1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * net/core/netprio_cgroup.c Priority Control Group |
4 | * |
5 | * Authors: Neil Horman <nhorman@tuxdriver.com> |
6 | */ |
7 | |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | |
10 | #include <linux/module.h> |
11 | #include <linux/slab.h> |
12 | #include <linux/types.h> |
13 | #include <linux/string.h> |
14 | #include <linux/errno.h> |
15 | #include <linux/skbuff.h> |
16 | #include <linux/cgroup.h> |
17 | #include <linux/rcupdate.h> |
18 | #include <linux/atomic.h> |
19 | #include <linux/sched/task.h> |
20 | |
21 | #include <net/rtnetlink.h> |
22 | #include <net/pkt_cls.h> |
23 | #include <net/sock.h> |
24 | #include <net/netprio_cgroup.h> |
25 | |
26 | #include <linux/fdtable.h> |
27 | |
28 | /* |
29 | * netprio allocates per-net_device priomap array which is indexed by |
30 | * css->id. Limiting css ID to 16bits doesn't lose anything. |
31 | */ |
32 | #define NETPRIO_ID_MAX USHRT_MAX |
33 | |
34 | #define PRIOMAP_MIN_SZ 128 |
35 | |
36 | /* |
37 | * Extend @dev->priomap so that it's large enough to accommodate |
38 | * @target_idx. @dev->priomap.priomap_len > @target_idx after successful |
39 | * return. Must be called under rtnl lock. |
40 | */ |
41 | static int extend_netdev_table(struct net_device *dev, u32 target_idx) |
42 | { |
43 | struct netprio_map *old, *new; |
44 | size_t new_sz, new_len; |
45 | |
46 | /* is the existing priomap large enough? */ |
47 | old = rtnl_dereference(dev->priomap); |
48 | if (old && old->priomap_len > target_idx) |
49 | return 0; |
50 | |
51 | /* |
52 | * Determine the new size. Let's keep it power-of-two. We start |
53 | * from PRIOMAP_MIN_SZ and double it until it's large enough to |
54 | * accommodate @target_idx. |
55 | */ |
56 | new_sz = PRIOMAP_MIN_SZ; |
57 | while (true) { |
58 | new_len = (new_sz - offsetof(struct netprio_map, priomap)) / |
59 | sizeof(new->priomap[0]); |
60 | if (new_len > target_idx) |
61 | break; |
62 | new_sz *= 2; |
63 | /* overflowed? */ |
64 | if (WARN_ON(new_sz < PRIOMAP_MIN_SZ)) |
65 | return -ENOSPC; |
66 | } |
67 | |
68 | /* allocate & copy */ |
69 | new = kzalloc(size: new_sz, GFP_KERNEL); |
70 | if (!new) |
71 | return -ENOMEM; |
72 | |
73 | if (old) |
74 | memcpy(new->priomap, old->priomap, |
75 | old->priomap_len * sizeof(old->priomap[0])); |
76 | |
77 | new->priomap_len = new_len; |
78 | |
79 | /* install the new priomap */ |
80 | rcu_assign_pointer(dev->priomap, new); |
81 | if (old) |
82 | kfree_rcu(old, rcu); |
83 | return 0; |
84 | } |
85 | |
86 | /** |
87 | * netprio_prio - return the effective netprio of a cgroup-net_device pair |
88 | * @css: css part of the target pair |
89 | * @dev: net_device part of the target pair |
90 | * |
91 | * Should be called under RCU read or rtnl lock. |
92 | */ |
93 | static u32 netprio_prio(struct cgroup_subsys_state *css, struct net_device *dev) |
94 | { |
95 | struct netprio_map *map = rcu_dereference_rtnl(dev->priomap); |
96 | int id = css->id; |
97 | |
98 | if (map && id < map->priomap_len) |
99 | return map->priomap[id]; |
100 | return 0; |
101 | } |
102 | |
103 | /** |
104 | * netprio_set_prio - set netprio on a cgroup-net_device pair |
105 | * @css: css part of the target pair |
106 | * @dev: net_device part of the target pair |
107 | * @prio: prio to set |
108 | * |
109 | * Set netprio to @prio on @css-@dev pair. Should be called under rtnl |
110 | * lock and may fail under memory pressure for non-zero @prio. |
111 | */ |
112 | static int netprio_set_prio(struct cgroup_subsys_state *css, |
113 | struct net_device *dev, u32 prio) |
114 | { |
115 | struct netprio_map *map; |
116 | int id = css->id; |
117 | int ret; |
118 | |
119 | /* avoid extending priomap for zero writes */ |
120 | map = rtnl_dereference(dev->priomap); |
121 | if (!prio && (!map || map->priomap_len <= id)) |
122 | return 0; |
123 | |
124 | ret = extend_netdev_table(dev, target_idx: id); |
125 | if (ret) |
126 | return ret; |
127 | |
128 | map = rtnl_dereference(dev->priomap); |
129 | map->priomap[id] = prio; |
130 | return 0; |
131 | } |
132 | |
133 | static struct cgroup_subsys_state * |
134 | cgrp_css_alloc(struct cgroup_subsys_state *parent_css) |
135 | { |
136 | struct cgroup_subsys_state *css; |
137 | |
138 | css = kzalloc(size: sizeof(*css), GFP_KERNEL); |
139 | if (!css) |
