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Date: Thu, 20 May 2021 22:41:31 -0400
From: Gabriel Krisman Bertazi <krisman@...labora.com>
To: amir73il@...il.com
Cc: Gabriel Krisman Bertazi <krisman@...labora.com>,
kernel@...labora.com, "Darrick J . Wong" <djwong@...nel.org>,
Theodore Ts'o <tytso@....edu>,
Dave Chinner <david@...morbit.com>, jack@...e.com,
dhowells@...hat.com, khazhy@...gle.com,
linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: [PATCH 08/11] fanotify: Introduce FAN_ERROR event
The FAN_ERROR event is used by filesystem wide monitoring tools to
receive notifications of type FS_ERROR_EVENT, emited by filesystems when
a problem is detected. The error notification includes a generic error
descriptor.
Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>
Changes since v1:
- Pass dentry to fanotify_check_fsid (Amir)
- FANOTIFY_EVENT_TYPE_ERROR -> FANOTIFY_EVENT_TYPE_FS_ERROR
- Merge previous patch into it
- Use a single slot
---
fs/notify/fanotify/fanotify.c | 74 ++++++++++++++++-
fs/notify/fanotify/fanotify.h | 28 ++++++-
fs/notify/fanotify/fanotify_user.c | 123 ++++++++++++++++++++++++++---
include/linux/fanotify.h | 6 +-
include/uapi/linux/fanotify.h | 10 +++
5 files changed, 225 insertions(+), 16 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 34e2ee759b39..197291a8c41d 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -269,7 +269,7 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
pr_debug("%s: report_mask=%x mask=%x data=%p data_type=%d\n",
__func__, iter_info->report_mask, event_mask, data, data_type);
- if (!fid_mode) {
+ if (!fid_mode && data_type != FSNOTIFY_EVENT_ERROR) {
/* Do we have path to open a file descriptor? */
if (!path)
return 0;
@@ -657,6 +657,51 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
return event;
}
+static void fanotify_init_error_event(struct fanotify_error_event *event,
+ __kernel_fsid_t fsid,
+ const struct fs_error_report *report)
+{
+ event->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
+ event->err_count = 1;
+ event->fsid = fsid;
+ event->error = report->error;
+ event->ino = (report->inode) ? report->inode->i_ino : 0;
+}
+
+static int fanotify_queue_error_event(struct fsnotify_iter_info *iter_info,
+ struct fsnotify_group *group,
+ __kernel_fsid_t fsid,
+ const struct fs_error_report *report)
+{
+ struct fanotify_mark *mark;
+ int type;
+ int ret = -ENOMEM;
+
+ fsnotify_foreach_obj_type(type) {
+ if (!fsnotify_iter_should_report_type(iter_info, type))
+ continue;
+ mark = FANOTIFY_MARK(iter_info->marks[type]);
+ }
+
+ spin_lock(&mark->fsn_mark.lock);
+ if (mark->error_event) {
+ if (list_empty(&mark->error_event->fae.fse.list)) {
+ fsnotify_get_mark(&mark->fsn_mark);
+ fanotify_init_error_event(mark->error_event, fsid, report);
+ ret = fsnotify_add_event(group, &mark->error_event->fae.fse,
+ NULL, NULL);
+ if (ret)
+ fsnotify_put_mark(&mark->fsn_mark);
+ } else {
+ mark->error_event->err_count++;
+ ret = 0;
+ }
+ }
+ spin_unlock(&mark->fsn_mark.lock);
+
+ return ret;
+}
+
/*
* Get cached fsid of the filesystem containing the object from any connector.
* All connectors are supposed to have the same fsid, but we do not verify that
@@ -738,8 +783,9 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC);
BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
+ BUILD_BUG_ON(FAN_ERROR != FS_ERROR);
- BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
+ BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20);
mask = fanotify_group_event_mask(group, iter_info, mask, data,
data_type, dir);
@@ -757,13 +803,20 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
return 0;
}
- if (FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS)) {
+ if (FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS) || fanotify_is_error_event(mask)) {
fsid = fanotify_get_fsid(iter_info);
/* Racing with mark destruction or creation? */
if (!fsid.val[0] && !fsid.val[1])
return 0;
}
+ if (fanotify_is_error_event(mask)) {
+ ret = fanotify_queue_error_event(iter_info, group, fsid, data);
+ if (ret)
+ fsnotify_queue_overflow(group);
+ goto finish;
+ }
+
event = fanotify_alloc_event(group, mask, data, data_type, dir,
file_name, &fsid);
ret = -ENOMEM;
@@ -833,6 +886,17 @@ static void fanotify_free_name_event(struct fanotify_event *event)
kfree(FANOTIFY_NE(event));
}
+static void fanotify_free_error_event(struct fanotify_event *event)
+{
+ /*
+ * Just drop the reference acquired by
+ * fanotify_queue_error_event.
