System hardening and errno impl

8 files changed, 140 insertions, 9 deletions

diff --git a/libc/Makefile b/libc/Makefile
index 3bf4473..2dd2c5f 100644
--- a/libc/Makefile
+++ b/libc/Makefile
@@ -1,7 +1,8 @@
 # MIT License, Copyright (c) 2020 Marvin Borner
 
-# TODO: Remove serial and cpu from libc?
+# TODO: Remove cpu from libc?
 COBJS = sanitize.o \
+	errno.o \
 	str.o \
 	alloc.o \
 	mem.o \
diff --git a/libc/errno.c b/libc/errno.c
new file mode 100644
index 0000000..7204f5b
--- /dev/null
+++ b/libc/errno.c
@@ -0,0 +1,14 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <def.h>
+#include <errno.h>
+#ifdef userspace
+
+static u32 error = 0;
+
+u32 *__errno(void)
+{
+	return &error;
+}
+
+#endif
diff --git a/libc/inc/errno.h b/libc/inc/errno.h
new file mode 100644
index 0000000..76b4b85
--- /dev/null
+++ b/libc/inc/errno.h
@@ -0,0 +1,49 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#ifndef ERRNO_H
+#define ERRNO_H
+
+#include <def.h>
+
+#define EPERM 1 /* Operation not permitted */
+#define ENOENT 2 /* No such file or directory */
+#define ESRCH 3 /* No such process */
+#define EINTR 4 /* Interrupted system call */
+#define EIO 5 /* I/O error */
+#define ENXIO 6 /* No such device or address */
+#define E2BIG 7 /* Argument list too long */
+#define ENOEXEC 8 /* Exec format error */
+#define EBADF 9 /* Bad file number */
+#define ECHILD 10 /* No child processes */
+#define EAGAIN 11 /* Try again */
+#define ENOMEM 12 /* Out of memory */
+#define EACCES 13 /* Permission denied */
+#define EFAULT 14 /* Bad address */
+#define ENOTBLK 15 /* Block device required */
+#define EBUSY 16 /* Device or resource busy */
+#define EEXIST 17 /* File exists */
+#define EXDEV 18 /* Cross-device link */
+#define ENODEV 19 /* No such device */
+#define ENOTDIR 20 /* Not a directory */
+#define EISDIR 21 /* Is a directory */
+#define EINVAL 22 /* Invalid argument */
+#define ENFILE 23 /* File table overflow */
+#define EMFILE 24 /* Too many open files */
+#define ENOTTY 25 /* Not a typewriter */
+#define ETXTBSY 26 /* Text file busy */
+#define EFBIG 27 /* File too large */
+#define ENOSPC 28 /* No space left on device */
+#define ESPIPE 29 /* Illegal seek */
+#define EROFS 30 /* Read-only file system */
+#define EMLINK 31 /* Too many links */
+#define EPIPE 32 /* Broken pipe */
+#define EDOM 33 /* Math argument out of domain of func */
+#define ERANGE 34 /* Math result not representable */
+#define EMAX 35 /* Max errno */
+
+#ifdef userspace
+#define errno (*__errno())
+extern u32 *__errno(void);
+#endif
+
+#endif
diff --git a/libc/inc/str.h b/libc/inc/str.h
index 0ef49a6..d0a521f 100644
--- a/libc/inc/str.h
+++ b/libc/inc/str.h
@@ -17,4 +17,6 @@ int strncmp(const char *s1, const char *s2, u32 n);
 char *strinv(char *s);
 char *strdup(const char *s);
 
+const char *strerror(u32 err);
+
 #endif
diff --git a/libc/print.c b/libc/print.c
index 1c577e5..b687239 100644
--- a/libc/print.c
+++ b/libc/print.c
@@ -158,8 +158,10 @@ int print(const char *str)
 
 // The kernel prints everything into the serial console
 
+#include <mm.h>
 #include <proc.h>
 #include <serial.h>
+
 #define RED "\x1B[1;31m"
 #define GRN "\x1B[1;32m"
 #define YEL "\x1B[1;33m"
@@ -223,6 +225,8 @@ void print_trace(u32 count)
 	__asm__ volatile("movl %%ebp, %0;" : "=r"(stk));
 	print("EBP\tEIP\n");
 	for (u32 i = 0; stk && i < count; i++) {
+		/* u32 eip = memory_valid((void *)stk->eip) ? stk->eip : stk->eip + 64; */
+		/* printf("0x%x\t0x%x\n", stk->ebp, eip); */
 		printf("0x%x\t0x%x\n", stk->ebp, stk->eip);
 		stk = stk->ebp;
 	}
@@ -240,6 +244,7 @@ NORETURN void panic(const char *format, ...)
 #ifdef kernel
 	print("--- DON'T PANIC! ---\n");
 	print(buf);
+	print_trace(5);
 	loop();
 #else
 	err(1, buf);
diff --git a/libc/random.c b/libc/random.c
index cfd082d..2801029 100644
--- a/libc/random.c
+++ b/libc/random.c
@@ -19,7 +19,10 @@ u32 rdrand(void)
 		return rand();
 
