From: Roy Marples <roy@marples.name>
Date: Fri, 6 Jan 2023 11:14:45 +0000 (+0000)
Subject: privsep: Try sending error if we cannot send the message.
X-Git-Tag: v10.0.0~15
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=96f055d2e48ce48ce828e1c4c175d05afcd1b299;p=thirdparty%2Fdhcpcd.git

privsep: Try sending error if we cannot send the message.

There is an error sending a reply from an INET6 sysctl RT dump
on FreeBSD-14 using the dhcpcd-9 branch.
It seems to be related to capsicum and doesn't happen on FreeBSD-13.
We should handle the error gracefully and allow dhcpcd to try to
contuinue regardless.
---

diff --git a/src/privsep-root.c b/src/privsep-root.c
index 0bf2345c..5fda1626 100644
--- a/src/privsep-root.c
+++ b/src/privsep-root.c
@@ -209,12 +209,26 @@ ps_root_writeerror(struct dhcpcd_ctx *ctx, ssize_t result,
 		{ .iov_base = &psr, .iov_len = sizeof(psr) },
 		{ .iov_base = data, .iov_len = len },
 	};
+	ssize_t err;
 
 #ifdef PRIVSEP_DEBUG
 	logdebugx("%s: result %zd errno %d", __func__, result, errno);
 #endif
 
-	return writev(ctx->ps_root->psp_fd, iov, __arraycount(iov));
+	err = writev(ctx->ps_root->psp_fd, iov, __arraycount(iov));
+
+	/* Error sending the message? Try sending the error of sending. */
+	if (err == -1) {
+		logerr("%s: result=%zd, data=%p, len=%zu",
+		    __func__, result, data, len);
+		psr.psr_result = err;
+		psr.psr_errno = errno;
+		iov[1].iov_base = NULL;
+		iov[1].iov_len = 0;
+		err = writev(ctx->ps_root->psp_fd, iov, __arraycount(iov));
+	}
+
+	return err;
 }
 
 static ssize_t