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|
/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#include <poll.h>
#include <signal.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/inotify.h>
#include <sys/signalfd.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <termios.h>
#include <unistd.h>
#include "alloc-util.h"
#include "ask-password-api.h"
#include "fd-util.h"
#include "fileio.h"
#include "format-util.h"
#include "io-util.h"
#include "log.h"
#include "macro.h"
#include "missing.h"
#include "mkdir.h"
#include "process-util.h"
#include "random-util.h"
#include "signal-util.h"
#include "socket-util.h"
#include "string-util.h"
#include "strv.h"
#include "terminal-util.h"
#include "time-util.h"
#include "umask-util.h"
#include "utf8.h"
#include "util.h"
#define KEYRING_TIMEOUT_USEC ((5 * USEC_PER_MINUTE) / 2)
static int lookup_key(const char *keyname, key_serial_t *ret) {
key_serial_t serial;
assert(keyname);
assert(ret);
serial = request_key("user", keyname, NULL, 0);
if (serial == -1)
return negative_errno();
*ret = serial;
return 0;
}
static int retrieve_key(key_serial_t serial, char ***ret) {
_cleanup_free_ char *p = NULL;
long m = 100, n;
char **l;
assert(ret);
for (;;) {
p = new(char, m);
if (!p)
return -ENOMEM;
n = keyctl(KEYCTL_READ, (unsigned long) serial, (unsigned long) p, (unsigned long) m, 0);
if (n < 0)
return -errno;
if (n < m)
break;
explicit_bzero(p, n);
free(p);
m *= 2;
}
l = strv_parse_nulstr(p, n);
if (!l)
return -ENOMEM;
explicit_bzero(p, n);
*ret = l;
return 0;
}
static int add_to_keyring(const char *keyname, AskPasswordFlags flags, char **passwords) {
_cleanup_strv_free_erase_ char **l = NULL;
_cleanup_free_ char *p = NULL;
key_serial_t serial;
size_t n;
int r;
assert(keyname);
assert(passwords);
if (!(flags & ASK_PASSWORD_PUSH_CACHE))
return 0;
r = lookup_key(keyname, &serial);
if (r >= 0) {
r = retrieve_key(serial, &l);
if (r < 0)
return r;
} else if (r != -ENOKEY)
return r;
r = strv_extend_strv(&l, passwords, true);
if (r <= 0)
return r;
r = strv_make_nulstr(l, &p, &n);
if (r < 0)
return r;
serial = add_key("user", keyname, p, n, KEY_SPEC_USER_KEYRING);
explicit_bzero(p, n);
if (serial == -1)
return -errno;
if (keyctl(KEYCTL_SET_TIMEOUT,
(unsigned long) serial,
(unsigned long) DIV_ROUND_UP(KEYRING_TIMEOUT_USEC, USEC_PER_SEC), 0, 0) < 0)
log_debug_errno(errno, "Failed to adjust timeout: %m");
log_debug("Added key to keyring as %" PRIi32 ".", serial);
return 1;
}
static int add_to_keyring_and_log(const char *keyname, AskPasswordFlags flags, char **passwords) {
int r;
assert(keyname);
assert(passwords);
r = add_to_keyring(keyname, flags, passwords);
if (r < 0)
return log_debug_errno(r, "Failed to add password to keyring: %m");
return 0;
}
int ask_password_keyring(const char *keyname, AskPasswordFlags flags, char ***ret) {
key_serial_t serial;
int r;
assert(keyname);
assert(ret);
if (!(flags & ASK_PASSWORD_ACCEPT_CACHED))
return -EUNATCH;
r = lookup_key(keyname, &serial);
if (r == -ENOSYS) /* when retrieving the distinction doesn't matter */
return -ENOKEY;
if (r < 0)
return r;
return retrieve_key(serial, ret);
}
static void backspace_chars(int ttyfd, size_t p) {
if (ttyfd < 0)
return;
while (p > 0) {
p--;
loop_write(ttyfd, "\b \b", 3, false);
}
}
static void backspace_string(int ttyfd, const char *str) {
size_t m;
assert(str);
if (ttyfd < 0)
return;
/* Backspaces through enough characters to entirely undo printing of the specified string. */
m = utf8_n_codepoints(str);
if (m == (size_t) -1)