+ *
+ * The actual memory is freed with the mark.
+ */
+ fsnotify_put_mark(&(FANOTIFY_EE(event)->mark->fsn_mark));
+}
+
static void fanotify_free_event(struct fsnotify_event *fsn_event)
{
struct fanotify_event *event;
@@ -855,6 +919,9 @@ static void fanotify_free_event(struct fsnotify_event *fsn_event)
case FANOTIFY_EVENT_TYPE_OVERFLOW:
kfree(event);
break;
+ case FANOTIFY_EVENT_TYPE_FS_ERROR:
+ fanotify_free_error_event(event);
+ break;
default:
WARN_ON_ONCE(1);
}
@@ -871,6 +938,7 @@ static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
{
struct fanotify_mark *mark = FANOTIFY_MARK(fsn_mark);
+ kfree(mark->error_event);
kmem_cache_free(fanotify_mark_cache, mark);
}
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index a399c5e2615d..ebe9e593dfbf 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -151,6 +151,7 @@ enum fanotify_event_type {
FANOTIFY_EVENT_TYPE_PATH,
FANOTIFY_EVENT_TYPE_PATH_PERM,
FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */
+ FANOTIFY_EVENT_TYPE_FS_ERROR, /* struct fanotify_error_event */
__FANOTIFY_EVENT_TYPE_NUM
};
@@ -206,12 +207,31 @@ FANOTIFY_NE(struct fanotify_event *event)
return container_of(event, struct fanotify_name_event, fae);
}
+struct fanotify_error_event {
+ struct fanotify_event fae;
+ __kernel_fsid_t fsid;
+ unsigned long ino;
+ int error;
+ u32 err_count;
+
+ /* Back reference to the mark this error refers to. */
+ struct fanotify_mark *mark;
+};
+
+static inline struct fanotify_error_event *
+FANOTIFY_EE(struct fanotify_event *event)
+{
+ return container_of(event, struct fanotify_error_event, fae);
+}
+
static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
{
if (event->type == FANOTIFY_EVENT_TYPE_FID)
return &FANOTIFY_FE(event)->fsid;
else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
return &FANOTIFY_NE(event)->fsid;
+ else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
+ return &FANOTIFY_EE(event)->fsid;
else
return NULL;
}
@@ -297,6 +317,11 @@ static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)
return container_of(fse, struct fanotify_event, fse);
}
+static inline bool fanotify_is_error_event(u32 mask)
+{
+ return mask & FANOTIFY_ERROR_EVENTS;
+}
+
static inline bool fanotify_event_has_path(struct fanotify_event *event)
{
return event->type == FANOTIFY_EVENT_TYPE_PATH ||
@@ -325,7 +350,8 @@ static inline struct path *fanotify_event_path(struct fanotify_event *event)
*/
static inline bool fanotify_is_hashed_event(u32 mask)
{
- return !fanotify_is_perm_event(mask) && !(mask & FS_Q_OVERFLOW);
+ return (!fanotify_is_perm_event(mask) && !fanotify_is_error_event(mask)
+ && !(mask & FS_Q_OVERFLOW));
}
static inline unsigned int fanotify_event_hash_bucket(
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 00210535a78e..ea9b9f8f7c21 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -106,6 +106,8 @@ struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
#define FANOTIFY_EVENT_ALIGN 4
#define FANOTIFY_INFO_HDR_LEN \
(sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle))
+#define FANOTIFY_INFO_ERROR_LEN \
+ (sizeof(struct fanotify_event_info_error))
static int fanotify_fid_info_len(int fh_len, int name_len)
{
@@ -126,6 +128,9 @@ static size_t fanotify_event_len(struct fanotify_event *event,
int fh_len;
int dot_len = 0;
+ if (fanotify_is_error_event(event->mask))
+ return event_len + FANOTIFY_INFO_ERROR_LEN;
+
if (!fid_mode)
return event_len;
@@ -149,6 +154,30 @@ static size_t fanotify_event_len(struct fanotify_event *event,
return event_len;
}
+static struct fanotify_event *fanotify_dequeue_error_event(struct fsnotify_group *group,
+ struct fanotify_event *event,
+ struct fanotify_error_event *error_event)
+{
+ struct fsnotify_mark *mark = &(FANOTIFY_EE(event)->mark->fsn_mark);
+ /*
+ * In order to avoid missing an error count update, the
+ * queued event is de-queued and duplicated to an
+ * in-stack fanotify_error_event while still inside
+ * mark->lock. Once the event is dequeued, it can be
+ * immediately re-used for a new event.
