[V3,6/8] virtio-9p: Support for creating special files

diff --git a/hw/9pfs/virtio-9p-chroot.c b/hw/9pfs/virtio-9p-chroot.c
index e7f85e2..92a4917 100644
--- a/hw/9pfs/virtio-9p-chroot.c
+++ b/hw/9pfs/virtio-9p-chroot.c
@@ -193,6 +193,29 @@  static void chroot_do_open(V9fsFileObjectRequest *request, FdInfo *fd_info)
     }
 }
 
+int v9fs_create_special(FsContext *fs_ctx,
+                V9fsFileObjectRequest *request, int *error)
+{
+    int retval;
+
+    pthread_mutex_lock(&fs_ctx->chroot_mutex);
+
+    *error = 0;
+    v9fs_write_request(fs_ctx->chroot_socket, request);
+    retval = qemu_read_full(fs_ctx->chroot_socket, error, sizeof(*error));
+    if (retval != sizeof(*error)) {
+        error_report("reading from socket failed: %s", strerror(errno));
+        exit(1);
+    }
+
+    pthread_mutex_unlock(&fs_ctx->chroot_mutex);
+    if (*error) {
+        return -1;
+    } else {
+        return 0;
+    }
+}
+
 /*
  * Helper routine to create a file and return the file descriptor and
  * error status in FdInfo structure.
@@ -229,6 +252,56 @@  unset_uid:
     setfsuid(cur_uid);
 }
 
+/*
+ * Create directory, symbolic link, link, device node and regular files
+ * Similar to create, but it does not return the fd of created object
+ * Returns 0 on success, returns errno on failure
+ */
+static int chroot_do_create_special(V9fsFileObjectRequest *request)
+{
+    int cur_uid, cur_gid;
+    int retval, error;
+
+    cur_uid = geteuid();
+    cur_gid = getegid();
+
+    if (setfsuid(request->data.uid) < 0) {
+        return errno;
+    }
+    if (setfsgid(request->data.gid) < 0) {
+        error = errno;
+        goto unset_uid;
+    }
+
+    switch (request->data.type) {
+    case T_MKDIR:
+        retval = mkdir(request->path.path, request->data.mode);
+        break;
+    case T_SYMLINK:
+        retval = symlink(request->path.old_path, request->path.path);
+        break;
+    case T_LINK:
+        retval = link(request->path.old_path, request->path.path);
+        break;
+    default:
+        retval = mknod(request->path.path, request->data.mode,
+                        request->data.dev);
+        break;
+    }
+
+    if (retval < 0) {
+        error = errno;
+    } else {
+        error = 0;
+    }
+
+    setfsgid(cur_gid);
+unset_uid:
+    setfsuid(cur_uid);
+
+    return error;
+}
+
 static int chroot_daemonize(int chroot_sock)
 {
     sigset_t sigset;
@@ -263,7 +336,7 @@  static int chroot_daemonize(int chroot_sock)
  */
 int v9fs_chroot(FsContext *fs_ctx)
 {
-    int fd_pair[2], pid, chroot_sock, error;
+    int fd_pair[2], pid, chroot_sock, error, retval;
     V9fsFileObjectRequest request;
     FdInfo fd_info;
 
@@ -318,6 +391,15 @@  int v9fs_chroot(FsContext *fs_ctx)
                 error = -2;
             }
             break;
+        case T_MKDIR:
+        case T_SYMLINK:
+        case T_LINK:
+        case T_MKNOD:
+            retval = chroot_do_create_special(&request);
+            if (qemu_write_full(chroot_sock, &retval, sizeof(retval)) < 0) {
+                error = -2;
+            }
+            break;
         default:
             break;
         }
diff --git a/hw/9pfs/virtio-9p-chroot.h b/hw/9pfs/virtio-9p-chroot.h
index f5a2ca0..9a0ba88 100644
--- a/hw/9pfs/virtio-9p-chroot.h
+++ b/hw/9pfs/virtio-9p-chroot.h
@@ -36,5 +36,7 @@  typedef struct V9fsFileObjectRequest
 
 int v9fs_chroot(FsContext *fs_ctx);
 int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *or, int *error);
+int v9fs_create_special(FsContext *fs_ctx,
+                V9fsFileObjectRequest *request, int *error);
 
 #endif /* _QEMU_VIRTIO_9P_CHROOT_H */
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index 7f39b40..08fd67f 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -69,6 +69,78 @@  static int __create(FsContext *fs_ctx, const char *path, int flags,
     return fd;
 }
 
