git-crypt/commands.cpp at master · adamluzsi-backup/git-crypt · GitHub

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* This file is part of git-crypt.

* git-crypt is free software: you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation, either version 3 of the License, or

* (at your option) any later version.

* git-crypt 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 General Public License for more details.

* You should have received a copy of the GNU General Public License

* along with git-crypt. If not, see <http://www.gnu.org/licenses/>.

* Additional permission under GNU GPL version 3 section 7:

* If you modify the Program, or any covered work, by linking or

* combining it with the OpenSSL project's OpenSSL library (or a

* modified version of that library), containing parts covered by the

* terms of the OpenSSL or SSLeay licenses, the licensors of the Program

* grant you additional permission to convey the resulting work.

* Corresponding Source for a non-source form of such a combination

* shall include the source code for the parts of OpenSSL used as well

* as that of the covered work.

#include "commands.hpp"

#include "crypto.hpp"

#include "util.hpp"

#include "key.hpp"

#include "gpg.hpp"

#include "parse_options.hpp"

#include "coprocess.hpp"

#include <unistd.h>

#include <stdint.h>

#include <algorithm>

#include <string>

#include <fstream>

#include <sstream>

#include <iostream>

#include <cstddef>

#include <cstring>

#include <cctype>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <exception>

#include <vector>

enum {

// # of arguments per git checkout call; must be large enough to be efficient but small

// enough to avoid operating system limits on argument length

GIT_CHECKOUT_BATCH_SIZE = 100

};

static std::string attribute_name (const char* key_name)

{

if (key_name) {

// named key

return std::string("git-crypt-") + key_name;

} else {

// default key

return "git-crypt";

}

static std::string git_version_string ()

{

std::vector<std::string> command;

command.push_back("git");

command.push_back("version");

std::stringstream output;

if (!successful_exit(exec_command(command, output))) {

throw Error("'git version' failed - is Git installed?");

}

std::string word;

output >> word; // "git"

output >> word; // "version"

output >> word; // "1.7.10.4"

return word;

}

static std::vector<int> parse_version (const std::string& str)

{

std::istringstream in(str);

std::vector<int> version;

std::string component;

while (std::getline(in, component, '.')) {

version.push_back(std::atoi(component.c_str()));

}

return version;

}

static const std::vector<int>& git_version ()

{

static const std::vector<int> version(parse_version(git_version_string()));

return version;

}

static std::vector<int> make_version (int a, int b, int c)

{

std::vector<int> version;

version.push_back(a);

version.push_back(b);

version.push_back(c);

return version;

}

static void git_config (const std::string& name, const std::string& value)

{

std::vector<std::string> command;

command.push_back("git");

command.push_back("config");

command.push_back(name);

command.push_back(value);

if (!successful_exit(exec_command(command))) {

throw Error("'git config' failed");

}

static bool git_has_config (const std::string& name)

{

std::vector<std::string> command;

command.push_back("git");

command.push_back("config");

command.push_back("--get-all");

command.push_back(name);

std::stringstream output;

switch (exit_status(exec_command(command, output))) {

case 0: return true;

case 1: return false;

default: throw Error("'git config' failed");

}

static void git_deconfig (const std::string& name)

{

std::vector<std::string> command;

command.push_back("git");

command.push_back("config");

command.push_back("--remove-section");

command.push_back(name);

if (!successful_exit(exec_command(command))) {

throw Error("'git config' failed");

}

static void configure_git_filters (const char* key_name)

{

std::string escaped_git_crypt_path(escape_shell_arg(our_exe_path()));

if (key_name) {

// Note: key_name contains only shell-safe characters so it need not be escaped.

git_config(std::string("filter.git-crypt-") + key_name + ".smudge",

escaped_git_crypt_path + " smudge --key-name=" + key_name);

git_config(std::string("filter.git-crypt-") + key_name + ".clean",

escaped_git_crypt_path + " clean --key-name=" + key_name);

git_config(std::string("filter.git-crypt-") + key_name + ".required", "true");

git_config(std::string("diff.git-crypt-") + key_name + ".textconv",

escaped_git_crypt_path + " diff --key-name=" + key_name);

