1 | /* Test for access to file, relative to open directory. Hurd version. |
2 | Copyright (C) 2006-2022 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, errfunc: 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, errfunc: hurd_fail_seterrno); |
219 | } |
220 | weak_alias (__faccessat, faccessat) |
221 | |