https://github.com/torvalds/linux
Tip revision: e783362eb54cd99b2cac8b3a9aeac942e6f6ac07 authored by Linus Torvalds on 23 January 2022, 08:12:53 UTC
Linux 5.17-rc1
Linux 5.17-rc1
Tip revision: e783362
fanotify.h
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/fsnotify_backend.h>
#include <linux/path.h>
#include <linux/slab.h>
#include <linux/exportfs.h>
#include <linux/hashtable.h>
extern struct kmem_cache *fanotify_mark_cache;
extern struct kmem_cache *fanotify_fid_event_cachep;
extern struct kmem_cache *fanotify_path_event_cachep;
extern struct kmem_cache *fanotify_perm_event_cachep;
/* Possible states of the permission event */
enum {
FAN_EVENT_INIT,
FAN_EVENT_REPORTED,
FAN_EVENT_ANSWERED,
FAN_EVENT_CANCELED,
};
/*
* 3 dwords are sufficient for most local fs (64bit ino, 32bit generation).
* fh buf should be dword aligned. On 64bit arch, the ext_buf pointer is
* stored in either the first or last 2 dwords.
*/
#define FANOTIFY_INLINE_FH_LEN (3 << 2)
#define FANOTIFY_FH_HDR_LEN offsetof(struct fanotify_fh, buf)
/* Fixed size struct for file handle */
struct fanotify_fh {
u8 type;
u8 len;
#define FANOTIFY_FH_FLAG_EXT_BUF 1
u8 flags;
u8 pad;
unsigned char buf[];
} __aligned(4);
/* Variable size struct for dir file handle + child file handle + name */
struct fanotify_info {
/* size of dir_fh/file_fh including fanotify_fh hdr size */
u8 dir_fh_totlen;
u8 dir2_fh_totlen;
u8 file_fh_totlen;
u8 name_len;
u8 name2_len;
u8 pad[3];
unsigned char buf[];
/*
* (struct fanotify_fh) dir_fh starts at buf[0]
* (optional) dir2_fh starts at buf[dir_fh_totlen]
* (optional) file_fh starts at buf[dir_fh_totlen + dir2_fh_totlen]
* name starts at buf[dir_fh_totlen + dir2_fh_totlen + file_fh_totlen]
* ...
*/
#define FANOTIFY_DIR_FH_SIZE(info) ((info)->dir_fh_totlen)
#define FANOTIFY_DIR2_FH_SIZE(info) ((info)->dir2_fh_totlen)
#define FANOTIFY_FILE_FH_SIZE(info) ((info)->file_fh_totlen)
#define FANOTIFY_NAME_SIZE(info) ((info)->name_len + 1)
#define FANOTIFY_NAME2_SIZE(info) ((info)->name2_len + 1)
#define FANOTIFY_DIR_FH_OFFSET(info) 0
#define FANOTIFY_DIR2_FH_OFFSET(info) \
(FANOTIFY_DIR_FH_OFFSET(info) + FANOTIFY_DIR_FH_SIZE(info))
#define FANOTIFY_FILE_FH_OFFSET(info) \
(FANOTIFY_DIR2_FH_OFFSET(info) + FANOTIFY_DIR2_FH_SIZE(info))
#define FANOTIFY_NAME_OFFSET(info) \
(FANOTIFY_FILE_FH_OFFSET(info) + FANOTIFY_FILE_FH_SIZE(info))
#define FANOTIFY_NAME2_OFFSET(info) \
(FANOTIFY_NAME_OFFSET(info) + FANOTIFY_NAME_SIZE(info))
#define FANOTIFY_DIR_FH_BUF(info) \
((info)->buf + FANOTIFY_DIR_FH_OFFSET(info))
#define FANOTIFY_DIR2_FH_BUF(info) \
((info)->buf + FANOTIFY_DIR2_FH_OFFSET(info))
#define FANOTIFY_FILE_FH_BUF(info) \
((info)->buf + FANOTIFY_FILE_FH_OFFSET(info))
#define FANOTIFY_NAME_BUF(info) \
((info)->buf + FANOTIFY_NAME_OFFSET(info))
#define FANOTIFY_NAME2_BUF(info) \
((info)->buf + FANOTIFY_NAME2_OFFSET(info))
} __aligned(4);
static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh)
{
return (fh->flags & FANOTIFY_FH_FLAG_EXT_BUF);
}
static inline char **fanotify_fh_ext_buf_ptr(struct fanotify_fh *fh)
{
BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN % 4);
BUILD_BUG_ON(__alignof__(char *) - 4 + sizeof(char *) >
FANOTIFY_INLINE_FH_LEN);
return (char **)ALIGN((unsigned long)(fh->buf), __alignof__(char *));
}
static inline void *fanotify_fh_ext_buf(struct fanotify_fh *fh)
{
return *fanotify_fh_ext_buf_ptr(fh);
}
static inline void *fanotify_fh_buf(struct fanotify_fh *fh)
