net/compat.c

Source file repositories/reference/linux-study-clean/net/compat.c

File Facts

System
Linux kernel
Corpus path
net/compat.c
Extension
.c
Size
14531 bytes
Lines
519
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: implementation source
Status
source implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Dependency Surface

Detected Declarations

Annotated Snippet

if (!save_addr) {
			err = move_addr_to_kernel(compat_ptr(msg->msg_name),
						  kmsg->msg_namelen,
						  kmsg->msg_name);
			if (err < 0)
				return err;
		}
	} else {
		kmsg->msg_name = NULL;
		kmsg->msg_namelen = 0;
	}

	if (msg->msg_iovlen > UIO_MAXIOV)
		return -EMSGSIZE;

	kmsg->msg_ubuf = NULL;
	return 0;
}

int get_compat_msghdr(struct msghdr *kmsg,
		      struct compat_msghdr __user *umsg,
		      struct sockaddr __user **save_addr,
		      struct iovec **iov)
{
	struct compat_msghdr msg;
	ssize_t err;

	if (copy_from_user(&msg, umsg, sizeof(*umsg)))
		return -EFAULT;

	err = __get_compat_msghdr(kmsg, &msg, save_addr);
	if (err)
		return err;

	err = import_iovec(save_addr ? ITER_DEST : ITER_SOURCE,
			   compat_ptr(msg.msg_iov), msg.msg_iovlen,
			   UIO_FASTIOV, iov, &kmsg->msg_iter);
	return err < 0 ? err : 0;
}

/* Bleech... */
#define CMSG_COMPAT_ALIGN(len)	ALIGN((len), sizeof(s32))

#define CMSG_COMPAT_DATA(cmsg)				\
	((void __user *)((char __user *)(cmsg) + sizeof(struct compat_cmsghdr)))
#define CMSG_COMPAT_SPACE(len)				\
	(sizeof(struct compat_cmsghdr) + CMSG_COMPAT_ALIGN(len))
#define CMSG_COMPAT_LEN(len)				\
	(sizeof(struct compat_cmsghdr) + (len))

#define CMSG_COMPAT_FIRSTHDR(msg)			\
	(((msg)->msg_controllen) >= sizeof(struct compat_cmsghdr) ?	\
	 (struct compat_cmsghdr __user *)((msg)->msg_control_user) :	\
	 (struct compat_cmsghdr __user *)NULL)

#define CMSG_COMPAT_OK(ucmlen, ucmsg, mhdr) \
	((ucmlen) >= sizeof(struct compat_cmsghdr) && \
	 (ucmlen) <= (unsigned long) \
	 ((mhdr)->msg_controllen - \
	  ((char __user *)(ucmsg) - (char __user *)(mhdr)->msg_control_user)))

static inline struct compat_cmsghdr __user *cmsg_compat_nxthdr(struct msghdr *msg,
		struct compat_cmsghdr __user *cmsg, int cmsg_len)
{
	char __user *ptr = (char __user *)cmsg + CMSG_COMPAT_ALIGN(cmsg_len);
	if ((unsigned long)(ptr + 1 - (char __user *)msg->msg_control_user) >
			msg->msg_controllen)
		return NULL;
	return (struct compat_cmsghdr __user *)ptr;
}

/* There is a lot of hair here because the alignment rules (and
 * thus placement) of cmsg headers and length are different for
 * 32-bit apps.  -DaveM
 */
int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg, struct sock *sk,
			       unsigned char *stackbuf, int stackbuf_size)
{
	struct compat_cmsghdr __user *ucmsg;
	struct cmsghdr *kcmsg, *kcmsg_base;
	compat_size_t ucmlen;
	__kernel_size_t kcmlen, tmp;
	int err = -EFAULT;

	BUILD_BUG_ON(sizeof(struct compat_cmsghdr) !=
		     CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)));

	kcmlen = 0;
	kcmsg_base = kcmsg = (struct cmsghdr *)stackbuf;
	ucmsg = CMSG_COMPAT_FIRSTHDR(kmsg);

Annotation

Implementation Notes