Windows 7 support? Missing ProcessPrng
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Hello! Thanks for letting us know about this problem, and for the reference to how Rust solved it. I was trying to reproduce this with aws-lc-rs, but I'm having trouble with the build. I suspect my issue relates to not having the toolchain setup. (Since this is a tier 3 platform, are there any pre-built toolchains available?) Here's what I tried (on a Windows host using the bash shell provided by Git), and the resulting error: If you can provide some guidance on how to setup a development environment for this, it would be appreciated. Thanks! |
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Hey, I appreciate you being open to supporting a legacy system like Windows 7. For my initial test project (shown above) I also used [dependencies]
aws-lc-rs = { version = "1.11.0", default-features = false, features = ["aws-lc-sys", "prebuilt-nasm"] }If I reference [dependencies]
aws-lc-rs = { path = "../aws-lc-rs/aws-lc-rs", default-features = false, features = ["aws-lc-sys", "prebuilt-nasm"] }Do you have an idea what might cause this error? Errors building test project with direct
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This looks like the error I get when I forget to initialize the git submodules. (The Makefile in our project has some convenient targets for doing this.) Thanks for the response. I'll take a closer look at this tomorrow. |
This is part of rustls's performance CI infrastructure, and is not intended to be portable to platforms other than linux. |
Thanks, I somehow missed that. Using my test project with The previous code in this repo used The patch that I've useddiff --git a/crypto/rand_extra/windows.c b/crypto/rand_extra/windows.c
--- a/crypto/rand_extra/windows.c (revision 745359e8569fdafa8897ac2fffdfd0fdcf620563)
+++ b/crypto/rand_extra/windows.c (date 1732146659715)
@@ -24,6 +24,11 @@
OPENSSL_MSVC_PRAGMA(warning(push, 3))
#include <windows.h>
+#include <bcrypt.h>
+
+#ifndef NT_SUCCESS
+#define NT_SUCCESS(Status) ((NTSTATUS)(Status) >= 0)
+#endif
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP) && \
!WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)
@@ -56,17 +61,44 @@
#else
-// See: https://learn.microsoft.com/en-us/windows/win32/seccng/processprng
-typedef BOOL (WINAPI *ProcessPrngFunction)(PBYTE pbData, SIZE_T cbData);
-static ProcessPrngFunction g_processprng_fn = NULL;
+typedef NTSTATUS (WINAPI *BCryptGenRandomFunction)(
+_In_opt_ BCRYPT_ALG_HANDLE hAlgorithm,
+_Out_writes_bytes_(cbBuffer) PUCHAR pbBuffer,
+_In_ ULONG cbBuffer,
+_In_ ULONG dwFlags
+);
+static BCryptGenRandomFunction g_BCryptGenRandom_fn = NULL;
+static BCRYPT_ALG_HANDLE g_bcrypt_algorithm = NULL;
static void init_processprng(void) {
- HMODULE hmod = LoadLibraryW(L"bcryptprimitives");
- if (hmod == NULL) {
+ HMODULE hmod = LoadLibraryW(L"bcrypt.dll");
+ if (hmod == NULL)
+ {
abort();
}
- g_processprng_fn = (ProcessPrngFunction)(void(*)(void))GetProcAddress(hmod, "ProcessPrng");
- if (g_processprng_fn == NULL) {
+
+ g_BCryptGenRandom_fn = (BCryptGenRandomFunction)GetProcAddress(hmod, "BCryptGenRandom");
+ if (g_BCryptGenRandom_fn == NULL)
+ {
+ abort();
+ }
+
+ typedef NTSTATUS (WINAPI *BCryptOpenAlgorithmProviderFunction)(
+ _Out_ BCRYPT_ALG_HANDLE *phAlgorithm,
+ _In_z_ LPCWSTR pszAlgId,
+ _In_opt_z_ LPCWSTR pszImplementation,
+ _In_ ULONG dwFlags
+ );
+
+ BCryptOpenAlgorithmProviderFunction algoFunc = (BCryptOpenAlgorithmProviderFunction)GetProcAddress(hmod, "BCryptOpenAlgorithmProvider");
+ if (algoFunc == NULL)
+ {
+ abort();
+ }
+
+ NTSTATUS status = algoFunc(&g_bcrypt_algorithm, BCRYPT_RNG_ALGORITHM, NULL, 0);
+ if (!NT_SUCCESS(status))
+ {
abort();
}
}
@@ -78,11 +110,11 @@
void CRYPTO_sysrand(uint8_t *out, size_t requested) {
CRYPTO_init_sysrand();
- // On non-UWP configurations, use ProcessPrng instead of BCryptGenRandom
- // to avoid accessing resources that may be unavailable inside the
- // Chromium sandbox. See https://crbug.com/74242
- if (!g_processprng_fn(out, requested)) {
- abort();
+
+ NTSTATUS status = g_BCryptGenRandom_fn(g_bcrypt_algorithm, out, (ULONG)requested, 0);
+ if (!NT_SUCCESS(status))
+ {
+ abort();
}
}Maybe it's possible to clean this up a bit and put it behind a conditional |
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Thanks for the patch! Since this involves very security sensitive logic (i.e., entropy/randomness), it will take some time for us to consider it. As you indicated, in the end this change will likely be guarded by an |
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Could one decide the code-path at compile-time? That is, if on Windows 7, then specifically compile the Maybe this I don't have a Win 7 on hand. Can you check if you have a test system set up already? |
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Problem:
I actually came here from aws-lc-rust. I tried to use the following minimal example with
x86_64-win7-windows-msvcbut as soon as the library tries to accessProcessPrngthe program aborts.Erroneous line:
aws-lc/crypto/rand_extra/windows.c
Line 68 in 745359e
Solution:
Rust recently switched from
BCryptGenRandomtoProcessPrngbut allowed a path for Windows 7.rust-lang/rust#121337
Is a similar solution also possible in this project?
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