m = strlen(str); /* Not a valid UTF-8 string? If so, let's backspace the number of bytes output. Most
* likely this happened because we are not in an UTF-8 locale, and in that case that
* is the correct thing to do. And even if it's not, terminals tend to stop
* backspacing at the leftmost column, hence backspacing too much should be mostly
* OK. */
backspace_chars(ttyfd, m);
}
int ask_password_tty(
int ttyfd,
const char *message,
const char *keyname,
usec_t until,
AskPasswordFlags flags,
const char *flag_file,
char **ret) {
enum {
POLL_TTY,
POLL_INOTIFY,
_POLL_MAX,
};
bool reset_tty = false, dirty = false, use_color = false;
_cleanup_close_ int cttyfd = -1, notify = -1;
struct termios old_termios, new_termios;
char passphrase[LINE_MAX + 1] = {}, *x;
struct pollfd pollfd[_POLL_MAX];
size_t p = 0, codepoint = 0;
int r;
assert(ret);
if (flags & ASK_PASSWORD_NO_TTY)
return -EUNATCH;
if (!message)
message = "Password:";
if (flag_file) {
notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
if (notify < 0)
return -errno;
if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0)
return -errno;
}
/* If the caller didn't specify a TTY, then use the controlling tty, if we can. */
if (ttyfd < 0)
ttyfd = cttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC);
if (ttyfd >= 0) {
if (tcgetattr(ttyfd, &old_termios) < 0)
return -errno;
if (flags & ASK_PASSWORD_CONSOLE_COLOR)
use_color = dev_console_colors_enabled();
else
use_color = colors_enabled();
if (use_color)
(void) loop_write(ttyfd, ANSI_HIGHLIGHT, STRLEN(ANSI_HIGHLIGHT), false);
(void) loop_write(ttyfd, message, strlen(message), false);
(void) loop_write(ttyfd, " ", 1, false);
if (use_color)
(void) loop_write(ttyfd, ANSI_NORMAL, STRLEN(ANSI_NORMAL), false);
new_termios = old_termios;
new_termios.c_lflag &= ~(ICANON|ECHO);
new_termios.c_cc[VMIN] = 1;
new_termios.c_cc[VTIME] = 0;
if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
r = -errno;
goto finish;
}
reset_tty = true;
}
pollfd[POLL_TTY] = (struct pollfd) {
.fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO,
.events = POLLIN,
};
pollfd[POLL_INOTIFY] = (struct pollfd) {
.fd = notify,
.events = POLLIN,
};
for (;;) {
int sleep_for = -1, k;
ssize_t n;
char c;
if (until > 0) {
usec_t y;
y = now(CLOCK_MONOTONIC);
if (y > until) {
r = -ETIME;
goto finish;
}
sleep_for = (int) DIV_ROUND_UP(until - y, USEC_PER_MSEC);
}
if (flag_file)
if (access(flag_file, F_OK) < 0) {
r = -errno;
goto finish;
}
k = poll(pollfd, notify >= 0 ? 2 : 1, sleep_for);
if (k < 0) {
if (errno == EINTR)
continue;
r = -errno;
goto finish;
} else if (k == 0) {
r = -ETIME;
goto finish;
}
if (notify >= 0 && pollfd[POLL_INOTIFY].revents != 0)
(void) flush_fd(notify);
if (pollfd[POLL_TTY].revents == 0)
continue;
n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1);
if (n < 0) {
if (IN_SET(errno, EINTR, EAGAIN))
continue;
r = -errno;
goto finish;
}
/* We treat EOF, newline and NUL byte all as valid end markers */
if (n == 0 || c == '\n' || c == 0)
break;
if (c == 21) { /* C-u */
if (!(flags & ASK_PASSWORD_SILENT))
backspace_string(ttyfd, passphrase);
explicit_bzero(passphrase, sizeof(passphrase));
p = codepoint = 0;
} else if (IN_SET(c, '\b', 127)) {
if (p > 0) {
size_t q;
if (!(flags & ASK_PASSWORD_SILENT))
backspace_chars(ttyfd, 1);
/* Remove a full UTF-8 codepoint from the end. For that, figure out where the last one
* begins */
q = 0;
for (;;) {
size_t z;
z = utf8_encoded_valid_unichar(passphrase + q);
if (z == 0) {
q = (size_t) -1; /* Invalid UTF8! */
break;
}
