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#include <cerrno>
#include <cstring>
#include <filesystem>
#include <print>
#include <stdexcept>
#include <string>
#include <string_view>
#include <fcntl.h>
#include <pwd.h>
#include <sys/stat.h>
#include <unistd.h>
#include <security/pam_modules.h>
#include <sqlite3.h>
namespace pam_xdg {
constexpr const std::string_view USER_DIRECTORY = "/run/user";
constexpr const std::string_view DB_PATH = "/run/pam_xdg.db";
void open_db(sqlite3 **db, const std::filesystem::path &path, int flags) {
auto rc = sqlite3_open_v2(path.c_str(), db, flags, nullptr);
if (rc != SQLITE_OK) {
throw std::runtime_error(std::string("failed to open database"));
}
}
void init_db(sqlite3 *db) {
auto rc = sqlite3_exec(
db, "CREATE TABLE IF NOT EXISTS SESSIONS(USERNAME TEXT, LOGINS INT)",
nullptr, nullptr, nullptr);
if (rc != SQLITE_OK) {
throw std::runtime_error(
std::string("failed to init database: {}", sqlite3_errmsg(db)));
}
}
void init_session(sqlite3 *db, std::string_view username) {
const auto *query =
"INSERT OR IGNORE INTO SESSIONS(USERNAME, LOGINS) VALUES(?, 0)";
sqlite3_stmt *stmt;
int rc;
rc = sqlite3_prepare_v2(db, query, -1, &stmt, NULL);
if (rc != SQLITE_OK) {
throw std::runtime_error(
std::format("failed to prepare stmt: {}", sqlite3_errmsg(db)));
}
rc = sqlite3_bind_text(stmt, 1, username.data(), username.length(), nullptr);
if (rc != SQLITE_OK) {
sqlite3_finalize(stmt);
throw std::runtime_error(std::string("failed to bind text to stmt"));
}
rc = sqlite3_step(stmt);
if (rc != SQLITE_DONE) {
sqlite3_finalize(stmt);
throw std::runtime_error(std::string("failed to step stmt"));
}
sqlite3_finalize(stmt);
}
void record_login(sqlite3 *db, std::string_view username) {
const auto *query = "UPDATE SESSIONS SET LOGINS=LOGINS+1 WHERE USERNAME=?";
sqlite3_stmt *stmt;
int rc;
rc = sqlite3_prepare_v2(db, query, -1, &stmt, nullptr);
if (rc != SQLITE_OK) {
throw std::runtime_error(
std::string("failed to prepare stmt: {}", sqlite3_errmsg(db)));
}
rc = sqlite3_bind_text(stmt, 1, username.data(), username.length(), nullptr);
if (rc != SQLITE_OK) {
sqlite3_finalize(stmt);
throw std::runtime_error(std::string("failed to bind text"));
}
rc = sqlite3_step(stmt);
if (rc != SQLITE_DONE) {
sqlite3_finalize(stmt);
throw std::runtime_error(std::string("failed to step stmt"));
}
sqlite3_finalize(stmt);
}
void record_logout(sqlite3 *db, std::string_view username) {
const auto *query = "UPDATE SESSIONS SET LOGINS=LOGINS-1 WHERE USERNAME=?";
sqlite3_stmt *stmt;
int rc;
rc = sqlite3_prepare_v2(db, query, -1, &stmt, nullptr);
if (rc != SQLITE_OK) {
throw std::runtime_error(
std::string("failed to prepare stmt: {}", sqlite3_errmsg(db)));
}
rc = sqlite3_bind_text(stmt, 1, username.data(), username.length(), nullptr);
if (rc != SQLITE_OK) {
sqlite3_finalize(stmt);
throw std::runtime_error(std::string("failed to bind text"));
}
rc = sqlite3_step(stmt);
if (rc != SQLITE_DONE) {
sqlite3_finalize(stmt);
throw std::runtime_error(std::string("failed to step stmt"));
}
sqlite3_finalize(stmt);
}
bool is_logged_in(sqlite3 *db, std::string_view username) {
const auto *query = "SELECT LOGINS FROM SESSIONS WHERE USERNAME=?";
sqlite3_stmt *stmt;
int rc;
rc = sqlite3_prepare_v2(db, query, -1, &stmt, nullptr);
if (rc != SQLITE_OK) {
throw std::runtime_error(
std::format("failed to prepare stmt: {}", sqlite3_errmsg(db)));
}
rc = sqlite3_bind_text(stmt, 1, username.data(), username.length(), nullptr);
if (rc != SQLITE_OK) {
sqlite3_finalize(stmt);
throw std::runtime_error(std::string("failed to bind text"));
