Hi
> -----Original Message-----
> From: linux-btrfs-ow...@vger.kernel.org
> [mailto:linux-btrfs-ow...@vger.kernel.org] On Behalf Of Tomohiro Misono
> Sent: Friday, May 11, 2018 3:26 PM
> To: linux-btrfs@vger.kernel.org
> Subject: [PATCH v4 3/3] btrfs: Add unprivileged version of ino_lookup ioctl
>
> Add unprivileged version of ino_lookup ioctl BTRFS_IOC_INO_LOOKUP_USER to
> allow normal users to call "btrfs subvololume list/show"
s/subvololume/subvolume
> etc. in combination with
> BTRFS_IOC_GET_SUBVOL_INFO/BTRFS_IOC_GET_SUBVOL_ROOTREF.
>
> This can be used like BTRFS_IOC_INO_LOOKUP but the argument is different.
> This is because it always searches the fs/file tree
> correspoinding to the fd with which this ioctl is called and also returns the
> name of bottom subvolume.
>
> The main differences from original ino_lookup ioctl are:
> 1. Read + Exec permission will be checked using inode_permission()
> during path construction. -EACCES will be returned in case
> of failure.
> 2. Path construction will be stopped at the inode number which
> corresponds to the fd with which this ioctl is called. If
> constructed path does not exist under fd's inode, -EACCES
> will be returned.
> 3. The name of bottom subvolume is also searched and filled.
>
> Note that the maximum length of path is shorter 256 (BTRFS_VOL_NAME_MAX+1)
> bytes than ino_lookup ioctl because of space of
> subvolume's name.
>
> Signed-off-by: Tomohiro Misono <misono.tomoh...@jp.fujitsu.com>
> ---
> fs/btrfs/ioctl.c | 204
> +++++++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/btrfs.h | 17 ++++
> 2 files changed, 221 insertions(+)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index
> 7988d328aed5..e326a85134f4 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2200,6 +2200,166 @@ static noinline int btrfs_search_path_in_tree(struct
> btrfs_fs_info *info,
> return ret;
> }
>
> +static noinline int btrfs_search_path_in_tree_user(struct inode *inode,
> + struct btrfs_ioctl_ino_lookup_user_args *args) {
> + struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
> + struct super_block *sb = inode->i_sb;
> + struct btrfs_key upper_limit = BTRFS_I(inode)->location;
> + u64 treeid = BTRFS_I(inode)->root->root_key.objectid;
> + u64 dirid = args->dirid;
> +
> + unsigned long item_off;
> + unsigned long item_len;
> + struct btrfs_inode_ref *iref;
> + struct btrfs_root_ref *rref;
> + struct btrfs_root *root;
> + struct btrfs_path *path;
> + struct btrfs_key key, key2;
> + struct extent_buffer *l;
> + struct inode *temp_inode;
> + char *ptr;
> + int slot;
> + int len;
> + int total_len = 0;
> + int ret = -1;
> +
> + path = btrfs_alloc_path();
> + if (!path)
> + return -ENOMEM;
> +
> + /*
> + * If the bottom subvolume does not exist directly under upper_limit,
> + * construct the path in bottomup way.
