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pam_zfs_key: support keyfile for filesystem mount in sm_open_session #11247

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pam_zfs_key: support keyfile for filesystem mount in sm_open_session #11247

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174 changes: 127 additions & 47 deletions contrib/pam_zfs_key/pam_zfs_key.c
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Original file line number Diff line number Diff line change
Expand Up @@ -326,38 +326,6 @@ change_key(pam_handle_t *pamh, const char *ds_name,
return (0);
}

static int
decrypt_mount(pam_handle_t *pamh, const char *ds_name,
const char *passphrase)
{
zfs_handle_t *ds = zfs_open(g_zfs, ds_name, ZFS_TYPE_FILESYSTEM);
if (ds == NULL) {
pam_syslog(pamh, LOG_ERR, "dataset %s not found", ds_name);
return (-1);
}
pw_password_t *key = prepare_passphrase(pamh, ds, passphrase, NULL);
if (key == NULL) {
zfs_close(ds);
return (-1);
}
int ret = lzc_load_key(ds_name, B_FALSE, (uint8_t *)key->value,
WRAPPING_KEY_LEN);
pw_free(key);
if (ret) {
pam_syslog(pamh, LOG_ERR, "load_key failed: %d", ret);
zfs_close(ds);
return (-1);
}
ret = zfs_mount(ds, NULL, 0);
if (ret) {
pam_syslog(pamh, LOG_ERR, "mount failed: %d", ret);
zfs_close(ds);
return (-1);
}
zfs_close(ds);
return (0);
}

static int
unmount_unload(pam_handle_t *pamh, const char *ds_name)
{
Expand Down Expand Up @@ -386,6 +354,7 @@ unmount_unload(pam_handle_t *pamh, const char *ds_name)
typedef struct {
char *homes_prefix;
char *runstatedir;
boolean_t convKeyPrompt; /* argv to change prompt forcefully */
char *homedir;
char *dsname;
uid_t uid;
Expand Down Expand Up @@ -425,6 +394,7 @@ zfs_key_config_load(pam_handle_t *pamh, zfs_key_config_t *config,
config->uid = entry->pw_uid;
config->username = name;
config->unmount_and_unload = 1;
config->convKeyPrompt = B_FALSE;
config->dsname = NULL;
config->homedir = NULL;
for (int c = 0; c < argc; c++) {
Expand All @@ -434,6 +404,8 @@ zfs_key_config_load(pam_handle_t *pamh, zfs_key_config_t *config,
} else if (strncmp(argv[c], "runstatedir=", 12) == 0) {
free(config->runstatedir);
config->runstatedir = strdup(argv[c] + 12);
} else if (strcmp(argv[c], "convKeyPrompt") == 0) {
config->convKeyPrompt = B_TRUE;
} else if (strcmp(argv[c], "nounmount") == 0) {
config->unmount_and_unload = 0;
} else if (strcmp(argv[c], "prop_mountpoint") == 0) {
Expand Down Expand Up @@ -593,6 +565,19 @@ zfs_key_config_modify_session_counter(pam_handle_t *pamh,
return (counter_value);
}

static boolean_t
zfs_keylocation_is_prompt(pam_handle_t *pamh, const char *ds_name)
{
zfs_handle_t *ds = zfs_open(g_zfs, ds_name, ZFS_TYPE_FILESYSTEM);
if (ds == NULL) {
pam_syslog(pamh, LOG_ERR, "dataset %s not found", ds_name);
return (B_FALSE);
}
uint64_t keyloc = zfs_prop_get_int(ds, ZFS_PROP_KEYLOCATION);
zfs_close(ds);
return (keyloc == ZFS_KEYLOCATION_PROMPT);
}

