This reorganizes SandboxAssembler to stack up the policy rules and
traverse them in reverse order to build the filter DAG from tail to head
(i.e., starting with "deny all" and prepending allow and return-errno
rules). Thus, this code will continue to work (perhaps with minor
changes, such as to the NodePtr typedef) with future versions of the
Chromium sandbox code that don't allow mutating the filter program with
the JoinInstructions method.
Resolve the build failure caused by API changes
There are some changes in Audio APIs in Android version
21. Modifying the code to use the new APIs.
Change-Id: I24fdeb20f8f957d05fb6c0c317de0a6f0769c347
Resolve seccomp violation caused by syscall 256
Modify the filter to allow syscall 256 (set_tid_address).
Change-Id: I49461770c4c5e70bf68462d34321381b0b7ead0a
Specifically:
* SandboxCrash() uses internal Gecko interfaces, so stays in libxul.
* SandboxInfo moves to libxul from libmozsandbox, which no longer exists.
* Where libxul calls Set*Sandbox(), it uses weak symbols.
* Everything remains as it was on mobile.
This changes the interface so that the code which determines the flags
can live in one place, but checking the flags doesn't need to call into
another library.
Also removes the no-op wrappers for Set*Sandbox when disabled at build
time; nothing used them, one of them was unusable due to having the wrong
type, and all they really accomplish is allowing sloppiness with ifdefs
(which could hide actual mistakes).
This adds "hasSeccompBPF" for seccomp-bpf support; other "has" keys
will be added in the future (e.g., user namespaces).
This also adds "canSandboxContent" and "canSandboxMedia", which are
absent if the corresponding type of sandboxing isn't enabled at build
type (or is disabled with environment variables), and otherwise present
as a boolean indicating whether that type of sandboxing is supported.
Currently this is always the same as hasSeccompBPF, but that could change
in the future.
Some changes have been made to the "mozilla/Sandbox.h" interface to
support this; the idea is that the MOZ_DISABLE_*_SANDBOX environment
variables should be equivalent to disabling MOZ_*_SANDBOX at build time.
There are, sadly, many combinations of linkage in use throughout the tree.
The main differentiator, though, is between program/libraries related to
Gecko or not. Kind of. Some need mozglue, some don't. Some need dependent
linkage, some standalone.
Anyways, these new templates remove the need to manually define the
right dependencies against xpcomglue, nspr, mozalloc and mozglue
in most cases.
Places that build programs and were resetting MOZ_GLUE_PROGRAM_LDFLAGS
or that build libraries and were resetting MOZ_GLUE_LDFLAGS can now
just not use those Gecko-specific templates.
This is mostly for ASAN builds, which --disable-crash-reporter, but also
fixes a related papercut: debug builds don't use the crash reporter
unless overridden with an environment variable.
Note: this is Linux-only, so NS_StackWalk is always part of the build;
see also bug 1063455.
