netdev - Re: [PATCH v11 08/12] landlock: Add network rules and TCP hooks support

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Date: Thu, 3 Aug 2023 17:13:33 +0300
From: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
To: Mickaël Salaün <mic@...ikod.net>
CC: <willemdebruijn.kernel@...il.com>, <gnoack3000@...il.com>,
	<linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
	<netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>,
	<artem.kuzin@...wei.com>
Subject: Re: [PATCH v11 08/12] landlock: Add network rules and TCP hooks
 support



8/3/2023 5:12 PM, Mickaël Salaün пишет:
> On Tue, May 16, 2023 at 12:13:35AM +0800, Konstantin Meskhidze wrote:
>> This commit adds network rules support in the ruleset management
>> helpers and the landlock_create_ruleset syscall.
>> Refactor user space API to support network actions. Add new network
>> access flags, network rule and network attributes. Increment Landlock
>> ABI version. Expand access_masks_t to u32 to be sure network access
>> rights can be stored. Implement socket_bind() and socket_connect()
>> LSM hooks, which enables to restrict TCP socket binding and connection
>> to specific ports.
>> 
>> Co-developed-by: Mickaël Salaün <mic@...ikod.net>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>> ---
> 
> [...]
> 
>> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
>> index 8a54e87dbb17..5cb0a1bc6ec0 100644
>> --- a/security/landlock/syscalls.c
>> +++ b/security/landlock/syscalls.c
> 
> [...]
> 
>> +static int add_rule_net_service(struct landlock_ruleset *ruleset,
>> +				const void __user *const rule_attr)
>> +{
>> +#if IS_ENABLED(CONFIG_INET)
> 
> We should define two add_rule_net_service() functions according to
> IS_ENABLED(CONFIG_INET) instead of changing the body of the only
> function.  The second function would only return -EAFNOSUPPORT.  This
> cosmetic change would make the code cleaner.

   Ok. Got it.
> 
> 
>> +	struct landlock_net_service_attr net_service_attr;
>> +	int res;
>> +	access_mask_t mask;
>> +
>> +	/* Copies raw user space buffer, only one type for now. */
>> +	res = copy_from_user(&net_service_attr, rule_attr,
>> +			     sizeof(net_service_attr));
>> +	if (res)
>> +		return -EFAULT;
>> +
>> +	/*
>> +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> +	 * are ignored by network actions.
>> +	 */
>> +	if (!net_service_attr.allowed_access)
>> +		return -ENOMSG;
>> +
>> +	/*
>> +	 * Checks that allowed_access matches the @ruleset constraints
>> +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> +	 */
>> +	mask = landlock_get_net_access_mask(ruleset, 0);
>> +	if ((net_service_attr.allowed_access | mask) != mask)
>> +		return -EINVAL;
>> +
>> +	/* Denies inserting a rule with port 0 or higher than 65535. */
>> +	if ((net_service_attr.port == 0) || (net_service_attr.port > U16_MAX))
>> +		return -EINVAL;
>> +
>> +	/* Imports the new rule. */
>> +	return landlock_append_net_rule(ruleset, net_service_attr.port,
>> +					net_service_attr.allowed_access);
>> +#else /* IS_ENABLED(CONFIG_INET) */
>> +	return -EAFNOSUPPORT;
>> +#endif /* IS_ENABLED(CONFIG_INET) */
>> +}
> .