net/core/scm.c

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

File Facts

System
Linux kernel
Corpus path
net/core/scm.c
Extension
.c
Size
12613 bytes
Lines
553
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: operation-table or driver-model contract
Status
pattern 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

const struct proto_ops *ops = READ_ONCE(sock->ops);
	struct cmsghdr *cmsg;
	int err;

	for_each_cmsghdr(cmsg, msg) {
		err = -EINVAL;

		/* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
		/* The first check was omitted in <= 2.2.5. The reasoning was
		   that parser checks cmsg_len in any case, so that
		   additional check would be work duplication.
		   But if cmsg_level is not SOL_SOCKET, we do not check
		   for too short ancillary data object at all! Oops.
		   OK, let's add it...
		 */
		if (!CMSG_OK(msg, cmsg))
			goto error;

		if (cmsg->cmsg_level != SOL_SOCKET)
			continue;

		switch (cmsg->cmsg_type)
		{
		case SCM_RIGHTS:
			if (!ops || ops->family != PF_UNIX)
				goto error;
			err=scm_fp_copy(cmsg, &p->fp);
			if (err<0)
				goto error;
			break;
		case SCM_CREDENTIALS:
		{
			struct ucred creds;
			kuid_t uid;
			kgid_t gid;
			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
				goto error;
			memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
			err = scm_check_creds(&creds);
			if (err)
				goto error;

			if (!p->pid || pid_vnr(p->pid) != creds.pid) {
				struct pid *pid;
				err = -ESRCH;
				pid = find_get_pid(creds.pid);
				if (!pid)
					goto error;

				/* pass a struct pid reference from
				 * find_get_pid() to scm_replace_pid().
				 */
				err = scm_replace_pid(p, pid);
				if (err) {
					put_pid(pid);
					goto error;
				}
			}

			err = -EINVAL;
			uid = make_kuid(current_user_ns(), creds.uid);
			gid = make_kgid(current_user_ns(), creds.gid);
			if (!uid_valid(uid) || !gid_valid(gid))
				goto error;

			p->creds.uid = uid;
			p->creds.gid = gid;
			break;
		}
		default:
			goto error;
		}
	}

	if (p->fp && !p->fp->count)
	{
		kfree(p->fp);
		p->fp = NULL;
	}
	return 0;

error:
	scm_destroy(p);
	return err;
}
EXPORT_SYMBOL(__scm_send);

int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
{
	int cmlen = CMSG_LEN(len);

Annotation

Implementation Notes