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From d57ab22133654033ee1da89f128a81572d320985 Mon Sep 17 00:00:00 2001
From: Tomas Mraz <tmraz@fedoraproject.org>
Date: Thu, 20 Dec 2018 13:59:25 +0100
Subject: [PATCH] pam_motd: Cleanup the code and avoid unnecessary logging
The pam_motd module will not log if the default motd.d directories
are missing.
Also cleanup some code cleanliness issues and fix compilation
warnings.
* modules/pam_motd/pam_motd.c: Constification of constant strings.
(try_to_display_directory): Removed unused function.
(pam_split_string): Replace uint with unsigned int. Fix warnings.
(compare_strings): Fix warnings by proper constification.
(try_to_display_directories_with_overrides): Cleanups. Switch
off the logging if the motd.d directories are missing and they
are default ones.
(pam_sm_open_session): Cleanup warnings. Pass the information
to try_to_display_directories_with_overrides() that non-default
motd options are used.
---
modules/pam_motd/pam_motd.c | 88 ++++++++++++++++---------------------
1 file changed, 37 insertions(+), 51 deletions(-)
diff --git a/modules/pam_motd/pam_motd.c b/modules/pam_motd/pam_motd.c
index ec3ebd58..dbd718b6 100644
--- a/modules/pam_motd/pam_motd.c
+++ b/modules/pam_motd/pam_motd.c
@@ -22,6 +22,7 @@
#include <sys/stat.h>
#include <pwd.h>
#include <syslog.h>
+#include <errno.h>
#include <security/_pam_macros.h>
#include <security/pam_ext.h>
@@ -48,8 +49,8 @@ pam_sm_close_session (pam_handle_t *pamh UNUSED, int flags UNUSED,
return PAM_IGNORE;
}
-static char default_motd[] = DEFAULT_MOTD;
-static char default_motd_dir[] = DEFAULT_MOTD_D;
+static const char default_motd[] = DEFAULT_MOTD;
+static const char default_motd_dir[] = DEFAULT_MOTD_D;
static void try_to_display_fd(pam_handle_t *pamh, int fd)
{
@@ -75,28 +76,6 @@ static void try_to_display_fd(pam_handle_t *pamh, int fd)
_pam_drop(mtmp);
}
-static void try_to_display_directory(pam_handle_t *pamh, const char *dirname)
-{
- DIR *dirp;
-
- dirp = opendir(dirname);
-
- if (dirp != NULL) {
- struct dirent *entry;
-
- while ((entry = readdir(dirp))) {
- int fd = openat(dirfd(dirp), entry->d_name, O_RDONLY);
-
- if (fd >= 0) {
- try_to_display_fd(pamh, fd);
- close(fd);
- }
- }
-
- closedir(dirp);
- }
-}
-
/*
* Split a DELIM-separated string ARG into an array.
* Outputs a newly allocated array of strings OUT_ARG_SPLIT
@@ -104,14 +83,14 @@ static void try_to_display_directory(pam_handle_t *pamh, const char *dirname)
* 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 ***out_arg_split, unsigned int *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;
+ unsigned int i = 0;
+ unsigned int num_strs = 0;
int retval = 0;
delim_str[0] = delim;
@@ -126,7 +105,7 @@ static int pam_split_string(const pam_handle_t *pamh, char *arg, char delim,
arg_ptr = strchr(arg_ptr + sizeof(const char), delim);
}
- arg_split = (char **)calloc(num_strs, sizeof(char *));
+ arg_split = calloc(num_strs, sizeof(char *));
if (arg_split == NULL) {
pam_syslog(pamh, LOG_CRIT, "pam_motd: failed to allocate string array");
goto out;
@@ -180,10 +159,10 @@ static int join_dir_strings(char **strp_out, const char *a_str, const char *b_st
return retval;
}
-static int compare_strings(const void * a, const void * b)
+static int compare_strings(const void *a, const void *b)
{
- const char *a_str = *(char **)a;
- const char *b_str = *(char **)b;
+ const char *a_str = *(const char * const *)a;
+ const char *b_str = *(const char * const *)b;
if (a_str == NULL && b_str == NULL) {
return 0;
@@ -205,13 +184,13 @@ static int filter_dirents(const struct dirent *d)
}
static void try_to_display_directories_with_overrides(pam_handle_t *pamh,
- char **motd_dir_path_split, int num_motd_dirs)
+ char **motd_dir_path_split, unsigned int num_motd_dirs, int report_missing)
{
struct dirent ***dirscans = NULL;
- int *dirscans_sizes = NULL;
- int dirscans_size_total = 0;
+ unsigned int *dirscans_sizes = NULL;
+ unsigned int dirscans_size_total = 0;
char **dirnames_all = NULL;
