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authordjm@openbsd.org <djm@openbsd.org>2019-07-15 13:11:38 +0000
committerDamien Miller <djm@mindrot.org>2019-07-15 23:21:18 +1000
commite18a27eedccb024acb3cd9820b650a5dff323f01 (patch)
tree8b7c4d8e03e092fc296cf3c899e4ce907dc31556
parentbc551dfebb55845537b1095cf3ccd01640a147b7 (diff)
upstream: two more bounds-checking sshbuf counterparts to common
string operations: sshbuf_cmp() (bcmp-like) and sshbuf_find() (memmem like) feedback and ok markus@ OpenBSD-Commit-ID: fd071ec2485c7198074a168ff363a0d6052a706a
-rw-r--r--sshbuf-misc.c39
-rw-r--r--sshbuf.h29
2 files changed, 66 insertions, 2 deletions
diff --git a/sshbuf-misc.c b/sshbuf-misc.c
index a077a01e..83b59810 100644
--- a/sshbuf-misc.c
+++ b/sshbuf-misc.c
@@ -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;
+}
diff --git a/sshbuf.h b/sshbuf.h
index 1d9d5bb2..79700b54 100644
--- a/sshbuf.h
+++ b/sshbuf.h
@@ -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
*
@@ -257,6 +257,33 @@ char *sshbuf_dtob64(struct sshbuf *buf);
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
* nul character.