Resguardo inicial

linux-7.2.3/fs/notify/fanotify/Kconfig

@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config FANOTIFY
+	bool "Filesystem wide access notification"
+	select FSNOTIFY
+	select EXPORTFS
+	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
+	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 management systems.
+
+	   If unsure, say N.

linux-7.2.3/fs/notify/fanotify/Makefile

@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_FANOTIFY)		+= fanotify.o fanotify_user.o

linux-7.2.3/fs/notify/fanotify/fanotify.h

@@ -0,0 +1,555 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/fsnotify_backend.h>
+#include <linux/path.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/exportfs.h>
+#include <linux/hashtable.h>
+
+extern struct kmem_cache *fanotify_mark_cache;
+extern struct kmem_cache *fanotify_fid_event_cachep;
+extern struct kmem_cache *fanotify_path_event_cachep;
+extern struct kmem_cache *fanotify_perm_event_cachep;
+extern struct kmem_cache *fanotify_mnt_event_cachep;
+
+/* Possible states of the permission event */
+enum {
+	FAN_EVENT_INIT,
+	FAN_EVENT_REPORTED,
+	FAN_EVENT_ANSWERED,
+	FAN_EVENT_CANCELED,
+};
+
+/*
+ * 3 dwords are sufficient for most local fs (64bit ino, 32bit generation).
+ * fh buf should be dword aligned. On 64bit arch, the ext_buf pointer is
+ * stored in either the first or last 2 dwords.
+ */
+#define FANOTIFY_INLINE_FH_LEN	(3 << 2)
+#define FANOTIFY_FH_HDR_LEN	sizeof(struct fanotify_fh)
+
+/* Fixed size struct for file handle */
+struct fanotify_fh {
+	u8 type;
+	u8 len;
+#define FANOTIFY_FH_FLAG_EXT_BUF 1
+	u8 flags;
+	u8 pad;
+} __aligned(4);
+
+/* Variable size struct for dir file handle + child file handle + name */
+struct fanotify_info {
+	/* size of dir_fh/file_fh including fanotify_fh hdr size */
+	u8 dir_fh_totlen;
+	u8 dir2_fh_totlen;
+	u8 file_fh_totlen;
+	u8 name_len;
+	u8 name2_len;
+	u8 pad[3];
+	unsigned char buf[];
+	/*
+	 * (struct fanotify_fh) dir_fh starts at buf[0]
+	 * (optional) dir2_fh starts at buf[dir_fh_totlen]
+	 * (optional) file_fh starts at buf[dir_fh_totlen + dir2_fh_totlen]
+	 * name starts at buf[dir_fh_totlen + dir2_fh_totlen + file_fh_totlen]
+	 * ...
+	 */
+#define FANOTIFY_DIR_FH_SIZE(info)	((info)->dir_fh_totlen)
+#define FANOTIFY_DIR2_FH_SIZE(info)	((info)->dir2_fh_totlen)
+#define FANOTIFY_FILE_FH_SIZE(info)	((info)->file_fh_totlen)
+#define FANOTIFY_NAME_SIZE(info)	((info)->name_len + 1)
+#define FANOTIFY_NAME2_SIZE(info)	((info)->name2_len + 1)
+
+#define FANOTIFY_DIR_FH_OFFSET(info)	0
+#define FANOTIFY_DIR2_FH_OFFSET(info) \
+	(FANOTIFY_DIR_FH_OFFSET(info) + FANOTIFY_DIR_FH_SIZE(info))
+#define FANOTIFY_FILE_FH_OFFSET(info) \
+	(FANOTIFY_DIR2_FH_OFFSET(info) + FANOTIFY_DIR2_FH_SIZE(info))
+#define FANOTIFY_NAME_OFFSET(info) \
+	(FANOTIFY_FILE_FH_OFFSET(info) + FANOTIFY_FILE_FH_SIZE(info))
+#define FANOTIFY_NAME2_OFFSET(info) \
+	(FANOTIFY_NAME_OFFSET(info) + FANOTIFY_NAME_SIZE(info))
+
+#define FANOTIFY_DIR_FH_BUF(info) \
+	((info)->buf + FANOTIFY_DIR_FH_OFFSET(info))
+#define FANOTIFY_DIR2_FH_BUF(info) \
+	((info)->buf + FANOTIFY_DIR2_FH_OFFSET(info))
+#define FANOTIFY_FILE_FH_BUF(info) \
+	((info)->buf + FANOTIFY_FILE_FH_OFFSET(info))
+#define FANOTIFY_NAME_BUF(info) \
+	((info)->buf + FANOTIFY_NAME_OFFSET(info))
+#define FANOTIFY_NAME2_BUF(info) \
+	((info)->buf + FANOTIFY_NAME2_OFFSET(info))
+} __aligned(4);
+
+static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh)
+{
+	return (fh->flags & FANOTIFY_FH_FLAG_EXT_BUF);
+}
+
+static inline char **fanotify_fh_ext_buf_ptr(struct fanotify_fh *fh)
+{
+	BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN % 4);
+	BUILD_BUG_ON(__alignof__(char *) - 4 + sizeof(char *) >
+		     FANOTIFY_INLINE_FH_LEN);
+	return (char **)ALIGN((unsigned long)(fh + 1), __alignof__(char *));
+}
