*
* Copyright (C) 1992-2006 Free Software Foundation, Inc.
* Copyright (C) 2012 SUSE Linux Products GmbH, Nuernberg
- * Copyright (C) 2016 Karel Zak <kzak@redhat.com>
+ * Copyright (C) 2016-2017 Karel Zak <kzak@redhat.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
#include <syslog.h>
#include <utmpx.h>
+#if defined(HAVE_LIBUTIL) && defined(HAVE_PTY_H) && defined(HAVE_SYS_SIGNALFD_H)
+# include <pty.h>
+# include <poll.h>
+# include <sys/signalfd.h>
+# include "all-io.h"
+# define USE_PTY
+#endif
+
#include "err.h"
#include <stdbool.h>
#include "pathnames.h"
#include "env.h"
#include "closestream.h"
+#include "strv.h"
#include "strutils.h"
#include "ttyutils.h"
#include "pwdutils.h"
+#include "optutils.h"
#include "logindefs.h"
#include "su-common.h"
+#include "debug.h"
+
+UL_DEBUG_DEFINE_MASK(su);
+UL_DEBUG_DEFINE_MASKNAMES(su) = UL_DEBUG_EMPTY_MASKNAMES;
+
+#define SU_DEBUG_INIT (1 << 1)
+#define SU_DEBUG_PAM (1 << 2)
+#define SU_DEBUG_PARENT (1 << 3)
+#define SU_DEBUG_TTY (1 << 4)
+#define SU_DEBUG_LOG (1 << 5)
+#define SU_DEBUG_MISC (1 << 6)
+#define SU_DEBUG_SIG (1 << 7)
+#define SU_DEBUG_PTY (1 << 8)
+#define SU_DEBUG_ALL 0xFFFF
+
+#define DBG(m, x) __UL_DBG(su, SU_DEBUG_, m, x)
+#define ON_DBG(m, x) __UL_DBG_CALL(su, SU_DEBUG_, m, x)
+
+
/* name of the pam configuration files. separate configs for su and su - */
#define PAM_SRVNAME_SU "su"
#define PAM_SRVNAME_SU_L "su-l"
#endif
enum {
- EXIT_CANNOT_INVOKE = 126,
- EXIT_ENOENT = 127
+ SIGTERM_IDX = 0,
+ SIGINT_IDX,
+ SIGQUIT_IDX,
+
+ SIGNALS_IDX_COUNT
};
/*
const char *tty_number; /* end of the tty_path */
char *new_user; /* wanted user */
- char *old_user; /* orginal user */
+ char *old_user; /* original user */
+
+ pid_t child; /* fork() baby */
+ int childstatus; /* wait() status */
+
+ char **env_whitelist_names; /* environment whitelist */
+ char **env_whitelist_vals;
+ struct sigaction oldact[SIGNALS_IDX_COUNT]; /* original sigactions indexed by SIG*_IDX */
+
+#ifdef USE_PTY
+ struct termios stdin_attrs; /* stdin and slave terminal runtime attributes */
+ int pty_master;
+ int pty_slave;
+ int pty_sigfd; /* signalfd() */
+ int poll_timeout;
+ struct winsize win; /* terminal window size */
+ sigset_t oldsig; /* original signal mask */
+#endif
unsigned int runuser :1, /* flase=su, true=runuser */
runuser_uopt :1, /* runuser -u specified */
isterm :1, /* is stdin terminal? */
suppress_pam_info:1, /* don't print PAM info messages (Last login, etc.). */
pam_has_session :1, /* PAM session opened */
pam_has_cred :1, /* PAM cred established */
+ pty :1, /* create pseudo-terminal */
restricted :1; /* false for root user */
};
caught_signal = sig;
}
+static void su_init_debug(void)
+{
+ __UL_INIT_DEBUG_FROM_ENV(su, SU_DEBUG_, 0, SU_DEBUG);
+}
+
static void init_tty(struct su_context *su)
{
su->isterm = isatty(STDIN_FILENO) ? 1 : 0;
+ DBG(TTY, ul_debug("initialize [is-term=%s]", su->isterm ? "true" : "false"));
if (su->isterm)
get_terminal_name(NULL, &su->tty_name, &su->tty_number);
}
+/*
+ * Note, this function has to be possible call more than once. If the child is
+ * already dead than it returns saved result from the previous call.
+ */
+static int wait_for_child(struct su_context *su)
+{
+ pid_t pid = (pid_t) -1;;
+ int status = 0;
+
+ if (su->child == (pid_t) -1)
+ return su->childstatus;
+
+ if (su->child != (pid_t) -1) {
+ /*
+ * The "su" parent process spends all time here in waitpid(),
+ * but "su --pty" uses pty_proxy_master() and waitpid() is only
+ * called to pick up child status or to react to SIGSTOP.