} else {

git_config("filter.git-crypt.smudge", escaped_git_crypt_path + " smudge");

git_config("filter.git-crypt.clean", escaped_git_crypt_path + " clean");

git_config("filter.git-crypt.required", "true");

git_config("diff.git-crypt.textconv", escaped_git_crypt_path + " diff");

}

static void deconfigure_git_filters (const char* key_name)

{

// deconfigure the git-crypt filters

if (git_has_config("filter." + attribute_name(key_name) + ".smudge") ||

git_has_config("filter." + attribute_name(key_name) + ".clean") ||

git_has_config("filter." + attribute_name(key_name) + ".required")) {

git_deconfig("filter." + attribute_name(key_name));

}

if (git_has_config("diff." + attribute_name(key_name) + ".textconv")) {

git_deconfig("diff." + attribute_name(key_name));

}

static bool git_checkout_batch (std::vector<std::string>::const_iterator paths_begin, std::vector<std::string>::const_iterator paths_end)

{

if (paths_begin == paths_end) {

return true;

}

std::vector<std::string> command;

command.push_back("git");

command.push_back("checkout");

command.push_back("--");

for (auto path(paths_begin); path != paths_end; ++path) {

command.push_back(*path);

}

if (!successful_exit(exec_command(command))) {

return false;

}

return true;

}

static bool git_checkout (const std::vector<std::string>& paths)

{

auto paths_begin(paths.begin());

while (paths.end() - paths_begin >= GIT_CHECKOUT_BATCH_SIZE) {

if (!git_checkout_batch(paths_begin, paths_begin + GIT_CHECKOUT_BATCH_SIZE)) {

return false;

}

paths_begin += GIT_CHECKOUT_BATCH_SIZE;

}

return git_checkout_batch(paths_begin, paths.end());

}

static bool same_key_name (const char* a, const char* b)

{

return (!a && !b) || (a && b && std::strcmp(a, b) == 0);

}

static void validate_key_name_or_throw (const char* key_name)

{

std::string reason;

if (!validate_key_name(key_name, &reason)) {

throw Error(reason);

}

static std::string get_internal_state_path ()

{

// git rev-parse --git-dir

std::vector<std::string> command;

command.push_back("git");

command.push_back("rev-parse");

command.push_back("--git-dir");

std::stringstream output;

if (!successful_exit(exec_command(command, output))) {

throw Error("'git rev-parse --git-dir' failed - is this a Git repository?");

}

std::string path;

std::getline(output, path);

path += "/git-crypt";

return path;

}

static std::string get_internal_keys_path (const std::string& internal_state_path)

{

return internal_state_path + "/keys";

}

static std::string get_internal_keys_path ()

{

return get_internal_keys_path(get_internal_state_path());

}

static std::string get_internal_key_path (const char* key_name)

{

std::string path(get_internal_keys_path());

path += "/";

path += key_name ? key_name : "default";

return path;

}

std::string get_git_config (const std::string& name)

{

// git config --get

std::vector<std::string> command;

command.push_back("git");

command.push_back("config");

command.push_back("--get");

command.push_back(name);

std::stringstream output;

if (!successful_exit(exec_command(command, output))) {

throw Error("'git config' missing value for key '" + name +"'");

}

std::string value;

std::getline(output, value);

return value;

}

static std::string get_repo_state_path ()

{

// git rev-parse --show-toplevel

std::vector<std::string> command;

command.push_back("git");

command.push_back("rev-parse");

command.push_back("--show-toplevel");

std::stringstream output;

if (!successful_exit(exec_command(command, output))) {

throw Error("'git rev-parse --show-toplevel' failed - is this a Git repository?");

}

std::string path;

std::getline(output, path);

if (path.empty()) {

// could happen for a bare repo

throw Error("Could not determine Git working tree - is this a non-bare repo?");

