libld/common/support.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include    <stdio.h>
#include    <dlfcn.h>
#include    <libelf.h>
#include    <link.h>
#include    <debug.h>
#include    "msg.h"
#include    "_libld.h"

/*
 * Table which defines the default functions to be called by the library
 * SUPPORT (-S <libname>).  These functions can be redefined by the
 * ld_support_loadso() routine.
 */
static Support_list support[LDS_NUM] = {
    {MSG_ORIG(MSG_SUP_VERSION), NULL},  /* LDS_VERSION */
    {MSG_ORIG(MSG_SUP_INPUT_DONE),  NULL},  /* LDS_INPUT_DONE */
#if defined(_ELF64)
    {MSG_ORIG(MSG_SUP_START_64),    NULL},  /* LDS_START */
    {MSG_ORIG(MSG_SUP_ATEXIT_64),   NULL},  /* LDS_ATEXIT */
    {MSG_ORIG(MSG_SUP_OPEN_64), NULL},  /* LDS_OPEN */
    {MSG_ORIG(MSG_SUP_FILE_64), NULL},  /* LDS_FILE */
    {MSG_ORIG(MSG_SUP_INSEC_64),    NULL},  /* LDS_INSEC */
    {MSG_ORIG(MSG_SUP_SEC_64),  NULL}   /* LDS_SEC */
#else   /* Elf32 */
    {MSG_ORIG(MSG_SUP_START),   NULL},  /* LDS_START */
    {MSG_ORIG(MSG_SUP_ATEXIT),  NULL},  /* LDS_ATEXIT */
    {MSG_ORIG(MSG_SUP_OPEN),    NULL},  /* LDS_OPEN */
    {MSG_ORIG(MSG_SUP_FILE),    NULL},  /* LDS_FILE */
    {MSG_ORIG(MSG_SUP_INSEC),   NULL},  /* LDS_INSEC */
    {MSG_ORIG(MSG_SUP_SEC),     NULL}   /* LDS_SEC */
#endif
};

/*
 * Loads in a support shared object specified using the SGS_SUPPORT environment
 * variable or the -S ld option, and determines which interface functions are
 * provided by that object.
 */
uintptr_t
ld_sup_loadso(Ofl_desc *ofl, const char *obj)
{
    void    *handle, (*fptr)();
    uint_t  interface, version = LD_SUP_VERSION1;

    /*
     * Load the required support library.  If we are unable to load it fail
     * with a fatal error.
     */
    if ((handle = dlopen(obj, (RTLD_LAZY | RTLD_FIRST))) == NULL) {
        ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_SUP_NOLOAD),
            obj, dlerror());
        return (S_ERROR);
    }

    for (interface = 0; interface < LDS_NUM; interface++) {
        Func_list   fl;

        if ((fptr = (void (*)())dlsym(handle,
            support[interface].sup_name)) == NULL)
            continue;

        DBG_CALL(Dbg_support_load(ofl->ofl_lml, obj,
            support[interface].sup_name));

        if (interface == LDS_VERSION) {
            DBG_CALL(Dbg_support_action(ofl->ofl_lml, obj,
                support[LDS_VERSION].sup_name, LDS_VERSION, 0));

            version = ((uint_t(*)())fptr)(LD_SUP_VCURRENT);

            /*
             * If version is LD_SUP_VNONE, unload the support
             * library and act as if it was never requested.
             * This provides the support library with a mechanism
             * for opting out of the process.
             *
             * Note that this depends on LDS_VERSION being the
             * first item in support[]. If this were not true,
             * then other functions from the library might be
             * entered into the function lists, and unloading
             * the object would cause corruption.
             */
            assert(LDS_VERSION == 0);
            if (version == LD_SUP_VNONE) {
                DBG_CALL(Dbg_support_vnone(ofl->ofl_lml,
                    obj));
                (void) dlclose(handle);
                return (1);
            }

