Pavel Emelyanov wrote: > We have one bit in the clone_flags left, so we won't be > able to create more namespaces after we make it busy. > Besides, for checkpoint/restart jobs we might want to > create tasks with pre-defined pids (virtual of course). > What else might be required from clone() - nobody knows. > > This is an attempt to create a extendable API for clone. > > I use the last bit in the clone_flags for CLONE_NEWCLONE. > When set it will denote that the child_tidptr is not a > pointer on the tid storage, but the pointer on the struct > long_clone_struct which currently looks like this: > > struct long_clone_arg { > int size; > }; > > When we want to add a new argument for clone we just put > it *at the end of this structure* and adjust the size. > The binary compatibility with older long_clone_arg-s is > facilitated with the clone_arg_has() macro. hmm, I wonder how lkml@ will react to this. do we have similar apis in the kernel ? > Sure, we lose the ability to clone tasks with extended > argument and the CLONE_CHILD_SETTID/CLEARTID, but do we > really need this? not in the extended clone flag version. I think. > The same thing is about to be done for unshare - we can > add the second argument for it and iff the CLONE_NEWCLONE > is specified - try to use it. Binary compatibility with > the old ushare will be kept. > > The new argument is pulled up to the create_new_namespaces > so that later we can easily use it w/o sending additional > patches. > > This is a final, but a pre-review patch for sys_clone() > that I plan to send to Andrew before we go on developing > new namespaces. > > Made against 2.6.24-rc5-mm1. The patch looks good and I compiled it and booted on x64 and x86_64. I think we should add the unshare support before sending to andrew and also add an extended flag array to show how it will be used. I have a mq_namespace patchset pending we could use for that and send all together ? C. > Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx> > > --- > > diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h > index 0e66b57..e01de56 100644 > --- a/include/linux/nsproxy.h > +++ b/include/linux/nsproxy.h > @@ -62,7 +62,8 @@ static inline struct nsproxy *task_nsproxy(struct task_struct *tsk) > return rcu_dereference(tsk->nsproxy); > } > > -int copy_namespaces(unsigned long flags, struct task_struct *tsk); > +int copy_namespaces(unsigned long flags, struct task_struct *tsk, > + struct long_clone_arg *carg); > void exit_task_namespaces(struct task_struct *tsk); > void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); > void free_nsproxy(struct nsproxy *ns); > diff --git a/include/linux/sched.h b/include/linux/sched.h > index e4d2a82..585a2b4 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -27,6 +27,23 @@ > #define CLONE_NEWUSER 0x10000000 /* New user namespace */ > #define CLONE_NEWPID 0x20000000 /* New pid namespace */ > #define CLONE_NEWNET 0x40000000 /* New network namespace */ > +#define CLONE_NEWCLONE 0x80000000 /* Has an long_clone_arg */ > + > +/* > + * If the CLONE_NEWCLONE argument is specified, then the > + * child_tidptr is expected to point to the struct long_clone_arg. > + * > + * This structure has a variable size, which is to be recorded > + * in the size member. All other members a to be put after this. > + * Never ... No. Always add new members only at its tail. > + * > + * The clone_arg_has() macro is responsible for checking whether > + * the given arg has the desired member. > + */ > + > +struct long_clone_arg { > + int size; > +}; > > /* > * Scheduling policies > @@ -40,6 +57,11 @@ > > #ifdef __KERNEL__ > > +#define clone_arg_has(arg, member) ({ \ > + struct long_clone_arg *__carg = arg; \ > + (__carg->size >= offsetof(struct long_clone_arg, member) + \ > + sizeof(__carg->member)); }) > + > struct sched_param { > int sched_priority; > }; > diff --git a/kernel/fork.c b/kernel/fork.c > index 8b558b7..f5895fc 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -967,6 +967,29 @@ static void rt_mutex_init_task(struct task_struct *p) > #endif > } > > +static struct long_clone_arg *get_long_clone_arg(int __user *child_tidptr) > +{ > + int size; > + struct long_clone_arg *carg; > + > + if (get_user(size, child_tidptr)) > + return