| Message ID | fc0035bf78ca47e813f1fb603163af0225c491c7.1723144881.git.josef@toxicpanda.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fanotify: add pre-content hooks | expand |
On Thu, Aug 08, 2024 at 03:27:07PM GMT, Josef Bacik wrote: > From: Amir Goldstein <amir73il@gmail.com> > > Generate FAN_PRE_MODIFY permission event from fsnotify_file_perm() > pre-write hook to notify fanotify listeners on an intent to make > modification to a file. > > Like FAN_PRE_ACCESS, it is only allowed with FAN_CLASS_PRE_CONTENT > and unlike FAN_MODIFY, it is only allowed on regular files. > > Like FAN_PRE_ACCESS, it is generated without sb_start_write() held, > so it is safe to perform filesystem modifications in the context of > event handler. > > This pre-content event is meant to be used by hierarchical storage > managers that want to fill the content of files on first write access. > > Signed-off-by: Amir Goldstein <amir73il@gmail.com> > --- Reviewed-by: Christian Brauner <brauner@kernel.org>
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 7dac8e4486df..b163594843f5 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -911,8 +911,9 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask, BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR); BUILD_BUG_ON(FAN_RENAME != FS_RENAME); BUILD_BUG_ON(FAN_PRE_ACCESS != FS_PRE_ACCESS); + BUILD_BUG_ON(FAN_PRE_MODIFY != FS_PRE_MODIFY); - BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 22); + BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 23); mask = fanotify_group_event_mask(group, iter_info, &match_mask, mask, data, data_type, dir); diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index c294849e474f..3a7101544f30 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1673,6 +1673,8 @@ static int fanotify_events_supported(struct fsnotify_group *group, if (mask & FANOTIFY_PRE_CONTENT_EVENTS) { if (!is_dir && !d_is_reg(path->dentry)) return -EINVAL; + if (is_dir && mask & FAN_PRE_MODIFY) + return -EISDIR; } return 0; diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index 5c811baf44d2..ae6cb2688d52 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -92,7 +92,8 @@ #define FANOTIFY_CONTENT_PERM_EVENTS (FAN_OPEN_PERM | FAN_OPEN_EXEC_PERM | \ FAN_ACCESS_PERM) /* Pre-content events can be used to fill file content */ -#define FANOTIFY_PRE_CONTENT_EVENTS (FAN_PRE_ACCESS) +#define FANOTIFY_PRE_CONTENT_EVENTS (FAN_PRE_ACCESS | FAN_PRE_MODIFY) +#define FANOTIFY_PRE_MODIFY_EVENTS (FAN_PRE_MODIFY) /* Events that require a permission response from user */ #define FANOTIFY_PERM_EVENTS (FANOTIFY_CONTENT_PERM_EVENTS | \ diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index bcada21a3a2e..ac00fad66416 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -27,6 +27,7 @@ #define FAN_OPEN_EXEC_PERM 0x00040000 /* File open/exec in perm check */ #define FAN_PRE_ACCESS 0x00080000 /* Pre-content access hook */ +#define FAN_PRE_MODIFY 0x00100000 /* Pre-content modify hook */ #define FAN_EVENT_ON_CHILD 0x08000000 /* Interested in child events */