Merge #17270: Feed environment data into RNG initializers

d1c02775aa74a0610809ac54bb241ddad61d2d8c Report amount of data gathered from environment (Pieter Wuille)
64e1e022cedf6776c5dffd488ca2e766adca5dc3 Use thread-safe atomic in perfmon seeder (Pieter Wuille)
d61f2bb076d8f17840a8e79f1583d7f6e3e6d09a Run background seeding periodically instead of unpredictably (Pieter Wuille)
483b94292e89587e5ab40a30b8a90e2f56e847f3 Add information gathered through getauxval() (Pieter Wuille)
11793ea22e1298fa7d3b44a5b6d20830248d8cf4 Feed CPUID data into RNG (Pieter Wuille)
a81c494b4c9a8c2f1a319a03375826f12863706f Use sysctl for seeding on MacOS/BSD (Pieter Wuille)
2554c1b81bb8c40e1989025c6f18e7935720b156 Gather additional entropy from the environment (Pieter Wuille)
c2a262a78c3bcc4d5e13612ab0214874abe15de0 Seed randomness with process id / thread id / various clocks (Pieter Wuille)
723c79666770b30cce9f962bed5ece8cc7d74580 [MOVEONLY] Move cpuid code from random & sha256 to compat/cpuid (Pieter Wuille)
cea3902015185adc88adbd031d919f91bc844fd7 [MOVEONLY] Move perfmon data gathering to new randomenv module (Pieter Wuille)
b51bae1a5a4fa8ef7825dd1bb09e3f47f96d7a5a doc: minor corrections in random.cpp (fanquake)

Pull request description:

  This introduces a new `randomenv` module that queries varies non-cryptographic (and non-RNG) sources of entropy available on the system; things like user IDs, system configuration, time, statistics, CPUID data.

  The idea is that these provide a fallback in scenarios where system entropy is somehow broken (note that if system entropy *fails* we will abort regardless; this is only meant to function as a last resort against undetected failure). It includes some data sources OpenSSL currently uses, and more.

  The separation between random and randomenv is a bit arbitrary, but I felt that all this "non-essential" functionality deserved to be separated from the core random module.

ACKs for top commit:
  TheBlueMatt:
    utACK d1c02775aa74a0610809ac54bb241ddad61d2d8c. Certainly no longer measuring the time elapsed between a 1ms sleep (which got removed in the latest change) is a fair tradeoff for adding about 2 million other actually-higher-entropy bits :).
  laanwj:
    ACK d1c02775aa74a0610809ac54bb241ddad61d2d8c

Tree-SHA512: d290a8db6538a164348118ee02079e4f4c8551749ea78fa44b2aad57f5df2ccbc2a12dc7d80d8f3e916d68cdd8e204faf9e1bcbec15f9054eba6b22f17c66ae3

1 files changed, 13 insertions, 1 deletions

diff --git a/configure.ac b/configure.ac
index 998c82916a..0f31bbaee5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -790,7 +790,7 @@ if test x$TARGET_OS = xdarwin; then
   AX_CHECK_LINK_FLAG([[-Wl,-dead_strip]], [LDFLAGS="$LDFLAGS -Wl,-dead_strip"])
 fi
 
-AC_CHECK_HEADERS([endian.h sys/endian.h byteswap.h stdio.h stdlib.h unistd.h strings.h sys/types.h sys/stat.h sys/select.h sys/prctl.h])
+AC_CHECK_HEADERS([endian.h sys/endian.h byteswap.h stdio.h stdlib.h unistd.h strings.h sys/types.h sys/stat.h sys/select.h sys/prctl.h sys/sysctl.h vm/vm_param.h sys/vmmeter.h sys/resources.h])
 
 # FD_ZERO may be dependent on a declaration of memcpy, e.g. in SmartOS
 # check that it fails to build without memcpy, then that it builds with
@@ -950,6 +950,18 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <unistd.h>
  [ AC_MSG_RESULT(no)]
 )
 
+AC_MSG_CHECKING(for sysctl)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/types.h>
+  #include <sys/sysctl.h>]],
+ [[ static const int name[2] = {CTL_KERN, KERN_VERSION};
+    #ifdef __linux__
+    #error "Don't use sysctl on Linux, it's deprecated even when it works"
+    #endif
+    sysctl(name, 2, nullptr, nullptr, nullptr, 0); ]])],
+ [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_SYSCTL, 1,[Define this symbol if the BSD sysctl() is available]) ],
+ [ AC_MSG_RESULT(no)]
+)
+
 AC_MSG_CHECKING(for sysctl KERN_ARND)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/types.h>
   #include <sys/sysctl.h>]],