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Index: lib/libpam/modules/pam_exec/pam_exec.8
===================================================================
--- lib/libpam/modules/pam_exec/pam_exec.8
+++ lib/libpam/modules/pam_exec/pam_exec.8
@@ -1,5 +1,6 @@
.\" Copyright (c) 2001,2003 Networks Associates Technology, Inc.
.\" Copyright (c) 2017 Dag-Erling Smørgrav
+.\" Copyright (c) 2018 Thomas Munro
.\" All rights reserved.
.\"
.\" Portions of this software were developed for the FreeBSD Project by
@@ -72,6 +73,8 @@
.It Cm return_prog_exit_status
Use the program exit status as the return code of the pam_sm_* function.
It must be a valid return value for this function.
+.It Cm expose_authtok
+Write the authentication token to the program's standard input stream.
.It Cm --
Stop options parsing;
program and its arguments follow.
Index: lib/libpam/modules/pam_exec/pam_exec.c
===================================================================
--- lib/libpam/modules/pam_exec/pam_exec.c
+++ lib/libpam/modules/pam_exec/pam_exec.c
@@ -3,6 +3,7 @@
*
* Copyright (c) 2001,2003 Networks Associates Technology, Inc.
* Copyright (c) 2017 Dag-Erling Smørgrav
+ * Copyright (c) 2018 Thomas Munro
* All rights reserved.
*
* This software was developed for the FreeBSD Project by ThinkSec AS and
@@ -108,6 +109,7 @@
int return_prog_exit_status;
int capture_stdout;
int capture_stderr;
+ int expose_authtok;
};
static int
@@ -135,6 +137,8 @@
options->capture_stderr = 1;
} else if (strcmp((*argv)[i], "return_prog_exit_status") == 0) {
options->return_prog_exit_status = 1;
+ } else if (strcmp((*argv)[i], "expose_authtok") == 0) {
+ options->expose_authtok = 1;
} else {
if (strcmp((*argv)[i], "--") == 0) {
(*argc)--;
@@ -158,19 +162,22 @@
struct pe_opts *options)
{
char buf[PAM_MAX_MSG_SIZE];
- struct pollfd pfd[3];
+ struct pollfd pfd[4];
const void *item;
char **envlist, *envstr, *resp, **tmp;
- ssize_t rlen;
+ ssize_t rlen, wlen;
int envlen, extralen, i;
int pam_err, serrno, status;
- int chout[2], cherr[2], pd;
- nfds_t nfds;
+ int chin[2], chout[2], cherr[2], pd;
+ nfds_t nfds, nreadfds;
pid_t pid;
+ const char *authtok;
+ size_t authtok_size;
+ int rc;
pd = -1;
pid = 0;
- chout[0] = chout[1] = cherr[0] = cherr[1] = -1;
+ chin[0] = chin[1] = chout[0] = chout[1] = cherr[0] = cherr[1] = -1;
envlist = NULL;
#define OUT(ret) do { pam_err = (ret); goto out; } while (0)
@@ -235,6 +242,25 @@
openpam_log(PAM_LOG_DEBUG, "envlen = %d extralen = %d envlist = %p",
envlen, extralen, envlist);
+ /* set up pipe and get authtok if requested */
+ if (options->expose_authtok) {
+ if (pipe(chin) != 0) {
+ openpam_log(PAM_LOG_ERROR, "%s: pipe(): %m", func);
+ OUT(PAM_SYSTEM_ERR);
+ }
+ if (fcntl(chin[1], F_SETFL, O_NONBLOCK)) {
+ openpam_log(PAM_LOG_ERROR, "%s: fcntl(): %m", func);
+ OUT(PAM_SYSTEM_ERR);
+ }
+ rc = pam_get_authtok(pamh, PAM_AUTHTOK, &authtok, NULL);
+ if (rc == PAM_SUCCESS) {