> + */
> + if (dirid != upper_limit.objectid) {
> + ptr = &args->path[BTRFS_INO_LOOKUP_USER_PATH_MAX - 1];
> +
> + key.objectid = treeid;
> + key.type = BTRFS_ROOT_ITEM_KEY;
> + key.offset = (u64)-1;
> + root = btrfs_read_fs_root_no_name(fs_info, &key);
> + if (IS_ERR(root)) {
> + ret = -ENOENT;
> + goto out;
> + }
> +
> + key.objectid = dirid;
> + key.type = BTRFS_INODE_REF_KEY;
> + key.offset = (u64)-1;
> + while (1) {
> + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
> + if (ret < 0) {
> + goto out;
> + } else if (ret > 0) {
> + ret = btrfs_previous_item(root, path, dirid,
> + BTRFS_INODE_REF_KEY);
> + if (ret < 0) {
> + goto out;
> + } else if (ret > 0) {
> + ret = -ENOENT;
> + goto out;
> + }
> + }
> +
> + l = path->nodes[0];
> + slot = path->slots[0];
> + btrfs_item_key_to_cpu(l, &key, slot);
> +
> + iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);
> + len = btrfs_inode_ref_name_len(l, iref);
> + ptr -= len + 1;
> + total_len += len + 1;
> + if (ptr < args->path) {
> + ret = -ENAMETOOLONG;
> + goto out;
> + }
> +
> + *(ptr + len) = '/';
> + read_extent_buffer(l, ptr,
> + (unsigned long)(iref + 1), len);
> +
> + /* Check the read+exec permission of this directory */
> + ret = btrfs_previous_item(root, path, dirid,
> + BTRFS_INODE_ITEM_KEY);
> + if (ret < 0) {
> + goto out;
> + } else if (ret > 0) {
> + ret = -ENOENT;
> + goto out;
> + }
> +
> + l = path->nodes[0];
> + slot = path->slots[0];
> + btrfs_item_key_to_cpu(l, &key2, slot);
> + if (key2.objectid != dirid) {
> + ret = -ENOENT;
> + goto out;
> + }
> +
> + temp_inode = btrfs_iget(sb, &key2, root, NULL);
> + ret = inode_permission(temp_inode, MAY_READ | MAY_EXEC);
> + iput(temp_inode);
> + if (ret) {
> + ret = -EACCES;
> + goto out;
> + }
> +
> + if (key.offset == upper_limit.objectid)
> + break;
> + if (key.objectid == BTRFS_FIRST_FREE_OBJECTID) {
> + ret = -EACCES;
> + goto out;
> + }
> +
> + btrfs_release_path(path);
> + key.objectid = key.offset;
> + key.offset = (u64)-1;
> + dirid = key.objectid;
> + }
> +
> + memmove(args->path, ptr, total_len);
> + args->path[total_len] = '\0';
> + btrfs_release_path(path);
> + }
> +
> + /* get the bottom subolume's name from ROOT_REF */
> + root = fs_info->tree_root;
> + key.objectid = treeid;
> + key.type = BTRFS_ROOT_REF_KEY;
> + key.offset = args->subvolid;
> + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
> + if (ret < 0) {
> + goto out;
> + } else if (ret > 0) {
> + ret = -ENOENT;
> + goto out;
> + }
> +
> + l = path->nodes[0];
> + slot = path->slots[0];
> + btrfs_item_key_to_cpu(l, &key, slot);
> +
> + item_off = btrfs_item_ptr_offset(l, slot);
> + item_len = btrfs_item_size_nr(l, slot);
> + /* check if dirid in ROOT_REF corresponds to passed dirid */
> + rref = btrfs_item_ptr(l, slot, struct btrfs_root_ref);
> + if (args->dirid != btrfs_root_ref_dirid(l, rref)) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + /* copy subvolume's name */
> + item_off += sizeof(struct btrfs_root_ref);
> + item_len -= sizeof(struct btrfs_root_ref);
> + read_extent_buffer(l, args->name, item_off, item_len);
> + args->name[item_len] = '\0';
> +
> +out:
> + btrfs_free_path(path);
> + return ret;
> +}
> +
> static noinline int btrfs_ioctl_ino_lookup(struct file *file,
> void __user *argp)
> {
> @@ -2242,6 +2402,48 @@ static noinline int btrfs_ioctl_ino_lookup(struct file
> *file,
> return ret;
> }
>
> +/*
> + * User version of ino_lookup ioctl (unprivileged)
> + *
> + * The main differences from original ino_lookup ioctl are:
> + * 1. Read + Exec permission will be checked using inode_permission()
> + * during path construction. -EACCES will be returned in case
> + * of failure.
> + * 2. Path construction will be stopped at the inode number which
> + * corresponds to the fd with which this ioctl is called. If
> + * constructed path does not exist under fd's inode, -EACCES
> + * will be returned.
