Merge commit 'b1e7e97d3b60469b243b3b2e22c7d8cbd11c7c90'

[unleashed.git] / usr / src / cmd / sgs / elfedit / common / elfedit_machelf.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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright 2018 OmniOS Community Edition (OmniOSce) Association.
 */

/*
 * ELFCLASS specific code for elfedit, built once for each class
 */
#include        <stdlib.h>
#include        <stdio.h>
#include        <unistd.h>
#include        <_machelf.h>
#include        <libelf.h>
#include        <strings.h>
#include        <sgs.h>
#include        "msg.h"
#include        "_elfedit.h"



/*
 * Look up the elfedit_symtab_t that corresponds to the symbol table
 * referenced by the sh_link field of the given auxiliary section.
 *
 * entry:
 *      obj_state - Partially constructed object state from
 *              elfedit_init_obj_state().
 *      auxsec - Section that is associated with the symbol table section
 *
 * exit:
 *      Returns the pointer to the elfedit_symtab_t entry that is
 *      referenced by the auxiliary section. If not found,
 *      outputs a debug message, and returns NULL.
 */
static elfedit_symtab_t *
get_symtab(elfedit_obj_state_t *obj_state, elfedit_section_t *auxsec)
{
        elfedit_symtab_t *symtab = obj_state->os_symtab;
        Word    sh_link = auxsec->sec_shdr->sh_link;
        Word    i;

        for (i = 0; i < obj_state->os_symtabnum; i++, symtab++)
                if (symtab->symt_shndx == sh_link)
                        return (symtab);

        /*
         * If we don't return above, it doesn't reference a valid
         * symbol table. Issue warning.
         */
        elfedit_msg(ELFEDIT_MSG_DEBUG, MSG_INTL(MSG_DEBUG_AUX_LINK),
            EC_WORD(auxsec->sec_shndx), auxsec->sec_name,
            EC_WORD(sh_link));

        return (NULL);
}


/*
 * Fill in state.elf.obj_state with a a dynamically allocated
 * elfedit_obj_state_t struct of the appropriate ELFCLASS.
 * This pre-chewed form is fed to each command, reducing the amount
 * of ELF boilerplate code each command needs to contain.
 *
 * entry:
 *      file - Name of file to process
 *      fd - Descriptor of open file which has been successfully
 *              processed by elf_begin().
 *      elf - Elf handle returned by elf_begin
 *
 * exit:
 *      An elfedit_obj_state_t struct of the appropriate ELFCLASS has
 *      been dynamically allocated, and state.elf.obj_state references it.
 *      On failure, this routine does not return to the caller.
 *
 * note: The resulting elfedit_obj_state_t is allocated from a single
 *      piece of memory, such that a single call to free() suffices
 *      to release it as well as any memory it references.
 */
#ifdef _ELF64
void
elfedit64_init_obj_state(const char *file, int fd, Elf *elf)
#else
void
elfedit32_init_obj_state(const char *file, int fd, Elf *elf)
#endif
{
#define INITIAL_SYMTABNDX_ALLOC 5

        /*
         * These macros are used to call functions from libelf.
         *
         * LIBELF_FAIL encapsulates the common way in which we handle
         * all of these errors: libelf_fail_name is set and execution
         * jumps to the libelf_failure label for handling.
         *
         * LIBELF is used for the common case in which the function returns
         * NULL for failure and something else for success.
         */
#define LIBELF_FAIL(_name) { libelf_fail_name = _name; goto libelf_failure; }
#define LIBELF(_libelf_expr, _name) \
        if ((_libelf_expr) == NULL) \
                LIBELF_FAIL(_name)

        const char *libelf_fail_name;   /* Used for LIBELF errors */

        Elf_Scn                 *scn;
        Elf_Data                *data;
        uint_t                  ndx;
        size_t                  len, os_size, secarr_size;
        char                    *names = 0;
        size_t                  names_len;
        elfedit_section_t       *_cache;
        elfedit_obj_state_t     tstate;
        elfedit_obj_state_t     *obj_state = NULL;
        Word                    *symtabndx = NULL;
        Word                    symtabndx_size = 0;
        elfedit_symtab_t        *symtab;

        tstate.os_file = file;
        tstate.os_fd = fd;
        tstate.os_elf = elf;
        tstate.os_dynndx = SHN_UNDEF;
        tstate.os_symtabnum = 0;

        LIBELF(tstate.os_ehdr = elf_getehdr(tstate.os_elf),
            MSG_ORIG(MSG_ELF_GETEHDR))

