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sys_clone: add a comment about CLONE_PTRACE and CLONE_UNTRACED

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Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko 2013-06-28 18:57:27 +02:00
parent 44a6d04e5e
commit d083016e03
1 changed files with 12 additions and 0 deletions
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12
process.c
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@ -569,6 +569,18 @@ sys_clone(struct tcb *tcp)
if (flags & (CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID))
tprintf(", child_tidptr=%#lx", tcp->u_arg[ARG_CTID]);
}
/* TODO on syscall entry:
* We can clear CLONE_PTRACE here since it is an ancient hack
* to allow us to catch children, and we use another hack for that.
* But CLONE_PTRACE can conceivably be used by malicious programs
* to subvert us. By clearing this bit, we can defend against it:
* in untraced execution, CLONE_PTRACE should have no effect.
*
* We can also clear CLONE_UNTRACED, since it allows to start
* children outside of our control. At the moment
* I'm trying to figure out whether there is a *legitimate*
* use of this flag which we should respect.
*/
return 0;
}