* Djalal Harouni <tixxdz@xxxxxxxxxx> wrote: > > Regardless, glibc uses /proc/self/maps, which would be fine here, right? > > I did not touch /proc/self/maps and others, but I'm planning to fix them > if this solution is accepted. > > I'll do the same thing as in /proc/*/stat for maps, let it be 0444, and > try to delay the check to ->read(). So during ->read() perform > ptrace_may_access() on currenct's cred and process_allow_access() on > file's opener cred. This should work. Aren't read() time checks fundamentally unrobust? We generally don't do locking on read()s, so such checks - in the general case - are pretty racy. Now procfs might be special, as by its nature of a pseudofilesystem it's far more atomic than other filesystems, but still IMHO it's a lot more robust security design wise to revoke access to objects you should not have a reference to when a security boundary is crossed, than letting stuff leak through and sprinking all the potential cases that may leak information with permission checks ... It's also probably faster: security boundary crossings are relatively rare slowpaths, while read()s are much more common... So please first get consensus on this fundamental design question before spreading your solution to more areas. Thanks, Ingo -- 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