if (q + z >= p) /* This one brings us over the edge */
break;
q += z;
}
p = codepoint = q == (size_t) -1 ? p - 1 : q;
explicit_bzero(passphrase + p, sizeof(passphrase) - p);
} else if (!dirty && !(flags & ASK_PASSWORD_SILENT)) {
flags |= ASK_PASSWORD_SILENT;
/* There are two ways to enter silent mode. Either by pressing backspace as first key
* (and only as first key), or ... */
if (ttyfd >= 0)
(void) loop_write(ttyfd, "(no echo) ", 10, false);
} else if (ttyfd >= 0)
(void) loop_write(ttyfd, "\a", 1, false);
} else if (c == '\t' && !(flags & ASK_PASSWORD_SILENT)) {
backspace_string(ttyfd, passphrase);
flags |= ASK_PASSWORD_SILENT;
/* ... or by pressing TAB at any time. */
if (ttyfd >= 0)
(void) loop_write(ttyfd, "(no echo) ", 10, false);
} else if (p >= sizeof(passphrase)-1) {
/* Reached the size limit */
if (ttyfd >= 0)
(void) loop_write(ttyfd, "\a", 1, false);
} else {
passphrase[p++] = c;
if (!(flags & ASK_PASSWORD_SILENT) && ttyfd >= 0) {
/* Check if we got a complete UTF-8 character now. If so, let's output one '*'. */
n = utf8_encoded_valid_unichar(passphrase + codepoint);
if (n >= 0) {
codepoint = p;
(void) loop_write(ttyfd, (flags & ASK_PASSWORD_ECHO) ? &c : "*", 1, false);
}
}
dirty = true;
}
/* Let's forget this char, just to not keep needlessly copies of key material around */
c = 'x';
}
x = strndup(passphrase, p);
explicit_bzero(passphrase, sizeof(passphrase));
if (!x) {
r = -ENOMEM;
goto finish;
}
if (keyname)
(void) add_to_keyring_and_log(keyname, flags, STRV_MAKE(x));
*ret = x;
r = 0;
finish:
if (ttyfd >= 0 && reset_tty) {
(void) loop_write(ttyfd, "\n", 1, false);
(void) tcsetattr(ttyfd, TCSADRAIN, &old_termios);
}
return r;
}
static int create_socket(char **name) {
union sockaddr_union sa = {
.un.sun_family = AF_UNIX,
};
_cleanup_close_ int fd = -1;
static const int one = 1;
char *c;
int r;
assert(name);
fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (fd < 0)
return -errno;
snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%" PRIx64, random_u64());
RUN_WITH_UMASK(0177) {
if (bind(fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0)
return -errno;
}
if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0)
return -errno;
c = strdup(sa.un.sun_path);
if (!c)
return -ENOMEM;
*name = c;
r = fd;
fd = -1;
return r;
}
int ask_password_agent(
const char *message,
const char *icon,
const char *id,
const char *keyname,
usec_t until,
AskPasswordFlags flags,
char ***ret) {
enum {
FD_SOCKET,
FD_SIGNAL,
_FD_MAX
};
_cleanup_close_ int socket_fd = -1, signal_fd = -1, fd = -1;
char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
char final[sizeof(temp)] = "";
_cleanup_free_ char *socket_name = NULL;
_cleanup_strv_free_ char **l = NULL;
_cleanup_fclose_ FILE *f = NULL;
struct pollfd pollfd[_FD_MAX];
sigset_t mask, oldmask;
int r;
assert(ret);
if (flags & ASK_PASSWORD_NO_AGENT)
return -EUNATCH;
assert_se(sigemptyset(&mask) >= 0);
assert_se(sigset_add_many(&mask, SIGINT, SIGTERM, -1) >= 0);
assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) >= 0);
(void) mkdir_p_label("/run/systemd/ask-password", 0755);
fd = mkostemp_safe(temp);
if (fd < 0) {
r = fd;
goto finish;
}
(void) fchmod(fd, 0644);
f = fdopen(fd, "w");
if (!f) {
r = -errno;
goto finish;
}
fd = -1;
signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC);
if (signal_fd < 0) {
r = -errno;
goto finish;
}
socket_fd = create_socket(&socket_name);
if (socket_fd < 0) {
r = socket_fd;
goto finish;
}
fprintf(f,
"[Ask]\n"
"PID="PID_FMT"\n"
"Socket=%s\n"
"AcceptCached=%i\n"
"Echo=%i\n"
