freebsd-dev/lib/libkvm/kvm.c
Enji Cooper 0f5425a4fc kvm_write: fix -Wcast-qual warning in pointer arithmetic argument
Cast buf to `const char *` when doing arithmetic operation to match
`cp`'s type [1].

Differential Revision:	D10082
MFC after:	1 week
Reviewed by:	cem (earlier diff), vangyzen
Submitted by:	cem [1]
Sponsored by:	Dell EMC Isilon
2017-03-21 20:48:36 +00:00

490 lines
11 KiB
C

/*-
* Copyright (c) 1989, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software developed by the Computer Systems
* Engineering group at Lawrence Berkeley Laboratory under DARPA contract
* BG 91-66 and contributed to Berkeley.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)kvm.c 8.2 (Berkeley) 2/13/94";
#endif
#endif /* LIBC_SCCS and not lint */
#include <sys/param.h>
#include <sys/fnv_hash.h>
#define _WANT_VNET
#include <sys/user.h>
#include <sys/linker.h>
#include <sys/pcpu.h>
#include <sys/stat.h>
#include <net/vnet.h>
#include <fcntl.h>
#include <kvm.h>
#include <limits.h>
#include <paths.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "kvm_private.h"
SET_DECLARE(kvm_arch, struct kvm_arch);
static char _kd_is_null[] = "";
char *
kvm_geterr(kvm_t *kd)
{
if (kd == NULL)
return (_kd_is_null);
return (kd->errbuf);
}
static int
_kvm_read_kernel_ehdr(kvm_t *kd)
{
Elf *elf;
if (elf_version(EV_CURRENT) == EV_NONE) {
_kvm_err(kd, kd->program, "Unsupported libelf");
return (-1);
}
elf = elf_begin(kd->nlfd, ELF_C_READ, NULL);
if (elf == NULL) {
_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
return (-1);
}
if (elf_kind(elf) != ELF_K_ELF) {
_kvm_err(kd, kd->program, "kernel is not an ELF file");
return (-1);
}
if (gelf_getehdr(elf, &kd->nlehdr) == NULL) {
_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
elf_end(elf);
return (-1);
}
elf_end(elf);
switch (kd->nlehdr.e_ident[EI_DATA]) {
case ELFDATA2LSB:
case ELFDATA2MSB:
return (0);
default:
_kvm_err(kd, kd->program,
"unsupported ELF data encoding for kernel");
return (-1);
}
}
static kvm_t *
_kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout)
{
struct kvm_arch **parch;
struct stat st;
kd->vmfd = -1;
kd->pmfd = -1;
kd->nlfd = -1;
kd->vmst = NULL;
kd->procbase = NULL;
kd->argspc = NULL;
kd->argv = NULL;
if (uf == NULL)
uf = getbootfile();
else if (strlen(uf) >= MAXPATHLEN) {
_kvm_err(kd, kd->program, "exec file name too long");
goto failed;
}
if (flag & ~O_RDWR) {
_kvm_err(kd, kd->program, "bad flags arg");
goto failed;
}
if (mf == NULL)
mf = _PATH_MEM;
if ((kd->pmfd = open(mf, flag | O_CLOEXEC, 0)) < 0) {
_kvm_syserr(kd, kd->program, "%s", mf);
goto failed;
}
if (fstat(kd->pmfd, &st) < 0) {
_kvm_syserr(kd, kd->program, "%s", mf);
goto failed;
}
if (S_ISREG(st.st_mode) && st.st_size <= 0) {
errno = EINVAL;
_kvm_syserr(kd, kd->program, "empty file");
goto failed;
}
if (S_ISCHR(st.st_mode)) {
/*
* If this is a character special device, then check that
* it's /dev/mem. If so, open kmem too. (Maybe we should
* make it work for either /dev/mem or /dev/kmem -- in either
* case you're working with a live kernel.)
*/
if (strcmp(mf, _PATH_DEVNULL) == 0) {
kd->vmfd = open(_PATH_DEVNULL, O_RDONLY | O_CLOEXEC);
return (kd);
} else if (strcmp(mf, _PATH_MEM) == 0) {
if ((kd->vmfd = open(_PATH_KMEM, flag | O_CLOEXEC)) <
0) {
_kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
goto failed;
}
return (kd);
}
}
/*
* This is either a crash dump or a remote live system with its physical
* memory fully accessible via a special device.
