kxld_sect.c   [plain text]

/*
 * Copyright (c) 2008 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
#include <string.h>
#include <mach-o/loader.h>
#include <mach-o/reloc.h>
#include <sys/types.h>

#define DEBUG_ASSERT_COMPONENT_NAME_STRING "kxld"
#include <AssertMacros.h>

#include "kxld_reloc.h"
#include "kxld_sect.h"
#include "kxld_seg.h"
#include "kxld_symtab.h"
#include "kxld_util.h"

static kern_return_t export_macho(const KXLDSect *sect, u_char *buf, u_long offset, 
    u_long bufsize);
#if KXLD_USER_OR_ILP32
static kern_return_t sect_export_macho_header_32(const KXLDSect *sect, u_char *buf, 
    u_long *header_offset, u_long header_size, u_long data_offset);
#endif
#if KXLD_USER_OR_LP64
static kern_return_t sect_export_macho_header_64(const KXLDSect *sect, u_char *buf, 
    u_long *header_offset, u_long header_size, u_long data_offset);
#endif

#if KXLD_USER_OR_ILP32
/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_sect_init_from_macho_32(KXLDSect *sect, u_char *macho, u_long *sect_offset,
    u_int sectnum, const KXLDRelocator *relocator)
{
    kern_return_t rval = KERN_FAILURE;
    struct section *src = (struct section *) ((void *) (macho + *sect_offset));
    struct relocation_info *relocs = NULL;

    check(sect);
    check(macho);
    check(src);

    strlcpy(sect->segname, src->segname, sizeof(sect->segname));
    strlcpy(sect->sectname, src->sectname, sizeof(sect->sectname));
    sect->base_addr = src->addr;
    sect->link_addr = src->addr;
    sect->size = src->size;
    sect->sectnum = sectnum;
    sect->flags = src->flags;
    sect->align = src->align;
    sect->reserved1 = src->reserved1;
    sect->reserved2 = src->reserved2;

    if (src->offset) {
        sect->data = macho + src->offset;
    } else {
        sect->data = NULL;
    }

    relocs = (struct relocation_info *) ((void *) (macho + src->reloff));

    rval = kxld_reloc_create_macho(&sect->relocs, relocator, 
        relocs, src->nreloc);
    require_noerr(rval, finish);

    *sect_offset += sizeof(*src);
    rval = KERN_SUCCESS;

finish:
    if (rval) kxld_sect_deinit(sect);

    return rval;
}
#endif /* KXLD_USER_OR_ILP32 */

#if KXLD_USER_OR_LP64
/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_sect_init_from_macho_64(KXLDSect *sect, u_char *macho, u_long *sect_offset,
    u_int sectnum, const KXLDRelocator *relocator)
{
    kern_return_t rval = KERN_FAILURE;
    struct section_64 *src = (struct section_64 *) ((void *) (macho + *sect_offset));
    struct relocation_info *relocs = NULL;

    check(sect);
    check(macho);
    check(src);

    strlcpy(sect->segname, src->segname, sizeof(sect->segname));
    strlcpy(sect->sectname, src->sectname, sizeof(sect->sectname));
    sect->base_addr = src->addr;
    sect->link_addr = src->addr;
    sect->size = src->size;
    sect->sectnum = sectnum;
    sect->flags = src->flags;
    sect->align = src->align;
    sect->reserved1 = src->reserved1;
    sect->reserved2 = src->reserved2;

    if (src->offset) {
        sect->data = macho + src->offset;
    } else {
        sect->data = NULL;
    }

    relocs = (struct relocation_info *) ((void *) (macho + src->reloff));

    rval = kxld_reloc_create_macho(&sect->relocs, relocator, 
        relocs, src->nreloc);
    require_noerr(rval, finish);

    *sect_offset += sizeof(*src);
    rval = KERN_SUCCESS;

finish:
    if (rval) kxld_sect_deinit(sect);

    return rval;
}
#endif /* KXLD_USER_OR_LP64 */

#if KXLD_USER_OR_GOT
/*******************************************************************************
* Assumes GOT is comprised of kxld_addr_t entries
*******************************************************************************/
kern_return_t
kxld_sect_init_got(KXLDSect *sect, u_int ngots)
{
    kern_return_t rval = KERN_FAILURE;

    check(sect);

    strlcpy(sect->segname, KXLD_SEG_GOT, sizeof(sect->segname));
    strlcpy(sect->sectname, KXLD_SECT_GOT, sizeof(sect->sectname));
    sect->base_addr = 0;
    sect->link_addr = 0;
    sect->flags = 0;
    sect->align = 4;
    sect->reserved1 = 0;
    sect->reserved2 = 0;

    sect->size = ngots * sizeof(kxld_addr_t);
    sect->data = kxld_alloc((u_long) sect->size);
    require_action(sect->data, finish, rval=KERN_RESOURCE_SHORTAGE);

    sect->allocated = TRUE;

