Kernel: Convert random bytes interface to use AK::Bytes

Author: https://github.com/bgianfo
Commit: https://github.com/SerenityOS/serenity/commit/f3baa5d8c91
Pull-request: https://github.com/SerenityOS/serenity/pull/9720

Kernel/Devices/RandomDevice.cpp

@@ -32,7 +32,7 @@ bool RandomDevice::can_read(const FileDescription&, size_t) const
 KResultOr<size_t> RandomDevice::read(FileDescription&, u64, UserOrKernelBuffer& buffer, size_t size)
 {
     return buffer.write_buffered<256>(size, [&](u8* data, size_t data_size) {
-        get_good_random_bytes(data, data_size);
+        get_good_random_bytes({ data, data_size });
         return data_size;
     });
 }

Kernel/Random.cpp

@@ -87,7 +87,7 @@ void KernelRng::wake_if_ready()
 
 size_t EntropySource::next_source { static_cast<size_t>(EntropySource::Static::MaxHardcodedSourceIndex) };
 
-static void do_get_fast_random_bytes(u8* buffer, size_t buffer_size)
+static void do_get_fast_random_bytes(Bytes buffer)
 {
 
     union {
@@ -95,7 +95,7 @@ static void do_get_fast_random_bytes(u8* buffer, size_t buffer_size)
         u32 value;
     } u;
     size_t offset = 4;
-    for (size_t i = 0; i < buffer_size; ++i) {
+    for (size_t i = 0; i < buffer.size(); ++i) {
         if (offset >= 4) {
             auto current_next = s_next_random_value.load();
             for (;;) {
@@ -111,7 +111,7 @@ static void do_get_fast_random_bytes(u8* buffer, size_t buffer_size)
     }
 }
 
-bool get_good_random_bytes(u8* buffer, size_t buffer_size, bool allow_wait, bool fallback_to_fast)
+bool get_good_random_bytes(Bytes buffer, bool allow_wait, bool fallback_to_fast)
 {
     bool result = false;
     auto& kernel_rng = KernelRng::the();
@@ -127,7 +127,7 @@ bool get_good_random_bytes(u8* buffer, size_t buffer_size, bool allow_wait, bool
         for (;;) {
             {
                 MutexLocker locker(KernelRng::the().lock());
-                if (kernel_rng.resource().get_random_bytes(buffer, buffer_size)) {
+                if (kernel_rng.resource().get_random_bytes(buffer)) {
                     result = true;
                     break;
                 }
@@ -136,11 +136,11 @@ bool get_good_random_bytes(u8* buffer, size_t buffer_size, bool allow_wait, bool
         }
     } else {
         // We can't wait/block here, or we are not allowed to block/wait
-        if (kernel_rng.resource().get_random_bytes(buffer, buffer_size)) {
+        if (kernel_rng.resource().get_random_bytes(buffer)) {
             result = true;
         } else if (fallback_to_fast) {
             // If interrupts are disabled
-            do_get_fast_random_bytes(buffer, buffer_size);
+            do_get_fast_random_bytes(buffer);
             result = true;
         }
     }
@@ -152,11 +152,11 @@ bool get_good_random_bytes(u8* buffer, size_t buffer_size, bool allow_wait, bool
     return result;
 }
 
-void get_fast_random_bytes(u8* buffer, size_t buffer_size)
+void get_fast_random_bytes(Bytes buffer)
 {
     // Try to get good randomness, but don't block if we can't right now
     // and allow falling back to fast randomness
-    auto result = get_good_random_bytes(buffer, buffer_size, false, true);
+    auto result = get_good_random_bytes(buffer, false, true);
     VERIFY(result);
 }
 

Kernel/Random.h

@@ -35,7 +35,7 @@ public:
     {
     }
 
-    bool get_random_bytes(u8* buffer, size_t n)
+    bool get_random_bytes(Bytes buffer)
     {
         SpinlockLocker lock(m_lock);
         if (!is_ready())
@@ -47,13 +47,12 @@ public:
         VERIFY(is_seeded());
 
         // FIXME: More than 2^20 bytes cannot be generated without refreshing the key.
-        VERIFY(n < (1 << 20));
+        VERIFY(buffer.size() < (1 << 20));
 
         typename CipherType::CTRMode cipher(m_key, KeySize, Crypto::Cipher::Intent::Encryption);
 
-        Bytes buffer_span { buffer, n };
         auto counter_span = m_counter.bytes();
-        cipher.key_stream(buffer_span, counter_span, &counter_span);
+        cipher.key_stream(buffer, counter_span, &counter_span);
 
         // Extract a new key from the prng stream.
         Bytes key_span = m_key.bytes();
@@ -173,14 +172,15 @@ private:
 // NOTE: These API's are primarily about expressing intent/needs in the calling code.
 //       The only difference is that get_fast_random is guaranteed not to block.
 
-void get_fast_random_bytes(u8*, size_t);
+void get_fast_random_bytes(Bytes);
-bool get_good_random_bytes(u8*, size_t, bool allow_wait = true, bool fallback_to_fast = true);
+bool get_good_random_bytes(Bytes bytes, bool allow_wait = true, bool fallback_to_fast = true);
 
 template<typename T>
 inline T get_fast_random()
 {
     T value;
-    get_fast_random_bytes(reinterpret_cast<u8*>(&value), sizeof(T));
+    Bytes bytes { reinterpret_cast<u8*>(&value), sizeof(T) };
+    get_fast_random_bytes(bytes);
     return value;
 }
 
@@ -188,7 +188,8 @@ template<typename T>
 inline T get_good_random()
 {
     T value;
-    get_good_random_bytes(reinterpret_cast<u8*>(&value), sizeof(T));
+    Bytes bytes { reinterpret_cast<u8*>(&value), sizeof(T) };
+    get_good_random_bytes(bytes);
     return value;
 }
 

Kernel/Syscalls/execve.cpp

@@ -724,7 +724,7 @@ static Vector<ELF::AuxiliaryValue> generate_auxiliary_vector(FlatPtr load_base,
     auxv.append({ ELF::AuxiliaryValue::Secure, ((uid != euid) || (gid != egid)) ? 1 : 0 });
 
     char random_bytes[16] {};
-    get_fast_random_bytes((u8*)random_bytes, sizeof(random_bytes));
+    get_fast_random_bytes({ (u8*)random_bytes, sizeof(random_bytes) });
 
     auxv.append({ ELF::AuxiliaryValue::Random, String(random_bytes, sizeof(random_bytes)) });
 

Kernel/Syscalls/getrandom.cpp

@@ -24,7 +24,7 @@ KResultOr<FlatPtr> Process::sys$getrandom(Userspace<void*> buffer, size_t buffer
     if (!data_buffer.has_value())
         return EFAULT;
     auto result = data_buffer.value().write_buffered<1024>(buffer_size, [&](u8* buffer, size_t buffer_bytes) {
-        get_good_random_bytes(buffer, buffer_bytes);
+        get_good_random_bytes({ buffer, buffer_bytes });
         return buffer_bytes;
     });
     if (result.is_error())