1 /*
2  * Copyright (c) 2022 Stefan Sperling <stsp@openbsd.org>
3  * Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <sys/types.h>
19 #include <sys/queue.h>
20 #include <sys/uio.h>
21 
22 #include <errno.h>
23 #include <event.h>
24 #include <grp.h>
25 #include <limits.h>
26 #include <pwd.h>
27 #include <grp.h>
28 #include <sha1.h>
29 #include <stdint.h>
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <imsg.h>
33 #include <unistd.h>
34 
35 #include "got_error.h"
36 
37 #include "gotd.h"
38 #include "log.h"
39 #include "auth.h"
40 
41 static int
42 parseuid(const char *s, uid_t *uid)
43 {
44 	struct passwd *pw;
45 	const char *errstr;
46 
47 	if ((pw = getpwnam(s)) != NULL) {
48 		*uid = pw->pw_uid;
49 		if (*uid == UID_MAX)
50 			return -1;
51 		return 0;
52 	}
53 	*uid = strtonum(s, 0, UID_MAX - 1, &errstr);
54 	if (errstr)
55 		return -1;
56 	return 0;
57 }
58 
59 static int
60 uidcheck(const char *s, uid_t desired)
61 {
62 	uid_t uid;
63 
64 	if (parseuid(s, &uid) != 0)
65 		return -1;
66 	if (uid != desired)
67 		return -1;
68 	return 0;
69 }
70 
71 static int
72 parsegid(const char *s, gid_t *gid)
73 {
74 	struct group *gr;
75 	const char *errstr;
76 
77 	if ((gr = getgrnam(s)) != NULL) {
78 		*gid = gr->gr_gid;
79 		if (*gid == GID_MAX)
80 			return -1;
81 		return 0;
82 	}
83 	*gid = strtonum(s, 0, GID_MAX - 1, &errstr);
84 	if (errstr)
85 		return -1;
86 	return 0;
87 }
88 
89 static int
90 match_identifier(const char *identifier, gid_t *groups, int ngroups,
91     uid_t euid, gid_t egid)
92 {
93 	int i;
94 
95 	if (identifier[0] == ':') {
96 		gid_t rgid;
97 		if (parsegid(identifier + 1, &rgid) == -1)
98 			return 0;
99 		if (rgid == egid)
100 			return 1;
101 		for (i = 0; i < ngroups; i++) {
102 			if (rgid == groups[i])
103 				break;
104 		}
105 		if (i == ngroups)
106 			return 0;
107 	} else if (uidcheck(identifier, euid) != 0)
108 		return 0;
109 
110 	return 1;
111 }
112 
113 const struct got_error *
114 gotd_auth_check(struct gotd_access_rule_list *rules, const char *repo_name,
115     uid_t euid, gid_t egid, int required_auth)
116 {
117 	struct gotd_access_rule *rule;
118 	enum gotd_access access = GOTD_ACCESS_DENIED;
119 	struct passwd *pw;
120 	gid_t groups[NGROUPS_MAX];
121 	int ngroups = NGROUPS_MAX;
122 
123 	pw = getpwuid(euid);
124 	if (pw == NULL)
125 		return got_error_from_errno("getpwuid");
126 
127 	if (getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups) == -1)
128 		log_warnx("group membership list truncated");
129 
130 	STAILQ_FOREACH(rule, rules, entry) {
131 		if (!match_identifier(rule->identifier, groups, ngroups,
132 		    euid, egid))
133 			continue;
134 
135 		access = rule->access;
136 		if (rule->access == GOTD_ACCESS_PERMITTED &&
137 		    (rule->authorization & required_auth) != required_auth)
138 			access = GOTD_ACCESS_DENIED;
139 	}
140 
141 	if (access == GOTD_ACCESS_DENIED)
142 		return got_error_set_errno(EACCES, repo_name);
143 
144 	if (access == GOTD_ACCESS_PERMITTED)
145 		return NULL;
146 
147 	/* should not happen, this would be a bug */
148 	return got_error_msg(GOT_ERR_NOT_IMPL, "bad access rule");
149 }