            /*
             * If the support library has a version higher
             * than we support, we are unable to accept it.
             */
            if (version > LD_SUP_VCURRENT) {
                ld_eprintf(ofl, ERR_FATAL,
                    MSG_INTL(MSG_SUP_BADVERSION), obj,
                    LD_SUP_VCURRENT, version);
                (void) dlclose(handle);
                return (S_ERROR);
            }
        }

        fl.fl_obj = obj;
        fl.fl_fptr = fptr;
        fl.fl_version = version;
        if (alist_append(&support[interface].sup_funcs, &fl,
            sizeof (Func_list), AL_CNT_SUPPORT) == NULL)
            return (S_ERROR);
    }
    return (1);
}

/*
 * Wrapper routines for the ld support library calls.
 */
void
ld_sup_start(Ofl_desc *ofl, const Half etype, const char *caller)
{
    Func_list   *flp;
    Aliste      idx;

    for (ALIST_TRAVERSE(support[LDS_START].sup_funcs, idx, flp)) {
        DBG_CALL(Dbg_support_action(ofl->ofl_lml, flp->fl_obj,
            support[LDS_START].sup_name, LDS_START, ofl->ofl_name));
        (*flp->fl_fptr)(ofl->ofl_name, etype, caller);
    }
}

void
ld_sup_atexit(Ofl_desc *ofl, int ecode)
{
    Func_list   *flp;
    Aliste      idx;

    for (ALIST_TRAVERSE(support[LDS_ATEXIT].sup_funcs, idx, flp)) {
        DBG_CALL(Dbg_support_action(ofl->ofl_lml, flp->fl_obj,
            support[LDS_ATEXIT].sup_name, LDS_ATEXIT, 0));
        (*flp->fl_fptr)(ecode);
    }
}

void
ld_sup_open(Ofl_desc *ofl, const char **opath, const char **ofile, int *ofd,
    int flags, Elf **oelf, Elf *ref, size_t off, const Elf_Kind ekind)
{
    Func_list   *flp;
    Aliste      idx;

    for (ALIST_TRAVERSE(support[LDS_OPEN].sup_funcs, idx, flp)) {
        const char  *npath = *opath;
        const char  *nfile = *ofile;
        Elf     *nelf = *oelf;
        int     nfd = *ofd;
        int     _flags = 0;

        /*
         * This interface was introduced in VERSION3.  Only call this
         * function for libraries reporting support for version 3 or
         * above.
         */
        if (flp->fl_version < LD_SUP_VERSION3)
            continue;

        if (!(flags & FLG_IF_CMDLINE))
            _flags |= LD_SUP_DERIVED;
        if (!(flags & FLG_IF_NEEDED))
            _flags |= LD_SUP_INHERITED;
        if (flags & FLG_IF_EXTRACT)
            _flags |= LD_SUP_EXTRACTED;

        /*
         * If the present object is an extracted archive member, make
         * sure the archive offset is reset so that the caller can
         * obtain an ELF descriptor to the same member (an elf_begin()
         * moves the offset to the next member).
         */
        if (flags & FLG_IF_EXTRACT)
            (void) elf_rand(ref, off);

        DBG_CALL(Dbg_support_action(ofl->ofl_lml, flp->fl_obj,
            support[LDS_OPEN].sup_name, LDS_OPEN, *opath));
        (*flp->fl_fptr)(&npath, &nfile, &nfd, _flags, &nelf, ref, off,
            ekind);

        /*
         * If the file descriptor, ELF descriptor, or file names have
         * been modified, then diagnose the differences and return the
         * new data.  As a basic test, make sure the support library
         * hasn't nulled out data ld(1) will try and dereference.
         */
        if ((npath != *opath) || (nfd != *ofd) || (nelf != *oelf)) {
            DBG_CALL(Dbg_file_modified(ofl->ofl_lml, flp->fl_obj,
                *opath, npath, *ofd, nfd, *oelf, nelf));
            if (npath)
                *opath = npath;
            if (nfile)
                *ofile = nfile;
            *ofd = nfd;
            *oelf = nelf;
        }
    }
}

