diff options
Diffstat (limited to 'src/cryptenroll/cryptenroll-wipe.c')
| -rw-r--r-- | src/cryptenroll/cryptenroll-wipe.c | 445 |
1 files changed, 445 insertions, 0 deletions
diff --git a/src/cryptenroll/cryptenroll-wipe.c b/src/cryptenroll/cryptenroll-wipe.c new file mode 100644 index 0000000..314ebd3 --- /dev/null +++ b/src/cryptenroll/cryptenroll-wipe.c @@ -0,0 +1,445 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include "cryptenroll-wipe.h" +#include "cryptenroll.h" +#include "json.h" +#include "memory-util.h" +#include "parse-util.h" +#include "set.h" +#include "sort-util.h" + +static int find_all_slots(struct crypt_device *cd, Set *wipe_slots, Set *keep_slots) { + int slot_max; + + assert(cd); + assert(wipe_slots); + assert_se((slot_max = crypt_keyslot_max(CRYPT_LUKS2)) > 0); + + /* Finds all currently assigned slots, and adds them to 'wipe_slots', except if listed already in 'keep_slots' */ + + for (int slot = 0; slot < slot_max; slot++) { + crypt_keyslot_info status; + + /* No need to check this slot if we already know we want to wipe it or definitely keep it. */ + if (set_contains(keep_slots, INT_TO_PTR(slot)) || + set_contains(wipe_slots, INT_TO_PTR(slot))) + continue; + + status = crypt_keyslot_status(cd, slot); + if (!IN_SET(status, CRYPT_SLOT_ACTIVE, CRYPT_SLOT_ACTIVE_LAST)) + continue; + + if (set_put(wipe_slots, INT_TO_PTR(slot)) < 0) + return log_oom(); + } + + return 0; +} + +static int find_empty_passphrase_slots(struct crypt_device *cd, Set *wipe_slots, Set *keep_slots) { + size_t vks; + int r, slot_max; + + assert(cd); + assert(wipe_slots); + assert_se((slot_max = crypt_keyslot_max(CRYPT_LUKS2)) > 0); + + /* Finds all slots with an empty passphrase assigned (i.e. "") and adds them to 'wipe_slots', except + * if listed already in 'keep_slots' */ + + r = crypt_get_volume_key_size(cd); + if (r <= 0) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to determine LUKS volume key size"); + vks = (size_t) r; + + for (int slot = 0; slot < slot_max; slot++) { + _cleanup_(erase_and_freep) char *vk = NULL; + crypt_keyslot_info status; + + /* No need to check this slot if we already know we want to wipe it or definitely keep it. */ + if (set_contains(keep_slots, INT_TO_PTR(slot)) || + set_contains(wipe_slots, INT_TO_PTR(slot))) + continue; + + status = crypt_keyslot_status(cd, slot); + if (!IN_SET(status, CRYPT_SLOT_ACTIVE, CRYPT_SLOT_ACTIVE_LAST)) + continue; + + vk = malloc(vks); + if (!vk) + return log_oom(); + + r = crypt_volume_key_get(cd, slot, vk, &vks, "", 0); + if (r < 0) { + log_debug_errno(r, "Failed to acquire volume key from slot %i with empty password, ignoring: %m", slot); + continue; + } + + if (set_put(wipe_slots, INT_TO_PTR(r)) < 0) + return log_oom(); + } + + return 0; +} + +static int find_slots_by_mask( + struct crypt_device *cd, + Set *wipe_slots, + Set *keep_slots, + unsigned by_mask) { + + _cleanup_set_free_ Set *listed_slots = NULL; + int r; + + assert(cd); + assert(wipe_slots); + + if (by_mask == 0) + return 0; + + /* Find all slots that are associated with a token of a type in the specified token type mask */ + + for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token++) { + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + JsonVariant *w, *z; + EnrollType t; + + r = cryptsetup_get_token_as_json(cd, token, NULL, &v); + if (IN_SET(r, -ENOENT, -EINVAL)) + continue; + if (r < 0) { + log_warning_errno(r, "Failed to read