[Qemu-devel] [V11 07/15] virtio-9p: Creating special files in chroot environment

["M. Mohan Kumar" <mohan@in.ibm.com>]

From: "M. Mohan Kumar" <mohan@in.ibm.com>

Add both chroot worker and qemu side interfaces to create special files
(directory, device nodes, links and symbolic links)

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
---
 hw/9pfs/virtio-9p-chroot-worker.c |   52 +++++++++++++++++++++++++++++++++++++
 hw/9pfs/virtio-9p-chroot.h        |    5 +++
 hw/9pfs/virtio-9p-local.c         |   37 +++++++++++++-------------
 3 files changed, 75 insertions(+), 19 deletions(-)

diff --git a/hw/9pfs/virtio-9p-chroot-worker.c b/hw/9pfs/virtio-9p-chroot-worker.c
index 581bfa95a..10f290d 100644
--- a/hw/9pfs/virtio-9p-chroot-worker.c
+++ b/hw/9pfs/virtio-9p-chroot-worker.c
@@ -123,6 +123,52 @@ unset_uid:
     return fd;
 }
 
+/*
+ * 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 as file descriptor on success and -errno on failure
+ */
+static int chroot_do_create_special(V9fsFileObjectRequest *request)
+{
+    int cur_uid, cur_gid;
+    int retval = -1;
+
+    cur_uid = geteuid();
+    cur_gid = getegid();
+
+    if (setfsuid(request->data.uid) < 0) {
+        return -errno;
+    }
+    if (setfsgid(request->data.gid) < 0) {
+        retval = -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) {
+        retval = -errno;
+    }
+    setfsgid(cur_gid);
+unset_uid:
+    setfsuid(cur_uid);
+    return retval;
+}
+
 static void chroot_daemonize(int chroot_sock)
 {
     sigset_t sigset;
@@ -220,6 +266,12 @@ int v9fs_chroot(FsContext *fs_ctx)
                 valid_fd = 1;
             }
             break;
+        case T_MKDIR:
+        case T_SYMLINK:
+        case T_LINK:
+        case T_MKNOD:
+            retval = chroot_do_create_special(&request);
+            break;
         default:
             retval = -1;
             break;
diff --git a/hw/9pfs/virtio-9p-chroot.h b/hw/9pfs/virtio-9p-chroot.h
index d5c3f37..9075361 100644
--- a/hw/9pfs/virtio-9p-chroot.h
+++ b/hw/9pfs/virtio-9p-chroot.h
@@ -5,6 +5,10 @@
 /* types for V9fsFileObjectRequest */
 #define T_OPEN      1
 #define T_CREATE    2
+#define T_MKDIR     3
+#define T_MKNOD     4
+#define T_SYMLINK   5
+#define T_LINK      6
 
 #define V9FS_FD_VALID INT_MAX
 
@@ -37,5 +41,6 @@ typedef struct V9fsFileObjectRequest
 
 int v9fs_chroot(FsContext *fs_ctx);
 int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *or);
+int v9fs_create_special(FsContext *fs_ctx, V9fsFileObjectRequest *request);
 
 #endif /* _QEMU_VIRTIO_9P_CHROOT_H */
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index 2ae08e8..a1eff5f 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -327,8 +327,7 @@ static int local_mknod(FsContext *fs_ctx, V9fsPath *dir_path,
             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, buffer), credp->fc_mode,
                 credp->fc_rdev);
         if (err == -1) {
@@ -339,6 +338,8 @@ static int local_mknod(FsContext *fs_ctx, V9fsPath *dir_path,
             serrno = errno;
             goto err_end;
         }
+    } else {
+        err = passthrough_request(fs_ctx, NULL, path, 0, credp, T_MKNOD);
     }
     goto out;
 
@@ -375,8 +376,7 @@ static int local_mkdir(FsContext *fs_ctx, V9fsPath *dir_path,
             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, buffer), credp->fc_mode);
         if (err == -1) {
             goto out;
@@ -386,6 +386,8 @@ static int local_mkdir(FsContext *fs_ctx, V9fsPath *dir_path,
             serrno = errno;
             goto err_end;
         }
+    } else {
+        err = passthrough_request(fs_ctx, NULL, path, 0, credp, T_MKDIR);
     }
     goto out;
 
@@ -524,25 +526,17 @@ 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, buffer));
         if (err) {
             goto out;
         }
         err = lchown(rpath(fs_ctx, newpath, buffer), 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 {
+        err = passthrough_request(fs_ctx, oldpath, newpath, 0, credp,
+                        T_SYMLINK);
     }
     goto out;
 
@@ -564,8 +558,13 @@ static int local_link(FsContext *ctx, V9fsPath *oldpath,
     v9fs_string_init(&newpath);
     v9fs_string_sprintf(&newpath, "%s/%s", dirpath->data, name);
 
-    ret = link(rpath(ctx, oldpath->data, buffer),
-               rpath(ctx, newpath.data, buffer1));
+    if (ctx->fs_sm == SM_PASSTHROUGH) {
+        ret = passthrough_request(ctx, oldpath->data, newpath.data, 0, NULL,
+                        T_LINK);
+    } else {
+        ret = link(rpath(ctx, oldpath->data, buffer),
+                rpath(ctx, newpath.data, buffer1));
+    }
     v9fs_string_free(&newpath);
     return ret;
 }
-- 
1.7.5.4