metrics have been added

3 files changed, 155 insertions, 0 deletions

diff --git a/library/cpp/string_utils/secret_string/secret_string.cpp b/library/cpp/string_utils/secret_string/secret_string.cpp
new file mode 100644
index 00000000000..3b68d3cd274
--- /dev/null
+++ b/library/cpp/string_utils/secret_string/secret_string.cpp
@@ -0,0 +1,68 @@
+#include "secret_string.h"
+
+#include <util/system/madvise.h>
+
+namespace NSecretString {
+    TSecretString::TSecretString(TStringBuf value) {
+        Init(value);
+    }
+
+    TSecretString::~TSecretString() {
+        try {
+            Clear();
+        } catch (...) {
+        }
+    }
+
+    TSecretString& TSecretString::operator=(const TSecretString& o) {
+        if (&o == this) {
+            return *this;
+        }
+
+        Init(o.Value_);
+
+        return *this;
+    }
+
+    /**
+     * It is not honest "move". Actually it is copy-assignment with cleaning of other instance.
+     * This way allowes to avoid side effects of string optimizations:
+     *   Copy-On-Write or Short-String-Optimization
+     */
+    TSecretString& TSecretString::operator=(TSecretString&& o) {
+        if (&o == this) {
+            return *this;
+        }
+
+        Init(o.Value_);
+        o.Clear();
+
+        return *this;
+    }
+
+    TSecretString& TSecretString::operator=(const TStringBuf o) {
+        Init(o);
+
+        return *this;
+    }
+
+    void TSecretString::Init(TStringBuf value) {
+        Clear();
+        if (value.empty()) {
+            return;
+        }
+
+        Value_ = value;
+        MadviseExcludeFromCoreDump(Value_);
+    }
+
+    void TSecretString::Clear() {
+        if (Value_.empty()) {
+            return;
+        }
+
+        SecureZero((void*)Value_.data(), Value_.size());
+        MadviseIncludeIntoCoreDump(Value_);
+        Value_.clear();
+    }
+}
diff --git a/library/cpp/string_utils/secret_string/secret_string.h b/library/cpp/string_utils/secret_string/secret_string.h
new file mode 100644
index 00000000000..fdb9f6a85ce
--- /dev/null
+++ b/library/cpp/string_utils/secret_string/secret_string.h
@@ -0,0 +1,74 @@
+#pragma once
+
+#include <library/cpp/string_utils/ztstrbuf/ztstrbuf.h>
+
+#include <util/generic/string.h>
+
+namespace NSecretString {
+    /**
+     * TSecretString allowes to store some long lived secrets in "secure" storage in memory.
+     * Common usage:
+     *  1) read secret value from disk/env/etc
+     *  2) put it into TSecretString
+     *  3) destory secret copy from 1)
+     *
+     * Useful scenerios for TSecretString:
+     *   - in memory only tasks: using key to create crypto signature;
+     *   - rare network cases: db password on connection or OAuth token in background tasks.
+     *     These cases disclosure the secret
+     *       because of sending it over network with some I/O frameworks.
+     *     Usually such frameworks copy input params to provide network protocol: gRPC, for example.
+     *
+     * Supported features:
+     *  1. Exclude secret from core dump.
+     *     madvise(MADV_DONTDUMP) in ctor excludes full memory page from core dump.
+     *     madvise(MADV_DODUMP) in dtor reverts previous action.
+     *  2. Zero memory before free.
+     *
+     * Code dump looks like this:
+(gdb) print s
+$1 = (const TSecretString &) @0x7fff23c4c560: {
+  Value_ = {<TStringBase<TBasicString<char, std::__y1::char_traits<char> >, char, std::__y1::char_traits<char> >> = {
+      static npos = <optimized out>}, Data_ = 0x107c001d8 <error: Cannot access memory at address 0x107c001d8>}}
+     */
+
+    class TSecretString {
+    public:
+        TSecretString() = default;
+        TSecretString(TStringBuf value);
+        ~TSecretString();
+
+        TSecretString(const TSecretString& o)
+            : TSecretString(o.Value())
+        {
+        }
+
+        TSecretString(TSecretString&& o)
+            : TSecretString(o.Value())
+        {
+            o.Clear();
+        }
+
+        TSecretString& operator=(const TSecretString& o);
+        TSecretString& operator=(TSecretString&& o);
+
+        TSecretString& operator=(const TStringBuf o);
+
+        operator TZtStringBuf() const {
+            return Value();
+        }
+
+        // Provides zero terminated string
+        TZtStringBuf Value() const {
+            return TZtStringBuf(Value_);
+        }
+
+    private:
+        // TStringBuf breaks Copy-On-Write to provide correct copy-ctor and copy-assignment
+        void Init(TStringBuf value);
+        void Clear();
+
+    private:
+        TString Value_;
+    };
+}
diff --git a/library/cpp/string_utils/secret_string/ya.make b/library/cpp/string_utils/secret_string/ya.make
new file mode 100644
index 00000000000..c1d43f7a1d5
--- /dev/null
+++ b/library/cpp/string_utils/secret_string/ya.make
@@ -0,0 +1,13 @@
+LIBRARY()
+
+SRCS(
+    secret_string.cpp
+)
+
+PEERDIR(
+    library/cpp/string_utils/ztstrbuf
+)
+
+END()
+
+RECURSE_FOR_TESTS(ut)