517 lines
14 KiB
C
517 lines
14 KiB
C
/* $NetBSD: rumpuser_dl.c,v 1.33 2020/03/22 13:30:10 pgoyette Exp $ */
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/*
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* Copyright (c) 2009 Antti Kantee. 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
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Load all module link sets and feed symbol table to the kernel.
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* Called during rump bootstrap.
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*/
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/*
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* Solaris libelf.h doesn't support _FILE_OFFSET_BITS=64. Luckily,
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* for this module it doesn't matter.
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*/
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#if defined(__sun__)
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#define RUMPUSER_NO_FILE_OFFSET_BITS
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#endif
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#include "rumpuser_port.h"
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#if !defined(lint)
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__RCSID("$NetBSD: rumpuser_dl.c,v 1.33 2020/03/22 13:30:10 pgoyette Exp $");
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#endif /* !lint */
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/evcnt.h>
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#include <assert.h>
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#include <dlfcn.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <stdio.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 <rump/rumpuser.h>
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#if defined(__ELF__) && defined(HAVE_DLINFO)
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#include <elf.h>
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#include <link.h>
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static size_t symtabsize = 0, strtabsize = 0;
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static size_t symtaboff = 0, strtaboff = 0;
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static uint8_t *symtab = NULL;
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static char *strtab = NULL;
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static unsigned char eident;
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/* nb5 compat */
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#ifndef Elf_Symindx
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#define Elf_Symindx uint32_t
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#endif
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static void *
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reservespace(void *store, size_t *storesize,
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size_t storeoff, size_t required)
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{
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size_t chunk, newsize;
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assert(storeoff <= *storesize);
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chunk = *storesize - storeoff;
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if (chunk >= required)
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return store;
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newsize = *storesize + ((size_t)required - chunk);
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store = realloc(store, newsize);
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if (store == NULL) {
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return NULL;
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}
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*((uint8_t *)store + storeoff) = '\0';
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*storesize = newsize;
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return store;
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}
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/*
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* Macros to make handling elf32/64 in the code a little saner.
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*/
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#define DYNn_GETMEMBER(base, n, thevar, result) \
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do { \
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if (eident == ELFCLASS32) { \
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const Elf32_Dyn *dyn = base; \
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/*LINTED*/ \
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result = dyn[n].thevar; \
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} else { \
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const Elf64_Dyn *dyn = base; \
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/*LINTED*/ \
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result = dyn[n].thevar; \
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} \
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} while (/*CONSTCOND*/0)
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#define SYMn_GETMEMBER(base, n, thevar, result) \
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do { \
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if (eident == ELFCLASS32) { \
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const Elf32_Sym *sym = base; \
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/*LINTED*/ \
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result = sym[n].thevar; \
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} else { \
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const Elf64_Sym *sym = base; \
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/*LINTED*/ \
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result = sym[n].thevar; \
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} \
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} while (/*CONSTCOND*/0)
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#define SYMn_SETMEMBER(base, n, thevar, value) \
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do { \
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if (eident == ELFCLASS32) { \
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Elf32_Sym *sym = base; \
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/*LINTED*/ \
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sym[n].thevar = value; \
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} else { \
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Elf64_Sym *sym = base; \
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/*LINTED*/ \
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sym[n].thevar = value; \
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} \
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} while (/*CONSTCOND*/0)
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#define SYM_GETSIZE() ((eident==ELFCLASS32)?sizeof(Elf32_Sym):sizeof(Elf64_Sym))
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/*
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* On NetBSD, the dynamic section pointer values seem to be relative to
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* the address the dso is mapped at. On glibc, they seem to contain
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* the absolute address. I couldn't find anything definite from a quick
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* read of the standard and therefore I will not go and figure beyond ifdef.
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* On Solaris and DragonFly / FreeBSD, the main object works differently
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* ... uuuuh.