__attribute__((visibility("default")))
PAM_EXTERN int
pam_sm_authenticate(pam_handle_t *pamh, int flags,
Expand Down Expand Up @@ -660,11 +645,6 @@ pam_sm_chauthtok(pam_handle_t *pamh, int flags,
}

if ((flags & PAM_UPDATE_AUTHTOK) != 0) {
const pw_password_t *token = pw_get(pamh);
if (token == NULL) {
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
if (pam_zfs_init(pamh) != 0) {
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
Expand All @@ -675,6 +655,18 @@ pam_sm_chauthtok(pam_handle_t *pamh, int flags,
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
/* keyfile won't be overriden unless convKeyPrompt is set */
if (!zfs_keylocation_is_prompt(pamh, dataset) &&
!config.convKeyPrompt) {
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_IGNORE);
}
const pw_password_t *token = pw_get(pamh);
if (token == NULL) {
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
if (change_key(pamh, dataset, token->value) == -1) {
free(dataset);
pam_zfs_free();
Expand Down Expand Up @@ -708,18 +700,11 @@ pam_sm_open_session(pam_handle_t *pamh, int flags,
zfs_key_config_free(&config);
return (PAM_SUCCESS);
}

int counter = zfs_key_config_modify_session_counter(pamh, &config, 1);
if (counter != 1) {
zfs_key_config_free(&config);
return (PAM_SUCCESS);
}

const pw_password_t *token = pw_get(pamh);
if (token == NULL) {
zfs_key_config_free(&config);
return (PAM_SESSION_ERR);
}
if (pam_zfs_init(pamh) != 0) {
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
Expand All @@ -730,20 +715,115 @@ 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) {
free(dataset);
zfs_handle_t *zhp = zfs_open(g_zfs, dataset, ZFS_TYPE_FILESYSTEM);
if (zhp == NULL) {
pam_syslog(pamh, LOG_ERR, "dataset %s not found", dataset);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
/* Fetch the keyformat. Check that the dataset is encrypted. */
uint64_t keyformat = zfs_prop_get_int(zhp, ZFS_PROP_KEYFORMAT);
if (keyformat == ZFS_KEYFORMAT_NONE) {
pam_syslog(pamh, LOG_ERR, "dataset %s not encrypted", dataset);
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SUCCESS);
}
/*
* Check keystatus and load-key if yet
*
* IF keylocation == prompt: load-key use pam's pw token
* IF keylocation == others: load-key use zfs_crypto_load_key()
*/
uint64_t keystatus = zfs_prop_get_int(zhp, ZFS_PROP_KEYSTATUS);
if (keystatus == ZFS_KEYSTATUS_UNAVAILABLE) {
char str_keylocation[MAXNAMELEN];
if (zfs_prop_get(zhp, ZFS_PROP_KEYLOCATION, str_keylocation,
sizeof (str_keylocation), NULL, NULL, 0, B_TRUE) != 0) {
pam_syslog(pamh, LOG_ERR,
"Failed to get keylocation for '%s'", dataset);
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
if (strcmp("prompt", str_keylocation) == 0) {
const pw_password_t *token = pw_get(pamh);
if (token == NULL) {
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SESSION_ERR);
}
pw_password_t *key = prepare_passphrase(pamh, zhp,
token->value, NULL);
if (key == NULL) {
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SESSION_ERR);
}
int ret = lzc_load_key(dataset, B_FALSE,
(uint8_t *)key->value, WRAPPING_KEY_LEN);
pw_free(key);
if (ret) {
pam_syslog(pamh, LOG_ERR,
"pam load_key failed: %d", ret);
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
} else {
int ret = zfs_crypto_load_key(zhp, B_FALSE, NULL);
if (ret) {
pam_syslog(pamh, LOG_ERR,
"zfs load_key failed: %d", ret);
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SERVICE_ERR);
}
}
}
zfs_refresh_properties(zhp);
if (zfs_is_mounted(zhp, NULL)) {
pam_syslog(pamh, LOG_WARNING,
"'%s': filesystem already mounted", dataset);
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SUCCESS);
}
/* assure key is loaded and available */
keystatus = zfs_prop_get_int(zhp, ZFS_PROP_KEYSTATUS);
if (keystatus != ZFS_KEYSTATUS_AVAILABLE) {
pam_syslog(pamh, LOG_ERR, "key not ready: %ld", keystatus);
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SESSION_ERR);
}
/* mount the filesystem */
int ret = zfs_mount(zhp, NULL, 0);
if (ret) {
pam_syslog(pamh, LOG_ERR, "mount failed: %d", ret);
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
return (PAM_SESSION_ERR);
}
/* cleanup */
free(dataset);
zfs_close(zhp);
pam_zfs_free();
zfs_key_config_free(&config);
if (pw_clear(pamh) == -1) {
return (PAM_SERVICE_ERR);
}
return (PAM_SUCCESS);

}

__attribute__((visibility("default")))
Expand Down