Fix some DLL hell: use dladdr() to find plugin dir

Normally one would dlopen() a shared object's basename, not its absolute
path.  However, lib/krb5/plugin.c, in an effort to be zero-conf-ish,
wants to readdir() to find plugins to load, and in the process it ends
up defeating the RTLD's search-the-caller's-rpath.

This commit partially addresses this by allowing the use of $ORIGIN in
plugin_dir values and using them for the default (except on OS X).

This allows multiple Heimdal versions installed on the same host, but
with different plugin ABIs, to co-exist.  A step forward for doing make
check on hosts where Heimdal is installed.

For now we hardcode $ORIGIN/../lib/plugin/krb5 (linux, Solaris, *BSD),
or $ORIGIN (Windows; for assemblies objects need to be in the same
directory) and we eval $ORIGIN by using dladdr() (Linux, Solaris) or
GetModuleHandleEx() (Win32, via a dladdr() wrapper in libroken) to find
the path to libkrb5 whose dirname to use as $ORIGIN.  For Windows,
because we need the plugins to be in the same directory as libkrb5, we
require a prefix on plugin DLLs ("plugin_krb5_") to distinguish them
from other objects.

We should add a special token to mean "look in $ORIGIN, sure, but
dlopen() the plugin basenames only (so the RTLD can search the rpath)".
This commit is contained in:
Nicolas Williams
2013-09-04 22:23:13 -05:00
parent 3e0fd6449e
commit 3e74e2e3bb
7 changed files with 110 additions and 4 deletions

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@@ -9,3 +9,11 @@ AC_DEFUN([rk_DLOPEN], [
#endif],[0,0])
AM_CONDITIONAL(HAVE_DLOPEN, test "$ac_cv_funclib_dlopen" != no)
])
AC_DEFUN([rk_DLADDR], [
AC_FIND_FUNC_NO_LIBS(dladdr, dl,[
#ifdef HAVE_DLFCN_H
#include <dlfcn.h>
#endif],[0,0])
AM_CONDITIONAL(HAVE_DLADDR, test "$ac_cv_funclib_dladdr" != no)
])

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@@ -500,6 +500,7 @@ AC_MSG_RESULT($ac_rk_have___sync_add_and_fetch)
AC_FUNC_MMAP
KRB_CAPABILITIES
rk_DLADDR
AC_CHECK_GETPWNAM_R_POSIX

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@@ -303,6 +303,10 @@ static const char *const rcsid[] = { (const char *)rcsid, "@(#)" msg }
/* MSVC doesn't provide a <dlfcn.h>, but we implement it in lib/roken. */
#define HAVE_DLOPEN 1
/* Define to 1 if you have the `dladdr' function. */
/* MSVC doesn't provide a <dlfcn.h>, but we implement it in lib/roken. */
#define HAVE_DLADDR 1
/* Define to 1 if you have the `dn_expand' function. */
/* #undef HAVE_DN_EXPAND */

View File

@@ -348,8 +348,12 @@ kt_ops_copy(krb5_context context, const krb5_context src_context)
}
static const char *sysplugin_dirs[] = {
LIBDIR "/plugin/krb5",
"$ORIGIN/../lib/plugin/krb5",
#ifdef _WIN32
"$ORIGIN/../lib",
#endif
#ifdef __APPLE__
LIBDIR "/plugin/krb5",
"/Library/KerberosPlugins/KerberosFrameworkPlugins",
"/System/Library/KerberosPlugins/KerberosFrameworkPlugins",
#endif
@@ -362,10 +366,14 @@ init_context_once(void *ctx)
krb5_context context = ctx;
char **dirs;
#ifdef _WIN32
dirs = rk_UNCONST(sysplugin_dirs);
#else
dirs = krb5_config_get_strings(context, NULL, "libdefaults",
"plugin_dir", NULL);
if (dirs == NULL)
dirs = rk_UNCONST(sysplugin_dirs);
#endif
_krb5_load_plugins(context, "krb5", (const char **)dirs);

