[PATCH v4 08/17] pesto: Introduce stub configuration tool

[David Gibson <david@gibson.dropbear.id.au>]

Build a new "pesto" binary, which will become the tool to update a running
passt/pasta's configuration.  For now, we just build a stub binary which
sets up a basic environment, parses trivial command line options but does
nothing else.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 .gitignore |   2 +
 Makefile   |  42 +++++++++++------
 common.h   |  24 ++++++++++
 pesto.1    |  46 +++++++++++++++++++
 pesto.c    | 132 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 pesto.h    |  12 +++++
 util.h     |  12 +----
 7 files changed, 244 insertions(+), 26 deletions(-)
 create mode 100644 common.h
 create mode 100644 pesto.1
 create mode 100644 pesto.c
 create mode 100644 pesto.h

diff --git a/.gitignore b/.gitignore
index 3c16adc7..3e40d9f7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,9 +4,11 @@
 /pasta
 /pasta.avx2
 /passt-repair
+/pesto
 /qrap
 /pasta.1
 /seccomp.h
+/seccomp_pesto.h
 /seccomp_repair.h
 /c*.json
 README.plain.md
diff --git a/Makefile b/Makefile
index 7875d23b..030681b1 100644
--- a/Makefile
+++ b/Makefile
@@ -47,19 +47,21 @@ PASST_SRCS = arch.c arp.c bitmap.c checksum.c conf.c dhcp.c dhcpv6.c \
 	vhost_user.c virtio.c vu_common.c
 QRAP_SRCS = qrap.c
 PASST_REPAIR_SRCS = passt-repair.c
-SRCS = $(PASST_SRCS) $(QRAP_SRCS) $(PASST_REPAIR_SRCS)
-
-MANPAGES = passt.1 pasta.1 qrap.1 passt-repair.1
-
-PASST_HEADERS = arch.h arp.h bitmap.h checksum.h conf.h dhcp.h dhcpv6.h \
-	epoll_ctl.h flow.h fwd.h fwd_rule.h flow_table.h icmp.h icmp_flow.h \
-	inany.h iov.h ip.h isolation.h lineread.h log.h migrate.h ndp.h \
-	netlink.h packet.h passt.h pasta.h pcap.h pif.h repair.h serialise.h \
-	siphash.h tap.h tcp.h tcp_buf.h tcp_conn.h tcp_internal.h tcp_splice.h \
-	tcp_vu.h udp.h udp_flow.h udp_internal.h udp_vu.h util.h vhost_user.h \
-	virtio.h vu_common.h
+PESTO_SRCS = pesto.c
+SRCS = $(PASST_SRCS) $(QRAP_SRCS) $(PASST_REPAIR_SRCS) $(PESTO_SRCS)
+
+MANPAGES = passt.1 pasta.1 pesto.1 qrap.1 passt-repair.1
+
+PASST_HEADERS = arch.h arp.h bitmap.h checksum.h common.h conf.h dhcp.h \
+	dhcpv6.h epoll_ctl.h flow.h fwd.h fwd_rule.h flow_table.h icmp.h \
+	icmp_flow.h inany.h iov.h ip.h isolation.h lineread.h log.h migrate.h \
+	ndp.h netlink.h packet.h passt.h pasta.h pcap.h pesto.h pif.h repair.h \
+	serialise.h siphash.h tap.h tcp.h tcp_buf.h tcp_conn.h tcp_internal.h \
+	tcp_splice.h tcp_vu.h udp.h udp_flow.h udp_internal.h udp_vu.h util.h \
+	vhost_user.h virtio.h vu_common.h
 QRAP_HEADERS = arp.h ip.h passt.h util.h
 PASST_REPAIR_HEADERS = linux_dep.h
+PESTO_HEADERS = common.h pesto.h
 
 C := \#include <sys/random.h>\nint main(){int a=getrandom(0, 0, 0);}
 ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
@@ -78,7 +80,7 @@ docdir		?= $(datarootdir)/doc/passt
 mandir		?= $(datarootdir)/man
 man1dir		?= $(mandir)/man1
 
