From e4c1c64112565a9be50008e6f28dbc41b53da740 Mon Sep 17 00:00:00 2001 From: Bandan Das Date: Wed, 28 Aug 2019 08:49:28 -0400 Subject: [PATCH] usb-mtp: add sanity checks on rootdir Currently, we don't check if rootdir exists and is accessible. Furthermore, a trailing slash results in a null "desc" string which ends up in the share not visible in the guest. Add some simple sanity checks for appropriate permissions. Also, bail out if the user does not supply an absolute path. Signed-off-by: Bandan Das Message-id: jpga7bto3on.fsf@linux.bootlegged.copy Signed-off-by: Gerd Hoffmann --- hw/usb/dev-mtp.c | 38 ++++++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 14 deletions(-) diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c index 9846e4b513..7c07295519 100644 --- a/hw/usb/dev-mtp.c +++ b/hw/usb/dev-mtp.c @@ -2038,26 +2038,36 @@ static void usb_mtp_realize(USBDevice *dev, Error **errp) { MTPState *s = USB_MTP(dev); - usb_desc_create_serial(dev); - usb_desc_init(dev); - QTAILQ_INIT(&s->objects); - if (s->desc == NULL) { - if (s->root == NULL) { - error_setg(errp, "usb-mtp: rootdir property must be configured"); - return; - } - s->desc = strrchr(s->root, '/'); - if (s->desc && s->desc[0]) { - s->desc = g_strdup(s->desc + 1); - } else { - s->desc = g_strdup("none"); - } + if ((s->root == NULL) || !g_path_is_absolute(s->root)) { + error_setg(errp, "usb-mtp: rootdir must be configured and be an absolute path"); + return; } + + if (access(s->root, R_OK) != 0) { + error_setg(errp, "usb-mtp: rootdir does not exist/not readable"); + return; + } else if (!s->readonly && access(s->root, W_OK) != 0) { + error_setg(errp, "usb-mtp: rootdir does not have write permissions"); + return; + } + /* Mark store as RW */ if (!s->readonly) { s->flags |= (1 << MTP_FLAG_WRITABLE); } + if (s->desc == NULL) { + /* + * This does not check if path exists + * but we have the checks above + */ + s->desc = g_path_get_basename(s->root); + } + + usb_desc_create_serial(dev); + usb_desc_init(dev); + QTAILQ_INIT(&s->objects); + } static const VMStateDescription vmstate_usb_mtp = {