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Subject[PATCH] ptrace PTRACE_READDATA/WRITEDATA, kernel 2.5.62
Hi,

I ported some generic SunOS ptrace requests from my 2.4 exptrace kernel
patch to the 2.5 tree. The PTRACE_READDATA/WRITEDATA requests have been
available for a long time for the sparc architecture but I think they're
also very useful on the i386 arch since PTRACE_PEEKDATA/POKEDATA are way
too slow when handling large data blocks.

Frank.

diff -Nur linux-2.5.62.orig/arch/i386/kernel/ptrace.c linux-2.5.62/arch/i386/kernel/ptrace.c
--- linux-2.5.62.orig/arch/i386/kernel/ptrace.c 2003-02-17 23:56:10.000000000 +0100
+++ linux-2.5.62/arch/i386/kernel/ptrace.c 2003-02-24 14:12:02.000000000 +0100
@@ -229,7 +229,7 @@
return 0;
}

-asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
+asmlinkage int sys_ptrace(long request, long pid, long addr, long data, long addr2)
{
struct task_struct *child;
struct user * dummy = NULL;
@@ -355,6 +355,34 @@
}
break;

+ case PTRACE_READDATA:
+ case PTRACE_READTEXT: {
+ int res;
+ ret = 0;
+ res = ptrace_readdata(child, addr, (void *)addr2, data);
+ if (res == data)
+ break;
+ if (res >= 0)
+ ret = -EIO;
+ else
+ ret = res;
+ break;
+ }
+
+ case PTRACE_WRITEDATA:
+ case PTRACE_WRITETEXT: {
+ int res;
+ ret = 0;
+ res = ptrace_writedata(child, (void *)addr2, addr, data);
+ if (res == data)
+ break;
+ if (res >= 0)
+ ret = -EIO;
+ else
+ ret = res;
+ break;
+ }
+
case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
case PTRACE_CONT: { /* restart after signal. */
long tmp;
diff -Nur linux-2.5.62.orig/include/asm-i386/ptrace.h linux-2.5.62/include/asm-i386/ptrace.h
--- linux-2.5.62.orig/include/asm-i386/ptrace.h 2003-02-17 23:55:51.000000000 +0100
+++ linux-2.5.62/include/asm-i386/ptrace.h 2003-02-24 13:54:33.000000000 +0100
@@ -53,6 +53,10 @@

#define PTRACE_GET_THREAD_AREA 25
#define PTRACE_SET_THREAD_AREA 26
+#define PTRACE_READDATA 27
+#define PTRACE_WRITEDATA 28
+#define PTRACE_READTEXT 29
+#define PTRACE_WRITETEXT 30

#ifdef __KERNEL__
#define user_mode(regs) ((VM_MASK & (regs)->eflags) || (3 & (regs)->xcs))
-----------------------------------------------------------------------
Demo:
#include <stdio.h>
#include <stdlib.h>
#include <sys/ptrace.h>
#include <asm/ptrace.h>
#include <sys/wait.h>
#include <sched.h>
#include <syscall.h>
#include <errno.h>
#define STACK_SIZE (1024*2)

#define DATA_SIZE (1024*64)

#ifndef __NR_ptrace5
#define __NR_ptrace5 __NR_ptrace
#endif

// we need to pass 5 parameters to PTRACE_READDATA/WRITEDATA
_syscall5 (int, ptrace5, int, request, pid_t, pid, void *, addr, void *, data,
void *, addr2);

static int child_func(void *param);
static volatile int go = 0;
static char *common_data;

int main()
{
int status, pid, i;
char *stack, *buf;
stack = malloc(STACK_SIZE);
common_data = malloc(DATA_SIZE);
srand(0);
for (i = 0; i < DATA_SIZE; i++)
common_data[i] = (int)(255.0 * rand() / (RAND_MAX + 1.0));
pid = clone(child_func, stack + STACK_SIZE, SIGCHLD | CLONE_VM, NULL);
ptrace(PTRACE_ATTACH, pid, NULL, NULL);
waitpid(pid, &status, 0);
go = 1;
buf = malloc(DATA_SIZE);
for (i = 0; i < DATA_SIZE; i++)
buf[i] = '\0';
while (1) {
ptrace(PTRACE_SYSCALL, pid, NULL, NULL);
waitpid(pid, &status, 0);
if (WIFEXITED(status))
exit(0);
if (WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) {
printf("syscall: %d (EAX: %d)\n",
(int)ptrace(PTRACE_PEEKUSER, pid, ORIG_EAX * 4, NULL),
(int)ptrace(PTRACE_PEEKUSER, pid, EAX * 4, NULL));
if (ptrace5(PTRACE_READDATA, pid, common_data, (void *)DATA_SIZE, buf)) {
perror("PTRACE_READDATA");
exit(1);
}
for (i = 0; i < DATA_SIZE; i++)
if (buf[i] != common_data[i]) {
fprintf(stderr, "PTRACE_READDATA error.\n");
exit(1);
}
}
}
}
static int child_func(void *param)
{
while (!go) ;
getpid();
getppid();
return 0;
}
-
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