        goto out;
                }
        } else {
                /* Don't send provider constraint for other keys */
                skprovider = NULL;
        }

        if (!cert_only) {
                if ((r = ssh_add_identity_constrained(agent_fd, private,
                    comment, lifetime, confirm, skprovider,
                    dest_constraints, ndest_constraints)) == 0) {
                        ret = 0;
                        if (!qflag) {
                                fprintf(stderr, "Identity added: %s (%s)\n",
                                    filename, comment);
                                if (lifetime != 0) {
                                        fprintf(stderr, "Lifetime set to %s\n",
                                            fmt_timeframe((time_t)lifetime));
                                }
                                if (confirm != 0) {
                                        fprintf(stderr, "The user must confirm "
                                            "each use of the key\n");
                                }
                        }
                } else {
                        fprintf(stderr, "Could not add identity \"%s\": %s\n",
                            filename, ssh_err(r));
                }
        }

        /* Skip trying to load the cert if requested */
        if (key_only)
                goto out;

        /* Now try to add the certificate flavour too */
        xasprintf(&certpath, "%s-cert.pub", filename);
        if ((r = sshkey_load_public(certpath, &cert, NULL)) != 0) {
                if (r != SSH_ERR_SYSTEM_ERROR || errno != ENOENT)
                        error_r(r, "Failed to load certificate \"%s\"",
                            certpath);
                goto out;
        }

        if (!sshkey_equal_public(cert, private)) {
                error("Certificate %s does not match private key %s",
                    certpath, filename);
                goto out;
        }

        cert_lifetime = lifetime;
        if (!Nflag &&
            (cert_lifetime = check_cert_lifetime(cert, cert_lifetime)) == -1) {
                logit("Certificate %s has already expired; ignored", certpath);
                goto out;
        }

        /* Graft with private bits */
        if ((r = sshkey_to_certified(private)) != 0) {
                error_fr(r, "sshkey_to_certified");
                goto out;
        }
        if ((r = sshkey_cert_copy(cert, private)) != 0) {
                error_fr(r, "sshkey_cert_copy");
                goto out;
        }
        /* send to agent */
        if ((r = ssh_add_identity_constrained(agent_fd, private, comment,
            cert_lifetime, confirm, skprovider,
            dest_constraints, ndest_constraints)) != 0) {
                error_r(r, "Certificate %s (%s) add failed", certpath,
                    private->cert->key_id);
                goto out;
        }
        /* success */
        if (!qflag) {
                fprintf(stderr, "Certificate added: %s (%s)\n", certpath,
                    private->cert->key_id);
                if (cert_lifetime != 0) {
                        fprintf(stderr, "Lifetime set to %s\n",
                            fmt_timeframe((time_t)cert_lifetime));
                }
                if (confirm != 0) {
                        fprintf(stderr, "The user must confirm each use "
                            "of the key\n");
                }
        }

 out:
        free(certpath);
        free(comment);
        sshkey_free(cert);
        sshkey_free(private);

        return ret;
}

static int
update_card(int agent_fd, int add, const char *id, int qflag,
    int key_only, int cert_only,
    struct dest_constraint **dest_constraints, size_t ndest_constraints,
    struct sshkey **certs, size_t ncerts)
{
        char *pin = NULL;
        int r, ret = -1;

        if (key_only)
                ncerts = 0;

        if (add) {
                if ((pin = read_passphrase("Enter passphrase for PKCS#11: ",
                    RP_ALLOW_STDIN)) == NULL)
                        return -1;
        }

        if ((r = ssh_update_card(agent_fd, add, id, pin == NULL ? "" : pin,
            lifetime, confirm, dest_constraints, ndest_constraints,
            cert_only, certs, ncerts)) == 0) {
                ret = 0;
                if (!qflag) {
                        fprintf(stderr, "Card %s: %s\n",
                            add ? "added" : "removed", id);
                }
        } else {
                fprintf(stderr, "Could not %s card \"%s\": %s\n",
                    add ? "add" : "remove", id, ssh_err(r));
                ret = -1;
        }
        free(pin);
        return ret;
}

static int
test_key(int agent_fd, const char *filename)
{
        struct sshkey *key = NULL;
        u_char *sig = NULL;
        const char *alg = NULL;
        size_t slen = 0;
        int r, ret = -1;
        char data[1024];