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*/
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#if defined(__GLIBC__) && !defined(__mips__)
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#define adjptr(_map_, _ptr_) ((void *)(_ptr_))
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#elif defined(__sun__) || defined(__DragonFly__) || defined(__FreeBSD__)
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#define adjptr(_map_, _ptr_) \
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(ismainobj ? (void *)(_ptr_) : (void *)(_map_->l_addr + (_ptr_)))
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#else
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/* NetBSD and some others, e.g. Linux + musl */
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#define adjptr(_map_, _ptr_) ((void *)(_map_->l_addr + (_ptr_)))
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#endif
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static int
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getsymbols(struct link_map *map, int ismainobj)
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{
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char *str_base;
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void *syms_base = NULL; /* XXXgcc */
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size_t curstrsize;
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const void *ed_base;
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uint64_t ed_tag;
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size_t cursymcount;
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unsigned i;
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if (map->l_addr) {
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if (memcmp((void *)map->l_addr, ELFMAG, SELFMAG) != 0)
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return ENOEXEC;
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eident = *(unsigned char *)(map->l_addr + EI_CLASS);
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if (eident != ELFCLASS32 && eident != ELFCLASS64)
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return ENOEXEC;
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}
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/*
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* ok, we probably have only the main object. instead of going
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* to disk and reading the ehdr, just try to guess the size.
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*/
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if (eident == 0) {
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if (/*CONSTCOND*/sizeof(void *) == 4)
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eident = ELFCLASS32;
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else
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eident = ELFCLASS64;
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}
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/*
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* Find symtab and strtab and their sizes.
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*/
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str_base = NULL;
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curstrsize = 0;
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cursymcount = 0;
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ed_base = map->l_ld;
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DYNn_GETMEMBER(ed_base, 0, d_tag, ed_tag);
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for (i = 0; ed_tag != DT_NULL;) {
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uintptr_t edptr;
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size_t edval;
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Elf_Symindx *hashtab;
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switch (ed_tag) {
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case DT_SYMTAB:
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DYNn_GETMEMBER(ed_base, i, d_un.d_ptr, edptr);
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syms_base = adjptr(map, edptr);
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break;
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case DT_STRTAB:
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DYNn_GETMEMBER(ed_base, i, d_un.d_ptr, edptr);
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str_base = adjptr(map, edptr);
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break;
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case DT_STRSZ:
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DYNn_GETMEMBER(ed_base, i, d_un.d_val, edval);
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curstrsize = edval;
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break;
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case DT_HASH:
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DYNn_GETMEMBER(ed_base, i, d_un.d_ptr, edptr);
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hashtab = (Elf_Symindx *)adjptr(map, edptr);
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cursymcount = hashtab[1];
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break;
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#ifdef DT_GNU_HASH
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/*
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* DT_GNU_HASH is a bit more complicated than DT_HASH
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* in this regard since apparently there is no field
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* telling us the total symbol count. Instead, we look
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* for the last valid hash bucket and add its chain length
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* to the bucket's base index.
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*/
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case DT_GNU_HASH: {
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Elf32_Word nbuck, symndx, maskwords, maxchain = 0;
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Elf32_Word *gnuhash, *buckets, *ptr;
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int bi;
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DYNn_GETMEMBER(ed_base, i, d_un.d_ptr, edptr);
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gnuhash = (Elf32_Word *)adjptr(map, edptr);
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nbuck = gnuhash[0];
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symndx = gnuhash[1];
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maskwords = gnuhash[2];
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/*
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* First, find the last valid bucket and grab its index
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*/
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if (eident == ELFCLASS64)
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maskwords *= 2; /* sizeof(*buckets) == 4 */
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buckets = gnuhash + 4 + maskwords;
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for (bi = nbuck-1; bi >= 0; bi--) {
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if (buckets[bi] != 0) {
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maxchain = buckets[bi];
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break;
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}
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}
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if (maxchain == 0 || maxchain < symndx)
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break;
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/*
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* Then, traverse the last chain and count symbols.
