/*      $NetBSD: map_object.c,v 1.71 2026/01/18 19:19:09 jmcneill Exp $  */

/*
 * Copyright 1996 John D. Polstra.
 * Copyright 1996 Matt Thomas <matt@3am-software.com>
 * Copyright 2002 Charles M. Hannum <root@ihack.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by John Polstra.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: map_object.c,v 1.71 2026/01/18 19:19:09 jmcneill Exp $");
#endif /* not lint */

#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>

#include "debug.h"
#include "rtld.h"

static int convert_prot(int);   /* Elf flags -> mmap protection */
static int convert_flags(int);  /* Elf flags -> mmap flags */

#define EA_UNDEF                (~(Elf_Addr)0)

/*
 * Map a shared object into memory.  The argument is a file descriptor,
 * which must be open on the object and positioned at its beginning.
 *
 * The return value is a pointer to a newly-allocated Obj_Entry structure
 * for the shared object.  Returns NULL on failure.
 */
Obj_Entry *
_rtld_map_object(const char *path, int fd, const struct stat *sb)
{
        Obj_Entry       *obj;
        Elf_Ehdr        *ehdr;
        Elf_Phdr        *phdr;
#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
        Elf_Phdr        *phtls;
#endif
        Elf_Phdr        *phlimit;
        Elf_Phdr       **segs = NULL;
        int              nsegs;
        caddr_t          mapbase = MAP_FAILED;
        size_t           mapsize = 0;
        int              mapflags;
        Elf_Addr         base_alignment;
        Elf_Addr         base_vaddr;
        Elf_Addr         base_vlimit;
        Elf_Addr         text_vlimit;
        Elf_Addr         text_end;
        void            *base_addr;
        Elf_Off          data_offset;
        Elf_Addr         data_vaddr;
        Elf_Addr         data_vlimit;
        int              data_flags;
        int              data_prot;
        caddr_t          data_addr;
        Elf_Addr         bss_vaddr;
        Elf_Addr         bss_vlimit;
        caddr_t          bss_addr;
#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
        Elf_Addr         tls_vaddr = 0; /* Noise GCC */
#endif
        Elf_Addr         phdr_vaddr;
        size_t           phdr_memsz, phsize;
        int i;
#ifdef RTLD_LOADER
        Elf_Addr         clear_vaddr;
        caddr_t          clear_page;
        caddr_t          clear_addr;
        size_t           nclear;
#endif
#ifdef GNU_RELRO
        Elf_Addr         relro_page;
        size_t           relro_size;
#endif
#ifdef notyet
        int              stack_flags;
#endif

        if (sb != NULL && sb->st_size < (off_t)sizeof (Elf_Ehdr)) {
                _rtld_error("%s: not ELF file (too short)", path);
                return NULL;
        }

        obj = _rtld_obj_new();
        obj->path = xstrdup(path);
        obj->pathlen = strlen(path);
        if (sb != NULL) {
                obj->dev = sb->st_dev;
                obj->ino = sb->st_ino;
        }

        ehdr = mmap(NULL, _rtld_pagesz, PROT_READ, MAP_FILE | MAP_SHARED, fd,
            (off_t)0);
        obj->ehdr = ehdr;
        if (ehdr == MAP_FAILED) {
                _rtld_error("%s: read error: %s", path, xstrerror(errno));
                goto error;
        }
        /* Make sure the file is valid */
        if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0) {
                _rtld_error("%s: not ELF file (magic number bad)", path);
                goto error;
        }
        if (ehdr->e_ident[EI_CLASS] != ELFCLASS) {
                _rtld_error("%s: invalid ELF class %x; expected %x", path,
                    ehdr->e_ident[EI_CLASS], ELFCLASS);
                goto error;
        }
        /* Elf_e_ident includes class */
        if (ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
            ehdr->e_version != EV_CURRENT ||
            ehdr->e_ident[EI_DATA] != ELFDEFNNAME(MACHDEP_ENDIANNESS)) {
                _rtld_error("%s: unsupported file version", path);
                goto error;
        }
        if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
                _rtld_error("%s: unsupported file type", path);
                goto error;
        }
        switch (ehdr->e_machine) {
                ELFDEFNNAME(MACHDEP_ID_CASES)
        default:
                _rtld_error("%s: unsupported machine", path);
                goto error;
        }

        /*
         * We rely on the program header being in the first page.  This is
         * not strictly required by the ABI specification, but it seems to
         * always true in practice.  And, it simplifies things considerably.
         */
        assert(ehdr->e_phentsize == sizeof(Elf_Phdr));
        assert(ehdr->e_phoff + ehdr->e_phnum * sizeof(Elf_Phdr) <=
            _rtld_pagesz);

