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/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/fsnotify_backend.h>
#include <linux/path.h>
#include <linux/slab.h>
#include <linux/exportfs.h>
extern struct kmem_cache *fanotify_mark_cache;
extern struct kmem_cache *fanotify_event_cachep;
extern struct kmem_cache *fanotify_perm_event_cachep;
/*
* 3 dwords are sufficient for most local fs (64bit ino, 32bit generation).
* For 32bit arch, fid increases the size of fanotify_event by 12 bytes and
* fh_* fields increase the size of fanotify_event by another 4 bytes.
* For 64bit arch, fid increases the size of fanotify_fid by 8 bytes and
* fh_* fields are packed in a hole after mask.
*/
#if BITS_PER_LONG == 32
#define FANOTIFY_INLINE_FH_LEN (3 << 2)
#else
#define FANOTIFY_INLINE_FH_LEN (4 << 2)
#endif
struct fanotify_fid {
__kernel_fsid_t fsid;
union {
unsigned char fh[FANOTIFY_INLINE_FH_LEN];
unsigned char *ext_fh;
};
};
static inline void *fanotify_fid_fh(struct fanotify_fid *fid,
unsigned int fh_len)
{
return fh_len <= FANOTIFY_INLINE_FH_LEN ? fid->fh : fid->ext_fh;
}
static inline bool fanotify_fid_equal(struct fanotify_fid *fid1,
struct fanotify_fid *fid2,
unsigned int fh_len)
{
return fid1->fsid.val[0] == fid2->fsid.val[0] &&
fid1->fsid.val[1] == fid2->fsid.val[1] &&
!memcmp(fanotify_fid_fh(fid1, fh_len),
fanotify_fid_fh(fid2, fh_len), fh_len);
}
/*
* Structure for normal fanotify events. It gets allocated in
* fanotify_handle_event() and freed when the information is retrieved by
* userspace
*/
struct fanotify_event {
struct fsnotify_event fse;
u32 mask;
/*
* Those fields are outside fanotify_fid to pack fanotify_event nicely
* on 64bit arch and to use fh_type as an indication of whether path
* or fid are used in the union:
* FILEID_ROOT (0) for path, > 0 for fid, FILEID_INVALID for neither.
*/
u8 fh_type;
u8 fh_len;
u16 pad;
union {
/*
* We hold ref to this path so it may be dereferenced at any
* point during this object's lifetime
*/
struct path path;
/*
* With FAN_REPORT_FID, we do not hold any reference on the
* victim object. Instead we store its NFS file handle and its
* filesystem's fsid as a unique identifier.
*/
struct fanotify_fid fid;
};
struct pid *pid;
};
static inline bool fanotify_event_has_path(struct fanotify_event *event)
{
return event->fh_type == FILEID_ROOT;
}
static inline bool fanotify_event_has_fid(struct fanotify_event *event)
{
return event->fh_type != FILEID_ROOT &&
event->fh_type != FILEID_INVALID;
}
static inline bool fanotify_event_has_ext_fh(struct fanotify_event *event)
{
return fanotify_event_has_fid(event) &&
event->fh_len > FANOTIFY_INLINE_FH_LEN;
}
static inline void *fanotify_event_fh(struct fanotify_event *event)
{
return fanotify_fid_fh(&event->fid, event->fh_len);
}
/*
* Structure for permission fanotify events. It gets allocated and freed in
* fanotify_handle_event() since we wait there for user response. When the
* information is retrieved by userspace the structure is moved from
* group->notification_list to group->fanotify_data.access_list to wait for
* user response.
*/
struct fanotify_perm_event {
struct fanotify_event fae;
int response; /* userspace answer to question */
int fd; /* fd we passed to userspace for this event */
};
static inline struct fanotify_perm_event *
FANOTIFY_PE(struct fsnotify_event *fse)
{
return container_of(fse, struct fanotify_perm_event, fae.fse);
}
static inline bool fanotify_is_perm_event(u32 mask)
{
return IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS) &&
mask & FANOTIFY_PERM_EVENTS;
}
static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)
{
return container_of(fse, struct fanotify_event, fse);
}
struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
struct inode *inode, u32 mask,
const struct path *path);
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