1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
|
/* euidaccess -- check if effective user id can access file
Copyright (C) 1990, 1991, 1995 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
/* Written by David MacKenzie and Torbjorn Granlund.
Adapted for GNU C library by Roland McGrath. */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#ifdef S_IEXEC
#ifndef S_IXUSR
#define S_IXUSR S_IEXEC
#endif
#ifndef S_IXGRP
#define S_IXGRP (S_IEXEC >> 3)
#endif
#ifndef S_IXOTH
#define S_IXOTH (S_IEXEC >> 6)
#endif
#endif /* S_IEXEC */
#if defined (HAVE_UNISTD_H) || defined (_LIBC)
#include <unistd.h>
#endif
#ifdef _POSIX_VERSION
#include <limits.h>
#if !defined(NGROUPS_MAX) || NGROUPS_MAX < 1
#undef NGROUPS_MAX
#define NGROUPS_MAX sysconf (_SC_NGROUPS_MAX)
#endif /* NGROUPS_MAX */
#else /* not _POSIX_VERSION */
uid_t getuid ();
gid_t getgid ();
uid_t geteuid ();
gid_t getegid ();
#include <sys/param.h>
#if !defined(NGROUPS_MAX) && defined(NGROUPS)
#define NGROUPS_MAX NGROUPS
#endif /* not NGROUPS_MAX and NGROUPS */
#endif /* not POSIX_VERSION */
#include <errno.h>
#ifndef errno
extern int errno;
#endif
#if defined(EACCES) && !defined(EACCESS)
#define EACCESS EACCES
#endif
#ifndef F_OK
#define F_OK 0
#define X_OK 1
#define W_OK 2
#define R_OK 4
#endif
#ifdef _LIBC
#define group_member __group_member
#else
/* The user's real user id. */
static uid_t uid;
/* The user's real group id. */
static gid_t gid;
/* The user's effective user id. */
static uid_t euid;
/* The user's effective group id. */
static gid_t egid;
/* Nonzero if UID, GID, EUID, and EGID have valid values. */
static int have_ids = 0;
#ifdef HAVE_GETGROUPS
int group_member ();
#else
#define group_member(gid) 0
#endif
#endif
/* Return 0 if the user has permission of type MODE on file PATH;
otherwise, return -1 and set `errno' to EACCESS.
Like access, except that it uses the effective user and group
id's instead of the real ones, and it does not check for read-only
filesystem, text busy, etc. */
int
euidaccess (path, mode)
const char *path;
int mode;
{
struct stat stats;
int granted;
#ifdef _LIBC
uid_t uid = getuid (), euid = geteuid ();
gid_t gid = getgid (), egid = getegid ();
#else
if (have_ids == 0)
{
have_ids = 1;
uid = getuid ();
gid = getgid ();
euid = geteuid ();
egid = getegid ();
}
#endif
if (uid == euid && gid == egid)
/* If we are not set-uid or set-gid, access does the same. */
return access (path, mode);
if (stat (path, &stats))
return -1;
mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */
#if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH
?error Oops, portability assumptions incorrect.
#endif
if (mode == F_OK)
return 0; /* The file exists. */
/* The super-user can read and write any file, and execute any file
that anyone can execute. */
if (euid == 0 && ((mode & X_OK) == 0
|| (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
return 0;
if (euid == stats.st_uid)
granted = (unsigned) (stats.st_mode & (mode << 6)) >> 6;
else if (egid == stats.st_gid || group_member (stats.st_gid))
granted = (unsigned) (stats.st_mode & (mode << 3)) >> 3;
else
granted = (stats.st_mode & mode);
if (granted == mode)
return 0;
errno = EACCESS;
return -1;
}
#ifdef TEST
#include <stdio.h>
#include <errno.h>
#include "error.h"
char *program_name;
int
main (argc, argv)
int argc;
char **argv;
{
char *file;
int mode;
int err;
program_name = argv[0];
if (argc < 3)
abort ();
file = argv[1];
mode = atoi (argv[2]);
err = euidaccess (file, mode);
printf ("%d\n", err);
if (err != 0)
error (0, errno, "%s", file);
exit (0);
}
#endif
|
