Re: [PATCH v1 2/2] io_uring,audit: do not log IORING_OP_*GETXATTR

On Fri, Jan 27, 2023 at 6:01 PM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > On 2023-01-27 17:43, Paul Moore wrote: > > On Fri, Jan 27, 2023 at 12:24 PM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > > Getting XATTRs is not particularly interesting security-wise. > > > > > > Suggested-by: Steve Grubb <sgrubb(a)redhat.com&gt; > > > Fixes: a56834e0fafe ("io_uring: add fgetxattr and getxattr support") > > > Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > > > --- > > > io_uring/opdef.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > Depending on your security policy, fetching file data, including > > xattrs, can be interesting from a security perspective. As an > > example, look at the SELinux file/getattr permission. > > > > https://github.com/SELinuxProject/selinux-notebook/blob/main/src/object_c... > > The intent here is to lessen the impact of audit operations. Read and > Write were explicitly removed from io_uring auditing due to performance > concerns coupled with the denial of service implications from sheer > volume of records making other messages harder to locate. Those > operations are still possible for syscall auditing but they are strongly > discouraged for normal use. We need to balance security needs and performance needs. You are correct that general read() and write() operations are not audited, and generally not checked from a LSM perspective as the auditing and access control happens at open() time instead (access to fds is revalidated when they are passed). However, in the case of getxattr and fgetxattr, these are not normal file read operations, and do not go through the same code path in the kernel; there is a reason why we have xattr_permission() and security_inode_getxattr(). We need to continue to audit IORING_OP_FGETXATTR and IORING_OP_GETXATTR.

paul-moore.com