Introduced SCM_CREDENTIALS / SCM_CREDS in the socket control msgs.

1 files changed, 220 insertions, 0 deletions

diff --git a/src/nxt_socket_msg.h b/src/nxt_socket_msg.h
new file mode 100644
index 00000000..04de1761
--- /dev/null
+++ b/src/nxt_socket_msg.h
@@ -0,0 +1,220 @@
+/*
+ * Copyright (C) NGINX, Inc.
+ */
+
+#ifndef _NXT_SOCKET_MSG_H_INCLUDED_
+#define _NXT_SOCKET_MSG_H_INCLUDED_
+
+#if (NXT_HAVE_UCRED)
+#include <sys/un.h>
+#endif
+
+
+#if (NXT_HAVE_UCRED)
+#define NXT_CRED_USECMSG    1
+#define NXT_CRED_CMSGTYPE   SCM_CREDENTIALS
+#define NXT_CRED_GETPID(u)  (u->pid)
+
+typedef struct ucred        nxt_socket_cred_t;
+
+#elif (NXT_HAVE_MSGHDR_CMSGCRED)
+#define NXT_CRED_USECMSG    1
+#define NXT_CRED_CMSGTYPE   SCM_CREDS
+#define NXT_CRED_GETPID(u)  (u->cmcred_pid)
+
+typedef struct cmsgcred     nxt_socket_cred_t;
+#endif
+
+#if (NXT_CRED_USECMSG)
+#define NXT_OOB_RECV_SIZE                                                     \
+    (CMSG_SPACE(2 * sizeof(int)) + CMSG_SPACE(sizeof(nxt_socket_cred_t)))
+#else
+#define NXT_OOB_RECV_SIZE                                                     \
+    CMSG_SPACE(2 * sizeof(int))
+#endif
+
+#if (NXT_HAVE_MSGHDR_CMSGCRED)
+#define NXT_OOB_SEND_SIZE                                                     \
+    (CMSG_SPACE(2 * sizeof(int)) + CMSG_SPACE(sizeof(nxt_socket_cred_t)))
+#else
+#define NXT_OOB_SEND_SIZE                                                     \
+    CMSG_SPACE(2 * sizeof(int))
+#endif
+
+
+typedef struct {
+    size_t  size;
+    u_char  buf[NXT_OOB_RECV_SIZE];
+} nxt_recv_oob_t;
+
+
+typedef struct {
+    size_t  size;
+    u_char  buf[NXT_OOB_SEND_SIZE];
+} nxt_send_oob_t;
+
+
+/**
+ * The nxt_sendmsg is a wrapper for sendmsg.
+ * The oob struct must be initialized using nxt_socket_msg_oob_init().
+ */
+NXT_EXPORT ssize_t nxt_sendmsg(nxt_socket_t s, nxt_iobuf_t *iob,
+    nxt_uint_t niob, const nxt_send_oob_t *oob);
+
+/**
+ * The nxt_recvmsg is a wrapper for recvmsg.
+ * The oob buffer must be consumed by using nxt_socket_msg_oob_get().
+ */
+NXT_EXPORT ssize_t nxt_recvmsg(nxt_socket_t s,
+    nxt_iobuf_t *iob, nxt_uint_t niob, nxt_recv_oob_t *oob);
+
+
+nxt_inline void
+nxt_socket_msg_oob_init(nxt_send_oob_t *oob, int *fds)
+{
+    int             nfds;
+    struct cmsghdr  *cmsg;
+
+#if (NXT_HAVE_MSGHDR_CMSGCRED)
+    cmsg = (struct cmsghdr *) (oob->buf);
+    /*
+     * Fill all padding fields with 0.
+     * Code in Go 1.11 validate cmsghdr using padding field as part of len.
+     * See Cmsghdr definition and socketControlMessageHeaderAndData function.
