https://github.com/torvalds/linux
Tip revision: c5eb0a61238dd6faf37f58c9ce61c9980aaffd7a authored by Linus Torvalds on 08 May 2022, 20:54:17 UTC
Linux 5.18-rc6
Linux 5.18-rc6
Tip revision: c5eb0a6
fanotify.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/fanotify.h>
#include <linux/fdtable.h>
#include <linux/fsnotify_backend.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h> /* UINT_MAX */
#include <linux/mount.h>
#include <linux/sched.h>
#include <linux/sched/user.h>
#include <linux/sched/signal.h>
#include <linux/types.h>
#include <linux/wait.h>
#include <linux/audit.h>
#include <linux/sched/mm.h>
#include <linux/statfs.h>
#include <linux/stringhash.h>
#include "fanotify.h"
static bool fanotify_path_equal(struct path *p1, struct path *p2)
{
return p1->mnt == p2->mnt && p1->dentry == p2->dentry;
}
static unsigned int fanotify_hash_path(const struct path *path)
{
return hash_ptr(path->dentry, FANOTIFY_EVENT_HASH_BITS) ^
hash_ptr(path->mnt, FANOTIFY_EVENT_HASH_BITS);
}
static inline bool fanotify_fsid_equal(__kernel_fsid_t *fsid1,
__kernel_fsid_t *fsid2)
{
return fsid1->val[0] == fsid2->val[0] && fsid1->val[1] == fsid2->val[1];
}
static unsigned int fanotify_hash_fsid(__kernel_fsid_t *fsid)
{
return hash_32(fsid->val[0], FANOTIFY_EVENT_HASH_BITS) ^
hash_32(fsid->val[1], FANOTIFY_EVENT_HASH_BITS);
}
static bool fanotify_fh_equal(struct fanotify_fh *fh1,
struct fanotify_fh *fh2)
{
if (fh1->type != fh2->type || fh1->len != fh2->len)
return false;
return !fh1->len ||
!memcmp(fanotify_fh_buf(fh1), fanotify_fh_buf(fh2), fh1->len);
}
static unsigned int fanotify_hash_fh(struct fanotify_fh *fh)
{
long salt = (long)fh->type | (long)fh->len << 8;
/*
* full_name_hash() works long by long, so it handles fh buf optimally.
*/
return full_name_hash((void *)salt, fanotify_fh_buf(fh), fh->len);
}
static bool fanotify_fid_event_equal(struct fanotify_fid_event *ffe1,
struct fanotify_fid_event *ffe2)
{
/* Do not merge fid events without object fh */
if (!ffe1->object_fh.len)
return false;
return fanotify_fsid_equal(&ffe1->fsid, &ffe2->fsid) &&
fanotify_fh_equal(&ffe1->object_fh, &ffe2->object_fh);
}
static bool fanotify_info_equal(struct fanotify_info *info1,
struct fanotify_info *info2)
{
if (info1->dir_fh_totlen != info2->dir_fh_totlen ||
info1->dir2_fh_totlen != info2->dir2_fh_totlen ||
info1->file_fh_totlen != info2->file_fh_totlen ||
info1->name_len != info2->name_len ||
info1->name2_len != info2->name2_len)
return false;
if (info1->dir_fh_totlen &&
!fanotify_fh_equal(fanotify_info_dir_fh(info1),
fanotify_info_dir_fh(info2)))
return false;
if (info1->dir2_fh_totlen &&
!fanotify_fh_equal(fanotify_info_dir2_fh(info1),
fanotify_info_dir2_fh(info2)))
return false;
if (info1->file_fh_totlen &&
!fanotify_fh_equal(fanotify_info_file_fh(info1),
fanotify_info_file_fh(info2)))
return false;
if (info1->name_len &&
memcmp(fanotify_info_name(info1), fanotify_info_name(info2),
info1->name_len))
return false;
return !info1->name2_len ||
!memcmp(fanotify_info_name2(info1), fanotify_info_name2(info2),
info1->name2_len);
}
static bool fanotify_name_event_equal(struct fanotify_name_event *fne1,
struct fanotify_name_event *fne2)
{
struct fanotify_info *info1 = &fne1->info;
struct fanotify_info *info2 = &fne2->info;
/* Do not merge name events without dir fh */
if (!info1->dir_fh_totlen)
return false;
if (!fanotify_fsid_equal(&fne1->fsid, &fne2->fsid))
return false;
return fanotify_info_equal(info1, info2);
}
static bool fanotify_error_event_equal(struct fanotify_error_event *fee1,
struct fanotify_error_event *fee2)
{
/* Error events against the same file system are always merged. */
if (!fanotify_fsid_equal(&fee1->fsid, &fee2->fsid))
return false;
return true;
}
static bool fanotify_should_merge(struct fanotify_event *old,
struct fanotify_event *new)
{
pr_debug("%s: old=%p new=%p\n", __func__, old, new);
if (old->hash != new->hash ||
old->type != new->type || old->pid != new->pid)
return false;
/*
* We want to merge many dirent events in the same dir (i.e.
