socket32.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

	/* Copy back fixed up data, and adjust pointers. */
	bufsz = (wp - workbuf);
	copy_to_user((void *)orig_cmsg_uptr, workbuf, bufsz);

	kmsg->msg_control = (struct cmsghdr *)
		(((char *)orig_cmsg_uptr) + bufsz);
	kmsg->msg_controllen = space_avail - bufsz;

	kfree(workbuf);
	return;

fail:
	/* If we leave the 64-bit format CMSG chunks in there,
	 * the application could get confused and crash.  So to
	 * ensure greater recovery, we report no CMSGs.
	 */
	kmsg->msg_controllen += bufsz;
	kmsg->msg_control = (void *) orig_cmsg_uptr;
}

asmlinkage long sys32_sendmsg(int fd, struct msghdr32 *user_msg, unsigned user_flags)
{
	struct socket *sock;
	char address[MAX_SOCK_ADDR];
	struct iovec iov[UIO_FASTIOV];
	unsigned char ctl[sizeof(struct cmsghdr) + 20];
	unsigned char *ctl_buf = ctl;
	struct msghdr kern_msg;
	int err, total_len;

	if(msghdr_from_user32_to_kern(&kern_msg, user_msg))
		return -EFAULT;
	if(kern_msg.msg_iovlen > UIO_MAXIOV)
		return -EINVAL;
	err = verify_iovec32(&kern_msg, iov, address, VERIFY_READ);
	if (err < 0)
		goto out;
	total_len = err;

	if(kern_msg.msg_controllen) {
		err = cmsghdr_from_user32_to_kern(&kern_msg, ctl, sizeof(ctl));
		if(err)
			goto out_freeiov;
		ctl_buf = kern_msg.msg_control;
	}
	kern_msg.msg_flags = user_flags;

	sock = sockfd_lookup(fd, &err);
	if (sock != NULL) {
		if (sock->file->f_flags & O_NONBLOCK)
			kern_msg.msg_flags |= MSG_DONTWAIT;
		err = sock_sendmsg(sock, &kern_msg, total_len);
		sockfd_put(sock);
	}

	/* N.B. Use kfree here, as kern_msg.msg_controllen might change? */
	if(ctl_buf != ctl)
		kfree(ctl_buf);
out_freeiov:
	if(kern_msg.msg_iov != iov)
		kfree(kern_msg.msg_iov);
out:
	return err;
}

asmlinkage long sys32_recvmsg(int fd, struct msghdr32 *user_msg, unsigned int user_flags)
{
	struct iovec iovstack[UIO_FASTIOV];
	struct msghdr kern_msg;
	char addr[MAX_SOCK_ADDR];
	struct socket *sock;
	struct iovec *iov = iovstack;
	struct sockaddr *uaddr;
	int *uaddr_len;
	unsigned long cmsg_ptr;
	int err, total_len, len = 0;

	if(msghdr_from_user32_to_kern(&kern_msg, user_msg))
		return -EFAULT;
	if(kern_msg.msg_iovlen > UIO_MAXIOV)
		return -EINVAL;

	uaddr = kern_msg.msg_name;
	uaddr_len = &user_msg->msg_namelen;
	err = verify_iovec32(&kern_msg, iov, addr, VERIFY_WRITE);
	if (err < 0)
		goto out;
	total_len = err;

	cmsg_ptr = (unsigned long) kern_msg.msg_control;
	kern_msg.msg_flags = 0;

	sock = sockfd_lookup(fd, &err);
	if (sock != NULL) {
		struct scm_cookie scm;

		if (sock->file->f_flags & O_NONBLOCK)
			user_flags |= MSG_DONTWAIT;
		memset(&scm, 0, sizeof(scm));
		err = sock->ops->recvmsg(sock, &kern_msg, total_len,
					 user_flags, &scm);
		if(err >= 0) {
			len = err;
			if(!kern_msg.msg_control) {
				if(sock->passcred || scm.fp)
					kern_msg.msg_flags |= MSG_CTRUNC;
				if(scm.fp)
					__scm_destroy(&scm);
			} else {
				/* If recvmsg processing itself placed some
				 * control messages into user space, it's is
				 * using 64-bit CMSG processing, so we need
				 * to fix it up before we tack on more stuff.
				 */
				if((unsigned long) kern_msg.msg_control != cmsg_ptr)
					cmsg32_recvmsg_fixup(&kern_msg, cmsg_ptr);