+
+static inline void *fanotify_fh_ext_buf(struct fanotify_fh *fh)
+{
+	return *fanotify_fh_ext_buf_ptr(fh);
+}
+
+static inline void *fanotify_fh_buf(struct fanotify_fh *fh)
+{
+	return fanotify_fh_has_ext_buf(fh) ? fanotify_fh_ext_buf(fh) : fh + 1;
+}
+
+static inline int fanotify_info_dir_fh_len(struct fanotify_info *info)
+{
+	if (!info->dir_fh_totlen ||
+	    WARN_ON_ONCE(info->dir_fh_totlen < FANOTIFY_FH_HDR_LEN))
+		return 0;
+
+	return info->dir_fh_totlen - FANOTIFY_FH_HDR_LEN;
+}
+
+static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *info)
+{
+	BUILD_BUG_ON(offsetof(struct fanotify_info, buf) % 4);
+
+	return (struct fanotify_fh *)FANOTIFY_DIR_FH_BUF(info);
+}
+
+static inline int fanotify_info_dir2_fh_len(struct fanotify_info *info)
+{
+	if (!info->dir2_fh_totlen ||
+	    WARN_ON_ONCE(info->dir2_fh_totlen < FANOTIFY_FH_HDR_LEN))
+		return 0;
+
+	return info->dir2_fh_totlen - FANOTIFY_FH_HDR_LEN;
+}
+
+static inline struct fanotify_fh *fanotify_info_dir2_fh(struct fanotify_info *info)
+{
+	return (struct fanotify_fh *)FANOTIFY_DIR2_FH_BUF(info);
+}
+
+static inline int fanotify_info_file_fh_len(struct fanotify_info *info)
+{
+	if (!info->file_fh_totlen ||
+	    WARN_ON_ONCE(info->file_fh_totlen < FANOTIFY_FH_HDR_LEN))
+		return 0;
+
+	return info->file_fh_totlen - FANOTIFY_FH_HDR_LEN;
+}
+
+static inline struct fanotify_fh *fanotify_info_file_fh(struct fanotify_info *info)
+{
+	return (struct fanotify_fh *)FANOTIFY_FILE_FH_BUF(info);
+}
+
+static inline char *fanotify_info_name(struct fanotify_info *info)
+{
+	if (!info->name_len)
+		return NULL;
+
+	return FANOTIFY_NAME_BUF(info);
+}
+
+static inline char *fanotify_info_name2(struct fanotify_info *info)
+{
+	if (!info->name2_len)
+		return NULL;
+
+	return FANOTIFY_NAME2_BUF(info);
+}
+
+static inline void fanotify_info_init(struct fanotify_info *info)
+{
+	BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN + MAX_HANDLE_SZ > U8_MAX);
+	BUILD_BUG_ON(NAME_MAX > U8_MAX);
+
+	info->dir_fh_totlen = 0;
+	info->dir2_fh_totlen = 0;
+	info->file_fh_totlen = 0;
+	info->name_len = 0;
+	info->name2_len = 0;
+}
+
+/* These set/copy helpers MUST be called by order */
+static inline void fanotify_info_set_dir_fh(struct fanotify_info *info,
+					    unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->dir2_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->file_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->dir_fh_totlen = totlen;
+}
+
+static inline void fanotify_info_set_dir2_fh(struct fanotify_info *info,
+					     unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->file_fh_totlen > 0) ||
+	    WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->dir2_fh_totlen = totlen;
+}
+
+static inline void fanotify_info_set_file_fh(struct fanotify_info *info,
+					     unsigned int totlen)
+{
+	if (WARN_ON_ONCE(info->name_len > 0) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->file_fh_totlen = totlen;
+}
+
+static inline void fanotify_info_copy_name(struct fanotify_info *info,
+					   const struct qstr *name)
+{
+	if (WARN_ON_ONCE(name->len > NAME_MAX) ||
+	    WARN_ON_ONCE(info->name2_len > 0))
+		return;
+
+	info->name_len = name->len;
+	strscpy(fanotify_info_name(info), name->name, name->len + 1);
+}
+
+static inline void fanotify_info_copy_name2(struct fanotify_info *info,
+					    const struct qstr *name)
+{
+	if (WARN_ON_ONCE(name->len > NAME_MAX))
+		return;
+
+	info->name2_len = name->len;
+	strscpy(fanotify_info_name2(info), name->name, name->len + 1);
+}
+
+/*
+ * Common structure for fanotify events. Concrete structs are allocated in
+ * fanotify_handle_event() and freed when the information is retrieved by
+ * userspace. The type of event determines how it was allocated, how it will
+ * be freed and which concrete struct it may be cast to.
