From: Roy Marples <roy@marples.name>
Date: Tue, 14 Jul 2026 14:01:47 +0000 (+0100)
Subject: Fix the control socket for dhcpcd-ui
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=90b239e1e847b71e5fca84d805edbcebcfa4a3ac;p=thirdparty%2Fdhcpcd.git

Fix the control socket for dhcpcd-ui

Add --isprivileged to return either true or false so the
caller can work this out as we now just have the one socket.
Bump version for this.
---

diff --git a/src/control.c b/src/control.c
index 8afc4f62..473d6f37 100644
--- a/src/control.c
+++ b/src/control.c
@@ -133,7 +133,7 @@ getpeereid(int fd, uid_t *uid, gid_t *gid)
 }
 #endif
 
-static int
+static ssize_t
 control_handle_read(struct fd_list *fd)
 {
 	uid_t uid;
@@ -153,7 +153,7 @@ control_handle_read(struct fd_list *fd)
 	if (bytes == -1)
 		logerr(__func__);
 	if (bytes == -1 || bytes == 0)
-		return (int)bytes;
+		return bytes;
 
 	if (getpeereid(fd->fd, &uid, &gid) == -1) {
 		logerr("%s: getpeereid", __func__);
@@ -177,12 +177,14 @@ control_handle_read(struct fd_list *fd)
 		fd->flags |= FD_SENDLEN;
 		perr = ps_ctl_handleargs(fd, buf, (size_t)bytes);
 		fd->flags &= ~FD_SENDLEN;
+		if (!(fd->flags & FD_LISTEN))
+			fd->flags |= FD_COMMAND;
 		if (perr == -1) {
 			logerr(__func__);
 			return 0;
 		}
 		iov[0].iov_len = (size_t)bytes;
-		if (perr == 1 && ps_ctl_sendmsg(fd, &msg) == -1) {
+		if (perr == 0 && ps_ctl_sendmsg(fd, &msg) == -1) {
 			logerr(__func__);
 			return -1;
 		}
@@ -202,28 +204,30 @@ control_handle_read(struct fd_list *fd)
 	return control_recvmsg(fd, &msg, (size_t)bytes);
 }
 
-static int
+static ssize_t
 control_handle_write(struct fd_list *fd)
 {
 	struct iovec iov[2];
-	int iov_len;
+	struct msghdr msg = { .msg_iov = iov };
 	struct fd_data *data;
+	ssize_t len;
 
 	data = TAILQ_FIRST(&fd->queue);
 
 	if (data->data_flags & FD_SENDLEN) {
 		iov[0].iov_base = &data->data_len;
-		iov[0].iov_len = sizeof(size_t);
+		iov[0].iov_len = sizeof(data->data_len);
 		iov[1].iov_base = data->data;
 		iov[1].iov_len = data->data_len;
-		iov_len = 2;
+		msg.msg_iovlen = 2;
 	} else {
 		iov[0].iov_base = data->data;
 		iov[0].iov_len = data->data_len;
-		iov_len = 1;
+		msg.msg_iovlen = 1;
 	}
 
-	if (writev(fd->fd, iov, iov_len) == -1) {
+	len = sendmsg(fd->fd, &msg, 0);
+	if (len == -1) {
 		if (errno != EPIPE && errno != ENOTCONN) {
 			// We don't get ELE_HANGUP for some reason
 			logerr("%s: write", __func__);
@@ -242,20 +246,23 @@ control_handle_write(struct fd_list *fd)
 #endif
 
 	if (TAILQ_FIRST(&fd->queue) != NULL)
-		return 0;
+		return len;
 
 	/* Done sending data, stop watching write to fd */
 	if (eloop_event_add(fd->ctx->eloop, fd->fd, ELE_READ,
 		control_handle_data, fd) == -1)
 		logerr("%s: eloop_event_add", __func__);
-	return 0;
+	return len;
 }
 
 static void
 control_handle_data(void *arg, unsigned short events)
 {
 	struct fd_list *fd = arg;
-	int err;
+	ssize_t err;
+
+	if (events & ELE_HANGUP)
+		goto hangup;
 
 	if (!(events & (ELE_READ | ELE_WRITE | ELE_HANGUP)))
 		logerrx("%s: unexpected event 0x%04x", __func__, events);
@@ -270,8 +277,6 @@ control_handle_data(void *arg, unsigned short events)
 		if ((err == -1 && errno != EPERM) || err == 0)
 			goto hangup;
 	}
-	if (events & ELE_HANGUP)
-		goto hangup;
 
 	return;
 