+ */
+ DBG(SIG, ul_debug("waiting for child [%d]...", su->child));
+ for (;;) {
+ pid = waitpid(su->child, &status, WUNTRACED);
+
+ if (pid != (pid_t) - 1 && WIFSTOPPED(status)) {
+ DBG(SIG, ul_debug(" child got SIGSTOP -- stop all session"));
+ kill(getpid(), SIGSTOP);
+ /* once we get here, we must have resumed */
+ kill(pid, SIGCONT);
+ DBG(SIG, ul_debug(" session resumed -- continue"));
+#ifdef USE_PTY
+ /* Let's go back to pty_proxy_master() */
+ if (su->pty_sigfd != -1) {
+ DBG(SIG, ul_debug(" leaving on child SIGSTOP"));
+ return 0;
+ }
+#endif
+ } else
+ break;
+ }
+ }
+ if (pid != (pid_t) -1) {
+ if (WIFSIGNALED(status)) {
+ fprintf(stderr, "%s%s\n",
+ strsignal(WTERMSIG(status)),
+ WCOREDUMP(status) ? _(" (core dumped)")
+ : "");
+ status = WTERMSIG(status) + 128;
+ } else
+ status = WEXITSTATUS(status);
+
+ DBG(SIG, ul_debug("child %d is dead", su->child));
+ su->child = (pid_t) -1; /* Don't use the PID anymore! */
+ su->childstatus = status;
+ } else if (caught_signal)
+ status = caught_signal + 128;
+ else
+ status = 1;
+
+ DBG(SIG, ul_debug("child status=%d", status));
+ return status;
+}
+
+
+#ifdef USE_PTY
+static void pty_init_slave(struct su_context *su)
+{
+ DBG(PTY, ul_debug("initialize slave"));
+
+ ioctl(su->pty_slave, TIOCSCTTY, 1);
+ close(su->pty_master);
+
+ dup2(su->pty_slave, STDIN_FILENO);
+ dup2(su->pty_slave, STDOUT_FILENO);
+ dup2(su->pty_slave, STDERR_FILENO);
+
+ close(su->pty_slave);
+ close(su->pty_sigfd);
+
+ su->pty_slave = -1;
+ su->pty_master = -1;
+ su->pty_sigfd = -1;
+
+ sigprocmask(SIG_SETMASK, &su->oldsig, NULL);
+
+ DBG(PTY, ul_debug("... initialize slave done"));
+}
+
+static void pty_create(struct su_context *su)
+{
+ struct termios slave_attrs;
+ int rc;
+
+ if (su->isterm) {
+ DBG(PTY, ul_debug("create for terminal"));
+
+ /* original setting of the current terminal */
+ if (tcgetattr(STDIN_FILENO, &su->stdin_attrs) != 0)
+ err(EXIT_FAILURE, _("failed to get terminal attributes"));
+ ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&su->win);
+ /* create master+slave */
+ rc = openpty(&su->pty_master, &su->pty_slave, NULL, &su->stdin_attrs, &su->win);
+
+ /* set the current terminal to raw mode; pty_cleanup() reverses this change on exit */
+ slave_attrs = su->stdin_attrs;
+ cfmakeraw(&slave_attrs);
+ slave_attrs.c_lflag &= ~ECHO;
+ tcsetattr(STDIN_FILENO, TCSANOW, &slave_attrs);
+ } else {
+ DBG(PTY, ul_debug("create for non-terminal"));
+ rc = openpty(&su->pty_master, &su->pty_slave, NULL, NULL, NULL);
+
+ if (!rc) {
+ tcgetattr(su->pty_slave, &slave_attrs);
+ slave_attrs.c_lflag &= ~ECHO;
+ tcsetattr(su->pty_slave, TCSANOW, &slave_attrs);
+ }
+ }
+
+ if (rc < 0)
+ err(EXIT_FAILURE, _("failed to create pseudo-terminal"));
+
+ DBG(PTY, ul_debug("pty setup done [master=%d, slave=%d]", su->pty_master, su->pty_slave));
+}
+
+static void pty_cleanup(struct su_context *su)
+{
+ struct termios rtt;
+
+ if (su->pty_master == -1 || !su->isterm)
+ return;
+
+ DBG(PTY, ul_debug("cleanup"));
+ rtt = su->stdin_attrs;
+ tcsetattr(STDIN_FILENO, TCSADRAIN, &rtt);
+}
+
+static int write_output(char *obuf, ssize_t bytes)
+{
+ DBG(PTY, ul_debug(" writing output"));
+
+ if (write_all(STDOUT_FILENO, obuf, bytes)) {
+ DBG(PTY, ul_debug(" writing output *failed*"));
+ warn(_("write failed"));
+ return -errno;
+ }
+
+ return 0;
+}
+
+static int write_to_child(struct su_context *su,
+ char *buf, size_t bufsz)
+{
+ return write_all(su->pty_master, buf, bufsz);
+}
+
+/*
+ * The su(1) is usually faster than shell, so it's a good idea to wait until
+ * the previous message has been already read by shell from slave before we
+ * write to master. This is necessary especially for EOF situation when we can
+ * send EOF to master before shell is fully initialized, to workaround this
+ * problem we wait until slave is empty. For example:
+ *
+ * echo "date" | su
+ *
+ * Unfortunately, the child (usually shell) can ignore stdin at all, so we
+ * don't wait forever to avoid dead locks...
+ *
+ * Note that su --pty is primarily designed for interactive sessions as it
+ * maintains master+slave tty stuff within the session. Use pipe to write to
+ * su(1) and assume non-interactive (tee-like) behavior is NOT well
+ * supported.