    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_GOT */

#if KXLD_USER_OR_COMMON
/*******************************************************************************
*******************************************************************************/
void
kxld_sect_init_zerofill(KXLDSect *sect, const char *segname, 
    const char *sectname, kxld_size_t size, u_int align)
{
    check(sect);
    check(segname);
    check(sectname);

    strlcpy(sect->segname, segname, sizeof(sect->segname));
    strlcpy(sect->sectname, sectname, sizeof(sect->sectname));
    sect->size = size;
    sect->align = align;
    sect->base_addr = 0;
    sect->link_addr = 0;
    sect->flags = S_ZEROFILL;
}
#endif /* KXLD_USER_OR_COMMON */

/*******************************************************************************
*******************************************************************************/
void
kxld_sect_clear(KXLDSect *sect)
{
    check(sect);

    if (sect->allocated) {
        kxld_free(sect->data, (u_long) sect->size);
        sect->allocated = FALSE;
    }

    bzero(sect->sectname, sizeof(sect->sectname));
    bzero(sect->segname, sizeof(sect->segname));
    sect->data = NULL;
    sect->base_addr = 0;
    sect->link_addr = 0;
    sect->size = 0;
    sect->flags = 0;
    sect->align = 0;
    sect->reserved1 = 0;
    sect->reserved2 = 0;
    kxld_array_clear(&sect->relocs);
}

/*******************************************************************************
*******************************************************************************/
void
kxld_sect_deinit(KXLDSect *sect)
{
    check(sect);

    if (streq_safe(sect->sectname, KXLD_SECT_GOT, sizeof(KXLD_SECT_GOT))) {
        kxld_free(sect->data, (u_long) sect->size);
    }

    kxld_array_deinit(&sect->relocs);
    bzero(sect, sizeof(*sect));
}

/*******************************************************************************
*******************************************************************************/
u_int 
kxld_sect_get_num_relocs(const KXLDSect *sect)
{
    check(sect);

    return sect->relocs.nitems;
}

/*******************************************************************************
*******************************************************************************/
u_long
kxld_sect_get_macho_header_size(boolean_t is_32_bit)
{
    if (is_32_bit) {
        return sizeof(struct section);
    } else {
        return sizeof(struct section_64);
    }
}

/*******************************************************************************
*******************************************************************************/
u_long
kxld_sect_get_macho_data_size(const KXLDSect *sect)
{
    u_long size = 0;

    check(sect);

    if (sect->data) {
        size = (u_long) sect->size;
    }

    return size;
}

#if KXLD_USER_OR_GOT
/*******************************************************************************
*******************************************************************************/
u_int
kxld_sect_get_ngots(const KXLDSect *sect, const KXLDRelocator *relocator,
    const KXLDSymtab *symtab)
{
    const KXLDReloc *reloc = NULL;
    KXLDSym *sym = NULL;
    u_int ngots = 0;
    u_int i = 0;
    
    for (i = 0; i < sect->relocs.nitems; ++i) {
        reloc = kxld_array_get_item(&sect->relocs, i);

        if (relocator->reloc_has_got(reloc->reloc_type)) {
            /* @TODO This assumes 64-bit symbols (which is valid at the
             * moment since only x86_64 has a GOT)
             */
            sym = kxld_reloc_get_symbol(relocator, reloc, sect->data, symtab);
            if (!kxld_sym_is_got(sym)) {
                kxld_sym_set_got(sym);
                ++ngots;
            }
        }
    }

    return ngots;
}
#endif /* KXLD_USER_OR_GOT */

/*******************************************************************************
* Each section must be aligned at a certain power of two.  To figure out that 
* alignment, we mask for the low bits that may need to be adjusted.  If they are 
* non zero, we then subtract them from the target alignment to find the offset, 
* and then add that offset to the link address.
*******************************************************************************/
kxld_addr_t
kxld_sect_align_address(const KXLDSect *sect, kxld_addr_t address)
{
    return kxld_align_address(address, sect->align);
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_sect_export_macho_to_file_buffer(const KXLDSect *sect, u_char *buf,
    u_long *header_offset, u_long header_size, u_long *data_offset, 
    u_long data_size, boolean_t is_32_bit __unused)
{
    kern_return_t rval = KERN_FAILURE;

    check(sect);
    check(buf);
    check(header_offset);
    check(data_offset);

