]>
Commit | Line | Data |
---|---|---|
d15b99ac | 1 | /* Test for access to file, relative to open directory. Linux version. |
d4697bc9 | 2 | Copyright (C) 2006-2014 Free Software Foundation, Inc. |
d15b99ac RM |
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 | |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
d15b99ac RM |
18 | |
19 | #include <errno.h> | |
20 | #include <fcntl.h> | |
21 | #include <stddef.h> | |
22 | #include <stdio.h> | |
23 | #include <string.h> | |
24 | #include <unistd.h> | |
25 | #include <sys/types.h> | |
26 | #include <alloca.h> | |
7c65e900 | 27 | #include <kernel-features.h> |
d15b99ac RM |
28 | #include <sysdep.h> |
29 | ||
7c65e900 | 30 | |
d15b99ac RM |
31 | int |
32 | faccessat (fd, file, mode, flag) | |
33 | int fd; | |
34 | const char *file; | |
35 | int mode; | |
36 | int flag; | |
37 | { | |
38 | if (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS)) | |
39 | { | |
40 | __set_errno (EINVAL); | |
41 | return -1; | |
42 | } | |
43 | ||
7c65e900 | 44 | #ifdef __NR_faccessat |
7a2645e4 | 45 | if ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure)) |
7c65e900 UD |
46 | # ifndef __ASSUME_ATFCTS |
47 | && __have_atfcts >= 0 | |
48 | # endif | |
49 | ) | |
d15b99ac | 50 | { |
c5453732 | 51 | int result = INLINE_SYSCALL (faccessat, 3, fd, file, mode); |
7c65e900 UD |
52 | # ifndef __ASSUME_ATFCTS |
53 | if (result == -1 && errno == ENOSYS) | |
54 | __have_atfcts = -1; | |
55 | else | |
56 | # endif | |
57 | return result; | |
d15b99ac | 58 | } |
7c65e900 | 59 | #endif |
d15b99ac | 60 | |
7c65e900 | 61 | #ifndef __ASSUME_ATFCTS |
d15b99ac | 62 | if ((!(flag & AT_EACCESS) || ! __libc_enable_secure) |
7c65e900 | 63 | # ifndef __NR_laccess /* Linux so far has no laccess syscall. */ |
d15b99ac | 64 | && !(flag & AT_SYMLINK_NOFOLLOW) |
7c65e900 | 65 | # endif |
d15b99ac RM |
66 | ) |
67 | { | |
68 | /* If we are not set-uid or set-gid, access does the same. */ | |
7c65e900 UD |
69 | char *buf = NULL; |
70 | ||
71 | if (fd != AT_FDCWD && file[0] != '/') | |
72 | { | |
73 | size_t filelen = strlen (file); | |
801720e6 UD |
74 | if (__builtin_expect (filelen == 0, 0)) |
75 | { | |
76 | __set_errno (ENOENT); | |
77 | return -1; | |
78 | } | |
79 | ||
7c65e900 UD |
80 | static const char procfd[] = "/proc/self/fd/%d/%s"; |
81 | /* Buffer for the path name we are going to use. It consists of | |
82 | - the string /proc/self/fd/ | |
83 | - the file descriptor number | |
84 | - the file name provided. | |
85 | The final NUL is included in the sizeof. A bit of overhead | |
86 | due to the format elements compensates for possible negative | |
87 | numbers. */ | |
88 | size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen; | |
89 | buf = alloca (buflen); | |
90 | ||
91 | __snprintf (buf, buflen, procfd, fd, file); | |
92 | file = buf; | |
93 | } | |
d15b99ac RM |
94 | |
95 | int result; | |
96 | INTERNAL_SYSCALL_DECL (err); | |
97 | ||
7c65e900 | 98 | # ifdef __NR_laccess |
d15b99ac RM |
99 | if (flag & AT_SYMLINK_NOFOLLOW) |
100 | result = INTERNAL_SYSCALL (laccess, err, 2, file, mode); | |
101 | else | |
7c65e900 | 102 | # endif |
d15b99ac RM |
103 | result = INTERNAL_SYSCALL (access, err, 2, file, mode); |
104 | ||
105 | if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0)) | |
106 | { | |
107 | __atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf); | |
108 | result = -1; | |
109 | } | |
110 | ||
111 | return result; | |
112 | } | |
7c65e900 | 113 | #endif |
d15b99ac RM |
114 | |
115 | struct stat64 stats; | |
3601428f | 116 | if (__fxstatat64 (_STAT_VER, fd, file, &stats, flag & AT_SYMLINK_NOFOLLOW)) |
d15b99ac RM |
117 | return -1; |
118 | ||
119 | mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */ | |
120 | #if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH | |
121 | # error Oops, portability assumptions incorrect. | |
122 | #endif | |
123 | ||
124 | if (mode == F_OK) | |
125 | return 0; /* The file exists. */ | |
126 | ||
127 | uid_t uid = (flag & AT_EACCESS) ? __geteuid () : __getuid (); | |
128 | ||
129 | /* The super-user can read and write any file, and execute any file | |
130 | that anyone can execute. */ | |
131 | if (uid == 0 && ((mode & X_OK) == 0 | |
132 | || (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)))) | |
133 | return 0; | |
134 | ||
135 | int granted = (uid == stats.st_uid | |
136 | ? (unsigned int) (stats.st_mode & (mode << 6)) >> 6 | |
137 | : (stats.st_gid == ((flag & AT_EACCESS) | |
138 | ? __getegid () : __getgid ()) | |
139 | || __group_member (stats.st_gid)) | |
140 | ? (unsigned int) (stats.st_mode & (mode << 3)) >> 3 | |
141 | : (stats.st_mode & mode)); | |
142 | ||
143 | if (granted == mode) | |
144 | return 0; | |
145 | ||
146 | __set_errno (EACCES); | |
147 | return -1; | |
148 | } |