<arg choice="opt">
motd=<replaceable>/path/filename</replaceable>
</arg>
+ <arg choice="opt">
+ motd_dir=<replaceable>/path/dirname.d</replaceable>
+ </arg>
</cmdsynopsis>
</refsynopsisdiv>
<para>
pam_motd is a PAM module that can be used to display
arbitrary motd (message of the day) files after a successful
- login. By default the <filename>/etc/motd</filename> file is
- shown. The message size is limited to 64KB.
+ login. By default, pam_motd shows files in the
+ following locations:
+ </para>
+ <para>
+ <simplelist type='vert'>
+ <member><filename>/etc/motd</filename></member>
+ <member><filename>/run/motd</filename></member>
+ <member><filename>/usr/lib/motd</filename></member>
+ <member><filename>/etc/motd.d/</filename></member>
+ <member><filename>/run/motd.d/</filename></member>
+ <member><filename>/usr/lib/motd.d/</filename></member>
+ </simplelist>
+ </para>
+ <para>
+ Each message size is limited to 64KB.
+ </para>
+ <para>
+ If <filename>/etc/motd</filename> does not exist,
+ then <filename>/run/motd</filename> is shown. If
+ <filename>/run/motd</filename> does not exist, then
+ <filename>/usr/lib/motd</filename> is shown.
+ </para>
+ <para>
+ Similar overriding behavior applies to the directories.
+ Files in <filename>/etc/motd.d/</filename> override files
+ with the same name in <filename>/run/motd.d/</filename> and
+ <filename>/usr/lib/motd.d/</filename>. Files in <filename>/run/motd.d/</filename>
+ override files with the same name in <filename>/usr/lib/motd.d/</filename>.
+ </para>
+ <para>
+ Files the in the directories listed above are displayed in
+ lexicographic order by name.
+ </para>
+ <para>
+ To silence a message,
+ a symbolic link with target <filename>/dev/null</filename>
+ may be placed in <filename>/etc/motd.d</filename> with
+ the same filename as the message to be silenced. Example:
+ Creating a symbolic link as follows silences <filename>/usr/lib/motd.d/my_motd</filename>.
+ </para>
+ <para>
+ <command>ln -s /dev/null /etc/motd.d/my_motd</command>
</para>
-
</refsect1>
<refsect1 id="pam_motd-options">
</term>
<listitem>
<para>
- The <filename>/path/filename</filename> file is displayed
- as message of the day.
+ The <filename>/path/filename</filename> file is displayed
+ as message of the day. Multiple paths to try can be
+ specified as a colon-separated list. By default this option
+ is set to <filename>/etc/motd:/run/motd:/usr/lib/motd</filename>.
</para>
</listitem>
</varlistentry>
<listitem>
<para>
The <filename>/path/dirname.d</filename> directory is scanned
- and each file contained inside of it is displayed.
+ and each file contained inside of it is displayed. Multiple
+ directories to scan can be specified as a colon-separated list.
+ By default this option is set to <filename>/etc/motd.d:/run/motd.d:/usr/lib/motd.d</filename>.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
- When no options are given, the default is to display both
- <filename>/etc/motd</filename> and the contents of
- <filename>/etc/motd.d</filename>. Specifying either option (or both)
- will disable this default behavior.
+ When no options are given, the default behavior applies for both
+ options. Specifying either option (or both) will disable the
+ default behavior for both options.
</para>
</refsect1>
*/
#define PAM_SM_SESSION
-#define DEFAULT_MOTD "/etc/motd"
-#define DEFAULT_MOTD_D "/etc/motd.d"
+#define DEFAULT_MOTD "/etc/motd:/run/motd:/usr/lib/motd"
+#define DEFAULT_MOTD_D "/etc/motd.d:/run/motd.d:/usr/lib/motd.d"
#include <security/pam_modules.h>
#include <security/pam_modutil.h>
}
}
+/*
+ * Split a DELIM-separated string ARG into an array.