{
return fanotify_fh_has_ext_buf(fh) ? fanotify_fh_ext_buf(fh) : fh->buf;
}
static inline int fanotify_info_dir_fh_len(struct fanotify_info *info)
{
if (!info->dir_fh_totlen ||
WARN_ON_ONCE(info->dir_fh_totlen < FANOTIFY_FH_HDR_LEN))
return 0;
return info->dir_fh_totlen - FANOTIFY_FH_HDR_LEN;
}
static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *info)
{
BUILD_BUG_ON(offsetof(struct fanotify_info, buf) % 4);
return (struct fanotify_fh *)FANOTIFY_DIR_FH_BUF(info);
}
static inline int fanotify_info_dir2_fh_len(struct fanotify_info *info)
{
if (!info->dir2_fh_totlen ||
WARN_ON_ONCE(info->dir2_fh_totlen < FANOTIFY_FH_HDR_LEN))
return 0;
return info->dir2_fh_totlen - FANOTIFY_FH_HDR_LEN;
}
static inline struct fanotify_fh *fanotify_info_dir2_fh(struct fanotify_info *info)
{
return (struct fanotify_fh *)FANOTIFY_DIR2_FH_BUF(info);
}
static inline int fanotify_info_file_fh_len(struct fanotify_info *info)
{
if (!info->file_fh_totlen ||
WARN_ON_ONCE(info->file_fh_totlen < FANOTIFY_FH_HDR_LEN))
return 0;
return info->file_fh_totlen - FANOTIFY_FH_HDR_LEN;
}
static inline struct fanotify_fh *fanotify_info_file_fh(struct fanotify_info *info)
{
return (struct fanotify_fh *)FANOTIFY_FILE_FH_BUF(info);
}
static inline char *fanotify_info_name(struct fanotify_info *info)
{
if (!info->name_len)
return NULL;
return FANOTIFY_NAME_BUF(info);
}
static inline char *fanotify_info_name2(struct fanotify_info *info)
{
if (!info->name2_len)
return NULL;
return FANOTIFY_NAME2_BUF(info);
}
static inline void fanotify_info_init(struct fanotify_info *info)
{
BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN + MAX_HANDLE_SZ > U8_MAX);
BUILD_BUG_ON(NAME_MAX > U8_MAX);
info->dir_fh_totlen = 0;
info->dir2_fh_totlen = 0;
info->file_fh_totlen = 0;
info->name_len = 0;
info->name2_len = 0;
}
/* These set/copy helpers MUST be called by order */
static inline void fanotify_info_set_dir_fh(struct fanotify_info *info,
unsigned int totlen)
{
if (WARN_ON_ONCE(info->dir2_fh_totlen > 0) ||
WARN_ON_ONCE(info->file_fh_totlen > 0) ||
WARN_ON_ONCE(info->name_len > 0) ||
WARN_ON_ONCE(info->name2_len > 0))
return;
info->dir_fh_totlen = totlen;
}
static inline void fanotify_info_set_dir2_fh(struct fanotify_info *info,
unsigned int totlen)
{
if (WARN_ON_ONCE(info->file_fh_totlen > 0) ||
WARN_ON_ONCE(info->name_len > 0) ||
WARN_ON_ONCE(info->name2_len > 0))
return;
info->dir2_fh_totlen = totlen;
}
static inline void fanotify_info_set_file_fh(struct fanotify_info *info,
unsigned int totlen)
{
if (WARN_ON_ONCE(info->name_len > 0) ||
WARN_ON_ONCE(info->name2_len > 0))
return;
info->file_fh_totlen = totlen;
}
static inline void fanotify_info_copy_name(struct fanotify_info *info,
const struct qstr *name)
{
if (WARN_ON_ONCE(name->len > NAME_MAX) ||
WARN_ON_ONCE(info->name2_len > 0))
return;
info->name_len = name->len;
strcpy(fanotify_info_name(info), name->name);
}
static inline void fanotify_info_copy_name2(struct fanotify_info *info,
const struct qstr *name)
{
if (WARN_ON_ONCE(name->len > NAME_MAX))
return;
info->name2_len = name->len;
strcpy(fanotify_info_name2(info), name->name);
}
/*
* Common structure for fanotify events. Concrete structs are allocated in
* fanotify_handle_event() and freed when the information is retrieved by
* userspace. The type of event determines how it was allocated, how it will
* be freed and which concrete struct it may be cast to.
