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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 JA |
24 | #include <linux/kernel.h> |
25 | #include <linux/ioprio.h> | |
5b825c3a | 26 | #include <linux/cred.h> |
22e2c507 | 27 | #include <linux/blkdev.h> |
16f7e0fe | 28 | #include <linux/capability.h> |
9abdc4cd | 29 | #include <linux/syscalls.h> |
03e68060 | 30 | #include <linux/security.h> |
b488893a | 31 | #include <linux/pid_namespace.h> |
22e2c507 | 32 | |
aa434577 | 33 | int ioprio_check_cap(int ioprio) |
22e2c507 JA |
34 | { |
35 | int class = IOPRIO_PRIO_CLASS(ioprio); | |
36 | int data = IOPRIO_PRIO_DATA(ioprio); | |
22e2c507 JA |
37 | |
38 | switch (class) { | |
39 | case IOPRIO_CLASS_RT: | |
94c4b4fd AD |
40 | /* |
41 | * Originally this only checked for CAP_SYS_ADMIN, | |
42 | * which was implicitly allowed for pid 0 by security | |
43 | * modules such as SELinux. Make sure we check | |
44 | * CAP_SYS_ADMIN first to avoid a denial/avc for | |
45 | * possibly missing CAP_SYS_NICE permission. | |
46 | */ | |
47 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE)) | |
22e2c507 | 48 | return -EPERM; |
df561f66 | 49 | fallthrough; |
e29387eb | 50 | /* rt has prio field too */ |
22e2c507 | 51 | case IOPRIO_CLASS_BE: |
202bc942 | 52 | if (data >= IOPRIO_NR_LEVELS || data < 0) |
22e2c507 | 53 | return -EINVAL; |
22e2c507 JA |
54 | break; |
55 | case IOPRIO_CLASS_IDLE: | |
56 | break; | |
8ec680e4 JA |
57 | case IOPRIO_CLASS_NONE: |
58 | if (data) | |
59 | return -EINVAL; | |
60 | break; | |
22e2c507 JA |
61 | default: |
62 | return -EINVAL; | |
63 | } | |
64 | ||
aa434577 AM |
65 | return 0; |
66 | } | |
67 | ||
68 | SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio) | |
69 | { | |
70 | struct task_struct *p, *g; | |
71 | struct user_struct *user; | |
72 | struct pid *pgrp; | |
73 | kuid_t uid; | |
74 | int ret; | |
75 | ||
76 | ret = ioprio_check_cap(ioprio); | |
77 | if (ret) | |
78 | return ret; | |
79 | ||
22e2c507 | 80 | ret = -ESRCH; |
d69b78ba | 81 | rcu_read_lock(); |
22e2c507 JA |
82 | switch (which) { |
83 | case IOPRIO_WHO_PROCESS: | |
84 | if (!who) | |
85 | p = current; | |
86 | else | |
228ebcbe | 87 | p = find_task_by_vpid(who); |
22e2c507 JA |
88 | if (p) |
89 | ret = set_task_ioprio(p, ioprio); | |
90 | break; | |
91 | case IOPRIO_WHO_PGRP: | |
92 | if (!who) | |
41487c65 EB |
93 | pgrp = task_pgrp(current); |
94 | else | |
b488893a | 95 | pgrp = find_vpid(who); |
40c7fd3f PZ |
96 | |
97 | read_lock(&tasklist_lock); | |
2d70b68d | 98 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { |
22e2c507 | 99 | ret = set_task_ioprio(p, ioprio); |
40c7fd3f PZ |
100 | if (ret) { |
101 | read_unlock(&tasklist_lock); | |
102 | goto out; | |
103 | } | |
2d70b68d | 104 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); |
40c7fd3f PZ |
105 | read_unlock(&tasklist_lock); |
106 | ||
22e2c507 JA |
107 | break; |
108 | case IOPRIO_WHO_USER: | |
7b44ab97 EB |
109 | uid = make_kuid(current_user_ns(), who); |
110 | if (!uid_valid(uid)) | |
111 | break; | |
22e2c507 | 112 | if (!who) |
86a264ab | 113 | user = current_user(); |
22e2c507 | 114 | else |
7b44ab97 | 115 | user = find_user(uid); |
22e2c507 JA |
116 | |
117 | if (!user) | |
118 | break; | |
119 | ||
612dafab | 120 | for_each_process_thread(g, p) { |
8639b461 BS |
121 | if (!uid_eq(task_uid(p), uid) || |
122 | !task_pid_vnr(p)) | |
22e2c507 JA |
123 | continue; |
124 | ret = set_task_ioprio(p, ioprio); | |