+ * Outputs a newly allocated array of strings OUT_ARG_SPLIT
+ * and the number of strings OUT_NUM_STRS.
+ * Returns 0 in case of error, 1 in case of success.
+ */
+static int pam_split_string(const pam_handle_t *pamh, char *arg, char delim,
+ char ***out_arg_split, uint *out_num_strs)
+{
+ char *arg_extracted = NULL;
+ const char *arg_ptr = arg;
+ char **arg_split = NULL;
+ char delim_str[2];
+ int i = 0;
+ uint num_strs = 0;
+ int retval = 0;
+
+ delim_str[0] = delim;
+ delim_str[1] = '\0';
+
+ if (arg == NULL) {
+ goto out;
+ }
+
+ while (arg_ptr != NULL) {
+ num_strs++;
+ arg_ptr = strchr(arg_ptr + sizeof(const char), delim);
+ }
+
+ arg_split = (char **)calloc(num_strs, sizeof(char *));
+ if (arg_split == NULL) {
+ pam_syslog(pamh, LOG_CRIT, "pam_motd: failed to allocate string array");
+ goto out;
+ }
+
+
+ arg_extracted = strtok_r(arg, delim_str, &arg);
+ while (arg_extracted != NULL && i < num_strs) {
+ arg_split[i++] = arg_extracted;
+ arg_extracted = strtok_r(NULL, delim_str, &arg);
+ }
+
+ retval = 1;
+
+ out:
+ *out_num_strs = num_strs;
+ *out_arg_split = arg_split;
+
+ return retval;
+}
+
+/* Join A_STR and B_STR, inserting a "/" between them if one is not already trailing
+ * in A_STR or beginning B_STR. A pointer to a newly allocated string holding the
+ * joined string is returned in STRP_OUT.
+ * Returns -1 in case of error, or the number of bytes in the joined string in
+ * case of success. */
+static int join_dir_strings(char **strp_out, const char *a_str, const char *b_str)
+{
+ int has_sep = 0;
+ int retval = -1;
+ char *join_strp = NULL;
+
+ if (strp_out == NULL || a_str == NULL || b_str == NULL) {
+ goto out;
+ }
+ if (strlen(a_str) == 0) {
+ goto out;
+ }
+
+ has_sep = (a_str[strlen(a_str) - 1] == '/') || (b_str[0] == '/');
+
+ retval = asprintf(&join_strp, "%s%s%s", a_str,
+ (has_sep == 1) ? "" : "/", b_str);
+
+ if (retval < 0) {
+ goto out;
+ }
+
+ *strp_out = join_strp;
+
+ out:
+ return retval;
+}
+
+static int compare_strings(const void * a, const void * b)
+{
+ const char *a_str = *(char **)a;
+ const char *b_str = *(char **)b;
+
+ if (a_str == NULL && b_str == NULL) {
+ return 0;
+ }
+ else if (a_str == NULL) {
+ return -1;
+ }
+ else if (b_str == NULL) {
+ return 1;
+ }
+ else {
+ return strcmp(a_str, b_str);
+ }
+}
+
+static int filter_dirents(const struct dirent *d)
+{
+ return (d->d_type == DT_REG || d->d_type == DT_LNK);
+}
+
+static void try_to_display_directories_with_overrides(pam_handle_t *pamh,
+ char **motd_dir_path_split, int num_motd_dirs)
+{
+ struct dirent ***dirscans = NULL;
+ int *dirscans_sizes = NULL;
+ int dirscans_size_total = 0;
+ char **dirnames_all = NULL;
+ int i;
+ int i_dirnames = 0;
+