-BASEBIN = passt qrap passt-repair
+BASEBIN = passt qrap passt-repair pesto
 ifeq ($(TARGET_ARCH),x86_64)
 BASEBIN += passt.avx2
 endif
@@ -100,6 +102,9 @@ seccomp.h: seccomp.sh $(PASST_SRCS) $(PASST_HEADERS)
 seccomp_repair.h: seccomp.sh $(PASST_REPAIR_SRCS) $(PASST_REPAIR_HEADERS)
 	@ ARCH="$(TARGET_ARCH)" CC="$(CC)" ./seccomp.sh seccomp_repair.h $(PASST_REPAIR_SRCS)
 
+seccomp_pesto.h: seccomp.sh $(PESTO_SRCS)
+	@ ARCH="$(TARGET_ARCH)" CC="$(CC)" ./seccomp.sh seccomp_pesto.h $(PESTO_SRCS)
+
 $(BASEBIN): %:
 	$(CC) $(BASE_CPPFLAGS) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) $(filter %.c,$^) -o $@
 
@@ -116,6 +121,8 @@ qrap: $(QRAP_SRCS) $(QRAP_HEADERS)
 
 passt-repair: $(PASST_REPAIR_SRCS) $(PASST_REPAIR_HEADERS) seccomp_repair.h
 
+pesto: $(PESTO_SRCS) $(PESTO_HEADERS) seccomp_pesto.h
+
 valgrind: EXTRA_SYSCALLS += rt_sigprocmask rt_sigtimedwait rt_sigaction	\
 			    rt_sigreturn getpid gettid kill clock_gettime \
 			    mmap|mmap2 munmap open unlink gettimeofday futex \
@@ -126,7 +133,7 @@ valgrind: all
 
 .PHONY: clean
 clean:
-	$(RM) $(BIN) *~ *.o seccomp.h seccomp_repair.h pasta.1 \
+	$(RM) $(BIN) *~ *.o seccomp.h seccomp_repair.h seccomp_pesto.h pasta.1 \
 		passt.tar passt.tar.gz *.deb *.rpm \
 		passt.pid README.plain.md
 
@@ -183,7 +190,8 @@ docs: README.md
 CLANG_TIDY = clang-tidy
 CLANG_TIDY_FLAGS = -DCLANG_TIDY_58992
 
-clang-tidy: passt.clang-tidy passt-repair.clang-tidy qrap.clang-tidy
+clang-tidy: passt.clang-tidy passt-repair.clang-tidy pesto.clang-tidy \
+	qrap.clang-tidy
 
 .PHONY: %.clang-tidy
 %.clang-tidy:
@@ -191,6 +199,7 @@ clang-tidy: passt.clang-tidy passt-repair.clang-tidy qrap.clang-tidy
 
 passt.clang-tidy: $(PASST_SRCS) $(PASST_HEADERS) seccomp.h
 passt-repair.clang-tidy: $(PASST_REPAIR_SRCS) $(PASST_REPAIR_HEADERS) seccomp_repair.h
+pesto.clang-tidy: $(PESTO_SRCS) $(PESTO_HEADERS) seccomp_pesto.h
 qrap.clang-tidy: $(QRAP_SRCS) $(QRAP_HEADERS)
 
 CPPCHECK = cppcheck
@@ -206,7 +215,7 @@ CPPCHECK_FLAGS = --std=c11 --error-exitcode=1 --enable=all --force	\
 	--suppress=unusedStructMember					\
 	 -D CPPCHECK_6936
 
-cppcheck: passt.cppcheck passt-repair.cppcheck qrap.cppcheck
+cppcheck: passt.cppcheck passt-repair.cppcheck pesto.cppcheck qrap.cppcheck
 
 .PHONY: %.cppcheck
 %.cppcheck:
@@ -215,6 +224,9 @@ cppcheck: passt.cppcheck passt-repair.cppcheck qrap.cppcheck
 passt.cppcheck: $(PASST_SRCS) $(PASST_HEADERS) seccomp.h
 passt-repair.cppcheck: $(PASST_REPAIR_SRCS) $(PASST_REPAIR_HEADERS) seccomp_repair.h
 
