aboutsummaryrefslogtreecommitdiff
path: root/modules/pam_xauth/pam_xauth.c
diff options
context:
space:
mode:
Diffstat (limited to 'modules/pam_xauth/pam_xauth.c')
-rw-r--r--modules/pam_xauth/pam_xauth.c171
1 files changed, 112 insertions, 59 deletions
diff --git a/modules/pam_xauth/pam_xauth.c b/modules/pam_xauth/pam_xauth.c
index 0a94db4f..a64ae89f 100644
--- a/modules/pam_xauth/pam_xauth.c
+++ b/modules/pam_xauth/pam_xauth.c
@@ -35,8 +35,10 @@
#include "config.h"
#include <sys/types.h>
-#include <sys/fsuid.h>
#include <sys/wait.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
#include <errno.h>
#include <fnmatch.h>
#include <grp.h>
@@ -87,7 +89,7 @@ static const char * const xauthpaths[] = {
/* Run a given command (with a NULL-terminated argument list), feeding it the
* given input on stdin, and storing any output it generates. */
static int
-run_coprocess(const char *input, char **output,
+run_coprocess(pam_handle_t *pamh, const char *input, char **output,
uid_t uid, gid_t gid, const char *command, ...)
{
int ipipe[2], opipe[2], i;
@@ -126,9 +128,26 @@ run_coprocess(const char *input, char **output,
const char *tmp;
int maxopened;
/* Drop privileges. */
- setgid(gid);
- setgroups(0, NULL);
- setuid(uid);
+ if (setgid(gid) == -1)
+ {
+ int err = errno;
+ pam_syslog (pamh, LOG_ERR, "setgid(%lu) failed: %m",
+ (unsigned long) getegid ());
+ _exit (err);
+ }
+ if (setgroups(0, NULL) == -1)
+ {
+ int err = errno;
+ pam_syslog (pamh, LOG_ERR, "setgroups() failed: %m");
+ _exit (err);
+ }
+ if (setuid(uid) == -1)
+ {
+ int err = errno;
+ pam_syslog (pamh, LOG_ERR, "setuid(%lu) failed: %m",
+ (unsigned long) geteuid ());
+ _exit (err);
+ }
/* Initialize the argument list. */
memset(args, 0, sizeof(args));
/* Set the pipe descriptors up as stdin and stdout, and close
@@ -215,9 +234,11 @@ check_acl(pam_handle_t *pamh,
{
char path[PATH_MAX];
struct passwd *pwd;
- FILE *fp;
- int i;
- uid_t euid;
+ FILE *fp = NULL;
+ int i, fd = -1, save_errno;
+ struct stat st;
+ PAM_MODUTIL_DEF_PRIVS(privs);
+
/* Check this user's <sense> file. */
pwd = pam_modutil_getpwnam(pamh, this_user);
if (pwd == NULL) {
@@ -233,11 +254,33 @@ check_acl(pam_handle_t *pamh,
"name of user's home directory is too long");
return PAM_SESSION_ERR;
}
- euid = geteuid();
- setfsuid(pwd->pw_uid);
- fp = fopen(path, "r");
- setfsuid(euid);
- if (fp != NULL) {
+ if (pam_modutil_drop_priv(pamh, &privs, pwd))
+ return PAM_SESSION_ERR;
+ if (!stat(path, &st)) {
+ if (!S_ISREG(st.st_mode))
+ errno = EINVAL;
+ else
+ fd = open(path, O_RDONLY | O_NOCTTY);
+ }
+ save_errno = errno;
+ if (pam_modutil_regain_priv(pamh, &privs)) {
+ if (fd >= 0)
+ close(fd);
+ return PAM_SESSION_ERR;
+ }
+ if (fd >= 0) {
+ if (!fstat(fd, &st)) {
+ if (!S_ISREG(st.st_mode))
+ errno = EINVAL;
+ else
+ fp = fdopen(fd, "r");
+ }
+ if (!fp) {
+ save_errno = errno;
