…olnay

Use BCryptGenRandom instead of RtlGenRandom on Windows.

This removes usage of RtlGenRandom on Windows, in favour of BCryptGenRandom.

BCryptGenRandom isn't available on XP, but we dropped XP support a while ago.

Used to be needed when Rust sometimes relied on RtlGenRandom instead of
BCryptGenRandom, but that changed as of
rust-lang/rust#84096

advapi32 is still used in Rust core, but only in the deprecated
`env::home_dir` API, which we don't use:

- https://github.com/rust-lang/rust/blob/22f8bde876f2fa9c5c4e95be1bce29cc271f2b51/library/std/src/sys/windows/c.rs#L681-L689
- https://github.com/rust-lang/rust/blob/22f8bde876f2fa9c5c4e95be1bce29cc271f2b51/library/std/src/sys/windows/os.rs#L292
- https://github.com/rust-lang/rust/blob/22f8bde876f2fa9c5c4e95be1bce29cc271f2b51/library/std/src/sys/windows/os.rs#L319
- https://github.com/rust-lang/rust/blob/22f8bde876f2fa9c5c4e95be1bce29cc271f2b51/library/std/src/env.rs#L566-L575

std depends on Bcrypt on Windows starting with rust 1.57.
See rust-lang/rust#84096.

Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>

std depends on Bcrypt on Windows starting with rust 1.57.
See rust-lang/rust#84096.

Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>

Due to rust-lang/rust#84096 we need to link to bcrypt on windows else we get linker errors.

cc influxdata/flux#4406

https://app.circleci.com/pipelines/github/influxdata/flux/11766/workflows/d1ef0c61-babb-4682-8c74-7087013c873e/jobs/38341

```
C:\\Users\\circleci\\AppData\\Local\\go-build\\pkgconfig\\windows_amd64\\lib/libflux-3dd4b4346280d5a830d03b58d109be24cf44fd0ab5964e0113b470e7ba1223ed.a(std-c90c2a9f63fc5684.std.04e7289e-cgu.0.rcgu.o): In function `std::sys::windows::rand::hashmap_random_keys':
/rustc/02072b482a8b5357f7fb5e5637444ae30e423c40\/library\std\src\sys\windows/rand.rs:10: undefined reference to `BCryptGenRandom'
/rustc/02072b482a8b5357f7fb5e5637444ae30e423c40\/library\std\src\sys\windows/rand.rs:10: undefined reference to `BCryptGenRandom'
collect2.exe: error: ld returned 1 exit status

Exited with code exit status 2

```

Rust 1.57 added the dependency: rust-lang/rust#84096

rust-lang/rust#84096
rust-lang/rust#91974 (comment)

Issue rust-lang#84096 changed the hashmap RNG to use BCryptGenRandom instead of
RtlGenRandom on Windows.

Mozilla Firefox started experiencing random failures in
env_logger::Builder::new() (Issue rust-lang#94098) during initialization of their
unsandboxed main process with an "Access Denied" error message from
BCryptGenRandom(), which is used by the HashMap contained in
env_logger::Builder

The root cause appears to be a virus scanner or other software interfering
with BCrypt DLLs loading.

This change adds a fallback option if BCryptGenRandom is unusable for
whatever reason. It will fallback to RtlGenRandom in this case.

Fixes rust-lang#94098

Make HashMap fall back to RtlGenRandom if BCryptGenRandom fails

With PR rust-lang#84096, Rust `std::collections::hash_map::RandomState` changed from using `RtlGenRandom()` ([msdn](https://docs.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom)) to `BCryptGenRandom()` ([msdn](https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom)) as its source of secure randomness after much discussion ([here](rust-random/getrandom#65 (comment)), among other places).

Unfortunately, after that PR landed, Mozilla Firefox started experiencing fairly-rare crashes during startup while attempting to initialize the `env_logger` crate. ([docs for env_logger](https://docs.rs/env_logger/latest/env_logger/)) The root issue is that on some machines, `BCryptGenRandom()` will fail with an `Access is denied. (os error 5)` error message. ([Bugzilla issue 1754490](https://bugzilla.mozilla.org/show_bug.cgi?id=1754490)) (Discussion in issue rust-lang#94098)

Note that this is happening upon startup of Firefox's unsandboxed Main Process, so this behavior is different and separate from previous issues ([like this](https://bugzilla.mozilla.org/show_bug.cgi?id=1746254)) where BCrypt DLLs were blocked by process sandboxing. In the case of sandboxing, we knew we were doing something abnormal and expected that we'd have to resort to abnormal measures to make it work.

However, in this case we are in a regular unsandboxed process just trying to initialize `env_logger` and getting a panic. We suspect that this may be caused by a virus scanner or some other security software blocking the loading of the BCrypt DLLs, but we're not completely sure as we haven't been able to replicate locally.