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*/
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cursymcount = maxchain;
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ptr = buckets + nbuck + (maxchain - symndx);
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do {
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cursymcount++;
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} while ((*ptr++ & 1) == 0);
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}
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break;
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#endif
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case DT_SYMENT:
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DYNn_GETMEMBER(ed_base, i, d_un.d_val, edval);
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assert(edval == SYM_GETSIZE());
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break;
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default:
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break;
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}
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i++;
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DYNn_GETMEMBER(ed_base, i, d_tag, ed_tag);
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}
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if (str_base == NULL || syms_base == NULL ||
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curstrsize == 0 || cursymcount == 0) {
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fprintf(stderr, "could not find strtab, symtab or their sizes "
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"in %s\n", map->l_name);
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return ENOEXEC;
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}
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/*
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* Make sure we have enough space for the contents of the symbol
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* and string tables we are currently processing. The total used
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* space will be smaller due to undefined symbols we are not
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* interested in.
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*/
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symtab = reservespace(symtab, &symtabsize,
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symtaboff, cursymcount * SYM_GETSIZE());
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strtab = reservespace(strtab, &strtabsize, strtaboff, curstrsize);
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if (symtab == NULL || strtab == NULL) {
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fprintf(stderr, "failed to reserve memory");
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return ENOMEM;
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}
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/* iterate over all symbols in current symtab */
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for (i = 0; i < cursymcount; i++) {
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const char *cursymname;
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int shndx, name;
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uintptr_t value;
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void *csym;
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SYMn_GETMEMBER(syms_base, i, st_shndx, shndx);
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SYMn_GETMEMBER(syms_base, i, st_value, value);
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if (shndx == SHN_UNDEF || value == 0)
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continue;
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/* get symbol name */
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SYMn_GETMEMBER(syms_base, i, st_name, name);
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cursymname = name + str_base;
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/*
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* Only accept symbols which are decidedly in
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* the rump kernel namespace.
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* XXX: quirks, but they wouldn't matter here
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*/
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if (strncmp(cursymname, "rump", 4) != 0 &&
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strncmp(cursymname, "RUMP", 4) != 0 &&
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strncmp(cursymname, "__", 2) != 0) {
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continue;
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}
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memcpy(symtab + symtaboff,
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(const uint8_t *)syms_base + i*SYM_GETSIZE(),SYM_GETSIZE());
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/*
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* set name to point at new strtab, offset symbol value
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* with lib base address.
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*/
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csym = symtab + symtaboff;
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SYMn_SETMEMBER(csym, 0, st_name, strtaboff);
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SYMn_GETMEMBER(csym, 0, st_value, value);
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SYMn_SETMEMBER(csym, 0, st_value,(intptr_t)(value+map->l_addr));
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symtaboff += SYM_GETSIZE();
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strcpy(strtab + strtaboff, cursymname);
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strtaboff += strlen(cursymname)+1;
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}
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return 0;
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}
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static void
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process_object(void *handle,
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rump_modinit_fn domodinit, rump_compload_fn docompload,
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rump_evcntattach_fn doevcntattach)
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{
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const struct modinfo *const *mi_start, *const *mi_end;
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struct rump_component *const *rc, *const *rc_end;
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struct sysctllog;
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typedef void sysctl_setup_func(struct sysctllog **);
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sysctl_setup_func *const *sfp, *const *sfp_end;
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struct evcnt *const *evp, *const *evp_end;
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mi_start = dlsym(handle, "__start_link_set_modules");
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mi_end = dlsym(handle, "__stop_link_set_modules");
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if (mi_start && mi_end)
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domodinit(mi_start, (size_t)(mi_end-mi_start));
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rc = dlsym(handle, "__start_link_set_rump_components");
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rc_end = dlsym(handle, "__stop_link_set_rump_components");
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if (rc && rc_end) {
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for (; rc < rc_end; rc++)
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docompload(*rc);
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assert(rc == rc_end);
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}
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/* handle link_set_sysctl_funcs */
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sfp = dlsym(handle, "__start_link_set_sysctl_funcs");
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sfp_end = dlsym(handle, "__stop_link_set_sysctl_funcs");
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if (sfp && sfp_end) {
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for (; sfp < sfp_end; sfp++)
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(**sfp)(NULL);
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assert(sfp == sfp_end);
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}
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/* handle link_set_evcnts */
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evp = dlsym(handle, "__start_link_set_evcnts");
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evp_end = dlsym(handle, "__stop_link_set_evcnts");
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if (evp && evp_end) {
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for (; evp < evp_end; evp++)
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doevcntattach(*evp);
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assert(evp == evp_end);
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}
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}
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/*
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* Get the linkmap from the dynlinker. Try to load kernel modules
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* from all objects in the linkmap.
