git: 372557d8c3d3 - main - dumpon: Fix -v causing error when configuring an encrypted dump

[Bryan Drewery]

The branch main has been updated by bdrewery:

URL: https://cgit.FreeBSD.org/src/commit/?id=372557d8c3d37dd0c1d9be56513a436393963848

commit 372557d8c3d37dd0c1d9be56513a436393963848
Author:     Bryan Drewery <bdrewery at FreeBSD.org>
AuthorDate: 2021-07-22 00:37:03 +0000
Commit:     Bryan Drewery <bdrewery at FreeBSD.org>
CommitDate: 2021-07-26 20:08:59 +0000

    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