+ if (pamh == NULL || motd_dir_path_split == NULL) {
+ goto out;
+ }
+ if (num_motd_dirs < 1) {
+ goto out;
+ }
+
+ if ((dirscans = (struct dirent ***)calloc(num_motd_dirs,
+ sizeof(struct dirent **))) == NULL) {
+ pam_syslog(pamh, LOG_CRIT, "pam_motd: failed to allocate dirent arrays");
+ goto out;
+ }
+ if ((dirscans_sizes = (int *)calloc(num_motd_dirs, sizeof(int))) == NULL) {
+ pam_syslog(pamh, LOG_CRIT, "pam_motd: failed to allocate dirent array sizes");
+ goto out;
+ }
+
+ for (i = 0; i < num_motd_dirs; i++) {
+ dirscans_sizes[i] = scandir(motd_dir_path_split[i], &(dirscans[i]),
+ filter_dirents, alphasort);
+ if (dirscans_sizes[i] < 0) {
+ pam_syslog(pamh, LOG_ERR, "pam_motd: error scanning directory %s", motd_dir_path_split[i]);
+ dirscans_sizes[i] = 0;
+ }
+ dirscans_size_total += dirscans_sizes[i];
+ }
+
+ /* Allocate space for all file names found in the directories, including duplicates. */
+ if ((dirnames_all = (char **)calloc(dirscans_size_total,
+ sizeof(char *))) == NULL) {
+ pam_syslog(pamh, LOG_CRIT, "pam_motd: failed to allocate dirname array");
+ goto out;
+ }
+
+ for (i = 0; i < dirscans_size_total; i++) {
+ dirnames_all[i] = NULL;
+ }
+
+ for (i = 0; i < num_motd_dirs; i++) {
+ int j;
+
+ for (j = 0; j < dirscans_sizes[i]; j++) {
+ dirnames_all[i_dirnames] = dirscans[i][j]->d_name;
+ i_dirnames++;
+ }
+ }
+
+ qsort(dirnames_all, dirscans_size_total,
+ sizeof(const char *), compare_strings);
+
+ for (i = 0; i < dirscans_size_total; i++) {
+ int j;
+
+ if (dirnames_all[i] == NULL) {
+ continue;
+ }
+
+ /* Skip duplicate file names. */
+ if (i > 0 && strcmp(dirnames_all[i], dirnames_all[i - 1]) == 0) {
+ continue;
+ }
+
+ for (j = 0; j < num_motd_dirs; j++) {
+ char *abs_path = NULL;
+
+ if (join_dir_strings(&abs_path, motd_dir_path_split[j],
+ dirnames_all[i]) < 0) {
+ continue;
+ }
+
+ if (abs_path != NULL) {
+ int fd = open(abs_path, O_RDONLY, 0);
+ if (fd >= 0) {
+ try_to_display_fd(pamh, fd);
+ close(fd);
+
+ /* We displayed a file, skip to the next file name. */
+ break;
+ }
+ }
+ _pam_drop(abs_path);
+ }
+ }
+
+ out:
+ _pam_drop(dirnames_all);
+ for (i = 0; i < num_motd_dirs; i++) {
+ int j;
+ for (j = 0; j < dirscans_sizes[i]; j++) {
+ _pam_drop(dirscans[i][j]);
+ }
+ _pam_drop(dirscans[i]);
+ }
+ _pam_drop(dirscans_sizes);
+ _pam_drop(dirscans);
+
+ return;
+}
+
int pam_sm_open_session(pam_handle_t *pamh, int flags,
int argc, const char **argv)
{
int retval = PAM_IGNORE;
const char *motd_path = NULL;
+ char *motd_path_copy = NULL;
+ int num_motd_paths = 0;
+ char **motd_path_split = NULL;
const char *motd_dir_path = NULL;
+ char *motd_dir_path_copy = NULL;
+ int num_motd_dir_paths = 0;
+ char **motd_dir_path_split = NULL;
if (flags & PAM_SILENT) {
return retval;
