f5392eb672
On error, mmap(2) returns MAP_FAILED. There is no need to use its definition or to cast. Sponsored by: The FreeBSD Foundation MFC after: 1 week
486 lines
13 KiB
C
486 lines
13 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright 1996-1998 John D. Polstra.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "debug.h"
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#include "rtld.h"
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static Elf_Ehdr *get_elf_header(int, const char *, const struct stat *);
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static int convert_flags(int); /* Elf flags -> mmap flags */
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int __getosreldate(void);
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/*
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* Map a shared object into memory. The "fd" argument is a file descriptor,
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* which must be open on the object and positioned at its beginning.
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* The "path" argument is a pathname that is used only for error messages.
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*
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* The return value is a pointer to a newly-allocated Obj_Entry structure
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* for the shared object. Returns NULL on failure.
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*/
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Obj_Entry *
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map_object(int fd, const char *path, const struct stat *sb)
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{
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Obj_Entry *obj;
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Elf_Ehdr *hdr;
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int i;
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Elf_Phdr *phdr;
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Elf_Phdr *phlimit;
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Elf_Phdr **segs;
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int nsegs;
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Elf_Phdr *phdyn;
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Elf_Phdr *phinterp;
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Elf_Phdr *phtls;
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caddr_t mapbase;
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size_t mapsize;
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Elf_Addr base_vaddr;
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Elf_Addr base_vlimit;
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caddr_t base_addr;
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int base_flags;
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Elf_Off data_offset;
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Elf_Addr data_vaddr;
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Elf_Addr data_vlimit;
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caddr_t data_addr;
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int data_prot;
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int data_flags;
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Elf_Addr clear_vaddr;
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caddr_t clear_addr;
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caddr_t clear_page;
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Elf_Addr phdr_vaddr;
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size_t nclear, phsize;
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Elf_Addr bss_vaddr;
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Elf_Addr bss_vlimit;
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caddr_t bss_addr;
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Elf_Word stack_flags;
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Elf_Addr relro_page;
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size_t relro_size;
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Elf_Addr note_start;
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Elf_Addr note_end;
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char *note_map;
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size_t note_map_len;
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Elf_Addr text_end;
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hdr = get_elf_header(fd, path, sb);
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if (hdr == NULL)
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return (NULL);
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/*
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* Scan the program header entries, and save key information.
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*
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* We expect that the loadable segments are ordered by load address.
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*/
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phdr = (Elf_Phdr *)((char *)hdr + hdr->e_phoff);
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phsize = hdr->e_phnum * sizeof (phdr[0]);
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phlimit = phdr + hdr->e_phnum;
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nsegs = -1;
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phdyn = phinterp = phtls = NULL;
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phdr_vaddr = 0;
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relro_page = 0;
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relro_size = 0;
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note_start = 0;
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note_end = 0;
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note_map = NULL;
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note_map_len = 0;
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segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
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stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
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text_end = 0;
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while (phdr < phlimit) {
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switch (phdr->p_type) {
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case PT_INTERP:
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phinterp = phdr;
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break;
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case PT_LOAD:
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segs[++nsegs] = phdr;
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if ((segs[nsegs]->p_align & (PAGE_SIZE - 1)) != 0) {
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_rtld_error("%s: PT_LOAD segment %d not page-aligned",
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path, nsegs);
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goto error;
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}
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if ((segs[nsegs]->p_flags & PF_X) == PF_X) {
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text_end = MAX(text_end,
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round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz));
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}
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break;
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case PT_PHDR:
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phdr_vaddr = phdr->p_vaddr;
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phsize = phdr->p_memsz;
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break;
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case PT_DYNAMIC:
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phdyn = phdr;
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break;
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case PT_TLS:
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phtls = phdr;
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break;
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case PT_GNU_STACK:
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stack_flags = phdr->p_flags;
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break;
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case PT_GNU_RELRO:
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relro_page = phdr->p_vaddr;
