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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/core/netclassid_cgroup.c Classid Cgroupfs Handling
*
* Authors: Thomas Graf <tgraf@suug.ch>
*/
#include <linux/slab.h>
#include <linux/cgroup.h>
#include <linux/fdtable.h>
#include <linux/sched/task.h>
#include <net/cls_cgroup.h>
#include <net/sock.h>
static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
{
return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
}
struct cgroup_cls_state *task_cls_state(struct task_struct *p)
{
return css_cls_state(task_css_check(p, net_cls_cgrp_id,
rcu_read_lock_bh_held()));
}
EXPORT_SYMBOL_GPL(task_cls_state);
static struct cgroup_subsys_state *
cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct cgroup_cls_state *cs;
cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return ERR_PTR(-ENOMEM);
return &cs->css;
}
static int cgrp_css_online(struct cgroup_subsys_state *css)
{
struct cgroup_cls_state *cs = css_cls_state(css);
struct cgroup_cls_state *parent = css_cls_state(css->parent);
if (parent)
cs->classid = parent->classid;
return 0;
}
static void cgrp_css_free(struct cgroup_subsys_state *css)
{
kfree(css_cls_state(css));
}
/*
* To avoid freezing of sockets creation for tasks with big number of threads
* and opened sockets lets release file_lock every 1000 iterated descriptors.
* New sockets will already have been created with new classid.
*/
struct update_classid_context {
u32 classid;
unsigned int batch;
};
#define UPDATE_CLASSID_BATCH 1000
static int update_classid_sock(const void *v, struct file *file, unsigned int n)
{
struct update_classid_context *ctx = (void *)v;
struct socket *sock = sock_from_file(file);
if (sock)
sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid);
if (--ctx->batch == 0) {
ctx->batch = UPDATE_CLASSID_BATCH;
return n + 1;
}
return 0;
}
static void update_classid_task(struct task_struct *p, u32 classid)
{
struct update_classid_context ctx = {
.classid = classid,
.batch = UPDATE_CLASSID_BATCH
};
unsigned int fd = 0;
/* Only update the leader task, when many threads in this task,
* so it can avoid the useless traversal.
*/
if (p != p->group_leader)
return;
do {
task_lock(p);
fd = iterate_fd(p->files, fd, update_classid_sock, &ctx);
task_unlock(p);
cond_resched();
} while (fd);
}
static void cgrp_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
struct task_struct *p;
cgroup_taskset_for_each(p, css, tset) {
update_classid_task(p, css_cls_state(css)->classid);
}
}
static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
{
return css_cls_state(css)->classid;
}
static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
u64 value)
{
struct cgroup_cls_state *cs = css_cls_state(css);
struct css_task_iter it;
struct task_struct *p;
cs->classid = (u32)value;
css_task_iter_start(css, 0, &it);
while ((p = css_task_iter_next(&it)))
update_classid_task(p, cs->classid);
css_task_iter_end(&it);
return 0;
}
static struct cftype ss_files[] = {
{
.name = "classid",
.read_u64 = read_classid,
.write_u64 = write_classid,
},
{ } /* terminate */
};
struct cgroup_subsys net_cls_cgrp_subsys = {
.css_alloc = cgrp_css_alloc,
.css_online = cgrp_css_online,
.css_free = cgrp_css_free,
.attach = cgrp_attach,
.legacy_cftypes = ss_files,
};
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