*/
enum fanotify_event_type {
FANOTIFY_EVENT_TYPE_FID, /* fixed length */
FANOTIFY_EVENT_TYPE_FID_NAME, /* variable length */
FANOTIFY_EVENT_TYPE_PATH,
FANOTIFY_EVENT_TYPE_PATH_PERM,
FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */
FANOTIFY_EVENT_TYPE_FS_ERROR, /* struct fanotify_error_event */
__FANOTIFY_EVENT_TYPE_NUM
};
#define FANOTIFY_EVENT_TYPE_BITS \
(ilog2(__FANOTIFY_EVENT_TYPE_NUM - 1) + 1)
#define FANOTIFY_EVENT_HASH_BITS \
(32 - FANOTIFY_EVENT_TYPE_BITS)
struct fanotify_event {
struct fsnotify_event fse;
struct hlist_node merge_list; /* List for hashed merge */
u32 mask;
struct {
unsigned int type : FANOTIFY_EVENT_TYPE_BITS;
unsigned int hash : FANOTIFY_EVENT_HASH_BITS;
};
struct pid *pid;
};
static inline void fanotify_init_event(struct fanotify_event *event,
unsigned int hash, u32 mask)
{
fsnotify_init_event(&event->fse);
INIT_HLIST_NODE(&event->merge_list);
event->hash = hash;
event->mask = mask;
event->pid = NULL;
}
#define FANOTIFY_INLINE_FH(name, size) \
struct { \
struct fanotify_fh (name); \
/* Space for object_fh.buf[] - access with fanotify_fh_buf() */ \
unsigned char _inline_fh_buf[(size)]; \
}
struct fanotify_fid_event {
struct fanotify_event fae;
__kernel_fsid_t fsid;
FANOTIFY_INLINE_FH(object_fh, FANOTIFY_INLINE_FH_LEN);
};
static inline struct fanotify_fid_event *
FANOTIFY_FE(struct fanotify_event *event)
{
return container_of(event, struct fanotify_fid_event, fae);
}
struct fanotify_name_event {
struct fanotify_event fae;
__kernel_fsid_t fsid;
struct fanotify_info info;
};
static inline struct fanotify_name_event *
FANOTIFY_NE(struct fanotify_event *event)
{
return container_of(event, struct fanotify_name_event, fae);
}
struct fanotify_error_event {
struct fanotify_event fae;
s32 error; /* Error reported by the Filesystem. */
u32 err_count; /* Suppressed errors count */
__kernel_fsid_t fsid; /* FSID this error refers to. */
FANOTIFY_INLINE_FH(object_fh, MAX_HANDLE_SZ);
};
static inline struct fanotify_error_event *
FANOTIFY_EE(struct fanotify_event *event)
{
return container_of(event, struct fanotify_error_event, fae);
}
static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
{
if (event->type == FANOTIFY_EVENT_TYPE_FID)
return &FANOTIFY_FE(event)->fsid;
else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
return &FANOTIFY_NE(event)->fsid;
else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
return &FANOTIFY_EE(event)->fsid;
else
return NULL;
}
static inline struct fanotify_fh *fanotify_event_object_fh(
struct fanotify_event *event)
{
if (event->type == FANOTIFY_EVENT_TYPE_FID)
return &FANOTIFY_FE(event)->object_fh;
else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
return fanotify_info_file_fh(&FANOTIFY_NE(event)->info);
else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
return &FANOTIFY_EE(event)->object_fh;
else
return NULL;
}
static inline struct fanotify_info *fanotify_event_info(
struct fanotify_event *event)
{
if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
return &FANOTIFY_NE(event)->info;
else
return NULL;
}
