Hi Roberto,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on security/next-testing]
[also build test ERROR on integrity/next-integrity linus/master v5.12-rc6 next-20210407]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Roberto-Sassu/evm-Improve-usability-of-portable-signatures/20210407-185747
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git next-testing
config: s390-randconfig-r034-20210407 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project c060945b23a1c54d4b2a053ff4b093a2277b303d)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        # https://github.com/0day-ci/linux/commit/1bdae98f0b81260a925cf7acf785dc10bb7787fe
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Roberto-Sassu/evm-Improve-usability-of-portable-signatures/20210407-185747
        git checkout 1bdae98f0b81260a925cf7acf785dc10bb7787fe
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> security/integrity/evm/evm_main.c:365:7: error: implicit declaration of function 'posix_acl_update_mode' [-Werror,-Wimplicit-function-declaration]
           rc = posix_acl_update_mode(mnt_userns, inode, &mode, &acl_res);
                ^
   1 error generated.


vim +/posix_acl_update_mode +365 security/integrity/evm/evm_main.c

   331	
   332	/*
   333	 * evm_xattr_acl_change - check if passed ACL changes the inode mode
   334	 * @mnt_userns: user namespace of the idmapped mount
   335	 * @dentry: pointer to the affected dentry
   336	 * @xattr_name: requested xattr
   337	 * @xattr_value: requested xattr value
   338	 * @xattr_value_len: requested xattr value length
   339	 *
   340	 * Check if passed ACL changes the inode mode, which is protected by EVM.
   341	 *
   342	 * Returns 1 if passed ACL causes inode mode change, 0 otherwise.
   343	 */
   344	static int evm_xattr_acl_change(struct user_namespace *mnt_userns,
   345					struct dentry *dentry, const char *xattr_name,
   346					const void *xattr_value, size_t xattr_value_len)
   347	{
   348		umode_t mode;
   349		struct posix_acl *acl = NULL, *acl_res;
   350		struct inode *inode = d_backing_inode(dentry);
   351		int rc;
   352	
   353		/* user_ns is not relevant here, ACL_USER/ACL_GROUP don't have impact
   354		 * on the inode mode (see posix_acl_equiv_mode()).
   355		 */
   356		acl = posix_acl_from_xattr(&init_user_ns, xattr_value, xattr_value_len);
   357		if (IS_ERR_OR_NULL(acl))
   358			return 1;
   359	
   360		acl_res = acl;
   361		/* Passing mnt_userns is necessary to correctly determine the GID in
   362		 * an idmapped mount, as the GID is used to clear the setgid bit in
   363		 * the inode mode.
   364		 */
 > 365		rc = posix_acl_update_mode(mnt_userns, inode, &mode, &acl_res);
   366	
   367		posix_acl_release(acl);
   368	
   369		if (rc)
   370			return 1;
   371	
   372		if (inode->i_mode != mode)
   373			return 1;
   374	
   375		return 0;
   376	}
   377	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org