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PAM: support the authentication facility

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Implement the pam_sm_authenticate method, using the noop argument of
lzc_load_key to do a passphrase check without actually loading the key.

This allows using ZFS as the source of truth for user passwords,
without storing any password hashes in /etc or using other PAM modules.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Felix Dörre <felix@dogcraft.de>
Signed-off-by: Val Packett <val@packett.cool>
Closes #14789
This commit is contained in:
Val Packett 2023-04-27 13:49:03 -03:00 committed by GitHub
parent ee728008a4
commit ae0d0f0e04
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 49 additions and 14 deletions
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63
contrib/pam_zfs_key/pam_zfs_key.c
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@ -371,7 +371,7 @@ change_key(pam_handle_t *pamh, const char *ds_name,
static int
decrypt_mount(pam_handle_t *pamh, const char *ds_name,
const char *passphrase)
const char *passphrase, boolean_t noop)
{
zfs_handle_t *ds = zfs_open(g_zfs, ds_name, ZFS_TYPE_FILESYSTEM);
if (ds == NULL) {
@ -383,7 +383,7 @@ decrypt_mount(pam_handle_t *pamh, const char *ds_name,
zfs_close(ds);
return (-1);
}
int ret = lzc_load_key(ds_name, B_FALSE, (uint8_t *)key->value,
int ret = lzc_load_key(ds_name, noop, (uint8_t *)key->value,
WRAPPING_KEY_LEN);
pw_free(key);
if (ret) {
@ -391,12 +391,16 @@ decrypt_mount(pam_handle_t *pamh, const char *ds_name,
zfs_close(ds);
return (-1);
}
if (noop) {
goto out;
}
ret = zfs_mount(ds, NULL, 0);
if (ret) {
pam_syslog(pamh, LOG_ERR, "mount failed: %d", ret);
zfs_close(ds);
return (-1);
}
out:
zfs_close(ds);
return (0);
}
@ -443,13 +447,13 @@ zfs_key_config_load(pam_handle_t *pamh, zfs_key_config_t *config,
config->homes_prefix = strdup("rpool/home");
if (config->homes_prefix == NULL) {
pam_syslog(pamh, LOG_ERR, "strdup failure");
return (-1);
return (PAM_SERVICE_ERR);
}
config->runstatedir = strdup(RUNSTATEDIR "/pam_zfs_key");
if (config->runstatedir == NULL) {
pam_syslog(pamh, LOG_ERR, "strdup failure");
free(config->homes_prefix);
return (-1);
return (PAM_SERVICE_ERR);
}
const char *name;
if (pam_get_user(pamh, &name, NULL) != PAM_SUCCESS) {
@ -457,13 +461,13 @@ zfs_key_config_load(pam_handle_t *pamh, zfs_key_config_t *config,
"couldn't get username from PAM stack");
free(config->runstatedir);
free(config->homes_prefix);
return (-1);
return (PAM_SERVICE_ERR);
}
struct passwd *entry = getpwnam(name);
if (!entry) {
free(config->runstatedir);
free(config->homes_prefix);
return (-1);
return (PAM_USER_UNKNOWN);
}
config->uid = entry->pw_uid;
config->username = name;
@ -484,7 +488,7 @@ zfs_key_config_load(pam_handle_t *pamh, zfs_key_config_t *config,
config->homedir = strdup(entry->pw_dir);
}
}
return (0);
return (PAM_SUCCESS);
}
static void
@ -644,12 +648,43 @@ PAM_EXTERN int
pam_sm_authenticate(pam_handle_t *pamh, int flags,
int argc, const char **argv)
{
(void) flags, (void) argc, (void) argv;
(void) flags;
if (pw_fetch_lazy(pamh) == NULL) {
return (PAM_AUTH_ERR);
if (geteuid() != 0) {
pam_syslog(pamh, LOG_ERR,
"Cannot zfs_mount when not being root.");
return (PAM_SERVICE_ERR);
}
zfs_key_config_t config;
int config_err = zfs_key_config_load(pamh, &config, argc, argv);
if (config_err != PAM_SUCCESS) {
return (config_err);
}
const pw_password_t *token = pw_fetch_lazy(pamh);
if (token == NULL) {
zfs_key_config_free(&config);
return (PAM_AUTH_ERR);
}
if (pam_zfs_init(pamh) != 0) {
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
char *dataset = zfs_key_config_get_dataset(&config);
if (!dataset) {
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
if (decrypt_mount(pamh, dataset, token->value, B_TRUE) == -1) {
free(dataset);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_AUTH_ERR);
}
free(dataset);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SUCCESS);
}
@ -673,7 +708,7 @@ pam_sm_chauthtok(pam_handle_t *pamh, int flags,
return (PAM_PERM_DENIED);
}
zfs_key_config_t config;
if (zfs_key_config_load(pamh, &config, argc, argv) == -1) {
if (zfs_key_config_load(pamh, &config, argc, argv) != PAM_SUCCESS) {
return (PAM_SERVICE_ERR);
}
if (config.uid < 1000) {
@ -754,7 +789,7 @@ pam_sm_open_session(pam_handle_t *pamh, int flags,
return (PAM_SUCCESS);
}
zfs_key_config_t config;
if (zfs_key_config_load(pamh, &config, argc, argv) != 0) {
if (zfs_key_config_load(pamh, &config, argc, argv) != PAM_SUCCESS) {
return (PAM_SESSION_ERR);
}
@ -784,7 +819,7 @@ pam_sm_open_session(pam_handle_t *pamh, int flags,
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
if (decrypt_mount(pamh, dataset, token->value) == -1) {
if (decrypt_mount(pamh, dataset, token->value, B_FALSE) == -1) {
free(dataset);
pam_zfs_free();
zfs_key_config_free(&config);
@ -813,7 +848,7 @@ pam_sm_close_session(pam_handle_t *pamh, int flags,
return (PAM_SUCCESS);
}
zfs_key_config_t config;
if (zfs_key_config_load(pamh, &config, argc, argv) != 0) {
if (zfs_key_config_load(pamh, &config, argc, argv) != PAM_SUCCESS) {
return (PAM_SESSION_ERR);
}
if (config.uid < 1000) {