motd_dir_path = default_motd_dir;
}
- if (motd_path != NULL) {
- int fd = open(motd_path, O_RDONLY, 0);
+ motd_path_copy = strdup(motd_path);
+ if (motd_path_copy != NULL) {
+ if (pam_split_string(pamh, motd_path_copy, ':', &motd_path_split,
+ &num_motd_paths) == 0) {
+ goto out;
+ }
+ }
+
+ motd_dir_path_copy = strdup(motd_dir_path);
+ if (motd_dir_path_copy != NULL) {
+ if (pam_split_string(pamh, motd_dir_path_copy, ':',
+ &motd_dir_path_split, &num_motd_dir_paths) == 0) {
+ goto out;
+ }
+ }
+
+ if (motd_path_split != NULL) {
+ int i;
+
+ for (i = 0; i < num_motd_paths; i++) {
+ int fd = open(motd_path_split[i], O_RDONLY, 0);
- if (fd >= 0) {
- try_to_display_fd(pamh, fd);
- close(fd);
+ if (fd >= 0) {
+ try_to_display_fd(pamh, fd);
+ close(fd);
+
+ /* We found and displayed a file, move onto next filename. */
+ break;
+ }
}
}
- if (motd_dir_path != NULL)
- try_to_display_directory(pamh, motd_dir_path);
+ if (motd_dir_path_split != NULL)
+ try_to_display_directories_with_overrides(pamh, motd_dir_path_split,
+ num_motd_dir_paths);
+
+ out:
+ _pam_drop(motd_path_copy);
+ _pam_drop(motd_path_split);
+ _pam_drop(motd_dir_path_copy);
+ _pam_drop(motd_dir_path_split);
return retval;
}
tst-pam_authsucceed
tst-pam_pwhistory1
tst-pam_time1
+tst-pam_motd
tst-pam_substack5.pamd tst-pam_substack5a.pamd tst-pam_substack5.sh \
tst-pam_assemble_line1.pamd tst-pam_assemble_line1.sh \
tst-pam_pwhistory1.pamd tst-pam_pwhistory1.sh \
- tst-pam_time1.pamd time.conf
+ tst-pam_time1.pamd time.conf \
+ tst-pam_motd.sh tst-pam_motd1.sh tst-pam_motd2.sh \
+ tst-pam_motd3.sh tst-pam_motd1.pamd \
+ tst-pam_motd2.pamd tst-pam_motd3.pamd
XTESTS = tst-pam_dispatch1 tst-pam_dispatch2 tst-pam_dispatch3 \
tst-pam_dispatch4 tst-pam_dispatch5 \
tst-pam_access1 tst-pam_access2 tst-pam_access3 \
tst-pam_access4 tst-pam_limits1 tst-pam_succeed_if1 \
tst-pam_group1 tst-pam_authfail tst-pam_authsucceed \
- tst-pam_pwhistory1 tst-pam_time1
+ tst-pam_pwhistory1 tst-pam_time1 tst-pam_motd
NOSRCTESTS = tst-pam_substack1 tst-pam_substack2 tst-pam_substack3 \
tst-pam_substack4 tst-pam_substack5 tst-pam_assemble_line1
--- /dev/null
+/*
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, and the entire permission notice in its entirety,
+ * including the disclaimer of warranties.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ * products derived from this software without specific prior
+ * written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of
+ * the GNU Public License, in which case the provisions of the GPL are
+ * required INSTEAD OF the above restrictions. (This clause is
+ * necessary due to a potential bad interaction between the GPL and
+ * the restrictions contained in a BSD-style copyright.)