 	u32 rd;
-	__asm__ volatile("rdrand %%eax" : "=a"(rd));
+	__asm__ volatile("1:\n"
+			 "rdrand %0\n"
+			 "jnc 1b\n"
+			 : "=r"(rd));
 	return rd;
 #else
 	return rand();
@@ -33,7 +36,10 @@ u32 rdseed(void)
 		return rand();
 
 	u32 rd;
-	__asm__ volatile("rdseed %%eax" : "=a"(rd));
+	__asm__ volatile("1:\n"
+			 "rdseed %0\n"
+			 "jnc 1b\n"
+			 : "=r"(rd));
 	return rd;
 #else
 	return rand();
diff --git a/libc/str.c b/libc/str.c
index 13ac27f..54be4f6 100644
--- a/libc/str.c
+++ b/libc/str.c
@@ -1,6 +1,7 @@
 // MIT License, Copyright (c) 2020 Marvin Borner
 
 #include <def.h>
+#include <errno.h>
 #include <mem.h>
 #include <str.h>
 
@@ -124,3 +125,48 @@ char *strdup(const char *s)
 
 	return d;
 }
+
+static const char *strerrors[EMAX] = {
+	"Success",
+	"Operation not permitted",
+	"No such file or directory",
+	"No such process",
+	"Interrupted system call",
+	"I/O error",
+	"No such device or address",
+	"Argument list too long",
+	"Exec format error",
+	"Bad file number",
+	"No child processes",
+	"Try again",
+	"Out of memory",
+	"Permission denied",
+	"Bad address",
+	"Block device required",
+	"Device or resource busy",
+	"File exists",
+	"Cross-device link",
+	"No such device",
+	"Not a directory",
+	"Is a directory",
+	"Invalid argument",
+	"File table overflow",
+	"Too many open files",
+	"Not a typewriter",
+	"Text file busy",
+	"File too large",
+	"No space left on device",
+	"Illegal seek",
+	"Read-only file system",
+	"Too many links",
+	"Broken pipe",
+	"Math argument out of domain of func",
+	"Math result not representable",
+};
+
+const char *strerror(u32 error)
+{
+	if (error <= EMAX)
+		return strerrors[error];
+	return "Unknown error";
+}
diff --git a/libc/sys.c b/libc/sys.c
index 83f385b..330b500 100644
--- a/libc/sys.c
+++ b/libc/sys.c
@@ -2,6 +2,7 @@
 // Syscall implementation
 
 #include <arg.h>
+#include <errno.h>
 #include <sys.h>
 
 #if defined(userspace)
@@ -10,25 +11,32 @@
  * Definitions
  */
 
+#define ERRIFY(ret)                                                                                \
+	if (ret < 0) {                                                                             \
+		errno = -ret;                                                                      \
+		return -1;                                                                         \
+	}                                                                                          \
+	return ret
+
 int sys0(enum sys num)
 {
 	int a;
 	__asm__ volatile("int $0x80" : "=a"(a) : "0"(num));
-	return a;
+	ERRIFY(a);
 }
 
 int sys1(enum sys num, int d1)
 {
 	int a;
 	__asm__ volatile("int $0x80" : "=a"(a) : "0"(num), "b"((int)d1));
-	return a;
+	ERRIFY(a);
 }
 
 int sys2(enum sys num, int d1, int d2)
 {
 	int a;
 	__asm__ volatile("int $0x80" : "=a"(a) : "0"(num), "b"((int)d1), "c"((int)d2));
-	return a;
+	ERRIFY(a);
 }
 
 int sys3(enum sys num, int d1, int d2, int d3)
@@ -37,7 +45,7 @@ int sys3(enum sys num, int d1, int d2, int d3)
 	__asm__ volatile("int $0x80"
 			 : "=a"(a)
 			 : "0"(num), "b"((int)d1), "c"((int)d2), "d"((int)d3));
-	return a;
+	ERRIFY(a);
 }
 
 int sys4(enum sys num, int d1, int d2, int d3, int d4)
@@ -46,7 +54,7 @@ int sys4(enum sys num, int d1, int d2, int d3, int d4)
 	__asm__ volatile("int $0x80"
 			 : "=a"(a)
 			 : "0"(num), "b"((int)d1), "c"((int)d2), "d"((int)d3), "S"((int)d4));
-	return a;
+	ERRIFY(a);
 }
 
 int sys5(enum sys num, int d1, int d2, int d3, int d4, int d5)
@@ -56,7 +64,7 @@ int sys5(enum sys num, int d1, int d2, int d3, int d4, int d5)
 			 : "=a"(a)
 			 : "0"(num), "b"((int)d1), "c"((int)d2), "d"((int)d3), "S"((int)d4),
 			   "D"((int)d5));
-	return a;
+	ERRIFY(a);
 }
 
 int sysv(enum sys num, ...)