linux-kernel - Re: [PATCH 5.10 083/102] scsi: iscsi: Restrict sessions and handles to admin capabilities

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Date:   Fri, 5 Mar 2021 23:42:26 +0100
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Adam Nichols <adam@...mm-co.com>,
        Chris Leech <cleech@...hat.com>,
        Mike Christie <michael.christie@...cle.com>,
        Lee Duncan <lduncan@...e.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Subject: Re: [PATCH 5.10 083/102] scsi: iscsi: Restrict sessions and handles
 to admin capabilities

Hi!

> From: Lee Duncan <lduncan@...e.com>
> 
> commit 688e8128b7a92df982709a4137ea4588d16f24aa upstream.
> 
> Protect the iSCSI transport handle, available in sysfs, by requiring
> CAP_SYS_ADMIN to read it. Also protect the netlink socket by restricting
> reception of messages to ones sent with CAP_SYS_ADMIN. This disables
> normal users from being able to end arbitrary iSCSI sessions.

Should not normal filesystem permissions be used?

> +++ b/drivers/scsi/scsi_transport_iscsi.c
> @@ -132,6 +132,9 @@ show_transport_handle(struct device *dev
>  		      char *buf)
>  {
>  	struct iscsi_internal *priv = dev_to_iscsi_internal(dev);
> +
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EACCES;
>  	return sprintf(buf, "%llu\n", (unsigned long long)iscsi_handle(priv->iscsi_transport));
>  }
>  static DEVICE_ATTR(handle, S_IRUGO, show_transport_handle, NULL);

AFAICT we make the file 0444 (world readable) and then fail the read
with capability check. If the file is not supposed to be
world-readable, it should have 0400 permissions, right?

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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