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[v10,16/25] security: Introduce inode_post_set_acl hook

Message ID 20240215103113.2369171-17-roberto.sassu@huaweicloud.com (mailing list archive)
State New
Headers show
Series security: Move IMA and EVM to the LSM infrastructure | expand

Commit Message

Roberto Sassu Feb. 15, 2024, 10:31 a.m. UTC 
From: Roberto Sassu <roberto.sassu@huawei.com>

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

At inode_set_acl hook, EVM verifies the file's existing HMAC value. At
inode_post_set_acl, EVM re-calculates the file's HMAC based on the modified
POSIX ACL and other file metadata.

Other LSMs could similarly take some action after successful POSIX ACL
change.

The new hook cannot return an error and cannot cause the operation to be
reverted.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Christian Brauner <brauner@kernel.org>
---
 fs/posix_acl.c                |  1 +
 include/linux/lsm_hook_defs.h |  2 ++
 include/linux/security.h      |  7 +++++++
 security/security.c           | 17 +++++++++++++++++
 4 files changed, 27 insertions(+)
diff mbox series

Patch

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index e1af20893ebe..7556ee9f8a51 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -1137,6 +1137,7 @@  int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		error = -EIO;
 	if (!error) {
 		fsnotify_xattr(dentry);
+		security_inode_post_set_acl(dentry, acl_name, kacl);
 		evm_inode_post_set_acl(dentry, acl_name, kacl);
 	}
 
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 87f60b47dfca..b0125c99f80a 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -157,6 +157,8 @@  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(void, LSM_RET_VOID, inode_post_set_acl, struct dentry *dentry,
+	 const char *acl_name, struct posix_acl *kacl)
 LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *acl_name)
 LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap,
diff --git a/include/linux/security.h b/include/linux/security.h
index 1cb604282617..c372797e1617 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -372,6 +372,8 @@  int security_inode_setxattr(struct mnt_idmap *idmap,
 int security_inode_set_acl(struct mnt_idmap *idmap,
 			   struct dentry *dentry, const char *acl_name,
 			   struct posix_acl *kacl);
+void security_inode_post_set_acl(struct dentry *dentry, const char *acl_name,
+				 struct posix_acl *kacl);
 int security_inode_get_acl(struct mnt_idmap *idmap,
 			   struct dentry *dentry, const char *acl_name);
 int security_inode_remove_acl(struct mnt_idmap *idmap,
@@ -915,6 +917,11 @@  static inline int security_inode_set_acl(struct mnt_idmap *idmap,
 	return 0;
 }
 
+static inline void security_inode_post_set_acl(struct dentry *dentry,
+					       const char *acl_name,
+					       struct posix_acl *kacl)
+{ }
+
 static inline int security_inode_get_acl(struct mnt_idmap *idmap,
 					 struct dentry *dentry,
 					 const char *acl_name)
diff --git a/security/security.c b/security/security.c
index 59d49e5c2671..f7df58bd5f13 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2351,6 +2351,23 @@  int security_inode_set_acl(struct mnt_idmap *idmap,
 	return evm_inode_set_acl(idmap, dentry, acl_name, kacl);
 }
 
+/**
+ * security_inode_post_set_acl() - Update inode security from posix acls set
+ * @dentry: file
+ * @acl_name: acl name
+ * @kacl: acl struct
+ *
+ * Update inode security data after successfully setting posix acls on @dentry.
+ * The posix acls in @kacl are identified by @acl_name.
+ */
+void security_inode_post_set_acl(struct dentry *dentry, const char *acl_name,
+				 struct posix_acl *kacl)
+{
+	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+		return;
+	call_void_hook(inode_post_set_acl, dentry, acl_name, kacl);
+}
+
 /**
  * security_inode_get_acl() - Check if reading posix acls is allowed
  * @idmap: idmap of the mount