tree 2642f95194a059307799c1e986a854f1545ec244
parent 62325883da2f537ae3630ba7055fb61e1f3b64cf
author Stephen McGruer <smcgruer@google.com> 1446238039 -0400
committer Stephen McGruer <smcgruer@google.com> 1446393391 -0500

Make uClibc (mostly) compatible with the Chromium setuid sandbox (b/24530000)

When in setuid mode, Chromium needs dlopen() to not call into open(),
close(), etc, as these will fail. It assumes instead that the libc will
cache loaded libraries by libname and return early if they match. This
patch adds that behavior to uClibc. For safety, I deal only with
absolute filepaths, since this avoids any concerns about false-positives
from relative filepaths.

There could still be a false-positive match if you did (pseudo-code);

dlopen("/libfoo.so");
move("/libbar.so", "/libfoo.so"); // overwrite libfoo.so
dlopen("/libfoo.so");

But that fails my three basic checks of:

  1. We have a read-only filesystem so it can't really happen.
  2. It fails under glibc anyway (they cache on filename!)
  3. It's insane, and you shouldn't be doing that.

Change-Id: I77e4c0084f3d669b8134f0e08c9211066dc0ebf2