summaryrefslogtreecommitdiff
path: root/fs/notify/fanotify/fanotify.h
blob: 35bfbf4a7aac4b74e6f88bbe590d9cbb11c7e15c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/fsnotify_backend.h>
#include <linux/path.h>
#include <linux/slab.h>
#include <linux/exportfs.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;

/* 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)

struct fanotify_fh {
	unsigned char buf[FANOTIFY_INLINE_FH_LEN];
	u8 type;
	u8 len;
} __aligned(4);

static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh)
{
	return fh->len > FANOTIFY_INLINE_FH_LEN;
}

static inline char **fanotify_fh_ext_buf_ptr(struct fanotify_fh *fh)
{
	BUILD_BUG_ON(__alignof__(char *) - 4 + sizeof(char *) >
		     FANOTIFY_INLINE_FH_LEN);
	return (char **)ALIGN((unsigned long)(fh->buf), __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->buf;
}

/*
 * 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,
};

struct fanotify_event {
	struct fsnotify_event fse;
	u32 mask;
	enum fanotify_event_type type;
	struct pid *pid;
};

struct fanotify_fid_event {
	struct fanotify_event fae;
	__kernel_fsid_t fsid;
	struct fanotify_fh object_fh;
};

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_fh dir_fh;
	u8 name_len;
	char name[0];
};

static inline struct fanotify_name_event *
FANOTIFY_NE(struct fanotify_event *event)
{
	return container_of(event, struct fanotify_name_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
		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
		return NULL;
}

static inline struct fanotify_fh *fanotify_event_dir_fh(
						struct fanotify_event *event)
{
	if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
		return &FANOTIFY_NE(event)->dir_fh;
	else
		return NULL;
}

static inline int fanotify_event_object_fh_len(struct fanotify_event *event)
{
	struct fanotify_fh *fh = fanotify_event_object_fh(event);

	return fh ? fh->len : 0;
}

static inline bool fanotify_event_has_name(struct fanotify_event *event)
{
	return event->type == FANOTIFY_EVENT_TYPE_FID_NAME;
}

static inline int fanotify_event_name_len(struct fanotify_event *event)
{
	return fanotify_event_has_name(event) ?
		FANOTIFY_NE(event)->name_len : 0;
}

struct fanotify_path_event {
	struct fanotify_event fae;
	struct path path;
};

static inline struct fanotify_path_event *
FANOTIFY_PE(struct fanotify_event *event)
{
	return container_of(event, struct fanotify_path_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;
	unsigned short response;	/* userspace answer to the event */
	unsigned short state;		/* state of the event */
	int fd;		/* fd we passed to userspace for this event */
};

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 struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)
{
	return container_of(fse, struct fanotify_event, fse);
}

static inline bool fanotify_event_has_path(struct fanotify_event *event)
{
	return event->type == FANOTIFY_EVENT_TYPE_PATH ||
		event->type == FANOTIFY_EVENT_TYPE_PATH_PERM;
}

static inline 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;
}

struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
					    struct inode *inode, u32 mask,
					    const void *data, int data_type,
					    const struct qstr *file_name,
					    __kernel_fsid_t *fsid);