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04277e02d7
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216 lines
4.7 KiB
C
216 lines
4.7 KiB
C
/* Check if effective user id can access file
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Copyright (C) 1990-2019 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, see
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<http://www.gnu.org/licenses/>. */
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/* Written by David MacKenzie and Torbjorn Granlund.
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Adapted for GNU C library by Roland McGrath. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <sys/types.h>
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#include <sys/stat.h>
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#ifdef S_IEXEC
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# ifndef S_IXUSR
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# define S_IXUSR S_IEXEC
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# endif
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# ifndef S_IXGRP
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# define S_IXGRP (S_IEXEC >> 3)
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# endif
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# ifndef S_IXOTH
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# define S_IXOTH (S_IEXEC >> 6)
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# endif
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#endif /* S_IEXEC */
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#if defined HAVE_UNISTD_H || defined _LIBC
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# include <unistd.h>
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#endif
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#ifndef _POSIX_VERSION
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uid_t getuid ();
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gid_t getgid ();
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uid_t geteuid ();
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gid_t getegid ();
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#endif /* not POSIX_VERSION */
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#include <errno.h>
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#ifndef errno
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extern int errno;
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#endif
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#ifndef __set_errno
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# define __set_errno(val) errno = (val)
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#endif
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#if defined EACCES && !defined EACCESS
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# define EACCESS EACCES
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#endif
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#ifndef F_OK
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# define F_OK 0
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# define X_OK 1
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# define W_OK 2
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# define R_OK 4
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#endif
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#if !defined S_IROTH && defined R_OK
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# define S_IROTH R_OK
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#endif
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#if !defined S_IWOTH && defined W_OK
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# define S_IWOTH W_OK
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#endif
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#if !defined S_IXOTH && defined X_OK
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# define S_IXOTH X_OK
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#endif
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#ifdef _LIBC
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# define group_member __group_member
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# define euidaccess __euidaccess
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#else
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/* The user's real user id. */
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static uid_t uid;
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/* The user's real group id. */
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static gid_t gid;
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/* The user's effective user id. */
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static uid_t euid;
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/* The user's effective group id. */
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static gid_t egid;
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/* Nonzero if UID, GID, EUID, and EGID have valid values. */
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static int have_ids;
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# ifdef HAVE_GETGROUPS
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int group_member ();
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# else
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# define group_member(gid) 0
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# endif
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#endif
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/* Return 0 if the user has permission of type MODE on file PATH;
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otherwise, return -1 and set `errno' to EACCESS.
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Like access, except that it uses the effective user and group
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id's instead of the real ones, and it does not check for read-only
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filesystem, text busy, etc. */
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int
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euidaccess (const char *path, int mode)
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{
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struct stat64 stats;
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int granted;
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#ifdef _LIBC
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uid_t euid;
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gid_t egid;
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#else
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if (have_ids == 0)
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{
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have_ids = 1;
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uid = getuid ();
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gid = getgid ();
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euid = geteuid ();
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egid = getegid ();
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}
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if (uid == euid && gid == egid)
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/* If we are not set-uid or set-gid, access does the same. */
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return access (path, mode);
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#endif
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if (stat64 (path, &stats))
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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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#ifdef _LIBC
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/* Now we need the IDs. */
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euid = __geteuid ();
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egid = __getegid ();
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if (__getuid () == euid && __getgid () == egid)
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/* If we are not set-uid or set-gid, access does the same. */
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return __access (path, mode);
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#endif
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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 (euid == 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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if (euid == stats.st_uid)
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granted = (unsigned int) (stats.st_mode & (mode << 6)) >> 6;
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else if (egid == stats.st_gid || group_member (stats.st_gid))
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granted = (unsigned int) (stats.st_mode & (mode << 3)) >> 3;
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else
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granted = (stats.st_mode & mode);
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/* XXX Add support for ACLs. */
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if (granted == mode)
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return 0;
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__set_errno (EACCESS);
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return -1;
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}
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#undef euidaccess
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#undef eaccess
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#ifdef weak_alias
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weak_alias (__euidaccess, euidaccess)
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weak_alias (__euidaccess, eaccess)
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#endif
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#ifdef TEST
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# include <stdio.h>
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# include <errno.h>
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# include "error.h"
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char *program_name;
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int
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main (int argc, char **argv)
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{
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char *file;
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int mode;
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int err;
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program_name = argv[0];
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if (argc < 3)
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abort ();
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file = argv[1];
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mode = atoi (argv[2]);
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err = euidaccess (file, mode);
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printf ("%d\n", err);
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if (err != 0)
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error (0, errno, "%s", file);
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exit (0);
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}
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#endif
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