        /* Program header array count and address */
        if (elf_getphdrnum(tstate.os_elf, &tstate.os_phnum) == -1)
                LIBELF_FAIL(MSG_ORIG(MSG_ELF_GETPHDRNUM))
        if (tstate.os_phnum > 0) {
                LIBELF((tstate.os_phdr = elf_getphdr(tstate.os_elf)),
                    MSG_ORIG(MSG_ELF_GETPHDR))
        } else {
                tstate.os_phdr = NULL;
        }

        if (elf_getshdrnum(tstate.os_elf, &tstate.os_shnum) == -1)
                LIBELF_FAIL(MSG_ORIG(MSG_ELF_GETSHDRNUM))

        /*
         * Obtain the .shstrtab data buffer to provide the required section
         * name strings.
         */
        if (elf_getshdrstrndx(tstate.os_elf, &tstate.os_shstrndx) == -1)
                LIBELF_FAIL(MSG_ORIG(MSG_ELF_GETSHDRSTRNDX))
        LIBELF((scn = elf_getscn(tstate.os_elf, tstate.os_shstrndx)),
            MSG_ORIG(MSG_ELF_GETSCN))
        LIBELF((data = elf_getdata(scn, NULL)), MSG_ORIG(MSG_ELF_GETDATA))
        names = data->d_buf;
        names_len = (names == NULL) ? 0 : data->d_size;

        /*
         * Count the number of symbol tables and capture their indexes.
         * Find the dynamic section.
         */
        for (ndx = 1, scn = NULL; scn = elf_nextscn(tstate.os_elf, scn);
            ndx++) {
                Shdr *shdr;

                LIBELF(shdr = elf_getshdr(scn), MSG_ORIG(MSG_ELF_GETSHDR));

                switch (shdr->sh_type) {
                case SHT_DYNAMIC:
                        /* Save index of dynamic section for use below */
                        tstate.os_dynndx = ndx;
                        break;

                case SHT_SYMTAB:
                case SHT_DYNSYM:
                case SHT_SUNW_LDYNSYM:
                        if (symtabndx_size <= tstate.os_symtabnum) {
                                symtabndx_size = (symtabndx_size == 0) ?
                                    INITIAL_SYMTABNDX_ALLOC :
                                    (symtabndx_size * 2);
                                symtabndx = elfedit_realloc(
                                    MSG_INTL(MSG_ALLOC_SYMTABOS), symtabndx,
                                    symtabndx_size * sizeof (symtabndx[0]));
                        }
                        symtabndx[tstate.os_symtabnum++] = ndx;
                        break;
                }
        }

        /*
         * Allocate space to hold the state. We allocate space for everything
         * in one chunk to make releasing it easy:
         *      (1) elfedit_obj_state_t struct
         *      (2) The array of elfedit_section_t items referenced from
         *              the elfedit_obj_state_t struct.
         *      (3) The array of elfedit_symtab_t items referenced from
         *              the elfedit_obj_state_t struct.
         *      (4) The file name.
         *
         * Note that we round up the size of (1) and (2) to a double boundary
         * to ensure proper alignment of (2) and (3). (4) can align on any
         * boundary.
         */
        os_size = S_DROUND(sizeof (tstate));
        secarr_size = (tstate.os_shnum * sizeof (elfedit_section_t));
        secarr_size = S_DROUND(secarr_size);
        len = strlen(tstate.os_file) + 1;
        obj_state = elfedit_malloc(MSG_INTL(MSG_ALLOC_OBJSTATE),
            os_size + secarr_size +
            (tstate.os_symtabnum * sizeof (elfedit_symtab_t)) + len);
        *obj_state = tstate;

        /*LINTED E_BAD_PTR_CAST_ALIGN*/
        obj_state->os_secarr = (elfedit_section_t *)
            ((char *)obj_state + os_size);
        if (obj_state->os_symtabnum == 0) {
                obj_state->os_symtab = NULL;
        } else {
                /*LINTED E_BAD_PTR_CAST_ALIGN*/
                obj_state->os_symtab = (elfedit_symtab_t *)
                    ((char *)obj_state->os_secarr + secarr_size);
                obj_state->os_file =
                    (char *)(obj_state->os_symtab + tstate.os_symtabnum);
                (void) strncpy((char *)obj_state->os_file, tstate.os_file, len);
        }