@@ -339,6 +344,8 @@ control_recvmsg(struct fd_list *fd, struct msghdr *msg, size_t len)
 			if (errno != EINTR && errno != EAGAIN && errno != EPERM)
 				return -1;
 		}
+		if (!(fd->flags & FD_LISTEN))
+			fd->flags |= FD_COMMAND;
 	}
 
 	return 1;
@@ -412,7 +419,6 @@ control_handle1(struct dhcpcd_ctx *ctx, int lfd, unsigned int fd_flags,
 	else
 #endif
 		fd_flags |= FD_SENDLEN;
-
 	l = control_new(ctx, fd, fd_flags);
 	if (l == NULL)
 		goto error;
@@ -618,7 +624,7 @@ control_send(struct dhcpcd_ctx *ctx, int argc, char *const *argv)
 }
 
 int
-control_queue(struct fd_list *fd, void *data, size_t data_len)
+control_queue(struct fd_list *fd, const void *data, size_t data_len)
 {
 	struct fd_data *d;
 	unsigned short events;
diff --git a/src/control.h b/src/control.h
index 85086025..fd8d64b7 100644
--- a/src/control.h
+++ b/src/control.h
@@ -66,8 +66,9 @@ struct fd_list {
 TAILQ_HEAD(fd_list_head, fd_list);
 
 #define FD_LISTEN  0x01U
-#define FD_PRIV	   0x02U
-#define FD_SENDLEN 0x04U
+#define FD_COMMAND 0x02U
+#define FD_PRIV	   0x04U
+#define FD_SENDLEN 0x08U
 
 int control_start(struct dhcpcd_ctx *, const char *, sa_family_t);
 int control_stop(struct dhcpcd_ctx *);
@@ -77,7 +78,7 @@ struct fd_list *control_find(struct dhcpcd_ctx *, int);
 struct fd_list *control_new(struct dhcpcd_ctx *, int, unsigned int);
 void control_free(struct fd_list *);
 void control_delete(struct fd_list *);
-int control_queue(struct fd_list *, void *, size_t);
+int control_queue(struct fd_list *, const void *, size_t);
 int control_recvmsg(struct fd_list *, struct msghdr *, size_t);
 int control_user_ispriv(struct dhcpcd_ctx *ctx, uid_t uid, gid_t gid);
 #endif
diff --git a/src/defs.h b/src/defs.h
index d21a8fae..61f80579 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -29,7 +29,7 @@
 #define DEFS_H
 
 #define PACKAGE "dhcpcd"
-#define VERSION "10.3.2"
+#define VERSION "10.5.0"
 
 #ifndef PRIVSEP_USER
 #define PRIVSEP_USER "_" PACKAGE
diff --git a/src/dhcpcd.c b/src/dhcpcd.c
index f45c4f38..d3b2bbea 100644
--- a/src/dhcpcd.c
+++ b/src/dhcpcd.c
@@ -1587,24 +1587,6 @@ dhcpcd_handleargs(struct dhcpcd_ctx *ctx, struct fd_list *fd, int argc,
 	size_t len, l, nifaces;
 	char *tmp, *p;
 
-	/* Special commands for our control socket
-	 * as the other end should be blocking until it gets the
-	 * expected reply we should be safely able just to change the
-	 * write callback on the fd */
-	/* Make any change here in privsep-control.c as well. */
-	if (strcmp(*argv, "--version") == 0) {
-		return control_queue(fd, UNCONST(VERSION), strlen(VERSION) + 1);
-	} else if (strcmp(*argv, "--getconfigfile") == 0) {
-		return control_queue(fd, UNCONST(fd->ctx->cffile),
-		    strlen(fd->ctx->cffile) + 1);
-	} else if (strcmp(*argv, "--getinterfaces") == 0) {
-		oifind = argc = 0;
-		goto dumplease;
-	} else if (strcmp(*argv, "--listen") == 0) {
-		fd->flags |= FD_LISTEN;
-		return 0;
-	}
-
 	/* Log the command */
 	len = 1;
 	for (opt = 0; opt < argc; opt++)
@@ -1624,6 +1606,27 @@ dhcpcd_handleargs(struct dhcpcd_ctx *ctx, struct fd_list *fd, int argc,
 	loginfox("control command: %s", tmp);
 	free(tmp);
 
