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Date: Mon, 6 Mar 2023 10:52:37 +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 v9 06/12] landlock: Refactor _unmask_layers() and
_init_layer_masks()
2/21/2023 9:07 PM, Mickaël Salaün пишет:
> It's not "_unmask_layers() and _init_layer_masks()": there is no "_"
> prefixes.
> Using "landlock_unmask_layers()" in the subject would be too long, so
> you can replace it with "landlock: Refactor layer helpers".
> For consistency, you can change the previous patch's subject to
> "landlock: Move and rename layer helpers"
>
> Anyway, please send a new patch series. Most of the kernel code should
> be good and I could then push it to -next for testing while reviewing
> the last parts.
Hi, Mickaël. I was on a short vacation. Sorry for late reply.
I will reply your review and send a new patch ASAP.
Regards,
Konstantin
>
>
> On 16/01/2023 09:58, Konstantin Meskhidze wrote:
>> Add new key_type argument to the landlock_init_layer_masks() helper.
>> Add a masks_array_size argument to the landlock_unmask_layers() helper.
>> These modifications support implementing new rule types in the next
>> Landlock versions.
>>
>> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>> ---
>>
>> Changes since v8:
>> * None.
>>
>> Changes since v7:
>> * Refactors commit message, adds a co-developer.
>> * Minor fixes.
>>
>> Changes since v6:
>> * Removes masks_size attribute from init_layer_masks().
>> * Refactors init_layer_masks() with new landlock_key_type.
>>
>> Changes since v5:
>> * Splits commit.
>> * Formats code with clang-format-14.
>>
>> Changes since v4:
>> * Refactors init_layer_masks(), get_handled_accesses()
>> and unmask_layers() functions to support multiple rule types.
>> * Refactors landlock_get_fs_access_mask() function with
>> LANDLOCK_MASK_ACCESS_FS mask.
>>
>> Changes since v3:
>> * Splits commit.
>> * Refactors landlock_unmask_layers functions.
>>
>> ---
>> security/landlock/fs.c | 43 ++++++++++++++++--------------
>> security/landlock/ruleset.c | 52 ++++++++++++++++++++++++++-----------
>> security/landlock/ruleset.h | 17 ++++++------
>> 3 files changed, 70 insertions(+), 42 deletions(-)
>>
>> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
>> index 73a7399f93ba..a73dbd3f9ddb 100644
>> --- a/security/landlock/fs.c
>> +++ b/security/landlock/fs.c
>> @@ -441,20 +441,22 @@ static bool is_access_to_paths_allowed(
>> }
>>
>> if (unlikely(dentry_child1)) {
>> - landlock_unmask_layers(find_rule(domain, dentry_child1),
>> - landlock_init_layer_masks(
>> - domain, LANDLOCK_MASK_ACCESS_FS,
>> - &_layer_masks_child1),
>> - &_layer_masks_child1);
>> + landlock_unmask_layers(
>> + find_rule(domain, dentry_child1),
>> + landlock_init_layer_masks(
>> + domain, LANDLOCK_MASK_ACCESS_FS,
>> + &_layer_masks_child1, LANDLOCK_KEY_INODE),
>> + &_layer_masks_child1, ARRAY_SIZE(_layer_masks_child1));
>> layer_masks_child1 = &_layer_masks_child1;
>> child1_is_directory = d_is_dir(dentry_child1);
>> }
>> if (unlikely(dentry_child2)) {
>> - landlock_unmask_layers(find_rule(domain, dentry_child2),
>> - landlock_init_layer_masks(
>> - domain, LANDLOCK_MASK_ACCESS_FS,
>> - &_layer_masks_child2),
>> - &_layer_masks_child2);
>> + landlock_unmask_layers(
>> + find_rule(domain, dentry_child2),
>> + landlock_init_layer_masks(
>> + domain, LANDLOCK_MASK_ACCESS_FS,
>> + &_layer_masks_child2, LANDLOCK_KEY_INODE),
>> + &_layer_masks_child2, ARRAY_SIZE(_layer_masks_child2));
>> layer_masks_child2 = &_layer_masks_child2;
>> child2_is_directory = d_is_dir(dentry_child2);
>> }
