fanotify: record old and new parent and name in FAN_RENAME event

In the special case of FAN_RENAME event, we record both the old
and new parent and name.

Link: https://lore.kernel.org/r/20211129201537.1932819-9-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 5f184b2..db81eab 100644 (file)
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -592,21 +592,28 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *dir,
                                                        __kernel_fsid_t *fsid,
                                                        const struct qstr *name,
                                                        struct inode *child,
+                                                       struct dentry *moved,
                                                        unsigned int *hash,
                                                        gfp_t gfp)
 {
        struct fanotify_name_event *fne;
        struct fanotify_info *info;
        struct fanotify_fh *dfh, *ffh;
+       struct inode *dir2 = moved ? d_inode(moved->d_parent) : NULL;
+       const struct qstr *name2 = moved ? &moved->d_name : NULL;
        unsigned int dir_fh_len = fanotify_encode_fh_len(dir);
+       unsigned int dir2_fh_len = fanotify_encode_fh_len(dir2);
        unsigned int child_fh_len = fanotify_encode_fh_len(child);
        unsigned long name_len = name ? name->len : 0;
+       unsigned long name2_len = name2 ? name2->len : 0;
        unsigned int len, size;
 
        /* Reserve terminating null byte even for empty name */
-       size = sizeof(*fne) + name_len + 1;
+       size = sizeof(*fne) + name_len + name2_len + 2;
        if (dir_fh_len)
                size += FANOTIFY_FH_HDR_LEN + dir_fh_len;
+       if (dir2_fh_len)
+               size += FANOTIFY_FH_HDR_LEN + dir2_fh_len;
        if (child_fh_len)
                size += FANOTIFY_FH_HDR_LEN + child_fh_len;
        fne = kmalloc(size, gfp);
@@ -623,6 +630,11 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *dir,
                len = fanotify_encode_fh(dfh, dir, dir_fh_len, hash, 0);
                fanotify_info_set_dir_fh(info, len);
        }
+       if (dir2_fh_len) {
+               dfh = fanotify_info_dir2_fh(info);
+               len = fanotify_encode_fh(dfh, dir2, dir2_fh_len, hash, 0);
+               fanotify_info_set_dir2_fh(info, len);
+       }
        if (child_fh_len) {
                ffh = fanotify_info_file_fh(info);
                len = fanotify_encode_fh(ffh, child, child_fh_len, hash, 0);
@@ -632,11 +644,22 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *dir,
                fanotify_info_copy_name(info, name);
                *hash ^= full_name_hash((void *)name_len, name->name, name_len);
        }
+       if (name2_len) {
+               fanotify_info_copy_name2(info, name2);
+               *hash ^= full_name_hash((void *)name2_len, name2->name,
+                                       name2_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));
 
+       if (dir2_fh_len) {
+               pr_debug("%s: dir2_fh_len=%u name2_len=%u name2='%.*s'\n",
+                        __func__, dir2_fh_len, info->name2_len,
+                        info->name2_len, fanotify_info_name2(info));
+       }
+
        return &fne->fae;
 }
 
@@ -692,6 +715,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
        struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir);
        const struct path *path = fsnotify_data_path(data, data_type);
        struct mem_cgroup *old_memcg;
+       struct dentry *moved = NULL;
        struct inode *child = NULL;
        bool name_event = false;
        unsigned int hash = 0;
@@ -727,6 +751,15 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
                } else if ((mask & ALL_FSNOTIFY_DIRENT_EVENTS) || !ondir) {
                        name_event = true;
                }
+
+               /*
+                * In the special case of FAN_RENAME event, we record both
+                * old and new parent+name.
+                * 'dirid' and 'file_name' are the old parent+name and
+                * 'moved' has the new parent+name.
+                */
+               if (mask & FAN_RENAME)
+                       moved = fsnotify_data_dentry(data, data_type);
        }
 
        /*
@@ -748,9 +781,9 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
        } else if (fanotify_is_error_event(mask)) {
                event = fanotify_alloc_error_event(group, fsid, data,
                                                   data_type, &hash);
-       } else if (name_event && (file_name || child)) {
-               event = fanotify_alloc_name_event(id, fsid, file_name, child,
-                                                 &hash, gfp);
+       } else if (name_event && (file_name || moved || child)) {
+               event = fanotify_alloc_name_event(dirid, fsid, file_name, child,
+                                                 moved, &hash, gfp);
        } else if (fid_mode) {
                event = fanotify_alloc_fid_event(id, fsid, &hash, gfp);
        } else {
@@ -860,6 +893,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
        BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC);
        BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
        BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR);
+       BUILD_BUG_ON(FAN_RENAME != FS_RENAME);
 
        BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20);
 

diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index 60f7363..9d0e2dc 100644 (file)
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -28,6 +28,8 @@
 
 #define FAN_EVENT_ON_CHILD     0x08000000      /* Interested in child events */
 
+#define FAN_RENAME             0x10000000      /* File was renamed */
+
 #define FAN_ONDIR              0x40000000      /* Event occurred against dir */
 
 /* helper events */