Attachment 3344 Details for Bug 2948 – sftp server copy-data extension

[patch] sftp server copy-data extension

sftp-copy-data.patch (text/plain), 5.93 KB, created by Darren Tucker on 2019-12-23 09:49:50 AEDT

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Creator: Darren Tucker

Created: 2019-12-23 09:49:50 AEDT

Size: 5.93 KB

patch

obsolete

> PROTOCOL      | 39 ++++++++++++++++++++++-
> sftp-server.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 125 insertions(+), 1 deletion(-)
>
>diff --git a/PROTOCOL b/PROTOCOL
>index f75c1c0ae5b0..04a392db33be 100644
>--- a/PROTOCOL
>+++ b/PROTOCOL
>@@ -459,12 +459,49 @@ This request asks the server to call fsync(2) on an open file handle.
> 	string		"fsync@openssh.com"
> 	string		handle
> 
>-One receiving this request, a server will call fsync(handle_fd) and will
>+On receiving this request, a server will call fsync(handle_fd) and will
> respond with a SSH_FXP_STATUS message.
> 
> This extension is advertised in the SSH_FXP_VERSION hello with version
> "1".
> 
>+3.7. sftp: Extension request "copy-data"
>+
>+This request asks the server to copy data from one open file handle and
>+write it to a different open file handle.  This avoids needing to
>+download the data before uploading it across the network twice.
>+
>+	byte		SSH_FXP_EXTENDED
>+	uint32		id
>+	string		"copy-data"
>+	string		read-from-handle
>+	uint64		read-from-offset
>+	uint64		read-data-length
>+	string		write-to-handle
>+	uint64		write-to-offset
>+
>+The server will copy read-data-length bytes starting from
>+read-from-offset from the read-from-handle and write them to
>+write-to-handle starting from write-to-offset, and then respond with a
>+SSH_FXP_STATUS message.
>+
>+It's equivalent to issuing a series of SSH_FXP_READ requests on
>+read-from-handle and a series of requests of SSH_FXP_WRITE on
>+write-to-handle.
>+
>+If read-from-handle and write-to-handle are the same, the server will
>+fail the request and respond with a SSH_FX_INVALID_PARAMETER message.
>+
>+If read-data-length is 0, then the server will read data from the
>+read-from-handle until EOF is reached.
>+
>+This extension is advertised in the SSH_FXP_VERSION hello with version
>+"1".
>+
>+This request is identical to the "copy-data" request documented in:
>+
>+https://tools.ietf.org/html/draft-ietf-secsh-filexfer-extensions-00#section-7
>+
> 4. Miscellaneous changes
> 
> 4.1 Public key format
>diff --git a/sftp-server.c b/sftp-server.c
>index beac78ed0324..2d7c1c87e83f 100644
>--- a/sftp-server.c
>+++ b/sftp-server.c
>@@ -107,6 +107,7 @@ static void process_extended_statvfs(u_int32_t id);
> static void process_extended_fstatvfs(u_int32_t id);
> static void process_extended_hardlink(u_int32_t id);
> static void process_extended_fsync(u_int32_t id);
>+static void process_extended_copy_data(u_int32_t id);
> static void process_extended(u_int32_t id);
> 
> struct sftp_handler {
>@@ -148,6 +149,7 @@ static const struct sftp_handler extended_handlers[] = {
> 	{ "fstatvfs", "fstatvfs@openssh.com", 0, process_extended_fstatvfs, 0 },
> 	{ "hardlink", "hardlink@openssh.com", 0, process_extended_hardlink, 1 },
> 	{ "fsync", "fsync@openssh.com", 0, process_extended_fsync, 1 },
>+	{ "copy-data", "copy-data", 0, process_extended_copy_data, 1 },
> 	{ NULL, NULL, 0, NULL, 0 }
> };
> 