JSON token data off disk, ignoring: %m"); + continue; + } + + w = json_variant_by_key(v, "type"); + if (!w || !json_variant_is_string(w)) { + log_warning("Token JSON data lacks type field, ignoring."); + continue; + } + + t = luks2_token_type_from_string(json_variant_string(w)); + + w = json_variant_by_key(v, "keyslots"); + if (!w || !json_variant_is_array(w)) { + log_warning("Token JSON data lacks keyslots field, ignoring."); + continue; + } + + JSON_VARIANT_ARRAY_FOREACH(z, w) { + int slot; + + if (!json_variant_is_string(z)) { + log_warning("Token JSON data's keyslot field is not an array of strings, ignoring."); + continue; + } + + r = safe_atoi(json_variant_string(z), &slot); + if (r < 0) { + log_warning_errno(r, "Token JSON data's keyslot filed is not an integer formatted as string, ignoring."); + continue; + } + + if (t >= 0 && (by_mask & (1U << t)) != 0) { + /* Selected by token type */ + if (set_put(wipe_slots, INT_TO_PTR(slot)) < 0) + return log_oom(); + } else if ((by_mask & (1U << ENROLL_PASSWORD)) != 0) { + /* If we shall remove all plain password slots, let's maintain a list of + * slots that are listed in any tokens, since those are *NOT* plain + * passwords */ + if (set_ensure_allocated(&listed_slots, NULL) < 0) + return log_oom(); + + if (set_put(listed_slots, INT_TO_PTR(slot)) < 0) + return log_oom(); + } + } + } + + /* "password" slots are those which have no token assigned. If we shall remove those, iterate through + * all slots and mark those for wiping that weren't listed in any token */ + if ((by_mask & (1U << ENROLL_PASSWORD)) != 0) { + int slot_max; + + assert_se((slot_max = crypt_keyslot_max(CRYPT_LUKS2)) > 0); + + for (int slot = 0; slot < slot_max; slot++) { + crypt_keyslot_info status; + + /* No need to check this slot if we already know we want to wipe it or definitely keep it. */ + if (set_contains(keep_slots, INT_TO_PTR(slot)) || + set_contains(wipe_slots, INT_TO_PTR(slot))) + continue; + + if (set_contains(listed_slots, INT_TO_PTR(slot))) /* This has a token, hence is not a password. */ + continue; + + status = crypt_keyslot_status(cd, slot); + if (!IN_SET(status, CRYPT_SLOT_ACTIVE, CRYPT_SLOT_ACTIVE_LAST)) /* Not actually assigned? */ + continue; + + /* Finally, we found a password, add it to the list of slots to wipe */ + if (set_put(wipe_slots, INT_TO_PTR(slot)) < 0) + return log_oom(); + } + } + + return 0; +} + +static int find_slot_tokens(struct crypt_device *cd, Set *wipe_slots, Set *keep_slots, Set *wipe_tokens) { + int r; + + assert(cd); + assert(wipe_slots); + assert(keep_slots); + assert(wipe_tokens); + + /* Find all tokens matching the slots we want to wipe, so that we can wipe them too. Also, for update + * the slots sets according to the token data: add any other slots listed in the tokens we act on. */ + + for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token++) { + _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; + bool shall_wipe = false; + JsonVariant *w, *z; + + r = cryptsetup_get_token_as_json(cd, token, NULL, &v); + if (IN_SET(r, -ENOENT, -EINVAL)) + continue; + if (r < 0) { + log_warning_errno(r, "Failed to read JSON token data off disk, ignoring: %m"); + continue; + } + + w = json_variant_by_key(v, "keyslots"); + if (!w || !json_variant_is_array(w)) { + log_warning("Token JSON data lacks keyslots field, ignoring."); + continue; + } + + /* Go through the slots associated with this token: if we shall keep