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/* $OpenBSD: sshbuf.c,v 1.6 2016/01/12 23:42:54 djm Exp $ */
/*
* Copyright (c) 2011 Damien Miller
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#define SSHBUF_INTERNAL
#include "includes.h"
#include <sys/param.h> /* roundup */
#include <sys/types.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "ssherr.h"
#include "sshbuf.h"
static inline int
sshbuf_check_sanity(const struct sshbuf *buf)
{
SSHBUF_TELL("sanity");
if (__predict_false(buf == NULL ||
(!buf->readonly && buf->d != buf->cd) ||
buf->refcount < 1 || buf->refcount > SSHBUF_REFS_MAX ||
buf->cd == NULL ||
(buf->dont_free && (buf->readonly || buf->parent != NULL)) ||
buf->max_size > SSHBUF_SIZE_MAX ||
buf->alloc > buf->max_size ||
buf->size > buf->alloc ||
buf->off > buf->size)) {
/* Do not try to recover from corrupted buffer internals */
SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
signal(SIGSEGV, SIG_DFL);
raise(SIGSEGV);
return SSH_ERR_INTERNAL_ERROR;
}
return 0;
}
static void
sshbuf_maybe_pack(struct sshbuf *buf, int force)
{
SSHBUF_DBG(("force %d", force));
SSHBUF_TELL("pre-pack");
if (buf->off == 0 || buf->readonly || buf->refcount > 1)
return;
if (force ||
(buf->off >= SSHBUF_PACK_MIN && buf->off >= buf->size / 2)) {
memmove(buf->d, buf->d + buf->off, buf->size - buf->off);
buf->size -= buf->off;
buf->off = 0;
SSHBUF_TELL("packed");
}
}
struct sshbuf *
sshbuf_new(void)
{
struct sshbuf *ret;
if ((ret = calloc(sizeof(*ret), 1)) == NULL)
return NULL;
ret->alloc = SSHBUF_SIZE_INIT;
ret->max_size = SSHBUF_SIZE_MAX;
ret->readonly = 0;
ret->refcount = 1;
ret->parent = NULL;
if ((ret->cd = ret->d = calloc(1, ret->alloc)) == NULL) {
free(ret);
return NULL;
}
return ret;
}
struct sshbuf *
sshbuf_from(const void *blob, size_t len)
{
struct sshbuf *ret;
if (blob == NULL || len > SSHBUF_SIZE_MAX ||
(ret = calloc(sizeof(*ret), 1)) == NULL)
return NULL;
ret->alloc = ret->size = ret->max_size = len;
ret->readonly = 1;
ret->refcount = 1;
ret->parent = NULL;
ret->cd = blob;
ret->d = NULL;
return ret;
}
int
sshbuf_set_parent(struct sshbuf *child, struct sshbuf *parent)
{
int r;
if ((r = sshbuf_check_sanity(child)) != 0 ||
(r = sshbuf_check_sanity(parent)) != 0)
return r;
child->parent = parent;
child->parent->refcount++;
return 0;
}
struct sshbuf *
sshbuf_fromb(struct sshbuf *buf)
{
struct sshbuf *ret;
if (sshbuf_check_sanity(buf) != 0)
return NULL;
if ((ret = sshbuf_from(sshbuf_ptr(buf), sshbuf_len(buf))) == NULL)
return NULL;
if (sshbuf_set_parent(ret, buf) != 0) {
sshbuf_free(ret);
return NULL;
}
return ret;
}
void
sshbuf_init(struct sshbuf *ret)
{
explicit_bzero(ret, sizeof(*ret));
ret->alloc = SSHBUF_SIZE_INIT;
ret->max_size = SSHBUF_SIZE_MAX;
ret->readonly = 0;
ret->dont_free = 1;
ret->refcount = 1;
if ((ret->cd = ret->d = calloc(1, ret->alloc)) == NULL)
ret->alloc = 0;
}
void
sshbuf_free(struct sshbuf *buf)
{
int dont_free = 0;
if (buf == NULL)
return;
/*
* The following will leak on insane buffers, but this is the safest
* course of action - an invalid pointer or already-freed pointer may
* have been passed to us and continuing to scribble over memory would
* be bad.
*/
if (sshbuf_check_sanity(buf) != 0)
return;
/*
* If we are a child, the free our parent to decrement its reference
* count and possibly free it.
*/
sshbuf_free(buf->parent);
buf->parent = NULL;
/*
* If we are a parent with still-extant children, then don't free just
* yet. The last child's call to sshbuf_free should decrement our
* refcount to 0 and trigger the actual free.
