From: KP Singh kpsingh@google.com
[ Upstream commit 23e390cdbe6f85827a43d38f9288dcd3066fa376 ]
inode_copy_up_xattr returns 0 to indicate the acceptance of the xattr and 1 to reject it. If the LSM does not know about the xattr, it's expected to return -EOPNOTSUPP, which is the correct default value for this hook. BPF LSM, currently, uses 0 as the default value and thereby falsely allows all overlay fs xattributes to be copied up.
The iteration logic is also updated from the "bail-on-fail" call_int_hook to continue on the non-decisive -EOPNOTSUPP and bail out on other values.
Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks") Signed-off-by: KP Singh kpsingh@google.com Signed-off-by: James Morris jmorris@namei.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/lsm_hook_defs.h | 2 +- security/security.c | 17 ++++++++++++++++- 2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 5616b2567aa7f..c2d073c49bf8a 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -149,7 +149,7 @@ LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer, size_t buffer_size) LSM_HOOK(void, LSM_RET_VOID, inode_getsecid, struct inode *inode, u32 *secid) LSM_HOOK(int, 0, inode_copy_up, struct dentry *src, struct cred **new) -LSM_HOOK(int, 0, inode_copy_up_xattr, const char *name) +LSM_HOOK(int, -EOPNOTSUPP, inode_copy_up_xattr, const char *name) LSM_HOOK(int, 0, kernfs_init_security, struct kernfs_node *kn_dir, struct kernfs_node *kn) LSM_HOOK(int, 0, file_permission, struct file *file, int mask) diff --git a/security/security.c b/security/security.c index 51de970fbb1ed..8b4d342ade5e1 100644 --- a/security/security.c +++ b/security/security.c @@ -1409,7 +1409,22 @@ EXPORT_SYMBOL(security_inode_copy_up);
int security_inode_copy_up_xattr(const char *name) { - return call_int_hook(inode_copy_up_xattr, -EOPNOTSUPP, name); + struct security_hook_list *hp; + int rc; + + /* + * The implementation can return 0 (accept the xattr), 1 (discard the + * xattr), -EOPNOTSUPP if it does not know anything about the xattr or + * any other error code incase of an error. + */ + hlist_for_each_entry(hp, + &security_hook_heads.inode_copy_up_xattr, list) { + rc = hp->hook.inode_copy_up_xattr(name); + if (rc != LSM_RET_DEFAULT(inode_copy_up_xattr)) + return rc; + } + + return LSM_RET_DEFAULT(inode_copy_up_xattr); } EXPORT_SYMBOL(security_inode_copy_up_xattr);