* creates/unlinks/renames), but we do not want to merge dirent
* events referring to subdirs with dirent events referring to
* non subdirs, otherwise, user won't be able to tell from a
* mask FAN_CREATE|FAN_DELETE|FAN_ONDIR if it describes mkdir+
* unlink pair or rmdir+create pair of events.
*/
if ((old->mask & FS_ISDIR) != (new->mask & FS_ISDIR))
return false;
/*
* FAN_RENAME event is reported with special info record types,
* so we cannot merge it with other events.
*/
if ((old->mask & FAN_RENAME) != (new->mask & FAN_RENAME))
return false;
switch (old->type) {
case FANOTIFY_EVENT_TYPE_PATH:
return fanotify_path_equal(fanotify_event_path(old),
fanotify_event_path(new));
case FANOTIFY_EVENT_TYPE_FID:
return fanotify_fid_event_equal(FANOTIFY_FE(old),
FANOTIFY_FE(new));
case FANOTIFY_EVENT_TYPE_FID_NAME:
return fanotify_name_event_equal(FANOTIFY_NE(old),
FANOTIFY_NE(new));
case FANOTIFY_EVENT_TYPE_FS_ERROR:
return fanotify_error_event_equal(FANOTIFY_EE(old),
FANOTIFY_EE(new));
default:
WARN_ON_ONCE(1);
}
return false;
}
/* Limit event merges to limit CPU overhead per event */
#define FANOTIFY_MAX_MERGE_EVENTS 128
/* and the list better be locked by something too! */
static int fanotify_merge(struct fsnotify_group *group,
struct fsnotify_event *event)
{
struct fanotify_event *old, *new = FANOTIFY_E(event);
unsigned int bucket = fanotify_event_hash_bucket(group, new);
struct hlist_head *hlist = &group->fanotify_data.merge_hash[bucket];
int i = 0;
pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
group, event, bucket);
/*
* Don't merge a permission event with any other event so that we know
* the event structure we have created in fanotify_handle_event() is the
* one we should check for permission response.
*/
if (fanotify_is_perm_event(new->mask))
return 0;
hlist_for_each_entry(old, hlist, merge_list) {
if (++i > FANOTIFY_MAX_MERGE_EVENTS)
break;
if (fanotify_should_merge(old, new)) {
old->mask |= new->mask;
if (fanotify_is_error_event(old->mask))
FANOTIFY_EE(old)->err_count++;
return 1;
}
}
return 0;
}
/*
* Wait for response to permission event. The function also takes care of
* freeing the permission event (or offloads that in case the wait is canceled
* by a signal). The function returns 0 in case access got allowed by userspace,
* -EPERM in case userspace disallowed the access, and -ERESTARTSYS in case
* the wait got interrupted by a signal.
