Messages in this thread Patch in this message | | | Date | Wed, 24 Dec 2008 17:28:23 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC][PATCH 3/7][v4] Define siginfo_from_ancestor_ns() |
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On 12/24, Sukadev Bhattiprolu wrote: > > +#ifdef CONFIG_PID_NS > +static inline int siginfo_from_user(siginfo_t *info) > +{ > + if (!is_si_special(info) && SI_FROMUSER(info) && > + info->si_code != SI_ASYNCIO) > + return 1; > + > + return 0; > +} > +#else > +static inline int siginfo_from_user(siginfo_t *info) > +{ > + return 0; > +} > +#endif > + > +static inline int siginfo_from_ancestor_ns(struct task_struct *t, > + siginfo_t *info) > +{ > + struct pid_namespace *ns; > + > + /* > + * Ensure signal is from user-space before checking pid namespace > + */ > + if (siginfo_from_user(info)) { > + /* > + * If we do not have a pid in the receiver's namespace, > + * we must be an ancestor of the receiver. > + * > + * CHECK: > + * If receiver is exiting, ns == NULL, signal will be > + * queued but ignored (wants_signal() is FALSES). For > + * compatibility with current behavior, assume it is > + * from ancestor and queue the signal anyway ? > + */ > + ns = task_active_pid_ns(t); > + if (!ns || task_pid_nr_ns(current, ns) <= 0) > + return 1; > + } > + > + return 0; > +}
Small nit... siginfo_from_user() is only called by siginfo_from_ancestor_ns(). The first helper depends on CONFIG_PID_NS, the second is not. A bit strange.
Isn't it cleaner to do
#ifdef CONFIG_PID_NS static inline int siginfo_from_user(siginfo_t *info) { ... } static inline int siginfo_from_ancestor_ns(...) { ... } #else static inline int siginfo_from_ancestor_ns(...) { return 0; } #endif
?
> +#ifdef CONFIG_PID_NS > +/* > + * siginfo_from_user() assumes that si_code SI_ASYNCIO comes only from > + * within the kernel. If an application is passing in SI_ASYNCIO we > + * want to know about it. > + */ > +static void warn_on_asyncio(siginfo_t *info) > +{ > + WARN_ON_ONCE(info->si_code == SI_ASYNCIO); > +} > +#else > +#define warn_on_asyncio(info) {} > +#endif > + > asmlinkage long > sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo) > { > @@ -2324,6 +2388,9 @@ sys_rt_sigqueueinfo(pid_t pid, int sig, siginfo_t __user *uinfo) > Nor can they impersonate a kill(), which adds source info. */ > if (info.si_code >= 0) > return -EPERM; > + > + warn_on_asyncio(&info);
Hmm... why do you want this? The user-space can use any si_code >= 0, why should we uglify the code?
And, SI_ASYNCIO only matters when we send the signal to the subnamespace, and in that case we will probably mangle .si_pid. So why don't we warn when .si_code == SI_USER?
Oleg.
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