1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
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
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 if (p->io_context)
149 ret = p->io_context->ioprio;
150out:
151 return ret;
152}
153
154int ioprio_best(unsigned short aprio, unsigned short bprio)
155{
156 unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
157 unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
158
159 if (aclass == IOPRIO_CLASS_NONE)
160 aclass = IOPRIO_CLASS_BE;
161 if (bclass == IOPRIO_CLASS_NONE)
162 bclass = IOPRIO_CLASS_BE;
163
164 if (aclass == bclass)
165 return min(aprio, bprio);
166 if (aclass > bclass)
167 return bprio;
168 else
169 return aprio;
170}
171
172SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
173{
174 struct task_struct *g, *p;
175 struct user_struct *user;
176 struct pid *pgrp;
177 int ret = -ESRCH;
178 int tmpio;
179
180 rcu_read_lock();
181 switch (which) {
182 case IOPRIO_WHO_PROCESS:
183 if (!who)
184 p = current;
185 else
186 p = find_task_by_vpid(who);
187 if (p)
188 ret = get_task_ioprio(p);
189 break;
190 case IOPRIO_WHO_PGRP:
191 if (!who)
192 pgrp = task_pgrp(current);
193 else
194 pgrp = find_vpid(who);
195 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
196 tmpio = get_task_ioprio(p);
197 if (tmpio < 0)
198 continue;
199 if (ret == -ESRCH)
200 ret = tmpio;
201 else
202 ret = ioprio_best(ret, tmpio);
203 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
204 break;
205 case IOPRIO_WHO_USER:
206 if (!who)
207 user = current_user();
208 else
209 user = find_user(who);
210
211 if (!user)
212 break;
213
214 do_each_thread(g, p) {
215 if (__task_cred(p)->uid != user->uid)
216 continue;
217 tmpio = get_task_ioprio(p);
218 if (tmpio < 0)
219 continue;
220 if (ret == -ESRCH)
221 ret = tmpio;
222 else
223 ret = ioprio_best(ret, tmpio);
224 } while_each_thread(g, p);
225
226 if (who)
227 free_uid(user);
228 break;
229 default:
230 ret = -EINVAL;
231 }
232
233 rcu_read_unlock();
234 return ret;
235}
236
