Attachment 14671 Details for Bug 13688 – Possible patch for master

[patch] Possible patch for master

bug13688-wip.patch (text/plain), 3.77 KB, created by Ralph Böhme on 2018-11-21 09:30:20 UTC

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Creator: Ralph Böhme

Created: 2018-11-21 09:30:20 UTC

Size: 3.77 KB

patch

obsolete

>From f51f1cc825bbbee917c4c6a7a79c813a97d415ca Mon Sep 17 00:00:00 2001
>From: Ralph Boehme <slow@samba.org>
>Date: Mon, 19 Nov 2018 15:17:54 +0100
>Subject: [PATCH] vfs_shadow_copy2: nicely deal with attempts to open previous
> version for writing
>
>Bug: https://bugzilla.samba.org/show_bug.cgi?id=13688
>---
> source3/modules/vfs_shadow_copy2.c | 100 ++++++++++++++++++++++++++++-
> 1 file changed, 99 insertions(+), 1 deletion(-)
>
>diff --git a/source3/modules/vfs_shadow_copy2.c b/source3/modules/vfs_shadow_copy2.c
>index 79c1ee5cf33..cd83ee66587 100644
>--- a/source3/modules/vfs_shadow_copy2.c
>+++ b/source3/modules/vfs_shadow_copy2.c
>@@ -36,6 +36,8 @@
> #include "include/ntioctl.h"
> #include "util_tdb.h"
> #include "lib/util_path.h"
>+#include "libcli/security/security.h"
>+#include "lib/util/tevent_unix.h"
> 
> struct shadow_copy2_config {
> 	char *gmt_format;
>@@ -1367,7 +1369,13 @@ static int shadow_copy2_open(vfs_handle_struct *handle,
> 		return -1;
> 	}
> 
>-	ret = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
>+	/*
>+	 * Just pave over the user requested mode and use O_RDONLY. Later
>+	 * attempts by the client to write on the handle will fail in the
>+	 * pwrite() syscall with EINVAL which we carefully map to EROFS. In sum,
>+	 * this matches Windows behaviour.
>+	 */
>+	ret = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, O_RDONLY);
> 	if (ret == -1) {
> 		saved_errno = errno;
> 	}
>@@ -2855,6 +2863,96 @@ static int shadow_copy2_get_quota(vfs_handle_struct *handle,
> 	return ret;
> }
> 
>+static ssize_t shadow_copy2_pwrite(vfs_handle_struct *handle,
>+				   files_struct *fsp,
>+				   const void *data,
>+				   size_t n,
>+				   off_t offset)
>+{
>+	ssize_t nwritten;
>+
>+	nwritten = SMB_VFS_NEXT_PWRITE(handle, fsp, data, n, offset);
>+	if (nwritten == -1) {
>+		if (errno == EINVAL && fsp->can_write) {
>+			errno = EROFS;
>+		}
>+	}
>+
>+	return nwritten;
>+}
>+
>+struct shadow_copy2_pwrite_state {
>+	vfs_handle_struct *handle;
>+	files_struct *fsp;
>+	ssize_t ret;
>+	struct vfs_aio_state vfs_aio_state;
>+};
>+
>+static void shadow_copy2_pwrite_done(struct tevent_req *subreq);
>+
>+static struct tevent_req *shadow_copy2_pwrite_send(
>+	struct vfs_handle_struct *handle, TALLOC_CTX *mem_ctx,
>+	struct tevent_context *ev, struct files_struct *fsp,
>+	const void *data, size_t n, off_t offset)
>+{
>+	struct tevent_req *req = NULL, *subreq = NULL;
>+	struct shadow_copy2_pwrite_state *state = NULL;
>+
>+	req = tevent_req_create(mem_ctx, &state,
>+				struct shadow_copy2_pwrite_state);
>+	if (req == NULL) {
>+		return NULL;
>+	}
>+	state->handle = handle;
>+	state->fsp = fsp;
>+
>+	subreq = SMB_VFS_NEXT_PWRITE_SEND(state,
>+					  ev,
>+					  handle,
>+					  fsp,
>+					  data,
>+					  n,
>+					  offset);
>+	if (tevent_req_nomem(subreq, req)) {
>+		return tevent_req_post(req, ev);
>+	}
>+	tevent_req_set_callback(subreq, shadow_copy2_pwrite_done, req);
>+
>+	return req;
>+}
>+
>+static void shadow_copy2_pwrite_done(struct tevent_req *subreq)
>+{
>+	struct tevent_req *req = tevent_req_callback_data(
>+		subreq, struct tevent_req);
>+	struct shadow_copy2_pwrite_state *state = tevent_req_data(
>+		req, struct shadow_copy2_pwrite_state);
>+
>+	state->ret = SMB_VFS_PWRITE_RECV(subreq, &state->vfs_aio_state);
>+	TALLOC_FREE(subreq);
>+	tevent_req_done(req);
>+}
>+
>+static ssize_t shadow_copy2_pwrite_recv(struct tevent_req *req,
>+					  struct vfs_aio_state *vfs_aio_state)
>+{
>+	struct shadow_copy2_pwrite_state *state = tevent_req_data(
>+		req, struct shadow_copy2_pwrite_state);
>+
>+	if (tevent_req_is_unix_error(req, &vfs_aio_state->error)) {
>+		if ((vfs_aio_state->error == EINVAL) &&
>+		    state->fsp->can_write)
>+		{
>+			vfs_aio_state->error = EROFS;
>+			errno = EROFS;
>+		}
>+		return -1;
>+	}
>+
>+	*vfs_aio_state = state->vfs_aio_state;
>+	return state->ret;
>+}
>+
> static int shadow_copy2_connect(struct vfs_handle_struct *handle,
> 				const char *service, const char *user)
> {
>-- 
>2.17.2
>

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