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To:     Paul Moore <paul@paul-moore.com>,
        linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
        linux-audit@redhat.com, io-uring@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        Kumar Kartikeya Dwivedi <memxor@gmail.com>,
        Jens Axboe <axboe@kernel.dk>,
        Alexander Viro <viro@zeniv.linux.org.uk>
References: <162163367115.8379.8459012634106035341.stgit@sifl>
 <162163382536.8379.3124023175473604584.stgit@sifl>
From:   Stefan Metzmacher <metze@samba.org>
Subject: Re: [RFC PATCH 7/9] lsm,io_uring: add LSM hooks to io_uring
Message-ID: <00bede98-1bea-e3bc-b0a6-f038dc75c08d@samba.org>
Date:   Wed, 26 May 2021 16:48:23 +0200
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List-ID: <linux-security-module.vger.kernel.org>

Hi Paul,

>  #define CREATE_TRACE_POINTS
>  #include <trace/events/io_uring.h>
> @@ -6537,6 +6538,11 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
>  		if (!req->work.creds)
>  			return -EINVAL;
>  		get_cred(req->work.creds);
> +		ret = security_uring_override_creds(req->work.creds);
> +		if (ret) {
> +			put_cred(req->work.creds);
> +			return ret;
> +		}

Why are you calling this per requests, shouldn't this be done in
io_register_personality()?

I'm also not sure if this really gains anything as io_register_personality()
only captures the value of get_current_cred(), so the process already has changed to
the credentials (at least once for the io_uring_register(IORING_REGISTER_PERSONALITY)
call).

metze