summaryrefslogtreecommitdiff
path: root/fs/notify/fanotify
diff options
context:
space:
mode:
Diffstat (limited to 'fs/notify/fanotify')
-rw-r--r--fs/notify/fanotify/Kconfig26
-rw-r--r--fs/notify/fanotify/Makefile1
-rw-r--r--fs/notify/fanotify/fanotify.c270
-rw-r--r--fs/notify/fanotify/fanotify.h50
-rw-r--r--fs/notify/fanotify/fanotify_user.c940
5 files changed, 1287 insertions, 0 deletions
diff --git a/fs/notify/fanotify/Kconfig b/fs/notify/fanotify/Kconfig
new file mode 100644
index 000000000..e5f911bd8
--- /dev/null
+++ b/fs/notify/fanotify/Kconfig
@@ -0,0 +1,26 @@
+config FANOTIFY
+ bool "Filesystem wide access notification"
+ select FSNOTIFY
+ select ANON_INODES
+ default n
+ ---help---
+ Say Y here to enable fanotify support. fanotify is a file access
+ notification system which differs from inotify in that it sends
+ an open file descriptor to the userspace listener along with
+ the event.
+
+ If unsure, say Y.
+
+config FANOTIFY_ACCESS_PERMISSIONS
+ bool "fanotify permissions checking"
+ depends on FANOTIFY
+ depends on SECURITY
+ default n
+ ---help---
+ Say Y here is you want fanotify listeners to be able to make permissions
+ decisions concerning filesystem events. This is used by some fanotify
+ listeners which need to scan files before allowing the system access to
+ use those files. This is used by some anti-malware vendors and by some
+ hierarchical storage managent systems.
+
+ If unsure, say N.
diff --git a/fs/notify/fanotify/Makefile b/fs/notify/fanotify/Makefile
new file mode 100644
index 000000000..0999213e7
--- /dev/null
+++ b/fs/notify/fanotify/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_FANOTIFY) += fanotify.o fanotify_user.o
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
new file mode 100644
index 000000000..d2f97ecca
--- /dev/null
+++ b/fs/notify/fanotify/fanotify.c
@@ -0,0 +1,270 @@
+#include <linux/fanotify.h>
+#include <linux/fdtable.h>
+#include <linux/fsnotify_backend.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h> /* UINT_MAX */
+#include <linux/mount.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#include "fanotify.h"
+
+static bool should_merge(struct fsnotify_event *old_fsn,
+ struct fsnotify_event *new_fsn)
+{
+ struct fanotify_event_info *old, *new;
+
+ pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn);
+ old = FANOTIFY_E(old_fsn);
+ new = FANOTIFY_E(new_fsn);
+
+ if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid &&
+ old->path.mnt == new->path.mnt &&
+ old->path.dentry == new->path.dentry)
+ return true;
+ return false;
+}
+
+/* and the list better be locked by something too! */
+static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
+{
+ struct fsnotify_event *test_event;
+ bool do_merge = false;
+
+ pr_debug("%s: list=%p event=%p\n", __func__, list, event);
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ /*
+ * Don't merge a permission event with any other event so that we know
+ * the event structure we have created in fanotify_handle_event() is the
+ * one we should check for permission response.
+ */
+ if (event->mask & FAN_ALL_PERM_EVENTS)
+ return 0;
+#endif
+
+ list_for_each_entry_reverse(test_event, list, list) {
+ if (should_merge(test_event, event)) {
+ do_merge = true;
+ break;
+ }
+ }
+
+ if (!do_merge)
+ return 0;
+
+ test_event->mask |= event->mask;
+ return 1;
+}
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+static int fanotify_get_response(struct fsnotify_group *group,
+ struct fanotify_perm_event_info *event)
+{
+ int ret;
+
+ pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+
+ wait_event(group->fanotify_data.access_waitq, event->response ||
+ atomic_read(&group->fanotify_data.bypass_perm));
+
+ if (!event->response) { /* bypass_perm set */
+ /*
+ * Event was canceled because group is being destroyed. Remove
+ * it from group's event list because we are responsible for
+ * freeing the permission event.
+ */
+ fsnotify_remove_event(group, &event->fae.fse);
+ return 0;
+ }
+
+ /* userspace responded, convert to something usable */
+ switch (event->response) {
+ case FAN_ALLOW:
+ ret = 0;
+ break;
+ case FAN_DENY:
+ default:
+ ret = -EPERM;
+ }
+ event->response = 0;
+
+ pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
+ group, event, ret);
+
+ return ret;
+}
+#endif
+
+static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
+ struct fsnotify_mark *vfsmnt_mark,
+ u32 event_mask,
+ void *data, int data_type)
+{
+ __u32 marks_mask, marks_ignored_mask;
+ struct path *path = data;
+
+ pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
+ " data_type=%d\n", __func__, inode_mark, vfsmnt_mark,
+ event_mask, data, data_type);
+
+ /* if we don't have enough info to send an event to userspace say no */
+ if (data_type != FSNOTIFY_EVENT_PATH)
+ return false;
+
+ /* sorry, fanotify only gives a damn about files and dirs */
+ if (!d_is_reg(path->dentry) &&
+ !d_can_lookup(path->dentry))
+ return false;
+
+ if (inode_mark && vfsmnt_mark) {
+ marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
+ marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
+ } else if (inode_mark) {
+ /*
+ * if the event is for a child and this inode doesn't care about
+ * events on the child, don't send it!