- int i;
+ unsigned int i;
int i_dirnames = 0;
if (pamh == NULL || motd_dir_path_split == NULL) {
@@ -221,29 +200,31 @@ static void try_to_display_directories_with_overrides(pam_handle_t *pamh,
goto out;
}
- if ((dirscans = (struct dirent ***)calloc(num_motd_dirs,
- sizeof(struct dirent **))) == NULL) {
+ if ((dirscans = 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) {
+ if ((dirscans_sizes = 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]),
+ int rv;
+ rv = 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;
+ if (rv < 0) {
+ if (errno != ENOENT || report_missing) {
+ pam_syslog(pamh, LOG_ERR, "pam_motd: error scanning directory %s: %m",
+ motd_dir_path_split[i]);
+ }
+ dirscans_sizes[i] = rv;
}
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) {
+ if ((dirnames_all = calloc(dirscans_size_total, sizeof(char *))) == NULL) {
pam_syslog(pamh, LOG_CRIT, "pam_motd: failed to allocate dirname array");
goto out;
}
@@ -253,7 +234,7 @@ static void try_to_display_directories_with_overrides(pam_handle_t *pamh,
}
for (i = 0; i < num_motd_dirs; i++) {
- int j;
+ unsigned int j;
for (j = 0; j < dirscans_sizes[i]; j++) {
dirnames_all[i_dirnames] = dirscans[i][j]->d_name;
@@ -265,7 +246,7 @@ static void try_to_display_directories_with_overrides(pam_handle_t *pamh,
sizeof(const char *), compare_strings);
for (i = 0; i < dirscans_size_total; i++) {
- int j;
+ unsigned int j;
if (dirnames_all[i] == NULL) {
continue;
@@ -301,7 +282,8 @@ static void try_to_display_directories_with_overrides(pam_handle_t *pamh,
out:
_pam_drop(dirnames_all);
for (i = 0; i < num_motd_dirs; i++) {
- int j;
+ unsigned int j;
+
for (j = 0; j < dirscans_sizes[i]; j++) {
_pam_drop(dirscans[i][j]);
}
@@ -319,12 +301,13 @@ int pam_sm_open_session(pam_handle_t *pamh, int flags,
int retval = PAM_IGNORE;
const char *motd_path = NULL;
char *motd_path_copy = NULL;
- int num_motd_paths = 0;
+ unsigned 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;
+ unsigned int num_motd_dir_paths = 0;
char **motd_dir_path_split = NULL;
+ int report_missing;
if (flags & PAM_SILENT) {
return retval;
@@ -360,6 +343,9 @@ int pam_sm_open_session(pam_handle_t *pamh, int flags,
if (motd_path == NULL && motd_dir_path == NULL) {
motd_path = default_motd;
motd_dir_path = default_motd_dir;
+ report_missing = 0;
+ } else {
+ report_missing = 1;
}
if (motd_path != NULL) {
@@ -385,7 +371,7 @@ int pam_sm_open_session(pam_handle_t *pamh, int flags,
}
if (motd_path_split != NULL) {
- int i;
+ unsigned int i;
for (i = 0; i < num_motd_paths; i++) {
int fd = open(motd_path_split[i], O_RDONLY, 0);
@@ -402,7 +388,7 @@ int pam_sm_open_session(pam_handle_t *pamh, int flags,
if (motd_dir_path_split != NULL)
try_to_display_directories_with_overrides(pamh, motd_dir_path_split,
- num_motd_dir_paths);
+ num_motd_dir_paths, report_missing);
out:
_pam_drop(motd_path_copy);
--
2.37.3
From c2c0434bd634a817f2b16ce7f58fc96c04e88b03 Mon Sep 17 00:00:00 2001
From: "Dmitry V. Levin" <ldv@altlinux.org>
Date: Sun, 26 Apr 2020 11:12:59 +0000
Subject: [PATCH] pam_motd: fix NULL dereference when at least one of motd
directories is not available
* modules/pam_motd/pam_motd.c
(try_to_display_directories_with_overrides): Do not assign -1U to
dirscans_sizes[i] when scandir(motd_dir_path_split[i]) returns an error.
Resolves: https://bugzilla.altlinux.org/38389
Fixes: d57ab221 ("pam_motd: Cleanup the code and avoid unnecessary logging")
---
modules/pam_motd/pam_motd.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/modules/pam_motd/pam_motd.c b/modules/pam_motd/pam_motd.c
index df09b7d0..8147c6fd 100644
--- a/modules/pam_motd/pam_motd.c
+++ b/modules/pam_motd/pam_motd.c
@@ -219,6 +219,7 @@ static void try_to_display_directories_with_overrides(pam_handle_t *pamh,
pam_syslog(pamh, LOG_ERR, "pam_motd: error scanning directory %s: %m",
motd_dir_path_split[i]);
}
+ } else {
dirscans_sizes[i] = rv;
}
dirscans_size_total += dirscans_sizes[i];
--
2.37.3
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