blob: 07fac8b0f287b5abd23cceb683f0f3a6bfb4013c [file] [log] [blame]
lh9ed821d2023-04-07 01:36:19 -07001/*
2 * fs/ioprio.c
3 *
4 * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
5 *
6 * Helper functions for setting/querying io priorities of processes. The
7 * system calls closely mimmick getpriority/setpriority, see the man page for
8 * those. The prio argument is a composite of prio class and prio data, where
9 * the data argument has meaning within that class. The standard scheduling
10 * classes have 8 distinct prio levels, with 0 being the highest prio and 7
11 * being the lowest.
12 *
13 * IOW, setting BE scheduling class with prio 2 is done ala:
14 *
15 * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
16 *
17 * ioprio_set(PRIO_PROCESS, pid, prio);
18 *
19 * See also Documentation/block/ioprio.txt
20 *
21 */
22#include <linux/gfp.h>
23#include <linux/kernel.h>
24#include <linux/export.h>
25#include <linux/ioprio.h>
26#include <linux/blkdev.h>
27#include <linux/capability.h>
28#include <linux/syscalls.h>
29#include <linux/security.h>
30#include <linux/pid_namespace.h>
31
32int set_task_ioprio(struct task_struct *task, int ioprio)
33{
34 int err;
35 struct io_context *ioc;
36 const struct cred *cred = current_cred(), *tcred;
37
38 rcu_read_lock();
39 tcred = __task_cred(task);
40 if (tcred->uid != cred->euid &&
41 tcred->uid != cred->uid && !capable(CAP_SYS_NICE)) {
42 rcu_read_unlock();
43 return -EPERM;
44 }
45 rcu_read_unlock();
46
47 err = security_task_setioprio(task, ioprio);
48 if (err)
49 return err;
50
51 ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
52 if (ioc) {
53 ioc_ioprio_changed(ioc, ioprio);
54 put_io_context(ioc);
55 }
56
57 return err;
58}
59EXPORT_SYMBOL_GPL(set_task_ioprio);
60
61SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
62{
63 int class = IOPRIO_PRIO_CLASS(ioprio);
64 int data = IOPRIO_PRIO_DATA(ioprio);
65 struct task_struct *p, *g;
66 struct user_struct *user;
67 struct pid *pgrp;
68 int ret;
69
70 switch (class) {
71 case IOPRIO_CLASS_RT:
72 if (!capable(CAP_SYS_ADMIN))
73 return -EPERM;
74 /* fall through, rt has prio field too */
75 case IOPRIO_CLASS_BE:
76 if (data >= IOPRIO_BE_NR || data < 0)
77 return -EINVAL;
78
79 break;
80 case IOPRIO_CLASS_IDLE:
81 break;
82 case IOPRIO_CLASS_NONE:
83 if (data)
84 return -EINVAL;
85 break;
86 default:
87 return -EINVAL;
88 }
89
90 ret = -ESRCH;
91 rcu_read_lock();
92 switch (which) {
93 case IOPRIO_WHO_PROCESS:
94 if (!who)
95 p = current;
96 else
97 p = find_task_by_vpid(who);
98 if (p)
99 ret = set_task_ioprio(p, ioprio);
100 break;
101 case IOPRIO_WHO_PGRP:
102 if (!who)
103 pgrp = task_pgrp(current);
104 else
105 pgrp = find_vpid(who);
106 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
107 ret = set_task_ioprio(p, ioprio);
108 if (ret)
109 break;
110 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
111 break;
112 case IOPRIO_WHO_USER:
113 if (!who)
114 user = current_user();
115 else
116 user = find_user(who);
117
118 if (!user)
119 break;
120
121 do_each_thread(g, p) {
122 if (__task_cred(p)->uid != who)
123 continue;
124 ret = set_task_ioprio(p, ioprio);
125 if (ret)
126 goto free_uid;
127 } while_each_thread(g, p);
128free_uid:
129 if (who)
130 free_uid(user);
131 break;
132 default:
133 ret = -EINVAL;
134 }
135
136 rcu_read_unlock();
137 return ret;
138}
139
140static int get_task_ioprio(struct task_struct *p)
141{
142 int ret;
143
144 ret = security_task_getioprio(p);
145 if (ret)
146 goto out;
147 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
148 /*modify for HUB CVE-2016-7911*/
149 task_lock(p);
150 if (p->io_context)
151 ret = p->io_context->ioprio;
152 task_unlock(p);
153out:
154 return ret;
155}
156
157int ioprio_best(unsigned short aprio, unsigned short bprio)
158{
159 unsigned short aclass;
160 unsigned short bclass;
161
162 if (!ioprio_valid(aprio))
163 aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
164 if (!ioprio_valid(bprio))
165 bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
166
167 aclass = IOPRIO_PRIO_CLASS(aprio);
168 bclass = IOPRIO_PRIO_CLASS(bprio);
169 if (aclass == bclass)
170 return min(aprio, bprio);
171 if (aclass > bclass)
172 return bprio;
173 else
174 return aprio;
175}
176
177SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
178{
179 struct task_struct *g, *p;
180 struct user_struct *user;
181 struct pid *pgrp;
182 int ret = -ESRCH;
183 int tmpio;
184
185 rcu_read_lock();
186 switch (which) {
187 case IOPRIO_WHO_PROCESS:
188 if (!who)
189 p = current;
190 else
191 p = find_task_by_vpid(who);
192 if (p)
193 ret = get_task_ioprio(p);
194 break;
195 case IOPRIO_WHO_PGRP:
196 if (!who)
197 pgrp = task_pgrp(current);
198 else
199 pgrp = find_vpid(who);
200 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
201 tmpio = get_task_ioprio(p);
202 if (tmpio < 0)
203 continue;
204 if (ret == -ESRCH)
205 ret = tmpio;
206 else
207 ret = ioprio_best(ret, tmpio);
208 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
209 break;
210 case IOPRIO_WHO_USER:
211 if (!who)
212 user = current_user();
213 else
214 user = find_user(who);
215
216 if (!user)
217 break;
218
219 do_each_thread(g, p) {
220 if (__task_cred(p)->uid != user->uid)
221 continue;
222 tmpio = get_task_ioprio(p);
223 if (tmpio < 0)
224 continue;
225 if (ret == -ESRCH)
226 ret = tmpio;
227 else
228 ret = ioprio_best(ret, tmpio);
229 } while_each_thread(g, p);
230
231 if (who)
232 free_uid(user);
233 break;
234 default:
235 ret = -EINVAL;
236 }
237
238 rcu_read_unlock();
239 return ret;
240}