}
rc = sqlite3_step(stmt);
if (rc != SQLITE_ROW) {
sqlite3_finalize(stmt);
throw std::runtime_error(std::string("failed to step stmt"));
}
int logins = sqlite3_column_int(stmt, 0);
sqlite3_finalize(stmt);
return (logins > 0);
}
void touch(const std::filesystem::path &path, int mode) {
auto fd = creat(path.c_str(), mode);
if (fd == -1) {
throw std::runtime_error(std::format("failed to touch file: {} {}",
path.c_str(), std::strerror(errno)));
}
close(fd);
}
void create_directory(const std::filesystem::path &path, std::uint16_t owner,
int mode) {
int rc;
rc = mkdir(path.c_str(), mode);
if (rc == -1) {
throw std::runtime_error(std::format("failed to mkdir: {} {}", path.c_str(),
std::strerror(errno)));
}
rc = chown(path.c_str(), owner, owner);
if (rc == -1) {
throw std::runtime_error(std::format("failed to chown: {} {}", path.c_str(),
std::strerror(errno)));
}
}
} // namespace pam_xdg
extern "C" int pam_sm_open_session(pam_handle_t *pamh,
[[gnu::unused]] int flags,
[[gnu::unused]] int argc,
[[gnu::unused]] const char **argv) {
const void *data;
if (pam_get_item(pamh, PAM_USER, &data) != PAM_SUCCESS) {
std::println(stderr, "failed to get pam item PAM_USER");
return PAM_SESSION_ERR;
}
auto *username = static_cast<const char *>(data);
if (std::string_view(username) == "root") {
return 0;
}
auto passwd = getpwnam(username);
auto uid = passwd->pw_uid;
auto xdg_runtime_dir =
std::filesystem::path(pam_xdg::USER_DIRECTORY) / std::format("{}", uid);
sqlite3 *db;
try {
if (!std::filesystem::exists(pam_xdg::DB_PATH)) {
pam_xdg::touch(pam_xdg::DB_PATH, 0600);
pam_xdg::open_db(&db, pam_xdg::DB_PATH,
SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE);
pam_xdg::init_db(db);
} else {
pam_xdg::open_db(&db, pam_xdg::DB_PATH, SQLITE_OPEN_READWRITE);
}
pam_xdg::init_session(db, username);
if (!pam_xdg::is_logged_in(db, username)) {
if (!std::filesystem::exists(pam_xdg::USER_DIRECTORY)) {
pam_xdg::create_directory(pam_xdg::USER_DIRECTORY, 0, 0755);
}
if (!std::filesystem::is_directory(pam_xdg::USER_DIRECTORY)) {
throw std::runtime_error(
std::format("{} is not a directory", pam_xdg::USER_DIRECTORY));
}
pam_xdg::create_directory(std::filesystem::path(pam_xdg::USER_DIRECTORY) /
std::format("{}", uid),
uid, 0700);
}
pam_xdg::record_login(db, username);
auto envvar = std::format("XDG_RUNTIME_DIR={}", xdg_runtime_dir.c_str());
if (pam_putenv(pamh, envvar.c_str()) != PAM_SUCCESS) {
throw std::runtime_error(std::format("failed to putenv: {}", envvar));
}
} catch (const std::exception &e) {
std::println(stderr, "{}", e.what());
return PAM_SESSION_ERR;
}
return PAM_SUCCESS;
}
extern "C" int pam_sm_close_session(pam_handle_t *pam,
[[gnu::unused]] int flags,
[[gnu::unused]] int argc,
[[gnu::unused]] const char **argv) {
const void *data;
if (pam_get_item(pam, PAM_USER, &data) != PAM_SUCCESS) {
std::println(stderr, "failed to get pam item PAM_USER");
return PAM_SESSION_ERR;
}
auto *username = static_cast<const char *>(data);
if (std::string_view(username) == "root") {
return 0;
}
auto passwd = getpwnam(username);
auto uid = passwd->pw_uid;
auto xdg_runtime_dir =
std::filesystem::path(pam_xdg::USER_DIRECTORY) / std::format("{}", uid);
sqlite3 *db;
try {
pam_xdg::open_db(&db, pam_xdg::DB_PATH, SQLITE_OPEN_READWRITE);
pam_xdg::record_logout(db, username);
if (!pam_xdg::is_logged_in(db, username)) {
std::filesystem::remove_all(xdg_runtime_dir);
}
} catch (const std::exception &e) {
std::println(stderr, "{}", e.what());
return PAM_SESSION_ERR;
}
return PAM_SUCCESS;
}
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