+ */
+static void write_eof_to_child(struct su_context *su)
+{
+ unsigned int tries = 0;
+ struct pollfd fds[] = {
+ { .fd = su->pty_slave, .events = POLLIN }
+ };
+ char c = DEF_EOF;
+
+ DBG(PTY, ul_debug(" waiting for empty slave"));
+ while (poll(fds, 1, 10) == 1 && tries < 8) {
+ DBG(PTY, ul_debug(" slave is not empty"));
+ xusleep(250000);
+ tries++;
+ }
+ if (tries < 8)
+ DBG(PTY, ul_debug(" slave is empty now"));
+
+ DBG(PTY, ul_debug(" sending EOF to master"));
+ write_to_child(su, &c, sizeof(char));
+}
+
+static int pty_handle_io(struct su_context *su, int fd, int *eof)
+{
+ char buf[BUFSIZ];
+ ssize_t bytes;
+
+ DBG(PTY, ul_debug("%d FD active", fd));
+ *eof = 0;
+
+ /* read from active FD */
+ bytes = read(fd, buf, sizeof(buf));
+ if (bytes < 0) {
+ if (errno == EAGAIN || errno == EINTR)
+ return 0;
+ return -errno;
+ }
+
+ if (bytes == 0) {
+ *eof = 1;
+ return 0;
+ }
+
+ /* from stdin (user) to command */
+ if (fd == STDIN_FILENO) {
+ DBG(PTY, ul_debug(" stdin --> master %zd bytes", bytes));
+
+ if (write_to_child(su, buf, bytes)) {
+ warn(_("write failed"));
+ return -errno;
+ }
+ /* without sync write_output() will write both input &
+ * shell output that looks like double echoing */
+ fdatasync(su->pty_master);
+
+ /* from command (master) to stdout */
+ } else if (fd == su->pty_master) {
+ DBG(PTY, ul_debug(" master --> stdout %zd bytes", bytes));
+ write_output(buf, bytes);
+ }
+
+ return 0;
+}
+
+static int pty_handle_signal(struct su_context *su, int fd)
+{
+ struct signalfd_siginfo info;
+ ssize_t bytes;
+
+ DBG(SIG, ul_debug("signal FD %d active", fd));
+
+ bytes = read(fd, &info, sizeof(info));
+ if (bytes != sizeof(info)) {
+ if (bytes < 0 && (errno == EAGAIN || errno == EINTR))
+ return 0;
+ return -errno;
+ }
+
+ switch (info.ssi_signo) {
+ case SIGCHLD:
+ DBG(SIG, ul_debug(" get signal SIGCHLD"));
+
+ /* The child terminated or stopped. Note that we ignore SIGCONT
+ * here, because stop/cont semantic is handled by wait_for_child() */
+ if (info.ssi_code == CLD_EXITED
+ || info.ssi_code == CLD_KILLED
+ || info.ssi_code == CLD_DUMPED
+ || info.ssi_status == SIGSTOP)
+ wait_for_child(su);
+ /* The child is dead, force poll() timeout. */
+ if (su->child == (pid_t) -1)
+ su->poll_timeout = 10;
+ return 0;
+ case SIGWINCH:
+ DBG(SIG, ul_debug(" get signal SIGWINCH"));
+ if (su->isterm) {
+ ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&su->win);
+ ioctl(su->pty_slave, TIOCSWINSZ, (char *)&su->win);
+ }
+ break;
+ case SIGTERM:
+ /* fallthrough */
+ case SIGINT:
+ /* fallthrough */
+ case SIGQUIT:
+ DBG(SIG, ul_debug(" get signal SIG{TERM,INT,QUIT}"));
+ caught_signal = info.ssi_signo;
+ /* Child termination is going to generate SIGCHILD (see above) */
+ kill(su->child, SIGTERM);
+ break;
+ default:
+ abort();
+ }
+
+ return 0;
+}
+
+static void pty_proxy_master(struct su_context *su)
+{
+ sigset_t ourset;
+ int rc = 0, ret, eof = 0;
+ enum {
+ POLLFD_SIGNAL = 0,
+ POLLFD_MASTER,
+ POLLFD_STDIN
+
+ };
+ struct pollfd pfd[] = {
+ [POLLFD_SIGNAL] = { .fd = -1, .events = POLLIN | POLLERR | POLLHUP },
+ [POLLFD_MASTER] = { .fd = su->pty_master, .events = POLLIN | POLLERR | POLLHUP },
+ [POLLFD_STDIN] = { .fd = STDIN_FILENO, .events = POLLIN | POLLERR | POLLHUP }
+ };
+
+ /* for PTY mode we use signalfd
+ *
+ * TODO: script(1) initializes this FD before fork, good or bad idea?
