lib-storage: Fixed mail_chroot to work when process was already chrooted there.

diff --git a/src/lib-storage/mail-storage-service.c b/src/lib-storage/mail-storage-service.c
index 8844bf0c24f8d5f584316b657dce5333eb60937b..9f5ea2f7459869f30a2a35f0ca2c393c446e2fe8 100644 (file)
--- a/src/lib-storage/mail-storage-service.c
+++ b/src/lib-storage/mail-storage-service.c
@@ -382,13 +382,12 @@ service_drop_privileges(struct mail_storage_service_user *user,
 
        rset.first_valid_gid = set->first_valid_gid;
        rset.last_valid_gid = set->last_valid_gid;
-       /* we can't chroot if we want to switch between users. there's not
-          much point either (from security point of view) */
-       rset.chroot_dir = *chroot == '\0' || keep_setuid_root ? NULL : chroot;
+       rset.chroot_dir = *chroot == '\0' ? NULL : chroot;
        rset.system_groups_user = user->system_groups_user;
 
        cur_chroot = restrict_access_get_current_chroot();
        if (cur_chroot != NULL) {
+               /* we're already chrooted. make sure the chroots are equal. */
                if (rset.chroot_dir == NULL) {
                        *error_r = "Process is already chrooted, "
                                "can't un-chroot for this user";
@@ -903,6 +902,7 @@ int mail_storage_service_next(struct mail_storage_service_ctx *ctx,
                (user->flags & MAIL_STORAGE_SERVICE_FLAG_DISALLOW_ROOT) != 0;
        bool temp_priv_drop =
                (user->flags & MAIL_STORAGE_SERVICE_FLAG_TEMP_PRIV_DROP) != 0;
+       bool use_chroot;
 
        /* variable strings are expanded in mail_user_init(),
           but we need the home and chroot sooner so do them separately here. */
@@ -918,12 +918,19 @@ int mail_storage_service_next(struct mail_storage_service_ctx *ctx,
                return -2;
        }
 
+       /* we can't chroot if we want to switch between users. there's
+          not much point either (from security point of view). but if we're
+          already chrooted, we'll just have to continue and hope that the
+          current chroot is the same as the wanted chroot */
+       use_chroot = !temp_priv_drop ||
+               restrict_access_get_current_chroot() != NULL;
+
        len = strlen(chroot);
        if (len > 2 && strcmp(chroot + len - 2, "/.") == 0 &&
            strncmp(home, chroot, len - 2) == 0) {
                /* mail_chroot = /chroot/. means that the home dir already
                   contains the chroot dir. remove it from home. */
-               if (!temp_priv_drop) {
+               if (use_chroot) {
                        home += len - 2;
                        if (*home == '\0')
                                home = "/";
@@ -932,9 +939,9 @@ int mail_storage_service_next(struct mail_storage_service_ctx *ctx,
                        set_keyval(ctx, user, "mail_home", home);
                        set_keyval(ctx, user, "mail_chroot", chroot);
                }
-       } else if (len > 0 && temp_priv_drop) {
-               /* we're dropping privileges only temporarily, so we can't
-                  chroot. fix home directory so we can access it. */
+       } else if (len > 0 && !use_chroot) {
+               /* we're not going to chroot. fix home directory so we can
+                  access it. */
                if (*home == '\0' || strcmp(home, "/") == 0)
                        home = chroot;
                else