+ */
+ if ((event_mask & FS_EVENT_ON_CHILD) &&
+ !(inode_mark->mask & FS_EVENT_ON_CHILD))
+ return false;
+ marks_mask = inode_mark->mask;
+ marks_ignored_mask = inode_mark->ignored_mask;
+ } else if (vfsmnt_mark) {
+ marks_mask = vfsmnt_mark->mask;
+ marks_ignored_mask = vfsmnt_mark->ignored_mask;
+ } else {
+ BUG();
+ }
+
+ if (d_is_dir(path->dentry) &&
+ !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
+ return false;
+
+ if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask &
+ ~marks_ignored_mask)
+ return true;
+
+ return false;
+}
+
+struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
+ struct path *path)
+{
+ struct fanotify_event_info *event;
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ if (mask & FAN_ALL_PERM_EVENTS) {
+ struct fanotify_perm_event_info *pevent;
+
+ pevent = kmem_cache_alloc(fanotify_perm_event_cachep,
+ GFP_KERNEL);
+ if (!pevent)
+ return NULL;
+ event = &pevent->fae;
+ pevent->response = 0;
+ goto init;
+ }
+#endif
+ event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL);
+ if (!event)
+ return NULL;
+init: __maybe_unused
+ fsnotify_init_event(&event->fse, inode, mask);
+ event->tgid = get_pid(task_tgid(current));
+ if (path) {
+ event->path = *path;
+ path_get(&event->path);
+ } else {
+ event->path.mnt = NULL;
+ event->path.dentry = NULL;
+ }
+ return event;
+}
+
+static int fanotify_handle_event(struct fsnotify_group *group,
+ struct inode *inode,
+ struct fsnotify_mark *inode_mark,
+ struct fsnotify_mark *fanotify_mark,
+ u32 mask, void *data, int data_type,
+ const unsigned char *file_name, u32 cookie)
+{
+ int ret = 0;
+ struct fanotify_event_info *event;
+ struct fsnotify_event *fsn_event;
+
+ BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS);
+ BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY);
+ BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
+ BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE);
+ BUILD_BUG_ON(FAN_OPEN != FS_OPEN);
+ BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD);
+ BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW);
+ BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM);
+ BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
+ BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
+
+ if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data,
+ data_type))
+ return 0;
+
+ pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
+ mask);
+
+ event = fanotify_alloc_event(inode, mask, data);
+ if (unlikely(!event))
+ return -ENOMEM;
+
+ fsn_event = &event->fse;
+ ret = fsnotify_add_event(group, fsn_event, fanotify_merge);
+ if (ret) {
+ /* Permission events shouldn't be merged */
+ BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS);
+ /* Our event wasn't used in the end. Free it. */
+ fsnotify_destroy_event(group, fsn_event);
+
+ return 0;
+ }
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ if (mask & FAN_ALL_PERM_EVENTS) {
+ ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event));
+ fsnotify_destroy_event(group, fsn_event);
+ }
+#endif
+ return ret;
+}
+
+static void fanotify_free_group_priv(struct fsnotify_group *group)
+{
+ struct user_struct *user;
+
+ user = group->fanotify_data.user;
+ atomic_dec(&user->fanotify_listeners);
+ free_uid(user);
+}
+
+static void fanotify_free_event(struct fsnotify_event *fsn_event)
+{
+ struct fanotify_event_info *event;
+
+ event = FANOTIFY_E(fsn_event);
+ path_put(&event->path);
+ put_pid(event->tgid);
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ if (fsn_event->mask & FAN_ALL_PERM_EVENTS) {
+ kmem_cache_free(fanotify_perm_event_cachep,
+ FANOTIFY_PE(fsn_event));
+ return;
+ }
+#endif
+ kmem_cache_free(fanotify_event_cachep, event);
+}
+
+const struct fsnotify_ops fanotify_fsnotify_ops = {
+ .handle_event = fanotify_handle_event,
+ .free_group_priv = fanotify_free_group_priv,
+ .free_event = fanotify_free_event,
+};
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
new file mode 100644
index 000000000..2a5fb1411
--- /dev/null
+++ b/fs/notify/fanotify/fanotify.h
@@ -0,0 +1,50 @@
+#include <linux/fsnotify_backend.h>
+#include <linux/path.h>
+#include <linux/slab.h>
+
+extern struct kmem_cache *fanotify_event_cachep;
+extern struct kmem_cache *fanotify_perm_event_cachep;
+
+/*
+ * Structure for normal fanotify events. It gets allocated in
+ * fanotify_handle_event() and freed when the information is retrieved by
+ * userspace
+ */
+struct fanotify_event_info {
+ struct fsnotify_event fse;
+ /*
+ * We hold ref to this path so it may be dereferenced at any point
+ * during this object's lifetime
+ */
+ struct path path;
+ struct pid *tgid;
+};
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+/*
+ * Structure for permission fanotify events. It gets allocated and freed in
+ * fanotify_handle_event() since we wait there for user response. When the
+ * information is retrieved by userspace the structure is moved from
+ * group->notification_list to group->fanotify_data.access_list to wait for
+ * user response.
