linux-kernel - Re: [PATCH RFC 4/6] fhandle: pull CAP_DAC_READ_SEARCH check into may_decode

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Message-ID: <20241202160100.sswfmbxiah2sglsc@quack3>
Date: Mon, 2 Dec 2024 17:01:00 +0100
From: Jan Kara <jack@...e.cz>
To: Christian Brauner <brauner@...nel.org>
Cc: Erin Shepherd <erin.shepherd@....eu>,
	Amir Goldstein <amir73il@...il.com>,
	Jeff Layton <jlayton@...nel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
	Chuck Lever <chuck.lever@...cle.com>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org
Subject: Re: [PATCH RFC 4/6] fhandle: pull CAP_DAC_READ_SEARCH check into
 may_decode_fh()

On Fri 29-11-24 14:38:03, Christian Brauner wrote:
> There's no point in keeping it outside of that helper. This way we have
> all the permission pieces in one place.
> 
> Signed-off-by: Christian Brauner <brauner@...nel.org>

Nice. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/fhandle.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/fhandle.c b/fs/fhandle.c
> index c00d88fb14e16654b5cbbb71760c0478eac20384..031ad5592a0beabcc299436f037ad5fe626332e6 100644
> --- a/fs/fhandle.c
> +++ b/fs/fhandle.c
> @@ -298,6 +298,9 @@ static inline bool may_decode_fh(struct handle_to_path_ctx *ctx,
>  {
>  	struct path *root = &ctx->root;
>  
> +	if (capable(CAP_DAC_READ_SEARCH))
> +		return true;
> +
>  	/*
>  	 * Restrict to O_DIRECTORY to provide a deterministic API that avoids a
>  	 * confusing api in the face of disconnected non-dir dentries.
> @@ -337,7 +340,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
>  	if (retval)
>  		goto out_err;
>  
> -	if (!capable(CAP_DAC_READ_SEARCH) && !may_decode_fh(&ctx, o_flags)) {
> +	if (!may_decode_fh(&ctx, o_flags)) {
>  		retval = -EPERM;
>  		goto out_path;
>  	}
> 
> -- 
> 2.45.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR