From: Roy Marples <roy@marples.name>
Date: Mon, 5 Sep 2022 12:20:50 +0000 (+0100)
Subject: dhcpcd: Use eloop timeout to wait for pidfile removal
X-Git-Tag: v10.0.0~30
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3b294661fb106a6075654d6404e846df3438821e;p=thirdparty%2Fdhcpcd.git

dhcpcd: Use eloop timeout to wait for pidfile removal

As well as removing not enabled code to wait a bit before
removing the IP address when sending a DHCP RELEASE message.

This means that we no longer need to allow nanosleep in SECCOMP.

Hopefully fixes #127.
---

diff --git a/src/dhcp.c b/src/dhcp.c
index c72135ec..e24f5594 100644
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -84,11 +84,6 @@
 /* We should define a maximum for the NAK exponential backoff */
 #define NAKOFF_MAX              60
 
-/* Wait N nanoseconds between sending a RELEASE and dropping the address.
- * This gives the kernel enough time to actually send it. */
-#define RELEASE_DELAY_S		0
-#define RELEASE_DELAY_NS	10000000
-
 #ifndef IPDEFTTL
 #define IPDEFTTL 64 /* RFC1340 */
 #endif
@@ -2755,12 +2750,8 @@ dhcp_reboot(struct interface *ifp)
 void
 dhcp_drop(struct interface *ifp, const char *reason)
 {
-	struct dhcp_state *state;
-#ifdef RELEASE_SLOW
-	struct timespec ts;
-#endif
+	struct dhcp_state *state = D_STATE(ifp);
 
-	state = D_STATE(ifp);
 	/* dhcp_start may just have been called and we don't yet have a state
 	 * but we do have a timeout, so punt it. */
 	if (state == NULL || state->state == DHS_NONE) {
@@ -2794,12 +2785,6 @@ dhcp_drop(struct interface *ifp, const char *reason)
 			    ifp->name, inet_ntoa(state->lease.addr));
 			dhcp_new_xid(ifp);
 			send_message(ifp, DHCP_RELEASE, NULL);
-#ifdef RELEASE_SLOW
-			/* Give the packet a chance to go */
-			ts.tv_sec = RELEASE_DELAY_S;
-			ts.tv_nsec = RELEASE_DELAY_NS;
-			nanosleep(&ts, NULL);
-#endif
 		}
 	}
 #ifdef AUTH
@@ -2820,10 +2805,6 @@ dhcp_drop(struct interface *ifp, const char *reason)
 	dhcp_auth_reset(&state->auth);
 #endif
 
-	/* Close DHCP ports so a changed interface family is picked
-	 * up by a new BPF state. */
-	dhcp_close(ifp);
-
 	state->state = DHS_NONE;
 	free(state->offer);
 	state->offer = NULL;
@@ -2847,6 +2828,10 @@ dhcp_drop(struct interface *ifp, const char *reason)
 	state->lease.addr.s_addr = 0;
 	ifp->options->options &= ~(DHCPCD_CSR_WARNED |
 	    DHCPCD_ROUTER_HOST_ROUTE_WARNED);
+
+	/* Close DHCP ports so a changed interface family is picked
+	 * up by a new BPF state. */
+	dhcp_close(ifp);
 }
 
 static int
diff --git a/src/dhcpcd.c b/src/dhcpcd.c
index dcaba1e9..dca38086 100644
--- a/src/dhcpcd.c
+++ b/src/dhcpcd.c
@@ -1828,6 +1828,24 @@ dhcpcd_stderr_cb(void *arg, unsigned short events)
 	fprintf(stderr, "%s", log);
 }
 
+static void
+dhcpcd_pidfile_timeout(void *arg)
+{
+	struct dhcpcd_ctx *ctx = arg;
+	pid_t pid;
+
+	pid = pidfile_read(ctx->pidfile);
+
+	if(pid == -1)
+		eloop_exit(ctx->eloop, EXIT_SUCCESS);
+	else if (++ctx->duid_len >= 100) { /* overload duid_len */
+		logerrx("pid %d failed to exit", pid);
+		eloop_exit(ctx->eloop, EXIT_FAILURE);
+	} else
+		eloop_timeout_add_msec(ctx->eloop, 100,
+		    dhcpcd_pidfile_timeout, ctx);
+}
+
 int
 main(int argc, char **argv, char **envp)
 {
@@ -2164,21 +2182,12 @@ printpidfile:
 			/* We can still continue and send the command
 			 * via the control socket. */
 		} else {
-			struct timespec ts;
-
 			if (sig == SIGHUP || sig == SIGUSR1)
 				goto exit_success;
 			/* Spin until it exits */
 			loginfox("waiting for pid %d to exit", pid);
-			ts.tv_sec = 0;
-			ts.tv_nsec = 100000000; /* 10th of a second */
-			for(i = 0; i < 100; i++) {
-				nanosleep(&ts, NULL);
-				if (pidfile_read(ctx.pidfile) == -1)
-					goto exit_success;
-			}
-			logerrx("pid %d failed to exit", pid);
-			goto exit_failure;
+			dhcpcd_pidfile_timeout(&ctx);
+			goto run_loop;
 		}
 	}
 #endif
diff --git a/src/privsep-linux.c b/src/privsep-linux.c
index d4439634..c9f4ea84 100644
--- a/src/privsep-linux.c
+++ b/src/privsep-linux.c
@@ -353,9 +353,6 @@ static struct sock_filter ps_seccomp_filter[] = {
 #ifdef __NR_munmap
 	SECCOMP_ALLOW(__NR_munmap),
 #endif
-#ifdef __NR_nanosleep
-	SECCOMP_ALLOW(__NR_nanosleep),	/* XXX should use ppoll instead */
-#endif
 #ifdef __NR_newfstatat
 	SECCOMP_ALLOW(__NR_newfstatat),
 #endif