Re: [PATCH v6 01/17] landlock: renames access mask

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7/1/2022 8:08 PM, Mickaël Salaün пишет:

On 21/06/2022 10:22, Konstantin Meskhidze wrote:
To support network type rules,
this modification extends and renames
ruleset's access masks.
This patch adds filesystem helper functions
to set and get filesystem mask. Also the
modification adds a helper structure
landlock_access_mask to support managing
multiple access mask.

Please use a text-width of 72 columns for all commit messages. You can
also split them into paragraphs.

  By the way, are you going to review the rest patches?

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@xxxxxxxxxx>
---

Changes since v5:
* Changes access_mask_t to u32.
* Formats code with clang-format-14.

Changes since v4:
* Deletes struct landlock_access_mask.

Changes since v3:
* Splits commit.
* Adds get_mask, set_mask helpers for filesystem.
* Adds new struct landlock_access_mask.

---
  security/landlock/fs.c       |  7 ++++---
  security/landlock/ruleset.c  | 18 +++++++++---------
  security/landlock/ruleset.h  | 25 ++++++++++++++++++++-----
  security/landlock/syscalls.c |  7 ++++---
  4 files changed, 37 insertions(+), 20 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index ec5a6247cd3e..e6da08ed99d1 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -167,7 +167,8 @@ 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_rights |= LANDLOCK_MASK_ACCESS_FS &
+			 ~landlock_get_fs_access_mask(ruleset, 0);
  	object = get_inode_object(d_backing_inode(path->dentry));
  	if (IS_ERR(object))
  		return PTR_ERR(object);
@@ -286,7 +287,7 @@ get_handled_accesses(const struct landlock_ruleset *const domain)

  		for (layer_level = 0; layer_level < domain->num_layers;
  		     layer_level++) {
-			if (domain->fs_access_masks[layer_level] &
+			if (landlock_get_fs_access_mask(domain, layer_level) &
  			    BIT_ULL(access_bit)) {
  				access_dom |= BIT_ULL(access_bit);
  				break;
@@ -316,7 +317,7 @@ init_layer_masks(const struct landlock_ruleset *const domain,

  		for_each_set_bit(access_bit, &access_req,
  				 ARRAY_SIZE(*layer_masks)) {
-			if (domain->fs_access_masks[layer_level] &
+			if (landlock_get_fs_access_mask(domain, layer_level) &
  			    BIT_ULL(access_bit)) {
  				(*layer_masks)[access_bit] |=
  					BIT_ULL(layer_level);
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index 996484f98bfd..a3fd58d01f09 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -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);
@@ -40,22 +40,22 @@ 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;
  }

  struct landlock_ruleset *
-landlock_create_ruleset(const access_mask_t fs_access_mask)
+landlock_create_ruleset(const access_mask_t access_mask)
  {
  	struct landlock_ruleset *new_ruleset;

  	/* Informs about useless ruleset. */
-	if (!fs_access_mask)
+	if (!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_set_fs_access_mask(new_ruleset, access_mask, 0);
  	return new_ruleset;
  }

@@ -117,7 +117,7 @@ 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]) fs_access_mask = ~0;

  	BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
  	BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
@@ -281,7 +281,7 @@ 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 +340,8 @@ 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;
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index d43231b783e4..bd7ab39859bf 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -19,7 +19,7 @@
  #include "limits.h"
  #include "object.h"

-typedef u16 access_mask_t;
+typedef u32 access_mask_t;
  /* Makes sure all filesystem access rights can be stored. */
  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. */
@@ -110,7 +110,7 @@ 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 +137,7 @@ 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 +148,13 @@ struct landlock_ruleset {
  			 * layers are set once and never changed for the
  			 * lifetime of the ruleset.
  			 */
-			access_mask_t fs_access_masks[];
+			access_mask_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 +177,19 @@ static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset)
  		refcount_inc(&ruleset->usage);
  }

+/* A helper function to set a filesystem mask. */
+static inline void
+landlock_set_fs_access_mask(struct landlock_ruleset *ruleset,
+			    const access_mask_t access_maskset, u16 mask_level)
+{
+	ruleset->access_masks[mask_level] = access_maskset;
+}
+
+/* A helper function to get a filesystem mask. */
+static inline u32

You need to use access_mask_t everywhere, including here.

+landlock_get_fs_access_mask(const struct landlock_ruleset *ruleset,
+			    u16 mask_level)
+{
+	return ruleset->access_masks[mask_level];
+}
  #endif /* _SECURITY_LANDLOCK_RULESET_H */
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 735a0865ea11..5836736ce9d7 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -346,10 +346,11 @@ 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]) {
+	if ((path_beneath_attr.allowed_access |
+	     landlock_get_fs_access_mask(ruleset, 0)) !=
+	    landlock_get_fs_access_mask(ruleset, 0)) {
  		err = -EINVAL;
  		goto out_put_ruleset;
  	}
--
2.25.1

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