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.

9 files changed, 44 insertions, 3 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); }
diff --git a/userland/libc/Makefile b/userland/libc/Makefile
index 146492b..a47d7bf 100644
--- a/userland/libc/Makefile
+++ b/userland/libc/Makefile
@@ -2,7 +2,7 @@ CC="i686-sb-gcc"
 AR="i686-sb-ar"
 AS="i686-sb-as"
 CFLAGS = -ggdb -ffreestanding -O2 -Wall -Wextra -pedantic -Wimplicit-fallthrough -I./include/ -static -I../../include/ -Wno-int-conversion -Wno-unused-parameter -Wno-return-type
-OBJ=crt0.o libc.o malloc/malloc.o pty.o sys/mman/mmap.o memset.o assert.o stdio/snprintf.o stdio/vfprintf.o string/memcpy.o string/memcmp.o string/strcmp.o ubsan.o string/strcpy.o isspace.o stdio/puts.o stdio/putchar.o dirent/opendir.o dirent/readdir.o dirent/closedir.o unistd/getopt.o dirent/scandir.o dirent/alphasort.o stdio/printf.o stdio/vdprintf.o stdio/vprintf.o stdio/dprintf.o stdio/vprintf.o string/strlen.o string/strnlen.o stdio/stdin.o stdio/getchar.o stdio/fgetc.o arpa/inet/htons.o arpa/inet/htonl.o stdio/fread.o stdio/fwrite.o stdio/fopen.o stdio/fclose.o stdio/fseek.o ctype/isascii.o stdio/fprintf.o stdlib/atoi.o stdlib/strtol.o ctype/toupper.o ctype/tolower.o string/strcat.o string/strchr.o string/sscanf.o sys/stat/stat.o stdlib/getenv.o string/strrchr.o stdio/ftell.o stdio/tmpfile.o stdio/fgets.o stdio/feof.o stdio/fscanf.o stdio/ungetc.o string/strncmp.o stdio/fputc.o string/strncpy.o stdio/remove.o stdio/ferror.o stdio/fputs.o stdlib/rand.o stdlib/srand.o unistd/getpid.o stdlib/strtoul.o stdio/fflush.o stdlib/abort.o string/strcspn.o time/localtime.o time/time.o time/clock_gettime.o time/gmtime.o time/strftime.o string/strpbrk.o ctype/isdigit.o ctype/isalpha.o ctype/isxdigit.o ctype/ispunct.o stdio/setvbuf.o stdio/fileno.o stdio/putc.o stdio/sprintf.o stdlib/abs.o string/strspn.o stdlib/qsort.o string/memmove.o setjmp/longjmp.o setjmp/setjmp.o libgen/basename.o string/strdup.o string/strndup.o string/strlcpy.o stdlib/atexit.o stdio/open_memstream.o libgen/dirname.o unistd/unlink.o string/strstr.o string/strcasecmp.o string/strncasecmp.o stdlib/mkstemp.o string/strtok.o unistd/execvp.o unistd/_exit.o ctype/isalnum.o time/ctime_r.o stdlib/strtold.o sys/time/gettimeofday.o stdio/fgetpos.o stdio/fsetpos.o ctype/isprint.o stdlib/system.o stdio/tmpnam.o unistd/msleep.o stdlib/atof.o stdlib/strtod.o stdio/rename.o sys/stat/mkdir.o unistd/uptime.o unistd/ftruncate.o sys/socket/recvfrom.o sys/socket/sendto.o signal/kill.o signal/sigaction.o unistd/chdir.o unistd/getcwd.o stdio/getdelim.o stdio/getline.o unistd/isatty.o sys/socket/listen.o stdlib/realpath.o math/min.o math/max.o systemcall.o
+OBJ=crt0.o libc.o malloc/malloc.o pty.o sys/mman/mmap.o memset.o assert.o stdio/snprintf.o stdio/vfprintf.o string/memcpy.o string/memcmp.o string/strcmp.o ubsan.o string/strcpy.o isspace.o stdio/puts.o stdio/putchar.o dirent/opendir.o dirent/readdir.o dirent/closedir.o unistd/getopt.o dirent/scandir.o dirent/alphasort.o stdio/printf.o stdio/vdprintf.o stdio/vprintf.o stdio/dprintf.o stdio/vprintf.o string/strlen.o string/strnlen.o stdio/stdin.o stdio/getchar.o stdio/fgetc.o arpa/inet/htons.o arpa/inet/htonl.o stdio/fread.o stdio/fwrite.o stdio/fopen.o stdio/fclose.o stdio/fseek.o ctype/isascii.o stdio/fprintf.o stdlib/atoi.o stdlib/strtol.o ctype/toupper.o ctype/tolower.o string/strcat.o string/strchr.o string/sscanf.o sys/stat/stat.o stdlib/getenv.o string/strrchr.o stdio/ftell.o stdio/tmpfile.o stdio/fgets.o stdio/feof.o stdio/fscanf.o stdio/ungetc.o string/strncmp.o stdio/fputc.o string/strncpy.o stdio/remove.o stdio/ferror.o stdio/fputs.o stdlib/rand.o stdlib/srand.o unistd/getpid.o stdlib/strtoul.o stdio/fflush.o stdlib/abort.o string/strcspn.o time/localtime.o time/time.o time/clock_gettime.o time/gmtime.o time/strftime.o string/strpbrk.o ctype/isdigit.o ctype/isalpha.o ctype/isxdigit.o ctype/ispunct.o stdio/setvbuf.o stdio/fileno.o stdio/putc.o stdio/sprintf.o stdlib/abs.o string/strspn.o stdlib/qsort.o string/memmove.o setjmp/longjmp.o setjmp/setjmp.o libgen/basename.o string/strdup.o string/strndup.o string/strlcpy.o stdlib/atexit.o stdio/open_memstream.o libgen/dirname.o unistd/unlink.o string/strstr.o string/strcasecmp.o string/strncasecmp.o stdlib/mkstemp.o string/strtok.o unistd/execvp.o unistd/_exit.o ctype/isalnum.o time/ctime_r.o stdlib/strtold.o sys/time/gettimeofday.o stdio/fgetpos.o stdio/fsetpos.o ctype/isprint.o stdlib/system.o stdio/tmpnam.o unistd/msleep.o stdlib/atof.o stdlib/strtod.o stdio/rename.o sys/stat/mkdir.o unistd/uptime.o unistd/ftruncate.o sys/socket/recvfrom.o sys/socket/sendto.o signal/kill.o signal/sigaction.o unistd/chdir.o unistd/getcwd.o stdio/getdelim.o stdio/getline.o unistd/isatty.o sys/socket/listen.o stdlib/realpath.o math/min.o math/max.o systemcall.o sys/random/randomfill.o
 all: libc.a
 