+ */
+enum fanotify_event_type {
+	FANOTIFY_EVENT_TYPE_FID, /* fixed length */
+	FANOTIFY_EVENT_TYPE_FID_NAME, /* variable length */
+	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_MNT,
+	__FANOTIFY_EVENT_TYPE_NUM
+};
+
+#define FANOTIFY_EVENT_TYPE_BITS \
+	(ilog2(__FANOTIFY_EVENT_TYPE_NUM - 1) + 1)
+#define FANOTIFY_EVENT_HASH_BITS \
+	(32 - FANOTIFY_EVENT_TYPE_BITS)
+
+struct fanotify_event {
+	struct fsnotify_event fse;
+	struct hlist_node merge_list;	/* List for hashed merge */
+	u32 mask;
+	struct {
+		unsigned int type : FANOTIFY_EVENT_TYPE_BITS;
+		unsigned int hash : FANOTIFY_EVENT_HASH_BITS;
+	};
+	struct pid *pid;
+};
+
+static inline void fanotify_init_event(struct fanotify_event *event,
+				       unsigned int hash, u32 mask)
+{
+	fsnotify_init_event(&event->fse);
+	INIT_HLIST_NODE(&event->merge_list);
+	event->hash = hash;
+	event->mask = mask;
+	event->pid = NULL;
+}
+
+#define FANOTIFY_INLINE_FH(name, size)					\
+struct {								\
+	struct fanotify_fh name;					\
+	/* Space for filehandle - access with fanotify_fh_buf() */	\
+	unsigned char _inline_fh_buf[size];				\
+}
+
+struct fanotify_fid_event {
+	struct fanotify_event fae;
+	__kernel_fsid_t fsid;
+
+	FANOTIFY_INLINE_FH(object_fh, FANOTIFY_INLINE_FH_LEN);
+};
+
+static inline struct fanotify_fid_event *
+FANOTIFY_FE(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_fid_event, fae);
+}
+
+struct fanotify_name_event {
+	struct fanotify_event fae;
+	__kernel_fsid_t fsid;
+	struct fanotify_info info;
+};
+
+static inline struct fanotify_name_event *
+FANOTIFY_NE(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_name_event, fae);
+}
+
+struct fanotify_error_event {
+	struct fanotify_event fae;
+	s32 error; /* Error reported by the Filesystem. */
+	u32 err_count; /* Suppressed errors count */
+
+	__kernel_fsid_t fsid; /* FSID this error refers to. */
+
+	FANOTIFY_INLINE_FH(object_fh, MAX_HANDLE_SZ);
+};
+
+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;
+}
+
+static inline struct fanotify_fh *fanotify_event_object_fh(
+						struct fanotify_event *event)
+{
+	if (event->type == FANOTIFY_EVENT_TYPE_FID)
+		return &FANOTIFY_FE(event)->object_fh;
+	else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
+		return fanotify_info_file_fh(&FANOTIFY_NE(event)->info);
+	else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
+		return &FANOTIFY_EE(event)->object_fh;
+	else
+		return NULL;
+}
+
+static inline struct fanotify_info *fanotify_event_info(
+						struct fanotify_event *event)
+{
+	if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
+		return &FANOTIFY_NE(event)->info;
+	else
+		return NULL;
+}
+
+static inline int fanotify_event_object_fh_len(struct fanotify_event *event)
+{
+	struct fanotify_info *info = fanotify_event_info(event);
+	struct fanotify_fh *fh = fanotify_event_object_fh(event);
+
+	if (info)
+		return info->file_fh_totlen ? fh->len : 0;
+	else
+		return fh ? fh->len : 0;
+}
+
+static inline int fanotify_event_dir_fh_len(struct fanotify_event *event)
+{
+	struct fanotify_info *info = fanotify_event_info(event);
+
+	return info ? fanotify_info_dir_fh_len(info) : 0;
+}
+
+static inline int fanotify_event_dir2_fh_len(struct fanotify_event *event)
+{
+	struct fanotify_info *info = fanotify_event_info(event);
+
+	return info ? fanotify_info_dir2_fh_len(info) : 0;
+}
+
+static inline bool fanotify_event_has_object_fh(struct fanotify_event *event)
+{
+	/* For error events, even zeroed fh are reported. */
+	if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
+		return true;
+	return fanotify_event_object_fh_len(event) > 0;
+}
+
+static inline bool fanotify_event_has_dir_fh(struct fanotify_event *event)
+{
+	return fanotify_event_dir_fh_len(event) > 0;
+}
+
+static inline bool fanotify_event_has_dir2_fh(struct fanotify_event *event)
+{