+ */
+ sigfillset(&ourset);
+ if (sigprocmask(SIG_BLOCK, &ourset, NULL)) {
+ warn(_("cannot block signals"));
+ caught_signal = true;
+ return;
+ }
+
+ sigemptyset(&ourset);
+ sigaddset(&ourset, SIGCHLD);
+ sigaddset(&ourset, SIGWINCH);
+ sigaddset(&ourset, SIGALRM);
+ sigaddset(&ourset, SIGTERM);
+ sigaddset(&ourset, SIGINT);
+ sigaddset(&ourset, SIGQUIT);
+
+ if ((su->pty_sigfd = signalfd(-1, &ourset, SFD_CLOEXEC)) < 0) {
+ warn(("cannot create signal file descriptor"));
+ caught_signal = true;
+ return;
+ }
+
+ pfd[POLLFD_SIGNAL].fd = su->pty_sigfd;
+ su->poll_timeout = -1;
+
+ while (!caught_signal) {
+ size_t i;
+ int errsv;
+
+ DBG(PTY, ul_debug("calling poll()"));
+
+ /* wait for input or signal */
+ ret = poll(pfd, ARRAY_SIZE(pfd), su->poll_timeout);
+ errsv = errno;
+ DBG(PTY, ul_debug("poll() rc=%d", ret));
+
+ if (ret < 0) {
+ if (errsv == EAGAIN)
+ continue;
+ warn(_("poll failed"));
+ break;
+ }
+ if (ret == 0) {
+ DBG(PTY, ul_debug("leaving poll() loop [timeout=%d]", su->poll_timeout));
+ break;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(pfd); i++) {
+ rc = 0;
+
+ if (pfd[i].revents == 0)
+ continue;
+
+ DBG(PTY, ul_debug(" active pfd[%s].fd=%d %s %s %s",
+ i == POLLFD_STDIN ? "stdin" :
+ i == POLLFD_MASTER ? "master" :
+ i == POLLFD_SIGNAL ? "signal" : "???",
+ pfd[i].fd,
+ pfd[i].revents & POLLIN ? "POLLIN" : "",
+ pfd[i].revents & POLLHUP ? "POLLHUP" : "",
+ pfd[i].revents & POLLERR ? "POLLERR" : ""));
+ switch (i) {
+ case POLLFD_STDIN:
+ case POLLFD_MASTER:
+ /* data */
+ if (pfd[i].revents & POLLIN)
+ rc = pty_handle_io(su, pfd[i].fd, &eof);
+ /* EOF maybe detected by two ways:
+ * A) poll() return POLLHUP event after close()
+ * B) read() returns 0 (no data) */
+ if ((pfd[i].revents & POLLHUP) || eof) {
+ DBG(PTY, ul_debug(" ignore FD"));
+ pfd[i].fd = -1;
+ if (i == POLLFD_STDIN) {
+ write_eof_to_child(su);
+ DBG(PTY, ul_debug(" ignore STDIN"));
+ }
+ }
+ continue;
+ case POLLFD_SIGNAL:
+ rc = pty_handle_signal(su, pfd[i].fd);
+ break;
+ }
+ if (rc)
+ break;
+ }
+ }
+
+ close(su->pty_sigfd);
+ su->pty_sigfd = -1;
+ DBG(PTY, ul_debug("poll() done [signal=%d, rc=%d]", caught_signal, rc));
+}
+#endif /* USE_PTY */
+
+
/* Log the fact that someone has run su to the user given by PW;
if SUCCESSFUL is true, they gave the correct password, etc. */
static void log_syslog(struct su_context *su, bool successful)
{
+ DBG(LOG, ul_debug("syslog logging"));
+
openlog(program_invocation_short_name, 0, LOG_AUTH);
syslog(LOG_NOTICE, "%s(to %s) %s on %s",
successful ? "" :
struct utmpx ut;
struct timeval tv;
+ DBG(LOG, ul_debug("btmp logging"));
+
memset(&ut, 0, sizeof(ut));
- strncpy(ut.ut_user,
+ str2memcpy(ut.ut_user,
su->pwd && su->pwd->pw_name ? su->pwd->pw_name : "(unknown)",
sizeof(ut.ut_user));
if (su->tty_number)
- xstrncpy(ut.ut_id, su->tty_number, sizeof(ut.ut_id));
+ str2memcpy(ut.ut_id, su->tty_number, sizeof(ut.ut_id));
if (su->tty_name)
- xstrncpy(ut.ut_line, su->tty_name, sizeof(ut.ut_line));
+ str2memcpy(ut.ut_line, su->tty_name, sizeof(ut.ut_line));
gettimeofday(&tv, NULL);
ut.ut_tv.tv_sec = tv.tv_sec;
{
const int errsv = errno;
+ DBG(PAM, ul_debug("cleanup"));
+
if (su->pam_has_session)
pam_close_session(su->pamh, 0);
if (su->pam_has_cred)
static void supam_export_environment(struct su_context *su)
{
+ char **env;
+
+ DBG(PAM, ul_debug("init environ[]"));
+
/* This is a copy but don't care to free as we exec later anyways. */
- char **env = pam_getenvlist(su->pamh);
+ env = pam_getenvlist(su->pamh);
while (env && *env) {
if (putenv(*env) != 0)
(su->simulate_login ? PAM_SRVNAME_RUNUSER_L : PAM_SRVNAME_RUNUSER) :
(su->simulate_login ? PAM_SRVNAME_SU_L : PAM_SRVNAME_SU);
+ DBG(PAM, ul_debug("start [name: %s]", srvname));
+
rc = pam_start(srvname, su->pwd->pw_name, &su->conv, &su->pamh);
if (is_pam_failure(rc))
goto done;
if (is_pam_failure(rc)) {
const char *msg;
+ DBG(PAM, ul_debug("authentication failed"));
log_btmp(su);
msg = pam_strerror(su->pamh, rc);
pam_end(su->pamh, rc);
sleep(getlogindefs_num("FAIL_DELAY", 1));
