text: /*-
   * Copyright 1996-1998 John D. Polstra.
   * 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.
   *
   * 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.
   *
   * $FreeBSD$
   */
  
  #include <sys/param.h>
  #include <sys/mman.h>
  #include <sys/stat.h>
  
  #include <errno.h>
  #include <stddef.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "debug.h"
  #include "rtld.h"
  
  static Elf_Ehdr *get_elf_header(int, const char *);
  static int convert_flags(int); /* Elf flags -> mmap flags */
  
  /*
   * Map a shared object into memory.  The "fd" argument is a file descriptor,
   * which must be open on the object and positioned at its beginning.
   * The "path" argument is a pathname that is used only for error messages.
   *
   * The return value is a pointer to a newly-allocated Obj_Entry structure
   * for the shared object.  Returns NULL on failure.
   */
  Obj_Entry *
  map_object(int fd, const char *path, const struct stat *sb)
  {
      Obj_Entry *obj;
      Elf_Ehdr *hdr;
      int i;
      Elf_Phdr *phdr;
      Elf_Phdr *phlimit;
      Elf_Phdr **segs;
      int nsegs;
      Elf_Phdr *phdyn;
      Elf_Phdr *phinterp;
      Elf_Phdr *phtls;
      caddr_t mapbase;
      caddr_t shlib_base;
      size_t mapsize;
      Elf_Addr base_vaddr;
      Elf_Addr base_vlimit;
      caddr_t base_addr;
      Elf_Off data_offset;
      Elf_Addr data_vaddr;
      Elf_Addr data_vlimit;
      caddr_t data_addr;
      int data_prot;
      int data_flags;
      Elf_Addr clear_vaddr;
      caddr_t clear_addr;
      caddr_t clear_page;
      Elf_Addr phdr_vaddr;
      size_t nclear, phsize;
      Elf_Addr bss_vaddr;
      Elf_Addr bss_vlimit;
      caddr_t bss_addr;
      Elf_Word stack_flags;
      Elf_Addr relro_page;
      size_t relro_size;
      Elf_Addr note_start;
      Elf_Addr note_end;
  
      hdr = get_elf_header(fd, path);
      if (hdr == NULL)
  	return (NULL);
  
      if (__ld_sharedlib_base) {
  	shlib_base = (void *)(intptr_t)strtoul(__ld_sharedlib_base, NULL, 0);
      } else {
  	shlib_base = NULL;
      }
  
      /*
       * Scan the program header entries, and save key information.
       *
       * We expect that the loadable segments are ordered by load address.
       */
      phdr = (Elf_Phdr *) ((char *)hdr + hdr->e_phoff);
      phsize  = hdr->e_phnum * sizeof (phdr[0]);
      phlimit = phdr + hdr->e_phnum;
      nsegs = -1;
      phdyn = phinterp = phtls = NULL;
      phdr_vaddr = 0;
      relro_page = 0;
      relro_size = 0;
      note_start = 0;
      note_end = 0;
      segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
      stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
      while (phdr < phlimit) {
  	switch (phdr->p_type) {
  
  	case PT_INTERP:
  	    phinterp = phdr;
  	    break;
  
  	case PT_LOAD:
  	    segs[++nsegs] = phdr;
  	    if ((segs[nsegs]->p_align & (PAGE_SIZE - 1)) != 0) {
  		_rtld_error("%s: PT_LOAD segment %d not page-aligned",
  		    path, nsegs);
  		goto error;
  	    }
  	    break;
  
  	case PT_PHDR:
  	    phdr_vaddr = phdr->p_vaddr;
  	    phsize = phdr->p_memsz;
  	    break;
  
  	case PT_DYNAMIC:
  	    phdyn = phdr;
  	    break;
  
  	case PT_TLS:
  	    phtls = phdr;
  	    break;
  
  	case PT_GNU_STACK:
  	    stack_flags = phdr->p_flags;
  	    break;
  
  	case PT_GNU_RELRO:
  	    relro_page = phdr->p_vaddr;
  	    relro_size = phdr->p_memsz;
  	    break;
  
  	case PT_NOTE:
  	    if (phdr->p_offset > PAGE_SIZE ||
  	      phdr->p_offset + phdr->p_filesz > PAGE_SIZE)
  		break;
  	    note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
  	    note_end = note_start + phdr->p_filesz;
  	    break;
  	}
  
  	++phdr;
      }
      if (phdyn == NULL) {
  	_rtld_error("%s: object is not dynamically-linked", path);
  	goto error;
      }
  
      if (nsegs < 0) {
  	_rtld_error("%s: too few PT_LOAD segments", path);
  	goto error;
      }
  
