1#include <unistd.h>
2#include <sys/types.h>
3#include <fcntl.h>
4#include <stdlib.h>
5#include <stdio.h>
6#include <errno.h>
7#include <string.h>
8#include <limits.h>
9#include <ctype.h>
10#include "selinux_internal.h"
11#include "policy.h"
12#include "mapping.h"
13
14static int object_name_encode(const char *objname, char *buffer, size_t buflen)
15{
16	int	code;
17	size_t	offset = 0;
18
19	if (buflen - offset < 1)
20		return -1;
21	buffer[offset++] = ' ';
22
23	do {
24		code = *objname++;
25
26		if (isalnum(code) || code == '\0' || code == '-' ||
27		    code == '.' || code == '_' || code == '~') {
28			if (buflen - offset < 1)
29				return -1;
30			buffer[offset++] = code;
31		} else if (code == ' ') {
32			if (buflen - offset < 1)
33				return -1;
34			buffer[offset++] = '+';
35		} else {
36			static const char *table = "0123456789ABCDEF";
37			int	l = (code & 0x0f);
38			int	h = (code & 0xf0) >> 4;
39
40			if (buflen - offset < 3)
41				return -1;
42			buffer[offset++] = '%';
43			buffer[offset++] = table[h];
44			buffer[offset++] = table[l];
45		}
46	} while (code != '\0');
47
48	return 0;
49}
50
51int security_compute_create_name_raw(const char * scon,
52				     const char * tcon,
53				     security_class_t tclass,
54				     const char *objname,
55				     char ** newcon)
56{
57	char path[PATH_MAX];
58	char *buf;
59	size_t size;
60	int fd, ret, len;
61
62	if (!selinux_mnt) {
63		errno = ENOENT;
64		return -1;
65	}
66
67	snprintf(path, sizeof path, "%s/create", selinux_mnt);
68	fd = open(path, O_RDWR | O_CLOEXEC);
69	if (fd < 0)
70		return -1;
71
72	size = selinux_page_size;
73	buf = malloc(size);
74	if (!buf) {
75		ret = -1;
76		goto out;
77	}
78
79	len = snprintf(buf, size, "%s %s %hu",
80		       scon, tcon, unmap_class(tclass));
81	if (len < 0 || (size_t)len >= size) {
82		errno = EOVERFLOW;
83		ret = -1;
84		goto out2;
85	}
86
87	if (objname &&
88	    object_name_encode(objname, buf + len, size - len) < 0) {
89		errno = ENAMETOOLONG;
90		ret = -1;
91		goto out2;
92	}
93
94	ret = write(fd, buf, strlen(buf));
95	if (ret < 0)
96		goto out2;
97
98	memset(buf, 0, size);
99	ret = read(fd, buf, size - 1);
100	if (ret < 0)
101		goto out2;
102
103	*newcon = strdup(buf);
104	if (!(*newcon)) {
105		ret = -1;
106		goto out2;
107	}
108	ret = 0;
109      out2:
110	free(buf);
111      out:
112	close(fd);
113	return ret;
114}
115
116int security_compute_create_raw(const char * scon,
117				const char * tcon,
118				security_class_t tclass,
119				char ** newcon)
120{
121	return security_compute_create_name_raw(scon, tcon, tclass,
122						NULL, newcon);
123}
124
125int security_compute_create_name(const char * scon,
126				 const char * tcon,
127				 security_class_t tclass,
128				 const char *objname,
129				 char ** newcon)
130{
131	int ret;
132	char * rscon;
133	char * rtcon;
134	char * rnewcon;
135
136	if (selinux_trans_to_raw_context(scon, &rscon))
137		return -1;
138	if (selinux_trans_to_raw_context(tcon, &rtcon)) {
139		freecon(rscon);
140		return -1;
141	}
142
143	ret = security_compute_create_name_raw(rscon, rtcon, tclass,
144					       objname, &rnewcon);
145	freecon(rscon);
146	freecon(rtcon);
147	if (!ret) {
148		ret = selinux_raw_to_trans_context(rnewcon, newcon);
149		freecon(rnewcon);
150	}
151
152	return ret;
153}
154
155int security_compute_create(const char * scon,
156				const char * tcon,
157			    security_class_t tclass,
158				char ** newcon)
159{
160	return security_compute_create_name(scon, tcon, tclass, NULL, newcon);
161}
162