[PATCH v5 04/15] landlock: helper functions refactoring
Konstantin Meskhidze
konstantin.meskhidze at huawei.com
Mon May 16 17:43:37 UTC 2022
5/16/2022 8:14 PM, Mickaël Salaün пишет:
>
> On 16/05/2022 17:20, Konstantin Meskhidze wrote:
>> Unmask_layers(), init_layer_masks() and
>> get_handled_accesses() helper functions move to
>> ruleset.c and rule_type argument is added.
>> This modification supports implementing new rule
>> types into next landlock versions.
>>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze at huawei.com>
>> ---
>>
>> Changes since v3:
>> * Splits commit.
>> * Refactoring landlock_unmask_layers functions.
>>
>
> Please sort changes in antichronological order. It is easier to look at
> the first lines to get the last changes.
Ok. I will. Thanks
>
>> Changes since v4:
>> * Refactoring init_layer_masks(), get_handled_accesses()
>> and unmask_layers() functions to support multiple rule types.
>> * Refactoring landlock_get_fs_access_mask() function with
>> LANDLOCK_MASK_ACCESS_FS mask. >
>> ---
>> security/landlock/fs.c | 158 ++++++++----------------------------
>> security/landlock/ruleset.c | 152 +++++++++++++++++++++++++++++++---
>> security/landlock/ruleset.h | 17 +++-
>> 3 files changed, 192 insertions(+), 135 deletions(-)
>>
>> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
>> index 5de24d4dd74c..3506e182b23e 100644
>> --- a/security/landlock/fs.c
>> +++ b/security/landlock/fs.c
>> @@ -211,60 +211,6 @@ find_rule(const struct landlock_ruleset *const
>> domain,
>> return rule;
>> }
>>
>> -/*
>> - * @layer_masks is read and may be updated according to the access
>> request and
>> - * the matching rule.
>> - *
>> - * Returns true if the request is allowed (i.e. relevant layer masks
>> for the
>> - * request are empty).
>> - */
>> -static inline 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])
>
> Moving these entire blocks of code make the review/diff impossible. Why
> moving these helpers?
Cause these helpers are going to be used both for filesystem and
network. I moved them into ruleset.c/h
>
>> -{
>> - size_t layer_level;
>> -
>> - if (!access_request || !layer_masks)
>> - return true;
>> - if (!rule)
>> - return false;
>> -
>> - /*
>> - * An access is granted if, for each policy layer, at least one rule
>> - * encountered on the pathwalk grants the requested access,
>> - * regardless of its position in the layer stack. We must then
>> check
>> - * the remaining layers for each inode, from the first added
>> layer to
>> - * the last one. When there is multiple requested accesses, for
>> each
>> - * policy layer, the full set of requested accesses may not be
>> granted
>> - * by only one rule, but by the union (binary OR) of multiple rules.
>> - * E.g. /a/b <execute> + /a <read> => /a/b <execute + read>
>> - */
>> - for (layer_level = 0; layer_level < rule->num_layers;
>> layer_level++) {
>> - const struct landlock_layer *const layer =
>> - &rule->layers[layer_level];
>> - const layer_mask_t layer_bit = BIT_ULL(layer->level - 1);
>> - const unsigned long access_req = access_request;
>> - unsigned long access_bit;
>> - bool is_empty;
>> -
>> - /*
>> - * Records in @layer_masks which layer grants access to each
>> - * requested access.
>> - */
>> - is_empty = true;
>> - for_each_set_bit(access_bit, &access_req,
>> - ARRAY_SIZE(*layer_masks)) {
>> - if (layer->access & BIT_ULL(access_bit))
>> - (*layer_masks)[access_bit] &= ~layer_bit;
>> - is_empty = is_empty && !(*layer_masks)[access_bit];
>> - }
>> - if (is_empty)
>> - return true;
>> - }
>> - return false;
>> -}
>> -
>> /*
>> * Allows access to pseudo filesystems that will never be mountable
>> (e.g.
