🚀 go-pugleaf

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He escrito este LKM. Es un patch para la syscall write, que pretende 
usar esta syscall para comunicarse con el kernel... pero a veces provoca 
Oops y desconozco por qu�. Incluyo el source a continuacion por si 
alguien ve el error o simplemente tiene curiosidad :).

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tuxisuau, tuxisuau@7a69ezine.org
http://tuxisuau.7a69ezine.org

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 filename="tuxwrite.c"

#define __KERNEL__
#define MODULE

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/mm.h>
#include <linux/ctype.h>
#include <asm/unistd.h>

#define MAGIC_MSG "magic \0"

extern void *sys_call_table[];
int (*o_write)(int, char *, int);

int tux_write(int fd, char *buf, int count) {
	int argc=0,c,quotes=0,arg,ptrarg;
	char **argv=NULL;
	char *buf_kernel=NULL;
	if ((buf_kernel=(char *)kmalloc(count,GFP_KERNEL))) {
		__generic_copy_from_user(buf_kernel, buf, count);
		if (!strncmp(buf_kernel, MAGIC_MSG, strlen(MAGIC_MSG))) {
			for (c=strlen(MAGIC_MSG)+1;c<=count;c++){
				if (buf_kernel[c]=='\n'){
					argc++;
					break;
				}
				if (quotes==0){
					if(buf_kernel[c]==34)
						quotes=1;
					if(buf_kernel[c]==' ')
						argc++;
				}
				else {
					if(buf_kernel[c]==34)
						quotes=0;
				}
			}
			if(quotes==1)
				argc=0;
			printk("detected %d arguments\n",argc);
			if (argc>0) {
				if ((argv=(char **)kmalloc(4*argc))) {
					printk("parsing arguments\n");
					c=strlen(MAGIC_MSG)-1;
					quotes=0;
					for(arg=0;arg<argc;arg++) {
						c++;
						if (quotes==1)
							c++;
						if (buf_kernel[c]==34){
							c++;
							quotes=1;
						}
						else
							quotes=0;
						ptrarg=c;
						if (quotes==0)
							while(!((buf_kernel[c]==' ')||(buf_kernel[c]=='\n')))
								c++;
						else
							while(!((buf_kernel[c]==34)||(buf_kernel[c]=='\n')))
								c++;
						printk("Allocating RAM for ARG\n");
						argv[arg]=(char *)kmalloc(c+1-ptrarg,GFP_KERNEL);
						memset(argv[arg],0,c+1-ptrarg);
						printk("Copying ARG\n");
						strncpy(argv[arg],(buf_kernel+ptrarg),c-ptrarg);
					}		
				}
				printk("\n");
				for(arg=0;arg<argc;arg++)
					printk("Arg: %d Data: %s\n",arg,argv[arg]);
				printk("Freeing RAM\n");
				for(arg=0;arg<argc;arg++)
					kfree(argv[arg]);
				kfree(argv);
			}
		}
	}		
	kfree(buf_kernel);
	return (*o_write)(fd,buf,count);
}

int init_module() {
	o_write=sys_call_table[__NR_write];
	sys_call_table[__NR_write]=tux_write;
	printk("Tux Write() patch installed!\n");
	return 0;
}

void cleanup_module() {
	sys_call_table[__NR_write]=o_write;
	printk("Tux Write() patch removed!\n");
}

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