- errx(EXIT_FAILURE, "%s", msg ? msg : _("incorrect password"));
+ errx(EXIT_FAILURE, "%s", msg ? msg : _("authentication failed"));
}
}
static void supam_open_session(struct su_context *su)
{
- int rc = pam_open_session(su->pamh, 0);
+ int rc;
+
+ DBG(PAM, ul_debug("opening session"));
+ rc = pam_open_session(su->pamh, 0);
if (is_pam_failure(rc)) {
supam_cleanup(su, rc);
errx(EXIT_FAILURE, _("cannot open session: %s"),
su->pam_has_session = 1;
}
-
-static void create_watching_parent(struct su_context *su)
+static void parent_setup_signals(struct su_context *su)
{
- pid_t child;
sigset_t ourset;
- struct sigaction oldact[3];
- int status = 0;
- memset(oldact, 0, sizeof(oldact));
-
- child = fork();
- if (child == (pid_t) - 1) {
- supam_cleanup(su, PAM_ABORT);
- err(EXIT_FAILURE, _("cannot create child process"));
- }
-
- /* the child proceeds to run the shell */
- if (child == 0)
- return;
-
- /* In the parent watch the child. */
-
- /* su without pam support does not have a helper that keeps
- sitting on any directory so let's go to /. */
- if (chdir("/") != 0)
- warn(_("cannot change directory to %s"), "/");
+ /*
+ * Signals setup
+ *
+ * 1) block all signals
+ */
+ DBG(SIG, ul_debug("initialize signals"));
sigfillset(&ourset);
if (sigprocmask(SIG_BLOCK, &ourset, NULL)) {
warn(_("cannot block signals"));
caught_signal = true;
}
+
if (!caught_signal) {
struct sigaction action;
action.sa_handler = su_catch_sig;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
+
sigemptyset(&ourset);
- if (!su->same_session) {
- if (sigaddset(&ourset, SIGINT)
- || sigaddset(&ourset, SIGQUIT)) {
- warn(_("cannot set signal handler"));
- caught_signal = true;
- }
+
+ /* 2a) add wanted signals to the mask (for session) */
+ if (!su->same_session
+ && (sigaddset(&ourset, SIGINT)
+ || sigaddset(&ourset, SIGQUIT))) {
+
+ warn(_("cannot initialize signal mask for session"));
+ caught_signal = true;
}
- if (!caught_signal && (sigaddset(&ourset, SIGTERM)
- || sigaddset(&ourset, SIGALRM)
- || sigaction(SIGTERM, &action,
- &oldact[0])
- || sigprocmask(SIG_UNBLOCK, &ourset,
- NULL))) {
- warn(_("cannot set signal handler"));
+ /* 2b) add wanted generic signals to the mask */
+ if (!caught_signal
+ && (sigaddset(&ourset, SIGTERM)
+ || sigaddset(&ourset, SIGALRM))) {
+
+ warn(_("cannot initialize signal mask"));
+ caught_signal = true;
+ }
+
+ /* 3a) set signal handlers (for session) */
+ if (!caught_signal
+ && !su->same_session
+ && (sigaction(SIGINT, &action, &su->oldact[SIGINT_IDX])
+ || sigaction(SIGQUIT, &action, &su->oldact[SIGQUIT_IDX]))) {
+
+ warn(_("cannot set signal handler for session"));
caught_signal = true;
}
- if (!caught_signal && !su->same_session
- && (sigaction(SIGINT, &action, &oldact[1])
- || sigaction(SIGQUIT, &action, &oldact[2]))) {
+
+ /* 3b) set signal handlers */
+ if (!caught_signal
+ && sigaction(SIGTERM, &action, &su->oldact[SIGTERM_IDX])) {
+
warn(_("cannot set signal handler"));
caught_signal = true;
}
- }
- if (!caught_signal) {
- pid_t pid;
- for (;;) {
- pid = waitpid(child, &status, WUNTRACED);
- if (pid != (pid_t) - 1 && WIFSTOPPED(status)) {
- kill(getpid(), SIGSTOP);
- /* once we get here, we must have resumed */
- kill(pid, SIGCONT);
- } else
- break;
+ /* 4) unblock wanted signals */
+ if (!caught_signal
+ && sigprocmask(SIG_UNBLOCK, &ourset, NULL)) {
+
+ warn(_("cannot set signal mask"));
+ caught_signal = true;
}
- if (pid != (pid_t) - 1) {
- if (WIFSIGNALED(status)) {
- fprintf(stderr, "%s%s\n",
- strsignal(WTERMSIG(status)),
- WCOREDUMP(status) ? _(" (core dumped)")
- : "");
- status = WTERMSIG(status) + 128;
- } else
- status = WEXITSTATUS(status);
- } else if (caught_signal)
- status = caught_signal + 128;
- else
- status = 1;
- } else
+ }
+}
+
+
+static void create_watching_parent(struct su_context *su)
+{
+ int status;
+
+ DBG(MISC, ul_debug("forking..."));
+#ifdef USE_PTY
+ /* no-op, just save original signal mask to oldsig */
+ sigprocmask(SIG_BLOCK, NULL, &su->oldsig);
+
+ if (su->pty)
+ pty_create(su);
+#endif
