[PATCH 15/28] security: Introduce inode_post_removexattr hook

[Roberto Sassu <roberto.sassu@xxxxxxxxxxxxxxx>]

From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>

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

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
 fs/xattr.c                    |  1 +
 include/linux/lsm_hook_defs.h |  2 ++
 include/linux/security.h      |  5 +++++
 security/security.c           | 14 ++++++++++++++
 4 files changed, 22 insertions(+)

diff --git a/fs/xattr.c b/fs/xattr.c
index 14a7eb3c8fa..10c959d9fc6 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -534,6 +534,7 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap,
 
 	if (!error) {
 		fsnotify_xattr(dentry);
+		security_inode_post_removexattr(dentry, name);
 		evm_inode_post_removexattr(dentry, name);
 	}
 
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index eedefbcdde3..2ae5224d967 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -147,6 +147,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
 LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
 LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name)
+LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
+	 const char *name)
 LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
 LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
diff --git a/include/linux/security.h b/include/linux/security.h
index 64224216f6c..b511f608958 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -373,6 +373,7 @@ int security_inode_getxattr(struct dentry *dentry, const char *name);
 int security_inode_listxattr(struct dentry *dentry);
 int security_inode_removexattr(struct mnt_idmap *idmap,
 			       struct dentry *dentry, const char *name);
+void security_inode_post_removexattr(struct dentry *dentry, const char *name);
 int security_inode_need_killpriv(struct dentry *dentry);
 int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
 int security_inode_getsecurity(struct mnt_idmap *idmap,
@@ -918,6 +919,10 @@ static inline int security_inode_removexattr(struct mnt_idmap *idmap,
 	return cap_inode_removexattr(idmap, dentry, name);
 }
 
+static inline void security_inode_post_removexattr(struct dentry *dentry,
+						   const char *name)
+{ }
+
 static inline int security_inode_need_killpriv(struct dentry *dentry)
 {
 	return cap_inode_need_killpriv(dentry);
diff --git a/security/security.c b/security/security.c
index 2dbf225f5d8..6bf4a92db94 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2404,6 +2404,20 @@ int security_inode_removexattr(struct mnt_idmap *idmap,
 	return evm_inode_removexattr(idmap, dentry, name);
 }
 
+/**
+ * security_inode_post_removexattr() - Update the inode after a removexattr op
+ * @dentry: file
+ * @name: xattr name
+ *
+ * Update the inode after a successful removexattr operation.
+ */
+void security_inode_post_removexattr(struct dentry *dentry, const char *name)
+{
+	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+		return;
+	call_void_hook(inode_post_removexattr, dentry, name);
+}
+
 /**
  * security_inode_need_killpriv() - Check if security_inode_killpriv() required
  * @dentry: associated dentry
-- 
2.25.1