fs: Add VirtualBox guest shared folder (vboxsf) support
VirtualBox hosts can share folders with guests, this commit adds a
VFS driver implementing the Linux-guest side of this, allowing folders
exported by the host to be mounted under Linux.
This driver depends on the guest <-> host IPC functions exported by
the vboxguest driver.
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/vboxsf/dir.c b/fs/vboxsf/dir.c
new file mode 100644
index 0000000..dd147b4
--- /dev/null
+++ b/fs/vboxsf/dir.c
@@ -0,0 +1,427 @@
+// SPDX-License-Identifier: MIT
+/*
+ * VirtualBox Guest Shared Folders support: Directory inode and file operations
+ *
+ * Copyright (C) 2006-2018 Oracle Corporation
+ */
+
+#include <linux/namei.h>
+#include <linux/vbox_utils.h>
+#include "vfsmod.h"
+
+static int vboxsf_dir_open(struct inode *inode, struct file *file)
+{
+ struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
+ struct shfl_createparms params = {};
+ struct vboxsf_dir_info *sf_d;
+ int err;
+
+ sf_d = vboxsf_dir_info_alloc();
+ if (!sf_d)
+ return -ENOMEM;
+
+ params.handle = SHFL_HANDLE_NIL;
+ params.create_flags = SHFL_CF_DIRECTORY | SHFL_CF_ACT_OPEN_IF_EXISTS |
+ SHFL_CF_ACT_FAIL_IF_NEW | SHFL_CF_ACCESS_READ;
+
+ err = vboxsf_create_at_dentry(file_dentry(file), ¶ms);
+ if (err)
+ goto err_free_dir_info;
+
+ if (params.result != SHFL_FILE_EXISTS) {
+ err = -ENOENT;
+ goto err_close;
+ }
+
+ err = vboxsf_dir_read_all(sbi, sf_d, params.handle);
+ if (err)
+ goto err_close;
+
+ vboxsf_close(sbi->root, params.handle);
+ file->private_data = sf_d;
+ return 0;
+
+err_close:
+ vboxsf_close(sbi->root, params.handle);
+err_free_dir_info:
+ vboxsf_dir_info_free(sf_d);
+ return err;
+}
+
+static int vboxsf_dir_release(struct inode *inode, struct file *file)
+{
+ if (file->private_data)
+ vboxsf_dir_info_free(file->private_data);
+
+ return 0;
+}
+
+static unsigned int vboxsf_get_d_type(u32 mode)
+{
+ unsigned int d_type;
+
+ switch (mode & SHFL_TYPE_MASK) {
+ case SHFL_TYPE_FIFO:
+ d_type = DT_FIFO;
+ break;
+ case SHFL_TYPE_DEV_CHAR:
+ d_type = DT_CHR;
+ break;
+ case SHFL_TYPE_DIRECTORY:
+ d_type = DT_DIR;
+ break;
+ case SHFL_TYPE_DEV_BLOCK:
+ d_type = DT_BLK;
+ break;
+ case SHFL_TYPE_FILE:
+ d_type = DT_REG;
+ break;
+ case SHFL_TYPE_SYMLINK:
+ d_type = DT_LNK;
+ break;
+ case SHFL_TYPE_SOCKET:
+ d_type = DT_SOCK;
+ break;
+ case SHFL_TYPE_WHITEOUT:
+ d_type = DT_WHT;
+ break;
+ default:
+ d_type = DT_UNKNOWN;
+ break;
+ }
+ return d_type;
+}
+
+static bool vboxsf_dir_emit(struct file *dir, struct dir_context *ctx)
+{
+ struct vboxsf_sbi *sbi = VBOXSF_SBI(file_inode(dir)->i_sb);
+ struct vboxsf_dir_info *sf_d = dir->private_data;
+ struct shfl_dirinfo *info;
+ struct vboxsf_dir_buf *b;
+ unsigned int d_type;
+ loff_t i, cur = 0;
+ ino_t fake_ino;
+ void *end;
+ int err;
+
+ list_for_each_entry(b, &sf_d->info_list, head) {
+try_next_entry:
+ if (ctx->pos >= cur + b->entries) {
+ cur += b->entries;
+ continue;
+ }
+
+ /*
+ * Note the vboxsf_dir_info objects we are iterating over here
+ * are variable sized, so the info pointer may end up being
+ * unaligned. This is how we get the data from the host.
+ * Since vboxsf is only supported on x86 machines this is not
+ * a problem.
+ */
+ for (i = 0, info = b->buf; i < ctx->pos - cur; i++) {
+ end = &info->name.string.utf8[info->name.size];
+ /* Only happens if the host gives us corrupt data */
+ if (WARN_ON(end > (b->buf + b->used)))
+ return false;
+ info = end;
+ }
+
+ end = &info->name.string.utf8[info->name.size];
+ if (WARN_ON(end > (b->buf + b->used)))
+ return false;
+
+ /* Info now points to the right entry, emit it. */
+ d_type = vboxsf_get_d_type(info->info.attr.mode);
+
+ /*
+ * On 32 bit systems pos is 64 signed, while ino is 32 bit
+ * unsigned so fake_ino may overflow, check for this.
