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upstream: adjust ftruncate() logic to handle servers that reorder 

requests.

sftp/scp will ftruncate the destination file after a transfer completes,
to deal with the case where a longer destination file already existed.
We tracked the highest contiguous block transferred to deal with this
case, but our naive tracking doesn't deal with servers that reorder
requests - a misfeature strictly permitted by the protocol but seldom
implemented.

Adjust the logic to ftruncate() at the highest absolute block received
when the transfer is successful. feedback deraadt@ ok markus@

prompted by https://github.com/openssh/openssh-portable/commit/9b733#commitcomment-110679778

OpenBSD-Commit-ID: 4af7fac75958ad8507b4fea58706f3ff0cfddb1b
This commit is contained in:
djm@openbsd.org 2023-04-30 22:54:22 +00:00 committed by Damien Miller
parent c8eb394175
commit aacfd67674
No known key found for this signature in database
1 changed files with 39 additions and 11 deletions
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50
sftp-client.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: sftp-client.c,v 1.170 2023/03/28 07:44:32 dtucker Exp $ */
/* $OpenBSD: sftp-client.c,v 1.171 2023/04/30 22:54:22 djm Exp $ */
/*
* Copyright (c) 2001-2004 Damien Miller <djm@openbsd.org>
*
@ -1600,7 +1600,7 @@ do_download(struct sftp_conn *conn, const char *remote_path,
u_char *handle;
int local_fd = -1, write_error;
int read_error, write_errno, lmodified = 0, reordered = 0, r;
u_int64_t offset = 0, size, highwater;
u_int64_t offset = 0, size, highwater = 0, maxack = 0;
u_int mode, id, buflen, num_req, max_req, status = SSH2_FX_OK;
off_t progress_counter;
size_t handle_len;
@ -1647,7 +1647,6 @@ do_download(struct sftp_conn *conn, const char *remote_path,
error("open local \"%s\": %s", local_path, strerror(errno));
goto fail;
}
offset = highwater = 0;
if (resume_flag) {
if (fstat(local_fd, &st) == -1) {
error("stat local \"%s\": %s",
@ -1668,7 +1667,7 @@ do_download(struct sftp_conn *conn, const char *remote_path,
close(local_fd);
return -1;
}
offset = highwater = st.st_size;
offset = highwater = maxack = st.st_size;
}
/* Read from remote and write to local */
@ -1750,11 +1749,21 @@ do_download(struct sftp_conn *conn, const char *remote_path,
write_errno = errno;
write_error = 1;
max_req = 0;
} else {
/*
* Track both the highest offset acknowledged
* and the highest *contiguous* offset
* acknowledged.
* We'll need the latter for ftruncate()ing
* interrupted transfers.
*/
if (maxack < req->offset + len)
maxack = req->offset + len;
if (!reordered && req->offset <= highwater)
highwater = maxack;
else if (!reordered && req->offset > highwater)
reordered = 1;
}
else if (!reordered && req->offset <= highwater)
highwater = req->offset + len;
else if (!reordered && req->offset > highwater)
reordered = 1;
progress_counter += len;
free(data);
@ -1803,12 +1812,19 @@ do_download(struct sftp_conn *conn, const char *remote_path,
/* Sanity check */
if (TAILQ_FIRST(&requests) != NULL)
fatal("Transfer complete, but requests still in queue");
if (!read_error && !write_error && !interrupted) {
/* we got everything */
highwater = maxack;
}
/*
* Truncate at highest contiguous point to avoid holes on interrupt,
* or unconditionally if writing in place.
*/
if (inplace_flag || read_error || write_error || interrupted) {
if (reordered && resume_flag) {
if (reordered && resume_flag &&
(read_error || write_error || interrupted)) {
error("Unable to resume download of \"%s\": "
"server reordered requests", local_path);
}
@ -2008,7 +2024,7 @@ do_upload(struct sftp_conn *conn, const char *local_path,
struct stat sb;
Attrib a, t, *c = NULL;
u_int32_t startid, ackid;
u_int64_t highwater = 0;
u_int64_t highwater = 0, maxack = 0;
struct request *ack = NULL;
struct requests acks;
size_t handle_len;
@ -2150,8 +2166,16 @@ do_upload(struct sftp_conn *conn, const char *local_path,
ack->id, ack->len, (unsigned long long)ack->offset);
++ackid;
progress_counter += ack->len;
/*
* Track both the highest offset acknowledged and the
* highest *contiguous* offset acknowledged.
* We'll need the latter for ftruncate()ing
* interrupted transfers.
*/
if (maxack < ack->offset + ack->len)
maxack = ack->offset + ack->len;
if (!reordered && ack->offset <= highwater)
highwater = ack->offset + ack->len;
highwater = maxack;
else if (!reordered && ack->offset > highwater) {
debug3_f("server reordered ACKs");
reordered = 1;
@ -2168,6 +2192,10 @@ do_upload(struct sftp_conn *conn, const char *local_path,
stop_progress_meter();
free(data);
if (status == SSH2_FX_OK && !interrupted) {
/* we got everything */
highwater = maxack;
}
if (status != SSH2_FX_OK) {
error("write remote \"%s\": %s", remote_path, fx2txt(status));
status = SSH2_FX_FAILURE;