From: Roy Marples <roy@marples.name>
Date: Tue, 16 May 2023 16:16:26 +0000 (+0100)
Subject: privsep: Allow zero length messages through
X-Git-Tag: v10.0.2~23
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8b29c0ddf026c1c5647c3b8c6cfe21699c4056ae;p=thirdparty%2Fdhcpcd.git

privsep: Allow zero length messages through

They should be handled gracefully without privsep anyway.
Fix for #179.
---

diff --git a/src/privsep-inet.c b/src/privsep-inet.c
index ec239e86..e59c3353 100644
--- a/src/privsep-inet.c
+++ b/src/privsep-inet.c
@@ -53,7 +53,7 @@ ps_inet_recvbootp(void *arg, unsigned short events)
 {
 	struct dhcpcd_ctx *ctx = arg;
 
-	if (ps_recvmsg(ctx, ctx->udp_rfd, events,
+	if (ps_recvmsg(ctx->udp_rfd, events,
 	    PS_BOOTP, ctx->ps_inet->psp_fd) == -1)
 		logerr(__func__);
 }
@@ -68,13 +68,13 @@ ps_inet_recvra(void *arg, unsigned short events)
 	struct rs_state *state = RS_STATE(ifp);
 	struct dhcpcd_ctx *ctx = ifp->ctx;
 
-	if (ps_recvmsg(ctx, state->nd_fd, events,
+	if (ps_recvmsg(state->nd_fd, events,
 	    PS_ND, ctx->ps_inet->psp_fd) == -1)
 		logerr(__func__);
 #else
 	struct dhcpcd_ctx *ctx = arg;
 
-	if (ps_recvmsg(ctx, ctx->nd_fd, events,
+	if (ps_recvmsg(ctx->nd_fd, events,
 	    PS_ND, ctx->ps_inet->psp_fd) == -1)
 		logerr(__func__);
 #endif
@@ -87,7 +87,7 @@ ps_inet_recvdhcp6(void *arg, unsigned short events)
 {
 	struct dhcpcd_ctx *ctx = arg;
 
-	if (ps_recvmsg(ctx, ctx->dhcp6_rfd, events,
+	if (ps_recvmsg(ctx->dhcp6_rfd, events,
 	    PS_DHCP6, ctx->ps_inet->psp_fd) == -1)
 		logerr(__func__);
 }
@@ -387,7 +387,7 @@ ps_inet_recvinbootp(void *arg, unsigned short events)
 {
 	struct ps_process *psp = arg;
 
-	if (ps_recvmsg(psp->psp_ctx, psp->psp_work_fd, events,
+	if (ps_recvmsg(psp->psp_work_fd, events,
 	    PS_BOOTP, psp->psp_ctx->ps_data_fd) == -1)
 		logerr(__func__);
 }
@@ -430,7 +430,7 @@ ps_inet_recvin6nd(void *arg)
 {
 	struct ps_process *psp = arg;
 
-	if (ps_recvmsg(psp->psp_ctx, psp->psp_work_fd,
+	if (ps_recvmsg(psp->psp_work_fd,
 	    PS_ND, psp->psp_ctx->ps_data_fd) == -1)
 		logerr(__func__);
 }
@@ -470,7 +470,7 @@ ps_inet_recvin6dhcp6(void *arg, unsigned short events)
 {
 	struct ps_process *psp = arg;
 
-	if (ps_recvmsg(psp->psp_ctx, psp->psp_work_fd, events,
+	if (ps_recvmsg(psp->psp_work_fd, events,
 	    PS_DHCP6, psp->psp_ctx->ps_data_fd) == -1)
 		logerr(__func__);
 }
diff --git a/src/privsep.c b/src/privsep.c
index 765756d7..b11c0351 100644
--- a/src/privsep.c
+++ b/src/privsep.c
@@ -1069,8 +1069,7 @@ nobufs:
 }
 
 ssize_t
-ps_recvmsg(struct dhcpcd_ctx *ctx, int rfd, unsigned short events,
-    uint16_t cmd, int wfd)
+ps_recvmsg(int rfd, unsigned short events, uint16_t cmd, int wfd)
 {
 	struct sockaddr_storage ss = { .ss_family = AF_UNSPEC };
 	uint8_t controlbuf[sizeof(struct sockaddr_storage)] = { 0 };
@@ -1089,22 +1088,15 @@ ps_recvmsg(struct dhcpcd_ctx *ctx, int rfd, unsigned short events,
 		logerrx("%s: unexpected event 0x%04x", __func__, events);
 
 	len = recvmsg(rfd, &msg, 0);
-	if (len == -1)
+	if (len == -1) {
 		logerr("%s: recvmsg", __func__);
-	if (len == -1 || len == 0) {
-		if (ctx->options & DHCPCD_FORKED)
-			eloop_exit(ctx->eloop,
-			    len != -1 ? EXIT_SUCCESS : EXIT_FAILURE);
 		return len;
 	}
 
 	iov[0].iov_len = (size_t)len;
 	len = ps_sendcmdmsg(wfd, cmd, &msg);
-	if (len == -1) {
+	if (len == -1)
 		logerr("%s: ps_sendcmdmsg", __func__);
-		if (ctx->options & DHCPCD_FORKED)
-			eloop_exit(ctx->eloop, EXIT_FAILURE);
-	}
 	return len;
 }
 
diff --git a/src/privsep.h b/src/privsep.h
index a4289325..f03b2be7 100644
--- a/src/privsep.h
+++ b/src/privsep.h
@@ -211,7 +211,7 @@ ssize_t ps_sendmsg(struct dhcpcd_ctx *, int, uint16_t, unsigned long,
     const struct msghdr *);
 ssize_t ps_sendcmd(struct dhcpcd_ctx *, int, uint16_t, unsigned long,
     const void *data, size_t len);
-ssize_t ps_recvmsg(struct dhcpcd_ctx *, int, unsigned short, uint16_t, int);
+ssize_t ps_recvmsg(int, unsigned short, uint16_t, int);
 ssize_t ps_recvpsmsg(struct dhcpcd_ctx *, int, unsigned short,
     ssize_t (*callback)(void *, struct ps_msghdr *, struct msghdr *), void *);