| 1 | /* Test for access to file, relative to open directory. Linux version. |
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| 2 | Copyright (C) 2006-2024 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #include <fcntl.h> |
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| 20 | #include <unistd.h> |
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| 21 | #include <sys/types.h> |
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| 22 | #include <sys/stat.h> |
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| 23 | #include <sysdep.h> |
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| 24 | |
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| 25 | |
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| 26 | int |
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| 27 | __faccessat (int fd, const char *file, int mode, int flag) |
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| 28 | { |
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| 29 | int ret = INLINE_SYSCALL_CALL (faccessat2, fd, file, mode, flag); |
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| 30 | #if __ASSUME_FACCESSAT2 |
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| 31 | return ret; |
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| 32 | #else |
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| 33 | if (ret == 0 || errno != ENOSYS) |
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| 34 | return ret; |
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| 35 | |
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| 36 | if (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS)) |
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| 37 | return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL); |
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| 38 | |
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| 39 | if ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure))) |
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| 40 | return INLINE_SYSCALL (faccessat, 3, fd, file, mode); |
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| 41 | |
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| 42 | struct __stat64_t64 stats; |
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| 43 | if (__fstatat64_time64 (fd, file, &stats, flag & AT_SYMLINK_NOFOLLOW)) |
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| 44 | return -1; |
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| 45 | |
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| 46 | mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */ |
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| 47 | # if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH |
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| 48 | # error Oops, portability assumptions incorrect. |
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| 49 | # endif |
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| 50 | |
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| 51 | if (mode == F_OK) |
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| 52 | return 0; /* The file exists. */ |
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| 53 | |
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| 54 | uid_t uid = (flag & AT_EACCESS) ? __geteuid () : __getuid (); |
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| 55 | |
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| 56 | /* The super-user can read and write any file, and execute any file |
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| 57 | that anyone can execute. */ |
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| 58 | if (uid == 0 && ((mode & X_OK) == 0 |
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| 59 | || (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)))) |
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| 60 | return 0; |
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| 61 | |
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| 62 | int granted = (uid == stats.st_uid |
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| 63 | ? (unsigned int) (stats.st_mode & (mode << 6)) >> 6 |
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| 64 | : (stats.st_gid == ((flag & AT_EACCESS) |
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| 65 | ? __getegid () : __getgid ()) |
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| 66 | || __group_member (gid: stats.st_gid)) |
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| 67 | ? (unsigned int) (stats.st_mode & (mode << 3)) >> 3 |
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| 68 | : (stats.st_mode & mode)); |
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| 69 | |
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| 70 | if (granted == mode) |
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| 71 | return 0; |
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| 72 | |
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| 73 | return INLINE_SYSCALL_ERROR_RETURN_VALUE (EACCES); |
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| 74 | #endif /* !__ASSUME_FACCESSAT2 */ |
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| 75 | } |
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| 76 | weak_alias (__faccessat, faccessat) |
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| 77 | |
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