}

// Check if the repo state dir has been explicitly configured. If so, use that in path construction.

if (git_has_config("git-crypt.repoStateDir")) {

std::string repoStateDir = get_git_config("git-crypt.repoStateDir");

// The repoStateDir value must always be relative to git work tree to ensure the repoStateDir can be committed

// along with the remainder of the repository.

path += '/' + repoStateDir;

} else {

// There is no explicitly configured repo state dir configured, so use the default.

path += "/.git-crypt";

}

return path;

}

static std::string get_repo_keys_path (const std::string& repo_state_path)

{

return repo_state_path + "/keys";

}

static std::string get_repo_keys_path ()

{

return get_repo_keys_path(get_repo_state_path());

}

static std::string get_path_to_top ()

{

// git rev-parse --show-cdup

std::vector<std::string> command;

command.push_back("git");

command.push_back("rev-parse");

command.push_back("--show-cdup");

std::stringstream output;

if (!successful_exit(exec_command(command, output))) {

throw Error("'git rev-parse --show-cdup' failed - is this a Git repository?");

}

std::string path_to_top;

std::getline(output, path_to_top);

return path_to_top;

}

static void get_git_status (std::ostream& output)

{

// git status -uno --porcelain

std::vector<std::string> command;

command.push_back("git");

command.push_back("status");

command.push_back("-uno"); // don't show untracked files

command.push_back("--porcelain");

if (!successful_exit(exec_command(command, output))) {

throw Error("'git status' failed - is this a Git repository?");

}

// returns filter and diff attributes as a pair

static std::pair<std::string, std::string> get_file_attributes (const std::string& filename)

{

// git check-attr filter diff -- filename

std::vector<std::string> command;

command.push_back("git");

command.push_back("check-attr");

command.push_back("filter");

command.push_back("diff");

command.push_back("--");

command.push_back(filename);

std::stringstream output;

if (!successful_exit(exec_command(command, output))) {

throw Error("'git check-attr' failed - is this a Git repository?");

}

std::string filter_attr;

std::string diff_attr;

std::string line;

// Example output:

// filename: filter: git-crypt

// filename: diff: git-crypt

while (std::getline(output, line)) {

// filename might contain ": ", so parse line backwards

// filename: attr_name: attr_value

// ^name_pos ^value_pos

const std::string::size_type value_pos(line.rfind(": "));

if (value_pos == std::string::npos || value_pos == 0) {

continue;

}

const std::string::size_type name_pos(line.rfind(": ", value_pos - 1));

if (name_pos == std::string::npos) {

continue;

}

const std::string attr_name(line.substr(name_pos + 2, value_pos - (name_pos + 2)));

const std::string attr_value(line.substr(value_pos + 2));

if (attr_value != "unspecified" && attr_value != "unset" && attr_value != "set") {

if (attr_name == "filter") {

filter_attr = attr_value;

} else if (attr_name == "diff") {

diff_attr = attr_value;

}

return std::make_pair(filter_attr, diff_attr);

}

// returns filter and diff attributes as a pair

static std::pair<std::string, std::string> get_file_attributes (const std::string& filename, std::ostream& check_attr_stdin, std::istream& check_attr_stdout)

{

check_attr_stdin << filename << '\0' << std::flush;

std::string filter_attr;

std::string diff_attr;

// Example output:

// filename\0filter\0git-crypt\0filename\0diff\0git-crypt\0

for (int i = 0; i < 2; ++i) {

std::string filename;

std::string attr_name;

std::string attr_value;

std::getline(check_attr_stdout, filename, '\0');

std::getline(check_attr_stdout, attr_name, '\0');

std::getline(check_attr_stdout, attr_value, '\0');

if (attr_value != "unspecified" && attr_value != "unset" && attr_value != "set") {

if (attr_name == "filter") {

filter_attr = attr_value;

} else if (attr_name == "diff") {

diff_attr = attr_value;