+ fflush(stdout); /* ??? */
+
+ switch ((int) (su->child = fork())) {
+ case -1: /* error */
+ supam_cleanup(su, PAM_ABORT);
+#ifdef USE_PTY
+ if (su->pty)
+ pty_cleanup(su);
+#endif
+ err(EXIT_FAILURE, _("cannot create child process"));
+ break;
+
+ case 0: /* child */
+ return;
+
+ default: /* parent */
+ DBG(MISC, ul_debug("child [pid=%d]", (int) su->child));
+ break;
+ }
+
+ /* free unnecessary stuff */
+ free_getlogindefs_data();
+
+ /* In the parent watch the child. */
+
+ /* su without pam support does not have a helper that keeps
+ sitting on any directory so let's go to /. */
+ if (chdir("/") != 0)
+ warn(_("cannot change directory to %s"), "/");
+#ifdef USE_PTY
+ if (su->pty)
+ pty_proxy_master(su);
+ else
+#endif
+ parent_setup_signals(su);
+
+ /*
+ * Wait for child
+ */
+ if (!caught_signal)
+ status = wait_for_child(su);
+ else
status = 1;
- if (caught_signal) {
+ DBG(SIG, ul_debug("final child status=%d", status));
+
+ if (caught_signal && su->child != (pid_t)-1) {
fprintf(stderr, _("\nSession terminated, killing shell..."));
- kill(child, SIGTERM);
+ kill(su->child, SIGTERM);
}
supam_cleanup(su, PAM_SUCCESS);
if (caught_signal) {
- sleep(2);
- kill(child, SIGKILL);
- fprintf(stderr, _(" ...killed.\n"));
+ if (su->child != (pid_t)-1) {
+ DBG(SIG, ul_debug("killing child"));
+ sleep(2);
+ kill(su->child, SIGKILL);
+ fprintf(stderr, _(" ...killed.\n"));
+ }
/* Let's terminate itself with the received signal.
*
* value to detect situations when is necessary to cleanup (reset)
* terminal settings (kzak -- Jun 2013).
*/
+ DBG(SIG, ul_debug("restore signals setting"));
switch (caught_signal) {
case SIGTERM:
- sigaction(SIGTERM, &oldact[0], NULL);
+ sigaction(SIGTERM, &su->oldact[SIGTERM_IDX], NULL);
break;
case SIGINT:
- sigaction(SIGINT, &oldact[1], NULL);
+ sigaction(SIGINT, &su->oldact[SIGINT_IDX], NULL);
break;
case SIGQUIT:
- sigaction(SIGQUIT, &oldact[2], NULL);
+ sigaction(SIGQUIT, &su->oldact[SIGQUIT_IDX], NULL);
break;
default:
/* just in case that signal stuff initialization failed and
caught_signal = SIGKILL;
break;
}
+ DBG(SIG, ul_debug("self-send %d signal", caught_signal));
kill(getpid(), caught_signal);
}
+
+#ifdef USE_PTY
+ if (su->pty)
+ pty_cleanup(su);
+#endif
+ DBG(MISC, ul_debug("exiting [rc=%d]", status));
exit(status);
}
+/* Adds @name from the current environment to the whitelist. If @name is not
+ * set then nothing is added to the whitelist and returns 1.
+ */
+static int env_whitelist_add(struct su_context *su, const char *name)
+{
+ const char *env = getenv(name);
+
+ if (!env)
+ return 1;
+ if (strv_extend(&su->env_whitelist_names, name))
+ err_oom();
+ if (strv_extend(&su->env_whitelist_vals, env))
+ err_oom();
+ return 0;
+}
+
+static int env_whitelist_setenv(struct su_context *su, int overwrite)
+{
+ char **one;
+ size_t i = 0;
+ int rc;
+
+ STRV_FOREACH(one, su->env_whitelist_names) {
+ rc = setenv(*one, su->env_whitelist_vals[i], overwrite);
+ if (rc)
+ return rc;
+ i++;
+ }
+
+ return 0;
+}
+
+/* Creates (add to) whitelist from comma delimited string */
+static int env_whitelist_from_string(struct su_context *su, const char *str)
+{
+ char **all = strv_split(str, ",");
+ char **one;
+
+ if (!all) {
+ if (errno == ENOMEM)
+ err_oom();
+ return -EINVAL;
+ }
+
+ STRV_FOREACH(one, all)
+ env_whitelist_add(su, *one);
+ strv_free(all);
+ return 0;
+}
+
static void setenv_path(const struct passwd *pw)
{
int rc;
+ DBG(MISC, ul_debug("setting PATH"));
+
if (pw->pw_uid)
rc = logindefs_setenv("PATH", "ENV_PATH", _PATH_DEFPATH);
- else if ((rc = logindefs_setenv("PATH", "ENV_ROOTPATH", NULL)) != 0)
- rc = logindefs_setenv("PATH", "ENV_SUPATH", _PATH_DEFPATH_ROOT);
+ else if ((rc = logindefs_setenv("PATH", "ENV_SUPATH", NULL)) != 0)
+ rc = logindefs_setenv("PATH", "ENV_ROOTPATH", _PATH_DEFPATH_ROOT);
if (rc)
err(EXIT_FAILURE, _("failed to set the PATH environment variable"));
{
const struct passwd *pw = su->pwd;
+
+ DBG(MISC, ul_debug("modify environ[]"));
+
/* Leave TERM unchanged. Set HOME, SHELL, USER, LOGNAME, PATH.
