privsep: Allow Linux to work without needing any mounts

BUILDING.md

@@ -161,9 +161,3 @@ copied to `$(libexecdir)/dhcpcd-hooks` for use.
 The configure program attempts to find hooks for systems you have installed.
 To add more simply
 `./configure -with-hook=ntp.conf`
-
-If running privilege separation and on Linux then the `00-linux` hook is
-**mandatory**.
-If you choose not to run it, then you are responsible for setting up the
-needed mount points: `/dev`, `/proc`, `/sys`, `/run/udev`
-as well as sorting out `/dev/log` if it points to something outside of `/dev`.

configure

@@ -1766,9 +1766,6 @@ if cd hooks; then
 	done
 	cd ..
 fi
-if [ "$OS" = linux ]; then
-	HOOKS="$HOOKS${HOOKS:+ }00-linux"
-fi
 echo "HOOKSCRIPTS=	$HOOKS" >>$CONFIG_MK
 echo "EGHOOKSCRIPTS=	$EGHOOKS" >>$CONFIG_MK
 

hooks/00-linux

@@ -1,17 +0,0 @@
-# setup chroot mounts
-
-if [ "$reason" = CHROOT ] && [ -n "$chroot" ]; then
-	# Special case /dev/log
-	if [ -h /dev/log ]; then
-		devlogdir=$(dirname $(readlink /dev/log))
-	else
-		devlogdir=
-	fi
-	for d in /dev /proc /sys /run/udev $devlogdir; do
-		[ -d "$d" ] || continue
-		if ! mountpoint -q "$chroot$d"; then
-			mkdir -p "$chroot$d"
-			mount --bind $d "$chroot$d"
-		fi
-	done
-fi

src/common.c

@@ -109,28 +109,17 @@ ssize_t
 readfile(const char *file, void *data, size_t len)
 {
 	int fd;
-	struct stat st;
-	ssize_t bytes = -1;
+	ssize_t bytes;
 
 	fd = open(file, O_RDONLY);
 	if (fd == -1)
 		return -1;
-
-	if (fstat(fd, &st) != 0)
-		goto out;
-	if (!S_ISREG(st.st_mode)) {
-		errno = EINVAL;
-		goto out;
-	}
-	if ((size_t)st.st_size > len) {
-		errno = E2BIG;
-		goto out;
-	}
 	bytes = read(fd, data, len);
-
-out:
-	if (fd != -1)
-		close(fd);
+	close(fd);
+	if ((size_t)bytes == len) {
+		errno = ENOBUFS;
+		return -1;
+	}
 	return bytes;
 }
 

src/if-linux.c

@@ -149,7 +149,7 @@ static int if_addressexists(struct interface *, struct in_addr *);
 
 #define PROC_INET6	"/proc/net/if_inet6"
 #define PROC_PROMOTE	"/proc/sys/net/ipv4/conf/%s/promote_secondaries"
-#define SYS_BRIDGE	"/sys/class/net/%s/bridge"
+#define SYS_BRIDGE	"/sys/class/net/%s/bridge/bridge_id"
 #define SYS_LAYER2	"/sys/class/net/%s/device/layer2"
 #define SYS_TUNTAP	"/sys/class/net/%s/tun_flags"
 
@@ -220,53 +220,44 @@ if_machinearch(char *str, size_t len)
 }
 
 static int
-check_proc_int(const char *path)
+check_proc_int(struct dhcpcd_ctx *ctx, const char *path)
 {
-	FILE *fp;
-	int i;
+	char buf[64];
+	int error, i;
 
-	fp = fopen(path, "r");
-	if (fp == NULL)
+	if (dhcp_readfile(ctx, path, buf, sizeof(buf)) == -1)
 		return -1;
-	if (fscanf(fp, "%d", &i) != 1)
-		i = -1;
-	fclose(fp);
+	i = (int)strtoi(buf, NULL, 0, INT_MIN, INT_MAX, &error);
+	if (error != 0 && error != ENOTSUP) {
+		errno = error;
+		return -1;
+	}
 	return i;
 }
 
 static int
-check_proc_hex(const char *path, unsigned int *value)
+check_proc_uint(struct dhcpcd_ctx *ctx, const char *path, unsigned int *u)
 {
-	FILE *fp;
-	int i;
+	char buf[64];
+	int error;
 