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <security/pam_appl.h>
+#include <security/pam_misc.h>
+
+static struct pam_conv conv = {
+ misc_conv,
+ NULL
+};
+
+int main(int argc, char *argv[])
+{
+ pam_handle_t *pamh=NULL;
+ char *tst_arg = NULL;
+ int retval;
+
+ if (argc > 1)
+ tst_arg = argv[1];
+
+ retval = pam_start(tst_arg, NULL, &conv, &pamh);
+
+ retval = pam_open_session(pamh, 0);
+
+ retval = pam_close_session(pamh, 0);
+
+ if (pam_end(pamh,retval) != PAM_SUCCESS) { /* close Linux-PAM */
+ pamh = NULL;
+ exit(1);
+ }
+
+ return ( retval == PAM_SUCCESS ? 0:1 ); /* indicate success */
+}
--- /dev/null
+#!/bin/bash
+
+set -e
+
+./tst-pam_motd1.sh
+./tst-pam_motd2.sh
+./tst-pam_motd3.sh
--- /dev/null
+#%PAM-1.0
+session required pam_permit.so
+session optional pam_motd.so motd=tst-pam_motd1.d/etc/motd motd_dir=tst-pam_motd1.d/etc/motd.d
--- /dev/null
+#!/bin/bash
+
+TST_DIR="tst-pam_motd1.d"
+
+function tst_cleanup() {
+ rm -rf "${TST_DIR}"
+ rm -f tst-pam_motd1.out
+}
+
+mkdir -p ${TST_DIR}
+mkdir -p ${TST_DIR}/etc/motd.d
+
+# Verify the case of single motd and motd.d directory works
+echo "motd: /etc/motd" > ${TST_DIR}/etc/motd
+echo "motd: /etc/motd.d/test" > ${TST_DIR}/etc/motd.d/test
+
+./tst-pam_motd tst-pam_motd1 > tst-pam_motd1.out
+
+RET=$?
+
+motd_to_show_output=$(cat tst-pam_motd1.out | grep "motd: /etc/motd")
+if [ -z "${motd_to_show_output}" ];
+then
+ tst_cleanup
+ exit 1
+fi
+
+motd_dir_to_show_output=$(cat tst-pam_motd1.out | grep "motd: /etc/motd.d/test")
+if [ -z "${motd_dir_to_show_output}" ];
+then
+ tst_cleanup
+ exit 1
+fi
+
+tst_cleanup
+exit $RET
--- /dev/null
+#%PAM-1.0
+session required pam_permit.so
+session optional pam_motd.so motd=tst-pam_motd2.d/etc/motd:tst-pam_motd2.d/run/motd:tst-pam_motd2.d/usr/lib/motd motd_dir=tst-pam_motd2.d/etc/motd.d:tst-pam_motd2.d/run/motd.d:tst-pam_motd2.d/usr/lib/motd.d
--- /dev/null
+#!/bin/bash
+
+TST_DIR="tst-pam_motd2.d"
+
+function tst_cleanup() {
+ rm -rf "${TST_DIR}"
+ rm -f tst-pam_motd2.out
+}
+
+mkdir -p ${TST_DIR}
+mkdir -p ${TST_DIR}/etc/motd.d
+mkdir -p ${TST_DIR}/run/motd.d
+mkdir -p ${TST_DIR}/usr/lib/motd.d
+
+echo "motd: /etc/motd" > ${TST_DIR}/etc/motd
+echo "motd: /run/motd" > ${TST_DIR}/run/motd
+echo "motd: /usr/lib/motd" > ${TST_DIR}/usr/lib/motd
+
+# Drop a motd file in test directories such that every overriding
+# condition (for 3 directories in this case) will be seen.
+echo "motd: e0r0u1 in usr/lib - will show" > ${TST_DIR}/usr/lib/motd.d/e0r0u1.motd
+echo "motd: e0r1u0 in run - will show" > ${TST_DIR}/run/motd.d/e0r1u0.motd
+echo "motd: e0r1u1 in usr/lib - not show" > ${TST_DIR}/usr/lib/motd.d/e0r1u1.motd
+echo "motd: e0r1u1 in run - will show" > ${TST_DIR}/run/motd.d/e0r1u1.motd
+echo "motd: e1r0u0 in etc - will show" > ${TST_DIR}/etc/motd.d/e1r0u0.motd
+echo "motd: e1r0u1 in usr/lib - not show" > ${TST_DIR}/usr/lib/motd.d/e1r0u1.motd
+echo "motd: e1r0u1 in etc - will show" > ${TST_DIR}/etc/motd.d/e1r0u1.motd
+echo "motd: e1r1u0 in run - not show" > ${TST_DIR}/run/motd.d/e1r1u0.motd
+echo "motd: e1r1u0 in etc - will show" > ${TST_DIR}/etc/motd.d/e1r1u0.motd
+echo "motd: e1r1u1 in usr/lib - not show" > ${TST_DIR}/usr/lib/motd.d/e1r1u1.motd
+echo "motd: e1r1u1 in run - not show" > ${TST_DIR}/run/motd.d/e1r1u1.motd
+echo "motd: e1r1u1 in etc - will show" > ${TST_DIR}/etc/motd.d/e1r1u1.motd
+
+./tst-pam_motd tst-pam_motd2 > tst-pam_motd2.out
+
+RET=$?
