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-rw-r--r--src/eater/Makefile22
-rw-r--r--src/eater/eater.c143
2 files changed, 165 insertions, 0 deletions
diff --git a/src/eater/Makefile b/src/eater/Makefile
new file mode 100644
index 0000000..c70433f
--- /dev/null
+++ b/src/eater/Makefile
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# seitan - Syscall Expressive Interpreter, Transformer and Notifier
+#
+# eater/Makefile - Makefile for seitan-eater
+#
+# Copyright 2023 Red Hat GmbH
+# Author: Alice Frosi <afrosi@redhat.com>
+
+COMMON_DIR :=../common
+SRCS := $(COMMON_DIR)/common.c eater.c
+HEADERS := $(COMMON_DIR)/common.h
+BIN := $(OUTDIR)eater
+CFLAGS += -Wall -Wextra -pedantic -I$(COMMON_DIR)
+
+eater: $(SRCS) $(HEADERS)
+ $(CC) $(CFLAGS) -o $(BIN) $(SRCS)
+
+all: eater
+
+clean:
+ rm -f $(BIN)
diff --git a/src/eater/eater.c b/src/eater/eater.c
new file mode 100644
index 0000000..96a7b61
--- /dev/null
+++ b/src/eater/eater.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+/* SEITAN - Syscall Expressive Interpreter, Transformer and Notifier
+ *
+ * src/eater/eater.c - Load BPF program and execute binary
+ *
+ * Copyright (c) 2022 Red Hat GmbH
+ * Authors: Stefano Brivio <sbrivio@redhat.com>, Alice Frosi <afrosi@redhat.com>
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <argp.h>
+#include <sys/prctl.h>
+#include <sys/syscall.h>
+#include <sys/socket.h>
+#include <signal.h>
+
+#include <linux/audit.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+
+#include <dirent.h>
+#include <sys/stat.h>
+
+#include "common.h"
+
+extern char **environ;
+
+static char doc[] =
+ "Usage: seitan-eater: setain-eater -i <input file> -- program args1 args2...";
+
+/* Eater options */
+static struct argp_option options[] = { { "input", 'i', "FILE", 0,
+ "BPF filter input file", 0 },
+ { 0 } };
+
+struct arguments {
+ char *input_file;
+ unsigned int program_index;
+};
+
+static error_t parse_opt(int key, char *arg, struct argp_state *state)
+{
+ struct arguments *arguments = state->input;
+
+ if (state->quoted == 0)
+ arguments->program_index = state->next + 1;
+ switch (key) {
+ case 'i':
+ if (state->quoted == 0)
+ arguments->input_file = arg;
+ break;
+ case ARGP_KEY_END:
+ if (arguments->input_file == NULL)
+ argp_error(state, "missing input file");
+ if (state->argv[arguments->program_index] == NULL)
+ argp_error(state, "missing program");
+ break;
+ }
+
+ return 0;
+}
+
+static struct argp argp = { .options = options,
+ .parser = parse_opt,
+ .args_doc = NULL,
+ .doc = doc,
+ .children = NULL,
+ .help_filter = NULL,
+ .argp_domain = NULL };
+
+static int seccomp(unsigned int operation, unsigned int flags, void *args)
+{
+ return syscall(__NR_seccomp, operation, flags, args);
+}
+
+static void signal_handler(__attribute__((unused)) int s)
+{
+}
+
+/**
+ * main() - Entry point
+ * @argc: Argument count
+ * @argv: Seitan-eater and program arguments
+ *
+ * Return: 0 once interrupted, non-zero on failure
+ */
+int main(int argc, char **argv)
+{
+ struct sock_filter filter[1024];
+ struct arguments arguments;
+ struct sock_fprog prog;
+ struct sigaction act;
+ size_t n;
+ int fd, flags;
+
+ argp_parse(&argp, argc, argv, 0, 0, &arguments);
+ fd = open(arguments.input_file, O_CLOEXEC | O_RDONLY);
+ n = read(fd, filter, sizeof(filter));
+ close(fd);
+
+ prog.filter = filter;
+ prog.len = (unsigned short)(n / sizeof(filter[0]));
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
+ perror("prctl");
+ exit(EXIT_FAILURE);
+ }
+ if (seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FILTER_FLAG_NEW_LISTENER,
+ &prog) < 0) {
+ perror("seccomp");
+ exit(EXIT_FAILURE);
+ }
+ /*
+ * close-on-exec flag is set for the file descriptor by seccomp.
+ * We want to preserve the fd on the exec in this way we are able
+ * to easly find the notifier fd if seitan restarts.
+ */
+ fd = find_fd_seccomp_notifier("/proc/self/fd");
+ flags = fcntl(fd, F_GETFD);
+ if (fcntl(fd, F_SETFD, flags & !FD_CLOEXEC) < 0) {
+ perror("fcntl");
+ exit(EXIT_FAILURE);
+ }
+ act.sa_handler = signal_handler;
+ sigaction(SIGCONT, &act, NULL);
+ pause();
+
+ execvpe(argv[arguments.program_index], &argv[arguments.program_index],
+ environ);
+ if (errno != ENOENT) {
+ perror("execvpe");
+ exit(EXIT_FAILURE);
+ }
+ close(fd);
+ return EXIT_FAILURE;
+}