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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
#include "Magic.h"
#include "common/dout.h"
#include "common/errno.h"
#define dout_subsys ceph_subsys_rbd
#undef dout_prefix
#define dout_prefix *_dout << "librbd::crypto::luks::Magic: " << __func__ \
<< ": "
namespace librbd {
namespace crypto {
namespace luks {
namespace {
constexpr uint64_t MAGIC_LENGTH = 6;
const std::string LUKS_MAGIC = "LUKS\xba\xbe";
const std::string RBD_CLONE_MAGIC = "RBDL\xba\xbe";
} // anonymous namespace
int Magic::read(ceph::bufferlist &bl, uint32_t bl_off,
uint32_t read_size, char* result) {
if (bl_off + read_size > bl.length()) {
return -EINVAL;
}
memcpy(result, bl.c_str() + bl_off, read_size);
return 0;
}
int Magic::cmp(ceph::bufferlist &bl, uint32_t bl_off,
const std::string &cmp_str) {
auto cmp_length = cmp_str.length();
if (bl_off + cmp_length > bl.length()) {
return -EINVAL;
}
if (memcmp(bl.c_str() + bl_off, cmp_str.c_str(), cmp_length)) {
return 0;
}
return 1;
}
int Magic::is_luks(ceph::bufferlist& bl) {
return cmp(bl, 0, LUKS_MAGIC);
}
int Magic::is_rbd_clone(ceph::bufferlist& bl) {
return cmp(bl, 0, RBD_CLONE_MAGIC);
}
void Magic::transform_secondary_header_magic(char* magic) {
std::swap(magic[0], magic[3]);
std::swap(magic[1], magic[2]);
}
int Magic::replace_magic(CephContext* cct, ceph::bufferlist& bl) {
const std::string *old_magic, *new_magic;
if (is_luks(bl) > 0) {
old_magic = &LUKS_MAGIC;
new_magic = &RBD_CLONE_MAGIC;
} else if (is_rbd_clone(bl) > 0) {
old_magic = &RBD_CLONE_MAGIC;
new_magic = &LUKS_MAGIC;
} else {
lderr(cct) << "invalid magic: " << dendl;
return -EILSEQ;
}
// read luks version
uint16_t version;
auto r = read(bl, MAGIC_LENGTH, sizeof(version), (char*)&version);
if (r < 0) {
lderr(cct) << "cannot read header version: " << cpp_strerror(r) << dendl;
return r;
}
boost::endian::big_to_native_inplace(version);
switch (version) {
case 1: {
// LUKS1, no secondary header
break;
}
case 2: {
// LUKS2, secondary header follows primary header
// read header size
uint64_t hdr_size;
r = read(bl, MAGIC_LENGTH + sizeof(version), sizeof(hdr_size),
(char*)&hdr_size);
if (r < 0) {
lderr(cct) << "cannot read header size: " << cpp_strerror(r) << dendl;
return r;
}
boost::endian::big_to_native_inplace(hdr_size);
if ((uint32_t)hdr_size + MAGIC_LENGTH > bl.length()) {
ldout(cct, 20) << "cannot replace secondary header magic" << dendl;
return -EINVAL;
}
// check secondary header magic
auto secondary_header_magic = bl.c_str() + hdr_size;
transform_secondary_header_magic(secondary_header_magic);
auto is_secondary_header_magic_valid =
!memcmp(secondary_header_magic, old_magic->c_str(), MAGIC_LENGTH);
if (!is_secondary_header_magic_valid) {
transform_secondary_header_magic(secondary_header_magic);
lderr(cct) << "invalid secondary header magic" << dendl;
return -EILSEQ;
}
// replace secondary header magic
memcpy(secondary_header_magic, new_magic->c_str(), MAGIC_LENGTH);
transform_secondary_header_magic(secondary_header_magic);
break;
}
default: {
lderr(cct) << "bad header version: " << version << dendl;
return -EINVAL;
}
}
// switch primary header magic
memcpy(bl.c_str(), new_magic->c_str(), MAGIC_LENGTH);
return 0;
}
} // namespace luks
} // namespace crypto
} // namespace librbd
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