static inline int fanotify_event_object_fh_len(struct fanotify_event *event)
{
struct fanotify_info *info = fanotify_event_info(event);
struct fanotify_fh *fh = fanotify_event_object_fh(event);
if (info)
return info->file_fh_totlen ? fh->len : 0;
else
return fh ? fh->len : 0;
}
static inline int fanotify_event_dir_fh_len(struct fanotify_event *event)
{
struct fanotify_info *info = fanotify_event_info(event);
return info ? fanotify_info_dir_fh_len(info) : 0;
}
static inline int fanotify_event_dir2_fh_len(struct fanotify_event *event)
{
struct fanotify_info *info = fanotify_event_info(event);
return info ? fanotify_info_dir2_fh_len(info) : 0;
}
static inline bool fanotify_event_has_object_fh(struct fanotify_event *event)
{
/* For error events, even zeroed fh are reported. */
if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
return true;
return fanotify_event_object_fh_len(event) > 0;
}
static inline bool fanotify_event_has_dir_fh(struct fanotify_event *event)
{
return fanotify_event_dir_fh_len(event) > 0;
}
static inline bool fanotify_event_has_dir2_fh(struct fanotify_event *event)
{
return fanotify_event_dir2_fh_len(event) > 0;
}
static inline bool fanotify_event_has_any_dir_fh(struct fanotify_event *event)
{
return fanotify_event_has_dir_fh(event) ||
fanotify_event_has_dir2_fh(event);
}
struct fanotify_path_event {
struct fanotify_event fae;
struct path path;
};
static inline struct fanotify_path_event *
FANOTIFY_PE(struct fanotify_event *event)
{
return container_of(event, struct fanotify_path_event, fae);
}
/*
* 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;
struct path path;
unsigned short response; /* userspace answer to the event */
unsigned short state; /* state of the event */
int fd; /* fd we passed to userspace for this event */
};
static inline struct fanotify_perm_event *
FANOTIFY_PERM(struct fanotify_event *event)
{
return container_of(event, struct fanotify_perm_event, fae);
}
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);
}
static inline bool fanotify_is_error_event(u32 mask)
{
return mask & FAN_FS_ERROR;
}
static inline bool fanotify_event_has_path(struct fanotify_event *event)
{
return event->type == FANOTIFY_EVENT_TYPE_PATH ||
event->type == FANOTIFY_EVENT_TYPE_PATH_PERM;
}
static inline struct path *fanotify_event_path(struct fanotify_event *event)
{
if (event->type == FANOTIFY_EVENT_TYPE_PATH)
return &FANOTIFY_PE(event)->path;
else if (event->type == FANOTIFY_EVENT_TYPE_PATH_PERM)
return &FANOTIFY_PERM(event)->path;
else
return NULL;
}
/*
* Use 128 size hash table to speed up events merge.
*/
#define FANOTIFY_HTABLE_BITS (7)
#define FANOTIFY_HTABLE_SIZE (1 << FANOTIFY_HTABLE_BITS)
#define FANOTIFY_HTABLE_MASK (FANOTIFY_HTABLE_SIZE - 1)
/*
* Permission events and overflow event do not get merged - don't hash them.
*/
static inline bool fanotify_is_hashed_event(u32 mask)
{
return !(fanotify_is_perm_event(mask) ||
fsnotify_is_overflow_event(mask));
}
static inline unsigned int fanotify_event_hash_bucket(
struct fsnotify_group *group,
struct fanotify_event *event)
{
return event->hash & FANOTIFY_HTABLE_MASK;
}