pamdl.c

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#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
 
#ifdef USE_PAM_DLOPEN
/*
 * If you want to dynamically load libpam using dlopen() or something,
 * then dlopen( ' this shared object ' ); It takes care of exporting
 * the right symbols to any modules loaded by libpam.
 *
 * Modified by JY for use with openvpn-pam-auth
 */
 
#include <stdio.h>
#include <dlfcn.h>
#include <security/pam_appl.h>
 
#include "pamdl.h"
 
static void *libpam_h = NULL;
 
#define RESOLVE_PAM_FUNCTION(x, y, z, err)                                         \
    {                                                                              \
        union                                                                      \
        {                                                                          \
            const void *tpointer;                                                  \
            y(*fn) z;                                                              \
        } fptr;                                                                    \
        fptr.tpointer = dlsym(libpam_h, #x);                                       \
        real_##x = fptr.fn;                                                        \
        if (real_##x == NULL)                                                      \
        {                                                                          \
            fprintf(stderr, "PAMDL: unable to resolve '%s': %s\n", #x, dlerror()); \
            return err;                                                            \
        }                                                                          \
    }
 
int
dlopen_pam(const char *so)
{
    if (libpam_h == NULL)
    {
        libpam_h = dlopen(so, RTLD_GLOBAL | RTLD_NOW);
    }
    return libpam_h != NULL;
}
 
void
dlclose_pam(void)
{
    if (libpam_h != NULL)
    {
        dlclose(libpam_h);
        libpam_h = NULL;
    }
}
 
int
pam_start(const char *service_name, const char *user, const struct pam_conv *pam_conversation,
          pam_handle_t **pamh)
{
    int (*real_pam_start)(const char *, const char *, const struct pam_conv *, pam_handle_t **);
    RESOLVE_PAM_FUNCTION(pam_start, int,
                         (const char *, const char *, const struct pam_conv *, pam_handle_t **),
                         PAM_ABORT);
    return real_pam_start(service_name, user, pam_conversation, pamh);
}
 
int
pam_end(pam_handle_t *pamh, int pam_status)
{
    int (*real_pam_end)(pam_handle_t *, int);
    RESOLVE_PAM_FUNCTION(pam_end, int, (pam_handle_t *, int), PAM_ABORT);
    return real_pam_end(pamh, pam_status);
}
 
int
pam_set_item(pam_handle_t *pamh, int item_type, const void *item)
{
    int (*real_pam_set_item)(pam_handle_t *, int, const void *);
    RESOLVE_PAM_FUNCTION(pam_set_item, int, (pam_handle_t *, int, const void *), PAM_ABORT);
    return real_pam_set_item(pamh, item_type, item);
}
 
int
pam_get_item(const pam_handle_t *pamh, int item_type, const void **item)
{
    int (*real_pam_get_item)(const pam_handle_t *, int, const void **);
    RESOLVE_PAM_FUNCTION(pam_get_item, int, (const pam_handle_t *, int, const void **), PAM_ABORT);
    return real_pam_get_item(pamh, item_type, item);
}
 
int
pam_fail_delay(pam_handle_t *pamh, unsigned int musec_delay)
{
    int (*real_pam_fail_delay)(pam_handle_t *, unsigned int);
    RESOLVE_PAM_FUNCTION(pam_fail_delay, int, (pam_handle_t *, unsigned int), PAM_ABORT);
    return real_pam_fail_delay(pamh, musec_delay);
}
 
typedef const char *const_char_pointer;
 
const_char_pointer
pam_strerror(pam_handle_t *pamh, int errnum)
{
    const_char_pointer (*real_pam_strerror)(pam_handle_t *, int);
    RESOLVE_PAM_FUNCTION(pam_strerror, const_char_pointer, (pam_handle_t *, int), NULL);
    return real_pam_strerror(pamh, errnum);
}
 
int
pam_putenv(pam_handle_t *pamh, const char *name_value)
{
    int (*real_pam_putenv)(pam_handle_t *, const char *);
    RESOLVE_PAM_FUNCTION(pam_putenv, int, (pam_handle_t *, const char *), PAM_ABORT);
    return real_pam_putenv(pamh, name_value);
}
 
const_char_pointer
pam_getenv(pam_handle_t *pamh, const char *name)
{
    const_char_pointer (*real_pam_getenv)(pam_handle_t *, const char *);
    RESOLVE_PAM_FUNCTION(pam_getenv, const_char_pointer, (pam_handle_t *, const char *), NULL);
    return real_pam_getenv(pamh, name);
}
 
typedef char **char_ppointer;
char_ppointer
pam_getenvlist(pam_handle_t *pamh)
{
    char_ppointer (*real_pam_getenvlist)(pam_handle_t *);
    RESOLVE_PAM_FUNCTION(pam_getenvlist, char_ppointer, (pam_handle_t *), NULL);
    return real_pam_getenvlist(pamh);
}
 
/* Authentication management */
 
int
pam_authenticate(pam_handle_t *pamh, int flags)
{
    int (*real_pam_authenticate)(pam_handle_t *, int);
    RESOLVE_PAM_FUNCTION(pam_authenticate, int, (pam_handle_t *, int), PAM_ABORT);
    return real_pam_authenticate(pamh, flags);
}
 
int
pam_setcred(pam_handle_t *pamh, int flags)
{
    int (*real_pam_setcred)(pam_handle_t *, int);
    RESOLVE_PAM_FUNCTION(pam_setcred, int, (pam_handle_t *, int), PAM_ABORT);
    return real_pam_setcred(pamh, flags);
}
 
/* Account Management API's */
 
int
pam_acct_mgmt(pam_handle_t *pamh, int flags)
{
    int (*real_pam_acct_mgmt)(pam_handle_t *, int);
    RESOLVE_PAM_FUNCTION(pam_acct_mgmt, int, (pam_handle_t *, int), PAM_ABORT);
    return real_pam_acct_mgmt(pamh, flags);
}
 
/* Session Management API's */
 
int
pam_open_session(pam_handle_t *pamh, int flags)
{
    int (*real_pam_open_session)(pam_handle_t *, int);
    RESOLVE_PAM_FUNCTION(pam_open_session, int, (pam_handle_t *, int), PAM_ABORT);
    return real_pam_open_session(pamh, flags);
}
 
int
pam_close_session(pam_handle_t *pamh, int flags)
{
    int (*real_pam_close_session)(pam_handle_t *, int);
    RESOLVE_PAM_FUNCTION(pam_close_session, int, (pam_handle_t *, int), PAM_ABORT);
    return real_pam_close_session(pamh, flags);
}
 
/* Password Management API's */
 
int
pam_chauthtok(pam_handle_t *pamh, int flags)
{
    int (*real_pam_chauthtok)(pam_handle_t *, int);
    RESOLVE_PAM_FUNCTION(pam_chauthtok, int, (pam_handle_t *, int), PAM_ABORT);
    return real_pam_chauthtok(pamh, flags);
}
#endif /* ifdef USE_PAM_DLOPEN */