        if ((r = sshkey_load_public(filename, &key, NULL)) != 0) {
                error_r(r, "Couldn't read public key %s", filename);
                return -1;
        }
        if (sshkey_type_plain(key->type) == KEY_RSA)
                alg = "rsa-sha2-256";
        arc4random_buf(data, sizeof(data));
        if ((r = ssh_agent_sign(agent_fd, key, &sig, &slen, data, sizeof(data),
            alg, 0)) != 0) {
                error_r(r, "Agent signature failed for %s", filename);
                goto done;
        }
        if ((r = sshkey_verify(key, sig, slen, data, sizeof(data),
            alg, 0, NULL)) != 0) {
                error_r(r, "Signature verification failed for %s", filename);
                goto done;
        }
        /* success */
        ret = 0;
 done:
        free(sig);
        sshkey_free(key);
        return ret;
}

static int
list_identities(int agent_fd, int do_fp)
{
        char *fp;
        int r;
        struct ssh_identitylist *idlist;
        size_t i;

        if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
                if (r != SSH_ERR_AGENT_NO_IDENTITIES)
                        fprintf(stderr, "error fetching identities: %s\n",
                            ssh_err(r));
                else
                        printf("The agent has no identities.\n");
                return -1;
        }
        for (i = 0; i < idlist->nkeys; i++) {
                if (do_fp) {
                        fp = sshkey_fingerprint(idlist->keys[i],
                            fingerprint_hash, SSH_FP_DEFAULT);
                        printf("%u %s %s (%s)\n", sshkey_size(idlist->keys[i]),
                            fp == NULL ? "(null)" : fp, idlist->comments[i],
                            sshkey_type(idlist->keys[i]));
                        free(fp);
                } else {
                        if ((r = sshkey_write(idlist->keys[i], stdout)) != 0) {
                                fprintf(stderr, "sshkey_write: %s\n",
                                    ssh_err(r));
                                continue;
                        }
                        fprintf(stdout, " %s\n", idlist->comments[i]);
                }
        }
        ssh_free_identitylist(idlist);
        return 0;
}

static int
lock_agent(int agent_fd, int lock)
{
        char prompt[100], *p1, *p2;
        int r, passok = 1, ret = -1;

        strlcpy(prompt, "Enter lock password: ", sizeof(prompt));
        p1 = read_passphrase(prompt, RP_ALLOW_STDIN);
        if (lock) {
                strlcpy(prompt, "Again: ", sizeof prompt);
                p2 = read_passphrase(prompt, RP_ALLOW_STDIN);
                if (strcmp(p1, p2) != 0) {
                        fprintf(stderr, "Passwords do not match.\n");
                        passok = 0;
                }
                freezero(p2, strlen(p2));
        }
        if (passok) {
                if ((r = ssh_lock_agent(agent_fd, lock, p1)) == 0) {
                        fprintf(stderr, "Agent %slocked.\n", lock ? "" : "un");
                        ret = 0;
                } else {
                        fprintf(stderr, "Failed to %slock agent: %s\n",
                            lock ? "" : "un", ssh_err(r));
                }
        }
        freezero(p1, strlen(p1));
        return (ret);
}

static int
load_resident_keys(int agent_fd, const char *skprovider, int qflag,
    struct dest_constraint **dest_constraints, size_t ndest_constraints)
{
        struct sshsk_resident_key **srks;
        size_t nsrks, i;
        struct sshkey *key;
        int r, ok = 0;
        char *fp;

        pass = read_passphrase("Enter PIN for authenticator: ", RP_ALLOW_STDIN);
        if ((r = sshsk_load_resident(skprovider, NULL, pass, 0,
            &srks, &nsrks)) != 0) {
                error_r(r, "Unable to load resident keys");
                return r;
        }
        for (i = 0; i < nsrks; i++) {
                key = srks[i]->key;
                if ((fp = sshkey_fingerprint(key,
                    fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
                        fatal_f("sshkey_fingerprint failed");
                if ((r = ssh_add_identity_constrained(agent_fd, key,
                    key->sk_application, lifetime, confirm, skprovider,
                    dest_constraints, ndest_constraints)) != 0) {
                        error("Unable to add key %s %s",
                            sshkey_type(key), fp);
                        free(fp);
                        ok = r;
                        continue;
                }
                if (ok == 0)
                        ok = 1;
                if (!qflag) {
                        fprintf(stderr, "Resident identity added: %s %s\n",
                            sshkey_type(key), fp);
                        if (lifetime != 0) {
                                fprintf(stderr,
                                    "Lifetime set to %d seconds\n", lifetime);
                        }
                        if (confirm != 0) {
                                fprintf(stderr, "The user must confirm "
                                    "each use of the key\n");
                        }
                }
                free(fp);
        }
        sshsk_free_resident_keys(srks, nsrks);
        if (nsrks == 0)
                return SSH_ERR_KEY_NOT_FOUND;
        return ok == 1 ? 0 : ok;
}

