init: remove TEE-specific code

init/fs.c

@@ -0,0 +1,169 @@
+#include "fs.h"
+
+static int try_mount(const char *source, const char *target, const char *fstype,
+              unsigned long mountflags, const void *data);
+
+void setup_root_block_device(void)
+{
+    int fd;
+    char *krun_root;
+    char *krun_root_fstype;
+    char *krun_root_options;
+
+    krun_root = getenv("KRUN_BLOCK_ROOT_DEVICE");
+    if (krun_root) {
+        if (mkdir("/newroot", 0755) < 0 && errno != EEXIST) {
+            perror("mkdir(/newroot)");
+            exit(-1);
+        }
+
+        krun_root_fstype = getenv("KRUN_BLOCK_ROOT_FSTYPE");
+        krun_root_options = getenv("KRUN_BLOCK_ROOT_OPTIONS");
+
+        if (try_mount(krun_root, "/newroot", krun_root_fstype, 0,
+                      krun_root_options) < 0) {
+            perror("mount KRUN_BLOCK_ROOT_DEVICE");
+            exit(-1);
+        }
+
+        chdir("/newroot");
+
+        fd = open("/", O_RDONLY);
+        if (fd < 0) {
+            perror("Couldn't open temporary root directory for removing");
+            exit(-1);
+        }
+        if (ioctl(fd, KRUN_REMOVE_ROOT_DIR_IOCTL) < 0) {
+            perror("Error removing temporary root directory");
+        }
+        close(fd);
+
+        if (mount(".", "/", NULL, MS_MOVE, NULL) < 0) {
+            perror("remount root");
+            exit(-1);
+        }
+        chroot(".");
+
+        // we must mount filesystems again after chrooting
+        if (mount_filesystems() < 0) {
+            printf("Couldn't mount filesystems, bailing out\n");
+            exit(-2);
+        }
+    }
+
+    if (mount(NULL, "/", NULL, MS_REC | MS_SHARED, NULL) < 0) {
+        perror("Couldn't set shared propagation on the root mount");
+        exit(-1);
+    }
+}
+
+int mount_filesystems()
+{
+    char *const DIRS_LEVEL1[] = {"/dev", "/proc", "/sys"};
+    char *const DIRS_LEVEL2[] = {"/dev/pts", "/dev/shm"};
+    int i;
+
+    for (i = 0; i < 3; ++i) {
+        if (mkdir(DIRS_LEVEL1[i], 0755) < 0 && errno != EEXIST) {
+            printf("Error creating directory (%s)\n", DIRS_LEVEL1[i]);
+            return -1;
+        }
+    }
+
+    if (mount("devtmpfs", "/dev", "devtmpfs", MS_RELATIME, NULL) < 0 &&
+        errno != EBUSY) {
+        perror("mount(/dev)");
+        return -1;
+    }
+
+    if (mount("proc", "/proc", "proc",
+              MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RELATIME, NULL) < 0) {
+        perror("mount(/proc)");
+        return -1;
+    }
+
+    if (mount("sysfs", "/sys", "sysfs",
+              MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RELATIME, NULL) < 0) {
+        perror("mount(/sys)");
+        return -1;
+    }
+
+    if (mount("cgroup2", "/sys/fs/cgroup", "cgroup2",
+              MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RELATIME, NULL) < 0) {
+        perror("mount(/sys/fs/cgroup)");
+        return -1;
+    }
+
+    for (i = 0; i < 2; ++i) {
+        if (mkdir(DIRS_LEVEL2[i], 0755) < 0 && errno != EEXIST) {
+            printf("Error creating directory (%s)\n", DIRS_LEVEL2[i]);
+            return -1;
+        }
+    }
+
+    if (mount("devpts", "/dev/pts", "devpts",
+              MS_NOEXEC | MS_NOSUID | MS_RELATIME, NULL) < 0) {
+        perror("mount(/dev/pts)");
+        return -1;
+    }
+
+    if (mount("tmpfs", "/dev/shm", "tmpfs", MS_NOEXEC | MS_NOSUID | MS_RELATIME,
+              NULL) < 0) {
+        perror("mount(/dev/shm)");
+        return -1;
+    }
+
+    /* May fail if already exists and that's fine. */
+    symlink("/proc/self/fd", "/dev/fd");
+
+    return 0;
+}
+
+static int try_mount(const char *source, const char *target, const char *fstype,
+              unsigned long mountflags, const void *data)
+{
+    FILE *f;
+    char line[129];
+    int mount_status = -1;
+
+    if (fstype) {
+        return mount(source, target, fstype, mountflags, data);
+    }
+
+    f = fopen("/proc/filesystems", "r");
+    if (f == NULL) {
+        perror("fopen(/proc/filesystems)");
+        return -1;
+    }
+    while (fgets(line, sizeof(line), f)) {
+        char fstype[sizeof(line)];
+        if (!strncmp(line, "nodev", 5)) {
+            continue;
+        }
+        if (sscanf(line, "%128s\n", fstype) != 1) {
+            continue;
+        }
+
+        mount_status = mount(source, target, fstype, mountflags, data);
+        if (mount_status == 0) {
+            break;
+        }
+    }
+    fclose(f);
+
+    return mount_status;
+}
+
+int is_virtiofs(const char *path)
+{
+    struct statfs fs;
+
+    if (statfs(path, &fs) != 0) {
+        perror("statfs");
+        return -1;
+    }
+
+    // virtiofs magic number: 0x65735546
+    return (fs.f_type == 0x65735546) ? 1 : 0;
+}
+

init/fs.h

@@ -0,0 +1,21 @@
+#ifndef FS_H
+#define FS_H
+
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+
+#define KRUN_REMOVE_ROOT_DIR_IOCTL 0x7603
+
+void setup_root_block_device(void);
+int is_virtiofs(const char *path);
+int mount_filesystems();
+
+#endif