676599b36a
This prevents injection of ':' and '\n' into output functions which use the NSS files database syntax. Critical fields (user/group names and file system paths) are checked strictly. For backwards compatibility, the GECOS field is rewritten instead. The getent program is adjusted to use the put*ent functions in libc, instead of local copies. This changes the behavior of getent if user names start with '-' or '+'.
77 lines
2.1 KiB
C
77 lines
2.1 KiB
C
/* Copyright (C) 1991-2015 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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#include <errno.h>
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#include <nss.h>
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#include <stdio.h>
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#include <string.h>
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#include <grp.h>
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#define flockfile(s) _IO_flockfile (s)
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#define funlockfile(s) _IO_funlockfile (s)
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#define _S(x) x ? x : ""
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/* Write an entry to the given stream.
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This must know the format of the group file. */
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int
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putgrent (const struct group *gr, FILE *stream)
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{
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int retval;
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if (__glibc_unlikely (gr == NULL) || __glibc_unlikely (stream == NULL)
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|| gr->gr_name == NULL || !__nss_valid_field (gr->gr_name)
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|| !__nss_valid_field (gr->gr_passwd)
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|| !__nss_valid_list_field (gr->gr_mem))
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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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flockfile (stream);
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if (gr->gr_name[0] == '+' || gr->gr_name[0] == '-')
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retval = fprintf (stream, "%s:%s::",
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gr->gr_name, _S (gr->gr_passwd));
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else
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retval = fprintf (stream, "%s:%s:%lu:",
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gr->gr_name, _S (gr->gr_passwd),
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(unsigned long int) gr->gr_gid);
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if (__builtin_expect (retval, 0) < 0)
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{
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funlockfile (stream);
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return -1;
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}
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if (gr->gr_mem != NULL)
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{
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for (size_t i = 0; gr->gr_mem[i] != NULL; i++)
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if (fprintf (stream, i == 0 ? "%s" : ",%s", gr->gr_mem[i]) < 0)
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{
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/* What else can we do? */
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funlockfile (stream);
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return -1;
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}
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}
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retval = fputc_unlocked ('\n', stream);
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funlockfile (stream);
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return retval < 0 ? -1 : 0;
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}
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