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

[Konstantin Meskhidze (A)]

6/27/2023 7:14 PM, Mickaël Salaün пишет:
> 
> On 15/05/2023 18:13, 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 at digikod.net>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze at huawei.com>
>> ---
>> 
>> Changes since v10:
>> * Removes "packed" attribute.
>> * Applies Mickaёl's patch with some refactoring.
>> * Deletes get_port() and check_addrlen() helpers.
>> * Refactors check_socket_access() by squashing get_port() and
>> check_addrlen() helpers into it.
>> * Fixes commit message.
>> 
>> Changes since v9:
>> * Changes UAPI port field to __u64.
>> * Moves shared code into check_socket_access().
>> * Adds get_raw_handled_net_accesses() and
>> get_current_net_domain() helpers.
>> * Minor fixes.
>> 
>> Changes since v8:
>> * Squashes commits.
>> * Refactors commit message.
>> * Changes UAPI port field to __be16.
>> * Changes logic of bind/connect hooks with AF_UNSPEC families.
>> * Adds address length checking.
>> * Minor fixes.
>> 
>> Changes since v7:
>> * Squashes commits.
>> * Increments ABI version to 4.
>> * Refactors commit message.
>> * Minor fixes.
>> 
>> Changes since v6:
>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
>>    because it OR values.
>> * Makes landlock_add_net_access_mask() more resilient incorrect values.
>> * Refactors landlock_get_net_access_mask().
>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
>>    LANDLOCK_NUM_ACCESS_FS as value.
>> * Updates access_masks_t to u32 to support network access actions.
>> * Refactors landlock internal functions to support network actions with
>>    landlock_key/key_type/id types.
>> 
>> Changes since v5:
>> * Gets rid of partial revert from landlock_add_rule
>> syscall.
>> * Formats code with clang-format-14.
>> 
>> Changes since v4:
>> * Refactors landlock_create_ruleset() - splits ruleset and
>> masks checks.
>> * Refactors landlock_create_ruleset() and landlock mask
>> setters/getters to support two rule types.
>> * Refactors landlock_add_rule syscall add_rule_path_beneath
>> function by factoring out get_ruleset_from_fd() and
>> landlock_put_ruleset().
>> 
>> Changes since v3:
>> * Splits commit.
>> * Adds network rule support for internal landlock functions.
>> * Adds set_mask and get_mask for network.
>> * Adds rb_root root_net_port.
>> 
>> ---
>>   include/uapi/linux/landlock.h                |  48 +++++
>>   security/landlock/Kconfig                    |   1 +
>>   security/landlock/Makefile                   |   2 +
>>   security/landlock/limits.h                   |   6 +-
>>   security/landlock/net.c                      | 174 +++++++++++++++++++
>>   security/landlock/net.h                      |  26 +++
>>   security/landlock/ruleset.c                  |  52 +++++-
>>   security/landlock/ruleset.h                  |  63 +++++--
>>   security/landlock/setup.c                    |   2 +
>>   security/landlock/syscalls.c                 |  72 +++++++-
>>   tools/testing/selftests/landlock/base_test.c |   2 +-
>>   11 files changed, 425 insertions(+), 23 deletions(-)
>>   create mode 100644 security/landlock/net.c
>>   create mode 100644 security/landlock/net.h
>> 
>> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
>> index 81d09ef9aa50..93794759dad4 100644
>> --- a/include/uapi/linux/landlock.h
>> +++ b/include/uapi/linux/landlock.h
>> @@ -31,6 +31,13 @@ struct landlock_ruleset_attr {
>>   	 * this access right.
>>   	 */
>>   	__u64 handled_access_fs;
>> +
>> +	/**
>> +	 * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
>> +	 * that is handled by this ruleset and should then be forbidden if no
>> +	 * rule explicitly allow them.
>> +	 */
>> +	__u64 handled_access_net;
>>   };
>> 
>>   /*
>> @@ -54,6 +61,11 @@ enum landlock_rule_type {
>>   	 * landlock_path_beneath_attr .
>>   	 */
>>   	LANDLOCK_RULE_PATH_BENEATH = 1,
>> +	/**
>> +	 * @LANDLOCK_RULE_NET_SERVICE: Type of a &struct
>> +	 * landlock_net_service_attr .
>> +	 */
>> +	LANDLOCK_RULE_NET_SERVICE = 2,
>>   };
>> 
>>   /**
>> @@ -79,6 +91,23 @@ struct landlock_path_beneath_attr {
>>   	 */
>>   } __attribute__((packed));
>> 
>> +/**
>> + * struct landlock_net_service_attr - TCP subnet definition
>> + *
>> + * Argument of sys_landlock_add_rule().
>> + */
>> +struct landlock_net_service_attr {
>> +	/**
>> +	 * @allowed_access: Bitmask of allowed access network for services
>> +	 * (cf. `Network flags`_).
>> +	 */
>> +	__u64 allowed_access;
>> +	/**
>> +	 * @port: Network port.
>> +	 */
>> +	__u64 port;
>> +};
> 
> The "net service" name reflects the semantic but it doesn't fit well
> with the data type. It works with TCP, UDP and other protocols such as
> VSOCK, but not unix sockets. I think it makes more sense to rename
> LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT and
> landlock_net_service_attr to landlock_net_port_attr. Please be careful
> with the documentation, non-kernel code, and comments as well.
> 
> In the future, we could add a landlock_net_path_attr to identify a unix
> abstract path, which would also be a network service, but it would not
> accept the TCP access rights.
> 
> The access right names (LANDLOCK_ACCESS_NET_{BIND,CONNECT}_TCP) are
> still good.
> 
   Ok. "net service" will be renamed.
   Thanks.
> 
> I'm still improving tests, so you might wait a bit before renaming the
> related files.
> .