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3dcf60bc | 1 | // SPDX-License-Identifier: GPL-2.0 |
22e2c507 JA |
2 | /* |
3 | * fs/ioprio.c | |
4 | * | |
0fe23479 | 5 | * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk> |
22e2c507 JA |
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 | * | |
898bd37a | 20 | * See also Documentation/block/ioprio.rst |
22e2c507 JA |
21 | * |
22 | */ | |
5a0e3ad6 | 23 | #include <linux/gfp.h> |
22e2c507 | 24 | #include <linux/kernel.h> |
afeacc8c | 25 | #include <linux/export.h> |
22e2c507 | 26 | #include <linux/ioprio.h> |
5b825c3a | 27 | #include <linux/cred.h> |
22e2c507 | 28 | #include <linux/blkdev.h> |
16f7e0fe | 29 | #include <linux/capability.h> |
8703e8a4 | 30 | #include <linux/sched/user.h> |
f719ff9b | 31 | #include <linux/sched/task.h> |
9abdc4cd | 32 | #include <linux/syscalls.h> |
03e68060 | 33 | #include <linux/security.h> |
b488893a | 34 | #include <linux/pid_namespace.h> |
22e2c507 | 35 | |
b3881f74 | 36 | int set_task_ioprio(struct task_struct *task, int ioprio) |
22e2c507 | 37 | { |
03e68060 | 38 | int err; |
22e2c507 | 39 | struct io_context *ioc; |
c69e8d9c | 40 | const struct cred *cred = current_cred(), *tcred; |
22e2c507 | 41 | |
c69e8d9c DH |
42 | rcu_read_lock(); |
43 | tcred = __task_cred(task); | |
8e96e3b7 EB |
44 | if (!uid_eq(tcred->uid, cred->euid) && |
45 | !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) { | |
c69e8d9c | 46 | rcu_read_unlock(); |
22e2c507 | 47 | return -EPERM; |
c69e8d9c DH |
48 | } |
49 | rcu_read_unlock(); | |
22e2c507 | 50 | |
03e68060 JM |
51 | err = security_task_setioprio(task, ioprio); |
52 | if (err) | |
53 | return err; | |
54 | ||
6e736be7 TH |
55 | ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE); |
56 | if (ioc) { | |
2b566fa5 | 57 | ioc->ioprio = ioprio; |
11a3122f | 58 | put_io_context(ioc); |
fd0928df | 59 | } |
22e2c507 | 60 | |
fd0928df | 61 | return err; |
22e2c507 | 62 | } |
b3881f74 | 63 | EXPORT_SYMBOL_GPL(set_task_ioprio); |
22e2c507 | 64 | |
aa434577 | 65 | int ioprio_check_cap(int ioprio) |
22e2c507 JA |
66 | { |
67 | int class = IOPRIO_PRIO_CLASS(ioprio); | |
68 | int data = IOPRIO_PRIO_DATA(ioprio); | |
22e2c507 JA |
69 | |
70 | switch (class) { | |
71 | case IOPRIO_CLASS_RT: | |
9d3a39a5 | 72 | if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN)) |
22e2c507 | 73 | return -EPERM; |
df561f66 | 74 | fallthrough; |
e29387eb | 75 | /* rt has prio field too */ |
22e2c507 | 76 | case IOPRIO_CLASS_BE: |
202bc942 | 77 | if (data >= IOPRIO_NR_LEVELS || data < 0) |
22e2c507 | 78 | return -EINVAL; |
22e2c507 JA |
79 | break; |
80 | case IOPRIO_CLASS_IDLE: | |
81 | break; | |
8ec680e4 JA |
82 | case IOPRIO_CLASS_NONE: |
83 | if (data) | |
84 | return -EINVAL; | |
85 | break; | |
22e2c507 JA |
86 | default: |
87 | return -EINVAL; | |
88 | } | |
89 | ||
aa434577 AM |
90 | return 0; |
91 | } | |
92 | ||
93 | SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio) | |
94 | { | |
95 | struct task_struct *p, *g; | |
96 | struct user_struct *user; | |
97 | struct pid *pgrp; | |
98 | kuid_t uid; | |
99 | int ret; | |
100 | ||
101 | ret = ioprio_check_cap(ioprio); | |
102 | if (ret) | |
103 | return ret; | |
104 | ||
22e2c507 | 105 | ret = -ESRCH; |
d69b78ba | 106 | rcu_read_lock(); |
22e2c507 JA |
107 | switch (which) { |
108 | case IOPRIO_WHO_PROCESS: | |
109 | if (!who) | |
110 | p = current; | |
111 | else | |
228ebcbe | 112 | p = find_task_by_vpid(who); |
22e2c507 JA |
113 | if (p) |
114 | ret = set_task_ioprio(p, ioprio); | |
115 | break; | |
116 | case IOPRIO_WHO_PGRP: | |
117 | if (!who) | |
41487c65 EB |
118 | pgrp = task_pgrp(current); |
119 | else | |
b488893a | 120 | pgrp = find_vpid(who); |
40c7fd3f PZ |
121 | |
122 | read_lock(&tasklist_lock); | |
2d70b68d | 123 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { |
22e2c507 | 124 | ret = set_task_ioprio(p, ioprio); |
40c7fd3f PZ |
125 | if (ret) { |
126 | read_unlock(&tasklist_lock); | |
127 | goto out; | |
128 | } | |
2d70b68d | 129 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); |
