/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/fsnotify_backend.h>
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#include <linux/path.h>
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#include <linux/slab.h>
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#include <linux/exportfs.h>
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extern struct kmem_cache *fanotify_mark_cache;
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extern struct kmem_cache *fanotify_fid_event_cachep;
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extern struct kmem_cache *fanotify_path_event_cachep;
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extern struct kmem_cache *fanotify_perm_event_cachep;
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/* Possible states of the permission event */
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enum {
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FAN_EVENT_INIT,
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FAN_EVENT_REPORTED,
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FAN_EVENT_ANSWERED,
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FAN_EVENT_CANCELED,
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};
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/*
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* 3 dwords are sufficient for most local fs (64bit ino, 32bit generation).
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* fh buf should be dword aligned. On 64bit arch, the ext_buf pointer is
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* stored in either the first or last 2 dwords.
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*/
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#define FANOTIFY_INLINE_FH_LEN (3 << 2)
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#define FANOTIFY_FH_HDR_LEN offsetof(struct fanotify_fh, buf)
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/* Fixed size struct for file handle */
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struct fanotify_fh {
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u8 type;
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u8 len;
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#define FANOTIFY_FH_FLAG_EXT_BUF 1
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u8 flags;
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u8 pad;
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unsigned char buf[];
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} __aligned(4);
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/* Variable size struct for dir file handle + child file handle + name */
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struct fanotify_info {
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/* size of dir_fh/file_fh including fanotify_fh hdr size */
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u8 dir_fh_totlen;
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u8 file_fh_totlen;
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u8 name_len;
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u8 pad;
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unsigned char buf[];
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/*
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* (struct fanotify_fh) dir_fh starts at buf[0]
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* (optional) file_fh starts at buf[dir_fh_totlen]
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* name starts at buf[dir_fh_totlen + file_fh_totlen]
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*/
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} __aligned(4);
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static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh)
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{
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return (fh->flags & FANOTIFY_FH_FLAG_EXT_BUF);
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}
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static inline char **fanotify_fh_ext_buf_ptr(struct fanotify_fh *fh)
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{
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BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN % 4);
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BUILD_BUG_ON(__alignof__(char *) - 4 + sizeof(char *) >
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FANOTIFY_INLINE_FH_LEN);
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return (char **)ALIGN((unsigned long)(fh->buf), __alignof__(char *));
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}
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static inline void *fanotify_fh_ext_buf(struct fanotify_fh *fh)
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{
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return *fanotify_fh_ext_buf_ptr(fh);
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}
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static inline void *fanotify_fh_buf(struct fanotify_fh *fh)
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{
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return fanotify_fh_has_ext_buf(fh) ? fanotify_fh_ext_buf(fh) : fh->buf;
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}
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static inline int fanotify_info_dir_fh_len(struct fanotify_info *info)
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{
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if (!info->dir_fh_totlen ||
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WARN_ON_ONCE(info->dir_fh_totlen < FANOTIFY_FH_HDR_LEN))
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return 0;
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return info->dir_fh_totlen - FANOTIFY_FH_HDR_LEN;
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}
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static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *info)
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{
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BUILD_BUG_ON(offsetof(struct fanotify_info, buf) % 4);
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return (struct fanotify_fh *)info->buf;
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}
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static inline int fanotify_info_file_fh_len(struct fanotify_info *info)
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{
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if (!info->file_fh_totlen ||
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WARN_ON_ONCE(info->file_fh_totlen < FANOTIFY_FH_HDR_LEN))
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return 0;
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return info->file_fh_totlen - FANOTIFY_FH_HDR_LEN;
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}
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static inline struct fanotify_fh *fanotify_info_file_fh(struct fanotify_info *info)
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{
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return (struct fanotify_fh *)(info->buf + info->dir_fh_totlen);
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}
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static inline const char *fanotify_info_name(struct fanotify_info *info)
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{
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return info->buf + info->dir_fh_totlen + info->file_fh_totlen;
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}
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static inline void fanotify_info_init(struct fanotify_info *info)
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{
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info->dir_fh_totlen = 0;
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info->file_fh_totlen = 0;
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info->name_len = 0;
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}
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static inline void fanotify_info_copy_name(struct fanotify_info *info,
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const struct qstr *name)
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{
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info->name_len = name->len;
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strcpy(info->buf + info->dir_fh_totlen + info->file_fh_totlen,
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name->name);
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}
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/*
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* Common structure for fanotify events. Concrete structs are allocated in
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* fanotify_handle_event() and freed when the information is retrieved by
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* userspace. The type of event determines how it was allocated, how it will
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* be freed and which concrete struct it may be cast to.
