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landlock: Make ruleset's access masks more generic

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Rename ruleset's access masks and modify it's type to access_masks_t
to support network type rules in following commits. Add filesystem
helper functions to add and get filesystem mask.

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20231026014751.414649-2-konstantin.meskhidze@huawei.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>
This commit is contained in:
Konstantin Meskhidze
2023-10-26 09:47:40 +08:00
committed by Mickaël Salaün
parent 05d3ef8bba
commit 13fc6455fa
5 changed files with 50 additions and 20 deletions
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10
security/landlock/fs.c
View File

@@ -178,9 +178,9 @@ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
return -EINVAL;
/* Transforms relative access rights to absolute ones. */
access_rights |=
LANDLOCK_MASK_ACCESS_FS &
~(ruleset->fs_access_masks[0] | ACCESS_INITIALLY_DENIED);
access_rights |= LANDLOCK_MASK_ACCESS_FS &
~(landlock_get_fs_access_mask(ruleset, 0) |
ACCESS_INITIALLY_DENIED);
object = get_inode_object(d_backing_inode(path->dentry));
if (IS_ERR(object))
return PTR_ERR(object);
@@ -294,7 +294,7 @@ get_handled_accesses(const struct landlock_ruleset *const domain)
size_t layer_level;
for (layer_level = 0; layer_level < domain->num_layers; layer_level++)
access_dom |= domain->fs_access_masks[layer_level];
access_dom |= landlock_get_fs_access_mask(domain, layer_level);
return access_dom & LANDLOCK_MASK_ACCESS_FS;
}
@@ -336,7 +336,7 @@ init_layer_masks(const struct landlock_ruleset *const domain,
* access rights.
*/
if (BIT_ULL(access_bit) &
(domain->fs_access_masks[layer_level] |
(landlock_get_fs_access_mask(domain, layer_level) |
ACCESS_INITIALLY_DENIED)) {
(*layer_masks)[access_bit] |=
BIT_ULL(layer_level);

1
security/landlock/limits.h
View File

@@ -21,6 +21,7 @@
#define LANDLOCK_LAST_ACCESS_FS LANDLOCK_ACCESS_FS_TRUNCATE
#define LANDLOCK_MASK_ACCESS_FS ((LANDLOCK_LAST_ACCESS_FS << 1) - 1)
#define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS)
#define LANDLOCK_SHIFT_ACCESS_FS 0
/* clang-format on */

17
security/landlock/ruleset.c
View File

@@ -29,7 +29,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
struct landlock_ruleset *new_ruleset;
new_ruleset =
kzalloc(struct_size(new_ruleset, fs_access_masks, num_layers),
kzalloc(struct_size(new_ruleset, access_masks, num_layers),
GFP_KERNEL_ACCOUNT);
if (!new_ruleset)
return ERR_PTR(-ENOMEM);
@@ -40,7 +40,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
/*
* hierarchy = NULL
* num_rules = 0
* fs_access_masks[] = 0
* access_masks[] = 0
*/
return new_ruleset;
}
@@ -55,7 +55,7 @@ landlock_create_ruleset(const access_mask_t fs_access_mask)
return ERR_PTR(-ENOMSG);
new_ruleset = create_ruleset(1);
if (!IS_ERR(new_ruleset))
new_ruleset->fs_access_masks[0] = fs_access_mask;
landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0);
return new_ruleset;
}
@@ -117,11 +117,12 @@ static void build_check_ruleset(void)
.num_rules = ~0,
.num_layers = ~0,
};
typeof(ruleset.fs_access_masks[0]) fs_access_mask = ~0;
typeof(ruleset.access_masks[0]) access_masks = ~0;
BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
BUILD_BUG_ON(fs_access_mask < LANDLOCK_MASK_ACCESS_FS);
BUILD_BUG_ON(access_masks <
(LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS));
}
/**
@@ -281,7 +282,7 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
err = -EINVAL;
goto out_unlock;
}
dst->fs_access_masks[dst->num_layers - 1] = src->fs_access_masks[0];
dst->access_masks[dst->num_layers - 1] = src->access_masks[0];
/* Merges the @src tree. */
rbtree_postorder_for_each_entry_safe(walker_rule, next_rule, &src->root,
@@ -340,8 +341,8 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
goto out_unlock;
}
/* Copies the parent layer stack and leaves a space for the new layer. */
memcpy(child->fs_access_masks, parent->fs_access_masks,
flex_array_size(parent, fs_access_masks, parent->num_layers));
memcpy(child->access_masks, parent->access_masks,
flex_array_size(parent, access_masks, parent->num_layers));
if (WARN_ON_ONCE(!parent->hierarchy)) {
err = -EINVAL;