+ */
+struct fanotify_perm_event_info {
+ struct fanotify_event_info fae;
+ int response; /* userspace answer to question */
+ int fd; /* fd we passed to userspace for this event */
+};
+
+static inline struct fanotify_perm_event_info *
+FANOTIFY_PE(struct fsnotify_event *fse)
+{
+ return container_of(fse, struct fanotify_perm_event_info, fae.fse);
+}
+#endif
+
+static inline struct fanotify_event_info *FANOTIFY_E(struct fsnotify_event *fse)
+{
+ return container_of(fse, struct fanotify_event_info, fse);
+}
+
+struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
+ struct path *path);
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
new file mode 100644
index 000000000..cf275500a
--- /dev/null
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -0,0 +1,940 @@
+#include <linux/fanotify.h>
+#include <linux/fcntl.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/anon_inodes.h>
+#include <linux/fsnotify_backend.h>
+#include <linux/init.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/poll.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/compat.h>
+
+#include <asm/ioctls.h>
+
+#include "../../mount.h"
+#include "../fdinfo.h"
+#include "fanotify.h"
+
+#define FANOTIFY_DEFAULT_MAX_EVENTS 16384
+#define FANOTIFY_DEFAULT_MAX_MARKS 8192
+#define FANOTIFY_DEFAULT_MAX_LISTENERS 128
+
+/*
+ * All flags that may be specified in parameter event_f_flags of fanotify_init.
+ *
+ * Internal and external open flags are stored together in field f_flags of
+ * struct file. Only external open flags shall be allowed in event_f_flags.
+ * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be
+ * excluded.
+ */
+#define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \
+ O_ACCMODE | O_APPEND | O_NONBLOCK | \
+ __O_SYNC | O_DSYNC | O_CLOEXEC | \
+ O_LARGEFILE | O_NOATIME )
+
+extern const struct fsnotify_ops fanotify_fsnotify_ops;
+
+static struct kmem_cache *fanotify_mark_cache __read_mostly;
+struct kmem_cache *fanotify_event_cachep __read_mostly;
+struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
+
+/*
+ * Get an fsnotify notification event if one exists and is small
+ * enough to fit in "count". Return an error pointer if the count
+ * is not large enough.
+ *
+ * Called with the group->notification_mutex held.
+ */
+static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
+ size_t count)
+{
+ BUG_ON(!mutex_is_locked(&group->notification_mutex));
+
+ pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
+
+ if (fsnotify_notify_queue_is_empty(group))
+ return NULL;
+
+ if (FAN_EVENT_METADATA_LEN > count)
+ return ERR_PTR(-EINVAL);
+
+ /* held the notification_mutex the whole time, so this is the
+ * same event we peeked above */
+ return fsnotify_remove_first_event(group);
+}
+
+static int create_fd(struct fsnotify_group *group,
+ struct fanotify_event_info *event,
+ struct file **file)
+{
+ int client_fd;
+ struct file *new_file;
+
+ pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+
+ client_fd = get_unused_fd_flags(group->fanotify_data.f_flags);
+ if (client_fd < 0)
+ return client_fd;
+
+ /*
+ * we need a new file handle for the userspace program so it can read even if it was
+ * originally opened O_WRONLY.
+ */
+ /* it's possible this event was an overflow event. in that case dentry and mnt
+ * are NULL; That's fine, just don't call dentry open */
+ if (event->path.dentry && event->path.mnt)
+ new_file = dentry_open(&event->path,
+ group->fanotify_data.f_flags | FMODE_NONOTIFY,
+ current_cred());
+ else
+ new_file = ERR_PTR(-EOVERFLOW);
+ if (IS_ERR(new_file)) {
+ /*
+ * we still send an event even if we can't open the file. this
+ * can happen when say tasks are gone and we try to open their
+ * /proc files or we try to open a WRONLY file like in sysfs
+ * we just send the errno to userspace since there isn't much
+ * else we can do.