*/
static int fanotify_get_response(struct fsnotify_group *group,
struct fanotify_perm_event *event,
struct fsnotify_iter_info *iter_info)
{
int ret;
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
ret = wait_event_killable(group->fanotify_data.access_waitq,
event->state == FAN_EVENT_ANSWERED);
/* Signal pending? */
if (ret < 0) {
spin_lock(&group->notification_lock);
/* Event reported to userspace and no answer yet? */
if (event->state == FAN_EVENT_REPORTED) {
/* Event will get freed once userspace answers to it */
event->state = FAN_EVENT_CANCELED;
spin_unlock(&group->notification_lock);
return ret;
}
/* Event not yet reported? Just remove it. */
if (event->state == FAN_EVENT_INIT) {
fsnotify_remove_queued_event(group, &event->fae.fse);
/* Permission events are not supposed to be hashed */
WARN_ON_ONCE(!hlist_unhashed(&event->fae.merge_list));
}
/*
* Event may be also answered in case signal delivery raced
* with wakeup. In that case we have nothing to do besides
* freeing the event and reporting error.
*/
spin_unlock(&group->notification_lock);
goto out;
}
/* userspace responded, convert to something usable */
switch (event->response & ~FAN_AUDIT) {
case FAN_ALLOW:
ret = 0;
break;
case FAN_DENY:
default:
ret = -EPERM;
}
/* Check if the response should be audited */
if (event->response & FAN_AUDIT)
audit_fanotify(event->response & ~FAN_AUDIT);
pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
group, event, ret);
out:
fsnotify_destroy_event(group, &event->fae.fse);
return ret;
}
/*
* This function returns a mask for an event that only contains the flags
* that have been specifically requested by the user. Flags that may have
* been included within the event mask, but have not been explicitly
* requested by the user, will not be present in the returned mask.
*/
static u32 fanotify_group_event_mask(struct fsnotify_group *group,
struct fsnotify_iter_info *iter_info,
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 |
FANOTIFY_EVENT_FLAGS;
const struct path *path = fsnotify_data_path(data, data_type);
unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
struct fsnotify_mark *mark;
int type;
pr_debug("%s: report_mask=%x mask=%x data=%p data_type=%d\n",
__func__, iter_info->report_mask, event_mask, data, data_type);
if (!fid_mode) {
/* Do we have path to open a file descriptor? */
if (!path)
return 0;
/* Path type events are only relevant for files and dirs */
if (!d_is_reg(path->dentry) && !d_can_lookup(path->dentry))
return 0;
} else if (!(fid_mode & FAN_REPORT_FID)) {
/* Do we have a directory inode to report? */
if (!dir && !(event_mask & FS_ISDIR))
return 0;
}
fsnotify_foreach_iter_type(type) {
if (!fsnotify_iter_should_report_type(iter_info, type))
continue;
mark = iter_info->marks[type];
/* Apply ignore mask regardless of ISDIR and ON_CHILD flags */
marks_ignored_mask |= mark->ignored_mask;
/*
* If the event is on dir and this mark doesn't care about
* events on dir, don't send it!
*/
if (event_mask & FS_ISDIR && !(mark->mask & FS_ISDIR))
continue;
/*
* If the event is on a child and this mark is on a parent not
* watching children, don't send it!
*/
if (type == FSNOTIFY_ITER_TYPE_PARENT &&
!(mark->mask & FS_EVENT_ON_CHILD))
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;
/*
* For dirent modification events (create/delete/move) that do not carry
* the child entry name information, we report FAN_ONDIR for mkdir/rmdir
* so user can differentiate them from creat/unlink.
*
* For backward compatibility and consistency, do not report FAN_ONDIR
* to user in legacy fanotify mode (reporting fd) and report FAN_ONDIR
* to user in fid mode for all event types.
*
* We never report FAN_EVENT_ON_CHILD to user, but we do pass it in to
* fanotify_alloc_event() when group is reporting fid as indication
* that event happened on child.
*/
if (fid_mode) {
/* Do not report event flags without any event */
if (!(test_mask & ~FANOTIFY_EVENT_FLAGS))
return 0;
} else {
user_mask &= ~FANOTIFY_EVENT_FLAGS;
}
return test_mask & user_mask;
}
/*
* Check size needed to encode fanotify_fh.
*
* Return size of encoded fh without fanotify_fh header.
* Return 0 on failure to encode.