+static int __mknod(FsContext *fs_ctx, const char *path, FsCred *credp)
+{
+    V9fsFileObjectRequest request;
+    int retval, error = 0;
+
+    fill_request(&request, path, credp);
+    request.data.type = T_MKNOD;
+
+    retval = v9fs_create_special(fs_ctx, &request, &error);
+    if (retval < 0) {
+        errno = error;
+    }
+    return retval;
+}
+
+static int __mkdir(FsContext *fs_ctx, const char *path, FsCred *credp)
+{
+    V9fsFileObjectRequest request;
+    int retval, error = 0;
+
+    fill_request(&request, path, credp);
+    request.data.type = T_MKDIR;
+
+    retval = v9fs_create_special(fs_ctx, &request, &error);
+    if (retval > 0) {
+        errno = error;
+    }
+    qemu_free(request.path.path);
+    return retval;
+}
+
+static int __symlink(FsContext *fs_ctx, const char *oldpath,
+                const char *newpath, FsCred *credp)
+{
+    V9fsFileObjectRequest request;
+    int retval, error = 0;
+
+    fill_request(&request, newpath, credp);
+    request.data.type = T_SYMLINK;
+    request.data.oldpath_len = strlen(oldpath);
+    request.path.old_path = qemu_strdup(oldpath);
+
+    retval = v9fs_create_special(fs_ctx, &request, &error);
+    if (retval > 0) {
+        errno = error;
+        return 0;
+    }
+    qemu_free(request.path.old_path);
+    qemu_free(request.path.path);
+    return retval;
+}
+
+static int __link(FsContext *fs_ctx, const char *oldpath,
+                const char *newpath)
+{
+    V9fsFileObjectRequest request;
+    int retval, error = 0;
+
+    fill_request(&request, newpath, NULL);
+    request.data.type = T_LINK;
+    request.data.oldpath_len = strlen(oldpath);
+    request.path.old_path = qemu_strdup(oldpath);
+    retval = v9fs_create_special(fs_ctx, &request, &error);
+    if (retval > 0) {
+        errno = error;
+        return 0;
+    }
+    qemu_free(request.path.old_path);
+    qemu_free(request.path.path);
+    return retval;
+}
+
 static int local_lstat(FsContext *fs_ctx, const char *path, struct stat *stbuf)
 {
     int err;
@@ -286,8 +358,7 @@  static int local_mknod(FsContext *fs_ctx, const char *path, FsCred *credp)
             serrno = errno;
             goto err_end;
         }
-    } else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
-               (fs_ctx->fs_sm == SM_NONE)) {
+    } else if (fs_ctx->fs_sm == SM_NONE) {
         err = mknod(rpath(fs_ctx, path), credp->fc_mode, credp->fc_rdev);
         if (err == -1) {
             return err;
@@ -297,6 +368,12 @@  static int local_mknod(FsContext *fs_ctx, const char *path, FsCred *credp)
             serrno = errno;
             goto err_end;
         }
+    } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        err = __mknod(fs_ctx, path, credp);
+        if (err < 0) {
+            serrno = errno;
+            goto err_end;
+        }
     }
     return err;
 
@@ -323,8 +400,7 @@  static int local_mkdir(FsContext *fs_ctx, const char *path, FsCred *credp)
             serrno = errno;
             goto err_end;
         }
-    } else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
-               (fs_ctx->fs_sm == SM_NONE)) {
+    } else if (fs_ctx->fs_sm == SM_NONE) {
         err = mkdir(rpath(fs_ctx, path), credp->fc_mode);
         if (err == -1) {
             return err;
@@ -334,6 +410,12 @@  static int local_mkdir(FsContext *fs_ctx, const char *path, FsCred *credp)
             serrno = errno;
             goto err_end;
         }
+    } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        err = __mkdir(fs_ctx, path, credp);
+        if (err < 0) {
+            serrno = errno;
+            goto err_end;
+        }
     }
     return err;
 
@@ -451,23 +533,18 @@  static int local_symlink(FsContext *fs_ctx, const char *oldpath,
             serrno = errno;
             goto err_end;
         }
-    } else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
-               (fs_ctx->fs_sm == SM_NONE)) {
+    } else if (fs_ctx->fs_sm == SM_NONE) {
         err = symlink(oldpath, rpath(fs_ctx, newpath));
         if (err) {
             return err;
         }
         err = lchown(rpath(fs_ctx, newpath), credp->fc_uid, credp->fc_gid);
-        if (err == -1) {
-            /*
-             * If we fail to change ownership and if we are
-             * using security model none. Ignore the error
-             */
-            if (fs_ctx->fs_sm != SM_NONE) {
-                serrno = errno;
-                goto err_end;
-            } else
-                err = 0;
+        err = 0;
+    } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        err = __symlink(fs_ctx, oldpath, newpath, credp);
+        if (err < 0) {
+            serrno = errno;
+            goto err_end;
         }
     }
     return err;
@@ -478,24 +555,26 @@  err_end:
     return err;
 }
 
-static int local_link(FsContext *ctx, const char *oldpath, const char *newpath)
+static int local_link(FsContext *fs_ctx, const char *oldpath,
+                const char *newpath)
 {
-    char *tmp = qemu_strdup(rpath(ctx, oldpath));
     int err, serrno = 0;
 
-    if (tmp == NULL) {
-        return -ENOMEM;
-    }
-
-    err = link(tmp, rpath(ctx, newpath));
-    if (err == -1) {
-        serrno = errno;
-    }
-
-    qemu_free(tmp);
-
-    if (err == -1) {
-        errno = serrno;
+    if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        err = __link(fs_ctx, oldpath, newpath);
+        if (err < 0) {
+            serrno = errno;
+        }
+    } else {
+        char *tmp = qemu_strdup(rpath(fs_ctx, oldpath));
+        if (tmp == NULL) {
+            return -ENOMEM;
+        }
+        err = link(tmp, rpath(fs_ctx, newpath));
+        if (err == -1) {
+            serrno = errno;
+        }
+        qemu_free(tmp);
     }
 
     return err;