+pesto.cppcheck: CPPCHECK_FLAGS += --suppress=unmatchedSuppression
+pesto.cppcheck: $(PESTO_SRCS) $(PESTO_HEADERS) seccomp_pesto.h
+
 qrap.cppcheck: BASE_CPPFLAGS += -DARCH=\"$(TARGET_ARCH)\"
 qrap.cppcheck: CPPCHECK_FLAGS += --suppress=unusedFunction
 qrap.cppcheck: $(QRAP_SRCS) $(QRAP_HEADERS)
diff --git a/common.h b/common.h
new file mode 100644
index 00000000..a9c115a5
--- /dev/null
+++ b/common.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright Red Hat
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ *
+ * Definitions used by both passt/pasta and other tools
+ */
+
+#ifndef COMMON_H
+#define COMMON_H
+
+#include <string.h>
+
+#define VERSION_BLOB							       \
+	VERSION "\n"							       \
+	"Copyright Red Hat\n"						       \
+	"GNU General Public License, version 2 or later\n"		       \
+	"  <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>\n"	       \
+	"This is free software: you are free to change and redistribute it.\n" \
+	"There is NO WARRANTY, to the extent permitted by law.\n\n"
+
+/* FPRINTF() intentionally silences cert-err33-c clang-tidy warnings */
+#define FPRINTF(f, ...)	(void)fprintf(f, __VA_ARGS__)
+
+#endif /* _COMMON_H */
diff --git a/pesto.1 b/pesto.1
new file mode 100644
index 00000000..338fb8a6
--- /dev/null
+++ b/pesto.1
@@ -0,0 +1,46 @@
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\" Copyright Red Hat
+.\" Author: David Gibson <david@gibson.dropbear.id.au>
+.TH pesto 1
+
+.SH NAME
+.B pesto
+\- Configure a running \fBpasst\fR(1) or \fBpasta\fR(1) instance.
+
+.SH SYNOPSIS
+.B pesto
+\fIPATH\fR
+
+.SH DESCRIPTION
+
+.B pesto
+is an experimental client to view and update the port forwarding
+configuration of a running \fBpasst\fR(1) or \fBpasta\fR(1) instance.
+
+\fIPATH\fR gives the path to the UNIX domain socket created by
+\fBpasst\fR or \fBpasta\fR.  It should match the \fB-c\fR command line
+option given to that instance.
+
+.SH AUTHORS
+
+Stefano Brivio <sbrivio@redhat.com>,
+David Gibson <david@gibson.dropbear.id.au>.
+
+.SH REPORTING BUGS
+
+Please report issues on the bug tracker at https://bugs.passt.top/, or
+send a message to the passt-user@passt.top mailing list, see
+https://lists.passt.top/.
+
+.SH COPYRIGHT
+
+Copyright Red Hat
+
+\fBpesto\fR is free software: you can redistribute them and/or modify
+them under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or (at
+your option) any later version.
+
+.SH SEE ALSO
+
+\fBpasst\fR(1), \fBpasta\fR(1), \fBunix\fR(7).
diff --git a/pesto.c b/pesto.c
new file mode 100644
index 00000000..9f2fa5d5
--- /dev/null
+++ b/pesto.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* PESTO - Programmable Extensible Socket Translation Orchestrator
+ *  front-end for passt(1) and pasta(1) forwarding configuration
+ *
+ * pesto.c - Main program (it's not actually extensible)
+ *
+ * Copyright (c) 2026 Red Hat GmbH
+ * Author: Stefano Brivio <sbrivio@redhat.com>
+ */
+
+#include <arpa/inet.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <errno.h>
+#include <getopt.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <unistd.h>
+
+#include <linux/audit.h>
+#include <linux/capability.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+
+#include "common.h"
+#include "seccomp_pesto.h"
+#include "pesto.h"
+
+static bool debug_flag = false;
+
+static char stdout_buf[BUFSIZ];
+
+#define die(...)							\
+	do {								\
+		FPRINTF(stderr, __VA_ARGS__);				\
+		FPRINTF(stderr, "\n");					\
+		exit(EXIT_FAILURE);					\
+	} while (0)
+
+/**
+ * usage() - Print usage, exit with given status code