 %.o: %.c
diff --git a/userland/libc/include/sys/random.h b/userland/libc/include/sys/random.h
new file mode 100644
index 0000000..0be3dd8
--- /dev/null
+++ b/userland/libc/include/sys/random.h
@@ -0,0 +1,3 @@
+#include <stdint.h>
+
+void randomfill(void *buffer, uint32_t size);
diff --git a/userland/libc/include/syscall.h b/userland/libc/include/syscall.h
index c09eafb..7a3b50d 100644
--- a/userland/libc/include/syscall.h
+++ b/userland/libc/include/syscall.h
@@ -39,6 +39,7 @@
 #define SYS_CHDIR 31
 #define SYS_GETCWD 32
 #define SYS_ISATTY 33
+#define SYS_RANDOMFILL 34
 
 int syscall(uint32_t eax, uint32_t ebx, uint32_t ecx, uint32_t edx,
             uint32_t esi, uint32_t edi);
diff --git a/userland/libc/sys/random/randomfill.c b/userland/libc/sys/random/randomfill.c
new file mode 100644
index 0000000..18ec04d
--- /dev/null
+++ b/userland/libc/sys/random/randomfill.c
@@ -0,0 +1,6 @@
+#include <sys/random.h>
+#include <syscall.h>
+
+void randomfill(void *buffer, uint32_t size) {
+  syscall(SYS_RANDOMFILL, buffer, size, 0, 0, 0);
+}
diff --git a/userland/test/test.c b/userland/test/test.c
index a8c20dc..940854c 100644
--- a/userland/test/test.c
+++ b/userland/test/test.c
@@ -735,6 +735,26 @@ void realpath_test(void) {
   dbgln("realpath TEST PASSED");
 }
 
+void randomfill_test(void) {
+  dbgln("randomfill TEST");
+  {
+    char buffer[4096];
+    memset(buffer, 0, 4096);
+    randomfill(buffer, 4096);
+    int i;
+    for (i = 0; i < 4096; i++) {
+      if (0 != buffer[i])
+        break;
+    }
+    assert(4096 != i);
+    char buffer2[4096];
+    memcpy(buffer2, buffer, 4096);
+    randomfill(buffer, 4096);
+    assert(0 != memcmp(buffer, buffer2, 4096));
+  }
+  dbgln("randomfill TEST PASSED");
+}
+
 int main(void) {
   dbgln("START");
   malloc_test();
@@ -774,6 +794,7 @@ int main(void) {
   dirname_test();
   getline_test();
   realpath_test();
+  randomfill_test();
   // TODO: Add mkstemp
   return 0;
 }