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/* $OpenBSD: doas.c,v 1.72 2017/05/27 09:51:07 tedu Exp $ */ |
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/* |
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* Copyright (c) 2015 Ted Unangst <tedu@openbsd.org> |
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* |
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* Permission to use, copy, modify, and distribute this software for any |
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* purpose with or without fee is hereby granted, provided that the above |
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* copyright notice and this permission notice appear in all copies. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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*/ |
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#include <sys/types.h> |
19 |
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#include <sys/stat.h> |
20 |
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#include <sys/ioctl.h> |
21 |
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22 |
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#include <limits.h> |
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#include <login_cap.h> |
24 |
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#include <bsd_auth.h> |
25 |
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#include <readpassphrase.h> |
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#include <string.h> |
27 |
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#include <stdio.h> |
28 |
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#include <stdlib.h> |
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#include <err.h> |
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#include <unistd.h> |
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#include <pwd.h> |
32 |
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#include <grp.h> |
33 |
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#include <syslog.h> |
34 |
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#include <errno.h> |
35 |
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#include <fcntl.h> |
36 |
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37 |
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#include "doas.h" |
38 |
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39 |
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static void __dead |
40 |
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usage(void) |
41 |
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{ |
42 |
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fprintf(stderr, "usage: doas [-Lns] [-a style] [-C config] [-u user]" |
43 |
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" command [args]\n"); |
44 |
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exit(1); |
45 |
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} |
46 |
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47 |
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static int |
48 |
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parseuid(const char *s, uid_t *uid) |
49 |
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{ |
50 |
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struct passwd *pw; |
51 |
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const char *errstr; |
52 |
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53 |
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if ((pw = getpwnam(s)) != NULL) { |
54 |
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*uid = pw->pw_uid; |
55 |
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return 0; |
56 |
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} |
57 |
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*uid = strtonum(s, 0, UID_MAX, &errstr); |
58 |
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if (errstr) |
59 |
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return -1; |
60 |
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return 0; |
61 |
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} |
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static int |
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uidcheck(const char *s, uid_t desired) |
65 |
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{ |
66 |
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uid_t uid; |
67 |
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68 |
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if (parseuid(s, &uid) != 0) |
69 |
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return -1; |
70 |
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if (uid != desired) |
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return -1; |
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return 0; |
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} |
74 |
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75 |
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static int |
76 |
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parsegid(const char *s, gid_t *gid) |
77 |
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{ |
78 |
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struct group *gr; |
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const char *errstr; |
80 |
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81 |
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if ((gr = getgrnam(s)) != NULL) { |
82 |
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*gid = gr->gr_gid; |
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return 0; |
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} |
85 |
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*gid = strtonum(s, 0, GID_MAX, &errstr); |
86 |
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if (errstr) |
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return -1; |
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return 0; |
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} |
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static int |
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match(uid_t uid, gid_t *groups, int ngroups, uid_t target, const char *cmd, |
93 |
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const char **cmdargs, struct rule *r) |
94 |
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{ |
95 |
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int i; |
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97 |
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if (r->ident[0] == ':') { |