- * Unset all other environment variables.
+ *
+ * Unset all other environment variables, but follow
+ * --whitelist-environment if specified.
*/
if (su->simulate_login) {
- char *term = getenv("TERM");
- if (term)
- term = xstrdup(term);
-
- environ = xmalloc((6 + ! !term) * sizeof(char *));
- environ[0] = NULL;
- if (term) {
- xsetenv("TERM", term, 1);
- free(term);
- }
-
- xsetenv("HOME", pw->pw_dir, 1);
+ /* leave TERM unchanged */
+ env_whitelist_add(su, "TERM");
+
+ /* Note that original su(1) has allocated environ[] by malloc
+ * to the number of expected variables. This seems unnecessary
+ * optimization as libc later re-alloc(current_size+2) and for
+ * empty environ[] the curren_size is zero. It seems better to
+ * keep all logic around environment in glibc's hands.
+ * --kzak [Aug 2018]
+ */
+#ifdef HAVE_CLEARENV
+ clearenv();
+#else
+ environ = NULL;
+#endif
+ /* always reset */
if (shell)
xsetenv("SHELL", shell, 1);
+
+ setenv_path(pw);
+
+ xsetenv("HOME", pw->pw_dir, 1);
xsetenv("USER", pw->pw_name, 1);
xsetenv("LOGNAME", pw->pw_name, 1);
- setenv_path(pw);
+
+ /* apply all from whitelist, but no overwrite */
+ env_whitelist_setenv(su, 0);
/* Set HOME, SHELL, and (if not becoming a superuser) USER and LOGNAME.
*/
{
int rc;
+ DBG(MISC, ul_debug("initialize groups"));
+
errno = 0;
if (ngroups)
rc = setgroups(ngroups, groups);
static void change_identity(const struct passwd *pw)
{
+ DBG(MISC, ul_debug("changing identity [GID=%d, UID=%d]", pw->pw_gid, pw->pw_uid));
+
if (setgid(pw->pw_gid))
err(EXIT_FAILURE, _("cannot set group id"));
if (setuid(pw->pw_uid))
size_t n_additional_args)
{
size_t n_args = 1 + su->fast_startup + 2 * ! !command + n_additional_args + 1;
- char const **args = xcalloc(n_args, sizeof *args);
+ const char **args = xcalloc(n_args, sizeof *args);
size_t argno = 1;
- int rc;
+
+ DBG(MISC, ul_debug("starting shell [shell=%s, command=\"%s\"%s%s]",
+ shell, command,
+ su->simulate_login ? " login" : "",
+ su->fast_startup ? " fast-start" : ""));
if (su->simulate_login) {
char *arg0;
memcpy(args + argno, additional_args, n_additional_args * sizeof *args);
args[argno + n_additional_args] = NULL;
execv(shell, (char **)args);
-
- rc = errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE;
- err(rc, _("failed to execute %s"), shell);
+ errexec(shell);
}
/* Return true if SHELL is a restricted shell (one not returned by
}
}
endusershell();
+
+ DBG(MISC, ul_debug("%s is restricted shell (not in /etc/shells)", shell));
return true;
}
static void usage_common(void)
{
- fputs(_(" -m, -p, --preserve-environment do not reset environment variables\n"), stdout);
+ fputs(_(" -m, -p, --preserve-environment do not reset environment variables\n"), stdout);
+ fputs(_(" -w, --whitelist-environment <list> don't reset specified variables\n"), stdout);
+ fputs(USAGE_SEPARATOR, stdout);
+
fputs(_(" -g, --group <group> specify the primary group\n"), stdout);
fputs(_(" -G, --supp-group <group> specify a supplemental group\n"), stdout);
fputs(USAGE_SEPARATOR, stdout);
" and do not create a new session\n"), stdout);
fputs(_(" -f, --fast pass -f to the shell (for csh or tcsh)\n"), stdout);
fputs(_(" -s, --shell <shell> run <shell> if /etc/shells allows it\n"), stdout);
+ fputs(_(" -P, --pty create a new pseudo-terminal\n"), stdout);
fputs(USAGE_SEPARATOR, stdout);
printf(USAGE_HELP_OPTIONS(33));
-
}
-static void __attribute__ ((__noreturn__)) usage_runuser(void)
+static void usage_runuser(void)
{
fputs(USAGE_HEADER, stdout);
fprintf(stdout,
fputs(USAGE_SEPARATOR, stdout);
fprintf(stdout, USAGE_MAN_TAIL("runuser(1)"));
- exit(EXIT_SUCCESS);
}
-static void __attribute__ ((__noreturn__)) usage_su(void)
+static void usage_su(void)
{
fputs(USAGE_HEADER, stdout);
fprintf(stdout,
usage_common();
fprintf(stdout, USAGE_MAN_TAIL("su(1)"));
- exit(EXIT_SUCCESS);
}
-static void usage(int mode)