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relro_size = phdr->p_memsz;
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break;
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case PT_NOTE:
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if (phdr->p_offset > PAGE_SIZE ||
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phdr->p_offset + phdr->p_filesz > PAGE_SIZE) {
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note_map_len = round_page(phdr->p_offset +
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phdr->p_filesz) - trunc_page(phdr->p_offset);
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note_map = mmap(NULL, note_map_len, PROT_READ,
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MAP_PRIVATE, fd, trunc_page(phdr->p_offset));
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if (note_map == MAP_FAILED) {
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_rtld_error("%s: error mapping PT_NOTE (%d)", path, errno);
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goto error;
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}
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note_start = (Elf_Addr)(note_map + phdr->p_offset -
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trunc_page(phdr->p_offset));
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} else {
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note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
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}
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note_end = note_start + phdr->p_filesz;
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break;
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}
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++phdr;
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}
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if (phdyn == NULL) {
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_rtld_error("%s: object is not dynamically-linked", path);
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goto error;
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}
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if (nsegs < 0) {
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_rtld_error("%s: too few PT_LOAD segments", path);
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goto error;
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}
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/*
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* Map the entire address space of the object, to stake out our
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* contiguous region, and to establish the base address for relocation.
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*/
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base_vaddr = trunc_page(segs[0]->p_vaddr);
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base_vlimit = round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz);
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mapsize = base_vlimit - base_vaddr;
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base_addr = (caddr_t) base_vaddr;
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base_flags = __getosreldate() >= P_OSREL_MAP_GUARD ? MAP_GUARD :
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MAP_PRIVATE | MAP_ANON | MAP_NOCORE;
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if (npagesizes > 1 && round_page(segs[0]->p_filesz) >= pagesizes[1])
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base_flags |= MAP_ALIGNED_SUPER;
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if (base_vaddr != 0)
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base_flags |= MAP_FIXED | MAP_EXCL;
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mapbase = mmap(base_addr, mapsize, PROT_NONE, base_flags, -1, 0);
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if (mapbase == MAP_FAILED) {
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_rtld_error("%s: mmap of entire address space failed: %s",
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path, rtld_strerror(errno));
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goto error;
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}
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if (base_addr != NULL && mapbase != base_addr) {
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_rtld_error("%s: mmap returned wrong address: wanted %p, got %p",
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path, base_addr, mapbase);
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goto error1;
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}
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for (i = 0; i <= nsegs; i++) {
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/* Overlay the segment onto the proper region. */
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data_offset = trunc_page(segs[i]->p_offset);
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data_vaddr = trunc_page(segs[i]->p_vaddr);
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data_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_filesz);
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data_addr = mapbase + (data_vaddr - base_vaddr);
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data_prot = convert_prot(segs[i]->p_flags);
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data_flags = convert_flags(segs[i]->p_flags) | MAP_FIXED;
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if (data_vlimit != data_vaddr &&
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mmap(data_addr, data_vlimit - data_vaddr, data_prot,
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data_flags | MAP_PREFAULT_READ, fd, data_offset) == MAP_FAILED) {
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_rtld_error("%s: mmap of data failed: %s", path,
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rtld_strerror(errno));
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goto error1;
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}
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/* Do BSS setup */
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if (segs[i]->p_filesz != segs[i]->p_memsz) {
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/* Clear any BSS in the last page of the segment. */
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clear_vaddr = segs[i]->p_vaddr + segs[i]->p_filesz;
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clear_addr = mapbase + (clear_vaddr - base_vaddr);
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clear_page = mapbase + (trunc_page(clear_vaddr) - base_vaddr);
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if ((nclear = data_vlimit - clear_vaddr) > 0) {
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/* Make sure the end of the segment is writable */
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if ((data_prot & PROT_WRITE) == 0 && -1 ==
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mprotect(clear_page, PAGE_SIZE, data_prot|PROT_WRITE)) {
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_rtld_error("%s: mprotect failed: %s", path,
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rtld_strerror(errno));
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goto error1;
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}
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memset(clear_addr, 0, nclear);
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/* Reset the data protection back */
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if ((data_prot & PROT_WRITE) == 0)
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mprotect(clear_page, PAGE_SIZE, data_prot);
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}
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/* Overlay the BSS segment onto the proper region. */
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bss_vaddr = data_vlimit;
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bss_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_memsz);
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bss_addr = mapbase + (bss_vaddr - base_vaddr);
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if (bss_vlimit > bss_vaddr) { /* There is something to do */
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if (mmap(bss_addr, bss_vlimit - bss_vaddr, data_prot,
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data_flags | MAP_ANON, -1, 0) == MAP_FAILED) {
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_rtld_error("%s: mmap of bss failed: %s", path,