-	fp = fopen(path, "r");
-	if (fp == NULL)
+	if (dhcp_readfile(ctx, path, buf, sizeof(buf)) == -1)
 		return -1;
-	i = fscanf(fp, "%x", value) == 1 ? 0 : -1;
-	fclose(fp);
-	return i;
+	*u = (unsigned int)strtou(buf, NULL, 0, 0, UINT_MAX, &error);
+	if (error != 0 && error != ENOTSUP) {
+		errno = error;
+		return error;
+	}
+	return 0;
 }
 
 static ssize_t
 if_writepathuint(struct dhcpcd_ctx *ctx, const char *path, unsigned int val)
 {
-	FILE *fp;
-	ssize_t r;
+	char buf[64];
 
-#ifdef PRIVSEP
-	if (ctx->options & DHCPCD_PRIVSEP)
-		return ps_root_writepathuint(ctx, path, val);
-#else
-	UNUSED(ctx);
-#endif
-
-	fp = fopen(path, "w");
-	if (fp == NULL)
-		return -1;
-	r = fprintf(fp, "%u\n", val);
-	fclose(fp);
-	return r;
+	snprintf(buf, sizeof(buf), "%u\n", val);
+	return dhcp_writefile(ctx, path, 0664, buf, sizeof(buf));
 }
 
 int
@@ -283,7 +274,7 @@ if_init(struct interface *ifp)
 	 * This matches the behaviour of BSD which makes coding dhcpcd
 	 * a little easier as there's just one behaviour. */
 	snprintf(path, sizeof(path), PROC_PROMOTE, ifp->name);
-	n = check_proc_int(path);
+	n = check_proc_int(ifp->ctx, path);
 	if (n == -1)
 		return errno == ENOENT ? 0 : -1;
 	if (n == 1)
@@ -299,7 +290,7 @@ if_conf(struct interface *ifp)
 
 	/* Some qeth setups require the use of the broadcast flag. */
 	snprintf(path, sizeof(path), SYS_LAYER2, ifp->name);
-	n = check_proc_int(path);
+	n = check_proc_int(ifp->ctx, path);
 	if (n == -1)
 		return errno == ENOENT ? 0 : -1;
 	if (n == 0)
@@ -308,34 +299,33 @@ if_conf(struct interface *ifp)
 }
 
 static bool
-if_bridge(const char *ifname)
+if_bridge(struct dhcpcd_ctx *ctx, const char *ifname)
 {
-	char path[sizeof(SYS_BRIDGE) + IF_NAMESIZE];
-	struct stat sb;
+	char path[sizeof(SYS_BRIDGE) + IF_NAMESIZE], buf[64];
 
 	snprintf(path, sizeof(path), SYS_BRIDGE, ifname);
-	if (stat(path, &sb) == 0 && S_ISDIR(sb.st_mode))
-		return true;
-	return false;
+	if (dhcp_readfile(ctx, path, buf, sizeof(buf)) == -1)
+		return false;
+	return true;
 }
 
 static bool
-if_tap(const char *ifname)
+if_tap(struct dhcpcd_ctx *ctx, const char *ifname)
 {
 	char path[sizeof(SYS_TUNTAP) + IF_NAMESIZE];
-	unsigned int n;
+	unsigned int u;
 
 	snprintf(path, sizeof(path), SYS_TUNTAP, ifname);
-	if (check_proc_hex(path, &n) == -1)
+	if (check_proc_uint(ctx, path, &u) == -1)
 		return false;
-	return n & IFF_TAP;
+	return u & IFF_TAP;
 }
 
 bool
-if_ignore(__unused struct dhcpcd_ctx *ctx, const char *ifname)
+if_ignore(struct dhcpcd_ctx *ctx, const char *ifname)
 {
 
-	if (if_tap(ifname) || if_bridge(ifname))
+	if (if_tap(ctx, ifname) || if_bridge(ctx, ifname))
 		return true;
 	return false;
 }
@@ -1866,14 +1856,19 @@ int
 if_addrflags6(const struct interface *ifp, const struct in6_addr *addr,
     __unused const char *alias)
 {
-	FILE *fp;
+	char buf[PS_BUFLEN], *bp = buf, *line;
+	ssize_t buflen;
 	char *p, ifaddress[33], address[33], name[IF_NAMESIZE + 1];
 	unsigned int ifindex;
 	int prefix, scope, flags, i;
 
-	fp = fopen(PROC_INET6, "r");
-	if (fp == NULL)
+	buflen = dhcp_readfile(ifp->ctx, PROC_INET6, buf, sizeof(buf));
+	if (buflen == -1)
 		return -1;
+	if ((size_t)buflen == sizeof(buf)) {
+		errno = ENOBUFS;
+		return -1;
+	}
 
 	p = ifaddress;
 	for (i = 0; i < (int)sizeof(addr->s6_addr); i++) {
@@ -1881,23 +1876,20 @@ if_addrflags6(const struct interface *ifp, const struct in6_addr *addr,
 	}
 	*p = '\0';
 
-	while (fscanf(fp, "%32[a-f0-9] %x %x %x %x %"TOSTRING(IF_NAMESIZE)"s\n",
-	    address, &ifindex, &prefix, &scope, &flags, name) == 6)
-	{
-		if (strlen(address) != 32) {
-			fclose(fp);
+	while ((line = get_line(&bp, &buflen)) != NULL) {
+		if (sscanf(line,
+		    "%32[a-f0-9] %x %x %x %x %"TOSTRING(IF_NAMESIZE)"s\n",
+		    address, &ifindex, &prefix, &scope, &flags, name) != 6 ||
+		    strlen(address) != 32)
+		{
 			errno = EINVAL;
 			return -1;
 		}
 		if (strcmp(name, ifp->name) == 0 &&
 		    strcmp(ifaddress, address) == 0)
-		{
-			fclose(fp);
 			return flags;
-		}
 	}
 
-	fclose(fp);
 	errno = ESRCH;
 	return -1;
 }
@@ -1972,11 +1964,12 @@ static const char *p_neigh = "/proc/sys/net/ipv6/neigh";
 void
 if_setup_inet6(const struct interface *ifp)
 {
+	struct dhcpcd_ctx *ctx = ifp->ctx;
 	int ra;
 	char path[256];
 
 	/* The kernel cannot make stable private addresses. */
-	if (if_disable_autolinklocal(ifp->ctx, ifp->index) == -1)
+	if (if_disable_autolinklocal(ctx, ifp->index) == -1 && errno != ENODEV)
 		logdebug("%s: if_disable_autolinklocal", ifp->name);
 
 	/*
@@ -1987,21 +1980,21 @@ if_setup_inet6(const struct interface *ifp)
 		return;
 
 	snprintf(path, sizeof(path), "%s/%s/autoconf", p_conf, ifp->name);
-	ra = check_proc_int(path);
+	ra = check_proc_int(ctx, path);
 	if (ra != 1 && ra != -1) {
-		if (if_writepathuint(ifp->ctx, path, 0) == -1)
+		if (if_writepathuint(ctx, path, 0) == -1)
 			logerr("%s: %s", __func__, path);
 	}
 
 	snprintf(path, sizeof(path), "%s/%s/accept_ra", p_conf, ifp->name);
-	ra = check_proc_int(path);
+	ra = check_proc_int(ctx, path);
 	if (ra == -1) {
 		/* The sysctl probably doesn't exist, but this isn't an
 		 * error as such so just log it and continue */
 		if (errno != ENOENT)
 			logerr("%s: %s", __func__, path);
 	} else if (ra != 0) {
-		if (if_writepathuint(ifp->ctx, path, 0) == -1)
+		if (if_writepathuint(ctx, path, 0) == -1)
 			logerr("%s: %s", __func__, path);
 	}
 }
@@ -2040,14 +2033,18 @@ if_applyra(const struct ra *rap)
 int
 ip6_forwarding(const char *ifname)
 {
-	char path[256];
-	int val;
+	char path[256], buf[64];
+	int error, i;
 
 	if (ifname == NULL)
 		ifname = "all";
 	snprintf(path, sizeof(path), "%s/%s/forwarding", p_conf, ifname);
-	val = check_proc_int(path);
-	return val == -1 ? 0 : val;
+	if (readfile(path, buf, sizeof(buf)) == -1)
+		return 0;
+	i = (int)strtoi(buf, NULL, 0, INT_MIN, INT_MAX, &error);
+	if (error != 0)
+		return -1;
+	return error != 0 ? 0 : i;
 }
 
 #endif /* INET6 */

src/ipv6.c

@@ -1106,6 +1106,13 @@ ipv6_anyglobal(struct interface *sifp)
 		if (ifp != sifp && !forwarding)
 			continue;
 #else
+#if defined(PRIVSEP) && defined(__linux__)
+	if (IN_PRIVSEP(sifp->ctx)) {
+		if (ifp != sifp &&
+		    ps_root_ip6forwarding(sifp->ctx, ifp->name) != 1)
+			continue;
+	} else
+#endif
 		if (ifp != sifp && ip6_forwarding(ifp->name) != 1)
 			continue;
 #endif

src/ipv6nd.c

@@ -524,11 +524,13 @@ ipv6nd_advertise(struct ipv6_addr *ia)
 
 	na->nd_na_type = ND_NEIGHBOR_ADVERT;
 	na->nd_na_flags_reserved = ND_NA_FLAG_OVERRIDE;
-#ifdef HAVE_PLEDGE
-	if (ps_root_ip6_forwarding(ctx) == 1)
-#else
-	if (ip6_forwarding(ifp->name) == 1)
+#if defined(PRIVSEP) && (defined(__linux__) || defined(HAVE_PLEDGE))
+	if (IN_PRIVSEP(ctx)) {
+		if (ps_root_ip6forwarding(ctx, ifp->name) == 1)
+			na->nd_na_flags_reserved |= ND_NA_FLAG_ROUTER;
+	} else
 #endif
+	if (ip6_forwarding(ifp->name) == 1)
 		na->nd_na_flags_reserved |= ND_NA_FLAG_ROUTER;
 	na->nd_na_target = ia->addr;
 

src/privsep-bsd.c

@@ -151,8 +151,6 @@ ps_root_os(struct ps_msghdr *psm, struct msghdr *msg)
 #ifdef HAVE_PLEDGE
 	case PS_IOCTLINDIRECT:
 		return ps_root_doindirectioctl(psm->ps_flags, data, len);
-	case PS_IP6FORWARDING:
-		return ip6_forwarding(NULL);
 #endif
 	default:
 		errno = ENOTSUP;
@@ -210,14 +208,4 @@ ps_root_indirectioctl(struct dhcpcd_ctx *ctx, unsigned long request,
 		return -1;
 	return ps_root_readerror(ctx, data, len);
 }
-
-ssize_t
-ps_root_ip6forwarding(struct dhcpcd_ctx *ctx)
-{
-
-	if (ps_sendcmd(ctx, ctx->ps_root_fd,
-	    PS_IP6FORWARDING, 0, NULL, 0) == -1)
-		return -1;
-	return ps_root_readerror(ctx, NULL, 0);
-}
 #endif

src/privsep-linux.c

@@ -64,50 +64,13 @@ out:
 	return retval;
 }
 
-static ssize_t
-ps_root_dowritepathuint(const void *data, size_t len)
-{
-	const char *path = data;
-	size_t plen;
-	unsigned int val;
-	int fd;
-	ssize_t r;
-
-	if (len < sizeof(plen)) {
-		errno = EINVAL;
-		return -1;
-	}
-
-	memcpy(&plen, path, sizeof(plen));
-	path += sizeof(plen);
-	if (sizeof(plen) + plen + sizeof(val) > len) {
-		errno = EINVAL;
-		return -1;
-	}
-
-	memcpy(&val, path + plen, sizeof(val));
-
-	fd = open(path, O_WRONLY);
-	if (fd == -1)
-		return -1;
-	r = dprintf(fd, "%u", val);
-	close(fd);
-
-	return r;
-}
-
 ssize_t
 ps_root_os(struct ps_msghdr *psm, struct msghdr *msg)
 {
-	struct iovec *iov = msg->msg_iov;
-	void *data = iov->iov_base;
-	size_t len = iov->iov_len;
 
 	switch (psm->ps_cmd) {
 	case PS_ROUTE:
 		return ps_root_dosendnetlink((int)psm->ps_flags, msg);
-	case PS_WRITEPATHUINT:
-		return ps_root_dowritepathuint(data, len);
 	default:
 		errno = ENOTSUP;
 		return -1;
@@ -123,28 +86,3 @@ ps_root_sendnetlink(struct dhcpcd_ctx *ctx, int protocol, struct msghdr *msg)
 		return -1;
 	return ps_root_readerror(ctx, NULL, 0);
 }
-
-ssize_t
-ps_root_writepathuint(struct dhcpcd_ctx *ctx, const char *path,
-    unsigned int val)
-{
-	char buf[PS_BUFLEN], *p = buf;
-	size_t plen = strlen(path) + 1;
-	size_t len = sizeof(plen) + plen + sizeof(val);
-
-	if (len > sizeof(buf)) {
-		errno = ENOBUFS;
-		return -1;
-	}
-
-	memcpy(p, &plen, sizeof(plen));
-	p += sizeof(plen);
-	memcpy(p, path, plen);
-	p += plen;
-	memcpy(p, &val, sizeof(val));
-
-	if (ps_sendcmd(ctx, ctx->ps_root_fd, PS_WRITEPATHUINT,
-	    0, buf, len) == -1)
-		return -1;
-	return ps_root_readerror(ctx, NULL, 0);
-}