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gid_t rgid; |
99 |
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if (parsegid(r->ident + 1, &rgid) == -1) |
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return 0; |
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for (i = 0; i < ngroups; i++) { |
102 |
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if (rgid == groups[i]) |
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break; |
104 |
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} |
105 |
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if (i == ngroups) |
106 |
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return 0; |
107 |
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} else { |
108 |
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if (uidcheck(r->ident, uid) != 0) |
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return 0; |
110 |
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} |
111 |
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if (r->target && uidcheck(r->target, target) != 0) |
112 |
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return 0; |
113 |
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if (r->cmd) { |
114 |
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if (strcmp(r->cmd, cmd)) |
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return 0; |
116 |
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if (r->cmdargs) { |
117 |
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/* if arguments were given, they should match explicitly */ |
118 |
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for (i = 0; r->cmdargs[i]; i++) { |
119 |
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if (!cmdargs[i]) |
120 |
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return 0; |
121 |
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if (strcmp(r->cmdargs[i], cmdargs[i])) |
122 |
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return 0; |
123 |
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} |
124 |
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if (cmdargs[i]) |
125 |
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return 0; |
126 |
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} |
127 |
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} |
128 |
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return 1; |
129 |
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} |
130 |
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131 |
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static int |
132 |
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permit(uid_t uid, gid_t *groups, int ngroups, const struct rule **lastr, |
133 |
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uid_t target, const char *cmd, const char **cmdargs) |
134 |
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{ |
135 |
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int i; |
136 |
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137 |
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*lastr = NULL; |
138 |
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for (i = 0; i < nrules; i++) { |
139 |
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if (match(uid, groups, ngroups, target, cmd, |
140 |
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cmdargs, rules[i])) |
141 |
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*lastr = rules[i]; |
142 |
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} |
143 |
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if (!*lastr) |
144 |
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return 0; |
145 |
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return (*lastr)->action == PERMIT; |
146 |
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} |
147 |
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148 |
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static void |
149 |
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parseconfig(const char *filename, int checkperms) |
150 |
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{ |
151 |
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extern FILE *yyfp; |
152 |
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extern int yyparse(void); |
153 |
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struct stat sb; |
154 |
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155 |
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yyfp = fopen(filename, "r"); |
156 |
✗✓ |
18 |
if (!yyfp) |
157 |
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err(1, checkperms ? "doas is not enabled, %s" : |
158 |
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"could not open config file %s", filename); |
159 |
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160 |
✗✓ |
18 |
if (checkperms) { |
161 |
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if (fstat(fileno(yyfp), &sb) != 0) |
162 |
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err(1, "fstat(\"%s\")", filename); |
163 |
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if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
164 |
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errx(1, "%s is writable by group or other", filename); |
165 |
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if (sb.st_uid != 0) |
166 |
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errx(1, "%s is not owned by root", filename); |
167 |
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} |
168 |
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169 |
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yyparse(); |
170 |
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fclose(yyfp); |
171 |
✓✓ |
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if (parse_errors) |
172 |
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exit(1); |
173 |
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9 |
} |
174 |
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static void __dead |
176 |
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checkconfig(const char *confpath, int argc, char **argv, |
177 |
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uid_t uid, gid_t *groups, int ngroups, uid_t target) |
178 |
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{ |
179 |
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27 |
const struct rule *rule; |
180 |
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181 |
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setresuid(uid, uid, uid); |
182 |
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parseconfig(confpath, 0); |
