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Subject: Re: [PATCH v3] scsi: require CAP_SYS_ADMIN to write to procfs
 interface
To:     "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>
Cc:     linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        containers@lists.linux-foundation.org,
        Valentin Rothberg <vrothberg@suse.com>, cyphar@cyphar.com,
        stable@vger.kernel.org, "Eric W. Biederman" <ebiederm@xmission.com>
References: <20171105025635.10843-1-asarai@suse.de>
From:   Aleksa Sarai <asarai@suse.de>
Message-ID: <b3bcff37-d77d-4dc6-ba83-7dddcb51a703@suse.de>
Date:   Sun, 5 Nov 2017 15:02:10 +1100
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On 11/05/2017 01:56 PM, Aleksa Sarai wrote:
> Previously, the only capability effectively required to operate on the
> /proc/scsi interface was CAP_DAC_OVERRIDE (or for some other files,
> having an fsuid of GLOBAL_ROOT_UID was enough). This means that
> semi-privileged processes could interfere with core components of a
> system (such as causing a DoS by removing the underlying SCSI device of
> the host's / mount).

An alternative to this patch would be to make the open(2) call fail, if 
you try to open it write-only or read-write. Not sure which would be 
preferred (should it be possible to pass /proc/scsi/scsi to a 
semi-privileged process to write to?).

-- 
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
https://www.cyphar.com/

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