* Open the namelist fd and determine the architecture.
*/
if ((kd->nlfd = open(uf, O_RDONLY | O_CLOEXEC, 0)) < 0) {
_kvm_syserr(kd, kd->program, "%s", uf);
goto failed;
}
if (_kvm_read_kernel_ehdr(kd) < 0)
goto failed;
if (strncmp(mf, _PATH_FWMEM, strlen(_PATH_FWMEM)) == 0 ||
strncmp(mf, _PATH_DEVVMM, strlen(_PATH_DEVVMM)) == 0) {
kd->rawdump = 1;
kd->writable = 1;
}
SET_FOREACH(parch, kvm_arch) {
if ((*parch)->ka_probe(kd)) {
kd->arch = *parch;
break;
}
}
if (kd->arch == NULL) {
_kvm_err(kd, kd->program, "unsupported architecture");
goto failed;
}
/*
* Non-native kernels require a symbol resolver.
*/
if (!kd->arch->ka_native(kd) && kd->resolve_symbol == NULL) {
_kvm_err(kd, kd->program,
"non-native kernel requires a symbol resolver");
goto failed;
}
/*
* Initialize the virtual address translation machinery.
*/
if (kd->arch->ka_initvtop(kd) < 0)
goto failed;
return (kd);
failed:
/*
* Copy out the error if doing sane error semantics.
*/
if (errout != NULL)
strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
(void)kvm_close(kd);
return (NULL);
}
kvm_t *
kvm_openfiles(const char *uf, const char *mf, const char *sf __unused, int flag,
char *errout)
{
kvm_t *kd;
if ((kd = calloc(1, sizeof(*kd))) == NULL) {
if (errout != NULL)
(void)strlcpy(errout, strerror(errno),
_POSIX2_LINE_MAX);
return (NULL);
}
return (_kvm_open(kd, uf, mf, flag, errout));
}
kvm_t *
kvm_open(const char *uf, const char *mf, const char *sf __unused, int flag,
const char *errstr)
{
kvm_t *kd;
if ((kd = calloc(1, sizeof(*kd))) == NULL) {
if (errstr != NULL)
(void)fprintf(stderr, "%s: %s\n",
errstr, strerror(errno));
return (NULL);
}
kd->program = errstr;
return (_kvm_open(kd, uf, mf, flag, NULL));
}
kvm_t *
kvm_open2(const char *uf, const char *mf, int flag, char *errout,
int (*resolver)(const char *, kvaddr_t *))
{
kvm_t *kd;
if ((kd = calloc(1, sizeof(*kd))) == NULL) {
if (errout != NULL)
(void)strlcpy(errout, strerror(errno),
_POSIX2_LINE_MAX);
return (NULL);
}
kd->resolve_symbol = resolver;
return (_kvm_open(kd, uf, mf, flag, errout));
}
int
kvm_close(kvm_t *kd)
{
int error = 0;
if (kd == NULL) {
errno = EINVAL;
return (-1);
}
if (kd->vmst != NULL)
kd->arch->ka_freevtop(kd);
if (kd->pmfd >= 0)
error |= close(kd->pmfd);
if (kd->vmfd >= 0)
error |= close(kd->vmfd);
if (kd->nlfd >= 0)
error |= close(kd->nlfd);
if (kd->procbase != 0)
free((void *)kd->procbase);
if (kd->argbuf != 0)
free((void *) kd->argbuf);
if (kd->argspc != 0)
free((void *) kd->argspc);
if (kd->argv != 0)
free((void *)kd->argv);
if (kd->pt_map != NULL)
free(kd->pt_map);
free((void *)kd);
return (error);
}
int
kvm_nlist2(kvm_t *kd, struct kvm_nlist *nl)
{
/*
* If called via the public interface, permit initialization of
* further virtualized modules on demand.
