passt: Address gcc 11 warnings

A mix of unchecked return values, a missing permission mask for
open(2) with O_CREAT, and some false positives from
-Wstringop-overflow and -Wmaybe-uninitialized.

Reported-by: Martin Hauke <mardnh@gmx.de>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

7 files changed, 91 insertions, 33 deletions

diff --git a/Makefile b/Makefile
index c2077f2..6d11e22 100644
--- a/Makefile
+++ b/Makefile
@@ -15,6 +15,20 @@ CFLAGS += -DPAGE_SIZE=$(shell getconf PAGE_SIZE)
 CFLAGS += -DNETNS_RUN_DIR=\"/run/netns\"
 CFLAGS += -DPASST_AUDIT_ARCH=AUDIT_ARCH_$(shell uname -m | tr [a-z] [A-Z])
 
+# On gcc 11.2, with -O2 and -flto, tcp_hash() and siphash_20b(), if inlined,
+# seem to be hitting something similar to:
+#	https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78993
+# from the pointer arithmetic used from the tcp_tap_handler() path to get the
+# remote connection address.
+ifeq ($(shell $(CC) -dumpversion),11)
+ifneq (,$(filter -flto%,$(CFLAGS)))
+ifneq (,$(filter -O2,$(CFLAGS)))
+	CFLAGS += -DTCP_HASH_NOINLINE
+	CFLAGS += -DSIPHASH_20B_NOINLINE
+endif
+endif
+endif
+
 prefix ?= /usr/local
 
 all: passt pasta passt4netns qrap
diff --git a/passt.c b/passt.c
index a5f9bf8..846ba7f 100644
--- a/passt.c
+++ b/passt.c
@@ -257,13 +257,16 @@ static void pid_file(struct ctx *c) {
 	if (!*c->pid_file)
 		return;
 
-	pid_fd = open(c->pid_file, O_CREAT | O_WRONLY);
+	pid_fd = open(c->pid_file, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR);
 	if (pid_fd < 0)
 		return;
 
 	n = snprintf(pid_buf, sizeof(pid_buf), "%i\n", getpid());
 
-	write(pid_fd, pid_buf, n);
+	if (write(pid_fd, pid_buf, n) < 0) {
+		perror("PID file write");
+		exit(EXIT_FAILURE);
+	}
 	close(pid_fd);
 }
 
@@ -365,8 +368,10 @@ int main(int argc, char **argv)
 	else
 		__setlogmask(LOG_UPTO(LOG_INFO));
 
-	if (isatty(fileno(stdout)) && !c.foreground)
-		daemon(0, 0);
+	if (isatty(fileno(stdout)) && !c.foreground && daemon(0, 0)) {
+		perror("daemon");
+		exit(EXIT_FAILURE);
+	}
 
 	pid_file(&c);
 
diff --git a/pasta.c b/pasta.c
index fe0bf0e..395f459 100644
--- a/pasta.c
+++ b/pasta.c
@@ -184,7 +184,8 @@ void pasta_start_ns(struct ctx *c)
 
 		snprintf(proc_path, PATH_MAX, "/proc/%i/ns/net",
 			 pasta_child_pid);
-		readlink(proc_path, pasta_child_ns, PATH_MAX);
+		if (readlink(proc_path, pasta_child_ns, PATH_MAX) < 0)
+			warn("Cannot read link to ns, won't clean up on exit");
 
 		return;
 	}
@@ -198,20 +199,24 @@ void pasta_start_ns(struct ctx *c)
 		snprintf(buf, BUFSIZ, "%u %u %u", 0, euid, 1);
 
 		fd = open("/proc/self/uid_map", O_WRONLY);
-		write(fd, buf, strlen(buf));
+		if (write(fd, buf, strlen(buf)) < 0)
+			warn("Cannot set uid_map in namespace");
 		close(fd);
 
 		fd = open("/proc/self/setgroups", O_WRONLY);
-		write(fd, "deny", sizeof("deny"));
+		if (write(fd, "deny", sizeof("deny")))
+			warn("Cannot write to setgroups in namespace");
 		close(fd);
 
 		fd = open("/proc/self/gid_map", O_WRONLY);
-		write(fd, buf, strlen(buf));
+		if (write(fd, buf, strlen(buf)) < 0)
+			warn("Cannot set gid_map in namespace");
 		close(fd);
 	}
 
 	fd = open("/proc/sys/net/ipv4/ping_group_range", O_WRONLY);
-	write(fd, "0 0", strlen("0 0"));
+	if (write(fd, "0 0", strlen("0 0")) < 0)
+		warn("Cannot set ping_group_range, ICMP requests might fail");
 	close(fd);
 
 	shell = getenv("SHELL") ? getenv("SHELL") : "/bin/sh";
diff --git a/pcap.c b/pcap.c
index 9cf585f..8ff1636 100644
--- a/pcap.c
+++ b/pcap.c
@@ -23,6 +23,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <time.h>
+#include <errno.h>
 #include <net/ethernet.h>
 #include <netinet/in.h>
 #include <unistd.h>
@@ -87,8 +88,8 @@ void pcap(char *pkt, size_t len)
 	h.tv_usec = tv.tv_usec;
 	h.caplen = h.len = len;
 