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@@ -219,6 +219,38 @@ plug_dealloc(void *ptr)
dlclose(p->dsohandle);
}
static char *
resolve_origin(const char *di)
{
#ifdef HAVE_DLADDR
Dl_info dl_info;
const char *dname;
char *path, *p;
#endif
if (strncmp(di, "$ORIGIN/", sizeof("$ORIGIN/") - 1) &&
strcmp(di, "$ORIGIN"))
return strdup(di);
#ifndef HAVE_DLADDR
return strdup(LIBDIR "/plugin/krb5");
#else
di += sizeof("$ORIGIN") - 1;
if (dladdr(_krb5_load_plugins, &dl_info) == 0)
return strdup(LIBDIR "/plugin/krb5");
dname = dl_info.dli_fname;
p = strrchr(dname, '/');
if (p)
*p = '\0';
if (asprintf(&path, "%s%s", dname, di) == -1)
return NULL;
return path;
#endif
}
/**
* Load plugins (new system) for the given module @name (typicall
@@ -239,6 +271,7 @@ _krb5_load_plugins(krb5_context context, const char *name, const char **paths)
struct dirent *entry;
krb5_error_code ret;
const char **di;
char *dirname = NULL;
DIR *d;
HEIMDAL_MUTEX_lock(&plugin_mutex);
@@ -264,7 +297,11 @@ _krb5_load_plugins(krb5_context context, const char *name, const char **paths)
heim_release(s);
for (di = paths; *di != NULL; di++) {
d = opendir(*di);
free(dirname);
dirname = resolve_origin(*di);
if (dirname == NULL)
continue;
d = opendir(dirname);
if (d == NULL)
continue;
rk_cloexec_dir(d);
@@ -279,16 +316,21 @@ _krb5_load_plugins(krb5_context context, const char *name, const char **paths)
if (n[0] == '.' && (n[1] == '\0' || (n[1] == '.' && n[2] == '\0')))
continue;
#ifdef _WIN32
if (strncmp(n, "plugin_krb5_", sizeof("plugin_krb5_") - 1))
continue;
#endif
ret = 0;
#ifdef __APPLE__
{ /* support loading bundles on MacOS */
size_t len = strlen(n);
if (len > 7 && strcmp(&n[len - 7], ".bundle") == 0)
ret = asprintf(&path, "%s/%s/Contents/MacOS/%.*s", *di, n, (int)(len - 7), n);
ret = asprintf(&path, "%s/%s/Contents/MacOS/%.*s", dirname, n, (int)(len - 7), n);
}
#endif
if (ret < 0 || path == NULL)
ret = asprintf(&path, "%s/%s", *di, n);
ret = asprintf(&path, "%s/%s", dirname, n);
if (ret < 0 || path == NULL)
continue;
@@ -318,6 +360,7 @@ _krb5_load_plugins(krb5_context context, const char *name, const char **paths)
}
closedir(d);
}
free(dirname);
HEIMDAL_MUTEX_unlock(&plugin_mutex);
heim_release(module);
#endif /* HAVE_DLOPEN */

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@@ -32,6 +32,8 @@
#ifndef __dlfcn_h__
#define __dlfcn_h__
#include <windows.h>
#ifndef ROKEN_LIB_FUNCTION
#ifdef _WIN32
#define ROKEN_LIB_FUNCTION
@@ -75,6 +77,11 @@ dlopen(const char *, int);
ROKEN_LIB_FUNCTION DLSYM_RET_TYPE ROKEN_LIB_CALL
dlsym(void *, const char *);
typedef struct Dl_info {
char *dli_fname;
char _dli_buf[MAX_PATH + 2];
} Dl_info, Dl_info_t;
#ifdef __cplusplus
} /* extern "C" */
#endif

View File

@@ -163,3 +163,38 @@ dlsym(void * vhm, const char * func_name)
return (DLSYM_RET_TYPE)(ULONG_PTR)GetProcAddress(hm, func_name);
}
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
dladdr(void *addr, Dl_info *dli)
{
HMODULE hm;
int ret;
DWORD nsize;
char *p;
memset(dli, 0, sizeof(*dli));
if (!GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
(LPCTSTR)addr, &hm))
return -1;
nsize = GetModuleFileName(hm, dli->_dli_buf, sizeof(dli->_dli_buf));
dli->_dli_buf[sizeof(dli->_dli_buf) - 1] = '\0';
if (nsize >= sizeof(dli->_dli_buf))
return 0; /* truncated? can't be... */
/*
* Normalize path component separators, since our caller may want to
* portably take the dirname or basename of dli->dli_fname,
* searching for the last '/'.
*/
for (p = dli->_dli_buf;
p < &dli->_dli_buf[sizeof(dli->_dli_buf) - 1] && *p;
p++) {
if (*p == '\\')
*p = '/';
}
dli->dli_fname = dli->_dli_buf;
return 1;
}