any slot of them, the token shall stay too. */ + JSON_VARIANT_ARRAY_FOREACH(z, w) { + int slot; + + if (!json_variant_is_string(z)) { + log_warning("Token JSON data's keyslot field is not an array of strings, ignoring."); + continue; + } + + r = safe_atoi(json_variant_string(z), &slot); + if (r < 0) { + log_warning_errno(r, "Token JSON data's keyslot filed is not an integer formatted as string, ignoring."); + continue; + } + + if (set_contains(keep_slots, INT_TO_PTR(slot))) { + shall_wipe = false; + break; /* If we shall keep this slot, then this is definite: we will keep its token too */ + } + + /* If there's a slot associated with this token that we shall wipe, then remove the + * token too. But we are careful here: let's continue iterating, maybe there's a slot + * that we need to keep, in which case we can reverse the decision again. */ + if (set_contains(wipe_slots, INT_TO_PTR(slot))) + shall_wipe = true; + } + + /* Go through the slots again, and this time add them to the list of slots to keep/remove */ + JSON_VARIANT_ARRAY_FOREACH(z, w) { + int slot; + + if (!json_variant_is_string(z)) + continue; + if (safe_atoi(json_variant_string(z), &slot) < 0) + continue; + + if (set_put(shall_wipe ? wipe_slots : keep_slots, INT_TO_PTR(slot)) < 0) + return log_oom(); + } + + /* And of course, also remember the tokens to remove. */ + if (shall_wipe) + if (set_put(wipe_tokens, INT_TO_PTR(token)) < 0) + return log_oom(); + } + + return 0; +} + +static bool slots_remain(struct crypt_device *cd, Set *wipe_slots, Set *keep_slots) { + int slot_max; + + assert(cd); + assert_se((slot_max = crypt_keyslot_max(CRYPT_LUKS2)) > 0); + + /* Checks if any slots remaining in the LUKS2 header if we remove all slots listed in 'wipe_slots' + * (keeping those listed in 'keep_slots') */ + + for (int slot = 0; slot < slot_max; slot++) { + crypt_keyslot_info status; + + status = crypt_keyslot_status(cd, slot); + if (!IN_SET(status, CRYPT_SLOT_ACTIVE, CRYPT_SLOT_ACTIVE_LAST)) + continue; + + /* The "keep" set wins if a slot is listed in both sets. This is important so that we can + * safely add a new slot and remove all others of the same type, which in a naive + * implementation might mean we remove what we just added — which we of course don't want. */ + if (set_contains(keep_slots, INT_TO_PTR(slot)) || + !set_contains(wipe_slots, INT_TO_PTR(slot))) + return true; + } + + return false; +} + +int wipe_slots(struct crypt_device *cd, + const int explicit_slots[], + size_t n_explicit_slots, + WipeScope by_scope, + unsigned by_mask, + int except_slot) { + + _cleanup_set_free_ Set *wipe_slots = NULL, *wipe_tokens = NULL, *keep_slots = NULL; + _cleanup_free_ int *ordered_slots = NULL, *ordered_tokens = NULL; + size_t n_ordered_slots = 0, n_ordered_tokens = 0; + int r, slot_max, ret; + void *e; + + assert_se(cd); + + /* Shortcut if nothing to wipe. */ + if (n_explicit_slots == 0 && by_mask == 0 && by_scope == WIPE_EXPLICIT) + return 0; + + /* So this is a bit more complicated than I'd wish, but we want support three different axis for wiping slots: + * + * 1. Wiping by slot indexes + * 2. Wiping slots of specified token types + * 3. Wiping "all" entries, or entries with an empty password (i.e. "") + * + * (or any combination of the above) + * + * Plus: We always want to remove tokens matching the slots. + * Plus: We always want to exclude the slots/tokens we just added. + */ + + wipe_slots = set_new(NULL); + keep_slots = set_new(NULL); + wipe_tokens = set_new(NULL); + if (!wipe_slots || !keep_slots || !wipe_tokens) + return log_oom(); + + /* Let's maintain one set of slots for the slots we definitely want to keep */ + if (except_slot >= 0) + if (set_put(keep_slots, INT_TO_PTR(except_slot)) < 0) + return log_oom(); + + assert_se((slot_max = crypt_keyslot_max(CRYPT_LUKS2)) > 0); + + /* Maintain another set of the slots we intend to wipe */ + for (size_t i = 0; i < n_explicit_slots; i++) { + if (explicit_slots[i] >= slot_max) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Slot index %i out of range.", explicit_slots[i]); + + if (set_put(wipe_slots, INT_TO_PTR(explicit_slots[i])) < 0) + return log_oom(); + } + + /* Now, handle the "all" and "empty passphrase" cases. */ + switch (by_scope) { + + case WIPE_EXPLICIT: + break; /* Nothing to do here */ + + case WIPE_ALL: + r = find_all_slots(cd, wipe_slots, keep_slots); + if (r < 0) + return r; + + break; + + case WIPE_EMPTY_PASSPHRASE: + r = find_empty_passphrase_slots(cd, wipe_slots, keep_slots); + if (r < 0) + return r; + + break; + default: + assert_not_reached(); + } + + /* Then add all slots that match a token type */ + r = find_slots_by_mask(cd, wipe_slots, keep_slots, by_mask); + if (r < 0) + return r; + + /* And determine tokens that we shall remove */ + r = find_slot_tokens(cd, wipe_slots, keep_slots, wipe_tokens); + if (r < 0) + return r; + + /* Safety check: let's make sure that after we are done there's at least one slot remaining */ + if (!slots_remain(cd, wipe_slots, keep_slots)) + return log_error_errno(SYNTHETIC_ERRNO(EPERM), + "Wipe operation would leave no valid slots around, can't allow that, sorry."); + + /* Generated ordered lists of the slots and the tokens to remove */ + ordered_slots = new(int, set_size(wipe_slots)); + if (!ordered_slots) + return log_oom(); + SET_FOREACH(e, wipe_slots) { + int slot = PTR_TO_INT(e); + + if (set_contains(keep_slots, INT_TO_PTR(slot))) + continue; + + ordered_slots[n_ordered_slots++] = slot; + } + typesafe_qsort(ordered_slots, n_ordered_slots, cmp_int); + + ordered_tokens = new(int, set_size(wipe_tokens)); + if (!ordered_tokens) + return log_oom(); + SET_FOREACH(e, wipe_tokens) + ordered_tokens[n_ordered_tokens++] = PTR_TO_INT(e); + typesafe_qsort(ordered_tokens, n_ordered_tokens, cmp_int); + + if (n_ordered_slots == 0 && n_ordered_tokens == 0) { + log_full(except_slot < 0 ? LOG_NOTICE : LOG_DEBUG, + "No slots to remove selected."); + return 0; + } + + if (DEBUG_LOGGING) { + for (size_t i = 0; i < n_ordered_slots; i++) + log_debug("Going to wipe slot %i.", ordered_slots[i]); + for (size_t i = 0; i < n_ordered_tokens; i++) + log_debug("Going to wipe token %i.", ordered_tokens[i]); + } + + /* Now, let's actually start wiping things. (We go from back to front, to make space at the end + * first.) */ + ret = 0; + for (size_t i = n_ordered_slots; i > 0; i--) { + r = crypt_keyslot_destroy(cd, ordered_slots[i - 1]); + if (r < 0) { + log_warning_errno(r, "Failed to wipe slot %i, continuing: %m", ordered_slots[i - 1]); + if (ret == 0) + ret = r; + } else + log_info("Wiped slot %i.", ordered_slots[i - 1]); + } + + for (size_t i = n_ordered_tokens; i > 0; i--) { + r = crypt_token_json_set(cd, ordered_tokens[i - 1], NULL); + if (r < 0) { + log_warning_errno(r, "Failed to wipe token %i, continuing: %m", ordered_tokens[i - 1]); + if (ret == 0) + ret = r; + } + } + + return ret; +} |