*/
static int fanotify_encode_fh_len(struct inode *inode)
{
int dwords = 0;
int fh_len;
if (!inode)
return 0;
exportfs_encode_inode_fh(inode, NULL, &dwords, NULL);
fh_len = dwords << 2;
/*
* struct fanotify_error_event might be preallocated and is
* limited to MAX_HANDLE_SZ. This should never happen, but
* safeguard by forcing an invalid file handle.
*/
if (WARN_ON_ONCE(fh_len > MAX_HANDLE_SZ))
return 0;
return fh_len;
}
/*
* Encode fanotify_fh.
*
* Return total size of encoded fh including fanotify_fh header.
* Return 0 on failure to encode.
*/
static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
unsigned int fh_len, unsigned int *hash,
gfp_t gfp)
{
int dwords, type = 0;
char *ext_buf = NULL;
void *buf = fh->buf;
int err;
fh->type = FILEID_ROOT;
fh->len = 0;
fh->flags = 0;
/*
* Invalid FHs are used by FAN_FS_ERROR for errors not
* linked to any inode. The f_handle won't be reported
* back to userspace.
*/
if (!inode)
goto out;
/*
* !gpf means preallocated variable size fh, but fh_len could
* be zero in that case if encoding fh len failed.
*/
err = -ENOENT;
if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4) || fh_len > MAX_HANDLE_SZ)
goto out_err;
/* No external buffer in a variable size allocated fh */
if (gfp && fh_len > FANOTIFY_INLINE_FH_LEN) {
/* Treat failure to allocate fh as failure to encode fh */
err = -ENOMEM;
ext_buf = kmalloc(fh_len, gfp);
if (!ext_buf)
goto out_err;
*fanotify_fh_ext_buf_ptr(fh) = ext_buf;
buf = ext_buf;
fh->flags |= FANOTIFY_FH_FLAG_EXT_BUF;
}
dwords = fh_len >> 2;
type = exportfs_encode_inode_fh(inode, buf, &dwords, NULL);
err = -EINVAL;
if (!type || type == FILEID_INVALID || fh_len != dwords << 2)
goto out_err;
fh->type = type;
fh->len = fh_len;
out:
/*
* Mix fh into event merge key. Hash might be NULL in case of
* unhashed FID events (i.e. FAN_FS_ERROR).
*/
if (hash)
*hash ^= fanotify_hash_fh(fh);
return FANOTIFY_FH_HDR_LEN + fh_len;
out_err:
pr_warn_ratelimited("fanotify: failed to encode fid (type=%d, len=%d, err=%i)\n",
type, fh_len, err);
kfree(ext_buf);
*fanotify_fh_ext_buf_ptr(fh) = NULL;
/* Report the event without a file identifier on encode error */
fh->type = FILEID_INVALID;
fh->len = 0;
return 0;
}
/*
* FAN_REPORT_FID is ambiguous in that it reports the fid of the child for
* some events and the fid of the parent for create/delete/move events.
*
* With the FAN_REPORT_TARGET_FID flag, the fid of the child is reported
* also in create/delete/move events in addition to the fid of the parent
* and the name of the child.
*/
static inline bool fanotify_report_child_fid(unsigned int fid_mode, u32 mask)
{
if (mask & ALL_FSNOTIFY_DIRENT_EVENTS)
return (fid_mode & FAN_REPORT_TARGET_FID);
return (fid_mode & FAN_REPORT_FID) && !(mask & FAN_ONDIR);
}
/*
* The inode to use as identifier when reporting fid depends on the event
* and the group flags.
*
* With the group flag FAN_REPORT_TARGET_FID, always report the child fid.
*
* Without the group flag FAN_REPORT_TARGET_FID, report the modified directory
* fid on dirent events and the child fid otherwise.
*
* For example:
* FS_ATTRIB reports the child fid even if reported on a watched parent.
* FS_CREATE reports the modified dir fid without FAN_REPORT_TARGET_FID.
* and reports the created child fid with FAN_REPORT_TARGET_FID.
*/
static struct inode *fanotify_fid_inode(u32 event_mask, const void *data,
int data_type, struct inode *dir,
unsigned int fid_mode)
{
if ((event_mask & ALL_FSNOTIFY_DIRENT_EVENTS) &&
!(fid_mode & FAN_REPORT_TARGET_FID))
return dir;
return fsnotify_data_inode(data, data_type);
}
/*
* The inode to use as identifier when reporting dir fid depends on the event.