*/
buf->refcount--;
if (buf->refcount > 0)
return;
dont_free = buf->dont_free;
if (!buf->readonly) {
explicit_bzero(buf->d, buf->alloc);
free(buf->d);
}
explicit_bzero(buf, sizeof(*buf));
if (!dont_free)
free(buf);
}
void
sshbuf_reset(struct sshbuf *buf)
{
u_char *d;
if (buf->readonly || buf->refcount > 1) {
/* Nonsensical. Just make buffer appear empty */
buf->off = buf->size;
return;
}
if (sshbuf_check_sanity(buf) == 0)
explicit_bzero(buf->d, buf->alloc);
buf->off = buf->size = 0;
if (buf->alloc != SSHBUF_SIZE_INIT) {
if ((d = realloc(buf->d, SSHBUF_SIZE_INIT)) != NULL) {
buf->cd = buf->d = d;
buf->alloc = SSHBUF_SIZE_INIT;
}
}
}
size_t
sshbuf_max_size(const struct sshbuf *buf)
{
return buf->max_size;
}
size_t
sshbuf_alloc(const struct sshbuf *buf)
{
return buf->alloc;
}
const struct sshbuf *
sshbuf_parent(const struct sshbuf *buf)
{
return buf->parent;
}
u_int
sshbuf_refcount(const struct sshbuf *buf)
{
return buf->refcount;
}
int
sshbuf_set_max_size(struct sshbuf *buf, size_t max_size)
{
size_t rlen;
u_char *dp;
int r;
SSHBUF_DBG(("set max buf = %p len = %zu", buf, max_size));
if ((r = sshbuf_check_sanity(buf)) != 0)
return r;
if (max_size == buf->max_size)
return 0;
if (buf->readonly || buf->refcount > 1)
return SSH_ERR_BUFFER_READ_ONLY;
if (max_size > SSHBUF_SIZE_MAX)
return SSH_ERR_NO_BUFFER_SPACE;
/* pack and realloc if necessary */
sshbuf_maybe_pack(buf, max_size < buf->size);
if (max_size < buf->alloc && max_size > buf->size) {
if (buf->size < SSHBUF_SIZE_INIT)
rlen = SSHBUF_SIZE_INIT;
else
rlen = roundup(buf->size, SSHBUF_SIZE_INC);
if (rlen > max_size)
rlen = max_size;
explicit_bzero(buf->d + buf->size, buf->alloc - buf->size);
SSHBUF_DBG(("new alloc = %zu", rlen));
if ((dp = realloc(buf->d, rlen)) == NULL)
return SSH_ERR_ALLOC_FAIL;
buf->cd = buf->d = dp;
buf->alloc = rlen;
}
SSHBUF_TELL("new-max");
if (max_size < buf->alloc)
return SSH_ERR_NO_BUFFER_SPACE;
buf->max_size = max_size;
return 0;
}
size_t
sshbuf_len(const struct sshbuf *buf)
{
if (sshbuf_check_sanity(buf) != 0)
return 0;
return buf->size - buf->off;
}
size_t
sshbuf_avail(const struct sshbuf *buf)
{
if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1)
return 0;
return buf->max_size - (buf->size - buf->off);
}
const u_char *
sshbuf_ptr(const struct sshbuf *buf)
{
if (sshbuf_check_sanity(buf) != 0)
return NULL;
return buf->cd + buf->off;
}
u_char *
sshbuf_mutable_ptr(const struct sshbuf *buf)
{
if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1)
return NULL;
return buf->d + buf->off;
}
int
sshbuf_check_reserve(const struct sshbuf *buf, size_t len)
{
int r;
if ((r = sshbuf_check_sanity(buf)) != 0)
return r;
if (buf->readonly || buf->refcount > 1)
return SSH_ERR_BUFFER_READ_ONLY;
SSHBUF_TELL("check");
/* Check that len is reasonable and that max_size + available < len */
if (len > buf->max_size || buf->max_size - len < buf->size - buf->off)
return SSH_ERR_NO_BUFFER_SPACE;
return 0;
}
int
sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp)
{
size_t rlen, need;
u_char *dp;
int r;
if (dpp != NULL)
*dpp = NULL;
SSHBUF_DBG(("reserve buf = %p len = %zu", buf, len));
if ((r = sshbuf_check_reserve(buf, len)) != 0)
return r;
/*
* If the requested allocation appended would push us past max_size
* then pack the buffer, zeroing buf->off.
*/
sshbuf_maybe_pack(buf, buf->size + len > buf->max_size);
SSHBUF_TELL("reserve");
if (len + buf->size > buf->alloc) {
/*
* Prefer to alloc in SSHBUF_SIZE_INC units, but
* allocate less if doing so would overflow max_size.
*/
need = len + buf->size - buf->alloc;
rlen = roundup(buf->alloc + need, SSHBUF_SIZE_INC);
SSHBUF_DBG(("need %zu initial rlen %zu", need, rlen));
if (rlen > buf->max_size)
rlen = buf->alloc + need;
SSHBUF_DBG(("adjusted rlen %zu", rlen));
if ((dp = realloc(buf->d, rlen)) == NULL) {
SSHBUF_DBG(("realloc fail"));
if (dpp != NULL)
*dpp = NULL;
return SSH_ERR_ALLOC_FAIL;
}
buf->alloc = rlen;
buf->cd = buf->d = dp;
if ((r = sshbuf_check_reserve(buf, len)) < 0) {
/* shouldn't fail */
if (dpp != NULL)
*dpp = NULL;
return r;
}
}
dp = buf->d + buf->size;
buf->size += len;
SSHBUF_TELL("done");
if (dpp != NULL)
*dpp = dp;
return 0;
}
int
sshbuf_consume(struct sshbuf *buf, size_t len)
{
int r;
SSHBUF_DBG(("len = %zu", len));
if ((r = sshbuf_check_sanity(buf)) != 0)
return r;
if (len == 0)
return 0;
if (len > sshbuf_len(buf))
return SSH_ERR_MESSAGE_INCOMPLETE;
buf->off += len;
SSHBUF_TELL("done");
return 0;
}
int
sshbuf_consume_end(struct sshbuf *buf, size_t len)
{
int r;
SSHBUF_DBG(("len = %zu", len));
if ((r = sshbuf_check_sanity(buf)) != 0)
return r;
if (len == 0)
return 0;
if (len > sshbuf_len(buf))
return SSH_ERR_MESSAGE_INCOMPLETE;
buf->size -= len;
SSHBUF_TELL("done");
return 0;
}