Systemd/src/shared/dissect-image.h
Lennart Poettering 2d3a5a73e0 nspawn: make sure images containing an ESP are compatible with userns -U mode
In -U mode we might need to re-chown() all files and directories to
match the UID shift we want for the image. That's problematic on fat
partitions, such as the ESP (and which is generated by mkosi's
--bootable switch), because fat of course knows no UID/GID file
ownership natively.

With this change we take benefit of the uid= and gid= mount options FAT
knows: instead of chown()ing all files and directories we can just
specify the right UID/GID to use at mount time.

This beefs up the image dissection logic in two ways:

1. First of all support for mounting relevant file systems with
   uid=/gid= is added: when a UID is specified during mount it is used for
   all applicable file systems.

2. Secondly, two new mount flags are added:
   DISSECT_IMAGE_MOUNT_ROOT_ONLY and DISSECT_IMAGE_MOUNT_NON_ROOT_ONLY.
   If one is specified the mount routine will either only mount the root
   partition of an image, or all partitions except the root partition.
   This is used by nspawn: first the root partition is mounted, so that
   we can determine the UID shift in use so far, based on ownership of
   the image's root directory. Then, we mount the remaining partitions
   in a second go, this time with the right UID/GID information.
2017-12-05 13:49:12 +01:00

111 lines
4.6 KiB
C

/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once
/***
This file is part of systemd.
Copyright 2016 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdbool.h>
#include "macro.h"
typedef struct DissectedImage DissectedImage;
typedef struct DissectedPartition DissectedPartition;
typedef struct DecryptedImage DecryptedImage;
struct DissectedPartition {
bool found:1;
bool rw:1;
int partno; /* -1 if there was no partition and the images contains a file system directly */
int architecture; /* Intended architecture: either native, secondary or unset (-1). */
sd_id128_t uuid; /* Partition entry UUID as reported by the GPT */
char *fstype;
char *node;
char *decrypted_node;
char *decrypted_fstype;
};
enum {
PARTITION_ROOT,
PARTITION_ROOT_SECONDARY, /* Secondary architecture */
PARTITION_HOME,
PARTITION_SRV,
PARTITION_ESP,
PARTITION_SWAP,
PARTITION_ROOT_VERITY, /* verity data for the PARTITION_ROOT partition */
PARTITION_ROOT_SECONDARY_VERITY, /* verity data for the PARTITION_ROOT_SECONDARY partition */
_PARTITION_DESIGNATOR_MAX,
_PARTITION_DESIGNATOR_INVALID = -1
};
static inline int PARTITION_VERITY_OF(int p) {
if (p == PARTITION_ROOT)
return PARTITION_ROOT_VERITY;
if (p == PARTITION_ROOT_SECONDARY)
return PARTITION_ROOT_SECONDARY_VERITY;
return _PARTITION_DESIGNATOR_INVALID;
}
typedef enum DissectImageFlags {
DISSECT_IMAGE_READ_ONLY = 1 << 0,
DISSECT_IMAGE_DISCARD_ON_LOOP = 1 << 1, /* Turn on "discard" if on a loop device and file system supports it */
DISSECT_IMAGE_DISCARD = 1 << 2, /* Turn on "discard" if file system supports it, on all block devices */
DISSECT_IMAGE_DISCARD_ON_CRYPTO = 1 << 3, /* Turn on "discard" also on crypto devices */
DISSECT_IMAGE_DISCARD_ANY = DISSECT_IMAGE_DISCARD_ON_LOOP |
DISSECT_IMAGE_DISCARD |
DISSECT_IMAGE_DISCARD_ON_CRYPTO,
DISSECT_IMAGE_GPT_ONLY = 1 << 4, /* Only recognize images with GPT partition tables */
DISSECT_IMAGE_REQUIRE_ROOT = 1 << 5, /* Don't accept disks without root partition */
DISSECT_IMAGE_MOUNT_ROOT_ONLY = 1 << 6, /* Mount only the root partition */
DISSECT_IMAGE_MOUNT_NON_ROOT_ONLY = 1 << 7, /* Mount only non-root partitions */
} DissectImageFlags;
struct DissectedImage {
bool encrypted:1;
bool verity:1; /* verity available and usable */
bool can_verity:1; /* verity available, but not necessarily used */
DissectedPartition partitions[_PARTITION_DESIGNATOR_MAX];
char *hostname;
sd_id128_t machine_id;
char **machine_info;
char **os_release;
};
int probe_filesystem(const char *node, char **ret_fstype);
int dissect_image(int fd, const void *root_hash, size_t root_hash_size, DissectImageFlags flags, DissectedImage **ret);
DissectedImage* dissected_image_unref(DissectedImage *m);
DEFINE_TRIVIAL_CLEANUP_FUNC(DissectedImage*, dissected_image_unref);
int dissected_image_decrypt(DissectedImage *m, const char *passphrase, const void *root_hash, size_t root_hash_size, DissectImageFlags flags, DecryptedImage **ret);
int dissected_image_decrypt_interactively(DissectedImage *m, const char *passphrase, const void *root_hash, size_t root_hash_size, DissectImageFlags flags, DecryptedImage **ret);
int dissected_image_mount(DissectedImage *m, const char *dest, uid_t uid_shift, DissectImageFlags flags);
int dissected_image_acquire_metadata(DissectedImage *m);
DecryptedImage* decrypted_image_unref(DecryptedImage *p);
DEFINE_TRIVIAL_CLEANUP_FUNC(DecryptedImage*, decrypted_image_unref);
int decrypted_image_relinquish(DecryptedImage *d);
const char* partition_designator_to_string(int i) _const_;
int partition_designator_from_string(const char *name) _pure_;
int root_hash_load(const char *image, void **ret, size_t *ret_size);