1 /* Test for access to file, relative to open directory. Hurd version.
2 Copyright (C) 2006-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <errno.h>
20 #include <fcntl.h>
21 #include <stddef.h>
22 #include <unistd.h>
23 #include <sys/types.h>
24 #include <hurd.h>
25 #include <hurd/fd.h>
26 #include <hurd/port.h>
27 #include <hurd/id.h>
28 #include <hurd/lookup.h>
29
30 static int
31 hurd_fail_seterrno (error_t err)
32 {
33 return __hurd_fail (err);
34 }
35
36 static int
37 hurd_fail_noerrno (error_t err)
38 {
39 return -1;
40 }
41
42 static int
43 __faccessat_common (int fd, const char *file, int type, int at_flags,
44 int (*errfunc) (error_t))
45 {
46 error_t err;
47 file_t rcrdir, rcwdir, io;
48 int flags, allowed;
49
50 if ((at_flags & AT_EACCESS) == AT_EACCESS)
51 {
52 /* Use effective permissions. */
53 io = __file_name_lookup_at (fd, at_flags &~ AT_EACCESS, file, 0, 0);
54 if (io == MACH_PORT_NULL)
55 return -1;
56 }
57 else
58 {
59 /* We have to use real permissions instead of the
60 usual effective permissions. */
61
62 int hurd_flags = 0;
63 err = __hurd_at_flags (&at_flags, &hurd_flags);
64 if (err)
65 return errfunc (err);
66
67 error_t reauthenticate_cwdir_at (file_t *result)
68 {
69 /* Get a port to the FD directory, authenticated with the real IDs. */
70 error_t err;
71 mach_port_t ref;
72 ref = __mach_reply_port ();
73 err = HURD_DPORT_USE
74 (fd,
75 ({
76 err = __io_reauthenticate (port, ref, MACH_MSG_TYPE_MAKE_SEND);
77 if (!err)
78 err = __auth_user_authenticate (_hurd_id.rid_auth,
79 ref, MACH_MSG_TYPE_MAKE_SEND,
80 result);
81 err;
82 }));
83 __mach_port_destroy (__mach_task_self (), ref);
84 return err;
85 }
86
87 error_t reauthenticate (int which, file_t *result)
88 {
89 /* Get a port to our root directory, authenticated with the real IDs. */
90 error_t err;
91 mach_port_t ref;
92 ref = __mach_reply_port ();
93 err = HURD_PORT_USE
94 (&_hurd_ports[which],
95 ({
96 err = __io_reauthenticate (port, ref, MACH_MSG_TYPE_MAKE_SEND);
97 if (!err)
98 err = __auth_user_authenticate (_hurd_id.rid_auth,
99 ref, MACH_MSG_TYPE_MAKE_SEND,
100 result);
101 err;
102 }));
103 __mach_port_destroy (__mach_task_self (), ref);
104 return err;
105 }
106
107 error_t init_port (int which, error_t (*operate) (mach_port_t))
108 {
109 switch (which)
110 {
111 case INIT_PORT_AUTH:
112 return (*operate) (_hurd_id.rid_auth);
113 case INIT_PORT_CRDIR:
114 return (reauthenticate (INIT_PORT_CRDIR, &rcrdir) ?:
115 (*operate) (rcrdir));
116 case INIT_PORT_CWDIR:
117 if (fd == AT_FDCWD || file[0] == '/')
118 return (reauthenticate (INIT_PORT_CWDIR, &rcwdir) ?:
119 (*operate) (rcwdir));
120 else
121 return (reauthenticate_cwdir_at (&rcwdir) ?:
122 (*operate) (rcwdir));
123 default:
124 return _hurd_ports_use (which, operate);
125 }
126 }
127
128 rcrdir = rcwdir = MACH_PORT_NULL;
129
130 retry:
131 HURD_CRITICAL_BEGIN;
132
133 __mutex_lock (&_hurd_id.lock);
134 /* Get _hurd_id up to date. */
135 if (err = _hurd_check_ids ())
136 goto lose;
137
138 if (_hurd_id.rid_auth == MACH_PORT_NULL)
139 {
140 /* Set up _hurd_id.rid_auth. This is a special auth server port
141 which uses the real uid and gid (the first aux uid and gid) as
142 the only effective uid and gid. */
143
144 if (_hurd_id.aux.nuids < 1 || _hurd_id.aux.ngids < 1)
145 {
146 /* We do not have a real UID and GID. Lose, lose, lose! */
147 err = EGRATUITOUS;
148 goto lose;
149 }
150
151 /* Create a new auth port using our real UID and GID (the first
152 auxiliary UID and GID) as the only effective IDs. */
153 if (err = __USEPORT (AUTH,
154 __auth_makeauth (port,
155 NULL, MACH_MSG_TYPE_COPY_SEND, 0,
156 _hurd_id.aux.uids, 1,
157 _hurd_id.aux.uids,
158 _hurd_id.aux.nuids,
159 _hurd_id.aux.gids, 1,
160 _hurd_id.aux.gids,
161 _hurd_id.aux.ngids,
162 &_hurd_id.rid_auth)))
163 goto lose;
164 }
165
166 if (!err)
167 /* Look up the file name using the modified init ports. */
168 err = __hurd_file_name_lookup (&init_port, &__getdport, 0,
169 file, hurd_flags, 0, &io);
170
171 /* We are done with _hurd_id.rid_auth now. */
172 lose:
173 __mutex_unlock (&_hurd_id.lock);
174
175 HURD_CRITICAL_END;
176 if (err == EINTR)
177 /* Got a signal while inside an RPC of the critical section, retry again */
178 goto retry;
179
180 if (rcrdir != MACH_PORT_NULL)
181 __mach_port_deallocate (__mach_task_self (), rcrdir);
182 if (rcwdir != MACH_PORT_NULL)
183 __mach_port_deallocate (__mach_task_self (), rcwdir);
184 if (err)
185 return errfunc (err);
186 }
187
188 /* Find out what types of access we are allowed to this file. */
189 err = __file_check_access (io, &allowed);
190 __mach_port_deallocate (__mach_task_self (), io);
191 if (err)
192 return errfunc (err);
193
194 flags = 0;
195 if (type & R_OK)
196 flags |= O_READ;
197 if (type & W_OK)
198 flags |= O_WRITE;
199 if (type & X_OK)
200 flags |= O_EXEC;
201
202 if (flags & ~allowed)
203 /* We are not allowed all the requested types of access. */
204 return errfunc (EACCES);
205
206 return 0;
207 }
208
209 int
210 __faccessat_noerrno (int fd, const char *file, int type, int at_flags)
211 {
212 return __faccessat_common (fd, file, type, at_flags, hurd_fail_noerrno);
213 }
214
215 int
216 __faccessat (int fd, const char *file, int type, int at_flags)
217 {
218 return __faccessat_common (fd, file, type, at_flags, hurd_fail_seterrno);
219 }
220 weak_alias (__faccessat, faccessat)