virtio-9p: Security model for create/open2
In the mapped security model, VirtFS server intercepts and maps
the file object create and get/set attribute requests. Files on the fileserver
will be created with VirtFS servers (QEMU) user credentials and the
client-users credentials are stored in extended attributes. On the request
to get attributes, server extracts the client-users credentials
from extended attributes and sends them to the client.
On Host/Fileserver:
-rw-------. 2 virfsuid virtfsgid 0 2010-05-11 09:19 afile
On Guest/Client:
-rw-r--r-- 2 guestuser guestuser 0 2010-05-11 12:19 afile
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/hw/virtio-9p-local.c b/hw/virtio-9p-local.c
index 74c81a6..bb5140e 100644
--- a/hw/virtio-9p-local.c
+++ b/hw/virtio-9p-local.c
@@ -95,6 +95,18 @@
return 0;
}
+static int local_post_create_passthrough(FsContext *fs_ctx, const char *path,
+ FsCred *credp)
+{
+ if (chmod(rpath(fs_ctx, path), credp->fc_mode & 07777) < 0) {
+ return -1;
+ }
+ if (chown(rpath(fs_ctx, path), credp->fc_uid, credp->fc_gid) < 0) {
+ return -1;
+ }
+ return 0;
+}
+
static ssize_t local_readlink(FsContext *ctx, const char *path,
char *buf, size_t bufsz)
{
@@ -230,9 +242,44 @@
return err;
}
-static int local_open2(FsContext *ctx, const char *path, int flags, mode_t mode)
+static int local_open2(FsContext *fs_ctx, const char *path, int flags,
+ FsCred *credp)
{
- return open(rpath(ctx, path), flags, mode);
+ int fd = -1;
+ int err = -1;
+ int serrno = 0;
+
+ /* Determine the security model */
+ if (fs_ctx->fs_sm == SM_MAPPED) {
+ fd = open(rpath(fs_ctx, path), flags, SM_LOCAL_MODE_BITS);
+ if (fd == -1) {
+ return fd;
+ }
+ credp->fc_mode = credp->fc_mode|S_IFREG;
+ /* Set cleint credentials in xattr */
+ err = local_set_xattr(rpath(fs_ctx, path), credp);
+ if (err == -1) {
+ serrno = errno;
+ goto err_end;
+ }
+ } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+ fd = open(rpath(fs_ctx, path), flags, credp->fc_mode);
+ if (fd == -1) {
+ return fd;
+ }
+ err = local_post_create_passthrough(fs_ctx, path, credp);
+ if (err == -1) {
+ serrno = errno;
+ goto err_end;
+ }
+ }
+ return fd;
+
+err_end:
+ close(fd);
+ remove(rpath(fs_ctx, path));
+ errno = serrno;
+ return err;
}
