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--- a/modules/pam_faillock/pam_faillock.c
+++ b/modules/pam_faillock/pam_faillock.c
@@ -348,42 +348,81 @@ set_conf_opt(pam_handle_t *pamh, struct options *opts, const char *name, const c
static int
check_local_user (pam_handle_t *pamh, const char *user)
{
- struct passwd pw, *pwp;
- char buf[16384];
- int found = 0;
+ int rc;
+ size_t user_len;
FILE *fp;
- int errn;
+ char line[BUFSIZ];
- fp = fopen(PATH_PASSWD, "r");
- if (fp == NULL) {
- pam_syslog(pamh, LOG_ERR, "unable to open %s: %m",
- PATH_PASSWD);
- return -1;
+ /* Validate the user name. */
+ if ((user_len = strlen(user)) == 0) {
+ pam_syslog(pamh, LOG_NOTICE, "user name is not valid");
+ return PAM_SERVICE_ERR;
+ }
+
+ if (user_len > sizeof(line) - sizeof(":")) {
+ pam_syslog(pamh, LOG_NOTICE, "user name is too long");
+ return PAM_SERVICE_ERR;
+ }
+
+ if (strchr(user, ':') != NULL) {
+ /*
+ * "root:x" is not a local user name even if the passwd file
+ * contains a line starting with "root:x:".
+ */
+ return PAM_PERM_DENIED;
}
- for (;;) {
- errn = fgetpwent_r(fp, &pw, buf, sizeof (buf), &pwp);
- if (errn == ERANGE) {
- pam_syslog(pamh, LOG_WARNING, "%s contains very long lines; corrupted?",
- PATH_PASSWD);
+ /* Open the passwd file. */
+ FILE *file_name = "/etc/passwd";
+ if ((fp = fopen(file_name, "r")) == NULL) {
+ pam_syslog(pamh, LOG_ERR, "error opening %s: %m", file_name);
+ return PAM_SERVICE_ERR;
+ }
+
+ /*
+ * Scan the file using fgets() instead of fgetpwent_r() because
+ * the latter is not flexible enough in handling long lines
+ * in passwd files.
+ */
+ rc = PAM_PERM_DENIED;
+ while (fgets(line, sizeof(line), fp) != NULL) {
+ size_t line_len;
+ const char *str;
+
+ /*
+ * Does this line start with the user name
+ * followed by a colon?
+ */
+ if (strncmp(user, line, user_len) == 0 &&
+ line[user_len] == ':') {
+ rc = PAM_SUCCESS;
break;
}
- if (errn != 0)
- break;
- if (strcmp(pwp->pw_name, user) == 0) {
- found = 1;
+ /* Has a newline been read? */
+ line_len = strlen(line);
+ if (line_len < sizeof(line) - 1 ||
+ line[line_len - 1] == '\n') {
+ /* Yes, continue with the next line. */
+ continue;
+ }
+
+ /* No, read till the end of this line first. */
+ while ((str = fgets(line, sizeof(line), fp)) != NULL) {
+ line_len = strlen(line);
+ if (line_len == 0 ||
+ line[line_len - 1] == '\n') {
+ break;
+ }
+ }
+ if (str == NULL) {
+ /* fgets returned NULL, we are done. */
break;
}
+ /* Continue with the next line. */
}
- fclose (fp);
-
- if (errn != 0 && errn != ENOENT) {
- pam_syslog(pamh, LOG_ERR, "unable to enumerate local accounts: %m");
- return -1;
- } else {
- return found;
- }
+ fclose(fp);
+ return rc;
}
static int
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