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From 593d796c753fea1c4cdc365273de777aff798fe9 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ian.jackson@eu.citrix.com>
Date: Tue, 3 May 2016 16:00:20 +0100
Subject: [PATCH 08/10] libxl: Do not trust frontend for vtpm in getinfo
libxl_device_vtpm_getinfo needs to examine devices without trusting
frontend-controlled data. So:
* Use /libxl to find the backend path.
* Parse the backend path to find the backend domid, rather than
reading it from the frontend.
This is part of XSA-175.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
---
tools/libxl/libxl.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 0886d92..a0aeb50 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1928,7 +1928,7 @@ int libxl_device_vtpm_getinfo(libxl_ctx *ctx,
libxl_vtpminfo *vtpminfo)
{
GC_INIT(ctx);
- char *dompath, *vtpmpath;
+ char *libxl_path, *dompath, *vtpmpath;
char *val;
int rc = 0;
@@ -1937,8 +1937,10 @@ int libxl_device_vtpm_getinfo(libxl_ctx *ctx,
vtpminfo->devid = vtpm->devid;
vtpmpath = GCSPRINTF("%s/device/vtpm/%d", dompath, vtpminfo->devid);
+ libxl_path = GCSPRINTF("%s/device/vtpm/%d",
+ libxl__xs_libxl_path(gc, domid), vtpminfo->devid);
vtpminfo->backend = xs_read(ctx->xsh, XBT_NULL,
- GCSPRINTF("%s/backend", vtpmpath), NULL);
+ GCSPRINTF("%s/backend", libxl_path), NULL);
if (!vtpminfo->backend) {
goto err;
}
@@ -1946,9 +1948,9 @@ int libxl_device_vtpm_getinfo(libxl_ctx *ctx,
goto err;
}
- val = libxl__xs_read(gc, XBT_NULL,
- GCSPRINTF("%s/backend-id", vtpmpath));
- vtpminfo->backend_id = val ? strtoul(val, NULL, 10) : -1;
+ rc = libxl__backendpath_parse_domid(gc, vtpminfo->backend,
+ &vtpminfo->backend_id);
+ if (rc) goto exit;
val = libxl__xs_read(gc, XBT_NULL,
GCSPRINTF("%s/state", vtpmpath));
--
2.1.4
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