    /* If there is no data to export, we only need to write the header.  We
     * make it a separate call so that we don't modify data_offset.
     */
    if (!sect->data) {
        KXLD_3264_FUNC(is_32_bit, rval,
            sect_export_macho_header_32, sect_export_macho_header_64,
            sect, buf, header_offset, header_size, /* data_offset */ 0);
        require_noerr(rval, finish);
    } else {
        *data_offset = (u_long) kxld_sect_align_address(sect, *data_offset);

        KXLD_3264_FUNC(is_32_bit, rval,
            sect_export_macho_header_32, sect_export_macho_header_64,
            sect, buf, header_offset, header_size, *data_offset);
        require_noerr(rval, finish);

        rval = export_macho(sect, buf, *data_offset, data_size);
        require_noerr(rval, finish);

        *data_offset += (u_long) sect->size;
    }
        
    rval = KERN_SUCCESS;

finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_sect_export_macho_to_vm(const KXLDSect *sect, u_char *buf, 
    u_long *header_offset, u_long header_size, 
    kxld_addr_t link_addr, u_long data_size, 
    boolean_t is_32_bit __unused)
{
    kern_return_t rval = KERN_FAILURE;
    u_long data_offset = (u_long) (sect->link_addr - link_addr);

    check(sect);
    check(buf);
    check(header_offset);

    KXLD_3264_FUNC(is_32_bit, rval,
        sect_export_macho_header_32, sect_export_macho_header_64,
        sect, buf, header_offset, header_size, data_offset);
    require_noerr(rval, finish);

    rval = export_macho(sect, buf, data_offset, data_size);
    require_noerr(rval, finish);

    rval = KERN_SUCCESS;

finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
export_macho(const KXLDSect *sect, u_char *buf, u_long offset, u_long bufsize)
{
    kern_return_t rval = KERN_FAILURE;

    check(sect);
    check(buf);

    if (!sect->data) {
        rval = KERN_SUCCESS;
        goto finish;
    }

    /* Verify that the section is properly aligned */

    require_action(kxld_sect_align_address(sect, offset) == offset, finish,
        rval = KERN_FAILURE);

    /* Verify that we have enough space to copy */

    require_action(sect->size <= bufsize - offset, finish,
        rval=KERN_FAILURE);

    /* Copy section data */

    switch (sect->flags & SECTION_TYPE) {
    case S_NON_LAZY_SYMBOL_POINTERS:
    case S_MOD_INIT_FUNC_POINTERS:
    case S_MOD_TERM_FUNC_POINTERS:
    case S_REGULAR:
    case S_CSTRING_LITERALS:
    case S_4BYTE_LITERALS:
    case S_8BYTE_LITERALS:
    case S_LITERAL_POINTERS:
    case S_COALESCED:
    case S_16BYTE_LITERALS:
    case S_SYMBOL_STUBS:
        memcpy(buf + offset, sect->data, (size_t)sect->size);
        break;
    case S_ZEROFILL: /* sect->data should be NULL, so we'll never get here */
    case S_LAZY_SYMBOL_POINTERS:
    case S_GB_ZEROFILL:
    case S_INTERPOSING:
    case S_DTRACE_DOF:
    default:
        rval = KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
            "Invalid section type: %u.", sect->flags & SECTION_TYPE);
        goto finish;
    }

    rval = KERN_SUCCESS;

finish:
    return rval;
}

#if KXLD_USER_OR_ILP32
/*******************************************************************************
*******************************************************************************/
static kern_return_t
sect_export_macho_header_32(const KXLDSect *sect, u_char *buf, 
    u_long *header_offset, u_long header_size, u_long data_offset)
{
    kern_return_t rval = KERN_FAILURE;
    struct section *secthdr = NULL;

    check(sect);
    check(buf);
    check(header_offset);
    
    require_action(sizeof(*secthdr) <= header_size - *header_offset, finish,
        rval=KERN_FAILURE);
    secthdr = (struct section *) ((void *) (buf + *header_offset));
    *header_offset += sizeof(*secthdr);

