1 #include "context_internal.h"
2 #include <string.h>
3 #include <stdio.h>
4 #include <stdlib.h>
5 #include <errno.h>
6
7 #define COMP_USER 0
8 #define COMP_ROLE 1
9 #define COMP_TYPE 2
10 #define COMP_RANGE 3
11
12 typedef struct {
13 char *current_str; /* This is made up-to-date only when needed */
14 char *(component[4]);
15 } context_private_t;
16
17 /*
18 * Allocate a new context, initialized from str. There must be 3 or
19 * 4 colon-separated components and no whitespace in any component other
20 * than the MLS component.
21 */
context_new(const char * str)22 context_t context_new(const char *str)
23 {
24 int i, count;
25 errno = 0;
26 context_private_t *n =
27 (context_private_t *) malloc(sizeof(context_private_t));
28 context_t result = (context_t) malloc(sizeof(context_s_t));
29 const char *p, *tok;
30
31 if (result)
32 result->ptr = n;
33 else
34 free(n);
35 if (n == 0 || result == 0) {
36 goto err;
37 }
38 n->current_str = n->component[0] = n->component[1] = n->component[2] =
39 n->component[3] = 0;
40 for (count = 0, p = str; *p; p++) {
41 switch (*p) {
42 case ':':
43 count++;
44 break;
45 case '\n':
46 case '\t':
47 case '\r':
48 goto err; /* sanity check */
49 case ' ':
50 if (count < 3)
51 goto err; /* sanity check */
52 }
53 }
54 /*
55 * Could be anywhere from 2 - 5
56 * e.g user:role:type to user:role:type:sens1:cata-sens2:catb
57 */
58 if (count < 2 || count > 5) { /* might not have a range */
59 goto err;
60 }
61
62 n->component[3] = 0;
63 for (i = 0, tok = str; *tok; i++) {
64 if (i < 3)
65 for (p = tok; *p && *p != ':'; p++) { /* empty */
66 } else {
67 /* MLS range is one component */
68 for (p = tok; *p; p++) { /* empty */
69 }
70 }
71 n->component[i] = strndup(tok, p - tok);
72 if (n->component[i] == 0)
73 goto err;
74 tok = *p ? p + 1 : p;
75 }
76 return result;
77 err:
78 if (errno == 0) errno = EINVAL;
79 context_free(result);
80 return 0;
81 }
82
83
conditional_free(char ** v)84 static void conditional_free(char **v)
85 {
86 if (*v) {
87 free(*v);
88 }
89 *v = 0;
90 }
91
92 /*
93 * free all storage used by a context. Safe to call with
94 * null pointer.
95 */
context_free(context_t context)96 void context_free(context_t context)
97 {
98 context_private_t *n;
99 int i;
100 if (context) {
101 n = context->ptr;
102 if (n) {
103 conditional_free(&n->current_str);
104 for (i = 0; i < 4; i++) {
105 conditional_free(&n->component[i]);
106 }
107 free(n);
108 }
109 free(context);
110 }
111 }
112
113
114 /*
115 * Return a pointer to the string value of the context.
116 */
context_str(context_t context)117 const char *context_str(context_t context)
118 {
119 context_private_t *n = context->ptr;
120 int i;
121 size_t total = 0;
122 conditional_free(&n->current_str);
123 for (i = 0; i < 4; i++) {
124 if (n->component[i]) {
125 total += strlen(n->component[i]) + 1;
126 }
127 }
128 n->current_str = malloc(total);
129 if (n->current_str != 0) {
130 char *cp = n->current_str;
131
132 cp = stpcpy(cp, n->component[0]);
133 for (i = 1; i < 4; i++) {
134 if (n->component[i]) {
135 *cp++ = ':';
136 cp = stpcpy(cp, n->component[i]);
137 }
138 }
139 }
140 return n->current_str;
141 }
142
143
144 /* Returns nonzero iff failed */
set_comp(context_private_t * n,int idx,const char * str)145 static int set_comp(context_private_t * n, int idx, const char *str)
146 {
147 char *t = NULL;
148 const char *p;
149 if (str) {
150 for (p = str; *p; p++) {
151 if (*p == '\t' || *p == '\n' || *p == '\r' ||
152 ((*p == ':' || *p == ' ') && idx != COMP_RANGE)) {
153 errno = EINVAL;
154 return -1;
155 }
156 }
157
158 t = strdup(str);
159 if (!t) {
160 return -1;
161 }
162 }
163 conditional_free(&n->component[idx]);
164 n->component[idx] = t;
165 return 0;
166 }
167
168 #define def_get(name,tag) \
169 const char * context_ ## name ## _get(context_t context) \
170 { \
171 context_private_t *n = context->ptr; \
172 return n->component[tag]; \
173 }
174
175 def_get(type, COMP_TYPE)
176 def_get(user, COMP_USER)
177 def_get(range, COMP_RANGE)
178 def_get(role, COMP_ROLE)
179 #define def_set(name,tag) \
180 int context_ ## name ## _set(context_t context, const char* str) \
181 { \
182 return set_comp(context->ptr,tag,str);\
183 }
184 def_set(type, COMP_TYPE)
185 def_set(role, COMP_ROLE)
186 def_set(user, COMP_USER)
187 def_set(range, COMP_RANGE)
188