v4.19.13 snapshot.
diff --git a/include/net/scm.h b/include/net/scm.h
new file mode 100644
index 0000000..1ce365f
--- /dev/null
+++ b/include/net/scm.h
@@ -0,0 +1,145 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_NET_SCM_H
+#define __LINUX_NET_SCM_H
+
+#include <linux/limits.h>
+#include <linux/net.h>
+#include <linux/cred.h>
+#include <linux/security.h>
+#include <linux/pid.h>
+#include <linux/nsproxy.h>
+#include <linux/sched/signal.h>
+
+/* Well, we should have at least one descriptor open
+ * to accept passed FDs 8)
+ */
+#define SCM_MAX_FD 253
+
+struct scm_creds {
+ u32 pid;
+ kuid_t uid;
+ kgid_t gid;
+};
+
+struct scm_fp_list {
+ short count;
+ short max;
+ struct user_struct *user;
+ struct file *fp[SCM_MAX_FD];
+};
+
+struct scm_cookie {
+ struct pid *pid; /* Skb credentials */
+ struct scm_fp_list *fp; /* Passed files */
+ struct scm_creds creds; /* Skb credentials */
+#ifdef CONFIG_SECURITY_NETWORK
+ u32 secid; /* Passed security ID */
+#endif
+};
+
+void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
+void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
+int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
+void __scm_destroy(struct scm_cookie *scm);
+struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl);
+
+#ifdef CONFIG_SECURITY_NETWORK
+static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
+{
+ security_socket_getpeersec_dgram(sock, NULL, &scm->secid);
+}
+#else
+static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
+{ }
+#endif /* CONFIG_SECURITY_NETWORK */
+
+static __inline__ void scm_set_cred(struct scm_cookie *scm,
+ struct pid *pid, kuid_t uid, kgid_t gid)
+{
+ scm->pid = get_pid(pid);
+ scm->creds.pid = pid_vnr(pid);
+ scm->creds.uid = uid;
+ scm->creds.gid = gid;
+}
+
+static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
+{
+ put_pid(scm->pid);
+ scm->pid = NULL;
+}
+
+static __inline__ void scm_destroy(struct scm_cookie *scm)
+{
+ scm_destroy_cred(scm);
+ if (scm->fp)
+ __scm_destroy(scm);
+}
+
+static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
+ struct scm_cookie *scm, bool forcecreds)
+{
+ memset(scm, 0, sizeof(*scm));
+ scm->creds.uid = INVALID_UID;
+ scm->creds.gid = INVALID_GID;
+ if (forcecreds)
+ scm_set_cred(scm, task_tgid(current), current_uid(), current_gid());
+ unix_get_peersec_dgram(sock, scm);
+ if (msg->msg_controllen <= 0)
+ return 0;
+ return __scm_send(sock, msg, scm);
+}
+
+#ifdef CONFIG_SECURITY_NETWORK
+static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
+{
+ char *secdata;
+ u32 seclen;
+ int err;
+
+ if (test_bit(SOCK_PASSSEC, &sock->flags)) {
+ err = security_secid_to_secctx(scm->secid, &secdata, &seclen);
+
+ if (!err) {
+ put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
+ security_release_secctx(secdata, seclen);
+ }
+ }
+}
+#else
+static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
+{ }
+#endif /* CONFIG_SECURITY_NETWORK */
+
+static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
+ struct scm_cookie *scm, int flags)
+{
+ if (!msg->msg_control) {
+ if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
+ msg->msg_flags |= MSG_CTRUNC;
+ scm_destroy(scm);
+ return;
+ }
+
+ if (test_bit(SOCK_PASSCRED, &sock->flags)) {
+ struct user_namespace *current_ns = current_user_ns();
+ struct ucred ucreds = {
+ .pid = scm->creds.pid,
+ .uid = from_kuid_munged(current_ns, scm->creds.uid),
+ .gid = from_kgid_munged(current_ns, scm->creds.gid),
+ };
+ put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
+ }
+
+ scm_destroy_cred(scm);
+
+ scm_passec(sock, msg, scm);
+
+ if (!scm->fp)
+ return;
+
+ scm_detach_fds(msg, scm);
+}
+
+
+#endif /* __LINUX_NET_SCM_H */
+