125 | if (ret) | |
78bd4d48 | 126 | goto free_uid; |
612dafab | 127 | } |
78bd4d48 | 128 | free_uid: |
22e2c507 JA |
129 | if (who) |
130 | free_uid(user); | |
131 | break; | |
132 | default: | |
133 | ret = -EINVAL; | |
134 | } | |
135 | ||
40c7fd3f | 136 | out: |
d69b78ba | 137 | rcu_read_unlock(); |
22e2c507 JA |
138 | return ret; |
139 | } | |
140 | ||
a1836a42 DQ |
141 | static int get_task_ioprio(struct task_struct *p) |
142 | { | |
143 | int ret; | |
144 | ||
145 | ret = security_task_getioprio(p); | |
146 | if (ret) | |
147 | goto out; | |
e70344c0 | 148 | ret = IOPRIO_DEFAULT; |
8ba86821 | 149 | task_lock(p); |
fd0928df JA |
150 | if (p->io_context) |
151 | ret = p->io_context->ioprio; | |
8ba86821 | 152 | task_unlock(p); |
a1836a42 DQ |
153 | out: |
154 | return ret; | |
155 | } | |
156 | ||
e014ff8d ON |
157 | int ioprio_best(unsigned short aprio, unsigned short bprio) |
158 | { | |
ece9c72a | 159 | if (!ioprio_valid(aprio)) |
e70344c0 | 160 | aprio = IOPRIO_DEFAULT; |
ece9c72a | 161 | if (!ioprio_valid(bprio)) |
e70344c0 | 162 | bprio = IOPRIO_DEFAULT; |
e014ff8d | 163 | |
9a87182c | 164 | return min(aprio, bprio); |
e014ff8d ON |
165 | } |
166 | ||
938bb9f5 | 167 | SYSCALL_DEFINE2(ioprio_get, int, which, int, who) |
22e2c507 JA |
168 | { |
169 | struct task_struct *g, *p; | |
170 | struct user_struct *user; | |
41487c65 | 171 | struct pid *pgrp; |
7b44ab97 | 172 | kuid_t uid; |
22e2c507 | 173 | int ret = -ESRCH; |
a1836a42 | 174 | int tmpio; |
22e2c507 | 175 | |
d69b78ba | 176 | rcu_read_lock(); |
22e2c507 JA |
177 | switch (which) { |
178 | case IOPRIO_WHO_PROCESS: | |
179 | if (!who) | |
180 | p = current; | |
181 | else | |
228ebcbe | 182 | p = find_task_by_vpid(who); |
22e2c507 | 183 | if (p) |
a1836a42 | 184 | ret = get_task_ioprio(p); |
22e2c507 JA |
185 | break; |
186 | case IOPRIO_WHO_PGRP: | |
187 | if (!who) | |
41487c65 EB |
188 | pgrp = task_pgrp(current); |
189 | else | |
b488893a | 190 | pgrp = find_vpid(who); |
e6a59aac | 191 | read_lock(&tasklist_lock); |
2d70b68d | 192 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { |
a1836a42 DQ |
193 | tmpio = get_task_ioprio(p); |
194 | if (tmpio < 0) | |
195 | continue; | |
22e2c507 | 196 | if (ret == -ESRCH) |
a1836a42 | 197 | ret = tmpio; |
22e2c507 | 198 | else |
a1836a42 | 199 | ret = ioprio_best(ret, tmpio); |
2d70b68d | 200 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); |
e6a59aac DB |
201 | read_unlock(&tasklist_lock); |
202 | ||
22e2c507 JA |
203 | break; |
204 | case IOPRIO_WHO_USER: | |
7b44ab97 | 205 | uid = make_kuid(current_user_ns(), who); |
22e2c507 | 206 | if (!who) |
86a264ab | 207 | user = current_user(); |
22e2c507 | 208 | else |
7b44ab97 | 209 | user = find_user(uid); |
22e2c507 JA |
210 | |
211 | if (!user) | |
212 | break; | |
213 | ||
612dafab | 214 | for_each_process_thread(g, p) { |
8639b461 BS |
215 | if (!uid_eq(task_uid(p), user->uid) || |
216 | !task_pid_vnr(p)) | |
22e2c507 | 217 | continue; |
a1836a42 DQ |
218 | tmpio = get_task_ioprio(p); |
219 | if (tmpio < 0) | |
220 | continue; | |
22e2c507 | 221 | if (ret == -ESRCH) |
a1836a42 | 222 | ret = tmpio; |
22e2c507 | 223 | else |
a1836a42 | 224 | ret = ioprio_best(ret, tmpio); |
612dafab | 225 | } |
22e2c507 JA |
226 | |
227 | if (who) | |
228 | free_uid(user); | |
229 | break; | |
230 | default: | |
231 | ret = -EINVAL; | |
232 | } | |
233 | ||
d69b78ba | 234 | rcu_read_unlock(); |
22e2c507 JA |
235 | return ret; |
236 | } |