}

return std::make_pair(filter_attr, diff_attr);

}

static bool check_if_blob_is_encrypted (const std::string& object_id)

{

// git cat-file blob object_id

std::vector<std::string> command;

command.push_back("git");

command.push_back("cat-file");

command.push_back("blob");

command.push_back(object_id);

// TODO: do this more efficiently - don't read entire command output into buffer, only read what we need

std::stringstream output;

if (!successful_exit(exec_command(command, output))) {

throw Error("'git cat-file' failed - is this a Git repository?");

}

char header[10];

output.read(header, sizeof(header));

return output.gcount() == sizeof(header) && std::memcmp(header, "\0GITCRYPT\0", 10) == 0;

}

static bool check_if_file_is_encrypted (const std::string& filename)

{

// git ls-files -sz filename

std::vector<std::string> command;

command.push_back("git");

command.push_back("ls-files");

command.push_back("-sz");

command.push_back("--");

command.push_back(filename);

std::stringstream output;

if (!successful_exit(exec_command(command, output))) {

throw Error("'git ls-files' failed - is this a Git repository?");

}

if (output.peek() == -1) {

return false;

}

std::string mode;

std::string object_id;

output >> mode >> object_id;

return check_if_blob_is_encrypted(object_id);

}

static bool is_git_file_mode (const std::string& mode)

{

return (std::strtoul(mode.c_str(), nullptr, 8) & 0170000) == 0100000;

}

static void get_encrypted_files (std::vector<std::string>& files, const char* key_name)

{

// git ls-files -cz -- path_to_top

std::vector<std::string> ls_files_command;

ls_files_command.push_back("git");

ls_files_command.push_back("ls-files");

ls_files_command.push_back("-csz");

ls_files_command.push_back("--");

const std::string path_to_top(get_path_to_top());

if (!path_to_top.empty()) {

ls_files_command.push_back(path_to_top);

}

Coprocess ls_files;

std::istream* ls_files_stdout = ls_files.stdout_pipe();

ls_files.spawn(ls_files_command);

Coprocess check_attr;

std::ostream* check_attr_stdin = nullptr;

std::istream* check_attr_stdout = nullptr;

if (git_version() >= make_version(1, 8, 5)) {

// In Git 1.8.5 (released 27 Nov 2013) and higher, we use a single `git check-attr` process

// to get the attributes of all files at once. In prior versions, we have to fork and exec

// a separate `git check-attr` process for each file, since -z and --stdin aren't supported.

// In a repository with thousands of files, this results in an almost 100x speedup.

std::vector<std::string> check_attr_command;

check_attr_command.push_back("git");

check_attr_command.push_back("check-attr");

check_attr_command.push_back("--stdin");

check_attr_command.push_back("-z");

check_attr_command.push_back("filter");

check_attr_command.push_back("diff");

check_attr_stdin = check_attr.stdin_pipe();

check_attr_stdout = check_attr.stdout_pipe();

check_attr.spawn(check_attr_command);

}

while (ls_files_stdout->peek() != -1) {

std::string mode;

std::string object_id;

std::string stage;

std::string filename;

*ls_files_stdout >> mode >> object_id >> stage >> std::ws;

std::getline(*ls_files_stdout, filename, '\0');

if (is_git_file_mode(mode)) {

std::string filter_attribute;

if (check_attr_stdin) {

filter_attribute = get_file_attributes(filename, *check_attr_stdin, *check_attr_stdout).first;

} else {

filter_attribute = get_file_attributes(filename).first;

}

if (filter_attribute == attribute_name(key_name)) {

files.push_back(filename);

}

if (!successful_exit(ls_files.wait())) {

throw Error("'git ls-files' failed - is this a Git repository?");

}

if (check_attr_stdin) {

check_attr.close_stdin();

if (!successful_exit(check_attr.wait())) {

throw Error("'git check-attr' failed - is this a Git repository?");

}

static void load_key (Key_file& key_file, const char* key_name, const char* key_path =0, const char* legacy_path =0)

