linux-kernel - [RFC PATCH 1/2] lsm: add type to security_inode_init_security

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Message-ID: <20250807075647.755848-1-tweek@google.com>
Date: Thu,  7 Aug 2025 17:56:46 +1000
From: "Thiébaud Weksteen" <tweek@...gle.com>
To: Paul Moore <paul@...l-moore.com>, James Morris <jmorris@...ei.org>, 
	Stephen Smalley <stephen.smalley.work@...il.com>, Hugh Dickins <hughd@...gle.com>, 
	Jeff Vander Stoep <jeffv@...gle.com>, Nick Kralevich <nnk@...gle.com>, Jeff Xu <jeffxu@...gle.com>
Cc: "Thiébaud Weksteen" <tweek@...gle.com>, linux-kernel@...r.kernel.org, 
	linux-security-module@...r.kernel.org, selinux@...r.kernel.org
Subject: [RFC PATCH 1/2] lsm: add type to security_inode_init_security_anon

Introduce a new enum (lsm_anon_inode_id) to identify the type of
anonymous inode being created. This enum is passed down to the
security_inode_init_security_anon LSM hook.

Signed-off-by: Thiébaud Weksteen <tweek@...gle.com>
---
 fs/anon_inodes.c              | 5 +++--
 include/linux/lsm_hook_defs.h | 3 ++-
 include/linux/security.h      | 8 ++++++++
 security/security.c           | 4 +++-
 security/selinux/hooks.c      | 1 +
 5 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 1d847a939f29..9a2f09808f86 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -21,6 +21,7 @@
 #include <linux/magic.h>
 #include <linux/anon_inodes.h>
 #include <linux/pseudo_fs.h>
+#include <linux/security.h>
 
 #include <linux/uaccess.h>
 
@@ -121,8 +122,8 @@ struct inode *anon_inode_make_secure_inode(struct super_block *sb, const char *n
 		return inode;
 	inode->i_flags &= ~S_PRIVATE;
 	inode->i_op = &anon_inode_operations;
-	error =	security_inode_init_security_anon(inode, &QSTR(name),
-						  context_inode);
+	error = security_inode_init_security_anon(inode, LSM_ANON_INODE_GENERIC,
+						  &QSTR(name), context_inode);
 	if (error) {
 		iput(inode);
 		return ERR_PTR(error);
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index fd11fffdd3c3..1634f41f7a3c 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -119,7 +119,8 @@ LSM_HOOK(int, -EOPNOTSUPP, inode_init_security, struct inode *inode,
 	 struct inode *dir, const struct qstr *qstr, struct xattr *xattrs,
 	 int *xattr_count)
 LSM_HOOK(int, 0, inode_init_security_anon, struct inode *inode,
-	 const struct qstr *name, const struct inode *context_inode)
+	 enum lsm_anon_inode_id type, const struct qstr *name,
+	 const struct inode *context_inode)
 LSM_HOOK(int, 0, inode_create, struct inode *dir, struct dentry *dentry,
 	 umode_t mode)
 LSM_HOOK(void, LSM_RET_VOID, inode_post_create_tmpfile, struct mnt_idmap *idmap,
diff --git a/include/linux/security.h b/include/linux/security.h
index 521bcb5b9717..98a97b8a1093 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -263,6 +263,12 @@ struct request_sock;
 #define LSM_UNSAFE_PTRACE	2
 #define LSM_UNSAFE_NO_NEW_PRIVS	4
 
+/* anon_inode types */
+enum lsm_anon_inode_id {
+	LSM_ANON_INODE_GENERIC,
+	LSM_ANON_INODE_MEMFD
+};
+
 #ifdef CONFIG_MMU
 extern int mmap_min_addr_handler(const struct ctl_table *table, int write,
 				 void *buffer, size_t *lenp, loff_t *ppos);
@@ -402,6 +408,7 @@ int security_inode_init_security(struct inode *inode, struct inode *dir,
 				 const struct qstr *qstr,
 				 initxattrs initxattrs, void *fs_data);
 int security_inode_init_security_anon(struct inode *inode,
+				      enum lsm_anon_inode_id type,
 				      const struct qstr *name,
 				      const struct inode *context_inode);
 int security_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode);
@@ -889,6 +896,7 @@ static inline int security_inode_init_security(struct inode *inode,
 }
 
 static inline int security_inode_init_security_anon(struct inode *inode,
+						    enum lsm_anon_inode_id type,
 						    const struct qstr *name,
 						    const struct inode *context_inode)
 {
diff --git a/security/security.c b/security/security.c
index ad163f06bf7a..09aa858819a2 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1861,6 +1861,7 @@ EXPORT_SYMBOL(security_inode_init_security);
 /**
  * security_inode_init_security_anon() - Initialize an anonymous inode
  * @inode: the inode
+ * @type: the type of anonymous inode
  * @name: the anonymous inode class
  * @context_inode: an optional related inode
  *
@@ -1871,10 +1872,11 @@ EXPORT_SYMBOL(security_inode_init_security);
  * creation of this inode, or another -errno upon other errors.
  */
 int security_inode_init_security_anon(struct inode *inode,
+				      enum lsm_anon_inode_id type,
 				      const struct qstr *name,
 				      const struct inode *context_inode)
 {
-	return call_int_hook(inode_init_security_anon, inode, name,
+	return call_int_hook(inode_init_security_anon, inode, type, name,
 			     context_inode);
 }
 
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index c95a5874bf7d..8d36d5ebb6e5 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2967,6 +2967,7 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
 }
 
 static int selinux_inode_init_security_anon(struct inode *inode,
+					    enum lsm_anon_inode_id type,
 					    const struct qstr *name,
 					    const struct inode *context_inode)
 {
-- 
2.50.1.703.g449372360f-goog