        /*
         * Scan the program header entries, and save key information.
         *
         * We rely on there being exactly two load segments, text and data,
         * in that order.
         */
        phdr = (Elf_Phdr *) ((caddr_t)ehdr + ehdr->e_phoff);
#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
        phtls = NULL;
#endif
        phsize = ehdr->e_phnum * sizeof(phdr[0]);
        obj->phdr = NULL;
#ifdef GNU_RELRO
        relro_page = 0;
        relro_size = 0;
#endif
        phdr_vaddr = EA_UNDEF;
        phdr_memsz = 0;
        phlimit = phdr + ehdr->e_phnum;
        segs = xmalloc(sizeof(segs[0]) * ehdr->e_phnum);
        if (segs == NULL) {
                _rtld_error("No memory for segs");
                goto error;
        }
#ifdef notyet
        stack_flags = PF_R | PF_W;
#endif
        nsegs = -1;
        while (phdr < phlimit) {
                switch (phdr->p_type) {
                case PT_INTERP:
                        obj->interp = (void *)(uintptr_t)phdr->p_vaddr;
                        dbg(("%s: PT_INTERP %p", obj->path, obj->interp));
                        break;

                case PT_LOAD:
                        segs[++nsegs] = phdr;
                        if ((segs[nsegs]->p_align & (_rtld_pagesz - 1)) != 0) {
                                _rtld_error(
                                    "%s: PT_LOAD segment %d not page-aligned",
                                    path, nsegs);
                                goto error;
                        }
                        if ((segs[nsegs]->p_flags & PF_X) == PF_X) {
                                text_end = MAX(text_end,
                                    round_up(segs[nsegs]->p_vaddr +
                                    segs[nsegs]->p_memsz));
                        }

                        dbg(("%s: %s %p phsize %" PRImemsz, obj->path,
                            "PT_LOAD",
                            (void *)(uintptr_t)phdr->p_vaddr, phdr->p_memsz));
                        break;

                case PT_PHDR:
                        phdr_vaddr = phdr->p_vaddr;
                        phdr_memsz = phdr->p_memsz;
                        dbg(("%s: %s %p phsize %" PRImemsz, obj->path,
                            "PT_PHDR",
                            (void *)(uintptr_t)phdr->p_vaddr, phdr->p_memsz));
                        break;

#ifdef notyet
                case PT_GNU_STACK:
                        stack_flags = phdr->p_flags;
                        break;
#endif

#ifdef GNU_RELRO
                case PT_GNU_RELRO:
                        relro_page = phdr->p_vaddr;
                        relro_size = phdr->p_memsz;
                        break;
#endif

                case PT_DYNAMIC:
                        obj->dynamic = (void *)(uintptr_t)phdr->p_vaddr;
                        dbg(("%s: %s %p phsize %" PRImemsz, obj->path,
                            "PT_DYNAMIC",
                            (void *)(uintptr_t)phdr->p_vaddr, phdr->p_memsz));
                        break;

#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
                case PT_TLS:
                        phtls = phdr;
                        dbg(("%s: %s %p phsize %" PRImemsz, obj->path, "PT_TLS",
                            (void *)(uintptr_t)phdr->p_vaddr, phdr->p_memsz));
                        break;
#endif
#ifdef __ARM_EABI__
                case PT_ARM_EXIDX:
                        obj->exidx_start = (void *)(uintptr_t)phdr->p_vaddr;
                        obj->exidx_sz = phdr->p_memsz;
                        break;
#endif
                }

                ++phdr;
        }
        phdr = (Elf_Phdr *) ((caddr_t)ehdr + ehdr->e_phoff);
        obj->entry = (void *)(uintptr_t)ehdr->e_entry;
        if (!obj->dynamic) {
                _rtld_error("%s: not dynamically linked", path);
                goto error;
        }

        /*
         * Map the entire address space of the object as a file
         * region to stake out our contiguous region and establish a
         * base for relocation.  We use a file mapping so that
         * the kernel will give us whatever alignment is appropriate
         * for the platform we're running on.
         *
         * We map it using the text protection, map the data segment
         * into the right place, then map an anon segment for the bss
         * and unmap the gaps left by padding to alignment.
         */

        base_alignment = segs[0]->p_align;
        base_vaddr = round_down(segs[0]->p_vaddr);
        base_vlimit = round_up(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz);
        text_vlimit = round_up(segs[0]->p_vaddr + segs[0]->p_memsz);
        data_offset = round_down(segs[nsegs]->p_offset);
        data_vaddr = round_down(segs[nsegs]->p_vaddr);
        data_vlimit = round_up(segs[nsegs]->p_vaddr + segs[nsegs]->p_filesz);
        data_flags = convert_prot(segs[nsegs]->p_flags);
#ifdef RTLD_LOADER
        clear_vaddr = segs[nsegs]->p_vaddr + segs[nsegs]->p_filesz;
#endif

        obj->textsize = text_vlimit - base_vaddr;
        obj->vaddrbase = base_vaddr;
        obj->isdynamic = ehdr->e_type == ET_DYN;