{

if (legacy_path) {

std::ifstream key_file_in(legacy_path, std::fstream::binary);

if (!key_file_in) {

throw Error(std::string("Unable to open key file: ") + legacy_path);

}

key_file.load_legacy(key_file_in);

} else if (key_path) {

std::ifstream key_file_in(key_path, std::fstream::binary);

if (!key_file_in) {

throw Error(std::string("Unable to open key file: ") + key_path);

}

key_file.load(key_file_in);

} else {

std::ifstream key_file_in(get_internal_key_path(key_name).c_str(), std::fstream::binary);

if (!key_file_in) {

// TODO: include key name in error message

throw Error("Unable to open key file - have you unlocked/initialized this repository yet?");

}

key_file.load(key_file_in);

}

static bool decrypt_repo_key (Key_file& key_file, const char* key_name, uint32_t key_version, const std::vector<std::string>& secret_keys, const std::string& keys_path)

{

std::exception_ptr gpg_error;

for (std::vector<std::string>::const_iterator seckey(secret_keys.begin()); seckey != secret_keys.end(); ++seckey) {

std::ostringstream path_builder;

path_builder << keys_path << '/' << (key_name ? key_name : "default") << '/' << key_version << '/' << *seckey << ".gpg";

std::string path(path_builder.str());

if (access(path.c_str(), F_OK) == 0) {

std::stringstream decrypted_contents;

try {

gpg_decrypt_from_file(path, decrypted_contents);

} catch (const Gpg_error&) {

gpg_error = std::current_exception();

continue;

}

Key_file this_version_key_file;

this_version_key_file.load(decrypted_contents);

const Key_file::Entry* this_version_entry = this_version_key_file.get(key_version);

if (!this_version_entry) {

throw Error("GPG-encrypted keyfile is malformed because it does not contain expected key version");

}

if (!same_key_name(key_name, this_version_key_file.get_key_name())) {

throw Error("GPG-encrypted keyfile is malformed because it does not contain expected key name");

}

key_file.set_key_name(key_name);

key_file.add(*this_version_entry);

return true;

}

if (gpg_error) {

std::rethrow_exception(gpg_error);

}

return false;

}

static bool decrypt_repo_keys (std::vector<Key_file>& key_files, uint32_t key_version, const std::vector<std::string>& secret_keys, const std::string& keys_path)

{

bool successful = false;

std::vector<std::string> dirents;

if (access(keys_path.c_str(), F_OK) == 0) {

dirents = get_directory_contents(keys_path.c_str());

}

for (std::vector<std::string>::const_iterator dirent(dirents.begin()); dirent != dirents.end(); ++dirent) {

const char* key_name = 0;

if (*dirent != "default") {

if (!validate_key_name(dirent->c_str())) {

continue;

}

key_name = dirent->c_str();

}

Key_file key_file;

if (decrypt_repo_key(key_file, key_name, key_version, secret_keys, keys_path)) {

key_files.push_back(key_file);

successful = true;

}

return successful;

}

static void encrypt_repo_key (const char* key_name, const Key_file::Entry& key, const std::vector<std::pair<std::string, bool> >& collab_keys, const std::string& keys_path, std::vector<std::string>* new_files)

{

std::string key_file_data;

{

Key_file this_version_key_file;

this_version_key_file.set_key_name(key_name);

this_version_key_file.add(key);

key_file_data = this_version_key_file.store_to_string();

}

for (std::vector<std::pair<std::string, bool> >::const_iterator collab(collab_keys.begin()); collab != collab_keys.end(); ++collab) {

const std::string& fingerprint(collab->first);

const bool key_is_trusted(collab->second);

std::ostringstream path_builder;

path_builder << keys_path << '/' << (key_name ? key_name : "default") << '/' << key.version << '/' << fingerprint << ".gpg";

std::string path(path_builder.str());

if (access(path.c_str(), F_OK) == 0) {

continue;