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rtld_strerror(errno));
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goto error1;
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}
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}
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}
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if (phdr_vaddr == 0 && data_offset <= hdr->e_phoff &&
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(data_vlimit - data_vaddr + data_offset) >=
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(hdr->e_phoff + hdr->e_phnum * sizeof (Elf_Phdr))) {
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phdr_vaddr = data_vaddr + hdr->e_phoff - data_offset;
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}
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}
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obj = obj_new();
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if (sb != NULL) {
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obj->dev = sb->st_dev;
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obj->ino = sb->st_ino;
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}
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obj->mapbase = mapbase;
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obj->mapsize = mapsize;
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obj->vaddrbase = base_vaddr;
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obj->relocbase = mapbase - base_vaddr;
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obj->dynamic = (const Elf_Dyn *)(obj->relocbase + phdyn->p_vaddr);
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if (hdr->e_entry != 0)
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obj->entry = (caddr_t)(obj->relocbase + hdr->e_entry);
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if (phdr_vaddr != 0) {
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obj->phdr = (const Elf_Phdr *)(obj->relocbase + phdr_vaddr);
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} else {
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obj->phdr = malloc(phsize);
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if (obj->phdr == NULL) {
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obj_free(obj);
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_rtld_error("%s: cannot allocate program header", path);
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goto error1;
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}
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memcpy(__DECONST(char *, obj->phdr), (char *)hdr + hdr->e_phoff, phsize);
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obj->phdr_alloc = true;
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}
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obj->phsize = phsize;
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if (phinterp != NULL)
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obj->interp = (const char *)(obj->relocbase + phinterp->p_vaddr);
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if (phtls != NULL) {
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tls_dtv_generation++;
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obj->tlsindex = ++tls_max_index;
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obj->tlssize = phtls->p_memsz;
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obj->tlsalign = phtls->p_align;
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obj->tlsinitsize = phtls->p_filesz;
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obj->tlsinit = mapbase + phtls->p_vaddr;
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}
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obj->stack_flags = stack_flags;
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obj->relro_page = obj->relocbase + trunc_page(relro_page);
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obj->relro_size = round_page(relro_size);
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if (note_start < note_end)
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digest_notes(obj, note_start, note_end);
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if (note_map != NULL)
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munmap(note_map, note_map_len);
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munmap(hdr, PAGE_SIZE);
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return (obj);
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error1:
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munmap(mapbase, mapsize);
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error:
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if (note_map != NULL && note_map != MAP_FAILED)
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munmap(note_map, note_map_len);
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munmap(hdr, PAGE_SIZE);
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return (NULL);
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}
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static Elf_Ehdr *
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get_elf_header(int fd, const char *path, const struct stat *sbp)
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{
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Elf_Ehdr *hdr;
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/* Make sure file has enough data for the ELF header */
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if (sbp != NULL && sbp->st_size < (off_t)sizeof(Elf_Ehdr)) {
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_rtld_error("%s: invalid file format", path);
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return (NULL);
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}
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hdr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE | MAP_PREFAULT_READ,
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fd, 0);
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if (hdr == MAP_FAILED) {
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_rtld_error("%s: read error: %s", path, rtld_strerror(errno));
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return (NULL);
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}
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/* Make sure the file is valid */
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if (!IS_ELF(*hdr)) {
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_rtld_error("%s: invalid file format", path);
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goto error;
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}
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if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
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hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
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_rtld_error("%s: unsupported file layout", path);
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goto error;
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}
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if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
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hdr->e_version != EV_CURRENT) {
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_rtld_error("%s: unsupported file version", path);
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goto error;
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}
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if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
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_rtld_error("%s: unsupported file type", path);
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goto error;
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}
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if (hdr->e_machine != ELF_TARG_MACH) {
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_rtld_error("%s: unsupported machine", path);
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goto error;
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}
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/*
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* We rely on the program header being in the first page. This is
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* not strictly required by the ABI specification, but it seems to
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* always true in practice. And, it simplifies things considerably.