+	/* Special commands for our control socket
+	 * as the other end should be blocking until it gets the
+	 * expected reply we should be safely able just to change the
+	 * write callback on the fd */
+	/* Make any change here in privsep-control.c as well. */
+	if (strcmp(*argv, "--version") == 0) {
+		return control_queue(fd, VERSION, strlen(VERSION) + 1);
+	} else if (strcmp(*argv, "--getconfigfile") == 0) {
+		return control_queue(fd, fd->ctx->cffile,
+		    strlen(fd->ctx->cffile) + 1);
+	} else if (strcmp(*argv, "--getinterfaces") == 0) {
+		oifind = argc = 0;
+		goto dumplease;
+	} else if (strcmp(*argv, "--isprivileged") == 0) {
+		const char *ret = fd->flags & FD_PRIV ? "true" : "false";
+		return control_queue(fd, ret, strlen(ret) + 1);
+	} else if (strcmp(*argv, "--listen") == 0) {
+		fd->flags |= FD_LISTEN;
+		return 0;
+	}
+
 	optind = 0;
 	oi = 0;
 	opts = 0;
@@ -1682,8 +1685,10 @@ dhcpcd_handleargs(struct dhcpcd_ctx *ctx, struct fd_list *fd, int argc,
 				nifaces += (size_t)opt;
 			}
 		}
-		if (write(fd->fd, &nifaces, sizeof(nifaces)) != sizeof(nifaces))
+		fd->flags &= ~FD_SENDLEN;
+		if (control_queue(fd, &nifaces, sizeof(nifaces)) == -1)
 			goto dumperr;
+		fd->flags |= FD_SENDLEN;
 		TAILQ_FOREACH(ifp, ctx->ifaces, next) {
 			if (!ifp->active)
 				continue;
diff --git a/src/privsep-control.c b/src/privsep-control.c
index cb27de1b..468270b8 100644
--- a/src/privsep-control.c
+++ b/src/privsep-control.c
@@ -83,19 +83,26 @@ ps_ctl_recvmsg(void *arg, unsigned short events)
 ssize_t
 ps_ctl_handleargs(struct fd_list *fd, char *data, size_t len)
 {
+	int err;
+
 	/* Make any change here in dhcpcd.c as well. */
 	if (strncmp(data, "--version", MIN(strlen("--version"), len)) == 0) {
-		return control_queue(fd, UNCONST(VERSION), strlen(VERSION) + 1);
+		err = control_queue(fd, UNCONST(VERSION), strlen(VERSION) + 1);
+		return err == -1 ? -1 : 1;
 	} else if (strncmp(data, "--getconfigfile",
 		       MIN(strlen("--getconfigfile"), len)) == 0) {
-		return control_queue(fd, UNCONST(fd->ctx->cffile),
+		err = control_queue(fd, UNCONST(fd->ctx->cffile),
 		    strlen(fd->ctx->cffile) + 1);
+		return err == -1 ? -1 : 1;
+	} else if (strcmp(data, "--isprivileged") == 0) {
+		const char *ret = fd->flags & FD_PRIV ? "true" : "false";
+		return control_queue(fd, ret, strlen(ret) + 1);
 	} else if (strncmp(data, "--listen", MIN(strlen("--listen"), len)) ==
 	    0) {
 		fd->flags |= FD_LISTEN;
-		return 0;
+		return 1;
 	}
-	return 1;
+	return 0;
 }
 
 static ssize_t
@@ -141,10 +148,19 @@ ps_ctl_dodispatch(void *arg, unsigned short events)
 static void
 ps_ctl_recv(void *arg, unsigned short events)
 {
-	char buf[BUFSIZ];
 	struct dhcpcd_ctx *ctx = arg;
-	ssize_t len;
-	struct fd_list *fd;
+	char buf[BUFSIZ];
+	struct iovec iov[] = { {
+	    .iov_base = buf,
+	    .iov_len = sizeof(buf),
+	} };
+	struct msghdr msg = {
+		.msg_iov = iov,
+		.msg_iovlen = __arraycount(iov),
+	};
+	ssize_t msglen;
+	int fd;
+	struct fd_list *fdl;
 
 	if (events & ELE_HANGUP) {
 	hangup:
@@ -152,22 +168,23 @@ ps_ctl_recv(void *arg, unsigned short events)
 		return;
 	}
 
-	if (!(events & ELE_READ)) {
+	if (!(events & ELE_READ))
 		logerrx("%s: unexpected event 0x%04x", __func__, events);
-		return;
-	}
 