}

mkdir_parent(path);

gpg_encrypt_to_file(path, fingerprint, key_is_trusted, key_file_data.data(), key_file_data.size());

new_files->push_back(path);

}

static int parse_plumbing_options (const char** key_name, const char** key_file, int argc, const char** argv)

{

Options_list options;

options.push_back(Option_def("-k", key_name));

options.push_back(Option_def("--key-name", key_name));

options.push_back(Option_def("--key-file", key_file));

return parse_options(options, argc, argv);

}

// Encrypt contents of stdin and write to stdout

int clean (int argc, const char** argv)

{

const char* key_name = 0;

const char* key_path = 0;

const char* legacy_key_path = 0;

int argi = parse_plumbing_options(&key_name, &key_path, argc, argv);

if (argc - argi == 0) {

} else if (!key_name && !key_path && argc - argi == 1) { // Deprecated - for compatibility with pre-0.4

legacy_key_path = argv[argi];

} else {

std::clog << "Usage: git-crypt clean [--key-name=NAME] [--key-file=PATH]" << std::endl;

return 2;

}

Key_file key_file;

load_key(key_file, key_name, key_path, legacy_key_path);

const Key_file::Entry* key = key_file.get_latest();

if (!key) {

std::clog << "git-crypt: error: key file is empty" << std::endl;

return 1;

}

// Read the entire file

Hmac_sha1_state hmac(key->hmac_key, HMAC_KEY_LEN); // Calculate the file's SHA1 HMAC as we go

uint64_t file_size = 0; // Keep track of the length, make sure it doesn't get too big

std::string file_contents; // First 8MB or so of the file go here

temp_fstream temp_file; // The rest of the file spills into a temporary file on disk

temp_file.exceptions(std::fstream::badbit);

char buffer[1024];

while (std::cin && file_size < Aes_ctr_encryptor::MAX_CRYPT_BYTES) {

std::cin.read(buffer, sizeof(buffer));

const size_t bytes_read = std::cin.gcount();

hmac.add(reinterpret_cast<unsigned char*>(buffer), bytes_read);

file_size += bytes_read;

if (file_size <= 8388608) {

file_contents.append(buffer, bytes_read);

} else {

if (!temp_file.is_open()) {

temp_file.open(std::fstream::in | std::fstream::out | std::fstream::binary | std::fstream::app);

}

temp_file.write(buffer, bytes_read);

}

// Make sure the file isn't so large we'll overflow the counter value (which would doom security)

if (file_size >= Aes_ctr_encryptor::MAX_CRYPT_BYTES) {

std::clog << "git-crypt: error: file too long to encrypt securely" << std::endl;

return 1;

}

// We use an HMAC of the file as the encryption nonce (IV) for CTR mode.

// By using a hash of the file we ensure that the encryption is

// deterministic so git doesn't think the file has changed when it really

// hasn't. CTR mode with a synthetic IV is provably semantically secure

// under deterministic CPA as long as the synthetic IV is derived from a

// secure PRF applied to the message. Since HMAC-SHA1 is a secure PRF, this

// encryption scheme is semantically secure under deterministic CPA.

// Informally, consider that if a file changes just a tiny bit, the IV will

// be completely different, resulting in a completely different ciphertext

// that leaks no information about the similarities of the plaintexts. Also,

// since we're using the output from a secure hash function plus a counter

// as the input to our block cipher, we should never have a situation where

// two different plaintext blocks get encrypted with the same CTR value. A

// nonce will be reused only if the entire file is the same, which leaks no

// information except that the files are the same.

// To prevent an attacker from building a dictionary of hash values and then

// looking up the nonce (which must be stored in the clear to allow for

// decryption), we use an HMAC as opposed to a straight hash.