#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
        if (phtls != NULL) {
                ++_rtld_tls_dtv_generation;
                obj->tlsindex = ++_rtld_tls_max_index;
                obj->tlssize = phtls->p_memsz;
                obj->tlsalign = phtls->p_align;
                obj->tlsinitsize = phtls->p_filesz;
                tls_vaddr = phtls->p_vaddr;
                dbg(("%s: tls index %zu size %zu align %zu initsize %zu",
                    obj->path, obj->tlsindex, obj->tlssize, obj->tlsalign,
                    obj->tlsinitsize));
        }
#endif

        /*
         * Calculate log2 of the base section alignment.
         */
        mapflags = MAP_PRIVATE | MAP_ANON;
        if (base_alignment > _rtld_pagesz) {
                unsigned int log2 = 0;
                for (; base_alignment > 1; base_alignment >>= 1)
                        log2++;
                mapflags |= MAP_ALIGNED(log2);
        }

        base_addr = NULL;
#ifdef RTLD_LOADER
        if (!obj->isdynamic) {
                mapflags |= MAP_TRYFIXED;
                base_addr = (void *)(uintptr_t)base_vaddr;
        }
#endif
        mapsize = base_vlimit - base_vaddr;
        mapbase = mmap(base_addr, mapsize, PROT_NONE, mapflags, -1, 0);
        if (mapbase == MAP_FAILED) {
                _rtld_error("mmap of entire address space failed: %s",
                    xstrerror(errno));
                goto error;
        }
#ifdef RTLD_LOADER
        if (!obj->isdynamic && mapbase != base_addr) {
                _rtld_error("mmap of executable at correct address failed");
                goto error;
        }
#endif

        obj->phdr_loaded = false;
        for (i = 0; i <= nsegs; i++) {
                /* Overlay the segment onto the proper region. */
                data_offset = round_down(segs[i]->p_offset);
                data_vaddr = round_down(segs[i]->p_vaddr);
                data_vlimit = round_up(segs[i]->p_vaddr
                    + segs[i]->p_filesz);
                data_addr = mapbase + (data_vaddr - base_vaddr);
                data_prot = convert_prot(segs[i]->p_flags);
                data_flags = convert_flags(segs[i]->p_flags) | MAP_FIXED;
                if (data_vlimit != data_vaddr &&
                    mmap(data_addr, data_vlimit - data_vaddr, data_prot,
                    data_flags, fd, data_offset) == MAP_FAILED) {
                        _rtld_error("%s: mmap of data failed: %s", path,
                            xstrerror(errno));
                        goto error;
                }

#ifdef RTLD_MAP_OBJECT_FIXUP
                if (_rtld_map_segment_fixup(path, fd, ehdr, segs[i], data_addr,
                                            data_vlimit - data_vaddr,
                                            data_prot) == -1) {
                        goto error;
                }
#endif
                /* Do BSS setup */
                if (segs[i]->p_filesz != segs[i]->p_memsz) {
#ifdef RTLD_LOADER
                        /* Clear any BSS in the last page of the segment. */
                        clear_vaddr = segs[i]->p_vaddr + segs[i]->p_filesz;
                        clear_addr = mapbase + (clear_vaddr - base_vaddr);
                        clear_page = mapbase + (round_down(clear_vaddr)
                            - base_vaddr);

                        if ((nclear = data_vlimit - clear_vaddr) > 0) {
                                /*
                                 * Make sure the end of the segment is
                                 * writable.
                                 */
                                if ((data_prot & PROT_WRITE) == 0 && -1 ==
                                     mprotect(clear_page, _rtld_pagesz,
                                     data_prot|PROT_WRITE)) {
                                        _rtld_error("%s: mprotect failed: %s",
                                            path, xstrerror(errno));
                                        goto error;
                                }

                                memset(clear_addr, 0, nclear);

                                /* Reset the data protection back */
                                if ((data_prot & PROT_WRITE) == 0)
                                        mprotect(clear_page, _rtld_pagesz,
                                            data_prot);
                        }
#endif

