1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Helper functions for handling target threads/cpus
4  *
5  * Copyright (C) 2012, LG Electronics, Namhyung Kim <namhyung.kim@lge.com>
6  */
7 
8 #include "target.h"
9 
10 #include <pwd.h>
11 #include <stdio.h>
12 #include <stdlib.h>
13 #include <string.h>
14 #include <linux/kernel.h>
15 #include <linux/string.h>
16 
target__validate(struct target * target)17 enum target_errno target__validate(struct target *target)
18 {
19 	enum target_errno ret = TARGET_ERRNO__SUCCESS;
20 
21 	if (target->pid)
22 		target->tid = target->pid;
23 
24 	/* CPU and PID are mutually exclusive */
25 	if (target->tid && target->cpu_list) {
26 		target->cpu_list = NULL;
27 		if (ret == TARGET_ERRNO__SUCCESS)
28 			ret = TARGET_ERRNO__PID_OVERRIDE_CPU;
29 	}
30 
31 	/* UID and PID are mutually exclusive */
32 	if (target->tid && target->uid_str) {
33 		target->uid_str = NULL;
34 		if (ret == TARGET_ERRNO__SUCCESS)
35 			ret = TARGET_ERRNO__PID_OVERRIDE_UID;
36 	}
37 
38 	/* UID and CPU are mutually exclusive */
39 	if (target->uid_str && target->cpu_list) {
40 		target->cpu_list = NULL;
41 		if (ret == TARGET_ERRNO__SUCCESS)
42 			ret = TARGET_ERRNO__UID_OVERRIDE_CPU;
43 	}
44 
45 	/* PID and SYSTEM are mutually exclusive */
46 	if (target->tid && target->system_wide) {
47 		target->system_wide = false;
48 		if (ret == TARGET_ERRNO__SUCCESS)
49 			ret = TARGET_ERRNO__PID_OVERRIDE_SYSTEM;
50 	}
51 
52 	/* UID and SYSTEM are mutually exclusive */
53 	if (target->uid_str && target->system_wide) {
54 		target->system_wide = false;
55 		if (ret == TARGET_ERRNO__SUCCESS)
56 			ret = TARGET_ERRNO__UID_OVERRIDE_SYSTEM;
57 	}
58 
59 	/* BPF and CPU are mutually exclusive */
60 	if (target->bpf_str && target->cpu_list) {
61 		target->cpu_list = NULL;
62 		if (ret == TARGET_ERRNO__SUCCESS)
63 			ret = TARGET_ERRNO__BPF_OVERRIDE_CPU;
64 	}
65 
66 	/* BPF and PID/TID are mutually exclusive */
67 	if (target->bpf_str && target->tid) {
68 		target->tid = NULL;
69 		if (ret == TARGET_ERRNO__SUCCESS)
70 			ret = TARGET_ERRNO__BPF_OVERRIDE_PID;
71 	}
72 
73 	/* BPF and UID are mutually exclusive */
74 	if (target->bpf_str && target->uid_str) {
75 		target->uid_str = NULL;
76 		if (ret == TARGET_ERRNO__SUCCESS)
77 			ret = TARGET_ERRNO__BPF_OVERRIDE_UID;
78 	}
79 
80 	/* BPF and THREADS are mutually exclusive */
81 	if (target->bpf_str && target->per_thread) {
82 		target->per_thread = false;
83 		if (ret == TARGET_ERRNO__SUCCESS)
84 			ret = TARGET_ERRNO__BPF_OVERRIDE_THREAD;
85 	}
86 
87 	/* THREAD and SYSTEM/CPU are mutually exclusive */
88 	if (target->per_thread && (target->system_wide || target->cpu_list)) {
89 		target->per_thread = false;
90 		if (ret == TARGET_ERRNO__SUCCESS)
91 			ret = TARGET_ERRNO__SYSTEM_OVERRIDE_THREAD;
92 	}
93 
94 	return ret;
95 }
96 
target__parse_uid(struct target * target)97 enum target_errno target__parse_uid(struct target *target)
98 {
99 	struct passwd pwd, *result;
100 	char buf[1024];
101 	const char *str = target->uid_str;
102 
103 	target->uid = UINT_MAX;
104 	if (str == NULL)
105 		return TARGET_ERRNO__SUCCESS;
106 
107 	/* Try user name first */
108 	getpwnam_r(str, &pwd, buf, sizeof(buf), &result);
109 
110 	if (result == NULL) {
111 		/*
112 		 * The user name not found. Maybe it's a UID number.
113 		 */
114 		char *endptr;
115 		int uid = strtol(str, &endptr, 10);
116 
117 		if (*endptr != '\0')
118 			return TARGET_ERRNO__INVALID_UID;
119 
120 		getpwuid_r(uid, &pwd, buf, sizeof(buf), &result);
121 
122 		if (result == NULL)
123 			return TARGET_ERRNO__USER_NOT_FOUND;
124 	}
125 
126 	target->uid = result->pw_uid;
127 	return TARGET_ERRNO__SUCCESS;
128 }
129 
130 /*
131  * This must have a same ordering as the enum target_errno.
132  */
133 static const char *target__error_str[] = {
134 	"PID/TID switch overriding CPU",
135 	"PID/TID switch overriding UID",
136 	"UID switch overriding CPU",
137 	"PID/TID switch overriding SYSTEM",
138 	"UID switch overriding SYSTEM",
139 	"SYSTEM/CPU switch overriding PER-THREAD",
140 	"BPF switch overriding CPU",
141 	"BPF switch overriding PID/TID",
142 	"BPF switch overriding UID",
143 	"BPF switch overriding THREAD",
144 	"Invalid User: %s",
145 	"Problems obtaining information for user %s",
146 };
147 
target__strerror(struct target * target,int errnum,char * buf,size_t buflen)148 int target__strerror(struct target *target, int errnum,
149 			  char *buf, size_t buflen)
150 {
151 	int idx;
152 	const char *msg;
153 
154 	BUG_ON(buflen == 0);
155 
156 	if (errnum >= 0) {
157 		str_error_r(errnum, buf, buflen);
158 		return 0;
159 	}
160 
161 	if (errnum <  __TARGET_ERRNO__START || errnum >= __TARGET_ERRNO__END)
162 		return -1;
163 
164 	idx = errnum - __TARGET_ERRNO__START;
165 	msg = target__error_str[idx];
166 
167 	switch (errnum) {
168 	case TARGET_ERRNO__PID_OVERRIDE_CPU ...
169 	     TARGET_ERRNO__BPF_OVERRIDE_THREAD:
170 		snprintf(buf, buflen, "%s", msg);
171 		break;
172 
173 	case TARGET_ERRNO__INVALID_UID:
174 	case TARGET_ERRNO__USER_NOT_FOUND:
175 		snprintf(buf, buflen, msg, target->uid_str);
176 		break;
177 
178 	default:
179 		/* cannot reach here */
180 		break;
181 	}
182 
183 	return 0;
184 }
185