Sukadev Bhattiprolu wrote:
> From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
> Date: Mon, 4 May 2009 01:17:45 -0700
> Subject: [PATCH 7/7] [PATCH] Define clone_with_pids syscall
>
> clone_with_pids() is same as clone(), except that it takes a 'target_pid_set'
> paramter which lets caller choose a specific pid number for the child process
> in each of the child process's pid namespace. This system call would be needed
> to implement Checkpoint/Restart (i.e after a checkpoint, restart a process with
> its original pids).
>
> Call clone_with_pids as follows:
>
> pid_t pids[] = { 0, 77, 99 };
> struct target_pid_set pid_set;
>
> pid_set.num_pids = sizeof(pids) / sizeof(int);
> pid_set.target_pids = &pids;
>
> syscall(__NR_clone_with_pids, flags, stack, NULL, NULL, NULL, &pid_set);
>
> If a target-pid is 0, the kernel continues to assign a pid for the process in
> that namespace. In the above example, pids[0] is 0, meaning the kernel will
> assign next available pid to the process in init_pid_ns. But kernel will assign
> pid 77 in the child pid namespace 1 and pid 99 in pid namespace 2. If either
> 77 or 99 are taken, the system call fails with -EBUSY.
>
> If 'pid_set.num_pids' exceeds the current nesting level of pid namespaces,
> the system call fails with -EINVAL.
>
> Its mostly an exploratory patch seeking feedback on the interface.
>
> NOTE:
> Compared to clone(), clone_with_pids() needs to pass in two more
> pieces of information:
>
> - number of pids in the set
> - user buffer containing the list of pids.
>
> But since clone() already takes 5 parameters, use a 'struct
> target_pid_set'.
>
> TODO:
> - Gently tested.
> - May need additional sanity checks in check_target_pids()
> - Allow CLONE_NEWPID() with clone_with_pids() (ensure target-pid in
> the namespace is either 1 or 0).
>
> Changelog[v1]:
> - Fixed some compile errors (had fixed these errors earlier in my
> git tree but had not refreshed patches before emailing them)
>
> Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
> ---
Reviewed-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
but ...
[...]
> +static pid_t *copy_target_pids(unsigned long clone_flags, void __user *upid_setp)
> +{
> + int rc;
> + int size;
> + pid_t __user *utarget_pids;
> + pid_t *target_pids;
> + struct target_pid_set pid_set;
> +
> + if (copy_from_user(&pid_set, upid_setp, sizeof(pid_set)))
> + return ERR_PTR(-EFAULT);
> +
> + size = pid_set.num_pids * sizeof(pid_t);
...either test "pid_set.num_pids > 0" (and give -EINVAL),
or...
[...]
>
> +struct target_pid_set {
> + int num_pids;
... make this 'size_t' ?
> + pid_t *target_pids;
> +};
> +
> #endif /* __KERNEL__ */
> #endif /* __ASSEMBLY__ */
> #endif /* _LINUX_TYPES_H */
_______________________________________________
Containers mailing list
Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/containers
