lib-storage: If chdir to home doesn't work, chdir to root instead.

Most importantly this fixes unlink_directory() when current directory
after dropping privileges can't be open()ed.

diff --git a/src/lib-storage/mail-storage-service.c b/src/lib-storage/mail-storage-service.c
index b347e7e157ed874840b249ce6d3c135ef82e6d58..917b007f861a364a23479214c4b566ce35ec804b 100644 (file)
--- a/src/lib-storage/mail-storage-service.c
+++ b/src/lib-storage/mail-storage-service.c
@@ -691,11 +691,18 @@ mail_storage_service_init_post(struct mail_storage_service_ctx *ctx,
                /* we don't want to write core files to any users' home
                   directories since they could contain information about other
                   users' mails as well. so do no chdiring to home. */
-       } else if (*home != '\0' &&
-                  (user->flags & MAIL_STORAGE_SERVICE_FLAG_NO_CHDIR) == 0) {
+       } else if ((user->flags & MAIL_STORAGE_SERVICE_FLAG_NO_CHDIR) == 0) {
                /* If possible chdir to home directory, so that core file
-                  could be written in case we crash. */
-               if (chdir(home) < 0) {
+                  could be written in case we crash.
+
+                  fallback to chdir()ing to root directory. this is needed
+                  because the current directory may not be accessible after
+                  dropping privileges, and for example unlink_directory()
+                  requires ability to open the current directory. */
+               if (home[0] == '\0') {
+                       if (chdir("/") < 0)
+                               i_error("chdir(/) failed: %m");
+               } else if (chdir(home) < 0) {
                        if (errno == EACCES) {
                                i_error("%s", eacces_error_get("chdir",
                                                t_strconcat(home, "/", NULL)));
@@ -703,6 +710,9 @@ mail_storage_service_init_post(struct mail_storage_service_ctx *ctx,
                                i_error("chdir(%s) failed: %m", home);
                        else if (mail_set->mail_debug)
                                i_debug("Home dir not found: %s", home);
+
+                       if (chdir("/") < 0)
+                               i_error("chdir(/) failed: %m");
                }
        }