virtio-9p: Introduces an option to specify the security model.

The new option is:

-fsdev fstype,id=myid,path=/share_path/,security_model=[mapped|passthrough]
-virtfs fstype,path=/share_path/,security_model=[mapped|passthrough],mnt_tag=tag

In the case of mapped security model, files are created with QEMU user
credentials and the client-user's credentials are saved in extended attributes.
Whereas in the case of passthrough security model, files on the
filesystem are directly created with client-user's credentials.

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

fsdev/qemu-fsdev.c

@@ -34,7 +34,7 @@ int qemu_fsdev_add(QemuOpts *opts)
         return -1;
     }
 
-     for (i = 0; i < ARRAY_SIZE(FsTypes); i++) {
+    for (i = 0; i < ARRAY_SIZE(FsTypes); i++) {
         if (strcmp(FsTypes[i].name, qemu_opt_get(opts, "fstype")) == 0) {
             break;
         }
@@ -46,10 +46,17 @@ int qemu_fsdev_add(QemuOpts *opts)
         return -1;
     }
 
+    if (qemu_opt_get(opts, "security_model") == NULL) {
+        fprintf(stderr, "fsdev: No security_model specified.\n");
+        return -1;
+    }
+
     fsle = qemu_malloc(sizeof(*fsle));
 
     fsle->fse.fsdev_id = qemu_strdup(qemu_opts_id(opts));
     fsle->fse.path = qemu_strdup(qemu_opt_get(opts, "path"));
+    fsle->fse.security_model = qemu_strdup(qemu_opt_get(opts,
+                "security_model"));
     fsle->fse.ops = FsTypes[i].ops;
 
     QTAILQ_INSERT_TAIL(&fstype_entries, fsle, next);

fsdev/qemu-fsdev.h

@@ -40,6 +40,7 @@ typedef struct FsTypeTable {
 typedef struct FsTypeEntry {
     char *fsdev_id;
     char *path;
+    char *security_model;
     FileOperations *ops;
 } FsTypeEntry;