+ */
+ put_unused_fd(client_fd);
+ client_fd = PTR_ERR(new_file);
+ } else {
+ *file = new_file;
+ }
+
+ return client_fd;
+}
+
+static int fill_event_metadata(struct fsnotify_group *group,
+ struct fanotify_event_metadata *metadata,
+ struct fsnotify_event *fsn_event,
+ struct file **file)
+{
+ int ret = 0;
+ struct fanotify_event_info *event;
+
+ pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
+ group, metadata, fsn_event);
+
+ *file = NULL;
+ event = container_of(fsn_event, struct fanotify_event_info, fse);
+ metadata->event_len = FAN_EVENT_METADATA_LEN;
+ metadata->metadata_len = FAN_EVENT_METADATA_LEN;
+ metadata->vers = FANOTIFY_METADATA_VERSION;
+ metadata->reserved = 0;
+ metadata->mask = fsn_event->mask & FAN_ALL_OUTGOING_EVENTS;
+ metadata->pid = pid_vnr(event->tgid);
+ if (unlikely(fsn_event->mask & FAN_Q_OVERFLOW))
+ metadata->fd = FAN_NOFD;
+ else {
+ metadata->fd = create_fd(group, event, file);
+ if (metadata->fd < 0)
+ ret = metadata->fd;
+ }
+
+ return ret;
+}
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+static struct fanotify_perm_event_info *dequeue_event(
+ struct fsnotify_group *group, int fd)
+{
+ struct fanotify_perm_event_info *event, *return_e = NULL;
+
+ spin_lock(&group->fanotify_data.access_lock);
+ list_for_each_entry(event, &group->fanotify_data.access_list,
+ fae.fse.list) {
+ if (event->fd != fd)
+ continue;
+
+ list_del_init(&event->fae.fse.list);
+ return_e = event;
+ break;
+ }
+ spin_unlock(&group->fanotify_data.access_lock);
+
+ pr_debug("%s: found return_re=%p\n", __func__, return_e);
+
+ return return_e;
+}
+
+static int process_access_response(struct fsnotify_group *group,
+ struct fanotify_response *response_struct)
+{
+ struct fanotify_perm_event_info *event;
+ int fd = response_struct->fd;
+ int response = response_struct->response;
+
+ pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
+ fd, response);
+ /*
+ * make sure the response is valid, if invalid we do nothing and either
+ * userspace can send a valid response or we will clean it up after the
+ * timeout
+ */
+ switch (response) {
+ case FAN_ALLOW:
+ case FAN_DENY:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (fd < 0)
+ return -EINVAL;
+
+ event = dequeue_event(group, fd);
+ if (!event)
+ return -ENOENT;
+
+ event->response = response;
+ wake_up(&group->fanotify_data.access_waitq);
+
+ return 0;
+}
+#endif
+
+static ssize_t copy_event_to_user(struct fsnotify_group *group,
+ struct fsnotify_event *event,
+ char __user *buf)
+{
+ struct fanotify_event_metadata fanotify_event_metadata;
+ struct file *f;
+ int fd, ret;
+
+ pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+
+ ret = fill_event_metadata(group, &fanotify_event_metadata, event, &f);
+ if (ret < 0)
+ return ret;
+
+ fd = fanotify_event_metadata.fd;
+ ret = -EFAULT;
+ if (copy_to_user(buf, &fanotify_event_metadata,
+ fanotify_event_metadata.event_len))
+ goto out_close_fd;
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ if (event->mask & FAN_ALL_PERM_EVENTS)
+ FANOTIFY_PE(event)->fd = fd;
+#endif
+
+ if (fd != FAN_NOFD)
+ fd_install(fd, f);
+ return fanotify_event_metadata.event_len;
+
+out_close_fd:
+ if (fd != FAN_NOFD) {
+ put_unused_fd(fd);
+ fput(f);
+ }
+ return ret;
+}
+
+/* intofiy userspace file descriptor functions */
+static unsigned int fanotify_poll(struct file *file, poll_table *wait)
+{
+ struct fsnotify_group *group = file->private_data;
+ int ret = 0;
+
+ poll_wait(file, &group->notification_waitq, wait);
+ mutex_lock(&group->notification_mutex);
+ if (!fsnotify_notify_queue_is_empty(group))
+ ret = POLLIN | POLLRDNORM;
+ mutex_unlock(&group->notification_mutex);
+
+ return ret;
+}
+
+static ssize_t fanotify_read(struct file *file, char __user *buf,
+ size_t count, loff_t *pos)
+{
+ struct fsnotify_group *group;
+ struct fsnotify_event *kevent;
+ char __user *start;
+ int ret;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
+
+ start = buf;
+ group = file->private_data;
+
+ pr_debug("%s: group=%p\n", __func__, group);
+
+ add_wait_queue(&group->notification_waitq, &wait);
+ while (1) {
+ mutex_lock(&group->notification_mutex);
+ kevent = get_one_event(group, count);
+ mutex_unlock(&group->notification_mutex);
+
+ if (IS_ERR(kevent)) {
+ ret = PTR_ERR(kevent);
+ break;
+ }
+
+ if (!kevent) {
+ ret = -EAGAIN;
+ if (file->f_flags & O_NONBLOCK)
+ break;
+
+ ret = -ERESTARTSYS;
+ if (signal_pending(current))
+ break;
+
+ if (start != buf)
+ break;
+
+ wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+ continue;
+ }
+
+ ret = copy_event_to_user(group, kevent, buf);
+ /*
+ * Permission events get queued to wait for response. Other
+ * events can be destroyed now.