+ authtok_size = strlen(authtok);
+ } else {
+ openpam_log(PAM_LOG_ERROR, "%s: pam_get_authtok(): %s", func,
+ pam_strerror(pamh, rc));
+ OUT(PAM_SYSTEM_ERR);
+ }
+ }
/* set up pipes if capture was requested */
if (options->capture_stdout) {
if (pipe(chout) != 0) {
@@ -269,9 +295,13 @@
if ((pid = pdfork(&pd, 0)) == 0) {
/* child */
- if ((chout[0] >= 0 && close(chout[0]) != 0) ||
+ if ((chin[1] >= 0 && close(chin[1]) != 0) ||
+ (chout[0] >= 0 && close(chout[0]) != 0) ||
(cherr[0] >= 0 && close(cherr[0]) != 0)) {
openpam_log(PAM_LOG_ERROR, "%s: close(): %m", func);
+ } else if (chin[0] >= 0 &&
+ dup2(chin[0], STDIN_FILENO) != STDIN_FILENO) {
+ openpam_log(PAM_LOG_ERROR, "%s: dup2(): %m", func);
} else if (dup2(chout[1], STDOUT_FILENO) != STDOUT_FILENO ||
dup2(cherr[1], STDERR_FILENO) != STDERR_FILENO) {
openpam_log(PAM_LOG_ERROR, "%s: dup2(): %m", func);
@@ -288,7 +318,9 @@
openpam_log(PAM_LOG_ERROR, "%s: pdfork(): %m", func);
OUT(PAM_SYSTEM_ERR);
}
- /* use poll() to watch the process and stdout / stderr */
+ /* use poll() to watch the process and stdin / stdout / stderr */
+ if (chin[0] >= 0)
+ close(chin[0]);
if (chout[1] >= 0)
close(chout[1]);
if (cherr[1] >= 0)
@@ -297,15 +329,23 @@
pfd[0].fd = pd;
pfd[0].events = POLLHUP;
nfds = 1;
+ nreadfds = 0;
if (options->capture_stdout) {
pfd[nfds].fd = chout[0];
pfd[nfds].events = POLLIN|POLLERR|POLLHUP;
nfds++;
+ nreadfds++;
}
if (options->capture_stderr) {
pfd[nfds].fd = cherr[0];
pfd[nfds].events = POLLIN|POLLERR|POLLHUP;
nfds++;
+ nreadfds++;
+ }
+ if (options->expose_authtok) {
+ pfd[nfds].fd = chin[1];
+ pfd[nfds].events = POLLOUT|POLLERR|POLLHUP;
+ nfds++;
}
/* loop until the process exits */
@@ -314,7 +354,8 @@
openpam_log(PAM_LOG_ERROR, "%s: poll(): %m", func);
OUT(PAM_SYSTEM_ERR);
}
- for (i = 1; i < nfds; ++i) {
+ /* are the stderr / stdout pipes ready for reading? */
+ for (i = 1; i < 1 + nreadfds; ++i) {
if ((pfd[i].revents & POLLIN) == 0)
continue;
if ((rlen = read(pfd[i].fd, buf, sizeof(buf) - 1)) < 0) {
@@ -328,6 +369,24 @@
(void)pam_prompt(pamh, pfd[i].fd == chout[0] ?
PAM_TEXT_INFO : PAM_ERROR_MSG, &resp, "%s", buf);
}
+ /* is the stdin pipe ready for writing? */
+ if (options->expose_authtok && authtok_size > 0 &&
+ (pfd[nfds - 1].revents & POLLOUT) != 0) {
+ if ((wlen = write(chin[1], authtok, authtok_size)) < 0) {
+ openpam_log(PAM_LOG_ERROR, "%s: write(): %m",
+ func);
+ OUT(PAM_SYSTEM_ERR);
+ } else {
+ authtok += wlen;
+ authtok_size -= wlen;
+ if (authtok_size == 0) {
+ /* finished writing; close and forget the pipe */
+ close(chin[1]);
+ chin[1] = -1;
+ nfds--;
+ }
+ }
+ }
} while (pfd[0].revents == 0);
/* the child process has exited */
@@ -364,6 +423,10 @@
serrno = errno;
if (pd >= 0)
close(pd);
+ if (chin[0] >= 0)
+ close(chin[0]);
+ if (chin[1] >= 0)
+ close(chin[1]);
if (chout[0] >= 0)
close(chout[0]);
if (chout[1] >= 0)

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