117 lines
3.0 KiB
C
117 lines
3.0 KiB
C
/*
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* SPDX-FileCopyrightText: 2007 - 2009, Nicolas François
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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/*
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* According to the Linux-PAM documentation:
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*
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* 4.1. Care about standard library calls
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*
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* In general, writers of authorization-granting applications should
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* assume that each module is likely to call any or all 'libc' functions.
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* For 'libc' functions that return pointers to static/dynamically
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* allocated structures (ie. the library allocates the memory and the
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* user is not expected to 'free()' it) any module call to this function
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* is likely to corrupt a pointer previously obtained by the application.
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* The application programmer should either re-call such a 'libc'
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* function after a call to the Linux-PAM library, or copy the structure
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* contents to some safe area of memory before passing control to the
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* Linux-PAM library.
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*
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* Two important function classes that fall into this category are
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* getpwnam(3) and syslog(3).
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*
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* This file provides wrapper to the name or name_r functions.
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*/
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <errno.h>
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#include "prototypes.h"
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#include "shadowlog.h"
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#define XFUNCTION_NAME XPREFIX (FUNCTION_NAME)
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#define XPREFIX(name) XPREFIX1 (name)
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#define XPREFIX1(name) x##name
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#define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
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#define APPEND_R(name) APPEND_R1 (name)
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#define APPEND_R1(name) name##_r
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#define STRINGIZE(name) STRINGIZE1 (name)
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#define STRINGIZE1(name) #name
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/*@null@*/ /*@only@*/LOOKUP_TYPE *XFUNCTION_NAME (ARG_TYPE ARG_NAME)
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{
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#if HAVE_FUNCTION_R
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LOOKUP_TYPE *result=NULL;
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char *buffer=NULL;
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/* we have to start with something */
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size_t length = 0x100;
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result = malloc(sizeof(LOOKUP_TYPE));
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if (NULL == result) {
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fprintf (log_get_logfd(), _("%s: out of memory\n"),
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"x" STRINGIZE(FUNCTION_NAME));
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exit (13);
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}
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while (true) {
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int status;
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LOOKUP_TYPE *resbuf = NULL;
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buffer = (char *)xreallocarray (buffer, length, sizeof(char));
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status = REENTRANT_NAME(ARG_NAME, result, buffer,
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length, &resbuf);
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if ((0 == status) && (resbuf == result)) {
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/* Build a result structure that can be freed by
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* the shadow *_free functions. */
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LOOKUP_TYPE *ret_result = DUP_FUNCTION(result);
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free(buffer);
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free(result);
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return ret_result;
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}
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if (ERANGE != status) {
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free (buffer);
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free (result);
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return NULL;
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}
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if (length <= ((size_t)-1 / 4)) {
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length *= 4;
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} else if (length == (size_t) -1) {
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break;
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} else {
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length = (size_t) -1;
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}
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}
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free(buffer);
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free(result);
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return NULL;
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#else /* !HAVE_FUNCTION_R */
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/* No reentrant function.
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* Duplicate the structure to avoid other call to overwrite it.
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*
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* We should also restore the initial structure. But that would be
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* overkill.
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*/
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LOOKUP_TYPE *result = FUNCTION_NAME(ARG_NAME);
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if (result) {
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result = DUP_FUNCTION(result);
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if (NULL == result) {
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fprintf (log_get_logfd(), _("%s: out of memory\n"),
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"x" STRINGIZE(FUNCTION_NAME));
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exit (13);
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}
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}
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return result;
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#endif
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}
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