[PATCH 14/28] security: Introduce inode_post_setattr 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_setattr hook.

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
 fs/attr.c                     |  1 +
 include/linux/lsm_hook_defs.h |  2 ++
 include/linux/security.h      |  7 +++++++
 security/security.c           | 16 ++++++++++++++++
 4 files changed, 26 insertions(+)

diff --git a/fs/attr.c b/fs/attr.c
index da45cf01be6..343d6d62435 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -485,6 +485,7 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 
 	if (!error) {
 		fsnotify_change(dentry, ia_valid);
+		security_inode_post_setattr(idmap, dentry, ia_valid);
 		ima_inode_post_setattr(idmap, dentry, ia_valid);
 		evm_inode_post_setattr(idmap, dentry, ia_valid);
 	}
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 4372a6b2632..eedefbcdde3 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -135,6 +135,8 @@ LSM_HOOK(int, 0, inode_follow_link, struct dentry *dentry, struct inode *inode,
 LSM_HOOK(int, 0, inode_permission, struct inode *inode, int mask)
 LSM_HOOK(int, 0, inode_setattr, struct mnt_idmap *idmap, struct dentry *dentry,
 	 struct iattr *attr)
+LSM_HOOK(void, LSM_RET_VOID, inode_post_setattr, struct mnt_idmap *idmap,
+	 struct dentry *dentry, int ia_valid)
 LSM_HOOK(int, 0, inode_getattr, const struct path *path)
 LSM_HOOK(int, 0, inode_setxattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name, const void *value,
diff --git a/include/linux/security.h b/include/linux/security.h
index cd23221ce9e..64224216f6c 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -354,6 +354,8 @@ int security_inode_follow_link(struct dentry *dentry, struct inode *inode,
 int security_inode_permission(struct inode *inode, int mask);
 int security_inode_setattr(struct mnt_idmap *idmap,
 			   struct dentry *dentry, struct iattr *attr);
+void security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+				 int ia_valid);
 int security_inode_getattr(const struct path *path);
 int security_inode_setxattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry, const char *name,
@@ -855,6 +857,11 @@ static inline int security_inode_setattr(struct mnt_idmap *idmap,
 	return 0;
 }
 
+static inline void
+security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+			    int ia_valid)
+{ }
+
 static inline int security_inode_getattr(const struct path *path)
 {
 	return 0;
diff --git a/security/security.c b/security/security.c
index f7fe252e9d3..2dbf225f5d8 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2190,6 +2190,22 @@ int security_inode_getattr(const struct path *path)
 	return call_int_hook(inode_getattr, 0, path);
 }
 
+/**
+ * security_inode_post_setattr() - Update the inode after a setattr operation
+ * @idmap: idmap of the mount
+ * @dentry: file
+ * @ia_valid: file attributes set
+ *
+ * Update inode security field after successful setting file attributes.
+ */
+void security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+				 int ia_valid)
+{
+	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+		return;
+	call_void_hook(inode_post_setattr, idmap, dentry, ia_valid);
+}
+
 /**
  * security_inode_setxattr() - Check if setting file xattrs is allowed
  * @idmap: idmap of the mount
-- 
2.25.1