+ */
+ if (!(kevent->mask & FAN_ALL_PERM_EVENTS)) {
+ fsnotify_destroy_event(group, kevent);
+ if (ret < 0)
+ break;
+ } else {
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ if (ret < 0) {
+ FANOTIFY_PE(kevent)->response = FAN_DENY;
+ wake_up(&group->fanotify_data.access_waitq);
+ break;
+ }
+ spin_lock(&group->fanotify_data.access_lock);
+ list_add_tail(&kevent->list,
+ &group->fanotify_data.access_list);
+ spin_unlock(&group->fanotify_data.access_lock);
+#endif
+ }
+ buf += ret;
+ count -= ret;
+ }
+ remove_wait_queue(&group->notification_waitq, &wait);
+
+ if (start != buf && ret != -EFAULT)
+ ret = buf - start;
+ return ret;
+}
+
+static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
+{
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ struct fanotify_response response = { .fd = -1, .response = -1 };
+ struct fsnotify_group *group;
+ int ret;
+
+ group = file->private_data;
+
+ if (count > sizeof(response))
+ count = sizeof(response);
+
+ pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
+
+ if (copy_from_user(&response, buf, count))
+ return -EFAULT;
+
+ ret = process_access_response(group, &response);
+ if (ret < 0)
+ count = ret;
+
+ return count;
+#else
+ return -EINVAL;
+#endif
+}
+
+static int fanotify_release(struct inode *ignored, struct file *file)
+{
+ struct fsnotify_group *group = file->private_data;
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ struct fanotify_perm_event_info *event, *next;
+
+ /*
+ * There may be still new events arriving in the notification queue
+ * but since userspace cannot use fanotify fd anymore, no event can
+ * enter or leave access_list by now.
+ */
+ spin_lock(&group->fanotify_data.access_lock);
+
+ atomic_inc(&group->fanotify_data.bypass_perm);
+
+ list_for_each_entry_safe(event, next, &group->fanotify_data.access_list,
+ fae.fse.list) {
+ pr_debug("%s: found group=%p event=%p\n", __func__, group,
+ event);
+
+ list_del_init(&event->fae.fse.list);
+ event->response = FAN_ALLOW;
+ }
+ spin_unlock(&group->fanotify_data.access_lock);
+
+ /*
+ * Since bypass_perm is set, newly queued events will not wait for
+ * access response. Wake up the already sleeping ones now.
+ * synchronize_srcu() in fsnotify_destroy_group() will wait for all
+ * processes sleeping in fanotify_handle_event() waiting for access
+ * response and thus also for all permission events to be freed.
+ */
+ wake_up(&group->fanotify_data.access_waitq);
+#endif
+
+ /* matches the fanotify_init->fsnotify_alloc_group */
+ fsnotify_destroy_group(group);
+
+ return 0;
+}
+
+static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct fsnotify_group *group;
+ struct fsnotify_event *fsn_event;
+ void __user *p;
+ int ret = -ENOTTY;
+ size_t send_len = 0;
+
+ group = file->private_data;
+
+ p = (void __user *) arg;
+
+ switch (cmd) {
+ case FIONREAD:
+ mutex_lock(&group->notification_mutex);
+ list_for_each_entry(fsn_event, &group->notification_list, list)
+ send_len += FAN_EVENT_METADATA_LEN;
+ mutex_unlock(&group->notification_mutex);
+ ret = put_user(send_len, (int __user *) p);
+ break;
+ }
+
+ return ret;
+}
+
+static const struct file_operations fanotify_fops = {
+ .show_fdinfo = fanotify_show_fdinfo,
+ .poll = fanotify_poll,
+ .read = fanotify_read,
+ .write = fanotify_write,
+ .fasync = NULL,
+ .release = fanotify_release,
+ .unlocked_ioctl = fanotify_ioctl,
+ .compat_ioctl = fanotify_ioctl,
+ .llseek = noop_llseek,
+};
+
+static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
+{
+ kmem_cache_free(fanotify_mark_cache, fsn_mark);
+}
+
+static int fanotify_find_path(int dfd, const char __user *filename,
+ struct path *path, unsigned int flags)
+{
+ int ret;
+
+ pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
+ dfd, filename, flags);
+
+ if (filename == NULL) {
+ struct fd f = fdget(dfd);
+
+ ret = -EBADF;
+ if (!f.file)
+ goto out;
+
+ ret = -ENOTDIR;
+ if ((flags & FAN_MARK_ONLYDIR) &&
+ !(S_ISDIR(file_inode(f.file)->i_mode))) {