* Report the modified directory inode on dirent modification events.
* Report the "victim" inode if "victim" is a directory.
* Report the parent inode if "victim" is not a directory and event is
* reported to parent.
* Otherwise, do not report dir fid.
*/
static struct inode *fanotify_dfid_inode(u32 event_mask, const void *data,
int data_type, struct inode *dir)
{
struct inode *inode = fsnotify_data_inode(data, data_type);
if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)
return dir;
if (inode && S_ISDIR(inode->i_mode))
return inode;
return dir;
}
static struct fanotify_event *fanotify_alloc_path_event(const struct path *path,
unsigned int *hash,
gfp_t gfp)
{
struct fanotify_path_event *pevent;
pevent = kmem_cache_alloc(fanotify_path_event_cachep, gfp);
if (!pevent)
return NULL;
pevent->fae.type = FANOTIFY_EVENT_TYPE_PATH;
pevent->path = *path;
*hash ^= fanotify_hash_path(path);
path_get(path);
return &pevent->fae;
}
static struct fanotify_event *fanotify_alloc_perm_event(const struct path *path,
gfp_t gfp)
{
struct fanotify_perm_event *pevent;
pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
if (!pevent)
return NULL;
pevent->fae.type = FANOTIFY_EVENT_TYPE_PATH_PERM;
pevent->response = 0;
pevent->state = FAN_EVENT_INIT;
pevent->path = *path;
path_get(path);
return &pevent->fae;
}
static struct fanotify_event *fanotify_alloc_fid_event(struct inode *id,
__kernel_fsid_t *fsid,
unsigned int *hash,
gfp_t gfp)
{
struct fanotify_fid_event *ffe;
ffe = kmem_cache_alloc(fanotify_fid_event_cachep, gfp);
if (!ffe)
return NULL;
ffe->fae.type = FANOTIFY_EVENT_TYPE_FID;
ffe->fsid = *fsid;
*hash ^= fanotify_hash_fsid(fsid);
fanotify_encode_fh(&ffe->object_fh, id, fanotify_encode_fh_len(id),
hash, gfp);
return &ffe->fae;
}
static struct fanotify_event *fanotify_alloc_name_event(struct inode *dir,
__kernel_fsid_t *fsid,
const struct qstr *name,
struct inode *child,
struct dentry *moved,
unsigned int *hash,
gfp_t gfp)
{
struct fanotify_name_event *fne;
struct fanotify_info *info;
struct fanotify_fh *dfh, *ffh;
struct inode *dir2 = moved ? d_inode(moved->d_parent) : NULL;
const struct qstr *name2 = moved ? &moved->d_name : NULL;
unsigned int dir_fh_len = fanotify_encode_fh_len(dir);
unsigned int dir2_fh_len = fanotify_encode_fh_len(dir2);
unsigned int child_fh_len = fanotify_encode_fh_len(child);
unsigned long name_len = name ? name->len : 0;
unsigned long name2_len = name2 ? name2->len : 0;
unsigned int len, size;
/* Reserve terminating null byte even for empty name */
size = sizeof(*fne) + name_len + name2_len + 2;
if (dir_fh_len)
size += FANOTIFY_FH_HDR_LEN + dir_fh_len;
if (dir2_fh_len)
size += FANOTIFY_FH_HDR_LEN + dir2_fh_len;
if (child_fh_len)
size += FANOTIFY_FH_HDR_LEN + child_fh_len;
fne = kmalloc(size, gfp);
if (!fne)
return NULL;
fne->fae.type = FANOTIFY_EVENT_TYPE_FID_NAME;
fne->fsid = *fsid;
*hash ^= fanotify_hash_fsid(fsid);
info = &fne->info;
fanotify_info_init(info);
if (dir_fh_len) {
dfh = fanotify_info_dir_fh(info);
len = fanotify_encode_fh(dfh, dir, dir_fh_len, hash, 0);
fanotify_info_set_dir_fh(info, len);
}
if (dir2_fh_len) {
dfh = fanotify_info_dir2_fh(info);
len = fanotify_encode_fh(dfh, dir2, dir2_fh_len, hash, 0);
fanotify_info_set_dir2_fh(info, len);
}
if (child_fh_len) {
ffh = fanotify_info_file_fh(info);
len = fanotify_encode_fh(ffh, child, child_fh_len, hash, 0);