>@@ -666,6 +668,9 @@ process_init(void)
> 	    (r = sshbuf_put_cstring(msg, "1")) != 0 || /* version */
> 	    /* fsync extension */
> 	    (r = sshbuf_put_cstring(msg, "fsync@openssh.com")) != 0 ||
>+	    (r = sshbuf_put_cstring(msg, "1")) != 0 || /* version */
>+	    /* copy-data extension */
>+	    (r = sshbuf_put_cstring(msg, "copy-data")) != 0 ||
> 	    (r = sshbuf_put_cstring(msg, "1")) != 0) /* version */
> 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
> 	send_msg(msg);
>@@ -1369,6 +1374,88 @@ process_extended_fsync(u_int32_t id)
> 	send_status(id, status);
> }
> 
>+static void
>+process_extended_copy_data(u_int32_t id)
>+{
>+	u_char buf[64*1024];
>+	int read_handle, read_fd, write_handle, write_fd;
>+	u_int64_t len, read_off, read_len, write_off;
>+	int r, ret, copy_until_eof, status = SSH2_FX_OP_UNSUPPORTED;
>+
>+	if ((r = get_handle(iqueue, &read_handle)) != 0 ||
>+	    (r = sshbuf_get_u64(iqueue, &read_off)) != 0 ||
>+	    (r = sshbuf_get_u64(iqueue, &read_len)) != 0 ||
>+	    (r = get_handle(iqueue, &write_handle)) != 0 ||
>+	    (r = sshbuf_get_u64(iqueue, &write_off)) != 0)
>+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
>+
>+	debug("request %u: copy-data from \"%s\" (handle %d) off %llu len %llu "
>+	    "to \"%s\" (handle %d) off %llu",
>+	    id, handle_to_name(read_handle), read_handle,
>+	    (unsigned long long)read_off, (unsigned long long)read_len,
>+	    handle_to_name(write_handle), write_handle,
>+	    (unsigned long long)write_off);
>+
>+	/* For read length of 0, we read until EOF. */
>+	if (read_len == 0) {
>+		read_len = (u_int64_t)-1 - read_off;
>+		copy_until_eof = 1;
>+	} else
>+		copy_until_eof = 0;
>+
>+	read_fd = handle_to_fd(read_handle);
>+	write_fd = handle_to_fd(write_handle);
>+
>+	/* Disallow reading & writing to the same handle */
>+	if (read_handle == write_handle || read_fd < 0 || write_fd < 0) {
>+		status = SSH2_FX_FAILURE;
>+	} else {
>+		if (lseek(read_fd, read_off, SEEK_SET) < 0) {
>+			status = errno_to_portable(errno);
>+			error("process_extended_copy_data: read_seek failed");
>+		} else if (!(handle_to_flags(write_handle) & O_APPEND) &&
>+				lseek(write_fd, write_off, SEEK_SET) < 0) {
>+			status = errno_to_portable(errno);
>+			error("process_extended_copy_data: write_seek failed");
>+		} else {
>+			/* Process the request in chunks. */
>+			while (read_len || copy_until_eof) {
>+				len = MINIMUM(sizeof(buf), read_len);
>+				read_len -= len;
>+
>+				ret = read(read_fd, buf, len);
>+				if (ret < 0) {
>+					status = errno_to_portable(errno);
>+					break;
>+				} else if (ret == 0) {
>+					status = copy_until_eof ? SSH2_FX_OK : SSH2_FX_EOF;
>+					break;
>+				}
>+				len = ret;
>+				handle_update_read(read_handle, len);
>+
>+				ret = write(write_fd, buf, len);
>+				if (ret < 0) {
>+					status = errno_to_portable(errno);
>+					error("process_extended_copy_data: write failed");
>+					break;
>+				}
>+				handle_update_write(write_handle, len);
>+				if ((size_t)ret != len) {
>+					debug2("nothing at all written");
>+					status = SSH2_FX_FAILURE;
>+					break;
>+				}
>+			}
>+
>+			if (read_len == 0)
>+				status = SSH2_FX_OK;
>+		}
>+	}
>+
>+	send_status(id, status);
>+}
>+
> static void
> process_extended(u_int32_t id)
> {

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