From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> Date: Wed, 24 Dec 2008 13:46:02 -0800 Subject: [PATCH 3/6][v5] Define siginfo_from_ancestor_ns() Determine if sender of a signal is from an ancestor namespace. This function will be used in a follow-on patch. This is based on discussions on the patch from Oleg Nesterov and me http://lkml.org/lkml/2008/11/25/462. Changelog[v5]: - (Oleg Nesterov) Put siginfo_from_ancestor_ns() back under CONFIG_PID_NS. - (Oleg Nesterov) Remove the warning in rt_sigqueueinfo(). Changelog[v4]: - siginfo_from_ancestor_ns() is fairly clean and it does not need to be under CONFIG_PID_NS. Only siginfo_from_user() needs to be. - Warn if rt_sigqueueinfo() uses SI_ASYNCIO. - Added a check for pid-ns of receiver being NULL (in case it is exiting). Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> --- kernel/signal.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 56 insertions(+), 0 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 30b9c5c..f33100d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -820,6 +820,61 @@ static inline int legacy_queue(struct sigpending *signals, int sig) { return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); } +/* + * Return 1 if this signal originated directly from a user process (i.e via + * kill(), tkill(), sigqueue()). Return 0 otherwise. + * + * TODO: + * To make this less hacky, make SI_ASYNCIO a kernel signal. + */ +#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; +} + +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. + * (We maybe called from interrupt context and dereferencing + * pid namespace would be safe). + */ + if (siginfo_from_user(info)) { + /* + * If we do not have a pid in the receiver's namespace, + * we must be from an ancestor namespace. + * + * Note: + * If receiver is exiting, ns == NULL, signal will be + * queued but eventually ignored anyway (wants_signal() + * is FALSE). Assume here that signal is from ancestor + * namespace and queue the signal. + */ + ns = task_active_pid_ns(t); + if (!ns || task_pid_nr_ns(current, ns) <= 0) + return 1; + } + + return 0; +} + +#else + +static inline int siginfo_from_ancestor_ns(struct task_struct *t, + siginfo_t *info) +{ + return 0; +} + +#endif static int send_signal(int sig, struct siginfo *info, struct task_struct *t, int group) @@ -2324,6 +2379,7 @@ 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; + info.si_signo = sig; /* POSIX.1b doesn't mention process groups. */ -- 1.5.2.5 _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers