Serge E. Hallyn wrote:
> Quoting Oren Laadan (orenl@xxxxxxxxxxxxxxx):
>> -int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
>> +int
>> +ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size, int req_id)
>> {
>> uid_t euid;
>> gid_t egid;
>> + int lid = 0;
>> int id, err;
>>
>> if (size > IPCMNI)
>> @@ -268,28 +270,41 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
>> if (ids->in_use >= size)
>> return -ENOSPC;
>>
>> + if (req_id >= 0)
>> + lid = ipcid_to_idx(req_id);
>> +
>> spin_lock_init(&new->lock);
>> new->deleted = 0;
>> rcu_read_lock();
>> spin_lock(&new->lock);
>>
>> - err = idr_get_new(&ids->ipcs_idr, new, &id);
>> + err = idr_get_new_above(&ids->ipcs_idr, new, lid, &id);
>> if (err) {
>> spin_unlock(&new->lock);
>> rcu_read_unlock();
>> return err;
>> }
>>
>> + if (req_id >= 0) {
>> + if (id != lid) {
>> + idr_remove(&ids->ipcs_idr, id);
>> + spin_unlock(&new->lock);
>> + rcu_read_unlock();
>> + return -EBUSY;
>> + }
>> + new->seq = req_id / SEQ_MULTIPLIER;
>
> Should this be
>
> new->seq = req_id % ids->seq_max;
>
> ?
This is how the user-visible IPC id is constructed:
static inline int ipc_buildid(int id, int seq)
{
return SEQ_MULTIPLIER * seq + id;
}
and I want to get the original 'seq' .... (the 'id' in this function is
an in-kernel identifier)
>
>> + } else {
>> + new->seq = ids->seq++;
>> + if (ids->seq > ids->seq_max)
>> + ids->seq = 0;
>> + }
>> +
>> ids->in_use++;
>>
>> current_euid_egid(&euid, &egid);
>> new->cuid = new->uid = euid;
>> new->gid = new->cgid = egid;
>>
>> - new->seq = ids->seq++;
>> - if(ids->seq > ids->seq_max)
>> - ids->seq = 0;
>> -
>
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