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
|
// SPDX-License-Identifier: GPL-3.0-or-later
/* seitan - Syscall Expressive Interpreter, Transformer and Notifier
*
* cooker/emit.c - Generate gluten (bytecode) instructions and read-only data
*
* Copyright 2023 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
#include "cooker.h"
#include "gluten.h"
#include "util.h"
#include "emit.h"
static const char *type_str[] = {
"UNDEF", "NONE",
"INT", "INTMASK", "INTFLAGS",
"U32", "U32MASK", "U32FLAGS",
"U64", "U64MASK", "U64FLAGS",
"LONG", "LONGMASK", "LONGFLAGS",
"STRING",
"STRUCT", "SELECT",
"PID",
"PORT", "IPV4", "IPV6",
"FDPATH",
NULL
};
static const char *cmp_type_str[] = {
"EQ", "NE", "GT", "GE", "LT", "LE", NULL
};
/**
* emit_nr() - Emit OP_NR instruction: jump on syscall mismatch
* @g: gluten context
* @number: Pointer to system call number
*/
void emit_nr(struct gluten_ctx *g, struct gluten_offset number)
{
struct op *op = (struct op *)gluten_ptr(&g->g, g->ip);
struct op_nr *nr = &op->op.nr;
op->type = OP_NR;
nr->nr = number;
nr->no_match.type = OFFSET_INSTRUCTION;
nr->no_match.offset = JUMP_NEXT_BLOCK;
debug(" %i: OP_NR: if syscall number is not %li, jump to %s",
g->ip.offset, number, jump_name[nr->no_match.offset]);
if (++g->ip.offset > INST_MAX)
die("Too many instructions");
}
/**
* emit_load() - Emit OP_LOAD instruction: dereference and copy syscall argument
* @g: gluten context
* @dst: gluten destination to copy dereferenced data
* @index: Index of system call argument
* @len: Length of data item pointed by reference
*/
void emit_load(struct gluten_ctx *g, struct gluten_offset dst,
int index, size_t len)
{
struct op *op = (struct op *)gluten_ptr(&g->g, g->ip);
struct op_load *load = &op->op.load;
op->type = OP_LOAD;
load->src.type = OFFSET_SECCOMP_DATA;
load->src.offset = index;
load->dst = dst;
debug(" %i: OP_LOAD: #%i < args[%i] (size: %lu)",
g->ip.offset, dst.offset, index, len);
if (++g->ip.offset > INST_MAX)
die("Too many instructions");
}
/**
* emit_cmp(): Emit OP_CMP instruction: compare data from two offsets
* @g: gluten context
* @cmp_type: Type of comparison
* @x: gluten pointer to first operand of comparison
* @y: gluten pointer to second operand of comparison
* @size: Size of comparison
* @jmp: Jump direction if comparison is true
*/
void emit_cmp(struct gluten_ctx *g, enum op_cmp_type cmp_type,
struct gluten_offset x, struct gluten_offset y, size_t size,
enum jump_type jmp)
{
struct op *op = (struct op *)gluten_ptr(&g->g, g->ip);
struct op_cmp *cmp = &op->op.cmp;
op->type = OP_CMP;
cmp->x = x;
cmp->y = y;
cmp->size = size;
cmp->cmp = cmp_type;
cmp->jmp.type = OFFSET_INSTRUCTION;
cmp->jmp.offset = jmp;
debug(" %i: OP_CMP: if %s: #%lu %s (size: %lu) %s: #%lu, jump to %s",
g->ip.offset,
gluten_offset_name[x.type], x.offset,
cmp_type_str[cmp_type], size,
gluten_offset_name[y.type], y.offset,
jump_name[jmp]);
if (++g->ip.offset > INST_MAX)
die("Too many instructions");
}
/**
* emit_cmp_field() - Emit OP_CMP for a given field type
* @g: gluten context
* @cmp: Type of comparison
* @field: Description of field from system call model
* @x: gluten pointer to first operand of comparison
* @y: gluten pointer to second operand of comparison
* @jmp: Jump direction if comparison is true
*/
void emit_cmp_field(struct gluten_ctx *g, enum op_cmp_type cmp,
struct field *field,
struct gluten_offset x, struct gluten_offset y,
enum jump_type jmp)
{
emit_cmp(g, cmp, x, y,
field->strlen ? field->strlen : gluten_size[field->type],
jmp);
}
struct gluten_offset emit_data(struct gluten_ctx *g, enum type type,
size_t str_len, union value *value)
{
void *p = gluten_ptr(&g->g, g->cp);
struct gluten_offset ret = g->cp;
switch (type) {
case INT:
if (g->cp.offset + sizeof(int) > RO_DATA_SIZE)
die(" Read-only data section exceeded");
*(int *)p = value->v_int;
debug(" C#%i: (%s) %i", g->cp.offset, type_str[type],
value->v_int);
g->cp.offset += sizeof(int);
break;
case STRING:
if (g->cp.offset + str_len > RO_DATA_SIZE)
die(" Read-only data section exceeded");
strncpy(p, value->v_str, str_len);
debug(" C#%i: (%s:%i) %s", g->cp.offset, type_str[type],
str_len, value->v_str);
g->cp.offset += str_len;
break;
default:
;
}
return ret;
}
static void gluten_link(struct gluten_ctx *g, enum jump_type type,
struct op *start)
{
struct gluten_offset *jmp;
struct op *op;
for (op = (struct op *)start; op->type; op++) {
switch (op->type) {
case OP_NR:
jmp = &op->op.nr.no_match;
break;
case OP_CMP:
jmp = &op->op.cmp.jmp;
break;
default:
continue;
}
if (jmp->offset == type) {
jmp->offset = g->ip.offset;
debug(" linked jump of instruction #%i to #%i",
op - (struct op *)g->g.inst, g->ip.offset);
}
}
}
void link_block(struct gluten_ctx *g)
{
debug(" Linking block...");
gluten_link(g, JUMP_NEXT_BLOCK, (struct op *)gluten_ptr(&g->g, g->lr));
}
void link_match(struct gluten_ctx *g)
{
debug(" Linking match...");
gluten_link(g, JUMP_NEXT_MATCH, (struct op *)gluten_ptr(&g->g, g->mr));
}
|