+ *
+ * The ownership of the mark reference is dropped later
+ * by destroy_event.
+ */
+ spin_lock(&mark->lock);
+ memcpy(error_event, FANOTIFY_EE(event), sizeof(*error_event));
+ fsnotify_init_event(&error_event->fae.fse);
+ fsnotify_remove_queued_event(group, &event->fse);
+ spin_unlock(&mark->lock);
+
+ return &error_event->fae;
+}
+
/*
* Remove an hashed event from merge hash table.
*/
@@ -173,7 +202,8 @@ static void fanotify_unhash_event(struct fsnotify_group *group,
* updated accordingly.
*/
static struct fanotify_event *get_one_event(struct fsnotify_group *group,
- size_t count)
+ size_t count,
+ struct fanotify_error_event *error_event)
{
size_t event_size;
struct fanotify_event *event = NULL;
@@ -197,9 +227,14 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
/*
* Held the notification_lock the whole time, so this is the
- * same event we peeked above.
+ * same event we peeked above, unless it is copied to
+ * error_event.
*/
- fsnotify_remove_first_event(group);
+ if (fanotify_is_error_event(event->mask))
+ event = fanotify_dequeue_error_event(group, event, error_event);
+ else
+ fsnotify_remove_first_event(group);
+
if (fanotify_is_perm_event(event->mask))
FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED;
if (fanotify_is_hashed_event(event->mask))
@@ -309,6 +344,30 @@ static int process_access_response(struct fsnotify_group *group,
return -ENOENT;
}
+static size_t copy_error_info_to_user(struct fanotify_event *event,
+ char __user *buf, int count)
+{
+ struct fanotify_event_info_error info;
+ struct fanotify_error_event *fee = FANOTIFY_EE(event);
+
+ info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR;
+ info.hdr.pad = 0;
+ info.hdr.len = sizeof(struct fanotify_event_info_error);
+
+ if (WARN_ON(count < info.hdr.len))
+ return -EFAULT;
+
+ info.fsid = fee->fsid;
+ info.error = fee->error;
+ info.inode = fee->ino;
+ info.error_count = fee->err_count;
+
+ if (copy_to_user(buf, &info, sizeof(info)))
+ return -EFAULT;
+
+ return info.hdr.len;
+}
+
static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
int info_type, const char *name, size_t name_len,
char __user *buf, size_t count)
@@ -523,6 +582,14 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
count -= ret;
}
+ if (fanotify_is_error_event(event->mask)) {
+ ret = copy_error_info_to_user(event, buf, count);
+ if (ret < 0)
+ return ret;
+ buf += ret;
+ count -= ret;
+ }
+
return metadata.event_len;
out_close_fd:
@@ -553,6 +620,7 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
{
struct fsnotify_group *group;
struct fanotify_event *event;
+ struct fanotify_error_event error_event;
char __user *start;
int ret;
DEFINE_WAIT_FUNC(wait, woken_wake_function);
@@ -569,7 +637,7 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
* in case there are lots of available events.
