Re: [LTP] [PATCH v2 2/8] ima_setup.sh: Allow to load predefined policy

[Mimi Zohar <zohar@linux.ibm.com>]

Hi Petr,

On Fri, 2024-12-13 at 23:20 +0100, Petr Vorel wrote:
[snip]

> --- a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
> +++ b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
> @@ -1,7 +1,7 @@
>  #!/bin/sh
>  # SPDX-License-Identifier: GPL-2.0-or-later
>  # Copyright (c) 2009 IBM Corporation
> -# Copyright (c) 2018-2020 Petr Vorel <pvorel@suse.cz>
> +# Copyright (c) 2018-2024 Petr Vorel <pvorel@suse.cz>
>  # Author: Mimi Zohar <zohar@linux.ibm.com>
>  
>  TST_TESTFUNC="test"
> @@ -72,14 +72,20 @@ require_policy_readable()
>  	fi
>  }
>  
> -require_policy_writable()
> +check_policy_writable()
>  {
> -	local err="IMA policy already loaded and kernel not configured to enable multiple writes to it (need CONFIG_IMA_WRITE_POLICY=y)"
> -
> -	[ -f $IMA_POLICY ] || tst_brk TCONF "$err"
> -	# CONFIG_IMA_READ_POLICY
> +	[ -f $IMA_POLICY ] || return 1
> +	# workaround for kernels < v4.18 without fix
> +	# ffb122de9a60b ("ima: Reflect correct permissions for policy")
>  	echo "" 2> log > $IMA_POLICY
> -	grep -q "Device or resource busy" log && tst_brk TCONF "$err"
> +	grep -q "Device or resource busy" log && return 1
> +	return 0
> +}
> +
> +require_policy_writable()
> +{
> +	check_policy_writable || tst_brk TCONF \
> +		"IMA policy already loaded and kernel not configured to enable multiple writes to it (need CONFIG_IMA_WRITE_POLICY=y)"
>  }
>  
>  check_ima_policy_content()
> @@ -158,6 +164,34 @@ print_ima_config()
>  	tst_res TINFO "/proc/cmdline: $(cat /proc/cmdline)"
>  }
>  
> +load_ima_policy()
> +{
> +	local policy="$(ls $TST_DATAROOT/*.policy 2>/dev/null)"
> +
> +	if [ "$LTP_IMA_LOAD_POLICY" != 1 -a "$policy" -a -f "$policy" ]; then
> +		tst_res TINFO "NOTE: set LTP_IMA_LOAD_POLICY=1 to load policy for this test"
> +		return
> +	fi
> +
> +	if [ -z "$policy" -o ! -f "$policy" ]; then
> +		tst_res TINFO "no policy for this test"
> +		LTP_IMA_LOAD_POLICY=
> +		return
> +	fi
> +
> +	tst_res TINFO "trying to load '$policy' policy:"
> +	cat $policy
> +	if ! check_policy_writable; then
> +		tst_res TINFO "WARNING: IMA policy already loaded and kernel not configured to enable multiple writes to it (need CONFIG_IMA_WRITE_POLICY=y), reboot required"
> +		LTP_IMA_LOAD_POLICY=
> +		return
> +	fi
> +
> +	cat "$policy" 2> log > $IMA_POLICY
> +	if grep -q "Device or resource busy" log; then
> +		tst_brk TBROK "Loading policy failed"
> +	fi

To write to the IMA securityfs policy file, check_policy_writable() used "echo",
while here it's using "cat".  "cat" fails when signed policies are required.
Perhaps add something like:
+
+       if grep -q "write error: Permission denied" log; then
+               tst_brk TBROK "Loading unsigned policy failed"
+       fi

> +}

Mimi


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