Messages in this thread Patch in this message | | | From | Claudio Scordino <> | Subject | Re: [PATCH] getrusage sucks | Date | Fri, 11 Nov 2005 23:38:19 +0100 |
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> > > You need to wrap this with a read_lock(&tasklist_lock) to be safe, I > > > think. > > > > It will depend on the data accuracy. If the information on cpu usage is > very accurate then it becomes a way to analyse what is happening to > tasks you don't own - such as say cryptographic functions in the web > server... > > Otherwise, or with an owner check I see no real problem with the concept
So, is the following patch right ? I've added both the lock and the owner check...
Do you think it may be an interesting feature to be inserted in the kernel ?
Many thanks,
Claudio
diff --git a/kernel/sys.c b/kernel/sys.c --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1746,9 +1746,25 @@ int getrusage(struct task_struct *p, int
asmlinkage long sys_getrusage(int who, struct rusage __user *ru) { - if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN) - return -EINVAL; - return getrusage(current, who, ru); + if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN) { + struct task_struct* tsk; + struct rusage r; + read_lock(&tasklist_lock); + tsk = find_task_by_pid(who); + if (tsk == NULL) { + read_unlock(&tasklist_lock); + return -EINVAL; + } + if ((current->euid != tsk->euid) && + (current->euid != tsk->uid)) { + read_unlock(&tasklist_lock); + return -EINVAL; + } + k_getrusage(tsk, RUSAGE_SELF, &r); + read_unlock(&tasklist_lock); + return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0; + } else + return getrusage(current, who, ru); }
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