Re: [PATCH v2] vfs: parse sloppy mount option in correct order

[Jeff Layton <jlayton@kernel.org>]

On Thu, 2022-02-10 at 10:44 +0100, Roberto Bergantinos Corpas wrote:
> With addition of fs_context support, options string is parsed
> sequentially, if 'sloppy' option is not leftmost one, we may
> return ENOPARAM to userland if a non-valid option preceeds sloopy
> and mount will fail :
> 
> host# mount -o quota,sloppy 172.23.1.225:/share /mnt
> mount.nfs: an incorrect mount option was specified
> host# mount -o sloppy,quota 172.23.1.225:/share /mnt
> host#
> 
> This patch correct that behaviour so that sloppy takes precedence
> if specified anywhere on the string
> 
> Signed-off-by: Roberto Bergantinos Corpas <rbergant@redhat.com>
> ---
>  fs/cifs/fs_context.c       |  4 ++--
>  fs/cifs/fs_context.h       |  1 -
>  fs/fs_context.c            | 14 ++++++++++++--
>  fs/nfs/fs_context.c        |  4 ++--
>  fs/nfs/internal.h          |  1 -
>  include/linux/fs_context.h |  2 ++
>  6 files changed, 18 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
> index 7ec35f3f0a5f..5a8c074df74a 100644
> --- a/fs/cifs/fs_context.c
> +++ b/fs/cifs/fs_context.c
> @@ -866,7 +866,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
>  	if (!skip_parsing) {
>  		opt = fs_parse(fc, smb3_fs_parameters, param, &result);
>  		if (opt < 0)
> -			return ctx->sloppy ? 1 : opt;
> +			return fc->sloppy ? 1 : opt;
>  	}
>  
>  	switch (opt) {
> @@ -1412,7 +1412,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
>  		ctx->multiuser = true;
>  		break;
>  	case Opt_sloppy:
> -		ctx->sloppy = true;
> +		fc->sloppy = true;
>  		break;
>  	case Opt_nosharesock:
>  		ctx->nosharesock = true;
> diff --git a/fs/cifs/fs_context.h b/fs/cifs/fs_context.h
> index e54090d9ef36..52a67a96fb67 100644
> --- a/fs/cifs/fs_context.h
> +++ b/fs/cifs/fs_context.h
> @@ -155,7 +155,6 @@ struct smb3_fs_context {
>  	bool uid_specified;
>  	bool cruid_specified;
>  	bool gid_specified;
> -	bool sloppy;
>  	bool got_ip;
>  	bool got_version;
>  	bool got_rsize;
> diff --git a/fs/fs_context.c b/fs/fs_context.c
> index 24ce12f0db32..2f9284e53589 100644
> --- a/fs/fs_context.c
> +++ b/fs/fs_context.c
> @@ -155,8 +155,15 @@ int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param)
>  	if (ret != -ENOPARAM)
>  		return ret;
>  
> -	return invalf(fc, "%s: Unknown parameter '%s'",
> -		      fc->fs_type->name, param->key);
> +	/* We got an invalid parameter, but sloppy may have been specified
> +	 * later on param string.
> +	 * Let's wait to process whole params to return EINVAL.
> +	 */
> +
> +	fc->param_inval = true;
> +	errorf(fc, "%s: Unknown parameter '%s'", fc->fs_type->name, param->key);
> +
> +	return 0;
>  }
>  EXPORT_SYMBOL(vfs_parse_fs_param);
>  
> @@ -227,6 +234,9 @@ int generic_parse_monolithic(struct fs_context *fc, void *data)
>  		}
>  	}
>  
> +	if (!fc->sloppy && fc->param_inval)
> +		ret = -EINVAL;
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL(generic_parse_monolithic);
> diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
> index ea17fa1f31ec..c9ff68e17b68 100644
> --- a/fs/nfs/fs_context.c
> +++ b/fs/nfs/fs_context.c
> @@ -482,7 +482,7 @@ static int nfs_fs_context_parse_param(struct fs_context *fc,
>  
>  	opt = fs_parse(fc, nfs_fs_parameters, param, &result);
>  	if (opt < 0)
> -		return ctx->sloppy ? 1 : opt;
> +		return fc->sloppy ? 1 : opt;
>  
>  	if (fc->security)
>  		ctx->has_sec_mnt_opts = 1;
> @@ -837,7 +837,7 @@ static int nfs_fs_context_parse_param(struct fs_context *fc,
>  		 * Special options
>  		 */
>  	case Opt_sloppy:
> -		ctx->sloppy = true;
> +		fc->sloppy = true;
>  		dfprintk(MOUNT, "NFS:   relaxing parsing rules\n");
>  		break;
>  	}
> diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> index 12f6acb483bb..9febdc95b4d0 100644
> --- a/fs/nfs/internal.h
> +++ b/fs/nfs/internal.h
> @@ -80,7 +80,6 @@ struct nfs_fs_context {
>  	bool			internal;
>  	bool			skip_reconfig_option_check;
>  	bool			need_mount;
> -	bool			sloppy;
>  	unsigned int		flags;		/* NFS{,4}_MOUNT_* flags */
>  	unsigned int		rsize, wsize;
>  	unsigned int		timeo, retrans;
> diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
> index 13fa6f3df8e4..06a4b72a0f98 100644
> --- a/include/linux/fs_context.h
> +++ b/include/linux/fs_context.h
> @@ -110,6 +110,8 @@ struct fs_context {
>  	bool			need_free:1;	/* Need to call ops->free() */
>  	bool			global:1;	/* Goes into &init_user_ns */
>  	bool			oldapi:1;	/* Coming from mount(2) */
> +	bool                    sloppy:1;       /* If fs support it and was specified */
> +	bool                    param_inval:1;  /* If set, check sloppy value */
>  };
>  
>  struct fs_context_operations {

This looks like it will do the right thing. We definitely _don't_ want
order-dependent option parsing.

Reviewed-by: Jeff Layton <jlayton@kernel.org>