05eb11cbc4
This fixes a race condition where another thread may fork() before CLOEXEC is set, unintentionally passing the descriptor to the child process. This commit only adds O_CLOEXEC flags to open() or openat() calls where no fcntl(fd, F_SETFD, FD_CLOEXEC) follows. The separate fcntl() call still leaves a race window so it should be fixed later.
412 lines
10 KiB
C
412 lines
10 KiB
C
/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. 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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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS 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
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* OR 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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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)nlist.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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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 <sys/file.h>
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#include <arpa/inet.h>
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#include <errno.h>
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#include <a.out.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include "un-namespace.h"
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#define _NLIST_DO_AOUT
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#define _NLIST_DO_ELF
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#ifdef _NLIST_DO_ELF
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#include <machine/elf.h>
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#include <elf-hints.h>
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#endif
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int __fdnlist(int, struct nlist *);
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int __aout_fdnlist(int, struct nlist *);
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int __elf_fdnlist(int, struct nlist *);
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int
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nlist(name, list)
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const char *name;
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struct nlist *list;
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{
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int fd, n;
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fd = _open(name, O_RDONLY | O_CLOEXEC, 0);
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if (fd < 0)
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return (-1);
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n = __fdnlist(fd, list);
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(void)_close(fd);
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return (n);
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}
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static struct nlist_handlers {
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int (*fn)(int fd, struct nlist *list);
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} nlist_fn[] = {
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#ifdef _NLIST_DO_AOUT
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{ __aout_fdnlist },
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#endif
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#ifdef _NLIST_DO_ELF
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{ __elf_fdnlist },
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#endif
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};
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int
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__fdnlist(fd, list)
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int fd;
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struct nlist *list;
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{
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int n = -1, i;
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for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) {
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n = (nlist_fn[i].fn)(fd, list);
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if (n != -1)
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break;
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}
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return (n);
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}
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#define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
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#ifdef _NLIST_DO_AOUT
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int
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__aout_fdnlist(fd, list)
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int fd;
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struct nlist *list;
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{
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struct nlist *p, *symtab;
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caddr_t strtab, a_out_mmap;
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off_t stroff, symoff;
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u_long symsize;
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int nent;
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struct exec * exec;
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struct stat st;
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/* check that file is at least as large as struct exec! */
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if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec)))
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return (-1);
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/* Check for files too large to mmap. */
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if (st.st_size > SIZE_T_MAX) {
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errno = EFBIG;
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return (-1);
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}
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/*
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* Map the whole a.out file into our address space.
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* We then find the string table withing this area.
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* We do not just mmap the string table, as it probably
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* does not start at a page boundary - we save ourselves a
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* lot of nastiness by mmapping the whole file.
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*
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* This gives us an easy way to randomly access all the strings,
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* without making the memory allocation permanent as with
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* malloc/free (i.e., munmap will return it to the system).
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*/
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a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0);
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if (a_out_mmap == MAP_FAILED)
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return (-1);
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exec = (struct exec *)a_out_mmap;
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if (N_BADMAG(*exec)) {
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munmap(a_out_mmap, (size_t)st.st_size);
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return (-1);
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}
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symoff = N_SYMOFF(*exec);
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symsize = exec->a_syms;
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stroff = symoff + symsize;
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/* find the string table in our mmapped area */
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strtab = a_out_mmap + stroff;
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symtab = (struct nlist *)(a_out_mmap + symoff);
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/*
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* clean out any left-over information for all valid entries.
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* Type and value defined to be 0 if not found; historical
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* versions cleared other and desc as well. Also figure out
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* the largest string length so don't read any more of the
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* string table than we have to.
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*
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* XXX clearing anything other than n_type and n_value violates
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* the semantics given in the man page.
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*/
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nent = 0;
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for (p = list; !ISLAST(p); ++p) {
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p->n_type = 0;
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p->n_other = 0;
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p->n_desc = 0;
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p->n_value = 0;
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++nent;
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}
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while (symsize > 0) {
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int soff;
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symsize-= sizeof(struct nlist);
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soff = symtab->n_un.n_strx;
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if (soff != 0 && (symtab->n_type & N_STAB) == 0)
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for (p = list; !ISLAST(p); p++)
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if (!strcmp(&strtab[soff], p->n_un.n_name)) {
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p->n_value = symtab->n_value;
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p->n_type = symtab->n_type;
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p->n_desc = symtab->n_desc;
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p->n_other = symtab->n_other;
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if (--nent <= 0)
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break;
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}
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symtab++;
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}
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munmap(a_out_mmap, (size_t)st.st_size);
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return (nent);
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}
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#endif
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#ifdef _NLIST_DO_ELF
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static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int);
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/*
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* __elf_is_okay__ - Determine if ehdr really
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* is ELF and valid for the target platform.
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*
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* WARNING: This is NOT an ELF ABI function and
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* as such its use should be restricted.
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*/
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int
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__elf_is_okay__(Elf_Ehdr *ehdr)
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{
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int retval = 0;
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/*
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* We need to check magic, class size, endianess,
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* and version before we look at the rest of the
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* Elf_Ehdr structure. These few elements are
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* represented in a machine independant fashion.
