The per-layer FAM in struct landlock_ruleset currently stores struct access_masks directly, but upcoming permission features (capability and namespace restrictions) need additional per-layer data beyond the handled-access bitfields. Introduce struct layer_rights as a wrapper around struct access_masks and rename the FAM from access_masks[] to layers[]. This makes room for future per-layer fields (e.g. allowed bitmasks) without modifying struct access_masks itself, which is also used as a lightweight parameter type for functions that only need the handled-access bitfields. No functional change. Cc: Günther Noack Signed-off-by: Mickaël Salaün --- security/landlock/access.h | 29 ++++++++++++++++++++++------- security/landlock/cred.h | 2 +- security/landlock/ruleset.c | 12 ++++++------ security/landlock/ruleset.h | 28 +++++++++++++++------------- security/landlock/syscalls.c | 2 +- 5 files changed, 45 insertions(+), 28 deletions(-) diff --git a/security/landlock/access.h b/security/landlock/access.h index 42c95747d7bd..b3e147771a0e 100644 --- a/security/landlock/access.h +++ b/security/landlock/access.h @@ -19,7 +19,7 @@ /* * All access rights that are denied by default whether they are handled or not - * by a ruleset/layer. This must be ORed with all ruleset->access_masks[] + * by a ruleset/layer. This must be ORed with all ruleset->layers[] * entries when we need to get the absolute handled access masks, see * landlock_upgrade_handled_access_masks(). */ @@ -45,7 +45,7 @@ static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_SCOPE); /* 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. */ +/* Handled access masks (bitfields only). */ struct access_masks { access_mask_t fs : LANDLOCK_NUM_ACCESS_FS; access_mask_t net : LANDLOCK_NUM_ACCESS_NET; @@ -61,6 +61,21 @@ union access_masks_all { static_assert(sizeof(typeof_member(union access_masks_all, masks)) == sizeof(typeof_member(union access_masks_all, all))); +/** + * struct layer_rights - Per-layer access configuration + * + * Wraps the handled-access bitfields together with any additional per-layer + * data (e.g. allowed bitmasks added by future patches). This is the element + * type of the &struct landlock_ruleset.layers FAM. + */ +struct layer_rights { + /** + * @handled: Bitmask of access rights handled (i.e. restricted) by + * this layer. + */ + struct access_masks handled; +}; + /** * struct layer_access_masks - A boolean matrix of layers and access rights * @@ -100,17 +115,17 @@ static_assert(BITS_PER_TYPE(deny_masks_t) >= static_assert(HWEIGHT(LANDLOCK_MAX_NUM_LAYERS) == 1); /* Upgrades with all initially denied by default access rights. */ -static inline struct access_masks -landlock_upgrade_handled_access_masks(struct access_masks access_masks) +static inline struct layer_rights +landlock_upgrade_handled_access_masks(struct layer_rights layer_rights) { /* * All access rights that are denied by default whether they are * explicitly handled or not. */ - if (access_masks.fs) - access_masks.fs |= _LANDLOCK_ACCESS_FS_INITIALLY_DENIED; + if (layer_rights.handled.fs) + layer_rights.handled.fs |= _LANDLOCK_ACCESS_FS_INITIALLY_DENIED; - return access_masks; + return layer_rights; } /* Checks the subset relation between access masks. */ diff --git a/security/landlock/cred.h b/security/landlock/cred.h index f287c56b5fd4..3e2a7e88710e 100644 --- a/security/landlock/cred.h +++ b/security/landlock/cred.h @@ -139,7 +139,7 @@ landlock_get_applicable_subject(const struct cred *const cred, for (layer_level = domain->num_layers - 1; layer_level >= 0; layer_level--) { union access_masks_all layer = { - .masks = domain->access_masks[layer_level], + .masks = domain->layers[layer_level].handled, }; if (layer.all & masks_all.all) { diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index 181df7736bb9..a7f8be37ec31 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -32,7 +32,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) { struct landlock_ruleset *new_ruleset; - new_ruleset = kzalloc_flex(*new_ruleset, access_masks, num_layers, + new_ruleset = kzalloc_flex(*new_ruleset, layers, num_layers, GFP_KERNEL_ACCOUNT); if (!new_ruleset) return ERR_PTR(-ENOMEM); @@ -48,7 +48,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) /* * hierarchy = NULL * num_rules = 0 - * access_masks[] = 0 + * layers[] = 0 */ return new_ruleset; } @@ -381,8 +381,8 @@ static int merge_ruleset(struct landlock_ruleset *const dst, err = -EINVAL; goto out_unlock; } - dst->access_masks[dst->num_layers - 1] = - landlock_upgrade_handled_access_masks(src->access_masks[0]); + dst->layers[dst->num_layers - 1] = + landlock_upgrade_handled_access_masks(src->layers[0]); /* Merges the @src inode tree. */ err = merge_tree(dst, src, LANDLOCK_KEY_INODE); @@ -464,8 +464,8 @@ 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->access_masks, parent->access_masks, - flex_array_size(parent, access_masks, parent->num_layers)); + memcpy(child->layers, parent->layers, + flex_array_size(parent, layers, parent->num_layers)); if (WARN_ON_ONCE(!parent->hierarchy)) { err = -EINVAL; diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 889f4b30301a..900c47eb0216 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -146,7 +146,7 @@ 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 - * @access_masks are then unused. + * @layers are then unused. */ struct work_struct work_free; struct { @@ -173,9 +173,10 @@ struct landlock_ruleset { */ u32 num_layers; /** - * @access_masks: Contains the subset of filesystem and - * network actions that are restricted by a ruleset. - * A domain saves all layers of merged rulesets in a + * @layers: Per-layer access configuration, including + * handled access masks and allowed permission + * bitmasks. A domain saves all layers of merged + * rulesets in a * stack (FAM), starting from the first layer to the * last one. These layers are used when merging * rulesets, for user space backward compatibility @@ -184,7 +185,7 @@ struct landlock_ruleset { * layers are set once and never changed for the * lifetime of the ruleset. */ - struct access_masks access_masks[]; + struct layer_rights layers[] __counted_by(num_layers); }; }; }; @@ -224,7 +225,8 @@ static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset) * * @domain: Landlock ruleset (used as a domain) * - * Return: An access_masks result of the OR of all the domain's access masks. + * Return: An access_masks result of the OR of all the domain's handled access + * masks. */ static inline struct access_masks landlock_union_access_masks(const struct landlock_ruleset *const domain) @@ -234,7 +236,7 @@ landlock_union_access_masks(const struct landlock_ruleset *const domain) for (layer_level = 0; layer_level < domain->num_layers; layer_level++) { union access_masks_all layer = { - .masks = domain->access_masks[layer_level], + .masks = domain->layers[layer_level].handled, }; matches.all |= layer.all; @@ -252,7 +254,7 @@ landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset, /* Should already be checked in sys_landlock_create_ruleset(). */ WARN_ON_ONCE(fs_access_mask != fs_mask); - ruleset->access_masks[layer_level].fs |= fs_mask; + ruleset->layers[layer_level].handled.fs |= fs_mask; } static inline void @@ -264,7 +266,7 @@ landlock_add_net_access_mask(struct landlock_ruleset *const ruleset, /* Should already be checked in sys_landlock_create_ruleset(). */ WARN_ON_ONCE(net_access_mask != net_mask); - ruleset->access_masks[layer_level].net |= net_mask; + ruleset->layers[layer_level].handled.net |= net_mask; } static inline void @@ -275,7 +277,7 @@ landlock_add_scope_mask(struct landlock_ruleset *const ruleset, /* Should already be checked in sys_landlock_create_ruleset(). */ WARN_ON_ONCE(scope_mask != mask); - ruleset->access_masks[layer_level].scope |= mask; + ruleset->layers[layer_level].handled.scope |= mask; } static inline access_mask_t @@ -283,7 +285,7 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, const u16 layer_level) { /* Handles all initially denied by default access rights. */ - return ruleset->access_masks[layer_level].fs | + return ruleset->layers[layer_level].handled.fs | _LANDLOCK_ACCESS_FS_INITIALLY_DENIED; } @@ -291,14 +293,14 @@ static inline access_mask_t landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset, const u16 layer_level) { - return ruleset->access_masks[layer_level].net; + return ruleset->layers[layer_level].handled.net; } static inline access_mask_t landlock_get_scope_mask(const struct landlock_ruleset *const ruleset, const u16 layer_level) { - return ruleset->access_masks[layer_level].scope; + return ruleset->layers[layer_level].handled.scope; } bool landlock_unmask_layers(const struct landlock_rule *const rule, diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index 3b33839b80c7..2aa7b50d875f 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -341,7 +341,7 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, return -ENOMSG; /* Checks that allowed_access matches the @ruleset constraints. */ - mask = ruleset->access_masks[0].fs; + mask = ruleset->layers[0].handled.fs; if ((path_beneath_attr.allowed_access | mask) != mask) return -EINVAL; -- 2.53.0