[PATCH 19/28] security: Introduce inode_post_create_tmpfile hook

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>

In preparation for moving IMA and EVM to the LSM infrastructure, introduce
the inode_post_create_tmpfile hook.

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
 fs/namei.c                    |  1 +
 include/linux/lsm_hook_defs.h |  2 ++
 include/linux/security.h      |  8 ++++++++
 security/security.c           | 18 ++++++++++++++++++
 4 files changed, 29 insertions(+)

diff --git a/fs/namei.c b/fs/namei.c
index 3f2747521d3..8c4fdfd81d4 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3624,6 +3624,7 @@ static int vfs_tmpfile(struct mnt_idmap *idmap,
 		inode->i_state |= I_LINKABLE;
 		spin_unlock(&inode->i_lock);
 	}
+	security_inode_post_create_tmpfile(idmap, dir, file_dentry(file), mode);
 	ima_post_create_tmpfile(idmap, dir, file_dentry(file), mode);
 	return 0;
 }
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 32c801a3ea2..5dc2a7c3d9a 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -120,6 +120,8 @@ LSM_HOOK(int, 0, inode_init_security_anon, struct inode *inode,
 	 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,
+	 struct inode *dir, struct dentry *dentry, umode_t mode)
 LSM_HOOK(int, 0, inode_link, struct dentry *old_dentry, struct inode *dir,
 	 struct dentry *new_dentry)
 LSM_HOOK(int, 0, inode_unlink, struct inode *dir, struct dentry *dentry)
diff --git a/include/linux/security.h b/include/linux/security.h
index fb6e9d434c6..b3e201404dc 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -337,6 +337,9 @@ int security_inode_init_security_anon(struct inode *inode,
 				      const struct qstr *name,
 				      const struct inode *context_inode);
 int security_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode);
+void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
+					struct inode *dir,
+					struct dentry *dentry, umode_t mode);
 int security_inode_link(struct dentry *old_dentry, struct inode *dir,
 			 struct dentry *new_dentry);
 int security_inode_unlink(struct inode *dir, struct dentry *dentry);
@@ -787,6 +790,11 @@ static inline int security_inode_create(struct inode *dir,
 	return 0;
 }
 
+static inline void
+security_inode_post_create_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
+				   struct dentry *dentry, umode_t mode)
+{ }
+
 static inline int security_inode_link(struct dentry *old_dentry,
 				       struct inode *dir,
 				       struct dentry *new_dentry)
diff --git a/security/security.c b/security/security.c
index f5f367e2064..8883082b686 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1971,6 +1971,24 @@ int security_inode_create(struct inode *dir, struct dentry *dentry,
 }
 EXPORT_SYMBOL_GPL(security_inode_create);
 
+/**
+ * security_inode_post_create_tmpfile() - Update inode sec after tmpfile created
+ * @idmap: idmap of the mount
+ * @dir: the inode of the base directory
+ * @dentry: the dentry of the new tmpfile
+ * @mode: the mode of the new tmpfile
+ *
+ * Update inode security field after a tmpfile has been created.
+ */
+void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
+					struct inode *dir,
+					struct dentry *dentry, umode_t mode)
+{
+	if (unlikely(IS_PRIVATE(dir)))
+		return;
+	call_void_hook(inode_post_create_tmpfile, idmap, dir, dentry, mode);
+}
+
 /**
  * security_inode_link() - Check if creating a hard link is allowed
  * @old_dentry: existing file
-- 
2.25.1