// Note: Hmac_sha1_state::LEN >= Aes_ctr_encryptor::NONCE_LEN

unsigned char digest[Hmac_sha1_state::LEN];

hmac.get(digest);

// Write a header that...

std::cout.write("\0GITCRYPT\0", 10); // ...identifies this as an encrypted file

std::cout.write(reinterpret_cast<char*>(digest), Aes_ctr_encryptor::NONCE_LEN); // ...includes the nonce

// Now encrypt the file and write to stdout

Aes_ctr_encryptor aes(key->aes_key, digest);

// First read from the in-memory copy

const unsigned char* file_data = reinterpret_cast<const unsigned char*>(file_contents.data());

size_t file_data_len = file_contents.size();

while (file_data_len > 0) {

const size_t buffer_len = std::min(sizeof(buffer), file_data_len);

aes.process(file_data, reinterpret_cast<unsigned char*>(buffer), buffer_len);

std::cout.write(buffer, buffer_len);

file_data += buffer_len;

file_data_len -= buffer_len;

}

// Then read from the temporary file if applicable

if (temp_file.is_open()) {

temp_file.seekg(0);

while (temp_file.peek() != -1) {

temp_file.read(buffer, sizeof(buffer));

const size_t buffer_len = temp_file.gcount();

aes.process(reinterpret_cast<unsigned char*>(buffer),

reinterpret_cast<unsigned char*>(buffer),

buffer_len);

std::cout.write(buffer, buffer_len);

}

return 0;

}

static int decrypt_file_to_stdout (const Key_file& key_file, const unsigned char* header, std::istream& in)

{

const unsigned char* nonce = header + 10;

uint32_t key_version = 0; // TODO: get the version from the file header

const Key_file::Entry* key = key_file.get(key_version);

if (!key) {

std::clog << "git-crypt: error: key version " << key_version << " not available - please unlock with the latest version of the key." << std::endl;

return 1;

}

Aes_ctr_decryptor aes(key->aes_key, nonce);

Hmac_sha1_state hmac(key->hmac_key, HMAC_KEY_LEN);

while (in) {

unsigned char buffer[1024];

in.read(reinterpret_cast<char*>(buffer), sizeof(buffer));

aes.process(buffer, buffer, in.gcount());

hmac.add(buffer, in.gcount());

std::cout.write(reinterpret_cast<char*>(buffer), in.gcount());

}

unsigned char digest[Hmac_sha1_state::LEN];

hmac.get(digest);

if (!leakless_equals(digest, nonce, Aes_ctr_decryptor::NONCE_LEN)) {

std::clog << "git-crypt: error: encrypted file has been tampered with!" << std::endl;

// Although we've already written the tampered file to stdout, exiting

// with a non-zero status will tell git the file has not been filtered,

// so git will not replace it.

return 1;

}

return 0;

}

// Decrypt contents of stdin and write to stdout

int smudge (int argc, const char** argv)

{

const char* key_name = 0;

const char* key_path = 0;

const char* legacy_key_path = 0;

int argi = parse_plumbing_options(&key_name, &key_path, argc, argv);

if (argc - argi == 0) {

} else if (!key_name && !key_path && argc - argi == 1) { // Deprecated - for compatibility with pre-0.4

legacy_key_path = argv[argi];

} else {

std::clog << "Usage: git-crypt smudge [--key-name=NAME] [--key-file=PATH]" << std::endl;

return 2;

}

Key_file key_file;

load_key(key_file, key_name, key_path, legacy_key_path);

// Read the header to get the nonce and make sure it's actually encrypted

unsigned char header[10 + Aes_ctr_decryptor::NONCE_LEN];

std::cin.read(reinterpret_cast<char*>(header), sizeof(header));

if (std::cin.gcount() != sizeof(header) || std::memcmp(header, "\0GITCRYPT\0", 10) != 0) {

// File not encrypted - just copy it out to stdout

std::clog << "git-crypt: Warning: file not encrypted" << std::endl;

std::clog << "git-crypt: Run 'git-crypt status' to make sure all files are properly encrypted." << std::endl;

std::clog << "git-crypt: If 'git-crypt status' reports no problems, then an older version of" << std::endl;

std::clog << "git-crypt: this file may be unencrypted in the repository's history. If this" << std::endl;

std::clog << "git-crypt: file contains sensitive information, you can use 'git filter-branch'" << std::endl;

std::clog << "git-crypt: to remove its old versions from the history." << std::endl;

std::cout.write(reinterpret_cast<char*>(header), std::cin.gcount()); // include the bytes which we already read

std::cout << std::cin.rdbuf();

return 0;

