On 03/15/2018 09:13 AM, Misono, Tomohiro wrote:
> This is a preparetion work to allow normal user to call
> "subvolume list/show".
>
> Signed-off-by: Tomohiro Misono <misono.tomohiro@xxxxxxxxxxxxxx>
> ---
> btrfs-list.c | 33 +++++++++++++++++++++++++++++++++
> btrfs-list.h | 1 +
> 2 files changed, 34 insertions(+)
>
> diff --git a/btrfs-list.c b/btrfs-list.c
> index 50e5ce5f..88689a9d 100644
> --- a/btrfs-list.c
> +++ b/btrfs-list.c
> @@ -958,6 +958,39 @@ out:
> return 0;
> }
>
> +/*
> + * Check the permission for tree search ioctl by searching a key
> + * which alwasys exists
> + */
> +int check_perm_for_tree_search(int fd)
> +{
In what this is different from '(getuid() == 0)' ?
Which would be the cases where an error different from EPERM would be returned (other than the filesystem is not a BTRFS one )?
I am not against to this kind of function. However with this implementation is not clear its behavior:
- does it check if the user has enough privileges to perform a BTRFS_IOC_TREE_SEARCH
or
- does it check if BTRFS_IOC_TREE_SEARCH might return some error ?
If the former, I would put this function into utils.[hc] checking only the [e]uid of the user. If the latter the name is confusing...
> + struct btrfs_ioctl_search_args args;
> + struct btrfs_ioctl_search_key *sk = &args.key;
> + int ret;
> +
> + memset(&args, 0, sizeof(args));
> + sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
> + sk->min_objectid = BTRFS_EXTENT_TREE_OBJECTID;
> + sk->max_objectid = BTRFS_EXTENT_TREE_OBJECTID;
> + sk->min_type = BTRFS_ROOT_ITEM_KEY;
> + sk->max_type = BTRFS_ROOT_ITEM_KEY;
> + sk->min_offset = 0;
> + sk->max_offset = (u64)-1;
> + sk->min_transid = 0;
> + sk->max_transid = (u64)-1;
> + sk->nr_items = 1;
> + ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
> +
> + if (!ret)
> + ret = 1;
> + else if (ret < 0 && errno == EPERM)
> + ret = 0;
> + else
> + ret = -errno;
> +
> + return ret;
> +}
> +
> static int list_subvol_search(int fd, struct root_lookup *root_lookup)
> {
> int ret;
> diff --git a/btrfs-list.h b/btrfs-list.h
> index 6e5fc778..6225311d 100644
> --- a/btrfs-list.h
> +++ b/btrfs-list.h
> @@ -176,5 +176,6 @@ char *btrfs_list_path_for_root(int fd, u64 root);
> int btrfs_list_get_path_rootid(int fd, u64 *treeid);
> int btrfs_get_subvol(int fd, struct root_info *the_ri);
> int btrfs_get_toplevel_subvol(int fd, struct root_info *the_ri);
> +int check_perm_for_tree_search(int fd);
>
> #endif
>
--
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
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