>> * sockfs, pipefs), but can still be reachable through
>> @@ -277,59 +223,6 @@ static inline bool is_nouser_or_private(const
>> struct dentry *dentry)
>> unlikely(IS_PRIVATE(d_backing_inode(dentry))));
>> }
>>
>> -static inline access_mask_t
>> -get_handled_accesses(const struct landlock_ruleset *const domain)
>> -{
>> - access_mask_t access_dom = 0;
>> - unsigned long access_bit;
>> -
>> - for (access_bit = 0; access_bit < LANDLOCK_NUM_ACCESS_FS;
>> - access_bit++) {
>> - size_t layer_level;
>> -
>> - for (layer_level = 0; layer_level < domain->num_layers;
>> - layer_level++) {
>> - if (landlock_get_fs_access_mask(domain, layer_level) &
>> - BIT_ULL(access_bit)) {
>> - access_dom |= BIT_ULL(access_bit);
>> - break;
>> - }
>> - }
>> - }
>> - return access_dom;
>> -}
>> -
>> -static inline 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 handled_accesses = 0;
>> - size_t layer_level;
>> -
>> - memset(layer_masks, 0, sizeof(*layer_masks));
>> - /* An empty access request can happen because of O_WRONLY |
>> O_RDWR. */
>> - if (!access_request)
>> - return 0;
>> -
>> - /* Saves all handled accesses per layer. */
>> - for (layer_level = 0; layer_level < domain->num_layers;
>> layer_level++) {
>> - 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) &
>> - BIT_ULL(access_bit)) {
>> - (*layer_masks)[access_bit] |=
>> - BIT_ULL(layer_level);
>> - handled_accesses |= BIT_ULL(access_bit);
>> - }
>> - }
>> - }
>> - return handled_accesses;
>> -}
>> -
>> /*
>> * Check that a destination file hierarchy has more restrictions
>> than a source
>> * file hierarchy. This is only used for link and rename actions.
>> @@ -506,7 +399,8 @@ static int check_access_path_dual(
>> * a superset of the meaningful requested accesses).
>> */
>> access_masked_parent1 = access_masked_parent2 =
>> - get_handled_accesses(domain);
>> + get_handled_accesses(domain, LANDLOCK_RULE_PATH_BENEATH,
>> + LANDLOCK_NUM_ACCESS_FS);
>> is_dom_check = true;
>> } else {
>> if (WARN_ON_ONCE(dentry_child1 || dentry_child2))
>> @@ -519,17 +413,25 @@ 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);
>> + init_layer_masks(domain,
>> + LANDLOCK_MASK_ACCESS_FS,
>> + &_layer_masks_child1,
>> + sizeof(_layer_masks_child1),
>> + LANDLOCK_RULE_PATH_BENEATH),
>> + &_layer_masks_child1,
>> + ARRAY_SIZE(_layer_masks_child1));
>
> There is a lot of formatting diff and that makes the review difficult.
> Please format everything with clang-format-14.
Ok. Do you have some tool that helps you with editing code with clang
format?
>
>> 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);
>> + init_layer_masks(domain,
>> + LANDLOCK_MASK_ACCESS_FS,
>> + &_layer_masks_child2,
>> + sizeof(_layer_masks_child2),
>> + LANDLOCK_RULE_PATH_BENEATH),
>> + &_layer_masks_child2,
>> + ARRAY_SIZE(_layer_masks_child2));
>> layer_masks_child2 = &_layer_masks_child2;
>> child2_is_directory = d_is_dir(dentry_child2);
>> }
>> @@ -582,14 +484,15 @@ static int check_access_path_dual(
>>
>> rule = find_rule(domain, walker_path.dentry);
>> allowed_parent1 = unmask_layers(rule, access_masked_parent1,
>> - layer_masks_parent1);
>> + layer_masks_parent1,
>> + ARRAY_SIZE(*layer_masks_parent1));
>> allowed_parent2 = unmask_layers(rule, access_masked_parent2,
>> - layer_masks_parent2);
>> + layer_masks_parent2,
>> + ARRAY_SIZE(*layer_masks_parent2));
>>
>> /* Stops when a rule from each layer grants access. */
>> if (allowed_parent1 && allowed_parent2)
>> break;
>> -
>
> There is no place for such formatting/whitespace patches.