183 |
✓✗ |
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if (!argc) |
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exit(0); |
185 |
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186 |
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if (permit(uid, groups, ngroups, &rule, target, argv[0], |
187 |
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(const char **)argv + 1)) { |
188 |
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printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : ""); |
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exit(0); |
190 |
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} else { |
191 |
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printf("deny\n"); |
192 |
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exit(1); |
193 |
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} |
194 |
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} |
195 |
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196 |
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static void |
197 |
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authuser(char *myname, char *login_style, int persist) |
198 |
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{ |
199 |
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char *challenge = NULL, *response, rbuf[1024], cbuf[128]; |
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auth_session_t *as; |
201 |
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int fd = -1; |
202 |
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203 |
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if (persist) |
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fd = open("/dev/tty", O_RDWR); |
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if (fd != -1) { |
206 |
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if (ioctl(fd, TIOCCHKVERAUTH) == 0) |
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goto good; |
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} |
209 |
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210 |
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if (!(as = auth_userchallenge(myname, login_style, "auth-doas", |
211 |
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&challenge))) |
212 |
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errx(1, "Authorization failed"); |
213 |
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if (!challenge) { |
214 |
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char host[HOST_NAME_MAX + 1]; |
215 |
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if (gethostname(host, sizeof(host))) |
216 |
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snprintf(host, sizeof(host), "?"); |
217 |
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snprintf(cbuf, sizeof(cbuf), |
218 |
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"\rdoas (%.32s@%.32s) password: ", myname, host); |
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challenge = cbuf; |
220 |
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} |
221 |
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response = readpassphrase(challenge, rbuf, sizeof(rbuf), |
222 |
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RPP_REQUIRE_TTY); |
223 |
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if (response == NULL && errno == ENOTTY) { |
224 |
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syslog(LOG_AUTHPRIV | LOG_NOTICE, |
225 |
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"tty required for %s", myname); |
226 |
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errx(1, "a tty is required"); |
227 |
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} |
228 |
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if (!auth_userresponse(as, response, 0)) { |
229 |
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syslog(LOG_AUTHPRIV | LOG_NOTICE, |
230 |
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"failed auth for %s", myname); |
231 |
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errx(1, "Authorization failed"); |
232 |
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} |
233 |
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explicit_bzero(rbuf, sizeof(rbuf)); |
234 |
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good: |
235 |
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if (fd != -1) { |
236 |
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int secs = 5 * 60; |
237 |
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ioctl(fd, TIOCSETVERAUTH, &secs); |
238 |
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close(fd); |
239 |
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} |
240 |
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} |
241 |
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242 |
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int |
243 |
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main(int argc, char **argv) |
244 |
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{ |
245 |
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const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:" |
246 |
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"/usr/local/bin:/usr/local/sbin"; |
247 |
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const char *confpath = NULL; |
248 |
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36 |
char *shargv[] = { NULL, NULL }; |
249 |
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char *sh; |
250 |
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const char *cmd; |
251 |
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18 |
char cmdline[LINE_MAX]; |
252 |
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18 |
char myname[_PW_NAME_LEN + 1]; |
253 |
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struct passwd *pw; |
254 |
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18 |
const struct rule *rule; |
255 |
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uid_t uid; |
256 |
|
18 |
uid_t target = 0; |
257 |
|
18 |
gid_t groups[NGROUPS_MAX + 1]; |
258 |
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int ngroups; |
259 |
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int i, ch; |
260 |
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int sflag = 0; |
261 |
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int nflag = 0; |
262 |
|
18 |
char cwdpath[PATH_MAX]; |
263 |
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const char *cwd; |
264 |
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char *login_style = NULL; |