+ close(fd);
+ }
+ }
+ if (fp) {
char buf[LINE_MAX], *tmp;
/* Scan the file for a list of specs of users to "trust". */
while (fgets(buf, sizeof(buf), fp) != NULL) {
@@ -268,6 +311,7 @@ check_acl(pam_handle_t *pamh,
return PAM_PERM_DENIED;
} else {
/* Default to okay if the file doesn't exist. */
+ errno = save_errno;
switch (errno) {
case ENOENT:
if (noent_code == PAM_SUCCESS) {
@@ -305,7 +349,7 @@ pam_sm_open_session (pam_handle_t *pamh, int flags UNUSED,
struct passwd *tpwd, *rpwd;
int fd, i, debug = 0;
int retval = PAM_SUCCESS;
- uid_t systemuser = 499, targetuser = 0, euid;
+ uid_t systemuser = 499, targetuser = 0;
/* Parse arguments. We don't understand many, so no sense in breaking
* this into a separate function. */
@@ -463,14 +507,15 @@ pam_sm_open_session (pam_handle_t *pamh, int flags UNUSED,
xauth, "-f", cookiefile, "nlist", display,
(unsigned long) getuid(), (unsigned long) getgid());
}
- if (run_coprocess(NULL, &cookie,
+ if (run_coprocess(pamh, NULL, &cookie,
getuid(), getgid(),
xauth, "-f", cookiefile, "nlist", display,
NULL) == 0) {
- int save_errno;
#ifdef WITH_SELINUX
security_context_t context = NULL;
#endif
+ PAM_MODUTIL_DEF_PRIVS(privs);
+
/* Check that we got a cookie. If not, we get creative. */
if (((cookie == NULL) || (strlen(cookie) == 0)) &&
((strncmp(display, "localhost:", 10) == 0) ||
@@ -521,7 +566,7 @@ pam_sm_open_session (pam_handle_t *pamh, int flags UNUSED,
(unsigned long) getuid(),
(unsigned long) getgid());
}
- run_coprocess(NULL, &cookie,
+ run_coprocess(pamh, NULL, &cookie,
getuid(), getgid(),
xauth, "-f", cookiefile,
"nlist", t, NULL);
@@ -553,9 +598,10 @@ pam_sm_open_session (pam_handle_t *pamh, int flags UNUSED,
}
/* Generate a new file to hold the data. */
- euid = geteuid();
- setfsuid(tpwd->pw_uid);
-
+ if (pam_modutil_drop_priv(pamh, &privs, tpwd)) {
+ retval = PAM_SESSION_ERR;
+ goto cleanup;
+ }
#ifdef WITH_SELINUX
if (is_selinux_enabled() > 0) {
struct selabel_handle *ctx = selabel_open(SELABEL_CTX_FILE, NULL, 0);
@@ -573,31 +619,24 @@ pam_sm_open_session (pam_handle_t *pamh, int flags UNUSED,
}
}
}
+#endif /* WITH_SELINUX */
fd = mkstemp(xauthority + sizeof(XAUTHENV));
- save_errno = errno;
+ if (fd < 0)
+ pam_syslog(pamh, LOG_ERR,
+ "error creating temporary file `%s': %m",
+ xauthority + sizeof(XAUTHENV));
+#ifdef WITH_SELINUX
if (context != NULL) {
free(context);
setfscreatecon(NULL);
}
-#else
- fd = mkstemp(xauthority + sizeof(XAUTHENV));
- save_errno = errno;
-#endif
-
- setfsuid(euid);
- if (fd == -1) {
- errno = save_errno;
- pam_syslog(pamh, LOG_ERR,
- "error creating temporary file `%s': %m",
- xauthority + sizeof(XAUTHENV));
+#endif /* WITH_SELINUX */
+ if (fd >= 0)
+ close(fd);
+ if (pam_modutil_regain_priv(pamh, &privs) || fd < 0) {
retval = PAM_SESSION_ERR;
goto cleanup;
}
- /* Set permissions on the new file and dispose of the