40c7fd3f PZ |
130 | read_unlock(&tasklist_lock); |
131 | ||
22e2c507 JA |
132 | break; |
133 | case IOPRIO_WHO_USER: | |
7b44ab97 EB |
134 | uid = make_kuid(current_user_ns(), who); |
135 | if (!uid_valid(uid)) | |
136 | break; | |
22e2c507 | 137 | if (!who) |
86a264ab | 138 | user = current_user(); |
22e2c507 | 139 | else |
7b44ab97 | 140 | user = find_user(uid); |
22e2c507 JA |
141 | |
142 | if (!user) | |
143 | break; | |
144 | ||
612dafab | 145 | for_each_process_thread(g, p) { |
8639b461 BS |
146 | if (!uid_eq(task_uid(p), uid) || |
147 | !task_pid_vnr(p)) | |
22e2c507 JA |
148 | continue; |
149 | ret = set_task_ioprio(p, ioprio); | |
150 | if (ret) | |
78bd4d48 | 151 | goto free_uid; |
612dafab | 152 | } |
78bd4d48 | 153 | free_uid: |
22e2c507 JA |
154 | if (who) |
155 | free_uid(user); | |
156 | break; | |
157 | default: | |
158 | ret = -EINVAL; | |
159 | } | |
160 | ||
40c7fd3f | 161 | out: |
d69b78ba | 162 | rcu_read_unlock(); |
22e2c507 JA |
163 | return ret; |
164 | } | |
165 | ||
a1836a42 DQ |
166 | static int get_task_ioprio(struct task_struct *p) |
167 | { | |
168 | int ret; | |
169 | ||
170 | ret = security_task_getioprio(p); | |
171 | if (ret) | |
172 | goto out; | |
e70344c0 | 173 | ret = IOPRIO_DEFAULT; |
8ba86821 | 174 | task_lock(p); |
fd0928df JA |
175 | if (p->io_context) |
176 | ret = p->io_context->ioprio; | |
8ba86821 | 177 | task_unlock(p); |
a1836a42 DQ |
178 | out: |
179 | return ret; | |
180 | } | |
181 | ||
e014ff8d ON |
182 | int ioprio_best(unsigned short aprio, unsigned short bprio) |
183 | { | |
ece9c72a | 184 | if (!ioprio_valid(aprio)) |
e70344c0 | 185 | aprio = IOPRIO_DEFAULT; |
ece9c72a | 186 | if (!ioprio_valid(bprio)) |
e70344c0 | 187 | bprio = IOPRIO_DEFAULT; |
e014ff8d | 188 | |
9a87182c | 189 | return min(aprio, bprio); |
e014ff8d ON |
190 | } |
191 | ||
938bb9f5 | 192 | SYSCALL_DEFINE2(ioprio_get, int, which, int, who) |
22e2c507 JA |
193 | { |
194 | struct task_struct *g, *p; | |
195 | struct user_struct *user; | |
41487c65 | 196 | struct pid *pgrp; |
7b44ab97 | 197 | kuid_t uid; |
22e2c507 | 198 | int ret = -ESRCH; |
a1836a42 | 199 | int tmpio; |
22e2c507 | 200 | |
d69b78ba | 201 | rcu_read_lock(); |
22e2c507 JA |
202 | switch (which) { |
203 | case IOPRIO_WHO_PROCESS: | |
204 | if (!who) | |
205 | p = current; | |
206 | else | |
228ebcbe | 207 | p = find_task_by_vpid(who); |
22e2c507 | 208 | if (p) |
a1836a42 | 209 | ret = get_task_ioprio(p); |
22e2c507 JA |
210 | break; |
211 | case IOPRIO_WHO_PGRP: | |
212 | if (!who) | |
41487c65 EB |
213 | pgrp = task_pgrp(current); |
214 | else | |
b488893a | 215 | pgrp = find_vpid(who); |
2d70b68d | 216 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { |
a1836a42 DQ |
217 | tmpio = get_task_ioprio(p); |
218 | if (tmpio < 0) | |
219 | continue; | |
22e2c507 | 220 | if (ret == -ESRCH) |
a1836a42 | 221 | ret = tmpio; |
22e2c507 | 222 | else |
a1836a42 | 223 | ret = ioprio_best(ret, tmpio); |
2d70b68d | 224 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); |
22e2c507 JA |
225 | break; |
226 | case IOPRIO_WHO_USER: | |
7b44ab97 | 227 | uid = make_kuid(current_user_ns(), who); |
22e2c507 | 228 | if (!who) |
86a264ab | 229 | user = current_user(); |
22e2c507 | 230 | else |
7b44ab97 | 231 | user = find_user(uid); |
22e2c507 JA |
232 | |
233 | if (!user) | |
234 | break; | |
235 | ||
612dafab | 236 | for_each_process_thread(g, p) { |
8639b461 BS |
237 | if (!uid_eq(task_uid(p), user->uid) || |
238 | !task_pid_vnr(p)) | |
22e2c507 | 239 | continue; |
a1836a42 DQ |
240 | tmpio = get_task_ioprio(p); |
241 | if (tmpio < 0) | |
242 | continue; | |
22e2c507 | 243 | if (ret == -ESRCH) |
a1836a42 | 244 | ret = tmpio; |
22e2c507 | 245 | else |
a1836a42 | 246 | ret = ioprio_best(ret, tmpio); |
612dafab | 247 | } |
22e2c507 JA |
248 | |
249 | if (who) | |
250 | free_uid(user); | |
251 | break; | |
252 | default: | |
253 | ret = -EINVAL; | |
254 | } | |
255 | ||
d69b78ba | 256 | rcu_read_unlock(); |
22e2c507 JA |
257 | return ret; |
258 | } |