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*/
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void
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rumpuser_dl_bootstrap(rump_modinit_fn domodinit,
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rump_symload_fn symload, rump_compload_fn compload,
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rump_evcntattach_fn doevcntattach)
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{
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struct link_map *map, *origmap, *mainmap;
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void *mainhandle;
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int error;
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mainhandle = dlopen(NULL, RTLD_NOW);
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/* Will be null if statically linked so just return */
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if (mainhandle == NULL)
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return;
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if (dlinfo(mainhandle, RTLD_DI_LINKMAP, &mainmap) == -1) {
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fprintf(stderr, "warning: rumpuser module bootstrap "
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"failed: %s\n", dlerror());
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return;
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}
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origmap = mainmap;
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/*
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* Use a heuristic to determine if we are static linked.
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* A dynamically linked binary should always have at least
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* two objects: itself and ld.so.
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*
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* In a statically linked binary with glibc the linkmap
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* contains some "info" that leads to a segfault. Since we
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* can't really do anything useful in here without ld.so, just
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* simply bail and let the symbol references in librump do the
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* right things.
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*/
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if (origmap->l_next == NULL && origmap->l_prev == NULL) {
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dlclose(mainhandle);
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return;
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}
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/*
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* Process last->first because that's the most probable
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* order for dependencies
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*/
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for (; origmap->l_next; origmap = origmap->l_next)
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continue;
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/*
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* Build symbol table to hand to the rump kernel. Do this by
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* iterating over all rump libraries and collecting symbol
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* addresses and relocation info.
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*/
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error = 0;
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for (map = origmap; map && !error; map = map->l_prev) {
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if (strstr(map->l_name, "librump") != NULL || map == mainmap)
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error = getsymbols(map, map == mainmap);
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}
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if (error == 0) {
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void *trimmedsym, *trimmedstr;
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/*
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* Allocate optimum-sized memory for storing tables
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* and feed to kernel. If memory allocation fails,
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* just give the ones with extra context (although
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* I'm pretty sure we'll die moments later due to
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* memory running out).
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*/
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if ((trimmedsym = malloc(symtaboff)) != NULL) {
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memcpy(trimmedsym, symtab, symtaboff);
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} else {
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trimmedsym = symtab;
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symtab = NULL;
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}
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if ((trimmedstr = malloc(strtaboff)) != NULL) {
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memcpy(trimmedstr, strtab, strtaboff);
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} else {
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trimmedstr = strtab;
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strtab = NULL;
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}
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symload(trimmedsym, symtaboff, trimmedstr, strtaboff);
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}
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free(symtab);
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free(strtab);
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/*
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* Next, load modules and components.
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*
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* Simply loop through all objects, ones unrelated to rump kernels
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* will not contain link_set_rump_components (well, not including
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* "sabotage", but that needs to be solved at another level anyway).
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*/
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for (map = origmap; map; map = map->l_prev) {
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void *handle;
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if (map == mainmap) {
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handle = mainhandle;
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} else {
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handle = dlopen(map->l_name, RTLD_LAZY);
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if (handle == NULL)
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continue;
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}
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process_object(handle, domodinit, compload, doevcntattach);
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if (map != mainmap)
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dlclose(handle);
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}
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}
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#else
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/*
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|
* no dynamic linking supported
|
|
*/
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|
void
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|
rumpuser_dl_bootstrap(rump_modinit_fn domodinit,
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|
rump_symload_fn symload, rump_compload_fn compload,
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|
rump_evcntattach_fn doevcntattach)
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|
{
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|
|
|
return;
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|
}
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#endif
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