static int
do_file(int agent_fd, int deleting, int key_only, int cert_only,
    char *file, int qflag, int Nflag, const char *skprovider,
    struct dest_constraint **dest_constraints, size_t ndest_constraints)
{
        if (deleting) {
                if (delete_file(agent_fd, file, key_only,
                    cert_only, qflag) == -1)
                        return -1;
        } else {
                if (add_file(agent_fd, file, key_only, cert_only, qflag, Nflag,
                    skprovider, dest_constraints, ndest_constraints) == -1)
                        return -1;
        }
        return 0;
}

static void
free_dest_constraint_hop(struct dest_constraint_hop *dch)
{
        u_int i;

        if (dch == NULL)
                return;
        free(dch->user);
        free(dch->hostname);
        for (i = 0; i < dch->nkeys; i++)
                sshkey_free(dch->keys[i]);
        free(dch->keys);
        free(dch->key_is_ca);
}

static void
free_dest_constraints(struct dest_constraint **dcs, size_t ndcs)
{
        size_t i;

        for (i = 0; i < ndcs; i++) {
                free_dest_constraint_hop(&dcs[i]->from);
                free_dest_constraint_hop(&dcs[i]->to);
                free(dcs[i]);
        }
        free(dcs);
}


static void
parse_dest_constraint_hop(const char *s, struct dest_constraint_hop *dch,
    char **hostkey_files)
{
        char *user = NULL, *host, *os, *path;
        size_t i;
        struct hostkeys *hostkeys;
        const struct hostkey_entry *hke;
        int r, want_ca;

        memset(dch, '\0', sizeof(*dch));
        os = xstrdup(s);
        if ((host = strrchr(os, '@')) == NULL)
                host = os;
        else {
                *host++ = '\0';
                user = os;
        }
        cleanhostname(host);
        /* Trivial case: username@ (all hosts) */
        if (*host == '\0') {
                if (user == NULL) {
                        fatal("Invalid key destination constraint \"%s\": "
                            "does not specify user or host", s);
                }
                dch->user = xstrdup(user);
                /* other fields left blank */
                free(os);
                return;
        }
        if (hostkey_files == NULL)
                fatal_f("no hostkey files");
        /* Otherwise we need to look up the keys for this hostname */
        hostkeys = init_hostkeys();
        for (i = 0; hostkey_files[i]; i++) {
                path = tilde_expand_filename(hostkey_files[i], getuid());
                debug2_f("looking up host keys for \"%s\" in %s", host, path);
                load_hostkeys(hostkeys, host, path, 0);
                free(path);
        }
        dch->user = user == NULL ? NULL : xstrdup(user);
        dch->hostname = xstrdup(host);
        for (i = 0; i < hostkeys->num_entries; i++) {
                hke = hostkeys->entries + i;
                want_ca = hke->marker == MRK_CA;
                if (hke->marker != MRK_NONE && !want_ca)
                        continue;
                debug3_f("%s%s%s: adding %s %skey from %s:%lu as key %u",
                    user == NULL ? "": user, user == NULL ? "" : "@",
                    host, sshkey_type(hke->key), want_ca ? "CA " : "",
                    hke->file, hke->line, dch->nkeys);
                dch->keys = xrecallocarray(dch->keys, dch->nkeys,
                    dch->nkeys + 1, sizeof(*dch->keys));
                dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys,
                    dch->nkeys + 1, sizeof(*dch->key_is_ca));
                if ((r = sshkey_from_private(hke->key,
                    &(dch->keys[dch->nkeys]))) != 0)
                        fatal_fr(r, "sshkey_from_private");
                dch->key_is_ca[dch->nkeys] = want_ca;
                dch->nkeys++;
        }
        if (dch->nkeys == 0)
                fatal("No host keys found for destination \"%s\"", host);
        free_hostkeys(hostkeys);
        free(os);
        return;
}

static void
parse_dest_constraint(const char *s, struct dest_constraint ***dcp,
    size_t *ndcp, char **hostkey_files)
{
        struct dest_constraint *dc;
        char *os, *cp;

