static bool sss_mc_is_valid_rec(struct sss_mc_ctx *mcc, struct sss_mc_rec *rec)
{
struct sss_mc_rec *self;
uint32_t slot;
if (((uint8_t *)rec < mcc->data_table) ||
((uint8_t *)rec > (mcc->data_table + mcc->dt_size - MC_SLOT_SIZE))) {
return false;
}
if ((rec->b1 == MC_INVALID_VAL) ||
(rec->b1 != rec->b2)) {
return false;
}
if (!MC_CHECK_RECORD_LENGTH(mcc, rec)) {
return false;
}
if (rec->expire == MC_INVALID_VAL64) {
return false;
}
/* rec->next can be invalid if there are no next records */
if (rec->hash1 == MC_INVALID_VAL32) {
return false;
} else {
self = NULL;
slot = mcc->hash_table[rec->hash1];
while (slot != MC_INVALID_VAL32 && self != rec) {
self = MC_SLOT_TO_PTR(mcc->data_table, slot, struct sss_mc_rec);
slot = self->next;
}
if (self != rec) {
return false;
}
}
if (rec->hash2 != MC_INVALID_VAL32) {
self = NULL;
slot = mcc->hash_table[rec->hash2];
while (slot != MC_INVALID_VAL32 && self != rec) {
self = MC_SLOT_TO_PTR(mcc->data_table, slot, struct sss_mc_rec);
slot = self->next;
}
if (self != rec) {
return false;
}
}
errno_t sss_nss_mc_get_record(struct sss_cli_mc_ctx *ctx,
uint32_t slot, struct sss_mc_rec **_rec)
{
struct sss_mc_rec *rec;
struct sss_mc_rec *copy_rec = NULL;
size_t buf_size = 0;
size_t rec_len;
uint32_t b1;
uint32_t b2;
bool copy_ok;
int count;
int ret;
/* try max 5 times */
for (count = 5; count > 0; count--) {
rec = MC_SLOT_TO_PTR(ctx->data_table, slot, struct sss_mc_rec);
/* fetch record length */
b1 = rec->b1;
__sync_synchronize();
rec_len = rec->len;
__sync_synchronize();
b2 = rec->b2;
if (!MC_VALID_BARRIER(b1) || b1 != b2) {
/* record is inconsistent, retry */
continue;
}
if (!MC_CHECK_RECORD_LENGTH(ctx, rec)) {
/* record has invalid length */
free(copy_rec);
return EINVAL;
}
if (rec_len > buf_size) {
free(copy_rec);
copy_rec = malloc(rec_len);
if (!copy_rec) {
ret = ENOMEM;
goto done;
}
buf_size = rec_len;
}
/* we cannot access data directly, we must copy data and then
* access the copy */
MEMCPY_WITH_BARRIERS(copy_ok, copy_rec, rec, rec_len);
/* we must check data is consistent again after the copy */
if (copy_ok && b1 == copy_rec->b2) {
/* record is consistent, use it */
break;
}
}
if (count == 0) {
/* couldn't successfully read header we have to give up */
ret = EIO;
goto done;
}
*_rec = copy_rec;
ret = 0;
done:
if (ret) {
free(copy_rec);
*_rec = NULL;
}
return ret;
}