+ */
+ if ((ino_t)(ctx->pos + 1) != (u64)(ctx->pos + 1)) {
+ vbg_err("vboxsf: fake ino overflow, truncating dir\n");
+ return false;
+ }
+ fake_ino = ctx->pos + 1;
+
+ if (sbi->nls) {
+ char d_name[NAME_MAX];
+
+ err = vboxsf_nlscpy(sbi, d_name, NAME_MAX,
+ info->name.string.utf8,
+ info->name.length);
+ if (err) {
+ /* skip erroneous entry and proceed */
+ ctx->pos += 1;
+ goto try_next_entry;
+ }
+
+ return dir_emit(ctx, d_name, strlen(d_name),
+ fake_ino, d_type);
+ }
+
+ return dir_emit(ctx, info->name.string.utf8, info->name.length,
+ fake_ino, d_type);
+ }
+
+ return false;
+}
+
+static int vboxsf_dir_iterate(struct file *dir, struct dir_context *ctx)
+{
+ bool emitted;
+
+ do {
+ emitted = vboxsf_dir_emit(dir, ctx);
+ if (emitted)
+ ctx->pos += 1;
+ } while (emitted);
+
+ return 0;
+}
+
+const struct file_operations vboxsf_dir_fops = {
+ .open = vboxsf_dir_open,
+ .iterate = vboxsf_dir_iterate,
+ .release = vboxsf_dir_release,
+ .read = generic_read_dir,
+ .llseek = generic_file_llseek,
+};
+
+/*
+ * This is called during name resolution/lookup to check if the @dentry in
+ * the cache is still valid. the job is handled by vboxsf_inode_revalidate.
+ */
+static int vboxsf_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ if (flags & LOOKUP_RCU)
+ return -ECHILD;
+
+ if (d_really_is_positive(dentry))
+ return vboxsf_inode_revalidate(dentry) == 0;
+ else
+ return vboxsf_stat_dentry(dentry, NULL) == -ENOENT;
+}
+
+const struct dentry_operations vboxsf_dentry_ops = {
+ .d_revalidate = vboxsf_dentry_revalidate
+};
+
+/* iops */
+
+static struct dentry *vboxsf_dir_lookup(struct inode *parent,
+ struct dentry *dentry,
+ unsigned int flags)
+{
+ struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+ struct shfl_fsobjinfo fsinfo;
+ struct inode *inode;
+ int err;
+
+ dentry->d_time = jiffies;
+
+ err = vboxsf_stat_dentry(dentry, &fsinfo);
+ if (err) {
+ inode = (err == -ENOENT) ? NULL : ERR_PTR(err);
+ } else {
+ inode = vboxsf_new_inode(parent->i_sb);
+ if (!IS_ERR(inode))
+ vboxsf_init_inode(sbi, inode, &fsinfo);
+ }
+
+ return d_splice_alias(inode, dentry);
+}
+
+static int vboxsf_dir_instantiate(struct inode *parent, struct dentry *dentry,
+ struct shfl_fsobjinfo *info)
+{
+ struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+ struct vboxsf_inode *sf_i;
+ struct inode *inode;
+
+ inode = vboxsf_new_inode(parent->i_sb);
+ if (IS_ERR(inode))
+ return PTR_ERR(inode);
+
+ sf_i = VBOXSF_I(inode);
+ /* The host may have given us different attr then requested */
+ sf_i->force_restat = 1;
+ vboxsf_init_inode(sbi, inode, info);
+
+ d_instantiate(dentry, inode);
+
+ return 0;
+}
+
+static int vboxsf_dir_create(struct inode *parent, struct dentry *dentry,
+ umode_t mode, int is_dir)
+{
+ struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
+ struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+ struct shfl_createparms params = {};
+ int err;
+
+ params.handle = SHFL_HANDLE_NIL;
+ params.create_flags = SHFL_CF_ACT_CREATE_IF_NEW |
+ SHFL_CF_ACT_FAIL_IF_EXISTS |
+ SHFL_CF_ACCESS_READWRITE |
+ (is_dir ? SHFL_CF_DIRECTORY : 0);
+ params.info.attr.mode = (mode & 0777) |
+ (is_dir ? SHFL_TYPE_DIRECTORY : SHFL_TYPE_FILE);
+ params.info.attr.additional = SHFLFSOBJATTRADD_NOTHING;
+
+ err = vboxsf_create_at_dentry(dentry, ¶ms);
+ if (err)
+ return err;
+
+ if (params.result != SHFL_FILE_CREATED)
+ return -EPERM;
+
+ vboxsf_close(sbi->root, params.handle);
+
+ err = vboxsf_dir_instantiate(parent, dentry, ¶ms.info);
+ if (err)
+ return err;
+
+ /* parent directory access/change time changed */
+ sf_parent_i->force_restat = 1;
+
+ return 0;