      /*
       * Map the entire address space of the object, to stake out our
       * contiguous region, and to establish the base address for relocation.
       */
      base_vaddr = trunc_page(segs[0]->p_vaddr);
      base_vlimit = round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz);
      mapsize = base_vlimit - base_vaddr;
      base_addr = (caddr_t) base_vaddr;
  
      if (base_addr == NULL && shlib_base) {
  	size_t limit = 1024 * 256 * 1024;
  	size_t offset;
  
  	for (offset = 0; offset < limit; offset += 256 * 1024) {
  		mapbase = mmap(shlib_base + offset, mapsize,
  			       PROT_NONE,
  			       MAP_ANON | MAP_PRIVATE | MAP_NOCORE |
  			       MAP_TRYFIXED,
  			       -1, 0);
  		if (mapbase != MAP_FAILED)
  			break;
  	}
      } else {
  	mapbase = mmap(base_addr, mapsize,
  		       PROT_NONE,
  		       MAP_ANON | MAP_PRIVATE | MAP_NOCORE,
  		       -1, 0);
      }
      if (mapbase == (caddr_t) -1) {
  	_rtld_error("%s: mmap of entire address space failed: %s",
  	  path, rtld_strerror(errno));
  	goto error;
      }
      if (base_addr != NULL && mapbase != base_addr) {
  	_rtld_error("%s: mmap returned wrong address: wanted %p, got %p",
  	  path, base_addr, mapbase);
  	goto error1;
      }
  
      for (i = 0; i <= nsegs; i++) {
  	/* Overlay the segment onto the proper region. */
  	data_offset = trunc_page(segs[i]->p_offset);
  	data_vaddr = trunc_page(segs[i]->p_vaddr);
  	data_vlimit = round_page(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 (mmap(data_addr, data_vlimit - data_vaddr, data_prot,
  	  data_flags, fd, data_offset) == (caddr_t) -1) {
  	    _rtld_error("%s: mmap of data failed: %s", path,
  		rtld_strerror(errno));
  	    goto error1;
  	}
  
  	/* Do BSS setup */
  	if (segs[i]->p_filesz != segs[i]->p_memsz) {
  
  	    /* 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 + (trunc_page(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, PAGE_SIZE, data_prot|PROT_WRITE)) {
  			_rtld_error("%s: mprotect failed: %s", path,
  			    rtld_strerror(errno));
  			goto error1;
  		}
  
  		memset(clear_addr, 0, nclear);
  
  		/*
  		 * reset the data protection back, enable the segment to be
  		 * coredumped since we modified it.
  		 */
  		if ((data_prot & PROT_WRITE) == 0) {
  		    madvise(clear_page, PAGE_SIZE, MADV_CORE);
  		    mprotect(clear_page, PAGE_SIZE, data_prot);
  		}
  	    }
  
  	    /* Overlay the BSS segment onto the proper region. */
  	    bss_vaddr = data_vlimit;
  	    bss_vlimit = round_page(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) == (caddr_t)-1) {
  		    _rtld_error("%s: mmap of bss failed: %s", path,
  			rtld_strerror(errno));
  		    goto error1;
  		}
  	    }
  	}
  
  	if (phdr_vaddr == 0 && data_offset <= hdr->e_phoff &&
  	  (data_vlimit - data_vaddr + data_offset) >=
  	  (hdr->e_phoff + hdr->e_phnum * sizeof (Elf_Phdr))) {
  	    phdr_vaddr = data_vaddr + hdr->e_phoff - data_offset;
  	}
      }
  
      obj = obj_new();
      if (sb != NULL) {
  	obj->dev = sb->st_dev;
  	obj->ino = sb->st_ino;
      }
      obj->mapbase = mapbase;
      obj->mapsize = mapsize;
      obj->textsize = round_page(segs[0]->p_vaddr + segs[0]->p_memsz) -
        base_vaddr;
      obj->vaddrbase = base_vaddr;
      obj->relocbase = mapbase - base_vaddr;
      obj->dynamic = (const Elf_Dyn *) (obj->relocbase + phdyn->p_vaddr);
      if (hdr->e_entry != 0)
  	obj->entry = (caddr_t) (obj->relocbase + hdr->e_entry);
      if (phdr_vaddr != 0) {
  	obj->phdr = (const Elf_Phdr *) (obj->relocbase + phdr_vaddr);
      } else {
  	obj->phdr = malloc(phsize);
  	if (obj->phdr == NULL) {
  	    obj_free(obj);
  	    _rtld_error("%s: cannot allocate program header", path);
  	    goto error1;
  	}
  	memcpy((char *)obj->phdr, (char *)hdr + hdr->e_phoff, phsize);
  	obj->phdr_alloc = true;
      }
      obj->phsize = phsize;
      if (phinterp != NULL)
  	obj->interp = (const char *) (obj->relocbase + phinterp->p_vaddr);
      if (phtls != NULL) {
  	tls_dtv_generation++;
  	obj->tlsindex = ++tls_max_index;
  	obj->tlssize = phtls->p_memsz;
  	obj->tlsalign = phtls->p_align;
  	obj->tlsinitsize = phtls->p_filesz;
  	obj->tlsinit = mapbase + phtls->p_vaddr;
      }
      obj->stack_flags = stack_flags;
      if (relro_size) {
          obj->relro_page = obj->relocbase + trunc_page(relro_page);
          obj->relro_size = round_page(relro_size);
      }
      if (note_start < note_end)
         digest_notes(obj, note_start, note_end);
      munmap(hdr, PAGE_SIZE);
      return (obj);
  
