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systemd/src/shared/ask-password-api.c
Zbigniew Jędrzejewski-Szmek b92bea5d2a Use initalization instead of explicit zeroing 
Before, we would initialize many fields twice: first
by filling the structure with zeros, and then a second
time with the real values. We can let the compiler do
the job for us, avoiding one copy.

A downside of this patch is that text gets slightly
bigger. This is because all zero() calls are effectively
inlined:

$ size build/.libs/systemd
         text    data     bss     dec     hex filename
before 897737  107300    2560 1007597   f5fed build/.libs/systemd
after  897873  107300    2560 1007733   f6075 build/.libs/systemd

… actually less than 1‰.

A few asserts that the parameter is not null had to be removed. I
don't think this changes much, because first, it is quite unlikely
for the assert to fail, and second, an immediate SEGV is almost as
good as an assert.
2013-04-05 19:50:57 -04:00

576 lines
16 KiB
C
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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
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 <stdbool.h>
#include <termios.h>
#include <unistd.h>
#include <sys/poll.h>
#include <sys/inotify.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <string.h>
#include <sys/un.h>
#include <stddef.h>
#include <sys/signalfd.h>
#include "util.h"
#include "mkdir.h"
#include "strv.h"
#include "ask-password-api.h"
static void backspace_chars(int ttyfd, size_t p) {
if (ttyfd < 0)
return;
while (p > 0) {
p--;
loop_write(ttyfd, "\b \b", 3, false);
}
}
int ask_password_tty(
const char *message,
usec_t until,
const char *flag_file,
char **_passphrase) {
struct termios old_termios, new_termios;
char passphrase[LINE_MAX];
size_t p = 0;
int r, ttyfd = -1, notify = -1;
struct pollfd pollfd[2];
bool reset_tty = false;
bool silent_mode = false;
bool dirty = false;
enum {
POLL_TTY,
POLL_INOTIFY
};
assert(message);
assert(_passphrase);
if (flag_file) {
if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
r = -errno;
goto finish;
}
if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
r = -errno;
goto finish;
}
}
if ((ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC)) >= 0) {
if (tcgetattr(ttyfd, &old_termios) < 0) {
r = -errno;
goto finish;
}
loop_write(ttyfd, ANSI_HIGHLIGHT_ON, sizeof(ANSI_HIGHLIGHT_ON)-1, false);
loop_write(ttyfd, message, strlen(message), false);
loop_write(ttyfd, " ", 1, false);
loop_write(ttyfd, ANSI_HIGHLIGHT_OFF, sizeof(ANSI_HIGHLIGHT_OFF)-1, 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;
}
zero(pollfd);
pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
pollfd[POLL_TTY].events = POLLIN;
pollfd[POLL_INOTIFY].fd = notify;
pollfd[POLL_INOTIFY].events = POLLIN;
for (;;) {
char c;
int sleep_for = -1, k;
ssize_t n;
if (until > 0) {
usec_t y;
y = now(CLOCK_MONOTONIC);
if (y > until) {
r = -ETIME;
goto finish;
}
sleep_for = (int) ((until - y) / USEC_PER_MSEC);
}
if (flag_file)
if (access(flag_file, F_OK) < 0) {
r = -errno;
goto finish;
}
if ((k = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 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)
flush_fd(notify);
if (pollfd[POLL_TTY].revents == 0)
continue;
if ((n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1)) < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
r = -errno;
goto finish;
} else if (n == 0)
break;
if (c == '\n')
break;
else if (c == 21) { /* C-u */
if (!silent_mode)
backspace_chars(ttyfd, p);
p = 0;
} else if (c == '\b' || c == 127) {
if (p > 0) {
if (!silent_mode)
backspace_chars(ttyfd, 1);
p--;
} else if (!dirty && !silent_mode) {
silent_mode = true;
/* There are two ways to enter silent
* mode. Either by pressing backspace
* as first key (and only as first key),
* or ... */
if (ttyfd >= 0)
loop_write(ttyfd, "(no echo) ", 10, false);
} else if (ttyfd >= 0)
loop_write(ttyfd, "\a", 1, false);
} else if (c == '\t' && !silent_mode) {
backspace_chars(ttyfd, p);
silent_mode = true;
/* ... or by pressing TAB at any time. */
if (ttyfd >= 0)
loop_write(ttyfd, "(no echo) ", 10, false);
} else {
passphrase[p++] = c;
if (!silent_mode && ttyfd >= 0)
loop_write(ttyfd, "*", 1, false);
dirty = true;
}
}
passphrase[p] = 0;
if (!(*_passphrase = strdup(passphrase))) {
r = -ENOMEM;
goto finish;
}
r = 0;
finish:
if (notify >= 0)
close_nointr_nofail(notify);
if (ttyfd >= 0) {
if (reset_tty) {
loop_write(ttyfd, "\n", 1, false);
tcsetattr(ttyfd, TCSADRAIN, &old_termios);
}
close_nointr_nofail(ttyfd);
}
return r;
}
static int create_socket(char **name) {
int fd;
union {
