helper

random_challs/mad_seccomp/read_file.c

@@ -0,0 +1,44 @@
+#include <sys/syscall.h>
+#include <stdio.h>
+#include <linux/openat2.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+
+int main(void){
+	// get syscall num
+	printf("openat2: %d\n", SYS_openat2);
+	printf("pread64: %d\n", SYS_pread64);
+	printf("writev: %d\n", SYS_writev);
+
+	// struct
+	struct open_how how;
+	memset(&how, 0, sizeof(how));
+	how.flags = O_RDWR;
+	how.resolve = RESOLVE_IN_ROOT;
+	size_t size = sizeof(how);
+
+	// openat2
+	const char *file = "flag.txt";
+	long rax = syscall(SYS_openat2, AT_FDCWD, file, &how, size);
+	printf("fd: %d\n", rax);
+
+	// pread64
+	char buf[64];
+	long rax2 = syscall(SYS_pread64, rax, buf, 100, 0);
+	printf("string size: %d\n", rax2);
+
+	// struct
+	char *str = "Some string here";
+	struct iovec {
+	    void  *iov_base;
+	    size_t iov_len;
+	};
+	struct iovec iov[1];
+	iov[0].iov_base = str;
+	iov[0].iov_len = strlen(str);
+
+	// writev
+	syscall(SYS_writev, 1, iov, 1);
+	return 0;
+}