fanotify_info_set_file_fh(info, len);
}
if (name_len) {
fanotify_info_copy_name(info, name);
*hash ^= full_name_hash((void *)name_len, name->name, name_len);
}
if (name2_len) {
fanotify_info_copy_name2(info, name2);
*hash ^= full_name_hash((void *)name2_len, name2->name,
name2_len);
}
pr_debug("%s: size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n",
__func__, size, dir_fh_len, child_fh_len,
info->name_len, info->name_len, fanotify_info_name(info));
if (dir2_fh_len) {
pr_debug("%s: dir2_fh_len=%u name2_len=%u name2='%.*s'\n",
__func__, dir2_fh_len, info->name2_len,
info->name2_len, fanotify_info_name2(info));
}
return &fne->fae;
}
static struct fanotify_event *fanotify_alloc_error_event(
struct fsnotify_group *group,
__kernel_fsid_t *fsid,
const void *data, int data_type,
unsigned int *hash)
{
struct fs_error_report *report =
fsnotify_data_error_report(data, data_type);
struct inode *inode;
struct fanotify_error_event *fee;
int fh_len;
if (WARN_ON_ONCE(!report))
return NULL;
fee = mempool_alloc(&group->fanotify_data.error_events_pool, GFP_NOFS);
if (!fee)
return NULL;
fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
fee->error = report->error;
fee->err_count = 1;
fee->fsid = *fsid;
inode = report->inode;
fh_len = fanotify_encode_fh_len(inode);
/* Bad fh_len. Fallback to using an invalid fh. Should never happen. */
if (!fh_len && inode)
inode = NULL;
fanotify_encode_fh(&fee->object_fh, inode, fh_len, NULL, 0);
*hash ^= fanotify_hash_fsid(fsid);
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, u32 match_mask)
{
struct fanotify_event *event = NULL;
gfp_t gfp = GFP_KERNEL_ACCOUNT;
unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
struct inode *id = fanotify_fid_inode(mask, data, data_type, dir,
fid_mode);
struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir);
const struct path *path = fsnotify_data_path(data, data_type);
struct mem_cgroup *old_memcg;
struct dentry *moved = NULL;
struct inode *child = NULL;
bool name_event = false;
unsigned int hash = 0;
bool ondir = mask & FAN_ONDIR;
struct pid *pid;
if ((fid_mode & FAN_REPORT_DIR_FID) && dirid) {
/*
* For certain events and group flags, report the child fid
* in addition to reporting the parent fid and maybe child name.
*/
if (fanotify_report_child_fid(fid_mode, mask) && id != dirid)
child = id;
id = dirid;
/*
* We record file name only in a group with FAN_REPORT_NAME
* and when we have a directory inode to report.
*
* For directory entry modification event, we record the fid of
* the directory and the name of the modified entry.
*
* For event on non-directory that is reported to parent, we
* record the fid of the parent and the name of the child.
*
* Even if not reporting name, we need a variable length
* fanotify_name_event if reporting both parent and child fids.
*/
if (!(fid_mode & FAN_REPORT_NAME)) {
name_event = !!child;
file_name = NULL;
} else if ((mask & ALL_FSNOTIFY_DIRENT_EVENTS) || !ondir) {
name_event = true;
}
/*
* 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) {
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);
}
}
}
/*
* For queues with unlimited length lost events are not expected and
* can possibly have security implications. Avoid losing events when
* memory is short. For the limited size queues, avoid OOM killer in the
* target monitoring memcg as it may have security repercussion.