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*/
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if (IS_ELF(*ehdr) &&
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ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
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ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
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ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
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/* Now check the machine dependant header */
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if (ehdr->e_machine == ELF_TARG_MACH &&
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ehdr->e_version == ELF_TARG_VER)
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retval = 1;
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}
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return retval;
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}
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int
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__elf_fdnlist(fd, list)
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int fd;
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struct nlist *list;
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{
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struct nlist *p;
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Elf_Off symoff = 0, symstroff = 0;
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Elf_Size symsize = 0, symstrsize = 0;
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Elf_Ssize cc, i;
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int nent = -1;
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int errsave;
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Elf_Sym sbuf[1024];
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Elf_Sym *s;
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Elf_Ehdr ehdr;
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char *strtab = NULL;
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Elf_Shdr *shdr = NULL;
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Elf_Size shdr_size;
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void *base;
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struct stat st;
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/* Make sure obj is OK */
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if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
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_read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
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!__elf_is_okay__(&ehdr) ||
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_fstat(fd, &st) < 0)
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return (-1);
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/* calculate section header table size */
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shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
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/* Make sure it's not too big to mmap */
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if (shdr_size > SIZE_T_MAX) {
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errno = EFBIG;
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return (-1);
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}
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/* mmap section header table */
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base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd,
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(off_t)ehdr.e_shoff);
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if (base == MAP_FAILED)
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return (-1);
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shdr = (Elf_Shdr *)base;
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/*
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* Find the symbol table entry and it's corresponding
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* string table entry. Version 1.1 of the ABI states
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* that there is only one symbol table but that this
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* could change in the future.
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*/
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for (i = 0; i < ehdr.e_shnum; i++) {
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if (shdr[i].sh_type == SHT_SYMTAB) {
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symoff = shdr[i].sh_offset;
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symsize = shdr[i].sh_size;
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symstroff = shdr[shdr[i].sh_link].sh_offset;
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symstrsize = shdr[shdr[i].sh_link].sh_size;
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break;
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}
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}
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/* Check for files too large to mmap. */
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if (symstrsize > SIZE_T_MAX) {
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errno = EFBIG;
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goto done;
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}
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/*
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* Map string table into our address space. This gives us
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* an easy way to randomly access all the strings, without
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* making the memory allocation permanent as with malloc/free
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* (i.e., munmap will return it to the system).
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*/
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base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd,
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(off_t)symstroff);
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if (base == MAP_FAILED)
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goto done;
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strtab = (char *)base;
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/*
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* clean out any left-over information for all valid entries.
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* Type and value defined to be 0 if not found; historical
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* versions cleared other and desc as well. Also figure out
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* the largest string length so don't read any more of the
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* string table than we have to.
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*
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* XXX clearing anything other than n_type and n_value violates
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* the semantics given in the man page.
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*/
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nent = 0;
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for (p = list; !ISLAST(p); ++p) {
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p->n_type = 0;
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p->n_other = 0;
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p->n_desc = 0;
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p->n_value = 0;
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++nent;
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}
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/* Don't process any further if object is stripped. */
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if (symoff == 0)
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goto done;
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if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
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nent = -1;
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goto done;
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}
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while (symsize > 0 && nent > 0) {
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cc = MIN(symsize, sizeof(sbuf));
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if (_read(fd, sbuf, cc) != cc)
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break;
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symsize -= cc;
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for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
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char *name;
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struct nlist *p;
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name = strtab + s->st_name;
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if (name[0] == '\0')
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continue;
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for (p = list; !ISLAST(p); p++) {
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if ((p->n_un.n_name[0] == '_' &&
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strcmp(name, p->n_un.n_name+1) == 0)
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|| strcmp(name, p->n_un.n_name) == 0) {
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elf_sym_to_nlist(p, s, shdr,
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ehdr.e_shnum);
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if (--nent <= 0)
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break;
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}
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}
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}
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}
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done:
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errsave = errno;
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if (strtab != NULL)
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munmap(strtab, symstrsize);
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if (shdr != NULL)
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munmap(shdr, shdr_size);
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errno = errsave;
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return (nent);
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}
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/*
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* Convert an Elf_Sym into an nlist structure. This fills in only the
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* n_value and n_type members.
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*/
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static void
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elf_sym_to_nlist(nl, s, shdr, shnum)
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struct nlist *nl;
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Elf_Sym *s;
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Elf_Shdr *shdr;
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int shnum;
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{
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nl->n_value = s->st_value;
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switch (s->st_shndx) {
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case SHN_UNDEF:
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case SHN_COMMON:
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nl->n_type = N_UNDF;
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break;
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case SHN_ABS:
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nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
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N_FN : N_ABS;
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break;
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default:
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if (s->st_shndx >= shnum)
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nl->n_type = N_UNDF;
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else {
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Elf_Shdr *sh = shdr + s->st_shndx;
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nl->n_type = sh->sh_type == SHT_PROGBITS ?
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(sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
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(sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
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}
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break;
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}
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if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
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ELF_ST_BIND(s->st_info) == STB_WEAK)
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nl->n_type |= N_EXT;
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}
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#endif /* _NLIST_DO_ELF */
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