1. In many cases, sandboxes need to allow /proc/stat and /proc/cpuinfo so that
get_nprocs(3) will work; otherwise, per-CPU logic can't determine how many CPUs
there are. Unfortunately, some of those sandboxes also disable namespaces. The
solution is to provide two functions: AllowRestartableSequencesWithProcFiles(),
which allows syscalls and files; and AllowRestartableSequences(), which allows
syscalls only. Sandboxes should usually call the former; sandboxes that disable
namespaces should instead call the latter and are responsible for allowing the
files via the deprecated Fs mechanism.
2. Make the mmap(2) policy evaluate prot AND flags, not prot OR flags.
3. Order the code and the comments identically for better readability.
PiperOrigin-RevId: 386414028
Change-Id: I016b1854ed1da9c9bcff7b351c5e0041093b8193
The default policy causes immediate termination of a sandboxee that
calls `bpf`(2).
This does not allow for try-call use of `bpf()` to test for optional
features.
To support such try-call use cases, sandboxes would like to say:
```
sandbox2::PolicyBuilder builder;
builder.BlockSyscallWithErrno(__NR_bpf, EPERM);
```
but this doesn't work because the default policy unconditionally treats
`bpf()` as a sandbox violation.
Remove the bpf violation check from the policy if `bpf()` is explicitly
blocked with an errno.
PiperOrigin-RevId: 345239389
Change-Id: I7fcfd3a938c610c8679edf8e1fa0238b32cc9db4
This allows us to remove some uses of macros.
Related changes:
- Make it clear that we support hosting sandboxed binaries from 64-bit
processes only. CPU architectures are x86-64 and POWER64 (little endian).
- Introduced CPU architecture macros, abstracting away compiler specifics
PiperOrigin-RevId: 330918134
Change-Id: Ife7ad5f14723eec9f68055127b0583b8aecd38dd
BoringSSL (which is the crypto library used by most Google products) is starting to use madvise(_, _, MADV_WIPEONFORK) to protect random-number state from being duplicated by fork(). This causes extra madvise calls that sandboxes need to permit in order to continue functioning.
PiperOrigin-RevId: 309173849
Change-Id: I007dacc1ff1fd0ccc138caaa08735cfe5bc78234
This makes the class more ergonomic because
* You don't have to heap allocate the builder.
* You can create a policy builder "template" and re-use it across sandboxes to avoid repetitive work.
PiperOrigin-RevId: 273555679
Change-Id: I4084ee9c74f95ebfde873eb0dc021b3b3cdc5ea2
Currently mostly no-op, but this is the first step to turn namespaces on
by default.
PiperOrigin-RevId: 249439158
Change-Id: I5eeb1216dc868c660f62ad50c34f626afbf7db61