+	return fanotify_event_dir2_fh_len(event) > 0;
+}
+
+static inline bool fanotify_event_has_any_dir_fh(struct fanotify_event *event)
+{
+	return fanotify_event_has_dir_fh(event) ||
+		fanotify_event_has_dir2_fh(event);
+}
+
+struct fanotify_path_event {
+	struct fanotify_event fae;
+	struct path path;
+};
+
+struct fanotify_mnt_event {
+	struct fanotify_event fae;
+	u64 mnt_id;
+};
+
+static inline struct fanotify_path_event *
+FANOTIFY_PE(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_path_event, fae);
+}
+
+static inline struct fanotify_mnt_event *
+FANOTIFY_ME(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_mnt_event, fae);
+}
+
+/*
+ * 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 {
+	struct fanotify_event fae;
+	struct path path;
+	const loff_t *ppos;		/* optional file range info */
+	size_t count;
+	u32 response;			/* userspace answer to the event */
+	unsigned short state;		/* state of the event */
+	unsigned short watchdog_cnt;	/* already scanned by watchdog? */
+	int fd;		/* fd we passed to userspace for this event */
+	pid_t recv_pid;	/* pid of task receiving the event */
+	union {
+		struct fanotify_response_info_header hdr;
+		struct fanotify_response_info_audit_rule audit_rule;
+	};
+};
+
+static inline struct fanotify_perm_event *
+FANOTIFY_PERM(struct fanotify_event *event)
+{
+	return container_of(event, struct fanotify_perm_event, fae);
+}
+
+static inline bool fanotify_is_perm_event(u32 mask)
+{
+	return IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS) &&
+		mask & FANOTIFY_PERM_EVENTS;
+}
+
+static inline bool fanotify_event_has_access_range(struct fanotify_event *event)
+{
+	if (!(event->mask & FANOTIFY_PRE_CONTENT_EVENTS))
+		return false;
+
+	return FANOTIFY_PERM(event)->ppos;
+}
+
+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 & FAN_FS_ERROR;
+}
+
+static inline bool fanotify_is_mnt_event(u32 mask)
+{
+	return mask & (FAN_MNT_ATTACH | FAN_MNT_DETACH);
+}
+
+static inline const struct path *fanotify_event_path(struct fanotify_event *event)
+{
+	if (event->type == FANOTIFY_EVENT_TYPE_PATH)
+		return &FANOTIFY_PE(event)->path;
+	else if (event->type == FANOTIFY_EVENT_TYPE_PATH_PERM)
+		return &FANOTIFY_PERM(event)->path;
+	else
+		return NULL;
+}
+
+/*
+ * Use 128 size hash table to speed up events merge.
+ */
+#define FANOTIFY_HTABLE_BITS	(7)
+#define FANOTIFY_HTABLE_SIZE	(1 << FANOTIFY_HTABLE_BITS)
+#define FANOTIFY_HTABLE_MASK	(FANOTIFY_HTABLE_SIZE - 1)
+
+/*
+ * Permission events and overflow event do not get merged - don't hash them.
+ */
+static inline bool fanotify_is_hashed_event(u32 mask)
+{
+	return !(fanotify_is_perm_event(mask) ||
+		 fsnotify_is_overflow_event(mask));
+}
+
+static inline unsigned int fanotify_event_hash_bucket(
+						struct fsnotify_group *group,
+						struct fanotify_event *event)
+{
+	return event->hash & FANOTIFY_HTABLE_MASK;
+}
+
+struct fanotify_mark {
+	struct fsnotify_mark fsn_mark;
+	__kernel_fsid_t fsid;
+};
+
+static inline struct fanotify_mark *FANOTIFY_MARK(struct fsnotify_mark *mark)
+{
+	return container_of(mark, struct fanotify_mark, fsn_mark);
+}
+
+static inline bool fanotify_fsid_equal(__kernel_fsid_t *fsid1,
+				       __kernel_fsid_t *fsid2)
+{
+	return fsid1->val[0] == fsid2->val[0] && fsid1->val[1] == fsid2->val[1];
+}
+
+static inline unsigned int fanotify_mark_user_flags(struct fsnotify_mark *mark)
+{
+	unsigned int mflags = 0;
+
+	if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
+		mflags |= FAN_MARK_IGNORED_SURV_MODIFY;
+	if (mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)
+		mflags |= FAN_MARK_EVICTABLE;
+	if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
+		mflags |= FAN_MARK_IGNORE;
+
+	return mflags;
+}
+
+static inline u32 fanotify_get_response_errno(int res)
+{
+	return (res >> FAN_ERRNO_SHIFT) & FAN_ERRNO_MASK;
+}