diff options
author | Amir Goldstein <amir73il@gmail.com> | 2020-07-16 11:42:17 +0300 |
---|---|---|
committer | Jan Kara <jack@suse.cz> | 2020-07-27 21:23:37 +0200 |
commit | f454fa610a69b93e7ed4de739e736f988d95c2d2 (patch) | |
tree | 699289ff1b9413920896a3a7fd76f34c183a8528 /fs/notify/fanotify/fanotify.h | |
parent | 6ba8d7107f27c1bde60a80bc5def027979af3e8e (diff) |
fanotify: use struct fanotify_info to parcel the variable size buffer
An fanotify event name is always recorded relative to a dir fh.
Encapsulate the name_len member of fanotify_name_event in a new struct
fanotify_info, which describes the parceling of the variable size
buffer of an fanotify_name_event.
The dir_fh member of fanotify_name_event is renamed to _dir_fh and is not
accessed directly, but via the fanotify_info_dir_fh() accessor.
Although the dir_fh len information is already available in struct
fanotify_fh, we store it also in dif_fh_totlen member of fanotify_info,
including the size of fanotify_fh header, so we know the offset of the
name in the buffer without looking inside the dir_fh.
We also add a file_fh_totlen member to allow packing another file handle
in the variable size buffer after the dir_fh and before the name.
We are going to use that space to store the child fid.
Link: https://lore.kernel.org/r/20200716084230.30611-10-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/notify/fanotify/fanotify.h')
-rw-r--r-- | fs/notify/fanotify/fanotify.h | 91 |
1 files changed, 78 insertions, 13 deletions
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h index 1b2a3bbe6008..5e104fc56abb 100644 --- a/fs/notify/fanotify/fanotify.h +++ b/fs/notify/fanotify/fanotify.h @@ -23,11 +23,29 @@ enum { * 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 { - unsigned char buf[FANOTIFY_INLINE_FH_LEN]; u8 type; u8 len; + u8 pad[2]; + unsigned char buf[FANOTIFY_INLINE_FH_LEN]; +} __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) @@ -37,6 +55,7 @@ static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh) 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 *)); @@ -52,6 +71,56 @@ 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 @@ -96,9 +165,9 @@ FANOTIFY_FE(struct fanotify_event *event) struct fanotify_name_event { struct fanotify_event fae; __kernel_fsid_t fsid; - struct fanotify_fh dir_fh; - u8 name_len; - char name[]; + struct fanotify_info info; + /* Reserve space in info.buf[] - access with fanotify_info_dir_fh() */ + struct fanotify_fh _dir_fh; }; static inline struct fanotify_name_event * @@ -126,11 +195,11 @@ static inline struct fanotify_fh *fanotify_event_object_fh( return NULL; } -static inline struct fanotify_fh *fanotify_event_dir_fh( +static inline struct fanotify_info *fanotify_event_info( struct fanotify_event *event) { if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME) - return &FANOTIFY_NE(event)->dir_fh; + return &FANOTIFY_NE(event)->info; else return NULL; } @@ -142,15 +211,11 @@ static inline int fanotify_event_object_fh_len(struct fanotify_event *event) return fh ? fh->len : 0; } -static inline bool fanotify_event_has_name(struct fanotify_event *event) +static inline int fanotify_event_dir_fh_len(struct fanotify_event *event) { - return event->type == FANOTIFY_EVENT_TYPE_FID_NAME; -} + struct fanotify_info *info = fanotify_event_info(event); -static inline int fanotify_event_name_len(struct fanotify_event *event) -{ - return fanotify_event_has_name(event) ? - FANOTIFY_NE(event)->name_len : 0; + return info ? fanotify_info_dir_fh_len(info) : 0; } struct fanotify_path_event { |