A privileged helper to set/clear TCP_REPAIR on sockets on behalf of
passt. Not used yet.
Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
---
Makefile | 10 +++--
passt-repair.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 124 insertions(+), 3 deletions(-)
create mode 100644 passt-repair.c
diff --git a/Makefile b/Makefile
index 1383875..1b71cb0 100644
--- a/Makefile
+++ b/Makefile
@@ -42,7 +42,8 @@ PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c flow.c fwd.c
\
tcp.c tcp_buf.c tcp_splice.c tcp_vu.c udp.c udp_flow.c udp_vu.c util.c \
vhost_user.c virtio.c vu_common.c
QRAP_SRCS = qrap.c
-SRCS = $(PASST_SRCS) $(QRAP_SRCS)
+PASST_REPAIR_SRCS = passt-repair.c
+SRCS = $(PASST_SRCS) $(QRAP_SRCS) $(PASST_REPAIR_SRCS)
MANPAGES = passt.1 pasta.1 qrap.1
@@ -72,9 +73,9 @@ mandir ?= $(datarootdir)/man
man1dir ?= $(mandir)/man1
ifeq ($(TARGET_ARCH),x86_64)
-BIN := passt passt.avx2 pasta pasta.avx2 qrap
+BIN := passt passt.avx2 pasta pasta.avx2 qrap passt-repair
else
-BIN := passt pasta qrap
+BIN := passt pasta qrap passt-repair
endif
all: $(BIN) $(MANPAGES) docs
@@ -101,6 +102,9 @@ pasta.avx2 pasta.1 pasta: pasta%: passt%
qrap: $(QRAP_SRCS) passt.h
$(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) -DARCH=\"$(TARGET_ARCH)\" $(QRAP_SRCS) -o
qrap $(LDFLAGS)
+passt-repair: $(PASST_REPAIR_SRCS)
+ $(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) $(PASST_REPAIR_SRCS) -o passt-repair $(LDFLAGS)
+
valgrind: EXTRA_SYSCALLS += rt_sigprocmask rt_sigtimedwait rt_sigaction \
rt_sigreturn getpid gettid kill clock_gettime mmap \
mmap2 munmap open unlink gettimeofday futex statx \
diff --git a/passt-repair.c b/passt-repair.c
new file mode 100644
index 0000000..988a52c
--- /dev/null
+++ b/passt-repair.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* PASST - Plug A Simple Socket Transport
+ * for qemu/UNIX domain socket mode
+ *
+ * PASTA - Pack A Subtle Tap Abstraction
+ * for network namespace/tap device mode
+ *
+ * passt-repair.c - Privileged helper to set/clear TCP_REPAIR on sockets
+ *
+ * Copyright (c) 2025 Red Hat GmbH
+ * Author: Stefano Brivio <sbrivio(a)redhat.com>
+ *
+ * Connect to passt via UNIX domain socket, receive sockets via SCM_RIGHTS along
+ * with byte commands mapping to TCP_REPAIR values, and switch repair mode on or
+ * off. Reply by echoing the command. Exit on EOF.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <unistd.h>
+#include <netdb.h>
+
+#include <netinet/tcp.h>
+
+#define SCM_MAX_FD 253 /* From Linux kernel (include/net/scm.h), not in UAPI */
+
+int main(int argc, char **argv)
+{
+ char buf[CMSG_SPACE(sizeof(int) * SCM_MAX_FD)]
+ __attribute__ ((aligned(__alignof__(struct cmsghdr))));
+ struct sockaddr_un a = { AF_UNIX, "" };
+ int fds[SCM_MAX_FD], s, ret, i, n;
+ int8_t cmd = INT8_MAX;
+ struct cmsghdr *cmsg;
+ struct msghdr msg;
+ struct iovec iov;
+
+ iov = (struct iovec){ &cmd, sizeof(cmd) };
+ msg = (struct msghdr){ NULL, 0, &iov, 1, buf, sizeof(buf), 0 };
+ cmsg = CMSG_FIRSTHDR(&msg);
+
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s PATH\n", argv[0]);
+ return -1;
+ }
+
+ ret = snprintf(a.sun_path, sizeof(a.sun_path), "%s", argv[1]);
+ if (ret <= 0 || ret >= (int)sizeof(a.sun_path)) {
+ fprintf(stderr, "Invalid socket path: %s\n", argv[1]);
+ return -1;
+ }
+
+ if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
+ perror("Failed to create AF_UNIX socket");
+ return -1;
+ }
+
+ if (connect(s, (struct sockaddr *)&a, sizeof(a))) {
+ fprintf(stderr, "Failed to connect to %s: %s\n", argv[1],
+ strerror(errno));
+ return -1;
+ }
+
+loop:
+ ret = recvmsg(s, &msg, 0);
+ if (ret < 0) {
+ perror("Failed to receive message");
+ return -1;
+ }
+
+ if (!ret) /* Done */
+ return 0;
+
+ if (!cmsg ||
+ cmsg->cmsg_len < CMSG_LEN(sizeof(int)) ||
+ cmsg->cmsg_len > CMSG_LEN(sizeof(int) * SCM_MAX_FD) ||
+ cmsg->cmsg_type != SCM_RIGHTS)
+ return -1;
+
+ n = cmsg->cmsg_len / CMSG_LEN(sizeof(int));
+ memcpy(fds, CMSG_DATA(cmsg), sizeof(int) * n);
+
+ if (cmd != TCP_REPAIR_ON && cmd != TCP_REPAIR_OFF &&
+ cmd != TCP_REPAIR_OFF_NO_WP) {
+ fprintf(stderr, "Unsupported command 0x%04x\n", cmd);
+ return -1;
+ }
+
+ for (i = 0; i < n; i++) {
+ int o = cmd;
+
+ if (setsockopt(fds[i], SOL_TCP, TCP_REPAIR, &o, sizeof(o))) {
+ fprintf(stderr,
+ "Setting TCP_REPAIR to %i on socket %i: %s", o,
+ fds[i], strerror(errno));
+ return -1;
+ }
+
+ /* Confirm setting by echoing the command back */
+ if (send(s, &cmd, sizeof(cmd), 0) < 0) {
+ fprintf(stderr, "Reply to command %i: %s\n",
+ o, strerror(errno));
+ return -1;
+ }
+ }
+
+ goto loop;
+
+ return 0;
+}
--
2.43.0