>
I missed that. scripts/checkpatch.pl did not show any problem here.
I will fix it. Thanks.
>
>> jump_up:
>> if (walker_path.dentry == walker_path.mnt->mnt_root) {
>> if (follow_up(&walker_path)) {
>> @@ -645,7 +548,9 @@ 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, sizeof(layer_masks),
>> + LANDLOCK_RULE_PATH_BENEATH);
>> return check_access_path_dual(domain, path, access_request,
>> &layer_masks, NULL, 0, NULL, NULL);
>> }
>> @@ -729,7 +634,8 @@ static bool collect_domain_accesses(
>> return true;
>>
>> access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> - layer_masks_dom);
>> + layer_masks_dom, sizeof(*layer_masks_dom),
>> + LANDLOCK_RULE_PATH_BENEATH);
>>
>> dget(dir);
>> while (true) {
>> @@ -737,7 +643,8 @@ 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.
>> @@ -851,9 +758,10 @@ static int current_check_refer_path(struct dentry
>> *const old_dentry,
>> * The LANDLOCK_ACCESS_FS_REFER access right is not required
>> * for same-directory referer (i.e. no reparenting).
>> */
>> - access_request_parent1 = init_layer_masks(
>> - dom, access_request_parent1 | access_request_parent2,
>> - &layer_masks_parent1);
>> + access_request_parent1 = init_layer_masks(dom,
>> + access_request_parent1 | access_request_parent2,
>> + &layer_masks_parent1, sizeof(layer_masks_parent1),
>> + LANDLOCK_RULE_PATH_BENEATH);
>> return check_access_path_dual(dom, new_dir,
>> access_request_parent1,
>> &layer_masks_parent1, NULL, 0,
>> @@ -861,7 +769,9 @@ static int current_check_refer_path(struct dentry
>> *const old_dentry,
>> }
>>
>> /* Backward compatibility: no reparenting support. */
>> - if (!(get_handled_accesses(dom) & LANDLOCK_ACCESS_FS_REFER))
>> + if (!(get_handled_accesses(dom, LANDLOCK_RULE_PATH_BENEATH,
>> + LANDLOCK_NUM_ACCESS_FS) &
>> + LANDLOCK_ACCESS_FS_REFER))
>> return -EXDEV;
>>
>> access_request_parent1 |= LANDLOCK_ACCESS_FS_REFER;
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index 4b4c9953bb32..c4ed783d655b 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -233,7 +233,8 @@ static int insert_rule(struct landlock_ruleset
>> *const ruleset,
>> &(*layers)[0]);
>> if (IS_ERR(new_rule))
>> return PTR_ERR(new_rule);
>> - rb_replace_node(&this->node, &new_rule->node,
>> &ruleset->root_inode);
>> + rb_replace_node(&this->node, &new_rule->node,
>> + &ruleset->root_inode);
>
> This is a pure formatting hunk. :/
>
Thats strange, cause in my editor I have normal aligment of arguments.
Could please share clang-format-14 tab size and other format parameters?