                        /* Overlay the BSS segment onto the proper region. */
                        bss_vaddr = data_vlimit;
                        bss_vlimit = round_up(segs[i]->p_vaddr +
                            segs[i]->p_memsz);
                        bss_addr = mapbase + (bss_vaddr - base_vaddr);
                        if (bss_vlimit > bss_vaddr) {
                                /* There is something to do */
                                if (mmap(bss_addr, bss_vlimit - bss_vaddr,
                                    data_prot, data_flags | MAP_ANON, -1, 0)
                                    == MAP_FAILED) {
                                        _rtld_error(
                                            "%s: mmap of bss failed: %s",
                                            path, xstrerror(errno));
                                        goto error;
                                }
                        }
                }

                if (phdr_vaddr != EA_UNDEF &&
                    segs[i]->p_vaddr <= phdr_vaddr &&
                    segs[i]->p_memsz >= phdr_memsz) {
                        obj->phdr_loaded = true;
                }
                if (segs[i]->p_offset <= ehdr->e_phoff &&
                    segs[i]->p_memsz >= phsize) {
                        phdr_vaddr = segs[i]->p_vaddr + ehdr->e_phoff;
                        phdr_memsz = phsize;
                        obj->phdr_loaded = true;
                }
        }
        if (obj->phdr_loaded) {
                obj->phdr = (void *)(uintptr_t)phdr_vaddr;
                obj->phsize = phdr_memsz;
        } else {
                Elf_Phdr *buf = xmalloc(phsize);
                if (buf == NULL) {
                        _rtld_error("%s: cannot allocate program header", path);
                        goto error;
                }
                memcpy(buf, phdr, phsize);
                obj->phdr = buf;
                obj->phsize = phsize;
        }

#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
        if (phtls != NULL) {
                obj->tlsinit = mapbase + tls_vaddr;
                dbg(("%s: tls init = %p + %"PRImemsz" = %p", obj->path,
                    mapbase, tls_vaddr, obj->tlsinit));
        }
#endif

        obj->mapbase = mapbase;
        obj->mapsize = mapsize;
        obj->relocbase = mapbase - base_vaddr;

#ifdef GNU_RELRO
        /* rounding happens later. */
        obj->relro_page = obj->relocbase + relro_page;
        obj->relro_size = relro_size;
#endif

        if (obj->dynamic)
                obj->dynamic = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->dynamic);
        if (obj->entry)
                obj->entry = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->entry);
        if (obj->interp)
                obj->interp = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->interp);
        if (obj->phdr_loaded)
                obj->phdr =  (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->phdr);
#ifdef __ARM_EABI__
        if (obj->exidx_start)
                obj->exidx_start = (void *)(obj->relocbase + (Elf_Addr)(uintptr_t)obj->exidx_start);
#endif
        xfree(segs);

        return obj;

error:
        if (mapbase != MAP_FAILED)
                munmap(mapbase, mapsize);
        if (obj->ehdr != MAP_FAILED)
                munmap(obj->ehdr, _rtld_pagesz);
        _rtld_obj_free(obj);
        xfree(segs);
        return NULL;
}

void
_rtld_obj_free(Obj_Entry *obj)
{
        Objlist_Entry *elm;
        Name_Entry *entry;

#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
        if (obj->tls_static)
                _rtld_tls_offset_free(obj);
#endif
        xfree(obj->path);
        while (obj->needed != NULL) {
                Needed_Entry *needed = obj->needed;
                obj->needed = needed->next;
                xfree(needed);
        }
        while ((entry = SIMPLEQ_FIRST(&obj->names)) != NULL) {
                SIMPLEQ_REMOVE_HEAD(&obj->names, link);
                xfree(entry);
        }
        while ((elm = SIMPLEQ_FIRST(&obj->dldags)) != NULL) {
                SIMPLEQ_REMOVE_HEAD(&obj->dldags, link);
                xfree(elm);
        }
        while ((elm = SIMPLEQ_FIRST(&obj->dagmembers)) != NULL) {
                SIMPLEQ_REMOVE_HEAD(&obj->dagmembers, link);
                xfree(elm);
        }
        if (!obj->phdr_loaded)
                xfree((void *)(uintptr_t)obj->phdr);
        xfree(obj);
}

Obj_Entry *
_rtld_obj_new(void)
{
        Obj_Entry *obj;

        obj = CNEW(Obj_Entry);
        SIMPLEQ_INIT(&obj->names);
        SIMPLEQ_INIT(&obj->dldags);
        SIMPLEQ_INIT(&obj->dagmembers);
        return obj;
}

/*
 * Given a set of ELF protection flags, return the corresponding protection
 * flags for MMAP.
 */
static int
convert_prot(int elfflags)
{
        int prot = 0;

        if (elfflags & PF_R)
                prot |= PROT_READ;
#ifdef RTLD_LOADER
        if (elfflags & PF_W)
                prot |= PROT_WRITE;
#endif
        if (elfflags & PF_X)
                prot |= PROT_EXEC;
        return prot;
}

static int
convert_flags(int elfflags __unused)
{
        int flags = MAP_PRIVATE; /* All mappings are private */

#ifdef MAP_NOCORE
        /*
         * Readonly mappings are marked "MAP_NOCORE", because they can be
         * reconstructed by a debugger.
         */
        if (!(elfflags & PF_W))
                flags |= MAP_NOCORE;
#endif
        return flags;
}