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Code

vfs_shadow_copy2: nicely deal with attempts to open previous version for writing

Browse Source 
Bug: https://bugzilla.samba.org/show_bug.cgi?id=13688

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
This commit is contained in:
Ralph Boehme 2018-11-23 14:08:15 +01:00
parent 14d6488d35
commit cf95756235
2 changed files with 122 additions and 3 deletions
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1
selftest/knownfail.d/samba3.blackbox
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@ -1 +0,0 @@
^samba3.blackbox.shadow_copy_torture.writing to shadow copy of a file\(fileserver\)

124
source3/modules/vfs_shadow_copy2.c
View File

@ -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;
@ -1376,15 +1378,27 @@ static int shadow_copy2_open(vfs_handle_struct *handle,
time_t timestamp = 0;
char *stripped = NULL;
char *tmp;
bool is_converted = false;
int saved_errno = 0;
int ret;
if (!shadow_copy2_strip_snapshot(talloc_tos(), handle,
if (!shadow_copy2_strip_snapshot_converted(talloc_tos(), handle,
smb_fname->base_name,
&timestamp, &stripped)) {
&timestamp, &stripped,
&is_converted)) {
return -1;
}
if (timestamp == 0) {
if (is_converted) {
/*
* 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.
*/
flags = O_RDONLY;
}
return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
}
@ -1398,6 +1412,14 @@ static int shadow_copy2_open(vfs_handle_struct *handle,
return -1;
}
/*
* 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.
*/
flags = O_RDONLY;
ret = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
if (ret == -1) {
saved_errno = errno;
@ -2887,6 +2909,101 @@ 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 == EBADF && 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);
if (state->ret == -1) {
tevent_req_error(req, state->vfs_aio_state.error);
return;
}
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 == EBADF) &&
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)
{
@ -3251,6 +3368,9 @@ static struct vfs_fn_pointers vfs_shadow_copy2_fns = {
.setxattr_fn = shadow_copy2_setxattr,
.chflags_fn = shadow_copy2_chflags,
.get_real_filename_fn = shadow_copy2_get_real_filename,
.pwrite_fn = shadow_copy2_pwrite,
.pwrite_send_fn = shadow_copy2_pwrite_send,
.pwrite_recv_fn = shadow_copy2_pwrite_recv,
.connectpath_fn = shadow_copy2_connectpath,
};