Messages in this thread Patch in this message | | | Date | Wed, 18 Feb 2009 14:28:57 -0800 | From | Greg KH <> | Subject | [patch 01/36] pid: implement ns_of_pid |
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2.6.27-stable review patch. If anyone has any objections, please let us know.
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From: Eric W. Biederman <ebiederm@xmission.com>
commit f9fb860f67b9542cd78d1558dec7058092b57d8e upstream.
A current problem with the pid namespace is that it is easy to do pid related work after exit_task_namespaces which drops the nsproxy pointer.
However if we are doing pid namespace related work we are always operating on some struct pid which retains the pid_namespace pointer of the pid namespace it was allocated in.
So provide ns_of_pid which allows us to find the pid namespace a pid was allocated in.
Using this we have the needed infrastructure to do pid namespace related work at anytime we have a struct pid, removing the chance of accidentally having a NULL pointer dereference when accessing current->nsproxy.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com> Cc: Bastian Blank <bastian@waldi.eu.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Nadia Derbey <Nadia.Derbey@bull.net> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- include/linux/pid.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
--- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -123,6 +123,24 @@ extern struct pid *alloc_pid(struct pid_ extern void free_pid(struct pid *pid); /* + * ns_of_pid() returns the pid namespace in which the specified pid was + * allocated. + * + * NOTE: + * ns_of_pid() is expected to be called for a process (task) that has + * an attached 'struct pid' (see attach_pid(), detach_pid()) i.e @pid + * is expected to be non-NULL. If @pid is NULL, caller should handle + * the resulting NULL pid-ns. + */ +static inline struct pid_namespace *ns_of_pid(struct pid *pid) +{ + struct pid_namespace *ns = NULL; + if (pid) + ns = pid->numbers[pid->level].ns; + return ns; +} + +/* * the helpers to get the pid's id seen from different namespaces * * pid_nr() : global id, i.e. the id seen from the init namespace;
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