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WTF: patch "[PATCH] landlock: Create find_rule() from unmask_layers()" was seriously submitted to be applied to the 5.18-stable tree?

PATCH [email protected] 1 participant 1 message Jun 6, 2022

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Stable branch Security (LSM) Landlock security module
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The patch below was submitted to be applied to the 5.18-stable tree.

I fail to see how this patch meets the stable kernel rules as found at Documentation/process/stable-kernel-rules.rst.

I could be totally wrong, and if so, please respond to <[email protected]> and let me know why this patch should be applied. Otherwise, it is now dropped from my patch queues, never to be seen again.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2cd7cd6eed88b8383cfddce589afe9c0ae1d19b4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= <[email protected]>
Date: Fri, 6 May 2022 18:10:53 +0200
Subject: [PATCH] landlock: Create find_rule() from unmask_layers()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This refactoring will be useful in a following commit.

Reviewed-by Paul Moore <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Cc [email protected]
Signed-off-by Mickaël Salaün <[email protected]>
security/landlock/fs.c +28 -13
index f48c0a3b1e75..20953bff8fd5 100644
@@ -183,23 +183,36 @@ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
 
 /* Access-control management */
 
-static inline layer_mask_t
-unmask_layers(const struct landlock_ruleset *const domain,
-	      const struct path *const path, const access_mask_t access_request,
-	      layer_mask_t layer_mask)
+/*
+ * The lifetime of the returned rule is tied to @domain.
+ *
+ * Returns NULL if no rule is found or if @dentry is negative.
+ */
+static inline const struct landlock_rule *
+find_rule(const struct landlock_ruleset *const domain,
+	  const struct dentry *const dentry)
 {
 	const struct landlock_rule *rule;
 	const struct inode *inode;
-	size_t i;
 
-	if (d_is_negative(path->dentry))
-		/* Ignore nonexistent leafs. */
-		return layer_mask;
-	inode = d_backing_inode(path->dentry);
+	/* Ignores nonexistent leafs. */
+	if (d_is_negative(dentry))
+		return NULL;
+
+	inode = d_backing_inode(dentry);
 	rcu_read_lock();
 	rule = landlock_find_rule(
 		domain, rcu_dereference(landlock_inode(inode)->object));
 	rcu_read_unlock();
+	return rule;
+}
+
+static inline layer_mask_t unmask_layers(const struct landlock_rule *const rule,
+					 const access_mask_t access_request,
+					 layer_mask_t layer_mask)
+{
+	size_t layer_level;
+
 	if (!rule)
 		return layer_mask;
 

@@ -210,8 +223,9 @@ unmask_layers(const struct landlock_ruleset *const domain,
 	 * the remaining layers for each inode, from the first added layer to
 	 * the last one.
 	 */
-	for (i = 0; i < rule->num_layers; i++) {
-		const struct landlock_layer *const layer = &rule->layers[i];
+	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);
 
 		/* Checks that the layer grants access to the full request. */

@@ -269,8 +283,9 @@ static int check_access_path(const struct landlock_ruleset *const domain,
 	while (true) {
 		struct dentry *parent_dentry;
 
-		layer_mask = unmask_layers(domain, &walker_path, access_request,
-					   layer_mask);
+		layer_mask =
+			unmask_layers(find_rule(domain, walker_path.dentry),
+				      access_request, layer_mask);
 		if (layer_mask == 0) {
 			/* Stops when a rule from each layer grants access. */
 			allowed = true;