1 /*
2 * net/core/netclassid_cgroup.c Classid Cgroupfs Handling
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * Authors: Thomas Graf <tgraf@suug.ch>
10 */
11
12 #include <linux/slab.h>
13 #include <linux/cgroup.h>
14 #include <linux/fdtable.h>
15 #include <linux/sched/task.h>
16
17 #include <net/cls_cgroup.h>
18 #include <net/sock.h>
19
css_cls_state(struct cgroup_subsys_state * css)20 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
21 {
22 return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
23 }
24
task_cls_state(struct task_struct * p)25 struct cgroup_cls_state *task_cls_state(struct task_struct *p)
26 {
27 return css_cls_state(task_css_check(p, net_cls_cgrp_id,
28 rcu_read_lock_bh_held()));
29 }
30 EXPORT_SYMBOL_GPL(task_cls_state);
31
32 static struct cgroup_subsys_state *
cgrp_css_alloc(struct cgroup_subsys_state * parent_css)33 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
34 {
35 struct cgroup_cls_state *cs;
36
37 cs = kzalloc(sizeof(*cs), GFP_KERNEL);
38 if (!cs)
39 return ERR_PTR(-ENOMEM);
40
41 return &cs->css;
42 }
43
cgrp_css_online(struct cgroup_subsys_state * css)44 static int cgrp_css_online(struct cgroup_subsys_state *css)
45 {
46 struct cgroup_cls_state *cs = css_cls_state(css);
47 struct cgroup_cls_state *parent = css_cls_state(css->parent);
48
49 if (parent)
50 cs->classid = parent->classid;
51
52 return 0;
53 }
54
cgrp_css_free(struct cgroup_subsys_state * css)55 static void cgrp_css_free(struct cgroup_subsys_state *css)
56 {
57 kfree(css_cls_state(css));
58 }
59
60 /*
61 * To avoid freezing of sockets creation for tasks with big number of threads
62 * and opened sockets lets release file_lock every 1000 iterated descriptors.
63 * New sockets will already have been created with new classid.
64 */
65
66 struct update_classid_context {
67 u32 classid;
68 unsigned int batch;
69 };
70
71 #define UPDATE_CLASSID_BATCH 1000
72
update_classid_sock(const void * v,struct file * file,unsigned n)73 static int update_classid_sock(const void *v, struct file *file, unsigned n)
74 {
75 int err;
76 struct update_classid_context *ctx = (void *)v;
77 struct socket *sock = sock_from_file(file, &err);
78
79 if (sock) {
80 spin_lock(&cgroup_sk_update_lock);
81 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid);
82 spin_unlock(&cgroup_sk_update_lock);
83 }
84 if (--ctx->batch == 0) {
85 ctx->batch = UPDATE_CLASSID_BATCH;
86 return n + 1;
87 }
88 return 0;
89 }
90
update_classid_task(struct task_struct * p,u32 classid)91 static void update_classid_task(struct task_struct *p, u32 classid)
92 {
93 struct update_classid_context ctx = {
94 .classid = classid,
95 .batch = UPDATE_CLASSID_BATCH
96 };
97 unsigned int fd = 0;
98
99 do {
100 task_lock(p);
101 fd = iterate_fd(p->files, fd, update_classid_sock, &ctx);
102 task_unlock(p);
103 cond_resched();
104 } while (fd);
105 }
106
cgrp_attach(struct cgroup_taskset * tset)107 static void cgrp_attach(struct cgroup_taskset *tset)
108 {
109 struct cgroup_subsys_state *css;
110 struct task_struct *p;
111
112 cgroup_taskset_for_each(p, css, tset) {
113 update_classid_task(p, css_cls_state(css)->classid);
114 }
115 }
116
read_classid(struct cgroup_subsys_state * css,struct cftype * cft)117 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
118 {
119 return css_cls_state(css)->classid;
120 }
121
write_classid(struct cgroup_subsys_state * css,struct cftype * cft,u64 value)122 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
123 u64 value)
124 {
125 struct cgroup_cls_state *cs = css_cls_state(css);
126 struct css_task_iter it;
127 struct task_struct *p;
128
129 cgroup_sk_alloc_disable();
130
131 cs->classid = (u32)value;
132
133 css_task_iter_start(css, 0, &it);
134 while ((p = css_task_iter_next(&it))) {
135 update_classid_task(p, cs->classid);
136 cond_resched();
137 }
138 css_task_iter_end(&it);
139
140 return 0;
141 }
142
143 static struct cftype ss_files[] = {
144 {
145 .name = "classid",
146 .read_u64 = read_classid,
147 .write_u64 = write_classid,
148 },
149 { } /* terminate */
150 };
151
152 struct cgroup_subsys net_cls_cgrp_subsys = {
153 .css_alloc = cgrp_css_alloc,
154 .css_online = cgrp_css_online,
155 .css_free = cgrp_css_free,
156 .attach = cgrp_attach,
157 .legacy_cftypes = ss_files,
158 };
159