From: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> Date: Sat, 20 Dec 2008 12:19:29 -0800 Subject: [RFC][PATCH 4/6][v3] 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 an early/lightly tested RFC patch. Would it be safe to implement siginfo_from_user() as below and then use it dereference the pid namespace of sender ? This is based on discussions on the patch from Oleg Nesterov and me http://lkml.org/lkml/2008/11/25/462. Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> --- kernel/signal.c | 41 +++++++++++++++++++++++++++++++++++++++++ 1 files changed, 41 insertions(+), 0 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 55f41b6..058b4c0 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -820,6 +820,47 @@ 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: + * Making SI_ASYNCIO a kernel signal could make this less hacky. + */ +#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) +{ + /* + * 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. + */ + if (task_pid_nr_ns(current, task_active_pid_ns(t)) <= 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) -- 1.5.2.5 _______________________________________________ Containers mailing list contain...@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list Devel@openvz.org https://openvz.org/mailman/listinfo/devel