-	write(pcap_fd, &h, sizeof(h));
-	write(pcap_fd, pkt, len);
+	if (write(pcap_fd, &h, sizeof(h)) < 0 || write(pcap_fd, pkt, len) < 0)
+		debug("Cannot log packet, length %u", len);
 }
 
 /**
@@ -98,6 +99,7 @@ void pcap(char *pkt, size_t len)
 void pcapm(struct msghdr *mh)
 {
 	struct pcap_pkthdr h;
+	struct iovec *iov;
 	struct timeval tv;
 	unsigned int i;
 
@@ -109,13 +111,19 @@ void pcapm(struct msghdr *mh)
 	h.tv_usec = tv.tv_usec;
 
 	for (i = 0; i < mh->msg_iovlen; i++) {
-		struct iovec *iov = &mh->msg_iov[i];
+		iov = &mh->msg_iov[i];
 
 		h.caplen = h.len = iov->iov_len - 4;
-		write(pcap_fd, &h, sizeof(h));
 
-		write(pcap_fd, (char *)iov->iov_base + 4, iov->iov_len - 4);
+		if (write(pcap_fd, &h, sizeof(h)) < 0)
+			goto fail;
+		if (write(pcap_fd, (char *)iov->iov_base + 4, iov->iov_len - 4))
+			goto fail;
 	}
+
+	return;
+fail:
+	debug("Cannot log packet, length %u", iov->iov_len - 4);
 }
 
 /**
@@ -125,6 +133,7 @@ void pcapm(struct msghdr *mh)
 void pcapmm(struct mmsghdr *mmh, unsigned int vlen)
 {
 	struct pcap_pkthdr h;
+	struct iovec *iov;
 	struct timeval tv;
 	unsigned int i, j;
 
@@ -139,15 +148,20 @@ void pcapmm(struct mmsghdr *mmh, unsigned int vlen)
 		struct msghdr *mh = &mmh[i].msg_hdr;
 
 		for (j = 0; j < mh->msg_iovlen; j++) {
-			struct iovec *iov = &mh->msg_iov[j];
+			iov = &mh->msg_iov[j];
 
 			h.caplen = h.len = iov->iov_len - 4;
-			write(pcap_fd, &h, sizeof(h));
 
-			write(pcap_fd, (char *)iov->iov_base + 4,
-			      iov->iov_len - 4);
+			if (write(pcap_fd, &h, sizeof(h)) < 0)
+				goto fail;
+			if (write(pcap_fd, (char *)iov->iov_base + 4,
+				  iov->iov_len - 4) < 0)
+				goto fail;
 		}
 	}
+	return;
+fail:
+	debug("Cannot log packet, length %u", iov->iov_len - 4);
 }
 
 /**
@@ -194,5 +208,6 @@ void pcap_init(struct ctx *c, int index)
 
 	info("Saving packet capture at %s", c->pcap);
 
-	write(pcap_fd, &pcap_hdr, sizeof(pcap_hdr));
+	if (write(pcap_fd, &pcap_hdr, sizeof(pcap_hdr)) < 0)
+		warn("Cannot write PCAP header: %s", strerror(errno));
 }
diff --git a/siphash.c b/siphash.c
index b7a7861..88f8bd2 100644
--- a/siphash.c
+++ b/siphash.c
@@ -146,6 +146,9 @@ uint32_t siphash_12b(const uint8_t *in, const uint64_t *k)
  *
  * Return: the 64-bit hash output
  */
+#if SIPHASH_20B_NOINLINE
+__attribute__((__noinline__))	/* See comment in Makefile */
+#endif
 uint64_t siphash_20b(const uint8_t *in, const uint64_t *k)
 {
 	uint32_t *in32 = (uint32_t *)in;
diff --git a/tcp.c b/tcp.c
index 0093ec4..99674ef 100644
--- a/tcp.c
+++ b/tcp.c
@@ -311,6 +311,7 @@
 #include <sched.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <errno.h>
 #include <limits.h>
 #include <net/ethernet.h>
@@ -1103,6 +1104,9 @@ static int tcp_hash_match(struct tcp_tap_conn *conn, int af, void *addr,
  *
  * Return: hash value, already modulo size of the hash table
  */
+#if TCP_HASH_NOINLINE
+__attribute__((__noinline__))	/* See comment in Makefile */
+#endif
 static unsigned int tcp_hash(struct ctx *c, int af, void *addr,
 			     in_port_t tap_port, in_port_t sock_port)
 {
@@ -1322,8 +1326,9 @@ static void tcp_l2_flags_buf_flush(struct ctx *c)
 			for (i = 0; i < mh.msg_iovlen; i++) {
 				struct iovec *iov = &mh.msg_iov[i];
 
