netdump: send key before dump, in case dump fails

Previously, if an encrypted netdump failed, such as due to a timeout or
network failure, the key was not saved, so a partial dump was
completely useless.

Send the key first, so the partial dump can be decrypted, because even a
partial dump can be useful.

Reviewed by:	bdrewery, markj
MFC after:	1 week
Sponsored by:	Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D31453

3 files changed, 43 insertions, 24 deletions

diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c
index fb2a69401801..3cc51fd31956 100644
--- a/sys/kern/kern_shutdown.c
+++ b/sys/kern/kern_shutdown.c
@@ -1488,7 +1488,7 @@ dump_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh)
 #ifdef EKCD
 	struct kerneldumpcrypto *kdc;
 #endif
-	void *buf, *key;
+	void *buf;
 	size_t hdrsz;
 	uint64_t extent;
 	uint32_t keysize;
@@ -1500,10 +1500,8 @@ dump_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh)
 
 #ifdef EKCD
 	kdc = di->kdcrypto;
-	key = kdc->kdc_dumpkey;
 	keysize = kerneldumpcrypto_dumpkeysize(kdc);
 #else
-	key = NULL;
 	keysize = 0;
 #endif
 
@@ -1512,7 +1510,7 @@ dump_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh)
 	 * of writing them out.
 	 */
 	if (di->dumper_hdr != NULL)
-		return (di->dumper_hdr(di, kdh, key, keysize));
+		return (di->dumper_hdr(di, kdh));
 
 	if (hdrsz == di->blocksize)
 		buf = kdh;
@@ -1571,22 +1569,30 @@ dump_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh)
 int
 dump_start(struct dumperinfo *di, struct kerneldumpheader *kdh)
 {
+#ifdef EKCD
+	struct kerneldumpcrypto *kdc;
+#endif
+	void *key;
 	uint64_t dumpextent, span;
 	uint32_t keysize;
 	int error;
 
 #ifdef EKCD
-	error = kerneldumpcrypto_init(di->kdcrypto);
+	/* Send the key before the dump so a partial dump is still usable. */
+	kdc = di->kdcrypto;
+	error = kerneldumpcrypto_init(kdc);
 	if (error != 0)
 		return (error);
-	keysize = kerneldumpcrypto_dumpkeysize(di->kdcrypto);
+	keysize = kerneldumpcrypto_dumpkeysize(kdc);
+	key = keysize > 0 ? kdc->kdc_dumpkey : NULL;
 #else
 	error = 0;
 	keysize = 0;
+	key = NULL;
 #endif
 
 	if (di->dumper_start != NULL) {
-		error = di->dumper_start(di);
+		error = di->dumper_start(di, key, keysize);
 	} else {
 		dumpextent = dtoh64(kdh->dumpextent);
 		span = SIZEOF_METADATA + dumpextent + 2 * di->blocksize +
diff --git a/sys/netinet/netdump/netdump_client.c b/sys/netinet/netdump/netdump_client.c
index 2669ec879d75..d6fd7db364b8 100644
--- a/sys/netinet/netdump/netdump_client.c
+++ b/sys/netinet/netdump/netdump_client.c
@@ -95,7 +95,8 @@ static int	 netdump_enabled_sysctl(SYSCTL_HANDLER_ARGS);
 static int	 netdump_ioctl(struct cdev *dev __unused, u_long cmd,
 		    caddr_t addr, int flags __unused, struct thread *td);
 static int	 netdump_modevent(module_t mod, int type, void *priv);
-static int	 netdump_start(struct dumperinfo *di);
+static int	 netdump_start(struct dumperinfo *di, void *key,
+		    uint32_t keysize);
 static void	 netdump_unconfigure(void);
 
 /* Must be at least as big as the chunks dumpsys() gives us. */
@@ -285,7 +286,7 @@ netdump_dumper(void *priv __unused, void *virtual,
  * Perform any initialization needed prior to transmitting the kernel core.
  */
 static int
-netdump_start(struct dumperinfo *di)
+netdump_start(struct dumperinfo *di, void *key, uint32_t keysize)
 {
 	struct debugnet_conn_params dcp;
 	struct debugnet_pcb *pcb;
@@ -336,12 +337,34 @@ netdump_start(struct dumperinfo *di)
 	printf("netdumping to %s (%6D)\n", inet_ntoa_r(nd_server, buf),
 	    debugnet_get_gw_mac(pcb), ":");
 	nd_conf.nd_pcb = pcb;
-	return (0);
+
+	/* Send the key before the dump so a partial dump is still usable. */
+	if (keysize > 0) {
+		if (keysize > sizeof(nd_buf)) {
+			printf("crypto key is too large (%u)\n", keysize);
+			error = EINVAL;
+			goto out;
+		}
+		memcpy(nd_buf, key, keysize);
+		error = debugnet_send(pcb, NETDUMP_EKCD_KEY, nd_buf, keysize,
+		    NULL);
+		if (error != 0) {
+			printf("error %d sending crypto key\n", error);
+			goto out;
+		}
+	}
+
+out:
+	if (error != 0) {
+		/* As above, squash errors. */
+		error = EINVAL;
+		netdump_cleanup();
+	}
+	return (error);
 }
 
 static int
-netdump_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh,
-    void *key, uint32_t keysize)
+netdump_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh)
 {
 	int error;
 
@@ -351,15 +374,6 @@ netdump_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh,
 	memcpy(nd_buf, kdh, sizeof(*kdh));
 	error = debugnet_send(nd_conf.nd_pcb, NETDUMP_KDH, nd_buf,
 	    sizeof(*kdh), NULL);
-	if (error == 0 && keysize > 0) {
-		if (keysize > sizeof(nd_buf)) {
-			error = EINVAL;
-			goto out;
-		}
-		memcpy(nd_buf, key, keysize);
-		error = debugnet_send(nd_conf.nd_pcb, NETDUMP_EKCD_KEY, nd_buf,
-		    keysize, NULL);
-	}
 out:
 	if (error != 0)
 		netdump_cleanup();
diff --git a/sys/sys/conf.h b/sys/sys/conf.h
index 123bf91cf952..053cf6ddb016 100644
--- a/sys/sys/conf.h
+++ b/sys/sys/conf.h
@@ -133,9 +133,8 @@ typedef int dumper_t(
 	vm_offset_t _physical,	/* Physical address of virtual. */
 	off_t _offset,		/* Byte-offset to write at. */
 	size_t _length);	/* Number of bytes to dump. */
-typedef int dumper_start_t(struct dumperinfo *di);
-typedef int dumper_hdr_t(struct dumperinfo *di, struct kerneldumpheader *kdh,
-    void *key, uint32_t keylen);
+typedef int dumper_start_t(struct dumperinfo *di, void *key, uint32_t keysize);
+typedef int dumper_hdr_t(struct dumperinfo *di, struct kerneldumpheader *kdh);
 
 #endif /* _KERNEL */