    /* Initalize header */

    strlcpy(secthdr->sectname, sect->sectname, sizeof(secthdr->sectname));
    strlcpy(secthdr->segname, sect->segname, sizeof(secthdr->segname));
    secthdr->addr = (uint32_t) sect->link_addr;
    secthdr->size = (uint32_t) sect->size;
    secthdr->offset = (uint32_t) ((sect->data) ? data_offset : 0);
    secthdr->align = sect->align;
    secthdr->reloff = 0;
    secthdr->nreloc = 0;
    secthdr->flags = sect->flags;
    secthdr->reserved1 = sect->reserved1;
    secthdr->reserved2 = sect->reserved2;

    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_ILP32 */

#if KXLD_USER_OR_LP64
/*******************************************************************************
*******************************************************************************/
static kern_return_t
sect_export_macho_header_64(const KXLDSect *sect, u_char *buf, 
    u_long *header_offset, u_long header_size, u_long data_offset)
{
    kern_return_t rval = KERN_FAILURE;
    struct section_64 *secthdr = NULL;

    check(sect);
    check(buf);
    check(header_offset);
    
    require_action(sizeof(*secthdr) <= header_size - *header_offset, finish,
        rval=KERN_FAILURE);
    secthdr = (struct section_64 *) ((void *) (buf + *header_offset));
    *header_offset += sizeof(*secthdr);

    /* Initalize header */

    strlcpy(secthdr->sectname, sect->sectname, sizeof(secthdr->sectname));
    strlcpy(secthdr->segname, sect->segname, sizeof(secthdr->segname));
    secthdr->addr = (uint64_t) sect->link_addr;
    secthdr->size = (uint64_t) sect->size;
    secthdr->offset = (uint32_t) ((sect->data) ? data_offset : 0);
    secthdr->align = sect->align;
    secthdr->reloff = 0;
    secthdr->nreloc = 0;
    secthdr->flags = sect->flags;
    secthdr->reserved1 = sect->reserved1;
    secthdr->reserved2 = sect->reserved2;

    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_LP64 */

#if KXLD_USER_OR_COMMON
/*******************************************************************************
*******************************************************************************/
kxld_size_t
kxld_sect_grow(KXLDSect *sect, kxld_size_t nbytes, u_int align)
{
    kxld_size_t size = kxld_align_address(sect->size, align);

    if (align > sect->align) sect->align = align;
    sect->size = size + nbytes;

    return size;
}
#endif /* KXLD_USER_OR_COMMON */

/*******************************************************************************
*******************************************************************************/
void
kxld_sect_relocate(KXLDSect *sect, kxld_addr_t link_addr)
{
    sect->link_addr = kxld_sect_align_address(sect, 
        sect->link_addr + link_addr);
}

#if KXLD_USER_OR_GOT
/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_sect_populate_got(KXLDSect *sect, KXLDSymtab *symtab, 
    boolean_t swap __unused)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSymtabIterator iter;
    KXLDSym *sym = NULL;
    kxld_addr_t *entry = NULL;
    kxld_addr_t entry_addr = 0;

    check(sect);
    check(symtab);
    require(streq_safe(sect->segname, KXLD_SEG_GOT, sizeof(KXLD_SEG_GOT)), 
        finish);
    require(streq_safe(sect->sectname, KXLD_SECT_GOT, sizeof(KXLD_SECT_GOT)), 
        finish);

    kxld_symtab_iterator_init(&iter, symtab, kxld_sym_is_got, FALSE);
    
    entry = (kxld_addr_t *) sect->data;
    entry_addr = sect->link_addr;
    while ((sym = kxld_symtab_iterator_get_next(&iter))) {
        *entry = sym->link_addr;
        sym->got_addr = entry_addr;

#if !KERNEL
        if (swap) *entry = OSSwapInt64(*entry);
#endif /* !KERNEL */

        ++entry;
        entry_addr += sizeof(*entry);
    }

    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_GOT */

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_sect_process_relocs(KXLDSect *sect, KXLDRelocator *relocator)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDReloc *reloc = NULL;
    u_int i = 0;

    for (i = 0; i < sect->relocs.nitems; ++i) {
        reloc = kxld_array_get_item(&sect->relocs, i);
        rval = kxld_relocator_process_sect_reloc(relocator, reloc, sect);
        require_noerr(rval, finish);
    }

    rval = KERN_SUCCESS;
finish:
    return rval;
}