On Thu, Sep 26, 2013 at 03:43:24PM -0500, Kees Cook wrote: > On Wed, Sep 25, 2013 at 3:14 PM, Djalal Harouni <tixxdz@xxxxxxxxxx> wrote: > > The /proc/*/stack contains sensitive information and currently its mode > > is 0444. Change this to 0400 so the VFS will be able to block > > unprivileged processes to get file descriptors on arbitrary privileged > > /proc/*/stack files. > > > > The /proc/*/stack is a /procfs ONE file that shares the same ->open() > > file operation with other ONE files. Doing a ptrace_may_access() check > > during open() might break userspace from accessing other ONE files > > like /proc/*/stat and /proc/*/statm. > > > > Therfore make it 0400 for now, and improve its check during ->read() > > in the next following patch. > > > > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > > Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> > > Signed-off-by: Djalal Harouni <tixxdz@xxxxxxxxxx> > > While the rest of the series is being discussed, I think it would be > nice to at least get this into the tree. Fixing this reduces which > processes are exposed to ASLR leaks. The rest of the series closes the > remaining holes. > > I would if it would be valuable adding a test for the identified leak > conditions to some test suite? LTP perhaps? I'm not familiar with LTP, but I guess a small program that perform I/O redirection and execve a suid-exec will do it? I'll try to add code comment in fs/proc/base.c > -Kees > > -- > Kees Cook > Chrome OS Security -- Djalal Harouni http://opendz.org -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
