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https://github.com/linux-pam/linux-pam.git
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954234f0a4
The C standard guarantees that if the argument of free() is a null pointer, no action occurs.
126 lines
2.7 KiB
C
126 lines
2.7 KiB
C
/*
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* $Id$
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*
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* This function provides a thread safer version of getpwnam() for use
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* with PAM modules that care about this sort of thing.
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*
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* XXX - or at least it should provide a thread-safe alternative.
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*/
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#include "pam_modutil_private.h"
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#include <errno.h>
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#include <limits.h>
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#include <pwd.h>
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#include <stdio.h>
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#include <stdlib.h>
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static int intlen(int number)
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{
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int len = 2;
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while (number != 0) {
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number /= 10;
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len++;
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}
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return len;
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}
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struct passwd *
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pam_modutil_getpwnam(pam_handle_t *pamh, const char *user)
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{
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#ifdef HAVE_GETPWNAM_R
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void *buffer=NULL;
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size_t length = PWD_INITIAL_LENGTH;
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do {
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int status;
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void *new_buffer;
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struct passwd *result = NULL;
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new_buffer = realloc(buffer, sizeof(struct passwd) + length);
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if (new_buffer == NULL) {
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D(("out of memory"));
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/* no memory for the user - so delete the memory */
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free(buffer);
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return NULL;
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}
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buffer = new_buffer;
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/* make the re-entrant call to get the pwd structure */
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errno = 0;
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status = getpwnam_r(user, buffer,
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sizeof(struct passwd) + (char *) buffer,
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length, &result);
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if (!status && (result == buffer)) {
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char *data_name;
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const void *ignore;
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int i;
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data_name = malloc(strlen("_pammodutil_getpwnam") + 1 +
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strlen(user) + 1 + intlen(INT_MAX) + 1);
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if ((pamh != NULL) && (data_name == NULL)) {
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D(("was unable to register the data item [%s]",
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pam_strerror(pamh, status)));
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free(buffer);
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return NULL;
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}
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if (pamh != NULL) {
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for (i = 0; i < INT_MAX; i++) {
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sprintf(data_name, "_pammodutil_getpwnam_%s_%d", user, i);
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status = PAM_NO_MODULE_DATA;
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if (pam_get_data(pamh, data_name, &ignore) != PAM_SUCCESS) {
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status = pam_set_data(pamh, data_name,
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result, pam_modutil_cleanup);
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}
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if (status == PAM_SUCCESS) {
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break;
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}
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}
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} else {
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status = PAM_SUCCESS;
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}
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free(data_name);
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if (status == PAM_SUCCESS) {
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D(("success"));
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return result;
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}
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D(("was unable to register the data item [%s]",
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pam_strerror(pamh, status)));
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free(buffer);
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return NULL;
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} else if (errno != ERANGE && errno != EINTR) {
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/* no sense in repeating the call */
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break;
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}
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length <<= PWD_LENGTH_SHIFT;
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} while (length < PWD_ABSURD_PWD_LENGTH);
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D(("pwd structure took %zu bytes or so of memory",
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length+sizeof(struct passwd)));
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free(buffer);
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return NULL;
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#else /* ie. ifndef HAVE_GETPWNAM_R */
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/*
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* Sorry, there does not appear to be a reentrant version of
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* getpwnam(). So, we use the standard libc function.
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*/
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return getpwnam(user);
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#endif /* def HAVE_GETPWNAM_R */
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}
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