1 files changed, 188 insertions, 0 deletions
diff --git a/security/landlock/fs.h b/security/landlock/fs.h
new file mode 100644
index 000000000..50b3ddb8a
--- /dev/null
+++ b/security/landlock/fs.h
@@ -0,0 +1,188 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock - Filesystem management and hooks
+ *
+ * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2020 ANSSI
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#ifndef _SECURITY_LANDLOCK_FS_H
+#define _SECURITY_LANDLOCK_FS_H
+
+#include <linux/build_bug.h>
+#include <linux/cleanup.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/rcupdate.h>
+
+#include "access.h"
+#include "cred.h"
+#include "ruleset.h"
+#include "setup.h"
+
+DEFINE_FREE(__putname, char *, if (_T) __putname(_T))
+
+/**
+ * struct landlock_inode_security - Inode security blob
+ *
+ * Enable to reference a &struct landlock_object tied to an inode (i.e.
+ * underlying object).
+ */
+struct landlock_inode_security {
+	/**
+	 * @object: Weak pointer to an allocated object.  All assignments of a
+	 * new object are protected by the underlying inode->i_lock.  However,
+	 * atomically disassociating @object from the inode is only protected
+	 * by @object->lock, from the time @object's usage refcount drops to
+	 * zero to the time this pointer is nulled out (cf. release_inode() and
+	 * hook_sb_delete()).  Indeed, such disassociation doesn't require
+	 * inode->i_lock thanks to the careful rcu_access_pointer() check
+	 * performed by get_inode_object().
+	 */
+	struct landlock_object __rcu *object;
+};
+
+/**
+ * struct landlock_file_security - File security blob
+ *
+ * This information is populated when opening a file in hook_file_open, and
+ * tracks the relevant Landlock access rights that were available at the time
+ * of opening the file. Other LSM hooks use these rights in order to authorize
+ * operations on already opened files.
+ */
+struct landlock_file_security {
+	/**
+	 * @allowed_access: Access rights that were available at the time of
+	 * opening the file. This is not necessarily the full set of access
+	 * rights available at that time, but it's the necessary subset as
+	 * needed to authorize later operations on the open file.
+	 */
+	access_mask_t allowed_access;
+
+#ifdef CONFIG_SECURITY_LANDLOCK_LOG
+	/**
+	 * @deny_masks: Domain layer levels that deny an optional access (see
+	 * _LANDLOCK_ACCESS_FS_OPTIONAL).
+	 */
+	deny_masks_t deny_masks;
+	/**
+	 * @quiet_optional_accesses: Stores which optional accesses are covered
+	 * by quiet rules within the layer referred to in deny_masks, one access
+	 * per bit.  Does not take into account whether the quiet access bits
+	 * are actually set in the layer's corresponding landlock_hierarchy.
+	 */
+	optional_access_t quiet_optional_accesses;
+	/**
+	 * @fown_layer: Layer level of @fown_subject->domain with
+	 * LANDLOCK_SCOPE_SIGNAL.
+	 */
+	u8 fown_layer;
+#endif /* CONFIG_SECURITY_LANDLOCK_LOG */
+
+	/**
+	 * @fown_subject: Landlock credential of the task that set the PID that
+	 * may receive a signal e.g., SIGURG when writing MSG_OOB to the
+	 * related socket.  This pointer is protected by the related
+	 * file->f_owner->lock, as for fown_struct's members: pid, uid, and
+	 * euid.
+	 */
+	struct landlock_cred_security fown_subject;
+	/**
+	 * @fown_tg: Thread group of the task that set the file owner, pinned
+	 * while @fown_subject holds a domain.  It lets
+	 * hook_file_send_sigiotask() always allow a SIGIO delivered to the
+	 * owner's own process -- e.g. the thread-group leader reached through a
+	 * process-group owner -- matching the same-process exemption of
+	 * hook_task_kill().  NULL when no domain is recorded.  Protected by
+	 * file->f_owner->lock, like @fown_subject.
+	 */
+	struct pid *fown_tg;
+};
+
+#ifdef CONFIG_SECURITY_LANDLOCK_LOG
+
+/* Makes sure all layers can be identified. */
+/* clang-format off */
+static_assert((typeof_member(struct landlock_file_security, fown_layer))~0 >=
+	      LANDLOCK_MAX_NUM_LAYERS);
+/* clang-format on */
+
+/*
+ * Make sure quiet_optional_accesses has enough bits to cover all optional
+ * accesses.
+ */
+static_assert(BITS_PER_TYPE(typeof_member(struct landlock_file_security,
+					  quiet_optional_accesses)) >=
+	      HWEIGHT(_LANDLOCK_ACCESS_FS_OPTIONAL));
+
+#endif /* CONFIG_SECURITY_LANDLOCK_LOG */
+
+/**
+ * struct landlock_superblock_security - Superblock security blob
+ *
+ * Enable hook_sb_delete() to wait for concurrent calls to release_inode().
+ */
+struct landlock_superblock_security {
+	/**
+	 * @inode_refs: Number of pending inodes (from this superblock) that
+	 * are being released by release_inode().
+	 * Cf. struct super_block->s_fsnotify_inode_refs .
+	 */
+	atomic_long_t inode_refs;
+};
+
+static inline struct landlock_file_security *
+landlock_file(const struct file *const file)
+{
+	return file->f_security + landlock_blob_sizes.lbs_file;
+}
+
+static inline struct landlock_inode_security *
+landlock_inode(const struct inode *const inode)
+{
+	return inode->i_security + landlock_blob_sizes.lbs_inode;
+}
+
+static inline struct landlock_superblock_security *
+landlock_superblock(const struct super_block *const superblock)
+{
+	return superblock->s_security + landlock_blob_sizes.lbs_superblock;
+}
+
+__init void landlock_add_fs_hooks(void);
+
+int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
+			    const struct path *const path,
+			    access_mask_t access_hierarchy, const u32 flags);
+
+/**
+ * resolve_path_for_trace - Resolve a path for tracepoint display
+ *
+ * @path: The path to resolve.
+ * @buf: A buffer of at least PATH_MAX bytes for the resolved path.
+ *
+ * Uses d_absolute_path() to produce a namespace-independent absolute path,
+ * unlike d_path() which resolves relative to the process's chroot.  This
+ * ensures trace output is deterministic regardless of the tracer's mount
+ * namespace.
+ *
+ * Return: A pointer into @buf with the resolved path, or an error string
+ * ("<too_long>", "<unreachable>").
+ */
+static inline const char *resolve_path_for_trace(const struct path *path,
+						 char *buf)
+{
+	const char *p;
+
+	p = d_absolute_path(path, buf, PATH_MAX);
+	if (!IS_ERR_OR_NULL(p))
+		return p;
+
+	if (PTR_ERR(p) == -ENAMETOOLONG)
+		return "<too_long>";
+
+	return "<unreachable>";
+}
+
+#endif /* _SECURITY_LANDLOCK_FS_H */