[Qemu-devel] [V6 PATCH 7/9] virtio-9p: Support for creating special files

[M. Mohan Kumar]

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

Signed-off-by: M. Mohan Kumar <address@hidden>
---
 hw/9pfs/virtio-9p-chroot-dm.c   |   57 ++++++++++++++++++++++++
 hw/9pfs/virtio-9p-chroot-qemu.c |   19 ++++++++
 hw/9pfs/virtio-9p-chroot.h      |    1 +
 hw/9pfs/virtio-9p-local.c       |   93 ++++++++++++++++++++++++++-------------
 4 files changed, 139 insertions(+), 31 deletions(-)

diff --git a/hw/9pfs/virtio-9p-chroot-dm.c b/hw/9pfs/virtio-9p-chroot-dm.c
index 985d42b..0ead017 100644
--- a/hw/9pfs/virtio-9p-chroot-dm.c
+++ b/hw/9pfs/virtio-9p-chroot-dm.c
@@ -119,6 +119,57 @@ 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 as file descriptor on success and -errno on failure in FdInfo
+ * structure
+ */
+static void chroot_do_create_special(V9fsFileObjectRequest *request,
+                FdInfo *fd_info)
+{
+    int cur_uid, cur_gid;
+
+    cur_uid = geteuid();
+    cur_gid = getegid();
+
+    fd_info->fi_fd = -1;
+    /* fd is not valid for create operations */
+    fd_info->fi_flags = FI_FD_INVALID;
+
+    if (setfsuid(request->data.uid) < 0) {
+        fd_info->fi_fd = -errno;
+        return;
+    }
+    if (setfsgid(request->data.gid) < 0) {
+        fd_info->fi_fd = -errno;
+        goto unset_uid;
+    }
+
+    switch (request->data.type) {
+    case T_MKDIR:
+        fd_info->fi_fd = mkdir(request->path.path, request->data.mode);
+        break;
+    case T_SYMLINK:
+        fd_info->fi_fd = symlink(request->path.old_path, request->path.path);
+        break;
+    case T_LINK:
+        fd_info->fi_fd = link(request->path.old_path, request->path.path);
+        break;
+    default:
+        fd_info->fi_fd = mknod(request->path.path, request->data.mode,
+                        request->data.dev);
+        break;
+    }
+
+    if (fd_info->fi_fd < 0) {
+        fd_info->fi_fd = -errno;
+    }
+    setfsgid(cur_gid);
+unset_uid:
+    setfsuid(cur_uid);
+}
+
 static int chroot_daemonize(int chroot_sock)
 {
     sigset_t sigset;
@@ -216,6 +267,12 @@ int v9fs_chroot(FsContext *fs_ctx)
         case T_CREATE:
             chroot_do_create(&request, &fd_info);
             break;
+        case T_MKDIR:
+        case T_SYMLINK:
+        case T_LINK:
+        case T_MKNOD:
+            chroot_do_create_special(&request, &fd_info);
+            break;
         default:
             fd_info.fi_flags = FI_FD_SOCKERR;
             break;
diff --git a/hw/9pfs/virtio-9p-chroot-qemu.c b/hw/9pfs/virtio-9p-chroot-qemu.c
index 41f9db2..1a42dc2 100644
--- a/hw/9pfs/virtio-9p-chroot-qemu.c
+++ b/hw/9pfs/virtio-9p-chroot-qemu.c
@@ -103,3 +103,22 @@ unlock:
     qemu_mutex_unlock(&fs_ctx->chroot_mutex);
     return fd;
 }
+
+/* Return 0 on success or -errno on error */
+int v9fs_create_special(FsContext *fs_ctx, V9fsFileObjectRequest *request)
+{
+    int fd, sock_error;
+    qemu_mutex_lock(&fs_ctx->chroot_mutex);
+    if (fs_ctx->chroot_ioerror) {
+        fd = -EIO;
+        goto unlock;
+    }
+    v9fs_write_request(fs_ctx->chroot_socket, request);
+        fd = v9fs_receivefd(fs_ctx->chroot_socket, &sock_error);
+        if (fd < 0 && sock_error) {
+            fs_ctx->chroot_ioerror = 1;
+        }
+unlock:
+        qemu_mutex_unlock(&fs_ctx->chroot_mutex);
+        return fd;
+}
diff --git a/hw/9pfs/virtio-9p-chroot.h b/hw/9pfs/virtio-9p-chroot.h
index 4592807..f113ff1 100644
--- a/hw/9pfs/virtio-9p-chroot.h
+++ b/hw/9pfs/virtio-9p-chroot.h
@@ -54,5 +54,6 @@ 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 3fed16c..c92c5dd 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -74,6 +74,28 @@ static int passthrough_create(FsContext *fs_ctx, const char 
*path, int flags,
     return fd;
 }
 
+static int passthrough_create_special(FsContext *fs_ctx, const char *oldpath,
+                const char *path, FsCred *credp, int type)
+{
+    V9fsFileObjectRequest request;
+    int retval;
+
+    retval = fill_fileobjectrequest(&request, path, credp);
+    if (retval < 0) {
+        return retval;
+    }
+    request.data.type = type;
+    if (oldpath) {
+        request.data.oldpath_len = strlen(oldpath);
+        if (strlen(oldpath) > PATH_MAX) {
+            return -ENAMETOOLONG;
+        }
+        strcpy(request.path.old_path, oldpath);
+    }
+    retval = v9fs_create_special(fs_ctx, &request);
+    return retval;
+}
+
 static int local_lstat(FsContext *fs_ctx, const char *path, struct stat *stbuf)
 {
     int err;
@@ -291,8 +313,7 @@ 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;
@@ -302,6 +323,12 @@ 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 = passthrough_create_special(fs_ctx, NULL, path, credp, T_MKNOD);
+        if (err < 0) {
+            serrno = errno;
+            goto err_end;
+        }
     }
     return err;
 
@@ -328,8 +355,7 @@ 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;
@@ -339,6 +365,12 @@ 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 = passthrough_create_special(fs_ctx, NULL, path, credp, T_MKDIR);
+        if (err < 0) {
+            serrno = errno;
+            goto err_end;
+        }
     }
     return err;
 
@@ -456,23 +488,19 @@ 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 = passthrough_create_special(fs_ctx, oldpath, newpath, credp,
+                        T_SYMLINK);
+        if (err < 0) {
+            serrno = errno;
+            goto err_end;
         }
     }
     return err;
@@ -483,24 +511,27 @@ 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 = passthrough_create_special(fs_ctx, oldpath, newpath, NULL,
+                        T_LINK);
+        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;
-- 
1.7.3.4