265 |
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char **envp; |
266 |
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267 |
|
18 |
setprogname("doas"); |
268 |
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269 |
|
18 |
closefrom(STDERR_FILENO + 1); |
270 |
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271 |
|
18 |
uid = getuid(); |
272 |
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|
273 |
✓✓ |
54 |
while ((ch = getopt(argc, argv, "a:C:Lnsu:")) != -1) { |
274 |
✗✓✗✗ ✗✗✗ |
18 |
switch (ch) { |
275 |
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case 'a': |
276 |
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login_style = optarg; |
277 |
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break; |
278 |
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case 'C': |
279 |
|
18 |
confpath = optarg; |
280 |
|
18 |
break; |
281 |
|
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case 'L': |
282 |
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i = open("/dev/tty", O_RDWR); |
283 |
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if (i != -1) |
284 |
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ioctl(i, TIOCCLRVERAUTH); |
285 |
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exit(i == -1); |
286 |
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case 'u': |
287 |
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if (parseuid(optarg, &target) != 0) |
288 |
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errx(1, "unknown user"); |
289 |
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break; |
290 |
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case 'n': |
291 |
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nflag = 1; |
292 |
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break; |
293 |
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case 's': |
294 |
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sflag = 1; |
295 |
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break; |
296 |
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default: |
297 |
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usage(); |
298 |
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break; |
299 |
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} |
300 |
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} |
301 |
|
18 |
argv += optind; |
302 |
|
18 |
argc -= optind; |
303 |
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|
304 |
✓✗ |
18 |
if (confpath) { |
305 |
✗✓ |
18 |
if (sflag) |
306 |
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usage(); |
307 |
|
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} else if ((!sflag && !argc) || (sflag && argc)) |
308 |
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usage(); |
309 |
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|
310 |
|
18 |
pw = getpwuid(uid); |
311 |
✗✓ |
18 |
if (!pw) |
312 |
|
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err(1, "getpwuid failed"); |
313 |
✗✓ |
18 |
if (strlcpy(myname, pw->pw_name, sizeof(myname)) >= sizeof(myname)) |
314 |
|
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errx(1, "pw_name too long"); |
315 |
|
18 |
ngroups = getgroups(NGROUPS_MAX, groups); |
316 |
✗✓ |
18 |
if (ngroups == -1) |
317 |
|
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err(1, "can't get groups"); |
318 |
|
18 |
groups[ngroups++] = getgid(); |
319 |
|
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|
320 |
✗✓ |
18 |
if (sflag) { |
321 |
|
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sh = getenv("SHELL"); |
322 |
|
|
if (sh == NULL || *sh == '\0') { |
323 |
|
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shargv[0] = strdup(pw->pw_shell); |
324 |
|
|
if (shargv[0] == NULL) |
325 |
|
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err(1, NULL); |
326 |
|
|
} else |
327 |
|
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shargv[0] = sh; |
328 |
|
|
argv = shargv; |
329 |
|
|
argc = 1; |
330 |
|
|
} |
331 |
|
|
|
332 |
✓✗ |
18 |
if (confpath) { |
333 |
|
|
checkconfig(confpath, argc, argv, uid, groups, ngroups, |
334 |
|
|
target); |
335 |
|
|
exit(1); /* fail safe */ |
336 |
|
|
} |
337 |
|
|
|
338 |
|
|
if (geteuid()) |
339 |
|
|
errx(1, "not installed setuid"); |
340 |
|
|
|
341 |
|
|
parseconfig("/etc/doas.conf", 1); |
342 |
|
|
|
343 |
|
|
/* cmdline is used only for logging, no need to abort on truncate */ |
344 |
|
|
(void)strlcpy(cmdline, argv[0], sizeof(cmdline)); |
345 |
|
|
for (i = 1; i < argc; i++) { |
346 |
|
|
if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline)) |
347 |
|
|
break; |
348 |
|
|
if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline)) |
349 |
|
|
break; |
350 |
|
|
} |
351 |
|
|
|
352 |
|
|
cmd = argv[0]; |
353 |
|
|
if (!permit(uid, groups, ngroups, &rule, target, cmd, |
354 |
|
|
(const char **)argv + 1)) { |
355 |
|
|
syslog(LOG_AUTHPRIV | LOG_NOTICE, |
356 |
|
|
"failed command for %s: %s", myname, cmdline); |
357 |
|
|
errc(1, EPERM, NULL); |
358 |
|
|
} |
359 |
|
|
|
360 |
|
|
if (!(rule->options & NOPASS)) { |
361 |
|
|
if (nflag) |
362 |
|
|
errx(1, "Authorization required"); |
363 |
|
|
|
364 |
|
|
authuser(myname, login_style, rule->options & PERSIST); |
365 |
|
|
} |
366 |
|
|
|
367 |
|
|
if (pledge("stdio rpath getpw exec id flock cpath wpath", NULL) == -1) |
368 |
|
|
err(1, "pledge"); |
369 |
|
|
|
370 |
|
|
pw = getpwuid(target); |
371 |
|
|
if (!pw) |
372 |
|
|
errx(1, "no passwd entry for target"); |
373 |
|
|
|
374 |
|
|
if (setusercontext(NULL, pw, target, LOGIN_SETGROUP | |
375 |
|
|
LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK | |
376 |
|
|
LOGIN_SETUSER) != 0) |
377 |
|
|
errx(1, "failed to set user context for target"); |
378 |
|
|
|
379 |
|
|
if (pledge("stdio rpath exec flock cpath wpath", NULL) == -1) |
380 |
|
|
err(1, "pledge"); |
381 |
|
|
|
382 |
|
|
if (getcwd(cwdpath, sizeof(cwdpath)) == NULL) |
383 |
|
|
cwd = "(failed)"; |
384 |
|
|
else |
385 |
|
|
cwd = cwdpath; |
386 |
|
|
|
387 |
|
|
if (pledge("stdio exec flock rpath cpath wpath", NULL) == -1) |
388 |
|
|
err(1, "pledge"); |
389 |
|
|
|
390 |
|
|
syslog(LOG_AUTHPRIV | LOG_INFO, "%s ran command %s as %s from %s", |
391 |
|
|
myname, cmdline, pw->pw_name, cwd); |
392 |
|
|
|
393 |
|
|
envp = prepenv(rule); |
394 |
|
|
|
395 |
|
|
if (rule->cmd) { |
396 |
|
|
if (setenv("PATH", safepath, 1) == -1) |
397 |
|
|
err(1, "failed to set PATH '%s'", safepath); |
398 |
|
|
} |
399 |
|
|
execvpe(cmd, argv, envp); |
400 |
|
|
if (errno == ENOENT) |
401 |
|
|
errx(1, "%s: command not found", cmd); |
402 |
|
|
err(1, "%s", cmd); |
403 |
|
|
} |