}

return decrypt_file_to_stdout(key_file, header, std::cin);

}

int diff (int argc, const char** argv)

{

const char* key_name = 0;

const char* key_path = 0;

const char* filename = 0;

const char* legacy_key_path = 0;

int argi = parse_plumbing_options(&key_name, &key_path, argc, argv);

if (argc - argi == 1) {

filename = argv[argi];

} else if (!key_name && !key_path && argc - argi == 2) { // Deprecated - for compatibility with pre-0.4

legacy_key_path = argv[argi];

filename = argv[argi + 1];

} else {

std::clog << "Usage: git-crypt diff [--key-name=NAME] [--key-file=PATH] FILENAME" << std::endl;

return 2;

}

Key_file key_file;

load_key(key_file, key_name, key_path, legacy_key_path);

// Open the file

std::ifstream in(filename, std::fstream::binary);

if (!in) {

std::clog << "git-crypt: " << filename << ": unable to open for reading" << std::endl;

return 1;

}

in.exceptions(std::fstream::badbit);

// Read the header to get the nonce and determine if it's actually encrypted

unsigned char header[10 + Aes_ctr_decryptor::NONCE_LEN];

in.read(reinterpret_cast<char*>(header), sizeof(header));

if (in.gcount() != sizeof(header) || std::memcmp(header, "\0GITCRYPT\0", 10) != 0) {

// File not encrypted - just copy it out to stdout

std::cout.write(reinterpret_cast<char*>(header), in.gcount()); // include the bytes which we already read

std::cout << in.rdbuf();

return 0;

}

// Go ahead and decrypt it

return decrypt_file_to_stdout(key_file, header, in);

}

void help_init (std::ostream& out)

{

// |--------------------------------------------------------------------------------| 80 chars

out << "Usage: git-crypt init [OPTIONS]" << std::endl;

out << std::endl;

out << " -k, --key-name KEYNAME Initialize the given key, instead of the default" << std::endl;

out << std::endl;

}

int init (int argc, const char** argv)

{

const char* key_name = 0;

Options_list options;

options.push_back(Option_def("-k", &key_name));

options.push_back(Option_def("--key-name", &key_name));

int argi = parse_options(options, argc, argv);

if (!key_name && argc - argi == 1) {

std::clog << "Warning: 'git-crypt init' with a key file is deprecated as of git-crypt 0.4" << std::endl;

std::clog << "and will be removed in a future release. Please get in the habit of using" << std::endl;

std::clog << "'git-crypt unlock KEYFILE' instead." << std::endl;

return unlock(argc, argv);

}

if (argc - argi != 0) {

std::clog << "Error: git-crypt init takes no arguments" << std::endl;

help_init(std::clog);

return 2;

}

if (key_name) {

validate_key_name_or_throw(key_name);

}

std::string internal_key_path(get_internal_key_path(key_name));

if (access(internal_key_path.c_str(), F_OK) == 0) {

// TODO: add a -f option to reinitialize the repo anyways (this should probably imply a refresh)

// TODO: include key_name in error message

std::clog << "Error: this repository has already been initialized with git-crypt." << std::endl;

return 1;

}

// 1. Generate a key and install it

std::clog << "Generating key..." << std::endl;

Key_file key_file;

key_file.set_key_name(key_name);

key_file.generate();

mkdir_parent(internal_key_path);

if (!key_file.store_to_file(internal_key_path.c_str())) {

std::clog << "Error: " << internal_key_path << ": unable to write key file" << std::endl;

return 1;

}

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git-crypt/commands.cpp at master · adamluzsi-backup/git-crypt · GitHub

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