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_bh_held()));
25 }
26 EXPORT_SYMBOL_GPL(task_cls_state);
27
28 static struct cgroup_subsys_state *
cgrp_css_alloc(struct cgroup_subsys_state * parent_css)29 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
30 {
31 struct cgroup_cls_state *cs;
32
33 cs = kzalloc(sizeof(*cs), GFP_KERNEL);
34 if (!cs)
35 return ERR_PTR(-ENOMEM);
36
37 return &cs->css;
38 }
39
cgrp_css_online(struct cgroup_subsys_state * css)40 static int cgrp_css_online(struct cgroup_subsys_state *css)
41 {
42 struct cgroup_cls_state *cs = css_cls_state(css);
43 struct cgroup_cls_state *parent = css_cls_state(css->parent);
44
45 if (parent)
46 cs->classid = parent->classid;
47
48 return 0;
49 }
50
cgrp_css_free(struct cgroup_subsys_state * css)51 static void cgrp_css_free(struct cgroup_subsys_state *css)
52 {
53 kfree(css_cls_state(css));
54 }
55
56 /*
57 * To avoid freezing of sockets creation for tasks with big number of threads
58 * and opened sockets lets release file_lock every 1000 iterated descriptors.
59 * New sockets will already have been created with new classid.
60 */
61
62 struct update_classid_context {
63 u32 classid;
64 unsigned int batch;
65 };
66
67 #define UPDATE_CLASSID_BATCH 1000
68
update_classid_sock(const void * v,struct file * file,unsigned n)69 static int update_classid_sock(const void *v, struct file *file, unsigned n)
70 {
71 struct update_classid_context *ctx = (void *)v;
72 struct socket *sock = sock_from_file(file);
73
74 if (sock)
75 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid);
76 if (--ctx->batch == 0) {
77 ctx->batch = UPDATE_CLASSID_BATCH;
78 return n + 1;
79 }
80 return 0;
81 }
82
update_classid_task(struct task_struct * p,u32 classid)83 static void update_classid_task(struct task_struct *p, u32 classid)
84 {
85 struct update_classid_context ctx = {
86 .classid = classid,
87 .batch = UPDATE_CLASSID_BATCH
88 };
89 unsigned int fd = 0;
90
91 do {
92 task_lock(p);
93 fd = iterate_fd(p->files, fd, update_classid_sock, &ctx);
94 task_unlock(p);
95 cond_resched();
96 } while (fd);
97 }
98
cgrp_attach(struct cgroup_taskset * tset)99 static void cgrp_attach(struct cgroup_taskset *tset)
100 {
101 struct cgroup_subsys_state *css;
102 struct task_struct *p;
103
104 cgroup_taskset_for_each(p, css, tset) {
105 update_classid_task(p, css_cls_state(css)->classid);
106 }
107 }
108
read_classid(struct cgroup_subsys_state * css,struct cftype * cft)109 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
110 {
111 return css_cls_state(css)->classid;
112 }
113
write_classid(struct cgroup_subsys_state * css,struct cftype * cft,u64 value)114 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
115 u64 value)
116 {
117 struct cgroup_cls_state *cs = css_cls_state(css);
118 struct css_task_iter it;
119 struct task_struct *p;
120
121 cs->classid = (u32)value;
122
123 css_task_iter_start(css, 0, &it);
124 while ((p = css_task_iter_next(&it)))
125 update_classid_task(p, cs->classid);
126 css_task_iter_end(&it);
127
128 return 0;
129 }
130
131 static struct cftype ss_files[] = {
132 {
133 .name = "classid",
134 .read_u64 = read_classid,
135 .write_u64 = write_classid,
136 },
137 { } /* terminate */
138 };
139
140 struct cgroup_subsys net_cls_cgrp_subsys = {
141 .css_alloc = cgrp_css_alloc,
142 .css_online = cgrp_css_online,
143 .css_free = cgrp_css_free,
144 .attach = cgrp_attach,
145 .legacy_cftypes = ss_files,
146 };
147