				/* Wheee... */
				if(sock->passcred)
					put_cmsg32(&kern_msg,
						   SOL_SOCKET, SCM_CREDENTIALS,
						   sizeof(scm.creds), &scm.creds);
				if(scm.fp != NULL)
					scm_detach_fds32(&kern_msg, &scm);
			}
		}
		sockfd_put(sock);
	}

	if(uaddr != NULL && err >= 0)
		err = move_addr_to_user(addr, kern_msg.msg_namelen, uaddr, uaddr_len);
	if(cmsg_ptr != 0 && err >= 0) {
		unsigned long ucmsg_ptr = ((unsigned long)kern_msg.msg_control);
		__kernel_size_t32 uclen = (__kernel_size_t32) (ucmsg_ptr - cmsg_ptr);
		err |= __put_user(uclen, &user_msg->msg_controllen);
	}
	if(err >= 0)
		err = __put_user(kern_msg.msg_flags, &user_msg->msg_flags);
	if(kern_msg.msg_iov != iov)
		kfree(kern_msg.msg_iov);
out:
	if(err < 0)
		return err;
	return len;
}

extern asmlinkage int sys_setsockopt(int fd, int level, int optname,
				     char *optval, int optlen);

static int do_set_attach_filter(int fd, int level, int optname,
				char *optval, int optlen)
{
	struct sock_fprog32 {
		__u16 len;
		__u32 filter;
	} *fprog32 = (struct sock_fprog32 *)optval;
	struct sock_fprog kfprog;
	struct sock_filter *kfilter;
	unsigned int fsize;
	mm_segment_t old_fs;
	__u32 uptr;
	int ret;

	if (get_user(kfprog.len, &fprog32->len) ||
	    __get_user(uptr, &fprog32->filter))
		return -EFAULT;

	kfprog.filter = (struct sock_filter *)A(uptr);
	fsize = kfprog.len * sizeof(struct sock_filter);

	kfilter = (struct sock_filter *)kmalloc(fsize, GFP_KERNEL);
	if (kfilter == NULL)
		return -ENOMEM;

	if (copy_from_user(kfilter, kfprog.filter, fsize)) {
		kfree(kfilter);
		return -EFAULT;
	}

	kfprog.filter = kfilter;

	old_fs = get_fs();
	set_fs(KERNEL_DS);
	ret = sys_setsockopt(fd, level, optname,
			     (char *)&kfprog, sizeof(kfprog));
	set_fs(old_fs);

	kfree(kfilter);

	return ret;
}

static int do_set_icmpv6_filter(int fd, int level, int optname,
				char *optval, int optlen)
{
	struct icmp6_filter kfilter;
	mm_segment_t old_fs;
	int ret, i;

	if (copy_from_user(&kfilter, optval, sizeof(kfilter)))
		return -EFAULT;


	for (i = 0; i < 8; i += 2) {
		u32 tmp = kfilter.data[i];

		kfilter.data[i] = kfilter.data[i + 1];
		kfilter.data[i + 1] = tmp;
	}

	old_fs = get_fs();
	set_fs(KERNEL_DS);
	ret = sys_setsockopt(fd, level, optname,
			     (char *) &kfilter, sizeof(kfilter));
	set_fs(old_fs);

	return ret;
}

asmlinkage long sys32_setsockopt(int fd, int level, int optname,
				char *optval, int optlen)
{
	if (optname == SO_ATTACH_FILTER)
		return do_set_attach_filter(fd, level, optname,
					    optval, optlen);
	if (level == SOL_ICMPV6 && optname == ICMPV6_FILTER)
		return do_set_icmpv6_filter(fd, level, optname,
					    optval, optlen);

	return sys_setsockopt(fd, level, optname, optval, optlen);
}


/* Argument list sizes for sys_socketcall */
#define AL(x) ((x) * sizeof(u32))
static unsigned char nas[18]={AL(0),AL(3),AL(3),AL(3),AL(2),AL(3),
                                AL(3),AL(3),AL(4),AL(4),AL(4),AL(6),
                                AL(6),AL(2),AL(5),AL(5),AL(3),AL(3)};
#undef AL