>
>> free_rule(this, rule_type);
>> break;
>> }
>> @@ -246,7 +247,8 @@ static int insert_rule(struct landlock_ruleset
>> *const ruleset,
>> return -E2BIG;
>> switch (rule_type) {
>> case LANDLOCK_RULE_PATH_BENEATH:
>> - new_rule = create_rule(object_ptr, 0, layers, num_layers, NULL);
>> + new_rule = create_rule(object_ptr, 0, layers,
>> + num_layers, NULL);
>> if (IS_ERR(new_rule))
>> return PTR_ERR(new_rule);
>> rb_link_node(&new_rule->node, parent_node, walker_node);
>> @@ -281,8 +283,8 @@ int landlock_insert_rule(struct landlock_ruleset
>> *const ruleset,
>> } };
>>
>> build_check_layer();
>> - return insert_rule(ruleset, object_ptr, object_data, rule_type,
>> &layers,
>> - ARRAY_SIZE(layers));
>> + return insert_rule(ruleset, object_ptr, object_data, rule_type,
>> + &layers, ARRAY_SIZE(layers));
>> }
>>
>> static inline void get_hierarchy(struct landlock_hierarchy *const
>> hierarchy)
>> @@ -335,8 +337,9 @@ static int tree_merge(struct landlock_ruleset
>> *const src,
>>
>> switch (rule_type) {
>> case LANDLOCK_RULE_PATH_BENEATH:
>> - err = insert_rule(dst, walker_rule->object.ptr, 0,
>> rule_type,
>> - &layers, ARRAY_SIZE(layers));
>> + err = insert_rule(dst, walker_rule->object.ptr, 0,
>> + rule_type, &layers,
>> + ARRAY_SIZE(layers));
>> break;
>> }
>> if (err)
>> @@ -433,9 +436,13 @@ static int inherit_ruleset(struct
>> landlock_ruleset *const parent,
>> err = -EINVAL;
>> goto out_unlock;
>> }
>> - /* Copies the parent layer stack and leaves a space for the new
>> layer. */
>> + /*
>> + * Copies the parent layer stack and leaves a space
>> + * for the new layer.
>> + */
>> memcpy(child->access_masks, parent->access_masks,
>> - flex_array_size(parent, access_masks, parent->num_layers));
>> + flex_array_size(parent, access_masks,
>> + parent->num_layers));
>>
>> if (WARN_ON_ONCE(!parent->hierarchy)) {
>> err = -EINVAL;
>> @@ -455,8 +462,9 @@ static void free_ruleset(struct landlock_ruleset
>> *const ruleset)
>> struct landlock_rule *freeme, *next;
>>
>> might_sleep();
>> - rbtree_postorder_for_each_entry_safe(freeme, next,
>> &ruleset->root_inode,
>> - node)
>> + rbtree_postorder_for_each_entry_safe(freeme, next,
>> + &ruleset->root_inode,
>> + node)
>> free_rule(freeme, LANDLOCK_RULE_PATH_BENEATH);
>> put_hierarchy(ruleset->hierarchy);
>> kfree(ruleset);
>> @@ -577,3 +585,127 @@ const struct landlock_rule *landlock_find_rule(
>> }
>> return NULL;
>> }
>> +
>> +access_mask_t get_handled_accesses(
>> + const struct landlock_ruleset *const domain,
>> + u16 rule_type, u16 num_access)
>> +{
>> + access_mask_t access_dom = 0;
>> + unsigned long access_bit;
>> +
>> + switch (rule_type) {
>> + case LANDLOCK_RULE_PATH_BENEATH:
>> + for (access_bit = 0; access_bit < LANDLOCK_NUM_ACCESS_FS;
>> + access_bit++) {
>> + size_t layer_level;
>> +
>> + for (layer_level = 0; layer_level < domain->num_layers;
>> + layer_level++) {
>> + if (landlock_get_fs_access_mask(domain,
>> + layer_level) &
>> + BIT_ULL(access_bit)) {
>> + access_dom |= BIT_ULL(access_bit);
>> + break;
>> + }
>> + }
>> + }
>> + break;
>> + default:
>> + break;
>> + }
>> + return access_dom;
>> +}
>> +
>> +/*
>> + * @layer_masks is read and may be updated according to the access
>> request and
>> + * the matching rule.
>> + *
>> + * Returns true if the request is allowed (i.e. relevant layer masks
>> for the
>> + * request are empty).
