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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_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 file_fh_totlen;
- u8 name_len;
- u8 pad;
- unsigned char buf[];
- /*
- * (struct fanotify_fh) dir_fh starts at buf[0]
- * (optional) file_fh starts at buf[dir_fh_totlen]
- * name starts at buf[dir_fh_totlen + file_fh_totlen]
- */
- } __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 *)info->buf;
- }
- 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 *)(info->buf + info->dir_fh_totlen);
- }
- static inline const char *fanotify_info_name(struct fanotify_info *info)
- {
- return info->buf + info->dir_fh_totlen + info->file_fh_totlen;
- }
- static inline void fanotify_info_init(struct fanotify_info *info)
- {
- info->dir_fh_totlen = 0;
- info->file_fh_totlen = 0;
- info->name_len = 0;
- }
- static inline void fanotify_info_copy_name(struct fanotify_info *info,
- const struct qstr *name)
- {
- info->name_len = name->len;
- strcpy(info->buf + info->dir_fh_totlen + info->file_fh_totlen,
- 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 */
- };
- struct fanotify_event {
- struct fsnotify_event fse;
- u32 mask;
- enum fanotify_event_type type;
- struct pid *pid;
- };
- static inline void fanotify_init_event(struct fanotify_event *event,
- unsigned long id, u32 mask)
- {
- fsnotify_init_event(&event->fse, id);
- event->mask = mask;
- event->pid = NULL;
- }
- struct fanotify_fid_event {
- struct fanotify_event fae;
- __kernel_fsid_t fsid;
- struct fanotify_fh object_fh;
- /* Reserve space in object_fh.buf[] - access with fanotify_fh_buf() */
- unsigned char _inline_fh_buf[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);
- }
- 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
- 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
- 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;
- }
- 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_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;
- }
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