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*/
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if (hdr->e_phentsize != sizeof(Elf_Phdr)) {
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_rtld_error(
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"%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)", path);
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goto error;
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}
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if (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) >
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(size_t)PAGE_SIZE) {
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_rtld_error("%s: program header too large", path);
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goto error;
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}
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return (hdr);
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error:
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munmap(hdr, PAGE_SIZE);
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return (NULL);
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}
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void
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obj_free(Obj_Entry *obj)
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{
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Objlist_Entry *elm;
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if (obj->tls_done)
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free_tls_offset(obj);
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while (obj->needed != NULL) {
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Needed_Entry *needed = obj->needed;
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obj->needed = needed->next;
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free(needed);
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}
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while (!STAILQ_EMPTY(&obj->names)) {
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Name_Entry *entry = STAILQ_FIRST(&obj->names);
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STAILQ_REMOVE_HEAD(&obj->names, link);
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free(entry);
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}
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while (!STAILQ_EMPTY(&obj->dldags)) {
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elm = STAILQ_FIRST(&obj->dldags);
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STAILQ_REMOVE_HEAD(&obj->dldags, link);
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free(elm);
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}
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while (!STAILQ_EMPTY(&obj->dagmembers)) {
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elm = STAILQ_FIRST(&obj->dagmembers);
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STAILQ_REMOVE_HEAD(&obj->dagmembers, link);
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free(elm);
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}
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if (obj->vertab)
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free(obj->vertab);
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if (obj->origin_path)
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free(obj->origin_path);
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if (obj->z_origin)
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free(__DECONST(void*, obj->rpath));
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if (obj->priv)
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free(obj->priv);
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if (obj->path)
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free(obj->path);
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if (obj->phdr_alloc)
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free(__DECONST(void *, obj->phdr));
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free(obj);
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}
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Obj_Entry *
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obj_new(void)
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{
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Obj_Entry *obj;
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obj = CNEW(Obj_Entry);
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STAILQ_INIT(&obj->dldags);
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STAILQ_INIT(&obj->dagmembers);
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STAILQ_INIT(&obj->names);
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return obj;
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}
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/*
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* Given a set of ELF protection flags, return the corresponding protection
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* flags for MMAP.
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*/
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int
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convert_prot(int elfflags)
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{
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int prot = 0;
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if (elfflags & PF_R)
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prot |= PROT_READ;
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if (elfflags & PF_W)
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prot |= PROT_WRITE;
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if (elfflags & PF_X)
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prot |= PROT_EXEC;
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return prot;
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}
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static int
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convert_flags(int elfflags)
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{
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int flags = MAP_PRIVATE; /* All mappings are private */
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/*
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* Readonly mappings are marked "MAP_NOCORE", because they can be
|
|
* reconstructed by a debugger.
|
|
*/
|
|
if (!(elfflags & PF_W))
|
|
flags |= MAP_NOCORE;
|
|
return flags;
|
|
}
|