+}
+
+static int vboxsf_dir_mkfile(struct inode *parent, struct dentry *dentry,
+ umode_t mode, bool excl)
+{
+ return vboxsf_dir_create(parent, dentry, mode, 0);
+}
+
+static int vboxsf_dir_mkdir(struct inode *parent, struct dentry *dentry,
+ umode_t mode)
+{
+ return vboxsf_dir_create(parent, dentry, mode, 1);
+}
+
+static int vboxsf_dir_unlink(struct inode *parent, struct dentry *dentry)
+{
+ struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+ struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
+ struct inode *inode = d_inode(dentry);
+ struct shfl_string *path;
+ u32 flags;
+ int err;
+
+ if (S_ISDIR(inode->i_mode))
+ flags = SHFL_REMOVE_DIR;
+ else
+ flags = SHFL_REMOVE_FILE;
+
+ if (S_ISLNK(inode->i_mode))
+ flags |= SHFL_REMOVE_SYMLINK;
+
+ path = vboxsf_path_from_dentry(sbi, dentry);
+ if (IS_ERR(path))
+ return PTR_ERR(path);
+
+ err = vboxsf_remove(sbi->root, path, flags);
+ __putname(path);
+ if (err)
+ return err;
+
+ /* parent directory access/change time changed */
+ sf_parent_i->force_restat = 1;
+
+ return 0;
+}
+
+static int vboxsf_dir_rename(struct inode *old_parent,
+ struct dentry *old_dentry,
+ struct inode *new_parent,
+ struct dentry *new_dentry,
+ unsigned int flags)
+{
+ struct vboxsf_sbi *sbi = VBOXSF_SBI(old_parent->i_sb);
+ struct vboxsf_inode *sf_old_parent_i = VBOXSF_I(old_parent);
+ struct vboxsf_inode *sf_new_parent_i = VBOXSF_I(new_parent);
+ u32 shfl_flags = SHFL_RENAME_FILE | SHFL_RENAME_REPLACE_IF_EXISTS;
+ struct shfl_string *old_path, *new_path;
+ int err;
+
+ if (flags)
+ return -EINVAL;
+
+ old_path = vboxsf_path_from_dentry(sbi, old_dentry);
+ if (IS_ERR(old_path))
+ return PTR_ERR(old_path);
+
+ new_path = vboxsf_path_from_dentry(sbi, new_dentry);
+ if (IS_ERR(new_path)) {
+ err = PTR_ERR(new_path);
+ goto err_put_old_path;
+ }
+
+ if (d_inode(old_dentry)->i_mode & S_IFDIR)
+ shfl_flags = 0;
+
+ err = vboxsf_rename(sbi->root, old_path, new_path, shfl_flags);
+ if (err == 0) {
+ /* parent directories access/change time changed */
+ sf_new_parent_i->force_restat = 1;
+ sf_old_parent_i->force_restat = 1;
+ }
+
+ __putname(new_path);
+err_put_old_path:
+ __putname(old_path);
+ return err;
+}
+
+static int vboxsf_dir_symlink(struct inode *parent, struct dentry *dentry,
+ const char *symname)
+{
+ struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
+ struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
+ int symname_size = strlen(symname) + 1;
+ struct shfl_string *path, *ssymname;
+ struct shfl_fsobjinfo info;
+ int err;
+
+ path = vboxsf_path_from_dentry(sbi, dentry);
+ if (IS_ERR(path))
+ return PTR_ERR(path);
+
+ ssymname = kmalloc(SHFLSTRING_HEADER_SIZE + symname_size, GFP_KERNEL);
+ if (!ssymname) {
+ __putname(path);
+ return -ENOMEM;
+ }
+ ssymname->length = symname_size - 1;
+ ssymname->size = symname_size;
+ memcpy(ssymname->string.utf8, symname, symname_size);
+
+ err = vboxsf_symlink(sbi->root, path, ssymname, &info);
+ kfree(ssymname);
+ __putname(path);
+ if (err) {
+ /* -EROFS means symlinks are note support -> -EPERM */
+ return (err == -EROFS) ? -EPERM : err;
+ }
+
+ err = vboxsf_dir_instantiate(parent, dentry, &info);
+ if (err)
+ return err;
+
+ /* parent directory access/change time changed */
+ sf_parent_i->force_restat = 1;
+ return 0;
+}
+
+const struct inode_operations vboxsf_dir_iops = {
+ .lookup = vboxsf_dir_lookup,
+ .create = vboxsf_dir_mkfile,
+ .mkdir = vboxsf_dir_mkdir,
+ .rmdir = vboxsf_dir_unlink,
+ .unlink = vboxsf_dir_unlink,
+ .rename = vboxsf_dir_rename,
+ .symlink = vboxsf_dir_symlink,
+ .getattr = vboxsf_getattr,
+ .setattr = vboxsf_setattr,
+};