It is also possible that Firefox is not the only software affected by this; we just may be one of the pieces of Rust software that has the telemetry and crash reporting necessary to catch it.

I have read some of the historical discussion around using `BCryptGenRandom()` in Rust code, and I respect the decision that was made and agree that it was a good course of action, so I'm not trying to open a discussion about a return to `RtlGenRandom()`. Instead, I'd like to suggest that perhaps we use `RtlGenRandom()` as a "fallback RNG" in the case that BCrypt doesn't work.

This pull request implements this fallback behavior. I believe this would improve the robustness of this essential data structure within the standard library, and I see only 2 potential drawbacks:

1. Slight added overhead: It should be quite minimal though. The first call to `sys::rand::hashmap_random_keys()` will incur a bit of initialization overhead, and every call after will incur roughly 2 non-atomic global reads and 2 easily predictable branches. Both should be negligible compared to the actual cost of generating secure random numbers
2. `RtlGenRandom()` is deprecated by Microsoft: Technically true, but as mentioned in [this comment on GoLang](golang/go#33542 (comment)), this API is ubiquitous in Windows software and actually removing it would break lots of things. Also, Firefox uses it already in [our C++ code](https://searchfox.org/mozilla-central/rev/5f88c1d6977e03e22d3420d0cdf8ad0113c2eb31/mfbt/RandomNum.cpp#25), and [Chromium uses it in their code as well](https://source.chromium.org/chromium/chromium/src/+/main:base/rand_util_win.cc) (which transitively means that Microsoft uses it in their own web browser, Edge). If there did come a time when Microsoft truly removes this API, it should be easy enough for Rust to simply remove the fallback in the code I've added here

Make HashMap fall back to RtlGenRandom if BCryptGenRandom fails

With PR rust-lang#84096, Rust `std::collections::hash_map::RandomState` changed from using `RtlGenRandom()` ([msdn](https://docs.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom)) to `BCryptGenRandom()` ([msdn](https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom)) as its source of secure randomness after much discussion ([here](rust-random/getrandom#65 (comment)), among other places).

Unfortunately, after that PR landed, Mozilla Firefox started experiencing fairly-rare crashes during startup while attempting to initialize the `env_logger` crate. ([docs for env_logger](https://docs.rs/env_logger/latest/env_logger/)) The root issue is that on some machines, `BCryptGenRandom()` will fail with an `Access is denied. (os error 5)` error message. ([Bugzilla issue 1754490](https://bugzilla.mozilla.org/show_bug.cgi?id=1754490)) (Discussion in issue rust-lang#94098)

Note that this is happening upon startup of Firefox's unsandboxed Main Process, so this behavior is different and separate from previous issues ([like this](https://bugzilla.mozilla.org/show_bug.cgi?id=1746254)) where BCrypt DLLs were blocked by process sandboxing. In the case of sandboxing, we knew we were doing something abnormal and expected that we'd have to resort to abnormal measures to make it work.

However, in this case we are in a regular unsandboxed process just trying to initialize `env_logger` and getting a panic. We suspect that this may be caused by a virus scanner or some other security software blocking the loading of the BCrypt DLLs, but we're not completely sure as we haven't been able to replicate locally.

It is also possible that Firefox is not the only software affected by this; we just may be one of the pieces of Rust software that has the telemetry and crash reporting necessary to catch it.

I have read some of the historical discussion around using `BCryptGenRandom()` in Rust code, and I respect the decision that was made and agree that it was a good course of action, so I'm not trying to open a discussion about a return to `RtlGenRandom()`. Instead, I'd like to suggest that perhaps we use `RtlGenRandom()` as a "fallback RNG" in the case that BCrypt doesn't work.

This pull request implements this fallback behavior. I believe this would improve the robustness of this essential data structure within the standard library, and I see only 2 potential drawbacks:

1. Slight added overhead: It should be quite minimal though. The first call to `sys::rand::hashmap_random_keys()` will incur a bit of initialization overhead, and every call after will incur roughly 2 non-atomic global reads and 2 easily predictable branches. Both should be negligible compared to the actual cost of generating secure random numbers
2. `RtlGenRandom()` is deprecated by Microsoft: Technically true, but as mentioned in [this comment on GoLang](golang/go#33542 (comment)), this API is ubiquitous in Windows software and actually removing it would break lots of things. Also, Firefox uses it already in [our C++ code](https://searchfox.org/mozilla-central/rev/5f88c1d6977e03e22d3420d0cdf8ad0113c2eb31/mfbt/RandomNum.cpp#25), and [Chromium uses it in their code as well](https://source.chromium.org/chromium/chromium/src/+/main:base/rand_util_win.cc) (which transitively means that Microsoft uses it in their own web browser, Edge). If there did come a time when Microsoft truly removes this API, it should be easy enough for Rust to simply remove the fallback in the code I've added here