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146 lines
4.0 KiB
C
146 lines
4.0 KiB
C
/* Test for access to file, relative to open directory. Linux version.
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Copyright (C) 2006 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <fcntl.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <alloca.h>
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#include <kernel-features.h>
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#include <sysdep.h>
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int
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faccessat (fd, file, mode, flag)
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int fd;
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const char *file;
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int mode;
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int flag;
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{
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if (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS))
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{
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__set_errno (EINVAL);
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return -1;
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}
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int result;
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#ifdef __NR_faccessat
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if ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure))
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# ifndef __ASSUME_ATFCTS
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&& __have_atfcts >= 0
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# endif
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)
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{
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result = INLINE_SYSCALL (faccessat, 3, fd, file, mode);
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# ifndef __ASSUME_ATFCTS
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if (result == -1 && errno == ENOSYS)
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__have_atfcts = -1;
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else
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# endif
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return result;
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}
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#endif
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#ifndef __ASSUME_ATFCTS
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if ((!(flag & AT_EACCESS) || ! __libc_enable_secure)
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# ifndef __NR_laccess /* Linux so far has no laccess syscall. */
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&& !(flag & AT_SYMLINK_NOFOLLOW)
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# endif
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)
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{
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/* If we are not set-uid or set-gid, access does the same. */
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char *buf = NULL;
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if (fd != AT_FDCWD && file[0] != '/')
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{
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size_t filelen = strlen (file);
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static const char procfd[] = "/proc/self/fd/%d/%s";
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/* Buffer for the path name we are going to use. It consists of
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- the string /proc/self/fd/
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- the file descriptor number
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- the file name provided.
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The final NUL is included in the sizeof. A bit of overhead
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due to the format elements compensates for possible negative
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numbers. */
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size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
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buf = alloca (buflen);
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__snprintf (buf, buflen, procfd, fd, file);
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file = buf;
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}
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int result;
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INTERNAL_SYSCALL_DECL (err);
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# ifdef __NR_laccess
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if (flag & AT_SYMLINK_NOFOLLOW)
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result = INTERNAL_SYSCALL (laccess, err, 2, file, mode);
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else
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# endif
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result = INTERNAL_SYSCALL (access, err, 2, file, mode);
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if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
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{
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__atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
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result = -1;
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}
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return result;
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}
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#endif
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struct stat64 stats;
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if (fstatat64 (fd, file, &stats, flag & AT_SYMLINK_NOFOLLOW))
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return -1;
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mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */
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#if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH
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# error Oops, portability assumptions incorrect.
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#endif
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if (mode == F_OK)
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return 0; /* The file exists. */
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uid_t uid = (flag & AT_EACCESS) ? __geteuid () : __getuid ();
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/* The super-user can read and write any file, and execute any file
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that anyone can execute. */
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if (uid == 0 && ((mode & X_OK) == 0
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|| (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))))
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return 0;
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int granted = (uid == stats.st_uid
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? (unsigned int) (stats.st_mode & (mode << 6)) >> 6
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: (stats.st_gid == ((flag & AT_EACCESS)
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? __getegid () : __getgid ())
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|| __group_member (stats.st_gid))
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? (unsigned int) (stats.st_mode & (mode << 3)) >> 3
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: (stats.st_mode & mode));
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if (granted == mode)
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return 0;
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__set_errno (EACCES);
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return -1;
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}
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