- * descriptor. */
- if (fchown(fd, tpwd->pw_uid, tpwd->pw_gid) < 0)
- pam_syslog (pamh, LOG_ERR, "fchown: %m");
- close(fd);
/* Get a copy of the filename to save as a data item for
* removal at session-close time. */
@@ -669,7 +708,7 @@ pam_sm_open_session (pam_handle_t *pamh, int flags UNUSED,
(unsigned long) tpwd->pw_uid,
(unsigned long) tpwd->pw_gid);
}
- run_coprocess(cookie, &tmp,
+ run_coprocess(pamh, cookie, &tmp,
tpwd->pw_uid, tpwd->pw_gid,
xauth, "-f", cookiefile, "nmerge", "-", NULL);
@@ -691,42 +730,56 @@ int
pam_sm_close_session (pam_handle_t *pamh, int flags UNUSED,
int argc, const char **argv)
{
- void *cookiefile;
int i, debug = 0;
+ const char *user;
+ const void *data;
+ const char *cookiefile;
+ struct passwd *tpwd;
+ PAM_MODUTIL_DEF_PRIVS(privs);
+
+ /* Try to retrieve the name of a file we created when
+ * the session was opened. */
+ if (pam_get_data(pamh, DATANAME, &data) != PAM_SUCCESS)
+ return PAM_SUCCESS;
+ cookiefile = data;
- /* Parse arguments. We don't understand many, so no sense in breaking
- * this into a separate function. */
+ /* Parse arguments. We don't understand many, so
+ * no sense in breaking this into a separate function. */
for (i = 0; i < argc; i++) {
if (strcmp(argv[i], "debug") == 0) {
debug = 1;
continue;
}
- if (strncmp(argv[i], "xauthpath=", 10) == 0) {
+ if (strncmp(argv[i], "xauthpath=", 10) == 0)
continue;
- }
- if (strncmp(argv[i], "systemuser=", 11) == 0) {
+ if (strncmp(argv[i], "systemuser=", 11) == 0)
continue;
- }
- if (strncmp(argv[i], "targetuser=", 11) == 0) {
+ if (strncmp(argv[i], "targetuser=", 11) == 0)
continue;
- }
pam_syslog(pamh, LOG_WARNING, "unrecognized option `%s'",
argv[i]);
}
- /* Try to retrieve the name of a file we created when the session was
- * opened. */
- if (pam_get_data(pamh, DATANAME, (const void**) &cookiefile) == PAM_SUCCESS) {
- /* We'll only try to remove the file once. */
- if (strlen((char*)cookiefile) > 0) {
- if (debug) {
- pam_syslog(pamh, LOG_DEBUG, "removing `%s'",
- (char*)cookiefile);
- }
- unlink((char*)cookiefile);
- *((char*)cookiefile) = '\0';
- }
+ if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS) {
+ pam_syslog(pamh, LOG_ERR,
+ "error determining target user's name");
+ return PAM_SESSION_ERR;
+ }
+ if (!(tpwd = pam_modutil_getpwnam(pamh, user))) {
+ pam_syslog(pamh, LOG_ERR,
+ "error determining target user's UID");
+ return PAM_SESSION_ERR;
}
+
+ if (debug)
+ pam_syslog(pamh, LOG_DEBUG, "removing `%s'", cookiefile);
+ if (pam_modutil_drop_priv(pamh, &privs, tpwd))
+ return PAM_SESSION_ERR;
+ if (unlink(cookiefile) == -1 && errno != ENOENT)
+ pam_syslog(pamh, LOG_WARNING, "Couldn't remove `%s': %m", cookiefile);
+ if (pam_modutil_regain_priv(pamh, &privs))
+ return PAM_SESSION_ERR;
+
return PAM_SUCCESS;
}
generated by cgit v1.2.3 (git 2.39.1) at 2025-05-04 11:59:03 +0000