src/privsep-root.c

@@ -295,6 +295,14 @@ ps_root_validpath(const struct dhcpcd_ctx *ctx, uint16_t cmd, const char *path)
 		return true;
 	if (strncmp(RUNDIR, path, strlen(RUNDIR)) == 0)
 		return true;
+
+#ifdef __linux__
+	if (strncmp("/proc/net/", path, strlen("/proc/net/")) == 0 ||
+	    strncmp("/proc/sys/net/", path, strlen("/proc/sys/net/")) == 0 ||
+	    strncmp("/sys/class/net/", path, strlen("/sys/class/net/")) == 0)
+		return true;
+#endif
+
 	errno = EPERM;
 	return false;
 }
@@ -310,6 +318,7 @@ ps_root_dowritefile(const struct dhcpcd_ctx *ctx,
 		errno = EINVAL;
 		return -1;
 	}
+
 	if (!ps_root_validpath(ctx, PS_WRITEFILE, file))
 		return -1;
 	nc++;
@@ -510,6 +519,11 @@ ps_root_recvmsgcb(void *arg, struct ps_msghdr *psm, struct msghdr *msg)
 		err = ps_root_dogetifaddrs(&rdata, &rlen);
 		free_rdata = true;
 		break;
+#endif
+#if defined(__linux__) || defined(HAVE_PLEDGE)
+	case PS_IP6FORWARDING:
+		 err = ip6_forwarding(data);
+		 break;
 #endif
 	default:
 		err = ps_root_os(psm, msg);
@@ -800,3 +814,15 @@ err:
 	return -1;
 }
 #endif
+
+#if defined(__linux__) || defined(HAVE_PLEDGE)
+ssize_t
+ps_root_ip6forwarding(struct dhcpcd_ctx *ctx, const char *ifname)
+{
+
+	if (ps_sendcmd(ctx, ctx->ps_root_fd,
+	    PS_IP6FORWARDING, 0, ifname, strlen(ifname) + 1) == -1)
+		return -1;
+	return ps_root_readerror(ctx, NULL, 0);
+}
+#endif

src/privsep-root.h

@@ -37,6 +37,7 @@ int ps_root_stop(struct dhcpcd_ctx *ctx);
 ssize_t ps_root_readerror(struct dhcpcd_ctx *, void *, size_t);
 ssize_t ps_root_mreaderror(struct dhcpcd_ctx *, void **, size_t *);
 ssize_t ps_root_ioctl(struct dhcpcd_ctx *, ioctl_request_t, void *, size_t);
+ssize_t ps_root_ip6forwarding(struct dhcpcd_ctx *, const char *);
 ssize_t ps_root_unlink(struct dhcpcd_ctx *, const char *);
 ssize_t ps_root_filemtime(struct dhcpcd_ctx *, const char *, time_t *);
 ssize_t ps_root_readfile(struct dhcpcd_ctx *, const char *, void *, size_t);
@@ -52,7 +53,6 @@ ssize_t ps_root_ioctllink(struct dhcpcd_ctx *, unsigned long, void *, size_t);
 ssize_t ps_root_ioctl6(struct dhcpcd_ctx *, unsigned long, void *, size_t);
 ssize_t ps_root_indirectioctl(struct dhcpcd_ctx *, unsigned long, const char *,
     void *, size_t);
-ssize_t ps_root_ip6forwarding(struct dhcpcd_ctx *);
 #endif
 #ifdef __linux__
 ssize_t ps_root_sendnetlink(struct dhcpcd_ctx *, int, struct msghdr *);

src/privsep.h

@@ -57,9 +57,6 @@
 #define	PS_IP6FORWARDING	0x0104
 #define	PS_GETIFADDRS		0x0105
 
-/* Linux commands */
-#define	PS_WRITEPATHUINT	0x0201
-
 /* Process commands */
 #define	PS_START		0x4000
 #define	PS_STOP			0x8000