Read the lease file into a statically sized buffer and pass it over to

the engine process for parsing instead of passing an fd.
Let's us tighten the engine's pledge back down to "stdio".

diff --git a/sbin/dhcpleased/dhcpleased.c b/sbin/dhcpleased/dhcpleased.c
index 38a95d2..ae0efe7 100644 (file)
--- a/sbin/dhcpleased/dhcpleased.c
+++ b/sbin/dhcpleased/dhcpleased.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dhcpleased.c,v 1.1 2021/02/26 16:16:37 florian Exp $  */
+/*     $OpenBSD: dhcpleased.c,v 1.2 2021/02/27 10:07:41 florian Exp $  */
 
 /*
  * Copyright (c) 2017, 2021 Florian Obser <florian@openbsd.org>
@@ -78,7 +78,7 @@ void   configure_interface(struct imsg_configure_interface *);
 void    deconfigure_interface(struct imsg_configure_interface *);
 void    propose_rdns(struct imsg_propose_rdns *);
 void    configure_gateway(struct imsg_configure_interface *, uint8_t);
-int     open_lease_file(int);
+void    read_lease_file(struct imsg_ifinfo *);
 
 static int     main_imsg_send_ipc_sockets(struct imsgbuf *, struct imsgbuf *);
 int            main_imsg_compose_frontend(int, int, void *, uint16_t);
@@ -426,9 +426,9 @@ main_dispatch_frontend(int fd, short event, void *bula)
                                fatalx("%s: IMSG_UPDATE_IF wrong length: %lu",
                                    __func__, IMSG_DATA_SIZE(imsg));
                        memcpy(&imsg_ifinfo, imsg.data, sizeof(imsg_ifinfo));
-                       main_imsg_compose_engine(IMSG_UPDATE_IF,
-                           open_lease_file(imsg_ifinfo.if_index), &imsg_ifinfo,
-                           sizeof(imsg_ifinfo));
+                       read_lease_file(&imsg_ifinfo);
+                       main_imsg_compose_engine(IMSG_UPDATE_IF, -1,
+                           &imsg_ifinfo, sizeof(imsg_ifinfo));
                        break;
                default:
                        log_debug("%s: error handling imsg %d", __func__,
@@ -955,16 +955,19 @@ propose_rdns(struct imsg_propose_rdns *rdns)
                log_warn("failed to send route message");
 }
 
-int
-open_lease_file(int if_index)
+void
+read_lease_file(struct imsg_ifinfo *imsg_ifinfo)
 {
-       int      len;
+       int      len, fd;
        char     if_name[IF_NAMESIZE];
        char     lease_file_buf[sizeof(LEASE_PATH) + IF_NAMESIZE];
 
-       if (if_indextoname(if_index, if_name) == 0) {
-               log_warnx("%s: cannot find interface %d", __func__, if_index);
-               return -1;
+       memset(imsg_ifinfo->lease, 0, sizeof(imsg_ifinfo->lease));
+
+       if (if_indextoname(imsg_ifinfo->if_index, if_name) == 0) {
+               log_warnx("%s: cannot find interface %d", __func__,
+                   imsg_ifinfo->if_index);
+               return;
        }
 
        len = snprintf(lease_file_buf, sizeof(lease_file_buf), "%s%s",
@@ -972,8 +975,13 @@ open_lease_file(int if_index)
        if ( len == -1 || (size_t) len >= sizeof(lease_file_buf)) {
                log_warnx("%s: failed to encode lease path for %s", __func__,
                    if_name);
-               return -1;
+               return;
        }
 
-       return (open(lease_file_buf, O_RDONLY));
+       if ((fd = open(lease_file_buf, O_RDONLY)) == -1)
+               return;
+
+       /* no need for error handling, we'll just do a DHCP discover */
+       read(fd, imsg_ifinfo->lease, sizeof(imsg_ifinfo->lease) - 1);
+       close(fd);
 }

diff --git a/sbin/dhcpleased/dhcpleased.h b/sbin/dhcpleased/dhcpleased.h
index ff17968..a81dd18 100644 (file)
--- a/sbin/dhcpleased/dhcpleased.h
+++ b/sbin/dhcpleased/dhcpleased.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dhcpleased.h,v 1.1 2021/02/26 16:16:37 florian Exp $  */
+/*     $OpenBSD: dhcpleased.h,v 1.2 2021/02/27 10:07:41 florian Exp $  */
 
 /*
  * Copyright (c) 2017, 2021 Florian Obser <florian@openbsd.org>
@@ -222,6 +222,7 @@ struct imsg_ifinfo {
        int                     running;
        int                     link_state;
        struct ether_addr       hw_address;
+       char                    lease[LEASE_SIZE];
 };
 
 struct imsg_propose_rdns {

diff --git a/sbin/dhcpleased/engine.c b/sbin/dhcpleased/engine.c
index dace5fc..092aa45 100644 (file)
--- a/sbin/dhcpleased/engine.c
+++ b/sbin/dhcpleased/engine.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: engine.c,v 1.1 2021/02/26 16:16:37 florian Exp $      */
+/*     $OpenBSD: engine.c,v 1.2 2021/02/27 10:07:41 florian Exp $      */
 