extern asmlinkage long sys_bind(int fd, struct sockaddr *umyaddr, int addrlen);
extern asmlinkage long sys_connect(int fd, struct sockaddr *uservaddr,
				  int addrlen);
extern asmlinkage long sys_accept(int fd, struct sockaddr *upeer_sockaddr,
				 int *upeer_addrlen); 
extern asmlinkage long sys_getsockname(int fd, struct sockaddr *usockaddr,
				      int *usockaddr_len);
extern asmlinkage long sys_getpeername(int fd, struct sockaddr *usockaddr,
				      int *usockaddr_len);
extern asmlinkage long sys_send(int fd, void *buff, size_t len, unsigned flags);
extern asmlinkage long sys_sendto(int fd, u32 buff, __kernel_size_t32 len,
				   unsigned flags, u32 addr, int addr_len);
extern asmlinkage long sys_recv(int fd, void *ubuf, size_t size, unsigned flags);
extern asmlinkage long sys_recvfrom(int fd, u32 ubuf, __kernel_size_t32 size,
				     unsigned flags, u32 addr, u32 addr_len);
extern asmlinkage long sys_getsockopt(int fd, int level, int optname,
				       u32 optval, u32 optlen);

extern asmlinkage long sys_socket(int family, int type, int protocol);
extern asmlinkage long sys_socketpair(int family, int type, int protocol,
				     int usockvec[2]);
extern asmlinkage long sys_shutdown(int fd, int how);
extern asmlinkage long sys_listen(int fd, int backlog);

asmlinkage long sys32_socketcall(int call, u32 *args)
{
	int ret;
	u32 a[6];
	u32 a0,a1;
				 
	if (call<SYS_SOCKET||call>SYS_RECVMSG)
		return -EINVAL;
	if (copy_from_user(a, args, nas[call]))
		return -EFAULT;
	a0=a[0];
	a1=a[1];
	
	switch(call) 
	{
		case SYS_SOCKET:
			ret = sys_socket(a0, a1, a[2]);
			break;
		case SYS_BIND:
			ret = sys_bind(a0, (struct sockaddr *)A(a1), a[2]);
			break;
		case SYS_CONNECT:
			ret = sys_connect(a0, (struct sockaddr *)A(a1), a[2]);
			break;
		case SYS_LISTEN:
			ret = sys_listen(a0, a1);
			break;
		case SYS_ACCEPT:
			ret = sys_accept(a0, (struct sockaddr *)A(a1),
					  (int *)A(a[2]));
			break;
		case SYS_GETSOCKNAME:
			ret = sys_getsockname(a0, (struct sockaddr *)A(a1),
					       (int *)A(a[2]));
			break;
		case SYS_GETPEERNAME:
			ret = sys_getpeername(a0, (struct sockaddr *)A(a1),
					       (int *)A(a[2]));
			break;
		case SYS_SOCKETPAIR:
			ret = sys_socketpair(a0, a1, a[2], (int *)A(a[3]));
			break;
		case SYS_SEND:
			ret = sys_send(a0, (void *)A(a1), a[2], a[3]);
			break;
		case SYS_SENDTO:
			ret = sys_sendto(a0, a1, a[2], a[3], a[4], a[5]);
			break;
		case SYS_RECV:
			ret = sys_recv(a0, (void *)A(a1), a[2], a[3]);
			break;
		case SYS_RECVFROM:
			ret = sys_recvfrom(a0, a1, a[2], a[3], a[4], a[5]);
			break;
		case SYS_SHUTDOWN:
			ret = sys_shutdown(a0,a1);
			break;
		case SYS_SETSOCKOPT:
			ret = sys32_setsockopt(a0, a1, a[2], (char *)A(a[3]),
					      a[4]);
			break;
		case SYS_GETSOCKOPT:
			ret = sys_getsockopt(a0, a1, a[2], a[3], a[4]);
			break;
		case SYS_SENDMSG:
			ret = sys32_sendmsg(a0, (struct msghdr32 *)A(a1),
					     a[2]);
			break;
		case SYS_RECVMSG:
			ret = sys32_recvmsg(a0, (struct msghdr32 *)A(a1),
					     a[2]);
			break;
		default:
			ret = -EINVAL;
			break;
	}
	return ret;
}