-	len = read(ctx->ps_ctl->psp_work_fd, buf, sizeof(buf));
-	if (len == -1) {
-		logerr("%s: read", __func__);
-		return;
-	} else if (len == 0)
+	fd = ctx->ps_ctl->psp_work_fd;
+	msglen = recvmsg(fd, &msg, 0);
+	if (msglen == 0)
 		goto hangup;
+	if (msglen == -1) {
+		logerr("%s: read", __func__);
+		eloop_exit(ctx->eloop, EXIT_FAILURE);
+	}
 
-	TAILQ_FOREACH(fd, &ctx->control_fds, next) {
-		if (fd->flags & FD_LISTEN)
+	/* Send to our command controls */
+	TAILQ_FOREACH(fdl, &ctx->control_fds, next) {
+		if (!(fdl->flags & FD_COMMAND))
 			continue;
-		if (control_queue(fd, buf, (size_t)len) == -1)
+		if (control_queue(fdl, buf, (size_t)msglen) == -1)
 			logerr("%s: control_queue", __func__);
 	}
 }
@@ -176,9 +193,10 @@ static void
 ps_ctl_listen(void *arg, unsigned short events)
 {
 	struct dhcpcd_ctx *ctx = arg;
-	char buf[BUFSIZ];
 	ssize_t len;
-	struct fd_list *fd;
+	size_t msglen;
+	int fd;
+	struct fd_list *fdl;
 
 	if (events & ELE_HANGUP) {
 	hangup:
@@ -189,22 +207,40 @@ ps_ctl_listen(void *arg, unsigned short events)
 	if (!(events & ELE_READ))
 		logerrx("%s: unexpected event 0x%04x", __func__, events);
 
-	len = read(ctx->ps_control->fd, buf, sizeof(buf));
-	if (len == -1) {
-		logerr("%s: read", __func__);
-		eloop_exit(ctx->eloop, EXIT_FAILURE);
-		return;
+	fd = ctx->ps_control->fd;
+	len = read(fd, &msglen, sizeof(msglen));
+	if (len == 0)
+		goto hangup;
+	if (len != sizeof(msglen)) {
+		logerr("%s: read len", __func__);
+		goto err;
 	}
+
+	if (ps_bufalloc(ctx, msglen) == -1) {
+		logerr("%s: realloc", __func__);
+		goto err;
+	}
+
+	len = read(fd, ctx->ps_buf, msglen);
 	if (len == 0)
 		goto hangup;
+	if ((size_t)len != msglen) {
+		logerr("%s: read", __func__);
+		goto err;
+	}
 
 	/* Send to our listeners */
-	TAILQ_FOREACH(fd, &ctx->control_fds, next) {
-		if (fd == ctx->ps_control || !(fd->flags & FD_LISTEN))
+	TAILQ_FOREACH(fdl, &ctx->control_fds, next) {
+		if (!(fdl->flags & FD_LISTEN))
 			continue;
-		if (control_queue(fd, buf, (size_t)len) == -1)
+		if (control_queue(fdl, ctx->ps_buf, msglen) == -1)
 			logerr("%s: control_queue", __func__);
 	}
+
+	return;
+
+err:
+	eloop_exit(ctx->eloop, EXIT_FAILURE);
 }
 
 pid_t
@@ -220,8 +256,10 @@ ps_ctl_start(struct dhcpcd_ctx *ctx)
 
 	if_closesockets(ctx);
 
-	if (xsocketpair(AF_UNIX, SOCK_STREAM | SOCK_CXNB, 0, work_fd) == -1 ||
-	    xsocketpair(AF_UNIX, SOCK_STREAM | SOCK_CXNB, 0, listen_fd) == -1)
+	if (xsocketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, work_fd) ==
+		-1 ||
+	    xsocketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, listen_fd) ==
+		-1)
 		return -1;
 #ifdef PRIVSEP_RIGHTS
 	if (ps_rights_limit_fdpair(work_fd) == -1 ||
@@ -255,7 +293,7 @@ ps_ctl_start(struct dhcpcd_ctx *ctx)
 		ctx) == -1)
 		return -1;
 
-	ctx->ps_control = control_new(ctx, listen_fd[1], FD_LISTEN);
+	ctx->ps_control = control_new(ctx, listen_fd[1], 0);
 	if (ctx->ps_control == NULL)
 		return -1;
 	if (eloop_event_add(ctx->eloop, ctx->ps_control->fd, ELE_READ,