linux-kernel - [PATCH -next] lsm: fix default return value for inode

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Date: Mon, 29 Apr 2024 19:46:36 +0800
From: felix <fuzhen5@...wei.com>
To: <paul@...l-moore.com>, <casey@...aufler-ca.com>,
	<roberto.sassu@...wei.com>, <stefanb@...ux.ibm.com>, <zohar@...ux.ibm.com>,
	<kamrankhadijadj@...il.com>, <andrii@...nel.org>, <omosnace@...hat.com>
CC: <linux-kernel@...r.kernel.org>, <bpf@...r.kernel.org>,
	<xiujianfeng@...wei.com>, <wangweiyang2@...wei.com>
Subject: [PATCH -next] lsm: fix default return value for inode_set(remove)xattr

From: Felix Fu <fuzhen5@...wei.com>

The return value of security_inode_set(remove)xattr should
be 1. If it return 0, cap_inode_setxattr would not be
executed when no lsm exist, which is not what we expected,
any user could set some security.* xattr for a file.

Before commit 260017f31a8c ("lsm: use default hook return
value in call_int_hook()") was approved, this issue would
still happened when lsm only include bpf, because bpf_lsm_
inode_setxattr return 0 by default which cause cap_inode_set
xattr to be not executed.

Fixes: 260017f31a8c ("lsm: use default hook return value in call_int_hook()")
Signed-off-by: Felix Fu <fuzhen5@...wei.com>
---
 include/linux/lsm_hook_defs.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index f804b76cde44..9c768b954264 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -144,14 +144,14 @@ LSM_HOOK(int, 0, inode_setattr, struct mnt_idmap *idmap, struct dentry *dentry,
 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,
+LSM_HOOK(int, 1, inode_setxattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name, const void *value,
 	 size_t size, int flags)
 LSM_HOOK(void, LSM_RET_VOID, inode_post_setxattr, struct dentry *dentry,
 	 const char *name, const void *value, size_t size, int flags)
 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,
+LSM_HOOK(int, 1, 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)
-- 
2.34.1