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fanotify: record either old name new name or both for FAN_RENAME

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We do not want to report the dirfid+name of a directory whose
inode/sb are not watched, because watcher may not have permissions
to see the directory content.

Use an internal iter_info to indicate to fanotify_alloc_event()
which marks of this group are watching FAN_RENAME, so it can decide
if we need to record only the old parent+name, new parent+name or both.

Link: https://lore.kernel.org/r/20211129201537.1932819-10-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
[JK: Modified code to pass around only mask of mark types matching
generated event]
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein 2021-11-29 22:15:35 +02:00 committed by Jan Kara
parent 3982534ba5
commit 2bfbcccde6
1 changed files with 44 additions and 15 deletions
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59
fs/notify/fanotify/fanotify.c
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@ -284,8 +284,9 @@ out:
*/
static u32 fanotify_group_event_mask(struct fsnotify_group *group,
struct fsnotify_iter_info *iter_info,
u32 event_mask, const void *data,
int data_type, struct inode *dir)
u32 *match_mask, u32 event_mask,
const void *data, int data_type,
struct inode *dir)
{
__u32 marks_mask = 0, marks_ignored_mask = 0;
__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS |
@ -335,6 +336,9 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
continue;
marks_mask |= mark->mask;
/* Record the mark types of this group that matched the event */
*match_mask |= 1U << type;
}
test_mask = event_mask & marks_mask & ~marks_ignored_mask;
@ -701,11 +705,11 @@ static struct fanotify_event *fanotify_alloc_error_event(
return &fee->fae;
}
static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
u32 mask, const void *data,
int data_type, struct inode *dir,
const struct qstr *file_name,
__kernel_fsid_t *fsid)
static struct fanotify_event *fanotify_alloc_event(
struct fsnotify_group *group,
u32 mask, const void *data, int data_type,
struct inode *dir, const struct qstr *file_name,
__kernel_fsid_t *fsid, u32 match_mask)
{
struct fanotify_event *event = NULL;
gfp_t gfp = GFP_KERNEL_ACCOUNT;
@ -753,13 +757,36 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
}
/*
* In the special case of FAN_RENAME event, we record both
* old and new parent+name.
* In the special case of FAN_RENAME event, use the match_mask
* to determine if we need to report only the old parent+name,
* only the new parent+name or both.
* 'dirid' and 'file_name' are the old parent+name and
* 'moved' has the new parent+name.
*/
if (mask & FAN_RENAME)
moved = fsnotify_data_dentry(data, data_type);
if (mask & FAN_RENAME) {
bool report_old, report_new;
if (WARN_ON_ONCE(!match_mask))
return NULL;
/* Report both old and new parent+name if sb watching */
report_old = report_new =
match_mask & (1U << FSNOTIFY_ITER_TYPE_SB);
report_old |=
match_mask & (1U << FSNOTIFY_ITER_TYPE_INODE);
report_new |=
match_mask & (1U << FSNOTIFY_ITER_TYPE_INODE2);
if (!report_old) {
/* Do not report old parent+name */
dirid = NULL;
file_name = NULL;
}
if (report_new) {
/* Report new parent+name */
moved = fsnotify_data_dentry(data, data_type);
}
}
}
/*
@ -872,6 +899,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
struct fanotify_event *event;
struct fsnotify_event *fsn_event;
__kernel_fsid_t fsid = {};
u32 match_mask = 0;
BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
@ -897,12 +925,13 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20);
mask = fanotify_group_event_mask(group, iter_info, mask, data,
data_type, dir);
mask = fanotify_group_event_mask(group, iter_info, &match_mask,
mask, data, data_type, dir);
if (!mask)
return 0;
pr_debug("%s: group=%p mask=%x\n", __func__, group, mask);
pr_debug("%s: group=%p mask=%x report_mask=%x\n", __func__,
group, mask, match_mask);
if (fanotify_is_perm_event(mask)) {
/*
@ -921,7 +950,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
}
event = fanotify_alloc_event(group, mask, data, data_type, dir,
file_name, &fsid);
file_name, &fsid, match_mask);
ret = -ENOMEM;
if (unlikely(!event)) {
/*