amend gitignore

2026-07-23 15:23:47 +08:00
parent 6f34caf845
commit 3d62194fec
19 changed files with 875 additions and 597 deletions
@@ -0,0 +1,89 @@
+#include "container.h"
+#include "mount.h"
+
+static int pivot_root(const char *new_root, const char *put_old)
+{
+	return syscall(SYS_pivot_root, new_root, put_old);
+}
+
+int mounts(struct child_config *config)
+{
+	fprintf(stderr, "=> remounting everything with MS_PRIVATE...");
+	if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, NULL)) {
+		fprintf(stderr, "failed! %m\n");
+		return -1;
+	}
+	fprintf(stderr, "remounted.\n");
+
+	fprintf(stderr, "=> making a temp directory and a bind mount there...");
+	char mount_dir[] = "/tmp/tmp.XXXXXX";
+	if (!mkdtemp(mount_dir)) {
+		fprintf(stderr, "failed making a directory!\n");
+		return -1;
+	}
+
+	if (mount(config->mount_dir, mount_dir, NULL, MS_BIND | MS_PRIVATE, NULL)) {
+		fprintf(stderr, "bind mount failed!\n");
+		return -1;
+	}
+
+	char inner_mount_dir[] = "/tmp/tmp.XXXXXX/oldroot.XXXXXX";
+	memcpy(inner_mount_dir, mount_dir, sizeof(mount_dir) - 1);
+	if (!mkdtemp(inner_mount_dir)) {
+		fprintf(stderr, "failed making the inner directory!\n");
+		return -1;
+	}
+	fprintf(stderr, "done.\n");
+
+	fprintf(stderr, "=> pivoting root...");
+	if (pivot_root(mount_dir, inner_mount_dir)) {
+		fprintf(stderr, "failed!\n");
+		return -1;
+	}
+	fprintf(stderr, "done.\n");
+
+	char *old_root_dir = basename(inner_mount_dir);
+	char old_root[sizeof(inner_mount_dir) + 1] = { "/" };
+	strcpy(&old_root[1], old_root_dir);
+
+	fprintf(stderr, "=> unmounting %s...", old_root);
+	if (chdir("/")) {
+		fprintf(stderr, "chdir failed! %m\n");
+		return -1;
+	}
+	if (umount2(old_root, MNT_DETACH)) {
+		fprintf(stderr, "umount failed! %m\n");
+		return -1;
+	}
+	if (rmdir(old_root)) {
+		fprintf(stderr, "rmdir failed! %m\n");
+		return -1;
+	}
+	fprintf(stderr, "done.\n");
+
+	fprintf(stderr, "=> mounting /proc...");
+	if (mount("proc", "/proc", "proc", 0, NULL)) {
+		fprintf(stderr, "failed: %m\n");
+		return -1;
+	}
+	fprintf(stderr, "done.\n");
+
+	fprintf(stderr, "=> mounting /dev...");
+	if (mount("tmpfs", "/dev", "tmpfs", MS_NOSUID | MS_STRICTATIME, "mode=755,size=65536k")) {
+		fprintf(stderr, "failed: %m\n");
+		return -1;
+	}
+	umask(0);
+	if (mknod("/dev/null", S_IFCHR | 0666, makedev(1, 3))) {
+		fprintf(stderr, "mknod null failed: %m\n");
+	}
+	if (mknod("/dev/zero", S_IFCHR | 0666, makedev(1, 5))) {
+		fprintf(stderr, "mknod zero failed: %m\n");
+	}
+	if (mknod("/dev/urandom", S_IFCHR | 0666, makedev(1, 9))) {
+		fprintf(stderr, "mknod urandom failed: %m\n");
+	}
+	fprintf(stderr, "done.\n");
+
+	return 0;
+}