+ fdput(f);
+ goto out;
+ }
+
+ *path = f.file->f_path;
+ path_get(path);
+ fdput(f);
+ } else {
+ unsigned int lookup_flags = 0;
+
+ if (!(flags & FAN_MARK_DONT_FOLLOW))
+ lookup_flags |= LOOKUP_FOLLOW;
+ if (flags & FAN_MARK_ONLYDIR)
+ lookup_flags |= LOOKUP_DIRECTORY;
+
+ ret = user_path_at(dfd, filename, lookup_flags, path);
+ if (ret)
+ goto out;
+ }
+
+ /* you can only watch an inode if you have read permissions on it */
+ ret = inode_permission(path->dentry->d_inode, MAY_READ);
+ if (ret)
+ path_put(path);
+out:
+ return ret;
+}
+
+static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
+ __u32 mask,
+ unsigned int flags,
+ int *destroy)
+{
+ __u32 oldmask = 0;
+
+ spin_lock(&fsn_mark->lock);
+ if (!(flags & FAN_MARK_IGNORED_MASK)) {
+ __u32 tmask = fsn_mark->mask & ~mask;
+
+ if (flags & FAN_MARK_ONDIR)
+ tmask &= ~FAN_ONDIR;
+
+ oldmask = fsn_mark->mask;
+ fsnotify_set_mark_mask_locked(fsn_mark, tmask);
+ } else {
+ __u32 tmask = fsn_mark->ignored_mask & ~mask;
+ if (flags & FAN_MARK_ONDIR)
+ tmask &= ~FAN_ONDIR;
+
+ fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
+ }
+ *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask);
+ spin_unlock(&fsn_mark->lock);
+
+ return mask & oldmask;
+}
+
+static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
+ struct vfsmount *mnt, __u32 mask,
+ unsigned int flags)
+{
+ struct fsnotify_mark *fsn_mark = NULL;
+ __u32 removed;
+ int destroy_mark;
+
+ mutex_lock(&group->mark_mutex);
+ fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
+ if (!fsn_mark) {
+ mutex_unlock(&group->mark_mutex);
+ return -ENOENT;
+ }
+
+ removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
+ &destroy_mark);
+ if (destroy_mark)
+ fsnotify_destroy_mark_locked(fsn_mark, group);
+ mutex_unlock(&group->mark_mutex);
+
+ fsnotify_put_mark(fsn_mark);
+ if (removed & real_mount(mnt)->mnt_fsnotify_mask)
+ fsnotify_recalc_vfsmount_mask(mnt);
+
+ return 0;
+}
+
+static int fanotify_remove_inode_mark(struct fsnotify_group *group,
+ struct inode *inode, __u32 mask,
+ unsigned int flags)
+{
+ struct fsnotify_mark *fsn_mark = NULL;
+ __u32 removed;
+ int destroy_mark;
+
+ mutex_lock(&group->mark_mutex);
+ fsn_mark = fsnotify_find_inode_mark(group, inode);
+ if (!fsn_mark) {
+ mutex_unlock(&group->mark_mutex);
+ return -ENOENT;
+ }
+
+ removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
+ &destroy_mark);
+ if (destroy_mark)
+ fsnotify_destroy_mark_locked(fsn_mark, group);
+ mutex_unlock(&group->mark_mutex);
+
+ /* matches the fsnotify_find_inode_mark() */
+ fsnotify_put_mark(fsn_mark);
+ if (removed & inode->i_fsnotify_mask)
+ fsnotify_recalc_inode_mask(inode);
+
+ return 0;
+}
+
+static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
+ __u32 mask,
+ unsigned int flags)
+{
+ __u32 oldmask = -1;
+
+ spin_lock(&fsn_mark->lock);
+ if (!(flags & FAN_MARK_IGNORED_MASK)) {
+ __u32 tmask = fsn_mark->mask | mask;
+
+ if (flags & FAN_MARK_ONDIR)
+ tmask |= FAN_ONDIR;
+
+ oldmask = fsn_mark->mask;
+ fsnotify_set_mark_mask_locked(fsn_mark, tmask);
+ } else {
+ __u32 tmask = fsn_mark->ignored_mask | mask;
+ if (flags & FAN_MARK_ONDIR)
+ tmask |= FAN_ONDIR;
+
+ fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
+ if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
+ fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
+ }
+ spin_unlock(&fsn_mark->lock);
+
+ return mask & ~oldmask;
+}
+
+static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
+ struct inode *inode,
+ struct vfsmount *mnt)
+{
+ struct fsnotify_mark *mark;
+ int ret;
+
+ if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
+ return ERR_PTR(-ENOSPC);
+
+ mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
+ if (!mark)
+ return ERR_PTR(-ENOMEM);
+
+ fsnotify_init_mark(mark, fanotify_free_mark);
+ ret = fsnotify_add_mark_locked(mark, group, inode, mnt, 0);
+ if (ret) {
+ fsnotify_put_mark(mark);
+ return ERR_PTR(ret);
+ }
+
+ return mark;
+}
+
+