>> @@ -507,14 +509,15 @@ static bool is_access_to_paths_allowed(
>>
>> rule = find_rule(domain, walker_path.dentry);
>> allowed_parent1 = landlock_unmask_layers(
>> - rule, access_masked_parent1, layer_masks_parent1);
>> + rule, access_masked_parent1, layer_masks_parent1,
>> + ARRAY_SIZE(*layer_masks_parent1));
>> allowed_parent2 = landlock_unmask_layers(
>> - rule, access_masked_parent2, layer_masks_parent2);
>> + rule, access_masked_parent2, layer_masks_parent2,
>> + ARRAY_SIZE(*layer_masks_parent2));
>>
>> /* Stops when a rule from each layer grants access. */
>> if (allowed_parent1 && allowed_parent2)
>> break;
>> -
>> jump_up:
>> if (walker_path.dentry == walker_path.mnt->mnt_root) {
>> if (follow_up(&walker_path)) {
>> @@ -553,8 +556,8 @@ static int check_access_path(const struct landlock_ruleset *const domain,
>> {
>> layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
>>
>> - access_request =
>> - landlock_init_layer_masks(domain, access_request, &layer_masks);
>> + access_request = landlock_init_layer_masks(
>> + domain, access_request, &layer_masks, LANDLOCK_KEY_INODE);
>> if (is_access_to_paths_allowed(domain, path, access_request,
>> &layer_masks, NULL, 0, NULL, NULL))
>> return 0;
>> @@ -640,7 +643,8 @@ static bool collect_domain_accesses(
>> return true;
>>
>> access_dom = landlock_init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> - layer_masks_dom);
>> + layer_masks_dom,
>> + LANDLOCK_KEY_INODE);
>>
>> dget(dir);
>> while (true) {
>> @@ -648,7 +652,8 @@ static bool collect_domain_accesses(
>>
>> /* Gets all layers allowing all domain accesses. */
>> if (landlock_unmask_layers(find_rule(domain, dir), access_dom,
>> - layer_masks_dom)) {
>> + layer_masks_dom,
>> + ARRAY_SIZE(*layer_masks_dom))) {
>> /*
>> * Stops when all handled accesses are allowed by at
>> * least one rule in each layer.
>> @@ -763,7 +768,7 @@ static int current_check_refer_path(struct dentry *const old_dentry,
>> */
>> access_request_parent1 = landlock_init_layer_masks(
>> dom, access_request_parent1 | access_request_parent2,
>> - &layer_masks_parent1);
>> + &layer_masks_parent1, LANDLOCK_KEY_INODE);
>> if (is_access_to_paths_allowed(
>> dom, new_dir, access_request_parent1,
>> &layer_masks_parent1, NULL, 0, NULL, NULL))
>> @@ -1139,7 +1144,7 @@ static int hook_file_open(struct file *const file)
>> if (is_access_to_paths_allowed(
>> dom, &file->f_path,
>> landlock_init_layer_masks(dom, full_access_request,
>> - &layer_masks),
>> + &layer_masks, LANDLOCK_KEY_INODE),
>> &layer_masks, NULL, 0, NULL, NULL)) {
>> allowed_access = full_access_request;
>> } else {
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index 22590cac3d56..9748b54b42fe 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -576,14 +576,15 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset,
>> /*
>> * @layer_masks is read and may be updated according to the access request and
>> * the matching rule.
>> + * @masks_array_size must be equal to ARRAY_SIZE(*layer_masks).
>> *
>> * Returns true if the request is allowed (i.e. relevant layer masks for the
>> * request are empty).
>> */
>> -bool landlock_unmask_layers(
>> - const struct landlock_rule *const rule,
>> - const access_mask_t access_request,
>> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
>> +bool landlock_unmask_layers(const struct landlock_rule *const rule,
>> + const access_mask_t access_request,
>> + layer_mask_t (*const layer_masks)[],
>> + const size_t masks_array_size)
>> {
>> size_t layer_level;
>>
>> @@ -615,8 +616,7 @@ bool landlock_unmask_layers(
>> * requested access.
