From 7a64bdbbcf14023370b90b22de73c2f61a6f84ac Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Sun, 4 Apr 2021 00:11:00 +0200
Subject: Implemented basic user program ASLR

---
 libs/libc/Makefile     | 10 ++++++----
 libs/libc/inc/random.h |  4 ++--
 libs/libc/random.c     | 48 +++++++++++++++++++-----------------------------
 libs/libgui/Makefile   |  2 +-
 libs/libnet/Makefile   |  2 +-
 libs/libtxt/Makefile   |  2 +-
 6 files changed, 30 insertions(+), 38 deletions(-)

(limited to 'libs')

diff --git a/libs/libc/Makefile b/libs/libc/Makefile
index 24970d8..cc1b836 100644
--- a/libs/libc/Makefile
+++ b/libs/libc/Makefile
@@ -1,7 +1,8 @@
 # MIT License, Copyright (c) 2020 Marvin Borner
 
 # TODO: Remove cpu from libc?
-COBJS = sanitize.o \
+COBJS = crt/crt0.o \
+	sanitize.o \
 	errno.o \
 	str.o \
 	alloc.o \
@@ -26,11 +27,12 @@ ASFLAGS = -f elf32
 %.o: %.c
 	@$(CC) -c $(CFLAGS) $< -o $@
 
-libc: CFLAGS += -DUSER
+libc: CFLAGS += -pie -fPIE -fPIC -DUSER
 libc: $(COBJS)
-	@$(AS) $(ASFLAGS) crt/crt0.asm -o crt0.o
 	@mkdir -p ../../build/
-	@$(AR) rcs ../../build/libc.a crt0.o $+
+	@$(AS) $(ASFLAGS) crt/crti.asm -o ../../build/crti.o
+	@$(AS) $(ASFLAGS) crt/crtn.asm -o ../../build/crtn.o
+	@$(AR) rcs ../../build/libc.a ../../build/crti.o ../../build/crti.o $+
 
 libk: CFLAGS += -DKERNEL -ffreestanding -I../../kernel/inc/ $(CFLAGS_EXTRA)
 libk: $(COBJS)
diff --git a/libs/libc/inc/random.h b/libs/libc/inc/random.h
index a82524c..6360625 100644
--- a/libs/libc/inc/random.h
+++ b/libs/libc/inc/random.h
@@ -5,9 +5,9 @@
 
 #include <def.h>
 
+#define rand_range(min, max) (rand() % ((max) + 1 - (min)) + (min))
+
 void srand(u32 seed);
-u32 rdrand(void);
-u32 rdseed(void);
 u32 rand(void);
 char *randstr(u32 size);
 
diff --git a/libs/libc/random.c b/libs/libc/random.c
index 6296407..983357f 100644
--- a/libs/libc/random.c
+++ b/libs/libc/random.c
@@ -15,46 +15,36 @@ void srand(u32 seed)
 	g_seed = seed;
 }
 
-u32 rdrand(void)
+static u32 default_rand(void)
 {
-#ifdef KERNEL
-	if (!(cpu_features.ecx & CPUID_FEAT_ECX_RDRND))
-		return rand();
-
-	u32 rd;
-	__asm__ volatile("1:\n"
-			 "rdrand %0\n"
-			 "jnc 1b\n"
-			 : "=r"(rd));
-	return rd;
-#else
-	return rand();
-#endif
+	g_seed = g_seed * 1103515245 + 12345;
+	return (g_seed >> 16) & 0x7FFF;
 }
 
-u32 rdseed(void)
+u32 rand(void)
 {
 #ifdef KERNEL
-	if (!(cpu_extended_features.ebx & CPUID_EXT_FEAT_EBX_RDSEED))
-		return rand();
-
 	u32 rd;
-	__asm__ volatile("1:\n"
-			 "rdseed %0\n"
-			 "jnc 1b\n"
-			 : "=r"(rd));
+	if (cpu_extended_features.ebx & CPUID_EXT_FEAT_EBX_RDSEED) {
+		__asm__ volatile("1:\n"
+				 "rdseed %0\n"
+				 "jnc 1b\n"
+				 : "=r"(rd));
+	} else if (cpu_features.ecx & CPUID_FEAT_ECX_RDRND) {
+		__asm__ volatile("1:\n"
+				 "rdrand %0\n"
+				 "jnc 1b\n"
+				 : "=r"(rd));
+	} else {
+		rd = default_rand();
+	}
+
 	return rd;
 #else
-	return rand();
+	return default_rand();
 #endif
 }
 
-u32 rand(void)
-{
-	g_seed = g_seed * 1103515245 + 12345;
-	return (g_seed >> 16) & 0x7FFF;
-}
-
 char *randstr(u32 size)
 {
 	if (!size)
diff --git a/libs/libgui/Makefile b/libs/libgui/Makefile
index e04b703..47e2556 100644
--- a/libs/libgui/Makefile
+++ b/libs/libgui/Makefile
@@ -10,7 +10,7 @@ CC = ccache ../../cross/opt/bin/i686-elf-gcc
 LD = ccache ../../cross/opt/bin/i686-elf-ld
 AR = ccache ../../cross/opt/bin/i686-elf-ar
 
-CFLAGS = $(CFLAGS_DEFAULT) -I../ -I../libc/inc/ -DUSER
+CFLAGS = $(CFLAGS_DEFAULT) -I../ -I../libc/inc/ -pie -fPIE -fPIC -DUSER
 
 all: libgui
 
diff --git a/libs/libnet/Makefile b/libs/libnet/Makefile
index 69c899d..7094875 100644
--- a/libs/libnet/Makefile
+++ b/libs/libnet/Makefile
@@ -5,7 +5,7 @@ CC = ccache ../../cross/opt/bin/i686-elf-gcc
 LD = ccache ../../cross/opt/bin/i686-elf-ld
 AR = ccache ../../cross/opt/bin/i686-elf-ar
 
-CFLAGS = $(CFLAGS_DEFAULT) -I../ -I../libc/inc/ -DUSER
+CFLAGS = $(CFLAGS_DEFAULT) -I../ -I../libc/inc/ -pie -fPIE -fPIC -DUSER
 
 all: libtxt
 
diff --git a/libs/libtxt/Makefile b/libs/libtxt/Makefile
index 6d06502..38fe01f 100644
--- a/libs/libtxt/Makefile
+++ b/libs/libtxt/Makefile
@@ -5,7 +5,7 @@ CC = ccache ../../cross/opt/bin/i686-elf-gcc
 LD = ccache ../../cross/opt/bin/i686-elf-ld
 AR = ccache ../../cross/opt/bin/i686-elf-ar
 
-CFLAGS = $(CFLAGS_DEFAULT) -I../ -I../libc/inc/ -DUSER
+CFLAGS = $(CFLAGS_DEFAULT) -I../ -I../libc/inc/ -pie -fPIE -fPIC -DUSER
 
 all: libtxt
 
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