1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/core/netclassid_cgroup.c Classid Cgroupfs Handling
4 *
5 * Authors: Thomas Graf <tgraf@suug.ch>
6 */
7
8 #include <linux/slab.h>
9 #include <linux/cgroup.h>
10 #include <linux/fdtable.h>
11 #include <linux/sched/task.h>
12
13 #include <net/cls_cgroup.h>
14 #include <net/sock.h>
15
css_cls_state(struct cgroup_subsys_state * css)16 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
17 {
18 return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
19 }
20
task_cls_state(struct task_struct * p)21 struct cgroup_cls_state *task_cls_state(struct task_struct *p)
22 {
23 return css_cls_state(task_css_check(p, net_cls_cgrp_id,
24 rcu_read_lock_held() ||
25 rcu_read_lock_bh_held() ||
26 rcu_read_lock_trace_held()));
27 }
28 EXPORT_SYMBOL_GPL(task_cls_state);
29
30 static struct cgroup_subsys_state *
cgrp_css_alloc(struct cgroup_subsys_state * parent_css)31 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
32 {
33 struct cgroup_cls_state *cs;
34
35 cs = kzalloc(sizeof(*cs), GFP_KERNEL);
36 if (!cs)
37 return ERR_PTR(-ENOMEM);
38
39 return &cs->css;
40 }
41
cgrp_css_online(struct cgroup_subsys_state * css)42 static int cgrp_css_online(struct cgroup_subsys_state *css)
43 {
44 struct cgroup_cls_state *cs = css_cls_state(css);
45 struct cgroup_cls_state *parent = css_cls_state(css->parent);
46
47 if (parent)
48 cs->classid = parent->classid;
49
50 return 0;
51 }
52
cgrp_css_free(struct cgroup_subsys_state * css)53 static void cgrp_css_free(struct cgroup_subsys_state *css)
54 {
55 kfree(css_cls_state(css));
56 }
57
58 /*
59 * To avoid freezing of sockets creation for tasks with big number of threads
60 * and opened sockets lets release file_lock every 1000 iterated descriptors.
61 * New sockets will already have been created with new classid.
62 */
63
64 struct update_classid_context {
65 u32 classid;
66 unsigned int batch;
67 };
68
69 #define UPDATE_CLASSID_BATCH 1000
70
update_classid_sock(const void * v,struct file * file,unsigned int n)71 static int update_classid_sock(const void *v, struct file *file, unsigned int n)
72 {
73 struct update_classid_context *ctx = (void *)v;
74 struct socket *sock = sock_from_file(file);
75
76 if (sock)
77 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid);
78 if (--ctx->batch == 0) {
79 ctx->batch = UPDATE_CLASSID_BATCH;
80 return n + 1;
81 }
82 return 0;
83 }
84
update_classid_task(struct task_struct * p,u32 classid)85 static void update_classid_task(struct task_struct *p, u32 classid)
86 {
87 struct update_classid_context ctx = {
88 .classid = classid,
89 .batch = UPDATE_CLASSID_BATCH
90 };
91 unsigned int fd = 0;
92
93 /* Only update the leader task, when many threads in this task,
94 * so it can avoid the useless traversal.
95 */
96 if (p != p->group_leader)
97 return;
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 cs->classid = (u32)value;
130
131 css_task_iter_start(css, 0, &it);
132 while ((p = css_task_iter_next(&it)))
133 update_classid_task(p, cs->classid);
134 css_task_iter_end(&it);
135
136 return 0;
137 }
138
139 static struct cftype ss_files[] = {
140 {
141 .name = "classid",
142 .read_u64 = read_classid,
143 .write_u64 = write_classid,
144 },
145 { } /* terminate */
146 };
147
148 struct cgroup_subsys net_cls_cgrp_subsys = {
149 .css_alloc = cgrp_css_alloc,
150 .css_online = cgrp_css_online,
151 .css_free = cgrp_css_free,
152 .attach = cgrp_attach,
153 .legacy_cftypes = ss_files,
154 };
155