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.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fanotify/fanotify.h | 2 +
fs/notify/fanotify/fanotify_user.c | 63 +++++++++++++++++++++++++-----
include/linux/fanotify.h | 5 ++-
include/uapi/linux/fanotify.h | 8 ++++
4 files changed, 67 insertions(+), 11 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 80e0ec95b113..c54d0b404373 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -499,6 +499,8 @@ static inline unsigned int fanotify_mark_user_flags(struct fsnotify_mark *mark)
mflags |= FAN_MARK_IGNORED_SURV_MODIFY;
if (mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)
mflags |= FAN_MARK_EVICTABLE;
+ if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORE_FLAGS)
+ mflags |= FAN_MARK_IGNORE;
return mflags;
}
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 6781d46cd37c..006be1ca048a 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1009,7 +1009,7 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
mask &= ~umask;
spin_lock(&fsn_mark->lock);
oldmask = fsnotify_calc_mask(fsn_mark);
- if (!(flags & FAN_MARK_IGNORED_MASK)) {
+ if (!(flags & FANOTIFY_MARK_IGNORE_BITS)) {
fsn_mark->mask &= ~mask;
} else {
fsn_mark->ignore_mask &= ~mask;
@@ -1085,15 +1085,24 @@ static bool fanotify_mark_update_flags(struct fsnotify_mark *fsn_mark,
unsigned int fan_flags)
{
bool want_iref = !(fan_flags & FAN_MARK_EVICTABLE);
+ unsigned int ignore = fan_flags & FANOTIFY_MARK_IGNORE_BITS;
bool recalc = false;
+ /*
+ * When using FAN_MARK_IGNORE for the first time, mark starts using
+ * independent event flags in ignore mask. After that, trying to
+ * update the ignore mask with the old FAN_MARK_IGNORED_MASK API
+ * will result in EEXIST error.
+ */
+ if (ignore == FAN_MARK_IGNORE)
+ fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORE_FLAGS;
+
/*
* Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to
* the removal of the FS_MODIFY bit in calculated mask if it was set
* because of an ignore mask that is now going to survive FS_MODIFY.
*/
- if ((fan_flags & FAN_MARK_IGNORED_MASK) &&
- (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
+ if (ignore && (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
!(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) {
fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
if (!(fsn_mark->mask & FS_MODIFY))
@@ -1120,7 +1129,7 @@ static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
bool recalc;
spin_lock(&fsn_mark->lock);
- if (!(fan_flags & FAN_MARK_IGNORED_MASK))
+ if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS))
fsn_mark->mask |= mask;
else
fsn_mark->ignore_mask |= mask;
@@ -1197,6 +1206,24 @@ static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark,
!(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF))
return -EEXIST;
+ /*
+ * New ignore mask semantics cannot be downgraded to old semantics.
+ */
+ if (fan_flags & FAN_MARK_IGNORED_MASK &&
+ fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORE_FLAGS)
+ return -EEXIST;
+
+ /*
+ * An ignore mask that survives modify could never be downgraded to not
+ * survive modify. With new FAN_MARK_IGNORE semantics we make that rule
+ * explicit and return an error when trying to update the ignore mask
+ * without the original FAN_MARK_IGNORED_SURV_MODIFY value.
+ */
+ if (fan_flags & FAN_MARK_IGNORE &&
+ !(fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
+ fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
+ return -EEXIST;
+
return 0;
}
@@ -1231,7 +1258,8 @@ static int fanotify_add_mark(struct fsnotify_group *group,
* Error events are pre-allocated per group, only if strictly
* needed (i.e. FAN_FS_ERROR was requested).
*/
- if (!(fan_flags & FAN_MARK_IGNORED_MASK) && (mask & FAN_FS_ERROR)) {
+ if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS) &&
+ (mask & FAN_FS_ERROR)) {
ret = fanotify_group_init_error_pool(group);
if (ret)
goto out;
@@ -1275,7 +1303,7 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
* an ignore mask, unless that ignore mask is supposed to survive
* modification changes anyway.
*/
- if ((flags & FAN_MARK_IGNORED_MASK) &&
+ if ((flags & FANOTIFY_MARK_IGNORE_BITS) &&
!(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
inode_is_open_for_write(inode))
return 0;
@@ -1531,7 +1559,8 @@ static int fanotify_events_supported(struct fsnotify_group *group,
unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
/* Strict validation of events in non-dir inode mask with v5.17+ APIs */
bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) ||
- (mask & FAN_RENAME);
+ (mask & FAN_RENAME) ||
+ (flags & FAN_MARK_IGNORE);
/*
* Some filesystems such as 'proc' acquire unusual locks when opening
@@ -1569,7 +1598,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS;
unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS;
- bool ignore = flags & FAN_MARK_IGNORED_MASK;
+ unsigned int ignore = flags & FANOTIFY_MARK_IGNORE_BITS;
unsigned int obj_type, fid_mode;
u32 umask = 0;
int ret;
@@ -1618,12 +1647,19 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
if (mask & ~valid_mask)
return -EINVAL;
+
+ /* We don't allow FAN_MARK_IGNORE & FAN_MARK_IGNORED_MASK together */
+ if (ignore == (FAN_MARK_IGNORE | FAN_MARK_IGNORED_MASK))
+ return -EINVAL;
+
/*
* Event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) have no effect with
* FAN_MARK_IGNORED_MASK.
*/
- if (ignore)
+ if (ignore == FAN_MARK_IGNORED_MASK) {
mask &= ~FANOTIFY_EVENT_FLAGS;
+ umask = FANOTIFY_EVENT_FLAGS;
+ }
f = fdget(fanotify_fd);
if (unlikely(!f.file))
@@ -1727,6 +1763,13 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
else
mnt = path.mnt;
+ ret = mnt ? -EINVAL : -EISDIR;
+ /* FAN_MARK_IGNORE requires SURV_MODIFY for sb/mount/dir marks */
+ if (mark_cmd == FAN_MARK_ADD && ignore == FAN_MARK_IGNORE &&
+ (mnt || S_ISDIR(inode->i_mode)) &&
+ !(flags & FAN_MARK_IGNORED_SURV_MODIFY))
+ goto path_put_and_out;
+
/* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */
if (mnt || !S_ISDIR(inode->i_mode)) {
mask &= ~FAN_EVENT_ON_CHILD;
@@ -1819,7 +1862,7 @@ static int __init fanotify_user_setup(void)
BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS);
BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 12);
- BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 10);
+ BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11);
fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
SLAB_PANIC|SLAB_ACCOUNT);
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index a7207f092fd1..8ad743def6f3 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -62,11 +62,14 @@
#define FANOTIFY_MARK_CMD_BITS (FAN_MARK_ADD | FAN_MARK_REMOVE | \
FAN_MARK_FLUSH)
+#define FANOTIFY_MARK_IGNORE_BITS (FAN_MARK_IGNORED_MASK | \
+ FAN_MARK_IGNORE)
+
#define FANOTIFY_MARK_FLAGS (FANOTIFY_MARK_TYPE_BITS | \
FANOTIFY_MARK_CMD_BITS | \
+ FANOTIFY_MARK_IGNORE_BITS | \
FAN_MARK_DONT_FOLLOW | \
FAN_MARK_ONLYDIR | \
- FAN_MARK_IGNORED_MASK | \
FAN_MARK_IGNORED_SURV_MODIFY | \
FAN_MARK_EVICTABLE)
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 |\
--
2.25.1
