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auth/pam: auto-retry once on PAM_SYSTEM_ERR with configurable delay #1079

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auth/pam: auto-retry once on PAM_SYSTEM_ERR with configurable delay #1079

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15 changes: 15 additions & 0 deletions assets/example.conf
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,21 @@ general {
hide_cursor = false
}

# auth:pam:retry_on_error — when PAM returns a transient system error (e.g.
# SSSD's krb5_child process was killed by its hardcoded 300-second keep-alive
# timer before the user submitted their password), hyprlock will automatically
# retry authentication once after retry_delay milliseconds using the same
# credentials. This avoids having to enter the password twice after long idle
# periods on systems using Kerberos/SSSD authentication.
# Note: only PAM_SYSTEM_ERR triggers a retry; PAM_AUTH_ERR (wrong password)
# is never retried.
# auth {
# pam {
# retry_on_error = true
# retry_delay = 3000 # in milliseconds
# }
# }

# uncomment to enable fingerprint authentication
# auth {
# fingerprint {
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39 changes: 36 additions & 3 deletions src/auth/Pam.cpp
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Expand Up @@ -46,7 +46,10 @@ int conv(int num_msg, const struct pam_message** msg, struct pam_response** resp
CONVERSATIONSTATE->prompt = PROMPT;
g_pHyprlock->enqueueForceUpdateTimers();

CONVERSATIONSTATE->waitForInput();
// On auto-retry after a transient system error, the password is
// already set — skip blocking and reuse it directly.
if (!CONVERSATIONSTATE->autoRetry)
CONVERSATIONSTATE->waitForInput();
}

// Needed for unlocks via SIGUSR1
Expand Down Expand Up @@ -77,8 +80,12 @@ int conv(int num_msg, const struct pam_message** msg, struct pam_response** resp
}

CPam::CPam() {
static const auto PAMMODULE = g_pConfigManager->getValue<Hyprlang::STRING>("auth:pam:module");
m_sPamModule = *PAMMODULE;
static const auto PAMMODULE = g_pConfigManager->getValue<Hyprlang::STRING>("auth:pam:module");
static const auto RETRYONERROR = g_pConfigManager->getValue<Hyprlang::INT>("auth:pam:retry_on_error");
static const auto RETRYDELAY = g_pConfigManager->getValue<Hyprlang::INT>("auth:pam:retry_delay");
m_sPamModule = *PAMMODULE;
m_bRetryOnError = *RETRYONERROR;
m_iRetryDelayMs = *RETRYDELAY;

if (!std::filesystem::exists(std::filesystem::path("/etc/pam.d/") / m_sPamModule)) {
Log::logger->log(Log::ERR, R"(Pam module "/etc/pam.d/{}" does not exist! Falling back to "/etc/pam.d/su")", m_sPamModule);
Expand Down Expand Up @@ -142,6 +149,31 @@ bool CPam::auth() {

m_sConversationState.waitingForPamAuth = false;

// PAM_SYSTEM_ERR (4) means an SSSD/PAM infrastructure transient failure,
// not a wrong password. Retry once after a short delay so that the user
// never has to type their password twice due to e.g. a dead krb5_child.
if (m_bRetryOnError && ret == PAM_SYSTEM_ERR && !m_sConversationState.input.empty() &&
!m_sConversationState.terminateRequested && !g_pHyprlock->isFadingOutOrTerminating()) {
Log::logger->log(Log::INFO, "auth: PAM_SYSTEM_ERR — retrying in {}ms with same credentials", m_iRetryDelayMs);
std::this_thread::sleep_for(std::chrono::milliseconds(m_iRetryDelayMs));

if (!m_sConversationState.terminateRequested && !g_pHyprlock->isFadingOutOrTerminating()) {
m_sConversationState.autoRetry = true;
m_sConversationState.failTextFromPam = false;
m_sConversationState.waitingForPamAuth = true;

pam_handle_t* retryHandle = nullptr;
ret = pam_start(m_sPamModule.c_str(), m_username.c_str(), &localConv, &retryHandle);
if (ret == PAM_SUCCESS)
ret = pam_authenticate(retryHandle, 0);
pam_end(retryHandle, ret);
retryHandle = nullptr;

m_sConversationState.autoRetry = false;
m_sConversationState.waitingForPamAuth = false;
}
}

if (ret != PAM_SUCCESS) {
if (!m_sConversationState.failTextFromPam)
m_sConversationState.failText = ret == PAM_AUTH_ERR ? "Authentication failed" : "pam_authenticate failed";
Expand Down Expand Up @@ -205,5 +237,6 @@ void CPam::resetConversation() {
m_sConversationState.waitingForPamAuth = false;
m_sConversationState.inputRequested = false;
m_sConversationState.failTextFromPam = false;
m_sConversationState.autoRetry = false;
m_bBlockInput = false;
}
5 changes: 4 additions & 1 deletion src/auth/Pam.hpp
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Expand Up @@ -23,6 +23,7 @@ class CPam : public IAuthImplementation {
bool waitingForPamAuth = false;
bool inputRequested = false;
bool failTextFromPam = false;
bool autoRetry = false;
std::atomic_bool terminateRequested = false;
std::function<void()> waitForInput = []() {};
};
Expand All @@ -46,7 +47,9 @@ class CPam : public IAuthImplementation {
std::thread m_thread;
SPamConversationState m_sConversationState;

bool m_bBlockInput = false;
bool m_bBlockInput = false;
bool m_bRetryOnError = true;
int m_iRetryDelayMs = 3000;

std::string m_sPamModule = "";
std::string m_username = "";
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2 changes: 2 additions & 0 deletions src/config/ConfigManager.cpp
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Expand Up @@ -250,6 +250,8 @@ void CConfigManager::init() {

m_config.addConfigValue("auth:pam:enabled", Hyprlang::INT{1});
m_config.addConfigValue("auth:pam:module", Hyprlang::STRING{"hyprlock"});
m_config.addConfigValue("auth:pam:retry_on_error", Hyprlang::INT{1});
m_config.addConfigValue("auth:pam:retry_delay", Hyprlang::INT{3000});
m_config.addConfigValue("auth:fingerprint:enabled", Hyprlang::INT{0});
m_config.addConfigValue("auth:fingerprint:ready_message", Hyprlang::STRING{"(Scan fingerprint to unlock)"});
m_config.addConfigValue("auth:fingerprint:present_message", Hyprlang::STRING{"Scanning fingerprint"});
Expand Down