[PATCH] mkfs.ubifs: fix xattr scanning for builds with selinux support

[Zhihao Cheng]

在 2023/12/15 19:48, David Oberhollenzer 写道:
> mkfs.uibfs can add Selinux xattrs from a labeling file using
> libselinux to parse it. The commit that added this feature simply
> introduced a separate function, inode_add_selinux_xattr, which is
> called instead of inode_add_xattr. If no --selinux argument is
> specified for mkfs.ubifs, this is a no-op.
>
> The problem is, that this breaks xattr scanning for any build with
> Selinux enabled. The Selinux version is always called and it does
> not scan for xattrs on the filesystem, or dispatch to the original.
>
> This commit fixes the xattr scanning behavior. We unconditionally call
> both functions (they each have no-op implementations if the feature
> is missing) and in the regular xattr scanning code, we skip selinux
> attributes, if the --selinux option was given.
>
> Fixes: f1feccec5ad8 ("mkfs.ubifs: Implement selinux labelling support")
>
> Signed-off-by: David Oberhollenzer <goliath at infraroot.at>
> ---
>   ubifs-utils/mkfs.ubifs/mkfs.ubifs.c | 22 ++++++++++++++--------
>   1 file changed, 14 insertions(+), 8 deletions(-)

Reviewed-by: Zhihao Cheng <chengzhihao1 at huawei.com>

>
> diff --git a/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c b/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c
> index 15e6bdc..8f8d40b 100644
> --- a/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c
> +++ b/ubifs-utils/mkfs.ubifs/mkfs.ubifs.c
> @@ -56,7 +56,6 @@
>   #ifdef WITH_SELINUX
>   #define XATTR_NAME_SELINUX "security.selinux"
>   static struct selabel_handle *sehnd;
> -static char *secontext;
>   #endif
>   
>   /**
> @@ -1389,6 +1388,15 @@ static int inode_add_xattr(struct ubifs_ino_node *host_ino,
>   			continue;
>   		}
>   
> +#ifdef WITH_SELINUX
> +		/*
> +		  Ignore selinux attributes if we have a label file, they are
> +		  instead provided by inode_add_selinux_xattr.
> +		 */
> +		if (!strcmp(name, XATTR_NAME_SELINUX) && context && sehnd)
> +			continue;
> +#endif
> +
>   		ret = add_xattr(host_ino, st, inum, name, attrbuf, attrsize);
>   		if (ret < 0)
>   			goto out_free;
> @@ -1413,12 +1421,10 @@ static int inode_add_selinux_xattr(struct ubifs_ino_node *host_ino,
>   	char *sepath = NULL;
>   	char *name;
>   	unsigned int con_size;
> +	char *secontext;
>   
> -	if (!context || !sehnd) {
> -		secontext = NULL;
> -		con_size = 0;
> +	if (!context || !sehnd)
>   		return 0;
> -	}
>   
>   	if (path_name[strlen(root)] == '/')
>   		sepath = strdup(&path_name[strlen(root)]);
> @@ -1595,11 +1601,11 @@ static int add_inode(struct stat *st, ino_t inum, void *data,
>   	len = UBIFS_INO_NODE_SZ + data_len;
>   
>   	if (xattr_path) {
> -#ifdef WITH_SELINUX
>   		ret = inode_add_selinux_xattr(ino, xattr_path, st, inum);
> -#else
> +		if (ret < 0)
> +			return ret;
> +
>   		ret = inode_add_xattr(ino, xattr_path, st, inum);
> -#endif
>   		if (ret < 0)
>   			return ret;
>   	}