*/
return (_kvm_nlist(kd, nl, 1));
}
int
kvm_nlist(kvm_t *kd, struct nlist *nl)
{
struct kvm_nlist *kl;
int count, i, nfail;
/*
* Avoid reporting truncated addresses by failing for non-native
* cores.
*/
if (!kvm_native(kd)) {
_kvm_err(kd, kd->program, "kvm_nlist of non-native vmcore");
return (-1);
}
for (count = 0; nl[count].n_name != NULL && nl[count].n_name[0] != '\0';
count++)
;
if (count == 0)
return (0);
kl = calloc(count + 1, sizeof(*kl));
for (i = 0; i < count; i++)
kl[i].n_name = nl[i].n_name;
nfail = kvm_nlist2(kd, kl);
for (i = 0; i < count; i++) {
nl[i].n_type = kl[i].n_type;
nl[i].n_other = 0;
nl[i].n_desc = 0;
nl[i].n_value = kl[i].n_value;
}
return (nfail);
}
ssize_t
kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
{
return (kvm_read2(kd, kva, buf, len));
}
ssize_t
kvm_read2(kvm_t *kd, kvaddr_t kva, void *buf, size_t len)
{
int cc;
ssize_t cr;
off_t pa;
char *cp;
if (ISALIVE(kd)) {
/*
* We're using /dev/kmem. Just read straight from the
* device and let the active kernel do the address translation.
*/
errno = 0;
if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
_kvm_err(kd, 0, "invalid address (0x%jx)",
(uintmax_t)kva);
return (-1);
}
cr = read(kd->vmfd, buf, len);
if (cr < 0) {
_kvm_syserr(kd, 0, "kvm_read");
return (-1);
} else if (cr < (ssize_t)len)
_kvm_err(kd, kd->program, "short read");
return (cr);
}
cp = buf;
while (len > 0) {
cc = kd->arch->ka_kvatop(kd, kva, &pa);
if (cc == 0)
return (-1);
if (cc > (ssize_t)len)
cc = len;
errno = 0;
if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
_kvm_syserr(kd, 0, _PATH_MEM);
break;
}
cr = read(kd->pmfd, cp, cc);
if (cr < 0) {
_kvm_syserr(kd, kd->program, "kvm_read");
break;
}
/*
* If ka_kvatop returns a bogus value or our core file is
* truncated, we might wind up seeking beyond the end of the
* core file in which case the read will return 0 (EOF).
*/
if (cr == 0)
break;
cp += cr;
kva += cr;
len -= cr;
}
return (cp - (char *)buf);
}
ssize_t
kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
{
int cc;
ssize_t cw;
off_t pa;
const char *cp;
if (!ISALIVE(kd) && !kd->writable) {
_kvm_err(kd, kd->program,
"kvm_write not implemented for dead kernels");
return (-1);
}
if (ISALIVE(kd)) {
/*
* Just like kvm_read, only we write.
*/
errno = 0;
if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
_kvm_err(kd, 0, "invalid address (%lx)", kva);
return (-1);
}
cc = write(kd->vmfd, buf, len);
if (cc < 0) {
_kvm_syserr(kd, 0, "kvm_write");
return (-1);
} else if ((size_t)cc < len)
_kvm_err(kd, kd->program, "short write");
return (cc);
}
cp = buf;
while (len > 0) {
cc = kd->arch->ka_kvatop(kd, kva, &pa);
if (cc == 0)
return (-1);
if (cc > (ssize_t)len)
cc = len;
errno = 0;
if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
_kvm_syserr(kd, 0, _PATH_MEM);
break;
}
cw = write(kd->pmfd, cp, cc);
if (cw < 0) {
_kvm_syserr(kd, kd->program, "kvm_write");
break;
}
/*
* If ka_kvatop returns a bogus value or our core file is
* truncated, we might wind up seeking beyond the end of the
* core file in which case the read will return 0 (EOF).
*/
if (cw == 0)
break;
cp += cw;
kva += cw;
len -= cw;
}
return (cp - (const char *)buf);
}
int
kvm_native(kvm_t *kd)
{
if (ISALIVE(kd))
return (1);
return (kd->arch->ka_native(kd));
}