+static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
+ struct vfsmount *mnt, __u32 mask,
+ unsigned int flags)
+{
+ struct fsnotify_mark *fsn_mark;
+ __u32 added;
+
+ mutex_lock(&group->mark_mutex);
+ fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
+ if (!fsn_mark) {
+ fsn_mark = fanotify_add_new_mark(group, NULL, mnt);
+ if (IS_ERR(fsn_mark)) {
+ mutex_unlock(&group->mark_mutex);
+ return PTR_ERR(fsn_mark);
+ }
+ }
+ added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
+ mutex_unlock(&group->mark_mutex);
+
+ if (added & ~real_mount(mnt)->mnt_fsnotify_mask)
+ fsnotify_recalc_vfsmount_mask(mnt);
+
+ fsnotify_put_mark(fsn_mark);
+ return 0;
+}
+
+static int fanotify_add_inode_mark(struct fsnotify_group *group,
+ struct inode *inode, __u32 mask,
+ unsigned int flags)
+{
+ struct fsnotify_mark *fsn_mark;
+ __u32 added;
+
+ pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
+
+ /*
+ * If some other task has this inode open for write we should not add
+ * an ignored mark, unless that ignored mark is supposed to survive
+ * modification changes anyway.
+ */
+ if ((flags & FAN_MARK_IGNORED_MASK) &&
+ !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
+ (atomic_read(&inode->i_writecount) > 0))
+ return 0;
+
+ mutex_lock(&group->mark_mutex);
+ fsn_mark = fsnotify_find_inode_mark(group, inode);
+ if (!fsn_mark) {
+ fsn_mark = fanotify_add_new_mark(group, inode, NULL);
+ if (IS_ERR(fsn_mark)) {
+ mutex_unlock(&group->mark_mutex);
+ return PTR_ERR(fsn_mark);
+ }
+ }
+ added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
+ mutex_unlock(&group->mark_mutex);
+
+ if (added & ~inode->i_fsnotify_mask)
+ fsnotify_recalc_inode_mask(inode);
+
+ fsnotify_put_mark(fsn_mark);
+ return 0;
+}
+
+/* fanotify syscalls */
+SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
+{
+ struct fsnotify_group *group;
+ int f_flags, fd;
+ struct user_struct *user;
+ struct fanotify_event_info *oevent;
+
+ pr_debug("%s: flags=%d event_f_flags=%d\n",
+ __func__, flags, event_f_flags);
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (flags & ~FAN_ALL_INIT_FLAGS)
+ return -EINVAL;
+
+ if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS)
+ return -EINVAL;
+
+ switch (event_f_flags & O_ACCMODE) {
+ case O_RDONLY:
+ case O_RDWR:
+ case O_WRONLY:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ user = get_current_user();
+ if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
+ free_uid(user);
+ return -EMFILE;
+ }
+
+ f_flags = O_RDWR | FMODE_NONOTIFY;
+ if (flags & FAN_CLOEXEC)
+ f_flags |= O_CLOEXEC;
+ if (flags & FAN_NONBLOCK)
+ f_flags |= O_NONBLOCK;
+
+ /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */
+ group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
+ if (IS_ERR(group)) {
+ free_uid(user);
+ return PTR_ERR(group);
+ }
+
+ group->fanotify_data.user = user;
+ atomic_inc(&user->fanotify_listeners);
+
+ oevent = fanotify_alloc_event(NULL, FS_Q_OVERFLOW, NULL);
+ if (unlikely(!oevent)) {
+ fd = -ENOMEM;
+ goto out_destroy_group;
+ }
+ group->overflow_event = &oevent->fse;
+
+ if (force_o_largefile())
+ event_f_flags |= O_LARGEFILE;
+ group->fanotify_data.f_flags = event_f_flags;
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ spin_lock_init(&group->fanotify_data.access_lock);
+ init_waitqueue_head(&group->fanotify_data.access_waitq);
+ INIT_LIST_HEAD(&group->fanotify_data.access_list);
+ atomic_set(&group->fanotify_data.bypass_perm, 0);
+#endif
+ switch (flags & FAN_ALL_CLASS_BITS) {
+ case FAN_CLASS_NOTIF:
+ group->priority = FS_PRIO_0;
+ break;
+ case FAN_CLASS_CONTENT:
+ group->priority = FS_PRIO_1;
+ break;
+ case FAN_CLASS_PRE_CONTENT:
+ group->priority = FS_PRIO_2;
+ break;
+ default:
+ fd = -EINVAL;
+ goto out_destroy_group;
+ }
+
+ if (flags & FAN_UNLIMITED_QUEUE) {
+ fd = -EPERM;
+ if (!capable(CAP_SYS_ADMIN))
+ goto out_destroy_group;
+ group->max_events = UINT_MAX;
+ } else {
+ group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
+ }
+
+ if (flags & FAN_UNLIMITED_MARKS) {