+     */
+    nxt_memzero(cmsg, sizeof(struct cmsghdr));
+
+    cmsg->cmsg_len = CMSG_LEN(sizeof(nxt_socket_cred_t));
+    cmsg->cmsg_level = SOL_SOCKET;
+    cmsg->cmsg_type = NXT_CRED_CMSGTYPE;
+
+    oob->size = CMSG_SPACE(sizeof(nxt_socket_cred_t));
+
+#else
+    oob->size = 0;
+#endif
+
+    nfds = (fds[0] != -1 ? 1 : 0) + (fds[1] != -1 ? 1 : 0);
+
+    if (nfds == 0) {
+        return;
+    }
+
+    cmsg = (struct cmsghdr *) (oob->buf + oob->size);
+
+    nxt_memzero(cmsg, sizeof(struct cmsghdr));
+
+    cmsg->cmsg_len = CMSG_LEN(nfds * sizeof(int));
+    cmsg->cmsg_level = SOL_SOCKET;
+    cmsg->cmsg_type = SCM_RIGHTS;
+
+    /*
+     * nxt_memcpy() is used instead of simple
+     *   *(int *) CMSG_DATA(&cmsg.cm) = fd;
+     * because GCC 4.4 with -O2/3/s optimization may issue a warning:
+     *   dereferencing type-punned pointer will break strict-aliasing rules
+     *
+     * Fortunately, GCC with -O1 compiles this nxt_memcpy()
+     * in the same simple assignment as in the code above.
+     */
+    nxt_memcpy(CMSG_DATA(cmsg), fds, nfds * sizeof(int));
+
+    oob->size += CMSG_SPACE(nfds * sizeof(int));
+}
+
+
+nxt_inline nxt_int_t
+nxt_socket_msg_oob_get_fds(nxt_recv_oob_t *oob, nxt_fd_t *fd)
+{
+    size_t          size;
+    struct msghdr   msg;
+    struct cmsghdr  *cmsg;
+
+    msg.msg_control = oob->buf;
+    msg.msg_controllen = oob->size;
+
+    for (cmsg = CMSG_FIRSTHDR(&msg);
+         cmsg != NULL;
+         cmsg = CMSG_NXTHDR(&msg, cmsg))
+    {
+        size = cmsg->cmsg_len - CMSG_LEN(0);
+
+        if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
+            if (nxt_slow_path(size != sizeof(int) && size != 2 * sizeof(int))) {
+                return NXT_ERROR;
+            }
+
+            nxt_memcpy(fd, CMSG_DATA(cmsg), size);
+
+            return NXT_OK;
+        }
+    }
+
+    return NXT_OK;
+}
+
+
+nxt_inline nxt_int_t
+nxt_socket_msg_oob_get(nxt_recv_oob_t *oob, nxt_fd_t *fd, nxt_pid_t *pid)
+{
+    size_t          size;
+    struct msghdr   msg;
+    struct cmsghdr  *cmsg;
+
+    if (oob->size == 0) {
+        return NXT_OK;
+    }
+
+#if (NXT_CRED_USECMSG)
+    *pid = -1;
+#endif
+
+    msg.msg_control = oob->buf;
+    msg.msg_controllen = oob->size;
+
+    for (cmsg = CMSG_FIRSTHDR(&msg);
+         cmsg != NULL;
+         cmsg = CMSG_NXTHDR(&msg, cmsg))
+    {
+        size = cmsg->cmsg_len - CMSG_LEN(0);
+
+        if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
+            if (nxt_slow_path(size != sizeof(int) && size != 2 * sizeof(int))) {
+                return NXT_ERROR;
+            }
+
+            nxt_memcpy(fd, CMSG_DATA(cmsg), size);
+
+#if (!NXT_CRED_USECMSG)
+            break;
+#endif
+        }
+
+#if (NXT_CRED_USECMSG)
+        else if (cmsg->cmsg_level == SOL_SOCKET
+                 && cmsg->cmsg_type == NXT_CRED_CMSGTYPE)
+        {
+            nxt_socket_cred_t  *creds;
+
+            if (nxt_slow_path(size != sizeof(nxt_socket_cred_t))) {
+                return NXT_ERROR;
+            }
+
+            creds = (nxt_socket_cred_t *) CMSG_DATA(cmsg);
+            *pid = NXT_CRED_GETPID(creds);
+        }
+#endif
+    }
+
+#if (NXT_CRED_USECMSG)
+    /* For platforms supporting credential passing, it's enforced */
+    if (nxt_slow_path(*pid == -1)) {
+        return NXT_ERROR;
+    }
+#endif
+
+    return NXT_OK;
+}
+
+
+#endif /* _NXT_SOCKET_MSG_H_INCLUDED_ */