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 | |
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 | |
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 * |
29 | cgrp_css_alloc(struct cgroup_subsys_state *parent_css) |
30 | { |
31 | struct cgroup_cls_state *cs; |
32 | |
33 | cs = kzalloc(size: sizeof(*cs), GFP_KERNEL); |
34 | if (!cs) |
35 | return ERR_PTR(error: -ENOMEM); |
36 | |
37 | return &cs->css; |
38 | } |
39 | |
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: css->parent); |
44 | |
45 | if (parent) |
46 | cs->classid = parent->classid; |
47 | |
48 | return 0; |
49 | } |
50 | |
51 | static void cgrp_css_free(struct cgroup_subsys_state *css) |
52 | { |
53 | kfree(objp: 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 | |
69 | static int update_classid_sock(const void *v, struct file *file, unsigned int 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(skcd: &sock->sk->sk_cgrp_data, classid: ctx->classid); |
76 | if (--ctx->batch == 0) { |
77 | ctx->batch = UPDATE_CLASSID_BATCH; |
78 | return n + 1; |
79 | } |
80 | return 0; |
81 | } |
82 | |
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 | /* Only update the leader task, when many threads in this task, |
92 | * so it can avoid the useless traversal. |
93 | */ |
94 | if (p != p->group_leader) |
95 | return; |
96 | |
97 | do { |
98 | task_lock(p); |
99 | fd = iterate_fd(p->files, fd, update_classid_sock, &ctx); |
100 | task_unlock(p); |
101 | cond_resched(); |
102 | } while (fd); |
103 | } |
104 | |
105 | static void cgrp_attach(struct cgroup_taskset *tset) |
106 | { |
107 | struct cgroup_subsys_state *css; |
108 | struct task_struct *p; |
109 | |
110 | cgroup_taskset_for_each(p, css, tset) { |
111 | update_classid_task(p, classid: css_cls_state(css)->classid); |
112 | } |
113 | } |
114 | |
115 | static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft) |
116 | { |
117 | return css_cls_state(css)->classid; |
118 | } |
119 | |
120 | static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft, |
121 | u64 value) |
122 | { |
123 | struct cgroup_cls_state *cs = css_cls_state(css); |
124 | struct css_task_iter it; |
125 | struct task_struct *p; |
126 | |
127 | cs->classid = (u32)value; |
128 | |
129 | css_task_iter_start(css, flags: 0, it: &it); |
130 | while ((p = css_task_iter_next(it: &it))) |
131 | update_classid_task(p, classid: cs->classid); |
132 | css_task_iter_end(it: &it); |
133 | |
134 | return 0; |
135 | } |
136 | |
137 | static struct cftype ss_files[] = { |
138 | { |
139 | .name = "classid" , |
140 | .read_u64 = read_classid, |
141 | .write_u64 = write_classid, |
142 | }, |
143 | { } /* terminate */ |
144 | }; |
145 | |
146 | struct cgroup_subsys net_cls_cgrp_subsys = { |
147 | .css_alloc = cgrp_css_alloc, |
148 | .css_online = cgrp_css_online, |
149 | .css_free = cgrp_css_free, |
150 | .attach = cgrp_attach, |
151 | .legacy_cftypes = ss_files, |
152 | }; |
153 | |