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23#include <linux/gfp.h>
24#include <linux/kernel.h>
25#include <linux/export.h>
26#include <linux/ioprio.h>
27#include <linux/cred.h>
28#include <linux/blkdev.h>
29#include <linux/capability.h>
30#include <linux/sched/user.h>
31#include <linux/sched/task.h>
32#include <linux/syscalls.h>
33#include <linux/security.h>
34#include <linux/pid_namespace.h>
35
36int set_task_ioprio(struct task_struct *task, int ioprio)
37{
38 int err;
39 struct io_context *ioc;
40 const struct cred *cred = current_cred(), *tcred;
41
42 rcu_read_lock();
43 tcred = __task_cred(task);
44 if (!uid_eq(tcred->uid, cred->euid) &&
45 !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) {
46 rcu_read_unlock();
47 return -EPERM;
48 }
49 rcu_read_unlock();
50
51 err = security_task_setioprio(task, ioprio);
52 if (err)
53 return err;
54
55 ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
56 if (ioc) {
57 ioc->ioprio = ioprio;
58 put_io_context(ioc);
59 }
60
61 return err;
62}
63EXPORT_SYMBOL_GPL(set_task_ioprio);
64
65int ioprio_check_cap(int ioprio)
66{
67 int class = IOPRIO_PRIO_CLASS(ioprio);
68 int data = IOPRIO_PRIO_DATA(ioprio);
69
70 switch (class) {
71 case IOPRIO_CLASS_RT:
72 if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN))
73 return -EPERM;
74 fallthrough;
75
76 case IOPRIO_CLASS_BE:
77 if (data >= IOPRIO_BE_NR || data < 0)
78 return -EINVAL;
79
80 break;
81 case IOPRIO_CLASS_IDLE:
82 break;
83 case IOPRIO_CLASS_NONE:
84 if (data)
85 return -EINVAL;
86 break;
87 default:
88 return -EINVAL;
89 }
90
91 return 0;
92}
93
94SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
95{
96 struct task_struct *p, *g;
97 struct user_struct *user;
98 struct pid *pgrp;
99 kuid_t uid;
100 int ret;
101
102 ret = ioprio_check_cap(ioprio);
103 if (ret)
104 return ret;
105
106 ret = -ESRCH;
107 rcu_read_lock();
108 switch (which) {
109 case IOPRIO_WHO_PROCESS:
110 if (!who)
111 p = current;
112 else
113 p = find_task_by_vpid(who);
114 if (p)
115 ret = set_task_ioprio(p, ioprio);
116 break;
117 case IOPRIO_WHO_PGRP:
118 if (!who)
119 pgrp = task_pgrp(current);
120 else
121 pgrp = find_vpid(who);
122
123 read_lock(&tasklist_lock);
124 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
125 ret = set_task_ioprio(p, ioprio);
126 if (ret) {
127 read_unlock(&tasklist_lock);
128 goto out;
129 }
130 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
131 read_unlock(&tasklist_lock);
132
133 break;
134 case IOPRIO_WHO_USER:
135 uid = make_kuid(current_user_ns(), who);
136 if (!uid_valid(uid))
137 break;
138 if (!who)
139 user = current_user();
140 else
141 user = find_user(uid);
142
143 if (!user)
144 break;
145
146 for_each_process_thread(g, p) {
147 if (!uid_eq(task_uid(p), uid) ||
148 !task_pid_vnr(p))
149 continue;
150 ret = set_task_ioprio(p, ioprio);
151 if (ret)
152 goto free_uid;
153 }
154free_uid:
155 if (who)
156 free_uid(user);
157 break;
158 default:
159 ret = -EINVAL;
160 }
161
162out:
163 rcu_read_unlock();
164 return ret;
165}
166
167static int get_task_ioprio(struct task_struct *p)
168{
169 int ret;
170
171 ret = security_task_getioprio(p);
172 if (ret)
173 goto out;
174 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
175 task_lock(p);
176 if (p->io_context)
177 ret = p->io_context->ioprio;
178 task_unlock(p);
179out:
180 return ret;
181}
182
183int ioprio_best(unsigned short aprio, unsigned short bprio)
184{
185 if (!ioprio_valid(aprio))
186 aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
187 if (!ioprio_valid(bprio))
188 bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
189
190 return min(aprio, bprio);
191}
192
193SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
194{
195 struct task_struct *g, *p;
196 struct user_struct *user;
197 struct pid *pgrp;
198 kuid_t uid;
199 int ret = -ESRCH;
200 int tmpio;
201
202 rcu_read_lock();
203 switch (which) {
204 case IOPRIO_WHO_PROCESS:
205 if (!who)
206 p = current;
207 else
208 p = find_task_by_vpid(who);
209 if (p)
210 ret = get_task_ioprio(p);
211 break;
212 case IOPRIO_WHO_PGRP:
213 if (!who)
214 pgrp = task_pgrp(current);
215 else
216 pgrp = find_vpid(who);
217 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
218 tmpio = get_task_ioprio(p);
219 if (tmpio < 0)
220 continue;
221 if (ret == -ESRCH)
222 ret = tmpio;
223 else
224 ret = ioprio_best(ret, tmpio);
225 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
226 break;
227 case IOPRIO_WHO_USER:
228 uid = make_kuid(current_user_ns(), who);
229 if (!who)
230 user = current_user();
231 else
232 user = find_user(uid);
233
234 if (!user)
235 break;
236
237 for_each_process_thread(g, p) {
238 if (!uid_eq(task_uid(p), user->uid) ||
239 !task_pid_vnr(p))
240 continue;
241 tmpio = get_task_ioprio(p);
242 if (tmpio < 0)
243 continue;
244 if (ret == -ESRCH)
245 ret = tmpio;
246 else
247 ret = ioprio_best(ret, tmpio);
248 }
249
250 if (who)
251 free_uid(user);
252 break;
253 default:
254 ret = -EINVAL;
255 }
256
257 rcu_read_unlock();
258 return ret;
259}
260