-				write(c->fd_tap, (char *)iov->iov_base + 4,
-				      iov->iov_len - 4);
+				if (write(c->fd_tap, (char *)iov->iov_base + 4,
+					  iov->iov_len - 4) < 0)
+					debug("tap write: %s", strerror(errno));
 			}
 		}
 		tcp6_l2_flags_buf_used = 0;
@@ -1338,8 +1343,9 @@ static void tcp_l2_flags_buf_flush(struct ctx *c)
 			for (i = 0; i < mh.msg_iovlen; i++) {
 				struct iovec *iov = &mh.msg_iov[i];
 				
-				write(c->fd_tap, (char *)iov->iov_base + 4,
-				      iov->iov_len - 4);
+				if (write(c->fd_tap, (char *)iov->iov_base + 4,
+					  iov->iov_len - 4) < 0)
+					debug("tap write: %s", strerror(errno));
 			}
 		}
 		tcp4_l2_flags_buf_used = 0;
@@ -1392,8 +1398,9 @@ static void tcp_l2_buf_flush(struct ctx *c)
 		for (i = 0; i < mh.msg_iovlen; i++) {
 			struct iovec *iov = &mh.msg_iov[i];
 
-			write(c->fd_tap, (char *)iov->iov_base + 4,
-			      iov->iov_len - 4);
+			if (write(c->fd_tap, (char *)iov->iov_base + 4,
+				  iov->iov_len - 4) < 0)
+				debug("tap write: %s", strerror(errno));
 		}
 	}
 	tcp6_l2_buf_used = tcp6_l2_buf_bytes = 0;
@@ -1413,8 +1420,9 @@ v4:
 		for (i = 0; i < mh.msg_iovlen; i++) {
 			struct iovec *iov = &mh.msg_iov[i];
 
-			write(c->fd_tap, (char *)iov->iov_base + 4,
-			      iov->iov_len - 4);
+			if (write(c->fd_tap, (char *)iov->iov_base + 4,
+				  iov->iov_len - 4) < 0)
+				debug("tap write: %s", strerror(errno));
 		}
 	}
 	tcp4_l2_buf_used = tcp4_l2_buf_bytes = 0;
@@ -1628,14 +1636,16 @@ static int tcp_send_to_tap(struct ctx *c, struct tcp_tap_conn *conn, int flags,
 		iov = tcp4_l2_flags_iov_tap + tcp4_l2_flags_buf_used;
 		p = b4 = tcp4_l2_flags_buf  + tcp4_l2_flags_buf_used++;
 		th = &b4->th;
+
+		/* gcc 11.2 would complain on data = (char *)(th + 1); */
+		data = b4->opts;
 	} else {
 		iov = tcp6_l2_flags_iov_tap + tcp6_l2_flags_buf_used;
 		p = b6 = tcp6_l2_flags_buf  + tcp6_l2_flags_buf_used++;
 		th = &b6->th;
+		data = b6->opts;
 	}
 
-	data = (char *)(th + 1);
-
 	if (flags & SYN) {
 		uint16_t mss;
 
@@ -3538,7 +3548,11 @@ int tcp_sock_init(struct ctx *c, struct timespec *now)
 	in_port_t port;
 	int i;
 
-	getrandom(&c->tcp.hash_secret, sizeof(c->tcp.hash_secret), GRND_RANDOM);
+	if (getrandom(&c->tcp.hash_secret, sizeof(c->tcp.hash_secret),
+		      GRND_RANDOM) < 0) {
+		perror("TCP initial sequence getrandom");
+		exit(EXIT_FAILURE);
+	}
 
 	for (port = 0; port < USHRT_MAX; port++) {
 		if (!bitmap_isset(c->tcp.port_to_tap, port))
diff --git a/udp.c b/udp.c
index ceb10a6..5c0e955 100644
--- a/udp.c
+++ b/udp.c
@@ -536,8 +536,8 @@ static void udp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 				    uint32_t events, struct timespec *now)
 {
 	struct msghdr *mh = &udp_splice_mmh_recv[0].msg_hdr;
+	in_port_t src, dst = ref.udp.port, send_dst = 0;
 	struct sockaddr_storage *sa_s = mh->msg_name;
-	in_port_t src, dst = ref.udp.port, send_dst;
 	int s, v6 = ref.udp.v6, n, i;
 
 	if (!(events & EPOLLIN))
@@ -721,7 +721,8 @@ void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 
 			if (c->mode == MODE_PASTA) {
 				ip_len += sizeof(struct ethhdr);
-				write(c->fd_tap, &b->eh, ip_len);
+				if (write(c->fd_tap, &b->eh, ip_len) < 0)
+					debug("tap write: %s", strerror(errno));
 				pcap((char *)&b->eh, ip_len);
 				continue;
 			}
@@ -791,7 +792,8 @@ void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 
 			if (c->mode == MODE_PASTA) {
 				ip_len += sizeof(struct ethhdr);
-				write(c->fd_tap, &b->eh, ip_len);
+				if (write(c->fd_tap, &b->eh, ip_len) < 0)
+					debug("tap write: %s", strerror(errno));
 				pcap((char *)&b->eh, ip_len);
 				continue;
 			}