*/
if (group->max_events == UINT_MAX)
gfp |= __GFP_NOFAIL;
else
gfp |= __GFP_RETRY_MAYFAIL;
/* Whoever is interested in the event, pays for the allocation. */
old_memcg = set_active_memcg(group->memcg);
if (fanotify_is_perm_event(mask)) {
event = fanotify_alloc_perm_event(path, gfp);
} else if (fanotify_is_error_event(mask)) {
event = fanotify_alloc_error_event(group, fsid, data,
data_type, &hash);
} else if (name_event && (file_name || moved || child)) {
event = fanotify_alloc_name_event(dirid, fsid, file_name, child,
moved, &hash, gfp);
} else if (fid_mode) {
event = fanotify_alloc_fid_event(id, fsid, &hash, gfp);
} else {
event = fanotify_alloc_path_event(path, &hash, gfp);
}
if (!event)
goto out;
if (FAN_GROUP_FLAG(group, FAN_REPORT_TID))
pid = get_pid(task_pid(current));
else
pid = get_pid(task_tgid(current));
/* Mix event info, FAN_ONDIR flag and pid into event merge key */
hash ^= hash_long((unsigned long)pid | ondir, FANOTIFY_EVENT_HASH_BITS);
fanotify_init_event(event, hash, mask);
event->pid = pid;
out:
set_active_memcg(old_memcg);
return event;
}
/*
* Get cached fsid of the filesystem containing the object from any connector.
* All connectors are supposed to have the same fsid, but we do not verify that
* here.
*/
static __kernel_fsid_t fanotify_get_fsid(struct fsnotify_iter_info *iter_info)
{
int type;
__kernel_fsid_t fsid = {};
fsnotify_foreach_iter_type(type) {
struct fsnotify_mark_connector *conn;
if (!fsnotify_iter_should_report_type(iter_info, type))
continue;
conn = READ_ONCE(iter_info->marks[type]->connector);
/* Mark is just getting destroyed or created? */
if (!conn)
continue;
if (!(conn->flags & FSNOTIFY_CONN_FLAG_HAS_FSID))
continue;
/* Pairs with smp_wmb() in fsnotify_add_mark_list() */
smp_rmb();
fsid = conn->fsid;
if (WARN_ON_ONCE(!fsid.val[0] && !fsid.val[1]))
continue;
return fsid;
}
return fsid;
}
/*
* Add an event to hash table for faster merge.
*/
static void fanotify_insert_event(struct fsnotify_group *group,
struct fsnotify_event *fsn_event)
{
struct fanotify_event *event = FANOTIFY_E(fsn_event);
unsigned int bucket = fanotify_event_hash_bucket(group, event);
struct hlist_head *hlist = &group->fanotify_data.merge_hash[bucket];
assert_spin_locked(&group->notification_lock);
if (!fanotify_is_hashed_event(event->mask))
return;
pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
group, event, bucket);
hlist_add_head(&event->merge_list, hlist);
}
static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
const void *data, int data_type,
struct inode *dir,
const struct qstr *file_name, u32 cookie,
struct fsnotify_iter_info *iter_info)
{
int ret = 0;
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);
BUILD_BUG_ON(FAN_ATTRIB != FS_ATTRIB);
BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
BUILD_BUG_ON(FAN_MOVED_TO != FS_MOVED_TO);
BUILD_BUG_ON(FAN_MOVED_FROM != FS_MOVED_FROM);
BUILD_BUG_ON(FAN_CREATE != FS_CREATE);
BUILD_BUG_ON(FAN_DELETE != FS_DELETE);
BUILD_BUG_ON(FAN_DELETE_SELF != FS_DELETE_SELF);
BUILD_BUG_ON(FAN_MOVE_SELF != FS_MOVE_SELF);
BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC);
BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR);
BUILD_BUG_ON(FAN_RENAME != FS_RENAME);
BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 21);
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 report_mask=%x\n", __func__,
group, mask, match_mask);
if (fanotify_is_perm_event(mask)) {
/*
* fsnotify_prepare_user_wait() fails if we race with mark
* deletion. Just let the operation pass in that case.
*/
if (!fsnotify_prepare_user_wait(iter_info))
return 0;
}
if (FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS)) {
fsid = fanotify_get_fsid(iter_info);
/* Racing with mark destruction or creation? */
if (!fsid.val[0] && !fsid.val[1])
return 0;
}
event = fanotify_alloc_event(group, mask, data, data_type, dir,
file_name, &fsid, match_mask);
ret = -ENOMEM;
if (unlikely(!event)) {
/*
* We don't queue overflow events for permission events as
* there the access is denied and so no event is in fact lost.