        /*
         * Fill in obj_state->os_secarr with information for each section.
         * At the same time, fill in obj_state->os_symtab with the symbol
         * table related data.
         */
        bzero(obj_state->os_secarr, sizeof (obj_state->os_secarr[0]));
        _cache = obj_state->os_secarr;
        LIBELF(scn = elf_getscn(tstate.os_elf, 0),
            MSG_ORIG(MSG_ELF_GETSCN));
        _cache->sec_scn = scn;
        LIBELF(_cache->sec_shdr = elf_getshdr(scn), MSG_ORIG(MSG_ELF_GETSHDR));
        _cache->sec_name = (_cache->sec_shdr->sh_name < names_len) ?
            (names + _cache->sec_shdr->sh_name) : MSG_INTL(MSG_UNKNOWNSECNAM);
        _cache++;

        if (obj_state->os_symtab != NULL) {
                bzero(obj_state->os_symtab,
                    sizeof (obj_state->os_symtab[0]) * obj_state->os_symtabnum);
                for (ndx = 0; ndx < obj_state->os_symtabnum; ndx++)
                        obj_state->os_symtab[ndx].symt_shndx = symtabndx[ndx];
                free(symtabndx);
        }

        for (ndx = 1, scn = NULL; scn = elf_nextscn(tstate.os_elf, scn);
            ndx++, _cache++) {
                _cache->sec_shndx = ndx;
                _cache->sec_scn = scn;
                LIBELF(_cache->sec_shdr = elf_getshdr(scn),
                    MSG_ORIG(MSG_ELF_GETSHDR))
                _cache->sec_data = elf_getdata(scn, NULL);
                _cache->sec_name = (_cache->sec_shdr->sh_name < names_len) ?
                    (names + _cache->sec_shdr->sh_name) :
                    MSG_INTL(MSG_UNKNOWNSECNAM);

                switch (_cache->sec_shdr->sh_type) {
                case SHT_SYMTAB_SHNDX:
                        symtab = get_symtab(obj_state, _cache);
                        symtab->symt_xshndx = ndx;
                        break;

                case SHT_SUNW_syminfo:
                        symtab = get_symtab(obj_state, _cache);
                        symtab->symt_syminfo = ndx;
                        break;

                case SHT_SUNW_versym:
                        symtab = get_symtab(obj_state, _cache);
                        symtab->symt_versym = ndx;
                        break;
                }
        }

        /*
         * Sanity check the symbol tables, and discard any auxiliary
         * sections without enough elements.
         */
        symtab = obj_state->os_symtab;
        for (ndx = 0; ndx < obj_state->os_symtabnum; ndx++, symtab++) {
                elfedit_section_t       *symsec;
                Word                    symsec_cnt, aux_cnt;

                symsec = &obj_state->os_secarr[symtab->symt_shndx];
                symsec_cnt = symsec->sec_shdr->sh_size / sizeof (Sym);

                /* Extended section indexes */
                if (symtab->symt_xshndx != SHN_UNDEF) {
                        _cache = &obj_state->os_secarr[symtab->symt_xshndx];
                        aux_cnt = _cache->sec_shdr->sh_size / sizeof (Word);
                        if (symsec_cnt > aux_cnt)
                                elfedit_msg(ELFEDIT_MSG_DEBUG,
                                    MSG_INTL(MSG_DEBUG_AUX_SIZE),
                                    EC_WORD(ndx), _cache->sec_name,
                                    EC_WORD(aux_cnt),
                                    EC_WORD(symsec->sec_shndx),
                                    symsec->sec_name, EC_WORD(aux_cnt));
                }

                /* Syminfo */
                if (symtab->symt_syminfo != SHN_UNDEF) {
                        _cache = &obj_state->os_secarr[symtab->symt_syminfo];
                        aux_cnt = _cache->sec_shdr->sh_size / sizeof (Syminfo);
                        if (symsec_cnt > aux_cnt)
                                elfedit_msg(ELFEDIT_MSG_DEBUG,
                                    MSG_INTL(MSG_DEBUG_AUX_SIZE),
                                    EC_WORD(ndx), _cache->sec_name,
                                    EC_WORD(aux_cnt),
                                    EC_WORD(symsec->sec_shndx),
                                    symsec->sec_name, EC_WORD(aux_cnt));
                }

                /* Versym */
                if (symtab->symt_versym != SHN_UNDEF) {
                        _cache = &obj_state->os_secarr[symtab->symt_versym];
                        aux_cnt = _cache->sec_shdr->sh_size / sizeof (Versym);
                        if (symsec_cnt > aux_cnt)
                                elfedit_msg(ELFEDIT_MSG_DEBUG,
                                    MSG_INTL(MSG_DEBUG_AUX_SIZE),
                                    EC_WORD(ndx), _cache->sec_name,
                                    EC_WORD(aux_cnt),
                                    EC_WORD(symsec->sec_shndx),
                                    symsec->sec_name, EC_WORD(aux_cnt));
                }
        }

