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https://github.com/torvalds/linux
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3b13758f51
The classid of a process is changed either when a process is moved to or from a cgroup or when the net_cls.classid file is updated. Previously net_cls only supported propogating these changes to the cgroup's related sockets when a process was added or removed from the cgroup. This means it was neccessary to remove and re-add all processes to a cgroup in order to update its classid. This change introduces support for doing this dynamically - i.e. when the value is changed in the net_cls_classid file, this will also trigger an update to the classid associated with all sockets controlled by the cgroup. This mimics the behaviour of other cgroup subsystems. net_prio circumvents this issue by storing an index into a table with each socket (and so any updates to the table, don't require updating the value associated with the socket). net_cls, however, passes the socket the classid directly, and so this additional step is needed. Signed-off-by: Nina Schiff <ninasc@fb.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
122 lines
2.8 KiB
C
122 lines
2.8 KiB
C
/*
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* net/core/netclassid_cgroup.c Classid Cgroupfs Handling
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Thomas Graf <tgraf@suug.ch>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/cgroup.h>
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#include <linux/fdtable.h>
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#include <net/cls_cgroup.h>
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#include <net/sock.h>
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static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
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{
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return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
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}
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struct cgroup_cls_state *task_cls_state(struct task_struct *p)
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{
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return css_cls_state(task_css_check(p, net_cls_cgrp_id,
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rcu_read_lock_bh_held()));
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}
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EXPORT_SYMBOL_GPL(task_cls_state);
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static struct cgroup_subsys_state *
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cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
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{
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struct cgroup_cls_state *cs;
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cs = kzalloc(sizeof(*cs), GFP_KERNEL);
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if (!cs)
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return ERR_PTR(-ENOMEM);
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return &cs->css;
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}
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static int cgrp_css_online(struct cgroup_subsys_state *css)
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{
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struct cgroup_cls_state *cs = css_cls_state(css);
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struct cgroup_cls_state *parent = css_cls_state(css->parent);
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if (parent)
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cs->classid = parent->classid;
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return 0;
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}
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static void cgrp_css_free(struct cgroup_subsys_state *css)
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{
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kfree(css_cls_state(css));
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}
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static int update_classid_sock(const void *v, struct file *file, unsigned n)
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{
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int err;
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struct socket *sock = sock_from_file(file, &err);
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if (sock)
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sock->sk->sk_classid = (u32)(unsigned long)v;
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return 0;
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}
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static void update_classid(struct cgroup_subsys_state *css, void *v)
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{
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struct css_task_iter it;
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struct task_struct *p;
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css_task_iter_start(css, &it);
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while ((p = css_task_iter_next(&it))) {
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task_lock(p);
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iterate_fd(p->files, 0, update_classid_sock, v);
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task_unlock(p);
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}
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css_task_iter_end(&it);
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}
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static void cgrp_attach(struct cgroup_subsys_state *css,
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struct cgroup_taskset *tset)
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{
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update_classid(css,
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(void *)(unsigned long)css_cls_state(css)->classid);
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}
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static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
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{
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return css_cls_state(css)->classid;
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}
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static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
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u64 value)
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{
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struct cgroup_cls_state *cs = css_cls_state(css);
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cs->classid = (u32)value;
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update_classid(css, (void *)(unsigned long)cs->classid);
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return 0;
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}
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static struct cftype ss_files[] = {
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{
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.name = "classid",
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.read_u64 = read_classid,
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.write_u64 = write_classid,
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},
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{ } /* terminate */
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};
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struct cgroup_subsys net_cls_cgrp_subsys = {
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.css_alloc = cgrp_css_alloc,
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.css_online = cgrp_css_online,
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.css_free = cgrp_css_free,
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.attach = cgrp_attach,
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.legacy_cftypes = ss_files,
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};
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