From 94dfc73e7cf4a31da66b8843f0b9283ddd6b8381 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Wed, 6 Apr 2022 19:36:51 -0500 Subject: treewide: uapi: Replace zero-length arrays with flexible-array members MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. This code was transformed with the help of Coccinelle: (linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch) @@ identifier S, member, array; type T1, T2; @@ struct S { ... T1 member; T2 array[ - 0 ]; }; -fstrict-flex-arrays=3 is coming and we need to land these changes to prevent issues like these in the short future: ../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0, but the source string has length 2 (including NUL byte) [-Wfortify-source] strcpy(de3->name, "."); ^ Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If this breaks anything, we can use a union with a new member name. [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays Link: https://github.com/KSPP/linux/issues/78 Build-tested-by: kernel test robot Link: https://lore.kernel.org/lkml/62b675ec.wKX6AOZ6cbE71vtF%25lkp@intel.com/ Acked-by: Dan Williams # For ndctl.h Signed-off-by: Gustavo A. R. Silva --- include/uapi/linux/fanotify.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/uapi/linux/fanotify.h') diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index f1f89132d60e..197df344307d 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -162,7 +162,7 @@ struct fanotify_event_info_fid { * Following is an opaque struct file_handle that can be passed as * an argument to open_by_handle_at(2). */ - unsigned char handle[0]; + unsigned char handle[]; }; /* -- cgit v1.2.3 From e252f2ed1c8c6c3884ab5dd34e003ed21f1fe6e0 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Wed, 29 Jun 2022 17:42:10 +0300 Subject: fanotify: introduce FAN_MARK_IGNORE This flag is a new way to configure ignore mask which allows adding and removing the event flags FAN_ONDIR and FAN_EVENT_ON_CHILD in ignore mask. The legacy FAN_MARK_IGNORED_MASK flag would always ignore events on directories and would ignore events on children depending on whether the FAN_EVENT_ON_CHILD flag was set in the (non ignored) mask. FAN_MARK_IGNORE can be used to ignore events on children without setting FAN_EVENT_ON_CHILD in the mark's mask and will not ignore events on directories unconditionally, only when FAN_ONDIR is set in ignore mask. The new behavior is non-downgradable. After calling fanotify_mark() with FAN_MARK_IGNORE once, calling fanotify_mark() with FAN_MARK_IGNORED_MASK on the same object will return EEXIST error. Setting the event flags with FAN_MARK_IGNORE on a non-dir inode mark has no meaning and will return ENOTDIR error. The meaning of FAN_MARK_IGNORED_SURV_MODIFY is preserved with the new FAN_MARK_IGNORE flag, but with a few semantic differences: 1. FAN_MARK_IGNORED_SURV_MODIFY is required for filesystem and mount marks and on an inode mark on a directory. Omitting this flag will return EINVAL or EISDIR error. 2. An ignore mask on a non-directory inode that survives modify could never be downgraded to an ignore mask that does not survive modify. With new FAN_MARK_IGNORE semantics we make that rule explicit - trying to update a surviving ignore mask without the flag FAN_MARK_IGNORED_SURV_MODIFY will return EEXIST error. The conveniene macro FAN_MARK_IGNORE_SURV is added for (FAN_MARK_IGNORE | FAN_MARK_IGNORED_SURV_MODIFY), because the common case should use short constant names. Link: https://lore.kernel.org/r/20220629144210.2983229-4-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- include/uapi/linux/fanotify.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/uapi/linux/fanotify.h') diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index f1f89132d60e..d8536d77fea1 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -83,12 +83,20 @@ #define FAN_MARK_FLUSH 0x00000080 /* FAN_MARK_FILESYSTEM is 0x00000100 */ #define FAN_MARK_EVICTABLE 0x00000200 +/* This bit is mutually exclusive with FAN_MARK_IGNORED_MASK bit */ +#define FAN_MARK_IGNORE 0x00000400 /* These are NOT bitwise flags. Both bits can be used togther. */ #define FAN_MARK_INODE 0x00000000 #define FAN_MARK_MOUNT 0x00000010 #define FAN_MARK_FILESYSTEM 0x00000100 +/* + * Convenience macro - FAN_MARK_IGNORE requires FAN_MARK_IGNORED_SURV_MODIFY + * for non-inode mark types. + */ +#define FAN_MARK_IGNORE_SURV (FAN_MARK_IGNORE | FAN_MARK_IGNORED_SURV_MODIFY) + /* Deprecated - do not use this in programs and do not add new flags here! */ #define FAN_ALL_MARK_FLAGS (FAN_MARK_ADD |\ FAN_MARK_REMOVE |\ -- cgit v1.2.3