*/
cond_resched();
- event = get_one_event(group, count);
+ event = get_one_event(group, count, &error_event);
if (IS_ERR(event)) {
ret = PTR_ERR(event);
break;
@@ -888,16 +956,33 @@ static int fanotify_remove_inode_mark(struct fsnotify_group *group,
flags, umask);
}
-static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
- __u32 mask,
- unsigned int flags)
+static int fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
+ __u32 mask, unsigned int flags,
+ __u32 *modified_mask)
{
+ struct fanotify_mark *mark = FANOTIFY_MARK(fsn_mark);
+ struct fanotify_error_event *error_event = NULL;
+ bool addition = !(flags & FAN_MARK_IGNORED_MASK);
__u32 oldmask = -1;
+ /* Only pre-alloc error_event if needed. */
+ if (addition && (mask & FAN_ERROR) && !mark->error_event) {
+ error_event = kzalloc(sizeof(*error_event), GFP_KERNEL);
+ if (!error_event)
+ return -ENOMEM;
+ fanotify_init_event(&error_event->fae, 0, FS_ERROR);
+ error_event->mark = mark;
+ }
+
spin_lock(&fsn_mark->lock);
- if (!(flags & FAN_MARK_IGNORED_MASK)) {
+ if (addition) {
oldmask = fsn_mark->mask;
fsn_mark->mask |= mask;
+
+ if (!mark->error_event) {
+ mark->error_event = error_event;
+ error_event = NULL;
+ }
} else {
fsn_mark->ignored_mask |= mask;
if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
@@ -905,7 +990,11 @@ static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
}
spin_unlock(&fsn_mark->lock);
- return mask & ~oldmask;
+ kfree(error_event);
+
+ *modified_mask = mask & ~oldmask;
+ return 0;
+
}
static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
@@ -955,6 +1044,7 @@ static int fanotify_add_mark(struct fsnotify_group *group,
{
struct fsnotify_mark *fsn_mark;
__u32 added;
+ int ret = 0;
mutex_lock(&group->mark_mutex);
fsn_mark = fsnotify_find_mark(connp, group);
@@ -965,13 +1055,18 @@ static int fanotify_add_mark(struct fsnotify_group *group,
return PTR_ERR(fsn_mark);
}
}
- added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
+ ret = fanotify_mark_add_to_mask(fsn_mark, mask, flags, &added);
+ if (ret)
+ goto out;
+
if (added & ~fsnotify_conn_mask(fsn_mark->connector))
fsnotify_recalc_mask(fsn_mark->connector);
+
+out:
mutex_unlock(&group->mark_mutex);
fsnotify_put_mark(fsn_mark);
- return 0;
+ return ret;
}
static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
@@ -1377,6 +1472,12 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
fsid = &__fsid;
}
+ if (mask & FAN_ERROR) {
+ ret = fanotify_test_fsid(path.dentry, &__fsid);
+ if (ret)
+ goto path_put_and_out;
+ fsid = &__fsid;
+ }
/* inode held in place by reference to path; group by fget on fd */
if (mark_type == FAN_MARK_INODE)
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index bad41bcb25df..05c929d588e4 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -81,9 +81,12 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
#define FANOTIFY_INODE_EVENTS (FANOTIFY_DIRENT_EVENTS | \
FAN_ATTRIB | FAN_MOVE_SELF | FAN_DELETE_SELF)
+#define FANOTIFY_ERROR_EVENTS (FAN_ERROR)
+
/* Events that user can request to be notified on */
#define FANOTIFY_EVENTS (FANOTIFY_PATH_EVENTS | \
- FANOTIFY_INODE_EVENTS)
+ FANOTIFY_INODE_EVENTS | \
+ FANOTIFY_ERROR_EVENTS)
/* Events that require a permission response from user */
#define FANOTIFY_PERM_EVENTS (FAN_OPEN_PERM | FAN_ACCESS_PERM | \
@@ -95,6 +98,7 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
/* Events that may be reported to user */
#define FANOTIFY_OUTGOING_EVENTS (FANOTIFY_EVENTS | \
FANOTIFY_PERM_EVENTS | \
+ FANOTIFY_ERROR_EVENTS | \
FAN_Q_OVERFLOW | FAN_ONDIR)
#define ALL_FANOTIFY_EVENT_BITS (FANOTIFY_OUTGOING_EVENTS | \
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index fbf9c5c7dd59..e3920597112f 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -20,6 +20,7 @@
#define FAN_OPEN_EXEC 0x00001000 /* File was opened for exec */
#define FAN_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
+#define FAN_ERROR 0x00008000 /* Filesystem error */
#define FAN_OPEN_PERM 0x00010000 /* File open in perm check */
#define FAN_ACCESS_PERM 0x00020000 /* File accessed in perm check */
@@ -123,6 +124,7 @@ struct fanotify_event_metadata {
#define FAN_EVENT_INFO_TYPE_FID 1
#define FAN_EVENT_INFO_TYPE_DFID_NAME 2
#define FAN_EVENT_INFO_TYPE_DFID 3
+#define FAN_EVENT_INFO_TYPE_ERROR 4
/* Variable length info record following event metadata */
struct fanotify_event_info_header {
@@ -148,6 +150,14 @@ struct fanotify_event_info_fid {
unsigned char handle[0];
};
+struct fanotify_event_info_error {
+ struct fanotify_event_info_header hdr;
+ int error;
+ __kernel_fsid_t fsid;
+ unsigned long inode;
+ __u32 error_count;
+};
+
struct fanotify_response {
__s32 fd;
__u32 response;
--
2.31.0
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