 /*
  * Copyright (c) 2017, 2021 Florian Obser <florian@openbsd.org>
@@ -110,7 +110,7 @@ void                         engine_dispatch_main(int, short, void *);
 void                    send_interface_info(struct dhcpleased_iface *, pid_t);
 void                    engine_showinfo_ctl(struct imsg *, uint32_t);
 #endif /* SMALL */
-void                    engine_update_iface(struct imsg_ifinfo *, int);
+void                    engine_update_iface(struct imsg_ifinfo *);
 struct dhcpleased_iface        *get_dhcpleased_iface_by_id(uint32_t);
 void                    remove_dhcpleased_iface(uint32_t);
 void                    parse_dhcp(struct dhcpleased_iface *,
@@ -124,7 +124,8 @@ void                         send_configure_interface(struct dhcpleased_iface *);
 void                    send_rdns_proposal(struct dhcpleased_iface *);
 void                    send_deconfigure_interface(struct dhcpleased_iface *);
 void                    send_rdns_withdraw(struct dhcpleased_iface *);
-void                    parse_lease(int, struct dhcpleased_iface *);
+void                    parse_lease(struct dhcpleased_iface *,
+                            struct imsg_ifinfo *);
 int                     engine_imsg_compose_main(int, pid_t, void *, uint16_t);
 
 static struct imsgev   *iev_frontend;
@@ -406,13 +407,17 @@ engine_dispatch_main(int fd, short event, void *bula)
                        iev_frontend->events, iev_frontend->handler,
                            iev_frontend);
                        event_add(&iev_frontend->ev, NULL);
+
+                       if (pledge("stdio", NULL) == -1)
+                               fatal("pledge");
+
                        break;
                case IMSG_UPDATE_IF:
                        if (IMSG_DATA_SIZE(imsg) != sizeof(imsg_ifinfo))
                                fatalx("%s: IMSG_UPDATE_IF wrong length: %lu",
                                    __func__, IMSG_DATA_SIZE(imsg));
                        memcpy(&imsg_ifinfo, imsg.data, sizeof(imsg_ifinfo));
-                       engine_update_iface(&imsg_ifinfo, imsg.fd);
+                       engine_update_iface(&imsg_ifinfo);
                        break;
                default:
                        log_debug("%s: unexpected imsg %d", __func__,
@@ -481,7 +486,7 @@ engine_showinfo_ctl(struct imsg *imsg, uint32_t if_index)
 }
 #endif /* SMALL */
 void
-engine_update_iface(struct imsg_ifinfo *imsg_ifinfo, int fd)
+engine_update_iface(struct imsg_ifinfo *imsg_ifinfo)
 {
        struct dhcpleased_iface *iface;
        int                      need_refresh = 0;
@@ -502,14 +507,9 @@ engine_update_iface(struct imsg_ifinfo *imsg_ifinfo, int fd)
                memcpy(&iface->hw_address, &imsg_ifinfo->hw_address,
                    sizeof(struct ether_addr));
                LIST_INSERT_HEAD(&dhcpleased_interfaces, iface, entries);
-
-               if (fd != -1)
-                       parse_lease(fd, iface);
+               parse_lease(iface, imsg_ifinfo);
                need_refresh = 1;
        } else {
-               if (fd != -1)
-                       close(fd);
-
                if (memcmp(&iface->hw_address, &imsg_ifinfo->hw_address,
                    sizeof(struct ether_addr)) != 0) {
                        memcpy(&iface->hw_address, &imsg_ifinfo->hw_address,
@@ -1300,28 +1300,23 @@ send_rdns_withdraw(struct dhcpleased_iface *iface)
 }
 
 void
-parse_lease(int fd, struct dhcpleased_iface *iface)
+parse_lease(struct dhcpleased_iface *iface, struct imsg_ifinfo *imsg_ifinfo)
 {
-       ssize_t  len;
-       char     lease_buf[LEASE_SIZE], *p, *p1;
+       char    *p, *p1;
 
-       memset(lease_buf, 0, sizeof(lease_buf));
+       /* make sure this is a string */
+       imsg_ifinfo->lease[sizeof(imsg_ifinfo->lease) - 1] = '\0';
 
-       len = read(fd, lease_buf, sizeof(lease_buf) - 1);
+       iface->requested_ip.s_addr = INADDR_ANY;
 
-       if (len <= 0)
-               goto out;
-
-       if ((p = strstr(lease_buf, LEASE_PREFIX)) == NULL)
-               goto out;
+       if ((p = strstr(imsg_ifinfo->lease, LEASE_PREFIX)) == NULL)
+               return;
 
        p += sizeof(LEASE_PREFIX) - 1;
        if ((p1 = strchr(p, '\n')) == NULL)
-               goto out;
+               return;
        *p1 = '\0';
 
        if (inet_pton(AF_INET, p, &iface->requested_ip) != 1)
                iface->requested_ip.s_addr = INADDR_ANY;
- out:
-       close(fd);
 }