        dc = xcalloc(1, sizeof(*dc));
        os = xstrdup(s);
        if ((cp = strchr(os, '>')) == NULL) {
                /* initial hop; no 'from' hop specified */
                parse_dest_constraint_hop(os, &dc->to, hostkey_files);
        } else {
                /* two hops specified */
                *(cp++) = '\0';
                parse_dest_constraint_hop(os, &dc->from, hostkey_files);
                parse_dest_constraint_hop(cp, &dc->to, hostkey_files);
                if (dc->from.user != NULL) {
                        fatal("Invalid key constraint %s: cannot specify "
                            "user on 'from' host", os);
                }
        }
        /* XXX eliminate or error on duplicates */
        debug2_f("constraint %zu: %s%s%s (%u keys) > %s%s%s (%u keys)", *ndcp,
            dc->from.user ? dc->from.user : "", dc->from.user ? "@" : "",
            dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys,
            dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "",
            dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys);
        *dcp = xrecallocarray(*dcp, *ndcp, *ndcp + 1, sizeof(**dcp));
        (*dcp)[(*ndcp)++] = dc;
        free(os);
}


static void
usage(void)
{
        fprintf(stderr,
"usage: ssh-add [-CcDdKkLlqvXx] [-E fingerprint_hash] [-H hostkey_file]\n"
"               [-h destination_constraint] [-S provider] [-t life]\n"
"               [file ...]\n"
"       ssh-add -s pkcs11 [-Cv] [certificate ...]\n"
"       ssh-add -e pkcs11\n"
"       ssh-add -T pubkey ...\n"
        );
}

int
main(int argc, char **argv)
{
        extern char *optarg;
        extern int optind;
        int agent_fd;
        char *pkcs11provider = NULL, *skprovider = NULL;
        char **dest_constraint_strings = NULL, **hostkey_files = NULL;
        int r, i, ch, deleting = 0, ret = 0, key_only = 0, cert_only = 0;
        int do_download = 0, xflag = 0, lflag = 0, Dflag = 0;
        int Qflag = 0, qflag = 0, Tflag = 0, Nflag = 0;
        SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
        LogLevel log_level = SYSLOG_LEVEL_INFO;
        struct sshkey *k, **certs = NULL;
        struct dest_constraint **dest_constraints = NULL;
        size_t n, ndest_constraints = 0, ncerts = 0;

        /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
        sanitise_stdfd();

        log_init(__progname, log_level, log_facility, 1);

        setvbuf(stdout, NULL, _IOLBF, 0);

        /* First, get a connection to the authentication agent. */
        switch (r = ssh_get_authentication_socket(&agent_fd)) {
        case 0:
                break;
        case SSH_ERR_AGENT_NOT_PRESENT:
                fprintf(stderr, "Could not open a connection to your "
                    "authentication agent.\n");
                exit(2);
        default:
                fprintf(stderr, "Error connecting to agent: %s\n", ssh_err(r));
                exit(2);
        }

        skprovider = getenv("SSH_SK_PROVIDER");

        while ((ch = getopt(argc, argv, "vkKlLNCcdDTxXE:e:h:H:M:m:Qqs:S:t:")) != -1) {
                switch (ch) {
                case 'v':
                        if (log_level == SYSLOG_LEVEL_INFO)
                                log_level = SYSLOG_LEVEL_DEBUG1;
                        else if (log_level < SYSLOG_LEVEL_DEBUG3)
                                log_level++;
                        break;
                case 'N':
                        Nflag = 1;
                        break;
                case 'E':
                        fingerprint_hash = ssh_digest_alg_by_name(optarg);
                        if (fingerprint_hash == -1)
                                fatal("Invalid hash algorithm \"%s\"", optarg);
                        break;
                case 'H':
                        stringlist_append(&hostkey_files, optarg);
                        break;
                case 'h':
                        stringlist_append(&dest_constraint_strings, optarg);
                        break;
                case 'k':
                        key_only = 1;
                        break;
                case 'C':
                        cert_only = 1;
                        break;
                case 'K':
                        do_download = 1;
                        break;
                case 'l':
                case 'L':
                        if (lflag != 0)
                                fatal("-%c flag already specified", lflag);
                        lflag = ch;
                        break;
                case 'x':
                case 'X':
                        if (xflag != 0)
                                fatal("-%c flag already specified", xflag);
                        xflag = ch;
                        break;
                case 'c':
                        confirm = 1;
                        break;
                case 'm':
                case 'M':
                        /* deprecated */
                        break;
                case 'd':
                        deleting = 1;
                        break;
                case 'D':
                        Dflag = 1;
                        break;
                case 's':
                        pkcs11provider = optarg;
                        break;
                case 'S':
                        skprovider = optarg;
                        break;
                case 'e':
                        deleting = 1;
                        pkcs11provider = optarg;
                        break;
                case 't':
                        if ((lifetime = convtime(optarg)) == -1 ||
                            lifetime < 0 || (u_long)lifetime > UINT32_MAX) {
                                fprintf(stderr, "Invalid lifetime\n");
                                ret = 1;
                                goto done;
                        }
                        break;
                case 'q':
                        qflag = 1;
                        break;
                case 'Q':
                        Qflag = 1;
                        break;
                case 'T':
                        Tflag = 1;
                        break;
                default:
                        usage();
                        ret = 1;
                        goto done;
                }
        }
        log_init(__progname, log_level, log_facility, 1);

