ac1f3ad05f
Opening a verity device is an expensive operation. The kernelspace operations are mostly sequential with a global lock held regardless of which device is being opened. In userspace jumps in and out of multiple libraries are required. When signatures are used, there's the additional cryptographic checks. We know when two devices are identical: they have the same root hash. If libcrypsetup returns EEXIST, double check that the hashes are really the same, and that either both or none have a signature, and if everything matches simply remount the already open device. The kernel will do reference counting for us. In order to quickly and reliably discover if a device is already open, change the node naming scheme from '/dev/mapper/major:minor-verity' to '/dev/mapper/$roothash-verity'. Unfortunately libdevmapper is not 100% reliable, so in some case it will say that the device already exists and it is active, but in reality it is not usable. Fallback to an individually-activated unique device name in those cases for robustness.
107 lines
5.5 KiB
C
107 lines
5.5 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#pragma once
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#include <stdbool.h>
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#include "sd-id128.h"
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#include "macro.h"
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typedef struct DissectedImage DissectedImage;
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typedef struct DissectedPartition DissectedPartition;
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typedef struct DecryptedImage DecryptedImage;
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struct DissectedPartition {
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bool found:1;
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bool rw:1;
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int partno; /* -1 if there was no partition and the images contains a file system directly */
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int architecture; /* Intended architecture: either native, secondary or unset (-1). */
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sd_id128_t uuid; /* Partition entry UUID as reported by the GPT */
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char *fstype;
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char *node;
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char *decrypted_node;
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char *decrypted_fstype;
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};
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enum {
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PARTITION_ROOT,
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PARTITION_ROOT_SECONDARY, /* Secondary architecture */
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PARTITION_HOME,
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PARTITION_SRV,
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PARTITION_ESP,
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PARTITION_XBOOTLDR,
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PARTITION_SWAP,
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PARTITION_ROOT_VERITY, /* verity data for the PARTITION_ROOT partition */
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PARTITION_ROOT_SECONDARY_VERITY, /* verity data for the PARTITION_ROOT_SECONDARY partition */
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PARTITION_TMP,
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PARTITION_VAR,
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_PARTITION_DESIGNATOR_MAX,
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_PARTITION_DESIGNATOR_INVALID = -1
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};
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static inline int PARTITION_VERITY_OF(int p) {
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if (p == PARTITION_ROOT)
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return PARTITION_ROOT_VERITY;
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if (p == PARTITION_ROOT_SECONDARY)
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return PARTITION_ROOT_SECONDARY_VERITY;
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return _PARTITION_DESIGNATOR_INVALID;
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}
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typedef enum DissectImageFlags {
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DISSECT_IMAGE_READ_ONLY = 1 << 0,
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DISSECT_IMAGE_DISCARD_ON_LOOP = 1 << 1, /* Turn on "discard" if on a loop device and file system supports it */
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DISSECT_IMAGE_DISCARD = 1 << 2, /* Turn on "discard" if file system supports it, on all block devices */
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DISSECT_IMAGE_DISCARD_ON_CRYPTO = 1 << 3, /* Turn on "discard" also on crypto devices */
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DISSECT_IMAGE_DISCARD_ANY = DISSECT_IMAGE_DISCARD_ON_LOOP |
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DISSECT_IMAGE_DISCARD |
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DISSECT_IMAGE_DISCARD_ON_CRYPTO,
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DISSECT_IMAGE_GPT_ONLY = 1 << 4, /* Only recognize images with GPT partition tables */
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DISSECT_IMAGE_REQUIRE_ROOT = 1 << 5, /* Don't accept disks without root partition */
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DISSECT_IMAGE_MOUNT_ROOT_ONLY = 1 << 6, /* Mount only the root partition */
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DISSECT_IMAGE_MOUNT_NON_ROOT_ONLY = 1 << 7, /* Mount only non-root partitions */
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DISSECT_IMAGE_VALIDATE_OS = 1 << 8, /* Refuse mounting images that aren't identifiable as OS images */
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DISSECT_IMAGE_NO_UDEV = 1 << 9, /* Don't wait for udev initializing things */
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DISSECT_IMAGE_RELAX_VAR_CHECK = 1 << 10, /* Don't insist that the UUID of /var is hashed from /etc/machine-id */
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DISSECT_IMAGE_FSCK = 1 << 11, /* File system check the partition before mounting (no effect when combined with DISSECT_IMAGE_READ_ONLY) */
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DISSECT_IMAGE_NO_PARTITION_TABLE = 1 << 12, /* Only recognize single file system images */
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DISSECT_IMAGE_VERITY_SHARE = 1 << 13, /* When activating a verity device, reuse existing one if already open */
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} DissectImageFlags;
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struct DissectedImage {
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bool encrypted:1;
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bool verity:1; /* verity available and usable */
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bool can_verity:1; /* verity available, but not necessarily used */
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bool single_file_system:1; /* MBR/GPT or single file system */
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DissectedPartition partitions[_PARTITION_DESIGNATOR_MAX];
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char *hostname;
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sd_id128_t machine_id;
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char **machine_info;
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char **os_release;
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};
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int probe_filesystem(const char *node, char **ret_fstype);
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int dissect_image(int fd, const void *root_hash, size_t root_hash_size, const char *verity_data, DissectImageFlags flags, DissectedImage **ret);
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int dissect_image_and_warn(int fd, const char *name, const void *root_hash, size_t root_hash_size, const char *verity_data, DissectImageFlags flags, DissectedImage **ret);
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DissectedImage* dissected_image_unref(DissectedImage *m);
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DEFINE_TRIVIAL_CLEANUP_FUNC(DissectedImage*, dissected_image_unref);
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int dissected_image_decrypt(DissectedImage *m, const char *passphrase, const void *root_hash, size_t root_hash_size, const char *verity_data, const char *root_hash_sig_path, const void *root_hash_sig, size_t root_hash_sig_size, DissectImageFlags flags, DecryptedImage **ret);
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int dissected_image_decrypt_interactively(DissectedImage *m, const char *passphrase, const void *root_hash, size_t root_hash_size, const char *verity_data, const char *root_hash_sig_path, const void *root_hash_sig, size_t root_hash_sig_size, DissectImageFlags flags, DecryptedImage **ret);
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int dissected_image_mount(DissectedImage *m, const char *dest, uid_t uid_shift, DissectImageFlags flags);
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int dissected_image_acquire_metadata(DissectedImage *m);
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DecryptedImage* decrypted_image_unref(DecryptedImage *p);
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DEFINE_TRIVIAL_CLEANUP_FUNC(DecryptedImage*, decrypted_image_unref);
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int decrypted_image_relinquish(DecryptedImage *d);
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const char* partition_designator_to_string(int i) _const_;
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int partition_designator_from_string(const char *name) _pure_;
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int verity_metadata_load(const char *image, const char *root_hash_path, void **ret_roothash, size_t *ret_roothash_size, char **ret_verity_data, char **ret_roothashsig);
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bool dissected_image_can_do_verity(const DissectedImage *image, unsigned partition_designator);
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bool dissected_image_has_verity(const DissectedImage *image, unsigned partition_designator);
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