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authorEelco Dolstra <eelco.dolstra@logicblox.com>2016-02-22T13·49+0100
committerEelco Dolstra <eelco.dolstra@logicblox.com>2016-02-22T14·51+0100
commit840056af04561e7fed31c459948be7c0e038864a (patch)
tree6175fd163cc973c50a50046b000837a3016ccc0b /src/libmain
parentd361901bfe50f43ed1b94e89c95718b072f07821 (diff)
Make OpenSSL usage thread-safe
OpenSSL can randomly segfault unless we register a callback function
to do locking.

https://www.openssl.org/docs/manmaster/crypto/threads.html
Diffstat (limited to 'src/libmain')
-rw-r--r--src/libmain/local.mk2
-rw-r--r--src/libmain/shared.cc24
-rw-r--r--src/libmain/shared.hh4
3 files changed, 26 insertions, 4 deletions
diff --git a/src/libmain/local.mk b/src/libmain/local.mk
index 16dbf752823d..4ff114e4b332 100644
--- a/src/libmain/local.mk
+++ b/src/libmain/local.mk
@@ -6,6 +6,8 @@ libmain_DIR := $(d)
 
 libmain_SOURCES := $(wildcard $(d)/*.cc)
 
+libutil_LDFLAGS = $(OPENSSL_LIBS)
+
 libmain_LIBS = libstore libutil libformat
 
 libmain_ALLOW_UNDEFINED = 1
diff --git a/src/libmain/shared.cc b/src/libmain/shared.cc
index 88ed52497fb9..8f2aa842036a 100644
--- a/src/libmain/shared.cc
+++ b/src/libmain/shared.cc
@@ -5,10 +5,11 @@
 #include "store-api.hh"
 #include "util.hh"
 
-#include <iostream>
+#include <algorithm>
 #include <cctype>
 #include <exception>
-#include <algorithm>
+#include <iostream>
+#include <mutex>
 
 #include <cstdlib>
 #include <sys/time.h>
@@ -16,7 +17,7 @@
 #include <unistd.h>
 #include <signal.h>
 
-extern char * * environ;
+#include <openssl/crypto.h>
 
 
 namespace nix {
@@ -103,7 +104,18 @@ string getArg(const string & opt,
 }
 
 
-void detectStackOverflow();
+/* OpenSSL is not thread-safe by default - it will randomly crash
+   unless the user supplies a mutex locking function. So let's do
+   that. */
+static std::vector<std::mutex> opensslLocks;
+
+static void opensslLockCallback(int mode, int type, const char * file, int line)
+{
+    if (mode & CRYPTO_LOCK)
+        opensslLocks[type].lock();
+    else
+        opensslLocks[type].unlock();
+}
 
 
 void initNix()
@@ -119,6 +131,10 @@ void initNix()
     if (getEnv("IN_SYSTEMD") == "1")
         logType = ltSystemd;
 
+    /* Initialise OpenSSL locking. */
+    opensslLocks = std::vector<std::mutex>(CRYPTO_num_locks());
+    CRYPTO_set_locking_callback(opensslLockCallback);
+
     settings.processEnvironment();
     settings.loadConfFile();
 
diff --git a/src/libmain/shared.hh b/src/libmain/shared.hh
index 3f3f6f7232e0..0682267fa376 100644
--- a/src/libmain/shared.hh
+++ b/src/libmain/shared.hh
@@ -101,4 +101,8 @@ struct PrintFreed
 };
 
 
+/* Install a SIGSEGV handler to detect stack overflows. */
+void detectStackOverflow();
+
+
 }