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Date:   Wed, 29 Jan 2020 08:18:16 +1100 (AEDT)
From:   James Morris <jmorris@namei.org>
To:     Alexey Budankov <alexey.budankov@linux.intel.com>
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Subject: Re: [PATCH v6 10/10] drivers/oprofile: open access for CAP_PERFMON
 privileged process
In-Reply-To: <eff5e211-7114-f854-f53f-08491f9dcc26@linux.intel.com>
Message-ID: <alpine.LRH.2.21.2001290818090.2204@namei.org>
References: <74d524ab-ac11-a7b8-1052-eba10f117e09@linux.intel.com> <eff5e211-7114-f854-f53f-08491f9dcc26@linux.intel.com>
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On Tue, 28 Jan 2020, Alexey Budankov wrote:

> 
> Open access to monitoring for CAP_PERFMON privileged process. Providing
> the access under CAP_PERFMON capability singly, without the rest of
> CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials and
> makes operation more secure.
> 
> CAP_PERFMON implements the principal of least privilege for performance
> monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39 principle
> of least privilege: A security design principle that states that a process
> or program be granted only those privileges (e.g., capabilities) necessary
> to accomplish its legitimate function, and only for the time that such
> privileges are actually required)
> 
> For backward compatibility reasons access to the monitoring remains open
> for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for secure
> monitoring is discouraged with respect to CAP_PERFMON capability.
> 
> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
> ---
>  drivers/oprofile/event_buffer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)


Acked-by: James Morris <jamorris@linux.microsoft.com>

> 
> diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c
> index 12ea4a4ad607..6c9edc8bbc95 100644
> --- a/drivers/oprofile/event_buffer.c
> +++ b/drivers/oprofile/event_buffer.c
> @@ -113,7 +113,7 @@ static int event_buffer_open(struct inode *inode, struct file *file)
>  {
>  	int err = -EPERM;
>  
> -	if (!capable(CAP_SYS_ADMIN))
> +	if (!perfmon_capable())
>  		return -EPERM;
>  
>  	if (test_and_set_bit_lock(0, &buffer_opened))
> 

-- 
James Morris
<jmorris@namei.org>