>> */
>> is_empty = true;
>> - for_each_set_bit(access_bit, &access_req,
>> - ARRAY_SIZE(*layer_masks)) {
>> + for_each_set_bit(access_bit, &access_req, masks_array_size) {
>> if (layer->access & BIT_ULL(access_bit))
>> (*layer_masks)[access_bit] &= ~layer_bit;
>> is_empty = is_empty && !(*layer_masks)[access_bit];
>> @@ -627,6 +627,10 @@ bool landlock_unmask_layers(
>> return false;
>> }
>>
>> +typedef access_mask_t
>> +get_access_mask_t(const struct landlock_ruleset *const ruleset,
>> + const u16 layer_level);
>> +
>> /*
>> * init_layer_masks - Initialize layer masks from an access request
>> *
>> @@ -636,19 +640,34 @@ bool landlock_unmask_layers(
>> * @domain: The domain that defines the current restrictions.
>> * @access_request: The requested access rights to check.
>> * @layer_masks: The layer masks to populate.
>> + * @key_type: The key type to switch between access masks of different types.
>> *
>> * Returns: An access mask where each access right bit is set which is handled
>> * in any of the active layers in @domain.
>> */
>> -access_mask_t landlock_init_layer_masks(
>> - const struct landlock_ruleset *const domain,
>> - const access_mask_t access_request,
>> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
>> +access_mask_t
>> +landlock_init_layer_masks(const struct landlock_ruleset *const domain,
>> + const access_mask_t access_request,
>> + layer_mask_t (*const layer_masks)[],
>> + const enum landlock_key_type key_type)
>> {
>> access_mask_t handled_accesses = 0;
>> - size_t layer_level;
>> + size_t layer_level, num_access;
>> + get_access_mask_t *get_access_mask;
>> +
>> + switch (key_type) {
>> + case LANDLOCK_KEY_INODE:
>> + get_access_mask = landlock_get_fs_access_mask;
>> + num_access = LANDLOCK_NUM_ACCESS_FS;
>> + break;
>> + default:
>> + WARN_ON_ONCE(1);
>> + return 0;
>> + }
>> +
>> + memset(layer_masks, 0,
>> + array_size(sizeof((*layer_masks)[0]), num_access));
>>
>> - memset(layer_masks, 0, sizeof(*layer_masks));
>> /* An empty access request can happen because of O_WRONLY | O_RDWR. */
>> if (!access_request)
>> return 0;
>> @@ -658,10 +677,13 @@ access_mask_t landlock_init_layer_masks(
>> const unsigned long access_req = access_request;
>> unsigned long access_bit;
>>
>> - for_each_set_bit(access_bit, &access_req,
>> - ARRAY_SIZE(*layer_masks)) {
>> + for_each_set_bit(access_bit, &access_req, num_access) {
>> + /*
>> + * Artificially handles all initially denied by default
>> + * access rights.
>> + */
>> if (BIT_ULL(access_bit) &
>> - landlock_get_fs_access_mask(domain, layer_level)) {
>> + get_access_mask(domain, layer_level)) {
>> (*layer_masks)[access_bit] |=
>> BIT_ULL(layer_level);
>> handled_accesses |= BIT_ULL(access_bit);
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index 60a3c4d4d961..77349764e111 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -266,14 +266,15 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
>> return landlock_get_raw_fs_access_mask(ruleset, layer_level) |
>> ACCESS_FS_INITIALLY_DENIED;
>> }
>> -bool landlock_unmask_layers(
>> - const struct landlock_rule *const rule,
>> - const access_mask_t access_request,
>> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);
>> +bool landlock_unmask_layers(const struct landlock_rule *const rule,
>> + const access_mask_t access_request,
>> + layer_mask_t (*const layer_masks)[],
>> + const size_t masks_array_size);
>>
>> -access_mask_t landlock_init_layer_masks(
>> - const struct landlock_ruleset *const domain,
>> - const access_mask_t access_request,
>> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);
>> +access_mask_t
>> +landlock_init_layer_masks(const struct landlock_ruleset *const domain,
>> + const access_mask_t access_request,
>> + layer_mask_t (*const layer_masks)[],
>> + const enum landlock_key_type key_type);
>>
>> #endif /* _SECURITY_LANDLOCK_RULESET_H */
> .
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