Move check_user_shell() to pwutil.c as user_shell_valid()

This will make it possible to support a different backend which may
be used by testsudoers in the future.

plugins/sudoers/check_util.c

@@ -31,31 +31,6 @@
 
 #include "sudoers.h"
 
-/*
- * Returns true if the specified shell is allowed by /etc/shells, else false.
- */
-bool
-check_user_shell(const struct passwd *pw)
-{
-    const char *shell;
-    debug_decl(check_user_shell, SUDOERS_DEBUG_AUTH);
-
-    if (!def_runas_check_shell)
-	debug_return_bool(true);
-
-    sudo_debug_printf(SUDO_DEBUG_INFO,
-	"%s: checking /etc/shells for %s", __func__, pw->pw_shell);
-
-    setusershell();
-    while ((shell = getusershell()) != NULL) {
-	if (strcmp(shell, pw->pw_shell) == 0)
-	    debug_return_bool(true);
-    }
-    endusershell();
-
-    debug_return_bool(false);
-}
-
 /*
  * Check whether specified runchroot matches def_runchroot.
  * Returns true if matched, false if not matched and -1 on error.

plugins/sudoers/pwutil.c

@@ -1198,3 +1198,17 @@ done:
 	__func__, pw->pw_name, matched ? "" : "NOT ", group);
     debug_return_bool(matched);
 }
+
+/*
+ * Returns true if the user's shell is considered to be valid.
+ */
+bool
+user_shell_valid(const struct passwd *pw)
+{
+    debug_decl(user_shell_valid, SUDOERS_DEBUG_NSS);
+
+    if (!def_runas_check_shell)
+	debug_return_bool(true);
+
+    debug_return_bool(valid_shell(pw->pw_shell));
+}

plugins/sudoers/pwutil.h

@@ -73,5 +73,6 @@ struct cache_item *sudo_make_gritem(gid_t gid, const char *group);
 struct cache_item *sudo_make_grlist_item(const struct passwd *pw, char * const *groups);
 struct cache_item *sudo_make_gidlist_item(const struct passwd *pw, int ngids, GETGROUPS_T *gids, char * const *gidstrs, unsigned int type);
 struct cache_item *sudo_make_pwitem(uid_t uid, const char *user);
+bool valid_shell(const char *shell);
 
 #endif /* SUDOERS_PWUTIL_H */

plugins/sudoers/pwutil_impl.c

@@ -449,3 +449,26 @@ again:
 
     debug_return_ptr(&grlitem->cache);
 }
+
+/*
+ * Returns true if the specified shell is allowed by /etc/shells, else false.
+ */
+bool
+valid_shell(const char *shell)
+{
+    const char *entry;
+    debug_decl(valid_shell, SUDOERS_DEBUG_NSS);
+
+    sudo_debug_printf(SUDO_DEBUG_INFO,
+	"%s: checking /etc/shells for %s", __func__, shell);
+
+    setusershell();
+    while ((entry = getusershell()) != NULL) {
+	if (strcmp(entry, shell) == 0)
+	    debug_return_bool(true);
+    }
+    endusershell();
+
+    debug_return_bool(false);
+}
+

plugins/sudoers/regress/fuzz/fuzz_policy.c

@@ -728,13 +728,6 @@ check_user_runcwd(const char *runcwd)
     return true;
 }
 
-/* STUB */
-bool
-check_user_shell(const struct passwd *pw)
-{
-    return true;
-}
-
 /* STUB */
 void
 group_plugin_unload(void)

plugins/sudoers/sudoers.c

@@ -444,7 +444,7 @@ sudoers_check_common(struct sudoers_context *ctx, int pwflag)
 
     /* Check runas user's shell if running (or checking) a command. */
     if (ISSET(ctx->mode, MODE_RUN|MODE_CHECK)) {
-	if (!check_user_shell(ctx->runas.pw)) {
+	if (!user_shell_valid(ctx->runas.pw)) {
 	    log_warningx(ctx, SLOG_RAW_MSG|SLOG_AUDIT,
 		N_("invalid shell for user %s: %s"),
 		ctx->runas.pw->pw_name, ctx->runas.pw->pw_shell);

plugins/sudoers/sudoers.h

@@ -311,7 +311,6 @@ int check_user(struct sudoers_context *ctx, unsigned int validated, unsigned int
 bool user_is_exempt(const struct sudoers_context *ctx);
 
 /* check_util.c */
-bool check_user_shell(const struct passwd *pw);
 int check_user_runchroot(const char *runchroot);
 int check_user_runcwd(const char *runcwd);
 
@@ -373,6 +372,7 @@ int  sudo_pwutil_get_max_groups(void);
 void sudo_pwutil_set_max_groups(int);
 void sudo_pwutil_set_backend(sudo_make_pwitem_t, sudo_make_gritem_t, sudo_make_gidlist_item_t, sudo_make_grlist_item_t);
 void sudo_setspent(void);
+bool user_shell_valid(const struct passwd *pw);
 
 /* timestr.c */
 char *get_timestr(time_t, int);

plugins/sudoers/testsudoers.c

@@ -383,7 +383,7 @@ main(int argc, char *argv[])
 
     /* Validate user-specified chroot or cwd (if any) and runas user shell. */
     if (ISSET(validated, VALIDATE_SUCCESS)) {
-	if (!check_user_shell(test_ctx.runas.pw)) {
+	if (!user_shell_valid(test_ctx.runas.pw)) {
 	    printf(U_("\nInvalid shell for user %s: %s\n"),
 		test_ctx.runas.pw->pw_name, test_ctx.runas.pw->pw_shell);
 	    CLR(validated, VALIDATE_SUCCESS);