35
security/landlock/ruleset.h
View File

@@ -25,6 +25,11 @@ static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
/* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
/* Ruleset access masks. */
typedef u16 access_masks_t;
/* Makes sure all ruleset access rights can be stored. */
static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
typedef u16 layer_mask_t;
/* Makes sure all layers can be checked. */
static_assert(BITS_PER_TYPE(layer_mask_t) >= LANDLOCK_MAX_NUM_LAYERS);
@@ -110,7 +115,7 @@ struct landlock_ruleset {
* section. This is only used by
* landlock_put_ruleset_deferred() when @usage reaches zero.
* The fields @lock, @usage, @num_rules, @num_layers and
* @fs_access_masks are then unused.
* @access_masks are then unused.
*/
struct work_struct work_free;
struct {
@@ -137,7 +142,7 @@ struct landlock_ruleset {
*/
u32 num_layers;
/**
* @fs_access_masks: Contains the subset of filesystem
* @access_masks: Contains the subset of filesystem
* actions that are restricted by a ruleset. A domain
* saves all layers of merged rulesets in a stack
* (FAM), starting from the first layer to the last
@@ -148,13 +153,13 @@ struct landlock_ruleset {
* layers are set once and never changed for the
* lifetime of the ruleset.
*/
access_mask_t fs_access_masks[];
access_masks_t access_masks[];
};
};
};
struct landlock_ruleset *
landlock_create_ruleset(const access_mask_t fs_access_mask);
landlock_create_ruleset(const access_mask_t access_mask);
void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
@@ -177,4 +182,26 @@ static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset)
refcount_inc(&ruleset->usage);
}
static inline void
landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset,
const access_mask_t fs_access_mask,
const u16 layer_level)
{
access_mask_t fs_mask = fs_access_mask & LANDLOCK_MASK_ACCESS_FS;
/* Should already be checked in sys_landlock_create_ruleset(). */
WARN_ON_ONCE(fs_access_mask != fs_mask);
ruleset->access_masks[layer_level] |=
(fs_mask << LANDLOCK_SHIFT_ACCESS_FS);
}
static inline access_mask_t
landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
const u16 layer_level)
{
return (ruleset->access_masks[layer_level] >>
LANDLOCK_SHIFT_ACCESS_FS) &
LANDLOCK_MASK_ACCESS_FS;
}
#endif /* _SECURITY_LANDLOCK_RULESET_H */

7
security/landlock/syscalls.c
View File

@@ -310,6 +310,7 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
struct path path;
struct landlock_ruleset *ruleset;
int res, err;
access_mask_t mask;
if (!landlock_initialized)
return -EOPNOTSUPP;
@@ -346,10 +347,10 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
}
/*
* Checks that allowed_access matches the @ruleset constraints
* (ruleset->fs_access_masks[0] is automatically upgraded to 64-bits).
* (ruleset->access_masks[0] is automatically upgraded to 64-bits).
*/
if ((path_beneath_attr.allowed_access | ruleset->fs_access_masks[0]) !=
ruleset->fs_access_masks[0]) {
mask = landlock_get_fs_access_mask(ruleset, 0);
if ((path_beneath_attr.allowed_access | mask) != mask) {
err = -EINVAL;
goto out_put_ruleset;
}