        if ((xflag != 0) + (lflag != 0) + (Dflag != 0) + (Qflag != 0) > 1)
                fatal("Invalid combination of actions");
        else if (xflag) {
                if (lock_agent(agent_fd, xflag == 'x' ? 1 : 0) == -1)
                        ret = 1;
                goto done;
        } else if (lflag) {
                if (list_identities(agent_fd, lflag == 'l' ? 1 : 0) == -1)
                        ret = 1;
                goto done;
        } else if (Dflag) {
                if (delete_all(agent_fd, qflag) == -1)
                        ret = 1;
                goto done;
        } else if (Qflag) {
                if (query_exts(agent_fd) == -1)
                        ret = 1;
                goto done;
        }

        if (skprovider == NULL)
                skprovider = "internal";
        if (hostkey_files == NULL) {
                /* use defaults from readconf.c */
                stringlist_append(&hostkey_files, _PATH_SSH_USER_HOSTFILE);
                stringlist_append(&hostkey_files, _PATH_SSH_USER_HOSTFILE2);
                stringlist_append(&hostkey_files, _PATH_SSH_SYSTEM_HOSTFILE);
                stringlist_append(&hostkey_files, _PATH_SSH_SYSTEM_HOSTFILE2);
        }
        if (dest_constraint_strings != NULL) {
                for (i = 0; dest_constraint_strings[i] != NULL; i++) {
                        parse_dest_constraint(dest_constraint_strings[i],
                          &dest_constraints, &ndest_constraints, hostkey_files);
                }
        }

        argc -= optind;
        argv += optind;
        if (Tflag) {
                if (argc <= 0)
                        fatal("no keys to test");
                for (r = i = 0; i < argc; i++)
                        r |= test_key(agent_fd, argv[i]);
                ret = r == 0 ? 0 : 1;
                goto done;
        }
        if (pkcs11provider != NULL) {
                for (i = 0; i < argc; i++) {
                        if ((r = sshkey_load_public(argv[i], &k, NULL)) != 0)
                                fatal_fr(r, "load certificate %s", argv[i]);
                        certs = xrecallocarray(certs, ncerts, ncerts + 1,
                            sizeof(*certs));
                        debug2("%s: %s", argv[i], sshkey_ssh_name(k));
                        certs[ncerts++] = k;
                }
                debug2_f("loaded %zu certificates", ncerts);
                if (update_card(agent_fd, !deleting, pkcs11provider,
                    qflag, key_only, cert_only,
                    dest_constraints, ndest_constraints,
                    certs, ncerts) == -1)
                        ret = 1;
                for (n = 0; n < ncerts; n++)
                        sshkey_free(certs[n]);
                free(certs);
                goto done;
        }
        if (do_download) {
                if (skprovider == NULL)
                        fatal("Cannot download keys without provider");
                if (load_resident_keys(agent_fd, skprovider, qflag,
                    dest_constraints, ndest_constraints) != 0)
                        ret = 1;
                goto done;
        }
        if (argc == 0) {
                char buf[PATH_MAX];
                struct passwd *pw;
                struct stat st;
                int count = 0;

                if ((pw = getpwuid(getuid())) == NULL) {
                        fprintf(stderr, "No user found with uid %u\n",
                            (u_int)getuid());
                        ret = 1;
                        goto done;
                }

                for (i = 0; default_files[i]; i++) {
                        snprintf(buf, sizeof(buf), "%s/%s", pw->pw_dir,
                            default_files[i]);
                        if (stat(buf, &st) == -1)
                                continue;
                        if (do_file(agent_fd, deleting, key_only, cert_only,
                            buf, qflag, Nflag, skprovider,
                            dest_constraints, ndest_constraints) == -1)
                                ret = 1;
                        else
                                count++;
                }
                if (count == 0)
                        ret = 1;
        } else {
                for (i = 0; i < argc; i++) {
                        if (do_file(agent_fd, deleting, key_only, cert_only,
                            argv[i], qflag, Nflag, skprovider,
                            dest_constraints, ndest_constraints) == -1)
                                ret = 1;
                }
        }
done:
        clear_pass();
        stringlist_free(hostkey_files);
        stringlist_free(dest_constraint_strings);
        free_dest_constraints(dest_constraints, ndest_constraints);
        ssh_close_authentication_socket(agent_fd);
        return ret;
}