Commit 1a9515ac authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fanotify: use helpers to parcel fanotify_info buffer 

fanotify_info buffer is parceled into variable sized records, so the
records must be written in order: dir_fh, file_fh, name.

Use helpers to assert that order and make fanotify_alloc_name_event()
a bit more generic to allow empty dir_fh record and to allow expanding
to more records (i.e. name2) soon.

Link: https://lore.kernel.org/r/20211129201537.1932819-7-amir73il@gmail.com


Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 2d9374f0

fs/notify/fanotify/fanotify.c

+19 −16
Original line number Diff line number Diff line
@@ -576,7 +576,7 @@ static struct fanotify_event *fanotify_alloc_fid_event(struct inode *id, 
	return &ffe->fae;

}



static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,

static struct fanotify_event *fanotify_alloc_name_event(struct inode *dir,

							__kernel_fsid_t *fsid,

							const struct qstr *name,

							struct inode *child,
@@ -586,15 +586,17 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *id, 
	struct fanotify_name_event *fne;

	struct fanotify_info *info;

	struct fanotify_fh *dfh, *ffh;

	unsigned int dir_fh_len = fanotify_encode_fh_len(id);

	unsigned int dir_fh_len = fanotify_encode_fh_len(dir);

	unsigned int child_fh_len = fanotify_encode_fh_len(child);

	unsigned int size;

	unsigned long name_len = name ? name->len : 0;

	unsigned int len, size;



	size = sizeof(*fne) + FANOTIFY_FH_HDR_LEN + dir_fh_len;

	/* Reserve terminating null byte even for empty name */

	size = sizeof(*fne) + name_len + 1;

	if (dir_fh_len)

		size += FANOTIFY_FH_HDR_LEN + dir_fh_len;

	if (child_fh_len)

		size += FANOTIFY_FH_HDR_LEN + child_fh_len;

	if (name)

		size += name->len + 1;

	fne = kmalloc(size, gfp);

	if (!fne)

		return NULL;
@@ -604,22 +606,23 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *id, 
	*hash ^= fanotify_hash_fsid(fsid);

	info = &fne->info;

	fanotify_info_init(info);

	if (dir_fh_len) {

		dfh = fanotify_info_dir_fh(info);

	info->dir_fh_totlen = fanotify_encode_fh(dfh, id, dir_fh_len, hash, 0);

		len = fanotify_encode_fh(dfh, dir, dir_fh_len, hash, 0);

		fanotify_info_set_dir_fh(info, len);

	}

	if (child_fh_len) {

		ffh = fanotify_info_file_fh(info);

		info->file_fh_totlen = fanotify_encode_fh(ffh, child,

							child_fh_len, hash, 0);

		len = fanotify_encode_fh(ffh, child, child_fh_len, hash, 0);

		fanotify_info_set_file_fh(info, len);

	}

	if (name) {

		long salt = name->len;



	if (name_len) {

		fanotify_info_copy_name(info, name);

		*hash ^= full_name_hash((void *)salt, name->name, name->len);

		*hash ^= full_name_hash((void *)name_len, name->name, name_len);

	}



	pr_debug("%s: ino=%lu size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n",

		 __func__, id->i_ino, size, dir_fh_len, child_fh_len,

	pr_debug("%s: size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n",

		 __func__, size, dir_fh_len, child_fh_len,

		 info->name_len, info->name_len, fanotify_info_name(info));



	return &fne->fae;

fs/notify/fanotify/fanotify.h

+20 −0
Original line number Diff line number Diff line
@@ -138,6 +138,26 @@ static inline void fanotify_info_init(struct fanotify_info *info) 
	info->name_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->file_fh_totlen > 0) ||

	    WARN_ON_ONCE(info->name_len > 0))

		return;



	info->dir_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))

		return;



	info->file_fh_totlen = totlen;

}



static inline void fanotify_info_copy_name(struct fanotify_info *info,

					   const struct qstr *name)

{