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Date: Tue, 6 Sep 2022 10:07:41 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
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,
hukeping@...wei.com, anton.sirazetdinov@...wei.com
Subject: Re: [PATCH v7 05/18] landlock: refactor helper functions
You can improve the subject with: "landlock: Refactor unmask_layers()
and init_layer_masks()"
On 29/08/2022 19:03, Konstantin Meskhidze wrote:
> Adds new key_type argument to init_layer_masks() helper functions.
> This modification supports implementing new rule types in the next
> Landlock versions.
>
> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
As for patch 2/18, you can append:
Co-developed-by: Mickaël Salaün <mic@...ikod.net>
> ---
>
> 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 | 33 +++++++++++++++++-----------
> security/landlock/ruleset.c | 44 +++++++++++++++++++++++++++----------
> security/landlock/ruleset.h | 11 +++++-----
> 3 files changed, 58 insertions(+), 30 deletions(-)
>
> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
> index b03d6153f628..a4d9aea539cd 100644
> --- a/security/landlock/fs.c
> +++ b/security/landlock/fs.c
> @@ -439,16 +439,20 @@ static int check_access_path_dual(
> if (unlikely(dentry_child1)) {
> unmask_layers(find_rule(domain, dentry_child1),
> init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
> - &_layer_masks_child1),
> - &_layer_masks_child1);
> + &_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)) {
> unmask_layers(find_rule(domain, dentry_child2),
> init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
> - &_layer_masks_child2),
> - &_layer_masks_child2);
> + &_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);
> }
> @@ -500,15 +504,16 @@ static int check_access_path_dual(
> }
>
> rule = find_rule(domain, walker_path.dentry);
> - allowed_parent1 = unmask_layers(rule, access_masked_parent1,
> - layer_masks_parent1);
> - allowed_parent2 = unmask_layers(rule, access_masked_parent2,
> - layer_masks_parent2);
> + allowed_parent1 = unmask_layers(
> + rule, access_masked_parent1, layer_masks_parent1,
> + ARRAY_SIZE(*layer_masks_parent1));
> + allowed_parent2 = unmask_layers(
> + 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)) {
> @@ -564,7 +569,8 @@ static inline int check_access_path(const struct landlock_ruleset *const domain,
> {
> layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
>
> - access_request = init_layer_masks(domain, access_request, &layer_masks);
> + access_request = init_layer_masks(domain, access_request, &layer_masks,
> + LANDLOCK_KEY_INODE);
> return check_access_path_dual(domain, path, access_request,
> &layer_masks, NULL, 0, NULL, NULL);
> }
> @@ -648,7 +654,7 @@ static bool collect_domain_accesses(
> return true;
>
> access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
> - layer_masks_dom);
> + layer_masks_dom, LANDLOCK_KEY_INODE);
>
> dget(dir);
> while (true) {
> @@ -656,7 +662,8 @@ static bool collect_domain_accesses(
>
> /* Gets all layers allowing all domain accesses. */
> if (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.
> @@ -772,7 +779,7 @@ static int current_check_refer_path(struct dentry *const old_dentry,
> */
> access_request_parent1 = init_layer_masks(
> dom, access_request_parent1 | access_request_parent2,
> - &layer_masks_parent1);
> + &layer_masks_parent1, LANDLOCK_KEY_INODE);
> return check_access_path_dual(dom, new_dir,
> access_request_parent1,
> &layer_masks_parent1, NULL, 0,
> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
> index 671a95e2a345..84fcd8eb30d4 100644
> --- a/security/landlock/ruleset.c
> +++ b/security/landlock/ruleset.c
> @@ -574,7 +574,8 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset,
> */
You missed another hunk from my patch… Please do a diff with it.
> bool unmask_layers(const struct landlock_rule *const rule,
> const access_mask_t access_request,
> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
> + layer_mask_t (*const layer_masks)[],
> + const size_t masks_array_size)
> {
> size_t layer_level;
>
> @@ -606,8 +607,7 @@ bool unmask_layers(const struct landlock_rule *const rule,
> * 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];
> @@ -618,15 +618,36 @@ bool unmask_layers(const struct landlock_rule *const rule,
> return false;
> }
>
> -access_mask_t
> -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])
> +typedef access_mask_t
> +get_access_mask_t(const struct landlock_ruleset *const ruleset,
> + const u16 layer_level);
> +
> +/*
> + * @layer_masks must contain LANDLOCK_NUM_ACCESS_FS or LANDLOCK_NUM_ACCESS_NET
> + * elements according to @key_type.
> + */
> +access_mask_t 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;
> @@ -636,9 +657,8 @@ init_layer_masks(const struct landlock_ruleset *const domain,
> const unsigned long access_req = access_request;
> unsigned long access_bit;
>
> - for_each_set_bit(access_bit, &access_req,
> - ARRAY_SIZE(*layer_masks)) {
> - if (landlock_get_fs_access_mask(domain, layer_level) &
> + for_each_set_bit(access_bit, &access_req, num_access) {
> + if (get_access_mask(domain, layer_level) &
> BIT_ULL(access_bit)) {
> (*layer_masks)[access_bit] |=
> BIT_ULL(layer_level);
> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
> index d7d9b987829c..2083855bf42d 100644
> --- a/security/landlock/ruleset.h
> +++ b/security/landlock/ruleset.h
> @@ -238,11 +238,12 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
>
> bool unmask_layers(const struct landlock_rule *const rule,
> const access_mask_t access_request,
> - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);
> + layer_mask_t (*const layer_masks)[],
> + const size_t masks_array_size);
>
> -access_mask_t
> -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 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 */
> --
> 2.25.1
>
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