Re: [PATCH RFC v10 9/17] ipe: add permissive toggle

[Paul Moore <paul@paul-moore.com>]

On Jun 28, 2023 Fan Wu <wufan@linux.microsoft.com> wrote:
> 
> IPE, like SELinux, supports a permissive mode. This mode allows policy
> authors to test and evaluate IPE policy without it effecting their
> programs. When the mode is changed, a 1404 AUDIT_MAC_STATUS
> be reported.
> 
> This patch adds the following audit records:
> 
>     audit: MAC_STATUS enforcing=0 old_enforcing=1 auid=4294967295
>       ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1
>     audit: MAC_STATUS enforcing=1 old_enforcing=0 auid=4294967295
>       ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1
> 
> The audit record only emit when the value from the user input is
> different from the current enforce value.
> 
> Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com>
> Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
> ---
>  security/ipe/audit.c | 22 ++++++++++++++
>  security/ipe/audit.h |  1 +
>  security/ipe/eval.c  |  9 ++++++
>  security/ipe/eval.h  |  1 +
>  security/ipe/fs.c    | 69 ++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 102 insertions(+)

...

> diff --git a/security/ipe/fs.c b/security/ipe/fs.c
> index 6bd2aa84831b..1761d39e4d04 100644
> --- a/security/ipe/fs.c
> +++ b/security/ipe/fs.c
> @@ -16,6 +16,7 @@ static struct dentry *np __ro_after_init;
>  static struct dentry *root __ro_after_init;
>  struct dentry *policy_root __ro_after_init;
>  static struct dentry *audit_node __ro_after_init;
> +static struct dentry *enforce_node __ro_after_init;
>  
>  /**
>   * setaudit - Write handler for the securityfs node, "ipe/success_audit"
> @@ -68,6 +69,61 @@ static ssize_t getaudit(struct file *f, char __user *data,
>  	return simple_read_from_buffer(data, len, offset, result, 1);
>  }
>  
> +/**
> + * setenforce - Write handler for the securityfs node, "ipe/enforce"
> + * @f: Supplies a file structure representing the securityfs node.
> + * @data: Supplies a buffer passed to the write syscall.
> + * @len: Supplies the length of @data.
> + * @offset: unused.
> + *
> + * Return:
> + * * >0	- Success, Length of buffer written
> + * * <0	- Error
> + */
> +static ssize_t setenforce(struct file *f, const char __user *data,
> +			  size_t len, loff_t *offset)
> +{
> +	int rc = 0;
> +	bool new_value, old_value;
> +
> +	if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
> +		return -EPERM;
> +
> +	old_value = READ_ONCE(enforce);
> +	new_value = old_value;

Why set @new_value equal to @old_value here?

> +	rc = kstrtobool_from_user(data, len, &new_value);
> +	if (rc)
> +		return rc;
> +
> +	if (new_value != old_value) {
> +		ipe_audit_enforce(new_value, old_value);
> +		WRITE_ONCE(enforce, new_value);
> +	}
> +
> +	return len;
> +}

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