+ fd = -EPERM;
+ if (!capable(CAP_SYS_ADMIN))
+ goto out_destroy_group;
+ group->fanotify_data.max_marks = UINT_MAX;
+ } else {
+ group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
+ }
+
+ fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
+ if (fd < 0)
+ goto out_destroy_group;
+
+ return fd;
+
+out_destroy_group:
+ fsnotify_destroy_group(group);
+ return fd;
+}
+
+SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
+ __u64, mask, int, dfd,
+ const char __user *, pathname)
+{
+ struct inode *inode = NULL;
+ struct vfsmount *mnt = NULL;
+ struct fsnotify_group *group;
+ struct fd f;
+ struct path path;
+ int ret;
+
+ pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
+ __func__, fanotify_fd, flags, dfd, pathname, mask);
+
+ /* we only use the lower 32 bits as of right now. */
+ if (mask & ((__u64)0xffffffff << 32))
+ return -EINVAL;
+
+ if (flags & ~FAN_ALL_MARK_FLAGS)
+ return -EINVAL;
+ switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
+ case FAN_MARK_ADD: /* fallthrough */
+ case FAN_MARK_REMOVE:
+ if (!mask)
+ return -EINVAL;
+ break;
+ case FAN_MARK_FLUSH:
+ if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH))
+ return -EINVAL;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (mask & FAN_ONDIR) {
+ flags |= FAN_MARK_ONDIR;
+ mask &= ~FAN_ONDIR;
+ }
+
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
+#else
+ if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
+#endif
+ return -EINVAL;
+
+ f = fdget(fanotify_fd);
+ if (unlikely(!f.file))
+ return -EBADF;
+
+ /* verify that this is indeed an fanotify instance */
+ ret = -EINVAL;
+ if (unlikely(f.file->f_op != &fanotify_fops))
+ goto fput_and_out;
+ group = f.file->private_data;
+
+ /*
+ * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not
+ * allowed to set permissions events.
+ */
+ ret = -EINVAL;
+ if (mask & FAN_ALL_PERM_EVENTS &&
+ group->priority == FS_PRIO_0)
+ goto fput_and_out;
+
+ if (flags & FAN_MARK_FLUSH) {
+ ret = 0;
+ if (flags & FAN_MARK_MOUNT)
+ fsnotify_clear_vfsmount_marks_by_group(group);
+ else
+ fsnotify_clear_inode_marks_by_group(group);
+ goto fput_and_out;
+ }
+
+ ret = fanotify_find_path(dfd, pathname, &path, flags);
+ if (ret)
+ goto fput_and_out;
+
+ /* inode held in place by reference to path; group by fget on fd */
+ if (!(flags & FAN_MARK_MOUNT))
+ inode = path.dentry->d_inode;
+ else
+ mnt = path.mnt;
+
+ /* create/update an inode mark */
+ switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
+ case FAN_MARK_ADD:
+ if (flags & FAN_MARK_MOUNT)
+ ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
+ else
+ ret = fanotify_add_inode_mark(group, inode, mask, flags);
+ break;
+ case FAN_MARK_REMOVE:
+ if (flags & FAN_MARK_MOUNT)
+ ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
+ else
+ ret = fanotify_remove_inode_mark(group, inode, mask, flags);
+ break;
+ default:
+ ret = -EINVAL;
+ }
+
+ path_put(&path);
+fput_and_out:
+ fdput(f);
+ return ret;
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE6(fanotify_mark,
+ int, fanotify_fd, unsigned int, flags,
+ __u32, mask0, __u32, mask1, int, dfd,
+ const char __user *, pathname)
+{
+ return sys_fanotify_mark(fanotify_fd, flags,
+#ifdef __BIG_ENDIAN
+ ((__u64)mask0 << 32) | mask1,
+#else
+ ((__u64)mask1 << 32) | mask0,
+#endif
+ dfd, pathname);
+}
+#endif
+
+/*
+ * fanotify_user_setup - Our initialization function. Note that we cannot return
+ * error because we have compiled-in VFS hooks. So an (unlikely) failure here
+ * must result in panic().
+ */
+static int __init fanotify_user_setup(void)
+{
+ fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
+ fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC);
+#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+ fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event_info,
+ SLAB_PANIC);
+#endif
+
+ return 0;
+}
+device_initcall(fanotify_user_setup);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-07-04 21:34:14 +0000