void
ld_sup_file(Ofl_desc *ofl, const char *ifile, const Elf_Kind ekind, int flags,
    Elf *elf)
{
    Func_list   *flp;
    Aliste      idx;

    for (ALIST_TRAVERSE(support[LDS_FILE].sup_funcs, idx, flp)) {
        int _flags = 0;

        if (!(flags & FLG_IF_CMDLINE))
            _flags |= LD_SUP_DERIVED;
        if (!(flags & FLG_IF_NEEDED))
            _flags |= LD_SUP_INHERITED;
        if (flags & FLG_IF_EXTRACT)
            _flags |= LD_SUP_EXTRACTED;

        DBG_CALL(Dbg_support_action(ofl->ofl_lml, flp->fl_obj,
            support[LDS_FILE].sup_name, LDS_FILE, ifile));
        (*flp->fl_fptr)(ifile, ekind, _flags, elf);
    }
}

uintptr_t
ld_sup_input_section(Ofl_desc *ofl, Ifl_desc *ifl, const char *sname,
    Shdr **oshdr, Word ndx, Elf_Scn *scn, Elf *elf)
{
    Func_list   *flp;
    Aliste      idx;
    uint_t      flags = 0;
    Elf_Data    *data = NULL;

    for (ALIST_TRAVERSE(support[LDS_INSEC].sup_funcs, idx, flp)) {
        Shdr    *nshdr = *oshdr;

        /*
         * This interface was introduced in VERSION2.  Only call this
         * function for libraries reporting support for version 2 or
         * above.
         */
        if (flp->fl_version < LD_SUP_VERSION2)
            continue;

        if ((data == NULL) &&
            ((data = elf_getdata(scn, NULL)) == NULL)) {
            ld_eprintf(ofl, ERR_ELF, MSG_INTL(MSG_ELF_GETDATA),
                ifl->ifl_name);
            return (S_ERROR);
        }

        DBG_CALL(Dbg_support_action(ofl->ofl_lml, flp->fl_obj,
            support[LDS_INSEC].sup_name, LDS_INSEC, sname));
        (*flp->fl_fptr)(sname, &nshdr, ndx, data, elf, &flags);

        /*
         * If the section header has been re-allocated (known to occur
         * with libCCexcept.so), then diagnose the section header
         * difference and return the new section header.
         */
        if (nshdr != *oshdr) {
            Ehdr    *ehdr = ifl->ifl_ehdr;

            DBG_CALL(Dbg_shdr_modified(ofl->ofl_lml, flp->fl_obj,
                ehdr->e_ident[EI_OSABI], ehdr->e_machine, ndx,
                *oshdr, nshdr, sname));
            *oshdr = nshdr;
        }
    }
    return (0);
}

void
ld_sup_section(Ofl_desc *ofl, const char *scn, Shdr *shdr, Word ndx,
    Elf_Data *data, Elf *elf)
{
    Func_list   *flp;
    Aliste      idx;

    for (ALIST_TRAVERSE(support[LDS_SEC].sup_funcs, idx, flp)) {
        DBG_CALL(Dbg_support_action(ofl->ofl_lml, flp->fl_obj,
            support[LDS_SEC].sup_name, LDS_SEC, scn));
        (*flp->fl_fptr)(scn, shdr, ndx, data, elf);
    }
}

void
ld_sup_input_done(Ofl_desc *ofl)
{
    Func_list   *flp;
    Aliste      idx;
    uint_t      flags = 0;

    for (ALIST_TRAVERSE(support[LDS_INPUT_DONE].sup_funcs, idx, flp)) {
        /*
         * This interface was introduced in VERSION2.  Only call this
         * function for libraries reporting support for version 2 or
         * above.
         */
        if (flp->fl_version < LD_SUP_VERSION2)
            continue;

        DBG_CALL(Dbg_support_action(ofl->ofl_lml, flp->fl_obj,
            support[LDS_INPUT_DONE].sup_name, LDS_INPUT_DONE, 0));
        (*flp->fl_fptr)(&flags);
    }
}