Kernel/LibC: Add randomfill() syscall.

This syscall aims to fill the given buffer with cryptographically secure
random data. If the syscall returns and does not cause a page fault it
will **always** have filled the buffer with random data and never gives
back any error value.

4 files changed, 12 insertions, 2 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 0542b49..99ab586 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -1,7 +1,7 @@
 CC="i686-sb-gcc"
 AS="i686-sb-as"
-OBJ = arch/i386/boot.o init/kernel.o cpu/gdt.o cpu/reload_gdt.o cpu/idt.o cpu/io.o libc/stdio/print.o drivers/keyboard.o log.o drivers/pit.o libc/string/memcpy.o libc/string/strlen.o libc/string/memcmp.o drivers/ata.o libc/string/memset.o cpu/syscall.o  read_eip.o libc/exit/assert.o process.o cpu/int_syscall.o libc/string/strcpy.o arch/i386/mmu.o kmalloc.o fs/ext2.o fs/vfs.o fs/devfs.o cpu/spinlock.o random.o libc/string/strcmp.o crypto/ChaCha20/chacha20.o crypto/SHA1/sha1.o fs/tmpfs.o libc/string/isequal.o drivers/pst.o halts.o syscalls/ppoll.o syscalls/ftruncate.o kubsan.o syscalls/mmap.o drivers/serial.o syscalls/accept.o syscalls/bind.o syscalls/socket.o socket.o poll.o fs/fifo.o hashmap/hashmap.o fs/shm.o syscalls/shm.o elf.o ksbrk.o sched/scheduler.o syscalls/stat.o libc/string/copy.o libc/string/strncpy.o drivers/mouse.o libc/string/strlcpy.o libc/string/strcat.o drivers/vbe.o syscalls/msleep.o syscalls/uptime.o syscalls/mkdir.o drivers/pci.o drivers/rtl8139.o network/ethernet.o network/arp.o network/bytes.o network/ipv4.o network/udp.o syscalls/recvfrom.o math.o syscalls/sendto.o signal.o syscalls/kill.o syscalls/sigaction.o network/tcp.o drivers/ahci.o crypto/xoshiro256plusplus/xoshiro256plusplus.o syscalls/chdir.o syscalls/getcwd.o syscalls/isatty.o
-CFLAGS = -O0 -fsanitize=vla-bound,shift-exponent,pointer-overflow,shift,signed-integer-overflow,bounds -ggdb -ffreestanding -Wall -Werror -mgeneral-regs-only -Wimplicit-fallthrough -I./libc/include/ -I. -Wno-pointer-sign -DKERNEL
+OBJ = arch/i386/boot.o init/kernel.o cpu/gdt.o cpu/reload_gdt.o cpu/idt.o cpu/io.o libc/stdio/print.o drivers/keyboard.o log.o drivers/pit.o libc/string/memcpy.o libc/string/strlen.o libc/string/memcmp.o drivers/ata.o libc/string/memset.o cpu/syscall.o  read_eip.o libc/exit/assert.o process.o cpu/int_syscall.o libc/string/strcpy.o arch/i386/mmu.o kmalloc.o fs/ext2.o fs/vfs.o fs/devfs.o cpu/spinlock.o random.o libc/string/strcmp.o crypto/ChaCha20/chacha20.o crypto/SHA1/sha1.o fs/tmpfs.o libc/string/isequal.o drivers/pst.o halts.o syscalls/ppoll.o syscalls/ftruncate.o kubsan.o syscalls/mmap.o drivers/serial.o syscalls/accept.o syscalls/bind.o syscalls/socket.o socket.o poll.o fs/fifo.o hashmap/hashmap.o fs/shm.o syscalls/shm.o elf.o ksbrk.o sched/scheduler.o syscalls/stat.o libc/string/copy.o libc/string/strncpy.o drivers/mouse.o libc/string/strlcpy.o libc/string/strcat.o drivers/vbe.o syscalls/msleep.o syscalls/uptime.o syscalls/mkdir.o drivers/pci.o drivers/rtl8139.o network/ethernet.o network/arp.o network/bytes.o network/ipv4.o network/udp.o syscalls/recvfrom.o math.o syscalls/sendto.o signal.o syscalls/kill.o syscalls/sigaction.o network/tcp.o drivers/ahci.o crypto/xoshiro256plusplus/xoshiro256plusplus.o syscalls/chdir.o syscalls/getcwd.o syscalls/isatty.o syscalls/randomfill.o
+CFLAGS = -O3 -fsanitize=vla-bound,shift-exponent,pointer-overflow,shift,signed-integer-overflow,bounds -ggdb -ffreestanding -Wall -Werror -mgeneral-regs-only -Wimplicit-fallthrough -I./libc/include/ -I. -Wno-pointer-sign -DKERNEL
 INCLUDE=-I./includes/ -I../include/ -I./libc/include/
 
 all: myos.iso
diff --git a/kernel/cpu/syscall.c b/kernel/cpu/syscall.c
index 7001d63..2a67235 100644
--- a/kernel/cpu/syscall.c
+++ b/kernel/cpu/syscall.c
@@ -155,6 +155,7 @@ void (*syscall_functions[])() = {
     (void(*))syscall_sendto,    (void(*))syscall_kill,
     (void(*))syscall_sigaction, (void(*))syscall_chdir,
     (void(*))syscall_getcwd,    (void(*))syscall_isatty,
+    (void(*))syscall_randomfill,
 };
 
 void syscall_function_handler(u32 eax, u32 arg1, u32 arg2, u32 arg3, u32 arg4,
diff --git a/kernel/includes/syscalls.h b/kernel/includes/syscalls.h
index 6642fea..ee7efec 100644
--- a/kernel/includes/syscalls.h
+++ b/kernel/includes/syscalls.h
@@ -16,6 +16,8 @@ typedef struct SYS_ACCEPT_PARAMS {
 
 int syscall_accept(SYS_ACCEPT_PARAMS *args);
 
+void syscall_randomfill(void *buffer, u32 size);
+
 typedef struct SYS_BIND_PARAMS {
   int sockfd;
   const struct sockaddr *addr;
diff --git a/kernel/syscalls/randomfill.c b/kernel/syscalls/randomfill.c
new file mode 100644
index 0000000..41f3ef0
--- /dev/null
+++ b/kernel/syscalls/randomfill.c
@@ -0,0 +1,7 @@
+#include <random.h>
+#include <typedefs.h>
+
+// This syscall will never fail. At worst a page fault will occur but if
+// the syscall returns the buffer will have been filled with random
+// data.
+void syscall_randomfill(void *buffer, u32 size) { get_random(buffer, size); }