*/
if (!fanotify_is_perm_event(mask))
fsnotify_queue_overflow(group);
goto finish;
}
fsn_event = &event->fse;
ret = fsnotify_insert_event(group, fsn_event, fanotify_merge,
fanotify_insert_event);
if (ret) {
/* Permission events shouldn't be merged */
BUG_ON(ret == 1 && mask & FANOTIFY_PERM_EVENTS);
/* Our event wasn't used in the end. Free it. */
fsnotify_destroy_event(group, fsn_event);
ret = 0;
} else if (fanotify_is_perm_event(mask)) {
ret = fanotify_get_response(group, FANOTIFY_PERM(event),
iter_info);
}
finish:
if (fanotify_is_perm_event(mask))
fsnotify_finish_user_wait(iter_info);
return ret;
}
static void fanotify_free_group_priv(struct fsnotify_group *group)
{
kfree(group->fanotify_data.merge_hash);
if (group->fanotify_data.ucounts)
dec_ucount(group->fanotify_data.ucounts,
UCOUNT_FANOTIFY_GROUPS);
if (mempool_initialized(&group->fanotify_data.error_events_pool))
mempool_exit(&group->fanotify_data.error_events_pool);
}
static void fanotify_free_path_event(struct fanotify_event *event)
{
path_put(fanotify_event_path(event));
kmem_cache_free(fanotify_path_event_cachep, FANOTIFY_PE(event));
}
static void fanotify_free_perm_event(struct fanotify_event *event)
{
path_put(fanotify_event_path(event));
kmem_cache_free(fanotify_perm_event_cachep, FANOTIFY_PERM(event));
}
static void fanotify_free_fid_event(struct fanotify_event *event)
{
struct fanotify_fid_event *ffe = FANOTIFY_FE(event);
if (fanotify_fh_has_ext_buf(&ffe->object_fh))
kfree(fanotify_fh_ext_buf(&ffe->object_fh));
kmem_cache_free(fanotify_fid_event_cachep, ffe);
}
static void fanotify_free_name_event(struct fanotify_event *event)
{
kfree(FANOTIFY_NE(event));
}
static void fanotify_free_error_event(struct fsnotify_group *group,
struct fanotify_event *event)
{
struct fanotify_error_event *fee = FANOTIFY_EE(event);
mempool_free(fee, &group->fanotify_data.error_events_pool);
}
static void fanotify_free_event(struct fsnotify_group *group,
struct fsnotify_event *fsn_event)
{
struct fanotify_event *event;
event = FANOTIFY_E(fsn_event);
put_pid(event->pid);
switch (event->type) {
case FANOTIFY_EVENT_TYPE_PATH:
fanotify_free_path_event(event);
break;
case FANOTIFY_EVENT_TYPE_PATH_PERM:
fanotify_free_perm_event(event);
break;
case FANOTIFY_EVENT_TYPE_FID:
fanotify_free_fid_event(event);
break;
case FANOTIFY_EVENT_TYPE_FID_NAME:
fanotify_free_name_event(event);
break;
case FANOTIFY_EVENT_TYPE_OVERFLOW:
kfree(event);
break;
case FANOTIFY_EVENT_TYPE_FS_ERROR:
fanotify_free_error_event(group, event);
break;
default:
WARN_ON_ONCE(1);
}
}
static void fanotify_freeing_mark(struct fsnotify_mark *mark,
struct fsnotify_group *group)
{
if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS))
dec_ucount(group->fanotify_data.ucounts, UCOUNT_FANOTIFY_MARKS);
}
static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
{
kmem_cache_free(fanotify_mark_cache, fsn_mark);
}
const struct fsnotify_ops fanotify_fsnotify_ops = {
.handle_event = fanotify_handle_event,
.free_group_priv = fanotify_free_group_priv,
.free_event = fanotify_free_event,
.freeing_mark = fanotify_freeing_mark,
.free_mark = fanotify_free_mark,
};