ERR_PTR(-EFAULT); > + > + if (size > sizeof(struct long_clone_arg)) > + return ERR_PTR(-EINVAL); > + > + carg = kzalloc(sizeof(struct long_clone_arg), GFP_KERNEL); > + if (carg == NULL) > + return ERR_PTR(-ENOMEM); > + > + if (copy_from_user(carg, child_tidptr, size)) { > + kfree(carg); > + return ERR_PTR(-EFAULT); > + } > + > + return carg; > +} > + > /* > * This creates a new process as a copy of the old one, > * but does not actually start it yet. > @@ -985,6 +1008,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, > int retval; > struct task_struct *p; > int cgroup_callbacks_done = 0; > + struct long_clone_arg *carg = NULL; > > if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) > return ERR_PTR(-EINVAL); > @@ -1004,6 +1028,11 @@ static struct task_struct *copy_process(unsigned long clone_flags, > if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) > return ERR_PTR(-EINVAL); > > + if ((clone_flags & CLONE_NEWCLONE) && > + (clone_flags & (CLONE_CHILD_SETTID | > + CLONE_CHILD_CLEARTID))) > + return ERR_PTR(-EINVAL); > + > retval = security_task_create(clone_flags); > if (retval) > goto fork_out; > @@ -1132,8 +1161,15 @@ static struct task_struct *copy_process(unsigned long clone_flags, > /* Perform scheduler related setup. Assign this task to a CPU. */ > sched_fork(p, clone_flags); > > + if (clone_flags & CLONE_NEWCLONE) { > + carg = get_long_clone_arg(child_tidptr); > + retval = PTR_ERR(carg); > + if (IS_ERR(carg)) > + goto bad_fork_cleanup_policy; > + } > + > if ((retval = security_task_alloc(p))) > - goto bad_fork_cleanup_policy; > + goto bad_fork_cleanup_carg; > if ((retval = audit_alloc(p))) > goto bad_fork_cleanup_security; > /* copy all the process information */ > @@ -1151,7 +1187,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, > goto bad_fork_cleanup_signal; > if ((retval = copy_keys(clone_flags, p))) > goto bad_fork_cleanup_mm; > - if ((retval = copy_namespaces(clone_flags, p))) > + if ((retval = copy_namespaces(clone_flags, p, carg))) > goto bad_fork_cleanup_keys; > retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); > if (retval) > @@ -1345,6 +1381,8 @@ bad_fork_cleanup_audit: > audit_free(p); > bad_fork_cleanup_security: > security_task_free(p); > +bad_fork_cleanup_carg: > + kfree(carg); > bad_fork_cleanup_policy: > #ifdef CONFIG_NUMA > mpol_free(p->mempolicy); > diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c > index f5d332c..b955196 100644 > --- a/kernel/nsproxy.c > +++ b/kernel/nsproxy.c > @@ -48,7 +48,8 @@ static inline struct nsproxy *clone_nsproxy(struct nsproxy *orig) > * leave it to the caller to do proper locking and attach it to task. > */ > static struct nsproxy *create_new_namespaces(unsigned long flags, > - struct task_struct *tsk, struct fs_struct *new_fs) > + struct task_struct *tsk, struct fs_struct *new_fs, > + struct long_clone_arg *carg) > { > struct nsproxy *new_nsp; > int err; > @@ -119,7 +120,8 @@ out_ns: > * called from clone. This now handles copy for nsproxy and all > * namespaces therein. > */ > -int copy_namespaces(unsigned long flags, struct task_struct *tsk) > +int copy_namespaces(unsigned long flags, struct task_struct *tsk, > + struct long_clone_arg *carg) > { > struct nsproxy *old_ns = tsk->nsproxy; > struct nsproxy *new_ns; > @@ -131,7 +133,8 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) > get_nsproxy(old_ns); > > if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | > - CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWNET))) > + CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWNET | > + CLONE_NEWCLONE))) > return 0; > > if (!capable(CAP_SYS_ADMIN)) { > @@ -139,7 +142,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) > goto out; > } > > - new_ns = create_new_namespaces(flags, tsk, tsk->fs); > + new_ns = create_new_namespaces(flags, tsk, tsk->fs, carg); > if (IS_ERR(new_ns)) { > err = PTR_ERR(new_ns); > goto out; > @@ -191,7 +194,7 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags, > return -EPERM; > > *new_nsp = create_new_namespaces(unshare_flags, current, > - new_fs ? new_fs : current->fs); > + new_fs ? new_fs : current->fs, NULL); > if (IS_ERR(*new_nsp)) { > err = PTR_ERR(*new_nsp); > goto out; _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers