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.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fanotify/fanotify.c | 35 +++++++++++++++++++----------------
fs/notify/fanotify/fanotify.h | 20 ++++++++++++++++++++
2 files changed, 39 insertions(+), 16 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index ffad224be014..2b13c79cebc6 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -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);
- dfh = fanotify_info_dir_fh(info);
- info->dir_fh_totlen = fanotify_encode_fh(dfh, id, dir_fh_len, hash, 0);
+ if (dir_fh_len) {
+ dfh = fanotify_info_dir_fh(info);
+ 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;
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index dd23ba659e76..7ac6f9f1e414 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -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)
{
--
2.33.1
