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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 '+'.
65 lines
2.0 KiB
C
65 lines
2.0 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 <stdio.h>
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#include <pwd.h>
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#include <nss.h>
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#define _S(x) x ?: ""
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/* Write an entry to the given stream. This must know the format of
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the password file. If the input contains invalid characters,
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return EINVAL, or replace them with spaces (if they are contained
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in the GECOS field). */
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int
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putpwent (const struct passwd *p, FILE *stream)
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{
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if (p == NULL || stream == NULL
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|| p->pw_name == NULL || !__nss_valid_field (p->pw_name)
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|| !__nss_valid_field (p->pw_passwd)
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|| !__nss_valid_field (p->pw_dir)
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|| !__nss_valid_field (p->pw_shell))
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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 ret;
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char *gecos_alloc;
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const char *gecos = __nss_rewrite_field (p->pw_gecos, &gecos_alloc);
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if (gecos == NULL)
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return -1;
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if (p->pw_name[0] == '+' || p->pw_name[0] == '-')
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ret = fprintf (stream, "%s:%s:::%s:%s:%s\n",
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p->pw_name, _S (p->pw_passwd),
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gecos, _S (p->pw_dir), _S (p->pw_shell));
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else
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ret = fprintf (stream, "%s:%s:%lu:%lu:%s:%s:%s\n",
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p->pw_name, _S (p->pw_passwd),
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(unsigned long int) p->pw_uid,
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(unsigned long int) p->pw_gid,
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gecos, _S (p->pw_dir), _S (p->pw_shell));
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free (gecos_alloc);
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if (ret >= 0)
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ret = 0;
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return ret;
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}
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