>> + */
>> +bool unmask_layers(const struct landlock_rule *const rule,
>> + const access_mask_t access_request,
>> + layer_mask_t (*const layer_masks)[], size_t masks_array_size)
>> +{
>> + size_t layer_level;
>> +
>> + if (!access_request || !layer_masks)
>> + return true;
>> + if (!rule)
>> + return false;
>> +
>> + /*
>> + * An access is granted if, for each policy layer, at least one rule
>> + * encountered on the pathwalk grants the requested access,
>> + * regardless of its position in the layer stack. We must then
>> check
>> + * the remaining layers for each inode, from the first added
>> layer to
>> + * the last one. When there is multiple requested accesses, for
>> each
>> + * policy layer, the full set of requested accesses may not be
>> granted
>> + * by only one rule, but by the union (binary OR) of multiple rules.
>> + * E.g. /a/b <execute> + /a <read> => /a/b <execute + read>
>> + */
>> + for (layer_level = 0; layer_level < rule->num_layers;
>> layer_level++) {
>> + const struct landlock_layer *const layer =
>> + &rule->layers[layer_level];
>> + const layer_mask_t layer_bit = BIT_ULL(layer->level - 1);
>> + const unsigned long access_req = access_request;
>> + unsigned long access_bit;
>> + bool is_empty;
>> +
>> + /*
>> + * Records in @layer_masks which layer grants access to each
>> + * requested access.
>> + */
>> + is_empty = true;
>> + 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];
>> + }
>> + if (is_empty)
>> + return true;
>> + }
>> + 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)[],
>> + size_t masks_size,
>> + u16 rule_type)
>> +{
>> + access_mask_t handled_accesses = 0;
>> + size_t layer_level;
>> +
>> + memset(layer_masks, 0, masks_size);
>> +
>> + /* An empty access request can happen because of O_WRONLY |
>> O_RDWR. */
>> + if (!access_request)
>> + return 0;
>> +
>> + /* Saves all handled accesses per layer. */
>> + for (layer_level = 0; layer_level < domain->num_layers;
>> + layer_level++) {
>> + const unsigned long access_req = access_request;
>> + unsigned long access_bit;
>> +
>> + switch (rule_type) {
>> + case LANDLOCK_RULE_PATH_BENEATH:
>> + for_each_set_bit(access_bit, &access_req,
>> + LANDLOCK_NUM_ACCESS_FS) {
>> + if (landlock_get_fs_access_mask(domain,
>> + layer_level) &
>> + BIT_ULL(access_bit)) {
>> + (*layer_masks)[access_bit] |=
>> + BIT_ULL(layer_level);
>> + handled_accesses |=
>> + BIT_ULL(access_bit);
>> + }
>> + }
>> + break;
>> + default:
>> + return 0;
>> + }
>> + }
>> + return handled_accesses;
>> +}
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index 3066e5d7180c..f3cd890d0348 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -195,7 +195,22 @@ static inline u32 landlock_get_fs_access_mask(
>> const struct landlock_ruleset *ruleset,
>> u16 mask_level)
>> {
>> - return ruleset->access_masks[mask_level];
>> + return (ruleset->access_masks[mask_level] &
>> LANDLOCK_MASK_ACCESS_FS);
>> }
>>
>> +access_mask_t get_handled_accesses(
>> + const struct landlock_ruleset *const domain,
>> + u16 rule_type, u16 num_access);
>> +
>> +bool unmask_layers(const struct landlock_rule *const rule,
>> + const access_mask_t access_request,
>> + layer_mask_t (*const layer_masks)[],
>> + 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)[],
>> + size_t masks_size,
>> + u16 rule_type);
>
> These declarations are useless.
I moved helpers in rulset.c/h to use them both for filesystem
and network.
>
>> +
>> #endif /* _SECURITY_LANDLOCK_RULESET_H */
>> --
>> 2.25.1
>>
> .
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