+static void __attribute__((__noreturn__)) usage(int mode)
{
if (mode == SU_MODE)
usage_su();
else
usage_runuser();
+
+ exit(EXIT_SUCCESS);
}
static void load_config(void *data)
{
struct su_context *su = (struct su_context *) data;
- logindefs_load_file(su->runuser ? _PATH_LOGINDEFS_RUNUSER : _PATH_LOGINDEFS_SU);
+ DBG(MISC, ul_debug("loading logindefs"));
logindefs_load_file(_PATH_LOGINDEFS);
+ logindefs_load_file(su->runuser ? _PATH_LOGINDEFS_RUNUSER : _PATH_LOGINDEFS_SU);
}
/*
if (!gr)
errx(EXIT_FAILURE, _("group %s does not exist"), name);
+ DBG(MISC, ul_debug("add %s group [name=%s, GID=%d]", name, gr->gr_name, (int) gr->gr_gid));
+
*groups = xrealloc(*groups, sizeof(gid_t) * (*ngroups + 1));
(*groups)[*ngroups] = gr->gr_gid;
(*ngroups)++;
.conv = { supam_conv, NULL },
.runuser = (mode == RUNUSER_MODE ? 1 : 0),
.change_environment = 1,
- .new_user = DEFAULT_USER
+ .new_user = DEFAULT_USER,
+#ifdef USE_PTY
+ .pty_master = -1,
+ .pty_slave = -1,
+ .pty_sigfd = -1,
+#endif
}, *su = &_su;
int optc;
{"fast", no_argument, NULL, 'f'},
{"login", no_argument, NULL, 'l'},
{"preserve-environment", no_argument, NULL, 'p'},
+ {"pty", no_argument, NULL, 'P'},
{"shell", required_argument, NULL, 's'},
{"group", required_argument, NULL, 'g'},
{"supp-group", required_argument, NULL, 'G'},
{"user", required_argument, NULL, 'u'}, /* runuser only */
+ {"whitelist-environment", required_argument, NULL, 'w'},
{"help", no_argument, 0, 'h'},
{"version", no_argument, 0, 'V'},
{NULL, 0, NULL, 0}
};
+ static const ul_excl_t excl[] = { /* rows and cols in ASCII order */
+ { 'm', 'w' }, /* preserve-environment, whitelist-environment */
+ { 'p', 'w' }, /* preserve-environment, whitelist-environment */
+ { 0 }
+ };
+ int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
- atexit(close_stdout);
+ close_stdout_atexit();
+ su_init_debug();
su->conv.appdata_ptr = (void *) su;
while ((optc =
- getopt_long(argc, argv, "c:fg:G:lmps:u:hV", longopts,
+ getopt_long(argc, argv, "c:fg:G:lmpPs:u:hVw:", longopts,
NULL)) != -1) {
+
+ err_exclusive_options(optc, longopts, excl, excl_st);
+
switch (optc) {
case 'c':
command = optarg;
su->change_environment = false;
break;
+ case 'w':
+ env_whitelist_from_string(su, optarg);
+ break;
+
+ case 'P':
+#ifdef USE_PTY
+ su->pty = 1;
+#else
+ errx(EXIT_FAILURE, _("--pty is not supported for your system"));
+#endif
+ break;
+
case 's':
shell = optarg;
break;
usage(mode);
case 'V':
- printf(UTIL_LINUX_VERSION);
- exit(EXIT_SUCCESS);
-
+ print_version(EXIT_SUCCESS);
default:
errtryhelp(EXIT_FAILURE);
}
switch (mode) {
case RUNUSER_MODE:
- /* runuser -u <user> <command> */
+ /* runuser -u <user> <command>
+ *
+ * If -u <user> is not specified, then follow traditional su(1) behavior and
+ * fallthrough
+ */
if (su->runuser_uopt) {
if (shell || su->fast_startup || command || su->simulate_login)
errx(EXIT_FAILURE,
errx(EXIT_FAILURE, _("no command was specified"));
break;
}
- /* fallthrough if -u <user> is not specified, then follow
- * traditional su(1) behavior
- */
+ /* fallthrough */
case SU_MODE:
if (optind < argc)
su->new_user = argv[optind++];
|| !su->pwd->pw_passwd
|| !su->pwd->pw_name || !*su->pwd->pw_name
|| !su->pwd->pw_dir || !*su->pwd->pw_dir)
- errx(EXIT_FAILURE, _("user %s does not exist"), su->new_user);
+ errx(EXIT_FAILURE,
+ _("user %s does not exist or the user entry does not "
+ "contain all the required fields"), su->new_user);
su->new_user = su->pwd->pw_name;
su->old_user = xgetlogin();
/* Now we're in the child. */
change_identity(su->pwd);
- if (!su->same_session)
+ if (!su->same_session || su->pty) {
+ DBG(MISC, ul_debug("call setsid()"));
setsid();
-
+ }
+#ifdef USE_PTY
+ if (su->pty)
+ pty_init_slave(su);
+#endif
/* Set environment after pam_open_session, which may put KRB5CCNAME
into the pam_env, etc. */
projects / thirdparty / util-linux.git / blobdiff