+ * @name:	Executable name
+ * @f:		Stream to print usage info to
+ * @status:	Status code for exit(2)
+ *
+ * #syscalls:pesto exit_group fstat write
+ */
+static void usage(const char *name, FILE *f, int status)
+{
+	FPRINTF(f, "Usage: %s [OPTION]... PATH\n", name);
+	FPRINTF(f,
+		"\n"
+		"  -d, --debug		Print debugging messages\n"
+		"  -h, --help		Display this help message and exit\n"
+		"  --version		Show version and exit\n");
+	exit(status);
+}
+
+/**
+ * main() - Dynamic reconfiguration client main program
+ * @argc:	Argument count
+ * @argv:	Arguments: socket path, operation, port specifiers
+ *
+ * Return: 0 on success, won't return on failure
+ *
+ * #syscalls:pesto exit_group fstat read write
+ */
+int main(int argc, char **argv)
+{
+	const struct option options[] = {
+		{"debug",	no_argument,		NULL,		'd' },
+		{"help",	no_argument,		NULL,		'h' },
+		{"version",	no_argument,		NULL,		1 },
+		{ 0 },
+	};
+	const char *optstring = "dh";
+	struct sock_fprog prog;
+	int optname;
+
+	prctl(PR_SET_DUMPABLE, 0);
+
+	prog.len = (unsigned short)sizeof(filter_pesto) /
+				   sizeof(filter_pesto[0]);
+	prog.filter = filter_pesto;
+	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) ||
+	    prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog))
+		die("Failed to apply seccomp filter");
+
+	/* Explicitly set stdout buffer, otherwise printf() might allocate,
+	 * breaking our seccomp profile.
+	 */
+	if (setvbuf(stdout, stdout_buf, _IOFBF, sizeof(stdout_buf)))
+		die("Failed to set stdout buffer");
+
+	do {
+		optname = getopt_long(argc, argv, optstring, options, NULL);
+
+		switch (optname) {
+		case -1:
+		case 0:
+			break;
+		case 'h':
+			usage(argv[0], stdout, EXIT_SUCCESS);
+			break;
+		case 'd':
+			debug_flag = true;
+			break;
+		case 1:
+			FPRINTF(stdout, "pesto ");
+			FPRINTF(stdout, VERSION_BLOB);
+			exit(EXIT_SUCCESS);
+		default:
+			usage(argv[0], stderr, EXIT_FAILURE);
+		}
+	} while (optname != -1);
+
+	if (argc - optind != 1)
+		usage(argv[0], stderr, EXIT_FAILURE);
+
+	printf("debug_flag=%d, path=\"%s\"\n", debug_flag, argv[optind]);
+
+	die("pesto is not implemented yet");
+}
diff --git a/pesto.h b/pesto.h
new file mode 100644
index 00000000..e9b329f4
--- /dev/null
+++ b/pesto.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright Red Hat
+ * Author: David Gibson <david@gibson.dropbear.id.au>
+ *
+ * Definitions and functions used by both client and server of the configuration
+ * update protocol (pesto).
+ */
+
+#ifndef PESTO_H
+#define PESTO_H
+
+#endif /* PESTO_H */
diff --git a/util.h b/util.h
index 92aeabc8..770ff93f 100644
--- a/util.h
+++ b/util.h
@@ -19,16 +19,9 @@
 #include <sys/syscall.h>
 #include <net/ethernet.h>
 
+#include "common.h"
 #include "log.h"
 
-#define VERSION_BLOB							       \
-	VERSION "\n"							       \
-	"Copyright Red Hat\n"						       \
-	"GNU General Public License, version 2 or later\n"		       \
-	"  <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>\n"	       \
-	"This is free software: you are free to change and redistribute it.\n" \
-	"There is NO WARRANTY, to the extent permitted by law.\n\n"
-
 #ifndef SECCOMP_RET_KILL_PROCESS
 #define SECCOMP_RET_KILL_PROCESS	SECCOMP_RET_KILL
 #endif
@@ -307,9 +300,6 @@ static inline bool mod_between(unsigned x, unsigned i, unsigned j, unsigned m)
 	return mod_sub(x, i, m) < mod_sub(j, i, m);
 }
 
-/* FPRINTF() intentionally silences cert-err33-c clang-tidy warnings */
-#define FPRINTF(f, ...)	(void)fprintf(f, __VA_ARGS__)
-
 void raw_random(void *buf, size_t buflen);
 
 /*
-- 
2.53.0