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upstream: two more bounds-checking sshbuf counterparts to common

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string operations: sshbuf_cmp() (bcmp-like) and sshbuf_find() (memmem like)

feedback and ok markus@

OpenBSD-Commit-ID: fd071ec2485c7198074a168ff363a0d6052a706a
This commit is contained in:
djm@openbsd.org 2019-07-15 13:11:38 +00:00 committed by Damien Miller
parent bc551dfebb
commit e18a27eedc
2 changed files with 66 additions and 2 deletions
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39
sshbuf-misc.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: sshbuf-misc.c,v 1.7 2019/07/07 01:05:00 dtucker Exp $ */
/* $OpenBSD: sshbuf-misc.c,v 1.8 2019/07/15 13:11:38 djm Exp $ */
/*
* Copyright (c) 2011 Damien Miller
*
@ -158,3 +158,40 @@ sshbuf_dup_string(struct sshbuf *buf)
return r;
}
int
sshbuf_cmp(const struct sshbuf *b, size_t offset,
const u_char *s, size_t len)
{
if (sshbuf_ptr(b) == NULL)
return SSH_ERR_INTERNAL_ERROR;
if (offset > SSHBUF_SIZE_MAX || len > SSHBUF_SIZE_MAX || len == 0)
return SSH_ERR_INVALID_ARGUMENT;
if (offset + len > sshbuf_len(b))
return SSH_ERR_MESSAGE_INCOMPLETE;
if (timingsafe_bcmp(sshbuf_ptr(b) + offset, s, len) != 0)
return SSH_ERR_INVALID_FORMAT;
return 0;
}
int
sshbuf_find(const struct sshbuf *b, size_t start_offset,
const u_char *s, size_t len, size_t *offsetp)
{
void *p;
if (offsetp != NULL)
*offsetp = 0;
if (sshbuf_ptr(b) == NULL)
return SSH_ERR_INTERNAL_ERROR;
if (start_offset > SSHBUF_SIZE_MAX || len > SSHBUF_SIZE_MAX || len == 0)
return SSH_ERR_INVALID_ARGUMENT;
if (start_offset > sshbuf_len(b) || start_offset + len > sshbuf_len(b))
return SSH_ERR_MESSAGE_INCOMPLETE;
if ((p = memmem(sshbuf_ptr(b) + start_offset,
sshbuf_len(b) - start_offset, s, len)) == NULL)
return SSH_ERR_INVALID_FORMAT;
if (offsetp != NULL)
*offsetp = (const u_char *)p - sshbuf_ptr(b);
return 0;
}

29
sshbuf.h
View File

@ -1,4 +1,4 @@
/* $OpenBSD: sshbuf.h,v 1.14 2019/07/14 23:32:27 djm Exp $ */
/* $OpenBSD: sshbuf.h,v 1.15 2019/07/15 13:11:38 djm Exp $ */
/*
* Copyright (c) 2011 Damien Miller
*
@ -256,6 +256,33 @@ char *sshbuf_dtob64(struct sshbuf *buf);
/* Decode base64 data and append it to the buffer */
int sshbuf_b64tod(struct sshbuf *buf, const char *b64);
/*
* Tests whether the buffer contains the specified byte sequence at the
* specified offset. Returns 0 on successful match, or a ssherr.h code
* otherwise. SSH_ERR_INVALID_FORMAT indicates sufficient bytes were
* present but the buffer contents did not match those supplied. Zero-
* length comparisons are not allowed.
*
* If sufficient data is present to make a comparison, then it is
* performed with timing independent of the value of the data. If
* insufficient data is present then the comparison is not attempted at
* all.
*/
int sshbuf_cmp(const struct sshbuf *b, size_t offset,
const u_char *s, size_t len);
/*
* Searches the buffer for the specified string. Returns 0 on success
* and updates *offsetp with the offset of the first match, relative to
* the start of the buffer. Otherwise sshbuf_find will return a ssherr.h
* error code. SSH_ERR_INVALID_FORMAT indicates sufficient bytes were
* present in the buffer for a match to be possible but none was found.
* Searches for zero-length data are not allowed.
*/
int
sshbuf_find(const struct sshbuf *b, size_t start_offset,
const u_char *s, size_t len, size_t *offsetp);
/*
* Duplicate the contents of a buffer to a string (caller to free).
* Returns NULL on buffer error, or if the buffer contains a premature