140 | return ERR_PTR(error: -ENOMEM); |
141 | |
142 | return css; |
143 | } |
144 | |
145 | static int cgrp_css_online(struct cgroup_subsys_state *css) |
146 | { |
147 | struct cgroup_subsys_state *parent_css = css->parent; |
148 | struct net_device *dev; |
149 | int ret = 0; |
150 | |
151 | if (css->id > NETPRIO_ID_MAX) |
152 | return -ENOSPC; |
153 | |
154 | if (!parent_css) |
155 | return 0; |
156 | |
157 | rtnl_lock(); |
158 | /* |
159 | * Inherit prios from the parent. As all prios are set during |
160 | * onlining, there is no need to clear them on offline. |
161 | */ |
162 | for_each_netdev(&init_net, dev) { |
163 | u32 prio = netprio_prio(css: parent_css, dev); |
164 | |
165 | ret = netprio_set_prio(css, dev, prio); |
166 | if (ret) |
167 | break; |
168 | } |
169 | rtnl_unlock(); |
170 | return ret; |
171 | } |
172 | |
173 | static void cgrp_css_free(struct cgroup_subsys_state *css) |
174 | { |
175 | kfree(objp: css); |
176 | } |
177 | |
178 | static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft) |
179 | { |
180 | return css->id; |
181 | } |
182 | |
183 | static int read_priomap(struct seq_file *sf, void *v) |
184 | { |
185 | struct net_device *dev; |
186 | |
187 | rcu_read_lock(); |
188 | for_each_netdev_rcu(&init_net, dev) |
189 | seq_printf(m: sf, fmt: "%s %u\n" , dev->name, |
190 | netprio_prio(css: seq_css(seq: sf), dev)); |
191 | rcu_read_unlock(); |
192 | return 0; |
193 | } |
194 | |
195 | static ssize_t write_priomap(struct kernfs_open_file *of, |
196 | char *buf, size_t nbytes, loff_t off) |
197 | { |
198 | char devname[IFNAMSIZ + 1]; |
199 | struct net_device *dev; |
200 | u32 prio; |
201 | int ret; |
202 | |
203 | if (sscanf(buf, "%" __stringify(IFNAMSIZ)"s %u" , devname, &prio) != 2) |
204 | return -EINVAL; |
205 | |
206 | dev = dev_get_by_name(net: &init_net, name: devname); |
207 | if (!dev) |
208 | return -ENODEV; |
209 | |
210 | rtnl_lock(); |
211 | |
212 | ret = netprio_set_prio(css: of_css(of), dev, prio); |
213 | |
214 | rtnl_unlock(); |
215 | dev_put(dev); |
216 | return ret ?: nbytes; |
217 | } |
218 | |
219 | static int update_netprio(const void *v, struct file *file, unsigned n) |
220 | { |
221 | struct socket *sock = sock_from_file(file); |
222 | |
223 | if (sock) |
224 | sock_cgroup_set_prioidx(skcd: &sock->sk->sk_cgrp_data, |
225 | prioidx: (unsigned long)v); |
226 | return 0; |
227 | } |
228 | |
229 | static void net_prio_attach(struct cgroup_taskset *tset) |
230 | { |
231 | struct task_struct *p; |
232 | struct cgroup_subsys_state *css; |
233 | |
234 | cgroup_taskset_for_each(p, css, tset) { |
235 | void *v = (void *)(unsigned long)css->id; |
236 | |
237 | task_lock(p); |
238 | iterate_fd(p->files, 0, update_netprio, v); |
239 | task_unlock(p); |
240 | } |
241 | } |
242 | |
243 | static struct cftype ss_files[] = { |
244 | { |
245 | .name = "prioidx" , |
246 | .read_u64 = read_prioidx, |
247 | }, |
248 | { |
249 | .name = "ifpriomap" , |
250 | .seq_show = read_priomap, |
251 | .write = write_priomap, |
252 | }, |
253 | { } /* terminate */ |
254 | }; |
255 | |
256 | struct cgroup_subsys net_prio_cgrp_subsys = { |
257 | .css_alloc = cgrp_css_alloc, |
258 | .css_online = cgrp_css_online, |
259 | .css_free = cgrp_css_free, |
260 | .attach = net_prio_attach, |
261 | .legacy_cftypes = ss_files, |
262 | }; |
263 | |
264 | static int netprio_device_event(struct notifier_block *unused, |
265 | unsigned long event, void *ptr) |
266 | { |
267 | struct net_device *dev = netdev_notifier_info_to_dev(info: ptr); |
268 | struct netprio_map *old; |
269 | |
270 | /* |
271 | * Note this is called with rtnl_lock held so we have update side |
272 | * protection on our rcu assignments |
273 | */ |
274 | |
275 | switch (event) { |
276 | case NETDEV_UNREGISTER: |
277 | old = rtnl_dereference(dev->priomap); |
278 | RCU_INIT_POINTER(dev->priomap, NULL); |
279 | if (old) |
280 | kfree_rcu(old, rcu); |
281 | break; |
282 | } |
283 | return NOTIFY_DONE; |
284 | } |
285 | |
286 | static struct notifier_block netprio_device_notifier = { |
287 | .notifier_call = netprio_device_event |
288 | }; |
289 | |
290 | static int __init init_cgroup_netprio(void) |
291 | { |
292 | register_netdevice_notifier(nb: &netprio_device_notifier); |
293 | return 0; |
294 | } |
295 | subsys_initcall(init_cgroup_netprio); |
296 | |