+
+motd_to_show_output=$(cat tst-pam_motd2.out | grep "motd: /etc/motd")
+if [ -z "${motd_to_show_output}" ];
+then
+ tst_cleanup
+ exit 1
+fi
+
+motd_dir_not_show_output=$(cat tst-pam_motd2.out | grep "not show")
+if [ -n "${motd_dir_not_show_output}" ];
+then
+ tst_cleanup
+ exit 1
+fi
+
+tst_cleanup
+exit $RET
--- /dev/null
+#%PAM-1.0
+session required pam_permit.so
+session optional pam_motd.so motd=tst-pam_motd3.d/etc/motd:tst-pam_motd3.d/run/motd:tst-pam_motd3.d/usr/lib/motd motd_dir=tst-pam_motd3.d/etc/motd.d:tst-pam_motd3.d/run/motd.d:tst-pam_motd3.d/usr/lib/motd.d
--- /dev/null
+#!/bin/bash
+
+TST_DIR="tst-pam_motd3.d"
+
+function tst_cleanup() {
+ rm -rf "${TST_DIR}"
+ rm -f tst-pam_motd3.out
+}
+
+mkdir -p ${TST_DIR}
+mkdir -p ${TST_DIR}/etc/motd.d
+mkdir -p ${TST_DIR}/run/motd.d
+mkdir -p ${TST_DIR}/usr/lib/motd.d
+
+# Verify motd is still displayed when not overridden
+echo "motd: test-show in run - show" > ${TST_DIR}/run/motd.d/test-show.motd
+
+# Test overridden by a symlink to a file that isn't /dev/null; symlink target should show
+echo "motd: hidden-by-symlink in usr/lib - not show" > ${TST_DIR}/usr/lib/motd.d/hidden-by-symlink.motd
+echo "motd: test-from-symlink - show" > ${TST_DIR}/test-from-symlink.motd
+ln -sr ${TST_DIR}/test-from-symlink.motd ${TST_DIR}/run/motd.d/hidden-by-symlink.motd
+
+# Test hidden by a null symlink
+echo "motd: hidden-by-null-symlink in run - not show" > ${TST_DIR}/run/motd.d/hidden-by-null-symlink.motd
+ln -s /dev/null ${TST_DIR}/etc/motd.d/hidden-by-null-symlink.motd
+
+./tst-pam_motd tst-pam_motd3 > tst-pam_motd3.out
+
+RET=$?
+
+motd_dir_not_show_output=$(cat tst-pam_motd3.out | grep "not show")
+if [ -n "${motd_dir_not_show_output}" ];
+then
+ tst_cleanup
+ exit 1
+fi
+
+motd_test_show_output=$(cat tst-pam_motd3.out | grep "test-show.*- show")
+if [ -z "${motd_test_show_output}" ];
+then
+ tst_cleanup
+ exit 1
+fi
+
+motd_general_symlink_show_output=$(cat tst-pam_motd3.out | grep "test-from-symlink.*- show")
+if [ -z "${motd_general_symlink_show_output}" ];
+then
+ tst_cleanup
+ exit 1
+fi
+
+tst_cleanup
+exit $RET
projects / linux-pam / commitdiff