From 372557d8c3d37dd0c1d9be56513a436393963848 Mon Sep 17 00:00:00 2001
From: Bryan Drewery <bdrewery@FreeBSD.org>
Date: Wed, 21 Jul 2021 17:37:03 -0700
Subject: [PATCH] dumpon: Fix -v causing error when configuring an encrypted
 dump

If -v is specified when adding a new device then a full listing of
configured devices is displayed.  This requires sysctl access which
genkey()'s use of capability mode was blocking permission to access.
This leads to both confusing console spam but also incorrectly returning
an error status even if no other had been encountered.

	dumpon: Sysctl get 'kern.shutdown.dumpdevname': Operation not permitted

Fix this by generating the key in a child process.

Reviewed by:	markj
Sponsored by:	Dell EMC
Differential Revision: https://reviews.freebsd.org/D31266
---
 sbin/dumpon/dumpon.c | 47 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/sbin/dumpon/dumpon.c b/sbin/dumpon/dumpon.c
index 183ce5f08cb3..ef1eb3defc98 100644
--- a/sbin/dumpon/dumpon.c
+++ b/sbin/dumpon/dumpon.c
@@ -48,6 +48,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/disk.h>
 #include <sys/socket.h>
 #include <sys/sysctl.h>
+#include <sys/wait.h>
 
 #include <assert.h>
 #include <capsicum_helpers.h>
@@ -210,7 +211,7 @@ check_size(int fd, const char *fn)
 
 #ifdef HAVE_CRYPTO
 static void
-genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
+_genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
 {
 	FILE *fp;
 	RSA *pubkey;
@@ -305,6 +306,50 @@ genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
 	}
 	RSA_free(pubkey);
 }
+
+/*
+ * Run genkey() in a child so it can use capability mode without affecting
+ * the rest of the runtime.
+ */
+static void
+genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
+{
+	pid_t pid;
+	int error, filedes[2], status;
+	ssize_t bytes;
+
+	if (pipe2(filedes, O_CLOEXEC) != 0)
+		err(1, "pipe");
+	pid = fork();
+	switch (pid) {
+	case -1:
+		err(1, "fork");
+		break;
+	case 0:
+		close(filedes[0]);
+		_genkey(pubkeyfile, kdap);
+		/* Write the new kdap back to the parent. */
+		bytes = write(filedes[1], kdap, sizeof(*kdap));
+		if (bytes != sizeof(*kdap))
+			err(1, "genkey pipe write");
+		_exit(0);
+	}
+	close(filedes[1]);
+	/* Read in the child's genkey() result into kdap. */
+	bytes = read(filedes[0], kdap, sizeof(*kdap));
+	if (bytes != sizeof(*kdap))
+		errx(1, "genkey pipe read");
+	error = waitpid(pid, &status, WEXITED);
+	if (error == -1)
+		err(1, "waitpid");
+	if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
+		errx(1, "genkey child exited with status %d",
+		    WEXITSTATUS(status));
+	else if (WIFSIGNALED(status))
+		errx(1, "genkey child exited with signal %d",
+		    WTERMSIG(status));
+	close(filedes[0]);
+}
 #endif
 
 static void