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ovl: update S_ISGID when setting posix ACLs

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This change fixes xfstest generic/375, which failed to clear the
setgid bit in the following test case on overlayfs:

  touch $testfile
  chown 100:100 $testfile
  chmod 2755 $testfile
  _runas -u 100 -g 101 -- setfacl -m u::rwx,g::rwx,o::rwx $testfile

Reported-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Amir Goldstein <amir73il@gmail.com>
Fixes: d837a49bd5 ("ovl: fix POSIX ACL setting")
Cc: <stable@vger.kernel.org> # v4.8
This commit is contained in:
Miklos Szeredi 2016-10-31 14:42:14 +01:00
parent a909d3e636
commit fd3220d37b
1 changed files with 15 additions and 0 deletions
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15
fs/overlayfs/super.c
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@ -1037,6 +1037,21 @@ ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
posix_acl_release(acl);
/*
* Check if sgid bit needs to be cleared (actual setacl operation will
* be done with mounter's capabilities and so that won't do it for us).
*/
if (unlikely(inode->i_mode & S_ISGID) &&
handler->flags == ACL_TYPE_ACCESS &&
!in_group_p(inode->i_gid) &&
!capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
err = ovl_setattr(dentry, &iattr);
if (err)
return err;
}
err = ovl_xattr_set(dentry, handler->name, value, size, flags);
if (!err)
ovl_copyattr(ovl_inode_real(inode, NULL), inode);