> + * 3. The name of bottom subvolume is also searched and filled.
> + */
> +static noinline int btrfs_ioctl_ino_lookup_user(struct file *file,
> + void __user *argp)
> +{
> + struct btrfs_ioctl_ino_lookup_user_args *args;
> + struct inode *inode;
> + int ret = 0;
> +
> + args = memdup_user(argp, sizeof(*args));
> + if (IS_ERR(args))
> + return PTR_ERR(args);
> +
> + inode = file_inode(file);
> +
> + if (args->dirid == BTRFS_FIRST_FREE_OBJECTID &&
> + BTRFS_I(inode)->location.objectid != BTRFS_FIRST_FREE_OBJECTID) {
> + /* The subvolume does not exist under fd with which this is called */
> + kfree(args);
> + return -EACCES;
> + }
> +
> + ret = btrfs_search_path_in_tree_user(inode, args);
> +
> + if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
> + ret = -EFAULT;
> +
> + kfree(args);
> + return ret;
> +}
> +
> /* Get the subvolume information in BTRFS_ROOT_ITEM and BTRFS_ROOT_BACKREF
> */ static noinline int
> btrfs_ioctl_get_subvol_info(struct file *file,
> void __user *argp)
> @@ -5605,6 +5807,8 @@ long btrfs_ioctl(struct file *file, unsigned int
> return btrfs_ioctl_get_subvol_info(file, argp);
> case BTRFS_IOC_GET_SUBVOL_ROOTREF:
> return btrfs_ioctl_get_subvol_rootref(file, argp);
> + case BTRFS_IOC_INO_LOOKUP_USER:
> + return btrfs_ioctl_ino_lookup_user(file, argp);
> }
>
> return -ENOTTY;
> diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h index
> 82c88d52d6e6..5f91de93dd5a 100644
> --- a/include/uapi/linux/btrfs.h
> +++ b/include/uapi/linux/btrfs.h
> @@ -422,6 +422,21 @@ struct btrfs_ioctl_ino_lookup_args {
> char name[BTRFS_INO_LOOKUP_PATH_MAX];
> };
>
> +#define BTRFS_INO_LOOKUP_USER_PATH_MAX (4080-BTRFS_VOL_NAME_MAX-1)
> +struct btrfs_ioctl_ino_lookup_user_args {
> + /* in, inode number containing the subvolume of 'subvolid' */
> + __u64 dirid;
> + /* in */
> + __u64 subvolid;
> + /* out, name of the subvolume of 'subvolid' */
> + char name[BTRFS_VOL_NAME_MAX + 1];
> + /*
> + * out, constructed path from the directory with which
> + * the ioctl is called to dirid
> + */
> + char path[BTRFS_INO_LOOKUP_USER_PATH_MAX];
> +};
> +
> /* Search criteria for the btrfs SEARCH ioctl family. */ struct
> btrfs_ioctl_search_key {
> /*
> @@ -910,5 +925,7 @@ enum btrfs_err_code {
> struct btrfs_ioctl_get_subvol_info_args)
> #define BTRFS_IOC_GET_SUBVOL_ROOTREF
> _IOWR(BTRFS_IOCTL_MAGIC, 61, \
> struct btrfs_ioctl_get_subvol_rootref_args)
> +#define BTRFS_IOC_INO_LOOKUP_USER _IOWR(BTRFS_IOCTL_MAGIC, 62, \
> + struct btrfs_ioctl_ino_lookup_user_args)
>
> #endif /* _UAPI_LINUX_BTRFS_H */
> --
Seems good to me.
Reviewed-by: Gu Jinxiang <g...@cn.fujitsu.com>
> 2.14.3
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majord...@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
N�Р骒r��y����b�X�肚�v�^�)藓{.n�+�伐�{�n谶�)��骅w* jg�报 �����茛j/�赇z罐���2���ㄨ��&�)摺�a囤�� �G���h��j:+v���w��佶