"NotAfter="USEC_FMT"\n",
getpid_cached(),
socket_name,
(flags & ASK_PASSWORD_ACCEPT_CACHED) ? 1 : 0,
(flags & ASK_PASSWORD_ECHO) ? 1 : 0,
until);
if (message)
fprintf(f, "Message=%s\n", message);
if (icon)
fprintf(f, "Icon=%s\n", icon);
if (id)
fprintf(f, "Id=%s\n", id);
r = fflush_and_check(f);
if (r < 0)
goto finish;
memcpy(final, temp, sizeof(temp));
final[sizeof(final)-11] = 'a';
final[sizeof(final)-10] = 's';
final[sizeof(final)-9] = 'k';
if (rename(temp, final) < 0) {
r = -errno;
goto finish;
}
zero(pollfd);
pollfd[FD_SOCKET].fd = socket_fd;
pollfd[FD_SOCKET].events = POLLIN;
pollfd[FD_SIGNAL].fd = signal_fd;
pollfd[FD_SIGNAL].events = POLLIN;
for (;;) {
char passphrase[LINE_MAX+1];
struct msghdr msghdr;
struct iovec iovec;
struct ucred *ucred;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
} control;
ssize_t n;
int k;
usec_t t;
t = now(CLOCK_MONOTONIC);
if (until > 0 && until <= t) {
r = -ETIME;
goto finish;
}
k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1);
if (k < 0) {
if (errno == EINTR)
continue;
r = -errno;
goto finish;
}
if (k <= 0) {
r = -ETIME;
goto finish;
}
if (pollfd[FD_SIGNAL].revents & POLLIN) {
r = -EINTR;
goto finish;
}
if (pollfd[FD_SOCKET].revents != POLLIN) {
r = -EIO;
goto finish;
}
zero(iovec);
iovec.iov_base = passphrase;
iovec.iov_len = sizeof(passphrase);
zero(control);
zero(msghdr);
msghdr.msg_iov = &iovec;
msghdr.msg_iovlen = 1;
msghdr.msg_control = &control;
msghdr.msg_controllen = sizeof(control);
n = recvmsg(socket_fd, &msghdr, 0);
if (n < 0) {
if (IN_SET(errno, EAGAIN, EINTR))
continue;
r = -errno;
goto finish;
}
cmsg_close_all(&msghdr);
if (n <= 0) {
log_debug("Message too short");
continue;
}
if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
control.cmsghdr.cmsg_level != SOL_SOCKET ||
control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
log_debug("Received message without credentials. Ignoring.");
continue;
}
ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
if (ucred->uid != 0) {
log_debug("Got request from unprivileged user. Ignoring.");
continue;
}
if (passphrase[0] == '+') {
/* An empty message refers to the empty password */
if (n == 1)
l = strv_new("", NULL);
else
l = strv_parse_nulstr(passphrase+1, n-1);
explicit_bzero(passphrase, n);
if (!l) {
r = -ENOMEM;
goto finish;
}
if (strv_isempty(l)) {
l = strv_free(l);
log_debug("Invalid packet");
continue;
}
break;
}
if (passphrase[0] == '-') {
r = -ECANCELED;
goto finish;
}
log_debug("Invalid packet");
}
if (keyname)
(void) add_to_keyring_and_log(keyname, flags, l);
*ret = TAKE_PTR(l);
r = 0;
finish:
if (socket_name)
(void) unlink(socket_name);
(void) unlink(temp);
if (final[0])
(void) unlink(final);
assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
return r;
}
int ask_password_auto(
const char *message,
const char *icon,
const char *id,
const char *keyname,
usec_t until,
AskPasswordFlags flags,
char ***ret) {
int r;
assert(ret);
if ((flags & ASK_PASSWORD_ACCEPT_CACHED) && keyname) {
r = ask_password_keyring(keyname, flags, ret);
if (r != -ENOKEY)
return r;
}
if (!(flags & ASK_PASSWORD_NO_TTY) && isatty(STDIN_FILENO)) {
char *s = NULL, **l = NULL;
r = ask_password_tty(-1, message, keyname, until, flags, NULL, &s);
if (r < 0)
return r;
r = strv_push(&l, s);
if (r < 0) {
string_erase(s);
free(s);
return -ENOMEM;
}
*ret = l;
return 0;
}
if (!(flags & ASK_PASSWORD_NO_AGENT))
return ask_password_agent(message, icon, id, keyname, until, flags, ret);
return -EUNATCH;
}
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