struct sockaddr sa;
struct sockaddr_un un;
} sa = {
.un.sun_family = AF_UNIX,
};
int one = 1, r;
char *c;
assert(name);
fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (fd < 0) {
log_error("socket() failed: %m");
return -errno;
}
snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%llu", random_ull());
RUN_WITH_UMASK(0177) {
r = bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path));
}
if (r < 0) {
r = -errno;
log_error("bind() failed: %m");
goto fail;
}
if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
r = -errno;
log_error("SO_PASSCRED failed: %m");
goto fail;
}
c = strdup(sa.un.sun_path);
if (!c) {
r = log_oom();
goto fail;
}
*name = c;
return fd;
fail:
close_nointr_nofail(fd);
return r;
}
int ask_password_agent(
const char *message,
const char *icon,
usec_t until,
bool accept_cached,
char ***_passphrases) {
enum {
FD_SOCKET,
FD_SIGNAL,
_FD_MAX
};
char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
char final[sizeof(temp)] = "";
int fd = -1, r;
FILE *f = NULL;
char *socket_name = NULL;
int socket_fd = -1, signal_fd = -1;
sigset_t mask, oldmask;
struct pollfd pollfd[_FD_MAX];
assert(_passphrases);
assert_se(sigemptyset(&mask) == 0);
sigset_add_many(&mask, SIGINT, SIGTERM, -1);
assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
mkdir_p_label("/run/systemd/ask-password", 0755);
RUN_WITH_UMASK(0022) {
fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY);
}
if (fd < 0) {
log_error("Failed to create password file: %m");
r = -errno;
goto finish;
}
fchmod(fd, 0644);
if (!(f = fdopen(fd, "w"))) {
log_error("Failed to allocate FILE: %m");
r = -errno;
goto finish;
}
fd = -1;
if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
log_error("signalfd(): %m");
r = -errno;
goto finish;
}
if ((socket_fd = create_socket(&socket_name)) < 0) {
r = socket_fd;
goto finish;
}
fprintf(f,
"[Ask]\n"
"PID=%lu\n"
"Socket=%s\n"
"AcceptCached=%i\n"
"NotAfter=%llu\n",
(unsigned long) getpid(),
socket_name,
accept_cached ? 1 : 0,
(unsigned long long) until);
if (message)
fprintf(f, "Message=%s\n", message);
if (icon)
fprintf(f, "Icon=%s\n", icon);
fflush(f);
if (ferror(f)) {
log_error("Failed to write query file: %m");
r = -errno;
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) {
log_error("Failed to rename query file: %m");
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) {
log_notice("Timed out");
r = -ETIME;
goto finish;
}
if ((k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1)) < 0) {
if (errno == EINTR)
continue;
log_error("poll() failed: %m");
r = -errno;
goto finish;
}
if (k <= 0) {
log_notice("Timed out");
r = -ETIME;
goto finish;
}
if (pollfd[FD_SIGNAL].revents & POLLIN) {
r = -EINTR;
goto finish;
}
if (pollfd[FD_SOCKET].revents != POLLIN) {
log_error("Unexpected poll() event.");
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);
if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
if (errno == EAGAIN ||
errno == EINTR)
continue;
log_error("recvmsg() failed: %m");
r = -errno;
goto finish;
}
if (n <= 0) {
log_error("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_warning("Received message without credentials. Ignoring.");
continue;
}
ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
if (ucred->uid != 0) {
log_warning("Got request from unprivileged user. Ignoring.");
continue;
}
if (passphrase[0] == '+') {
char **l;
if (n == 1)
l = strv_new("", NULL);
else
l = strv_parse_nulstr(passphrase+1, n-1);
/* An empty message refers to the empty password */
if (!l) {
r = -ENOMEM;
goto finish;
}
if (strv_length(l) <= 0) {
strv_free(l);
log_error("Invalid packet");
continue;
}
*_passphrases = l;
} else if (passphrase[0] == '-') {
r = -ECANCELED;
goto finish;
} else {
log_error("Invalid packet");
continue;
}
break;
}
r = 0;
finish:
if (fd >= 0)
close_nointr_nofail(fd);
if (socket_name) {
unlink(socket_name);
free(socket_name);
}
if (socket_fd >= 0)
close_nointr_nofail(socket_fd);
if (signal_fd >= 0)
close_nointr_nofail(signal_fd);
if (f)
fclose(f);
unlink(temp);
if (final[0])
unlink(final);
assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
return r;
}
int ask_password_auto(const char *message, const char *icon, usec_t until, bool accept_cached, char ***_passphrases) {
assert(message);
assert(_passphrases);
if (isatty(STDIN_FILENO)) {
int r;
char *s = NULL, **l = NULL;
if ((r = ask_password_tty(message, until, NULL, &s)) < 0)
return r;
l = strv_new(s, NULL);
free(s);
if (!l)
return -ENOMEM;
*_passphrases = l;
return r;
} else
return ask_password_agent(message, icon, until, accept_cached, _passphrases);
}
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