Merge tag 'ovl-fixes-5.2-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/mszere...
[linux-2.6-microblaze.git] / block / ioprio.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * fs/ioprio.c
4  *
5  * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
6  *
7  * Helper functions for setting/querying io priorities of processes. The
8  * system calls closely mimmick getpriority/setpriority, see the man page for
9  * those. The prio argument is a composite of prio class and prio data, where
10  * the data argument has meaning within that class. The standard scheduling
11  * classes have 8 distinct prio levels, with 0 being the highest prio and 7
12  * being the lowest.
13  *
14  * IOW, setting BE scheduling class with prio 2 is done ala:
15  *
16  * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
17  *
18  * ioprio_set(PRIO_PROCESS, pid, prio);
19  *
20  * See also Documentation/block/ioprio.txt
21  *
22  */
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
36 int 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 }
63 EXPORT_SYMBOL_GPL(set_task_ioprio);
64
65 int 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_ADMIN))
73                                 return -EPERM;
74                         /* fall through */
75                         /* rt has prio field too */
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
94 SYSCALL_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                         do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
123                                 ret = set_task_ioprio(p, ioprio);
124                                 if (ret)
125                                         break;
126                         } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
127                         break;
128                 case IOPRIO_WHO_USER:
129                         uid = make_kuid(current_user_ns(), who);
130                         if (!uid_valid(uid))
131                                 break;
132                         if (!who)
133                                 user = current_user();
134                         else
135                                 user = find_user(uid);
136
137                         if (!user)
138                                 break;
139
140                         for_each_process_thread(g, p) {
141                                 if (!uid_eq(task_uid(p), uid) ||
142                                     !task_pid_vnr(p))
143                                         continue;
144                                 ret = set_task_ioprio(p, ioprio);
145                                 if (ret)
146                                         goto free_uid;
147                         }
148 free_uid:
149                         if (who)
150                                 free_uid(user);
151                         break;
152                 default:
153                         ret = -EINVAL;
154         }
155
156         rcu_read_unlock();
157         return ret;
158 }
159
160 static int get_task_ioprio(struct task_struct *p)
161 {
162         int ret;
163
164         ret = security_task_getioprio(p);
165         if (ret)
166                 goto out;
167         ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
168         task_lock(p);
169         if (p->io_context)
170                 ret = p->io_context->ioprio;
171         task_unlock(p);
172 out:
173         return ret;
174 }
175
176 int ioprio_best(unsigned short aprio, unsigned short bprio)
177 {
178         if (!ioprio_valid(aprio))
179                 aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
180         if (!ioprio_valid(bprio))
181                 bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
182
183         return min(aprio, bprio);
184 }
185
186 SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
187 {
188         struct task_struct *g, *p;
189         struct user_struct *user;
190         struct pid *pgrp;
191         kuid_t uid;
192         int ret = -ESRCH;
193         int tmpio;
194
195         rcu_read_lock();
196         switch (which) {
197                 case IOPRIO_WHO_PROCESS:
198                         if (!who)
199                                 p = current;
200                         else
201                                 p = find_task_by_vpid(who);
202                         if (p)
203                                 ret = get_task_ioprio(p);
204                         break;
205                 case IOPRIO_WHO_PGRP:
206                         if (!who)
207                                 pgrp = task_pgrp(current);
208                         else
209                                 pgrp = find_vpid(who);
210                         do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
211                                 tmpio = get_task_ioprio(p);
212                                 if (tmpio < 0)
213                                         continue;
214                                 if (ret == -ESRCH)
215                                         ret = tmpio;
216                                 else
217                                         ret = ioprio_best(ret, tmpio);
218                         } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
219                         break;
220                 case IOPRIO_WHO_USER:
221                         uid = make_kuid(current_user_ns(), who);
222                         if (!who)
223                                 user = current_user();
224                         else
225                                 user = find_user(uid);
226
227                         if (!user)
228                                 break;
229
230                         for_each_process_thread(g, p) {
231                                 if (!uid_eq(task_uid(p), user->uid) ||
232                                     !task_pid_vnr(p))
233                                         continue;
234                                 tmpio = get_task_ioprio(p);
235                                 if (tmpio < 0)
236                                         continue;
237                                 if (ret == -ESRCH)
238                                         ret = tmpio;
239                                 else
240                                         ret = ioprio_best(ret, tmpio);
241                         }
242
243                         if (who)
244                                 free_uid(user);
245                         break;
246                 default:
247                         ret = -EINVAL;
248         }
249
250         rcu_read_unlock();
251         return ret;
252 }