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 int err;
72 struct update_classid_context *ctx = (void *)v;
73 struct socket *sock = sock_from_file(file, &err);
74
75 if (sock)
76 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid);
77 if (--ctx->batch == 0) {
78 ctx->batch = UPDATE_CLASSID_BATCH;
79 return n + 1;
80 }
81 return 0;
82 }
83
update_classid_task(struct task_struct * p,u32 classid)84 static void update_classid_task(struct task_struct *p, u32 classid)
85 {
86 struct update_classid_context ctx = {
87 .classid = classid,
88 .batch = UPDATE_CLASSID_BATCH
89 };
90 unsigned int fd = 0;
91
92 do {
93 task_lock(p);
94 fd = iterate_fd(p->files, fd, update_classid_sock, &ctx);
95 task_unlock(p);
96 cond_resched();
97 } while (fd);
98 }
99
cgrp_attach(struct cgroup_taskset * tset)100 static void cgrp_attach(struct cgroup_taskset *tset)
101 {
102 struct cgroup_subsys_state *css;
103 struct task_struct *p;
104
105 cgroup_taskset_for_each(p, css, tset) {
106 update_classid_task(p, css_cls_state(css)->classid);
107 }
108 }
109
read_classid(struct cgroup_subsys_state * css,struct cftype * cft)110 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
111 {
112 return css_cls_state(css)->classid;
113 }
114
write_classid(struct cgroup_subsys_state * css,struct cftype * cft,u64 value)115 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
116 u64 value)
117 {
118 struct cgroup_cls_state *cs = css_cls_state(css);
119 struct css_task_iter it;
120 struct task_struct *p;
121
122 cs->classid = (u32)value;
123
124 css_task_iter_start(css, 0, &it);
125 while ((p = css_task_iter_next(&it)))
126 update_classid_task(p, cs->classid);
127 css_task_iter_end(&it);
128
129 return 0;
130 }
131
132 static struct cftype ss_files[] = {
133 {
134 .name = "classid",
135 .read_u64 = read_classid,
136 .write_u64 = write_classid,
137 },
138 { } /* terminate */
139 };
140
141 struct cgroup_subsys net_cls_cgrp_subsys = {
142 .css_alloc = cgrp_css_alloc,
143 .css_online = cgrp_css_online,
144 .css_free = cgrp_css_free,
145 .attach = cgrp_attach,
146 .legacy_cftypes = ss_files,
147 };
148