From 702c79e985e25a971d9f3f6e9a47abd9b9033a2f Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Fri, 19 Dec 2008 15:15:03 +0000 Subject: [PATCH] xend: Actually restrict a domU's access to xenstore when we mean to -- this means that in some cases it cannot be owner of its own xenstore nodes. This bug was pointed out by Daniel Berrange at Red Hat. This patch is my own more generic fix that automatically covers a range of callers (albeit the patch is arguably a bit of a hack ;-). Signed-off-by: Keir Fraser xen-unstable changeset: 18933:8c35da364ab39605839869d8eb0ac9b831c370f0 xen-unstable date: Thu Dec 18 17:18:28 2008 +0000 --- tools/python/xen/lowlevel/xs/xs.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/tools/python/xen/lowlevel/xs/xs.c b/tools/python/xen/lowlevel/xs/xs.c index b2c4b090e..b583989c7 100644 --- a/tools/python/xen/lowlevel/xs/xs.c +++ b/tools/python/xen/lowlevel/xs/xs.c @@ -336,15 +336,19 @@ static PyObject *xspy_set_permissions(XsHandle *self, PyObject *args) xs_set_error(EINVAL); goto exit; } + xsperms_n = PyList_Size(perms); - xsperms = calloc(xsperms_n, sizeof(struct xs_permissions)); + /* NB. alloc +1 so we can change the owner if necessary. */ + xsperms = calloc(xsperms_n + 1, sizeof(struct xs_permissions)); if (!xsperms) { xs_set_error(ENOMEM); goto exit; } + tuple0 = PyTuple_New(0); if (!tuple0) goto exit; + for (i = 0; i < xsperms_n; i++) { /* Read/write perms. Set these. */ int p_read = 0, p_write = 0; @@ -357,6 +361,17 @@ static PyObject *xspy_set_permissions(XsHandle *self, PyObject *args) if (p_write) xsperms[i].perms |= XS_PERM_WRITE; } + + /* + * Is the caller trying to restrict access to the first specified + * domain? If so then it cannot be owner, so we force dom0 as owner. + */ + if (xsperms_n && xsperms[0].perms && xsperms[0].id) { + memmove(&xsperms[1], &xsperms[0], xsperms_n * sizeof(*xsperms)); + xsperms[0].id = xsperms[0].perms = 0; + xsperms_n++; + } + Py_BEGIN_ALLOW_THREADS result = xs_set_permissions(xh, th, path, xsperms, xsperms_n); Py_END_ALLOW_THREADS -- 2.39.5