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upstream: add some functions to perform random-access read/write 

operations inside buffers with bounds checking. Intended to replace manual
pointer arithmetic wherever possible.

feedback and ok markus@

OpenBSD-Commit-ID: 91771fde7732738f1ffed078aa5d3bee6d198409
This commit is contained in:
djm@openbsd.org 2019-07-14 23:32:27 +00:00 committed by Damien Miller
parent 7250879c72
commit 101d164723
2 changed files with 183 additions and 3 deletions
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163
sshbuf-getput-basic.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: sshbuf-getput-basic.c,v 1.7 2017/06/01 04:51:58 djm Exp $ */
/* $OpenBSD: sshbuf-getput-basic.c,v 1.8 2019/07/14 23:32:27 djm Exp $ */
/*
* Copyright (c) 2011 Damien Miller
*
@ -93,6 +93,93 @@ sshbuf_get_u8(struct sshbuf *buf, u_char *valp)
return 0;
}
static int
check_offset(const struct sshbuf *buf, int wr, size_t offset, size_t len)
{
if (sshbuf_ptr(buf) == NULL) /* calls sshbuf_check_sanity() */
return SSH_ERR_INTERNAL_ERROR;
if (offset >= SIZE_MAX - len)
return SSH_ERR_INVALID_ARGUMENT;
if (offset + len > sshbuf_len(buf)) {
return wr ?
SSH_ERR_NO_BUFFER_SPACE : SSH_ERR_MESSAGE_INCOMPLETE;
}
return 0;
}
static int
check_roffset(const struct sshbuf *buf, size_t offset, size_t len,
const u_char **p)
{
int r;
*p = NULL;
if ((r = check_offset(buf, 0, offset, len)) != 0)
return r;
*p = sshbuf_ptr(buf) + offset;
return 0;
}
int
sshbuf_peek_u64(const struct sshbuf *buf, size_t offset, u_int64_t *valp)
{
const u_char *p = NULL;
int r;
if (valp != NULL)
*valp = 0;
if ((r = check_roffset(buf, offset, 8, &p)) != 0)
return r;
if (valp != NULL)
*valp = PEEK_U64(p);
return 0;
}
int
sshbuf_peek_u32(const struct sshbuf *buf, size_t offset, u_int32_t *valp)
{
const u_char *p = NULL;
int r;
if (valp != NULL)
*valp = 0;
if ((r = check_roffset(buf, offset, 4, &p)) != 0)
return r;
if (valp != NULL)
*valp = PEEK_U32(p);
return 0;
}
int
sshbuf_peek_u16(const struct sshbuf *buf, size_t offset, u_int16_t *valp)
{
const u_char *p = NULL;
int r;
if (valp != NULL)
*valp = 0;
if ((r = check_roffset(buf, offset, 2, &p)) != 0)
return r;
if (valp != NULL)
*valp = PEEK_U16(p);
return 0;
}
int
sshbuf_peek_u8(const struct sshbuf *buf, size_t offset, u_char *valp)
{
const u_char *p = NULL;
int r;
if (valp != NULL)
*valp = 0;
if ((r = check_roffset(buf, offset, 1, &p)) != 0)
return r;
if (valp != NULL)
*valp = *p;
return 0;
}
int
sshbuf_get_string(struct sshbuf *buf, u_char **valp, size_t *lenp)
{
@ -344,6 +431,80 @@ sshbuf_put_u8(struct sshbuf *buf, u_char val)
return 0;
}
static int
check_woffset(struct sshbuf *buf, size_t offset, size_t len, u_char **p)
{
int r;
*p = NULL;
if ((r = check_offset(buf, 1, offset, len)) != 0)
return r;
if (sshbuf_mutable_ptr(buf) == NULL)
return SSH_ERR_BUFFER_READ_ONLY;
*p = sshbuf_mutable_ptr(buf) + offset;
return 0;
}
int
sshbuf_poke_u64(struct sshbuf *buf, size_t offset, u_int64_t val)
{
u_char *p = NULL;
int r;
if ((r = check_woffset(buf, offset, 8, &p)) != 0)
return r;
POKE_U64(p, val);
return 0;
}
int
sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val)
{
u_char *p = NULL;
int r;
if ((r = check_woffset(buf, offset, 4, &p)) != 0)
return r;
POKE_U32(p, val);
return 0;
}
int
sshbuf_poke_u16(struct sshbuf *buf, size_t offset, u_int16_t val)
{
u_char *p = NULL;
int r;
if ((r = check_woffset(buf, offset, 2, &p)) != 0)
return r;
POKE_U16(p, val);
return 0;
}
int
sshbuf_poke_u8(struct sshbuf *buf, size_t offset, u_char val)
{
u_char *p = NULL;
int r;
if ((r = check_woffset(buf, offset, 1, &p)) != 0)
return r;
*p = val;
return 0;
}
int
sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len)
{
u_char *p = NULL;
int r;
if ((r = check_woffset(buf, offset, len, &p)) != 0)
return r;
memcpy(p, v, len);
return 0;
}
int
sshbuf_put_string(struct sshbuf *buf, const void *v, size_t len)
{

23
sshbuf.h
View File

@ -1,4 +1,4 @@
/* $OpenBSD: sshbuf.h,v 1.13 2019/01/21 09:54:11 djm Exp $ */
/* $OpenBSD: sshbuf.h,v 1.14 2019/07/14 23:32:27 djm Exp $ */
/*
* Copyright (c) 2011 Damien Miller
*
@ -176,6 +176,26 @@ int sshbuf_put_u32(struct sshbuf *buf, u_int32_t val);
int sshbuf_put_u16(struct sshbuf *buf, u_int16_t val);
int sshbuf_put_u8(struct sshbuf *buf, u_char val);
/* Functions to peek at the contents of a buffer without modifying it. */
int sshbuf_peek_u64(const struct sshbuf *buf, size_t offset,
u_int64_t *valp);
int sshbuf_peek_u32(const struct sshbuf *buf, size_t offset,
u_int32_t *valp);
int sshbuf_peek_u16(const struct sshbuf *buf, size_t offset,
u_int16_t *valp);
int sshbuf_peek_u8(const struct sshbuf *buf, size_t offset,
u_char *valp);
/*
* Functions to poke values into an exisiting buffer (e.g. a length header
* to a packet). The destination bytes must already exist in the buffer.
*/
int sshbuf_poke_u64(struct sshbuf *buf, size_t offset, u_int64_t val);
int sshbuf_poke_u32(struct sshbuf *buf, size_t offset, u_int32_t val);
int sshbuf_poke_u16(struct sshbuf *buf, size_t offset, u_int16_t val);
int sshbuf_poke_u8(struct sshbuf *buf, size_t offset, u_char val);
int sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len);
/*
* Functions to extract or store SSH wire encoded strings (u32 len || data)
* The "cstring" variants admit no \0 characters in the string contents.
@ -202,7 +222,6 @@ int sshbuf_get_string_direct(struct sshbuf *buf, const u_char **valp,
/* Another variant: "peeks" into the buffer without modifying it */
int sshbuf_peek_string_direct(const struct sshbuf *buf, const u_char **valp,
size_t *lenp);
/* XXX peek_u8 / peek_u32 */
/*
* Functions to extract or store SSH wire encoded bignums and elliptic