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*/
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enum fanotify_event_type {
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FANOTIFY_EVENT_TYPE_FID, /* fixed length */
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FANOTIFY_EVENT_TYPE_FID_NAME, /* variable length */
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FANOTIFY_EVENT_TYPE_PATH,
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FANOTIFY_EVENT_TYPE_PATH_PERM,
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FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */
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};
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struct fanotify_event {
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struct fsnotify_event fse;
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u32 mask;
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enum fanotify_event_type type;
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struct pid *pid;
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};
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static inline void fanotify_init_event(struct fanotify_event *event,
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unsigned long id, u32 mask)
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{
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fsnotify_init_event(&event->fse, id);
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event->mask = mask;
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event->pid = NULL;
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}
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struct fanotify_fid_event {
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struct fanotify_event fae;
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__kernel_fsid_t fsid;
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struct fanotify_fh object_fh;
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/* Reserve space in object_fh.buf[] - access with fanotify_fh_buf() */
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unsigned char _inline_fh_buf[FANOTIFY_INLINE_FH_LEN];
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};
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static inline struct fanotify_fid_event *
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FANOTIFY_FE(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_fid_event, fae);
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}
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struct fanotify_name_event {
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struct fanotify_event fae;
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__kernel_fsid_t fsid;
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struct fanotify_info info;
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};
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static inline struct fanotify_name_event *
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FANOTIFY_NE(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_name_event, fae);
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}
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static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
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{
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if (event->type == FANOTIFY_EVENT_TYPE_FID)
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return &FANOTIFY_FE(event)->fsid;
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else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
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return &FANOTIFY_NE(event)->fsid;
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else
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return NULL;
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}
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static inline struct fanotify_fh *fanotify_event_object_fh(
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struct fanotify_event *event)
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{
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if (event->type == FANOTIFY_EVENT_TYPE_FID)
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return &FANOTIFY_FE(event)->object_fh;
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else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
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return fanotify_info_file_fh(&FANOTIFY_NE(event)->info);
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else
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return NULL;
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}
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static inline struct fanotify_info *fanotify_event_info(
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struct fanotify_event *event)
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{
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if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
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return &FANOTIFY_NE(event)->info;
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else
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return NULL;
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}
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static inline int fanotify_event_object_fh_len(struct fanotify_event *event)
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{
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struct fanotify_info *info = fanotify_event_info(event);
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struct fanotify_fh *fh = fanotify_event_object_fh(event);
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if (info)
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return info->file_fh_totlen ? fh->len : 0;
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else
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return fh ? fh->len : 0;
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}
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static inline int fanotify_event_dir_fh_len(struct fanotify_event *event)
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{
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struct fanotify_info *info = fanotify_event_info(event);
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return info ? fanotify_info_dir_fh_len(info) : 0;
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}
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struct fanotify_path_event {
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struct fanotify_event fae;
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struct path path;
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};
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static inline struct fanotify_path_event *
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FANOTIFY_PE(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_path_event, fae);
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}
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/*
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* Structure for permission fanotify events. It gets allocated and freed in
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* fanotify_handle_event() since we wait there for user response. When the
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* information is retrieved by userspace the structure is moved from
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* group->notification_list to group->fanotify_data.access_list to wait for
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* user response.
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*/
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struct fanotify_perm_event {
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struct fanotify_event fae;
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struct path path;
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unsigned short response; /* userspace answer to the event */
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unsigned short state; /* state of the event */
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int fd; /* fd we passed to userspace for this event */
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};
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static inline struct fanotify_perm_event *
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FANOTIFY_PERM(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_perm_event, fae);
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}
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static inline bool fanotify_is_perm_event(u32 mask)
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{
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return IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS) &&
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mask & FANOTIFY_PERM_EVENTS;
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}
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static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)
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{
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return container_of(fse, struct fanotify_event, fse);
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}
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static inline bool fanotify_event_has_path(struct fanotify_event *event)
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{
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return event->type == FANOTIFY_EVENT_TYPE_PATH ||
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event->type == FANOTIFY_EVENT_TYPE_PATH_PERM;
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}
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static inline struct path *fanotify_event_path(struct fanotify_event *event)
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{
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if (event->type == FANOTIFY_EVENT_TYPE_PATH)
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return &FANOTIFY_PE(event)->path;
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else if (event->type == FANOTIFY_EVENT_TYPE_PATH_PERM)
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return &FANOTIFY_PERM(event)->path;
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else
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return NULL;
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}
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