  error1:
      munmap(mapbase, mapsize);
  error:
      munmap(hdr, PAGE_SIZE);
      return (NULL);
  }
  
  static Elf_Ehdr *
  get_elf_header(int fd, const char *path)
  {
  	Elf_Ehdr *hdr;
  
  	/* DragonFly mmap does not have MAP_PREFAULT_READ */
  	hdr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE, fd, 0);
  	if (hdr == (Elf_Ehdr *)MAP_FAILED) {
  		_rtld_error("%s: read error: %s", path, rtld_strerror(errno));
  		return (NULL);
  	}
  
  	/* Make sure the file is valid */
  	if (!IS_ELF(*hdr)) {
  		_rtld_error("%s: invalid file format", path);
  		goto error;
  	}
  	if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
  	    hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
  		_rtld_error("%s: unsupported file layout", path);
  		goto error;
  	}
  	if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
  	    hdr->e_version != EV_CURRENT) {
  		_rtld_error("%s: unsupported file version", path);
  		goto error;
  	}
  	if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
  		_rtld_error("%s: unsupported file type", path);
  		goto error;
  	}
  	if (hdr->e_machine != ELF_TARG_MACH) {
  		_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.
  	 */
  	if (hdr->e_phentsize != sizeof(Elf_Phdr)) {
  		_rtld_error(
  	    "%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)", path);
  		goto error;
  	}
  	if (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) >
  	    (size_t)PAGE_SIZE) {
  		_rtld_error("%s: program header too large", path);
  		goto error;
  	}
  	return (hdr);
  
  error:
  	munmap(hdr, PAGE_SIZE);
  	return (NULL);
  }
  
  void
  obj_free(Obj_Entry *obj)
  {
      Objlist_Entry *elm;
  
      if (obj->tls_done)
  	free_tls_offset(obj);
      while (obj->needed != NULL) {
  	Needed_Entry *needed = obj->needed;
  	obj->needed = needed->next;
  	free(needed);
      }
      while (!STAILQ_EMPTY(&obj->names)) {
  	Name_Entry *entry = STAILQ_FIRST(&obj->names);
  	STAILQ_REMOVE_HEAD(&obj->names, link);
  	free(entry);
      }
      while (!STAILQ_EMPTY(&obj->dldags)) {
  	elm = STAILQ_FIRST(&obj->dldags);
  	STAILQ_REMOVE_HEAD(&obj->dldags, link);
  	free(elm);
      }
      while (!STAILQ_EMPTY(&obj->dagmembers)) {
  	elm = STAILQ_FIRST(&obj->dagmembers);
  	STAILQ_REMOVE_HEAD(&obj->dagmembers, link);
  	free(elm);
      }
      if (obj->vertab)
  	free(obj->vertab);
      if (obj->origin_path)
  	free(obj->origin_path);
      if (obj->z_origin)
  	free(obj->rpath);
      if (obj->priv)
  	free(obj->priv);
      if (obj->path)
  	free(obj->path);
      if (obj->phdr_alloc)
  	free((void *)obj->phdr);
      free(obj);
  }
  
  Obj_Entry *
  obj_new(void)
  {
      Obj_Entry *obj;
  
      obj = CNEW(Obj_Entry);
      STAILQ_INIT(&obj->dldags);
      STAILQ_INIT(&obj->dagmembers);
      STAILQ_INIT(&obj->names);
      return obj;
  }
  
  /*
   * Given a set of ELF protection flags, return the corresponding protection
   * flags for MMAP.
   */
  int
  convert_prot(int elfflags)
  {
      int prot = 0;
      if (elfflags & PF_R)
  	prot |= PROT_READ;
      if (elfflags & PF_W)
  	prot |= PROT_WRITE;
      if (elfflags & PF_X)
  	prot |= PROT_EXEC;
      return prot;
  }
  
  static int
  convert_flags(int elfflags)
  {
      int flags = MAP_PRIVATE; /* All mappings are private */
  
      /*
       * Readonly mappings are marked "MAP_NOCORE", because they can be
       * reconstructed by a debugger.
       */
      if (!(elfflags & PF_W))
  	flags |= MAP_NOCORE;
      return flags;
  }
  