        /*
         * If this object has a dynsym section with a FLAGS_1 field,
         * then set the DF_1_EDITED bit. elfedit allows changes that
         * can break the resulting program, so knowing that a file was
         * edited can be helpful when encountering a core file or other
         * unexpected failure in the field. A single bit can't tell you
         * what was changed, but it will alert you to the possibility that
         * some additional questions might be in order.
         */
        if (obj_state->os_dynndx != SHN_UNDEF) {
                Word                    i;
                Word                    numdyn;
                elfedit_section_t       *dynsec;
                elfedit_dyn_elt_t       flags_1_elt;
                elfedit_dyn_elt_t       null_elt;
                Dyn                     *dyn;

                dynsec = &obj_state->os_secarr[obj_state->os_dynndx];
                dyn = (Dyn *) dynsec->sec_data->d_buf;
                numdyn = dynsec->sec_shdr->sh_size /
                    dynsec->sec_shdr->sh_entsize;
                elfedit_dyn_elt_init(&flags_1_elt);
                elfedit_dyn_elt_init(&null_elt);
                for (i = 0; i < numdyn; i++) {

                        switch (dyn[i].d_tag) {
                        case DT_NULL:
                                /*
                                 * Remember state of the first DT_NULL. If there
                                 * are more than one (i.e. the first one is not
                                 * in the final spot), and there is no flags1,
                                 * then we will turn the first one into a
                                 * DT_FLAGS_1.
                                 */
                                if (!null_elt.dn_seen)
                                        elfedit_dyn_elt_save(&null_elt, i,
                                            &dyn[i]);
                                break;

                        case DT_FLAGS_1:
                                elfedit_dyn_elt_save(&flags_1_elt, i, &dyn[i]);
                                break;
                        }
                }
                /* If don't have a flags1 field, can we make one from a NULL? */
                if (!flags_1_elt.dn_seen && null_elt.dn_seen &&
                    (null_elt.dn_ndx < (numdyn - 1))) {
                        elfedit_msg(ELFEDIT_MSG_DEBUG,
                            MSG_INTL(MSG_DEBUG_NULL2DYNFL1),
                            EC_WORD(obj_state->os_dynndx),
                            dynsec->sec_name, EC_WORD(null_elt.dn_ndx));
                        flags_1_elt.dn_seen = 1;
                        flags_1_elt.dn_ndx = null_elt.dn_ndx;
                        flags_1_elt.dn_dyn.d_tag = DT_FLAGS_1;
                        flags_1_elt.dn_dyn.d_un.d_val = 0;
                }
                /*
                 * If there is a flags 1 field, add the edit flag if
                 * it is not present, and report it's presence otherwise.
                 */
                if (flags_1_elt.dn_seen) {
                        if (flags_1_elt.dn_dyn.d_un.d_val & DF_1_EDITED) {
                                elfedit_msg(ELFEDIT_MSG_DEBUG,
                                    MSG_INTL(MSG_DEBUG_SEEDYNFLG),
                                    EC_WORD(obj_state->os_dynndx),
                                    dynsec->sec_name,
                                    EC_WORD(flags_1_elt.dn_ndx));
                        } else {
                                elfedit_msg(ELFEDIT_MSG_DEBUG,
                                    MSG_INTL(MSG_DEBUG_ADDDYNFLG),
                                    EC_WORD(obj_state->os_dynndx),
                                    dynsec->sec_name,
                                    EC_WORD(flags_1_elt.dn_ndx));
                                flags_1_elt.dn_dyn.d_un.d_val |= DF_1_EDITED;
                                dyn[flags_1_elt.dn_ndx] = flags_1_elt.dn_dyn;
                                elfedit_modified_data(dynsec);
                        }
                }
        }

#ifdef _ELF64
        state.elf.obj_state.s64 = obj_state;
#else
        state.elf.obj_state.s32 = obj_state;
#endif
        return;

libelf_failure:
        /*
         * Control comes here if there is an error with LIBELF.
         *
         * entry:
         *      libelf_fail_name - Name of failing libelf function
         *      tstate.os_file - Name of ELF file being processed
         *      tstate.os_fd - Descriptor of open ELF file
         *
         * exit:
         *      - dynamic memory is released if necessary
         *      - The error issued
         */
        free(obj_state);
        (void) close(tstate.os_fd);
        elfedit_elferr(tstate.os_file, libelf_fail_name);
#undef INITIAL_SYMTABNDX_ALLOC
#undef LIBELF_FAIL
#undef LIBELF
}