All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Mickaël Salaün" <mic@digikod.net>
To: James Morris <jmorris@namei.org>, "Serge E . Hallyn" <serge@hallyn.com>
Cc: "Mickaël Salaün" <mic@digikod.net>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Jann Horn" <jannh@google.com>,
	"John Johansen" <john.johansen@canonical.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Konstantin Meskhidze" <konstantin.meskhidze@huawei.com>,
	"Paul Moore" <paul@paul-moore.com>,
	"Shuah Khan" <shuah@kernel.org>,
	"Tetsuo Handa" <penguin-kernel@I-love.SAKURA.ne.jp>,
	linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org
Subject: [PATCH v3 03/12] landlock: Create find_rule() from unmask_layers()
Date: Fri,  6 May 2022 18:10:53 +0200	[thread overview]
Message-ID: <20220506161102.525323-4-mic@digikod.net> (raw)
In-Reply-To: <20220506161102.525323-1-mic@digikod.net>

This refactoring will be useful in a following commit.

Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20220506161102.525323-4-mic@digikod.net
---

Changes since v2:
* Format with clang-format and rebase.

Changes since v1:
* Add Reviewed-by: Paul Moore.
---
 security/landlock/fs.c | 41 ++++++++++++++++++++++++++++-------------
 1 file changed, 28 insertions(+), 13 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index f48c0a3b1e75..20953bff8fd5 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -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;
-- 
2.35.1


  parent reply	other threads:[~2022-05-06 16:10 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-06 16:10 [PATCH v3 00/12] Landlock: file linking and renaming support Mickaël Salaün
2022-05-06 16:10 ` [PATCH v3 01/12] landlock: Define access_mask_t to enforce a consistent access mask size Mickaël Salaün
2022-05-06 16:10 ` [PATCH v3 02/12] landlock: Reduce the maximum number of layers to 16 Mickaël Salaün
2022-05-06 16:10 ` Mickaël Salaün [this message]
2022-05-06 16:10 ` [PATCH v3 04/12] landlock: Fix same-layer rule unions Mickaël Salaün
2022-05-06 16:10 ` [PATCH v3 05/12] landlock: Move filesystem helpers and add a new one Mickaël Salaün
2022-05-06 16:10 ` [PATCH v3 06/12] LSM: Remove double path_rename hook calls for RENAME_EXCHANGE Mickaël Salaün
2022-05-06 16:10 ` [PATCH v3 07/12] landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER Mickaël Salaün
2022-05-06 16:10 ` [PATCH v3 08/12] selftests/landlock: Add 11 new test suites dedicated to file reparenting Mickaël Salaün
2022-05-06 16:10 ` [PATCH v3 09/12] samples/landlock: Add support for " Mickaël Salaün
2022-05-06 16:11 ` [PATCH v3 10/12] landlock: Document LANDLOCK_ACCESS_FS_REFER and ABI versioning Mickaël Salaün
2022-05-06 16:11 ` [PATCH v3 11/12] landlock: Document good practices about filesystem policies Mickaël Salaün
2022-05-06 16:11 ` [PATCH v3 12/12] landlock: Add design choices documentation for filesystem access rights Mickaël Salaün
2022-05-06 16:31 ` [PATCH v3 00/12] Landlock: file linking and renaming support Mickaël Salaün

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220506161102.525323-4-mic@digikod.net \
    --to=mic@digikod.net \
    --cc=jannh@google.com \
    --cc=jmorris@namei.org \
    --cc=john.johansen@canonical.com \
    --cc=keescook@chromium.org \
    --cc=konstantin.meskhidze@huawei.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=paul@paul-moore.com \
    --cc=penguin-kernel@I-love.SAKURA.ne.jp \
    --cc=serge@hallyn.com \
    --cc=shuah@kernel.org \
    --cc=viro@zeniv.linux.org.uk \
    --subject='Re: [PATCH v3 03/12] landlock: Create find_rule() from unmask_layers()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.