1 // SPDX-License-Identifier: GPL-2.0-only <<
2 /* 1 /*
3 * Copyright 2013-2017 by PaX Team <pageexec@f 2 * Copyright 2013-2017 by PaX Team <pageexec@freemail.hu>
>> 3 * Licensed under the GPL v2
4 * 4 *
5 * Note: the choice of the license means that 5 * Note: the choice of the license means that the compilation process is
6 * NOT 'eligible' as defined by gcc's li 6 * NOT 'eligible' as defined by gcc's library exception to the GPL v3,
7 * but for the kernel it doesn't matter 7 * but for the kernel it doesn't matter since it doesn't link against
8 * any of the gcc libraries 8 * any of the gcc libraries
9 * 9 *
10 * gcc plugin to forcibly initialize certain l 10 * gcc plugin to forcibly initialize certain local variables that could
11 * otherwise leak kernel stack to userland if 11 * otherwise leak kernel stack to userland if they aren't properly initialized
12 * by later code 12 * by later code
13 * 13 *
14 * Homepage: https://pax.grsecurity.net/ !! 14 * Homepage: http://pax.grsecurity.net/
15 * 15 *
16 * Options: 16 * Options:
17 * -fplugin-arg-structleak_plugin-disable 17 * -fplugin-arg-structleak_plugin-disable
18 * -fplugin-arg-structleak_plugin-verbose 18 * -fplugin-arg-structleak_plugin-verbose
19 * -fplugin-arg-structleak_plugin-byref <<
20 * -fplugin-arg-structleak_plugin-byref-all 19 * -fplugin-arg-structleak_plugin-byref-all
21 * 20 *
22 * Usage: 21 * Usage:
23 * $ # for 4.5/4.6/C based 4.7 22 * $ # for 4.5/4.6/C based 4.7
24 * $ gcc -I`gcc -print-file-name=plugin`/inclu 23 * $ gcc -I`gcc -print-file-name=plugin`/include -I`gcc -print-file-name=plugin`/include/c-family -fPIC -shared -O2 -o structleak_plugin.so structleak_plugin.c
25 * $ # for C++ based 4.7/4.8+ 24 * $ # for C++ based 4.7/4.8+
26 * $ g++ -I`g++ -print-file-name=plugin`/inclu 25 * $ g++ -I`g++ -print-file-name=plugin`/include -I`g++ -print-file-name=plugin`/include/c-family -fPIC -shared -O2 -o structleak_plugin.so structleak_plugin.c
27 * $ gcc -fplugin=./structleak_plugin.so test. 26 * $ gcc -fplugin=./structleak_plugin.so test.c -O2
28 * 27 *
29 * TODO: eliminate redundant initializers 28 * TODO: eliminate redundant initializers
>> 29 * increase type coverage
30 */ 30 */
31 31
32 #include "gcc-common.h" 32 #include "gcc-common.h"
33 33
34 /* unused C type flag in all versions 4.5-6 */ 34 /* unused C type flag in all versions 4.5-6 */
35 #define TYPE_USERSPACE(TYPE) TYPE_LANG_FLAG_5( 35 #define TYPE_USERSPACE(TYPE) TYPE_LANG_FLAG_5(TYPE)
36 36
37 __visible int plugin_is_GPL_compatible; 37 __visible int plugin_is_GPL_compatible;
38 38
39 static struct plugin_info structleak_plugin_in 39 static struct plugin_info structleak_plugin_info = {
40 .version = PLUGIN_VERSION, !! 40 .version = "201607271510vanilla",
41 .help = "disable\tdo not act 41 .help = "disable\tdo not activate plugin\n"
42 "byref\tinit structs !! 42 "verbose\tprint all initialized variables\n",
43 "byref-all\tinit any <<
44 "verbose\tprint all <<
45 }; 43 };
46 44
47 #define BYREF_STRUCT 1 <<
48 #define BYREF_ALL 2 <<
49 <<
50 static bool verbose; 45 static bool verbose;
51 static int byref; !! 46 static bool byref_all;
52 47
53 static tree handle_user_attribute(tree *node, 48 static tree handle_user_attribute(tree *node, tree name, tree args, int flags, bool *no_add_attrs)
54 { 49 {
55 *no_add_attrs = true; 50 *no_add_attrs = true;
56 51
57 /* check for types? for now accept eve 52 /* check for types? for now accept everything linux has to offer */
58 if (TREE_CODE(*node) != FIELD_DECL) 53 if (TREE_CODE(*node) != FIELD_DECL)
59 return NULL_TREE; 54 return NULL_TREE;
60 55
61 *no_add_attrs = false; 56 *no_add_attrs = false;
62 return NULL_TREE; 57 return NULL_TREE;
63 } 58 }
64 59
65 static struct attribute_spec user_attr = { }; 60 static struct attribute_spec user_attr = { };
66 61
67 static void register_attributes(void *event_da 62 static void register_attributes(void *event_data, void *data)
68 { 63 {
69 user_attr.name = "use 64 user_attr.name = "user";
70 user_attr.handler = hand 65 user_attr.handler = handle_user_attribute;
>> 66 #if BUILDING_GCC_VERSION >= 4007
71 user_attr.affects_type_identity = true 67 user_attr.affects_type_identity = true;
>> 68 #endif
72 69
73 register_attribute(&user_attr); 70 register_attribute(&user_attr);
74 } 71 }
75 72
76 static tree get_field_type(tree field) 73 static tree get_field_type(tree field)
77 { 74 {
78 return strip_array_types(TREE_TYPE(fie 75 return strip_array_types(TREE_TYPE(field));
79 } 76 }
80 77
81 static bool is_userspace_type(tree type) 78 static bool is_userspace_type(tree type)
82 { 79 {
83 tree field; 80 tree field;
84 81
85 for (field = TYPE_FIELDS(type); field; 82 for (field = TYPE_FIELDS(type); field; field = TREE_CHAIN(field)) {
86 tree fieldtype = get_field_typ 83 tree fieldtype = get_field_type(field);
87 enum tree_code code = TREE_COD 84 enum tree_code code = TREE_CODE(fieldtype);
88 85
89 if (code == RECORD_TYPE || cod 86 if (code == RECORD_TYPE || code == UNION_TYPE)
90 if (is_userspace_type( 87 if (is_userspace_type(fieldtype))
91 return true; 88 return true;
92 89
93 if (lookup_attribute("user", D 90 if (lookup_attribute("user", DECL_ATTRIBUTES(field)))
94 return true; 91 return true;
95 } 92 }
96 return false; 93 return false;
97 } 94 }
98 95
99 static void finish_type(void *event_data, void 96 static void finish_type(void *event_data, void *data)
100 { 97 {
101 tree type = (tree)event_data; 98 tree type = (tree)event_data;
102 99
103 if (type == NULL_TREE || type == error 100 if (type == NULL_TREE || type == error_mark_node)
104 return; 101 return;
105 102
>> 103 #if BUILDING_GCC_VERSION >= 5000
106 if (TREE_CODE(type) == ENUMERAL_TYPE) 104 if (TREE_CODE(type) == ENUMERAL_TYPE)
107 return; 105 return;
>> 106 #endif
108 107
109 if (TYPE_USERSPACE(type)) 108 if (TYPE_USERSPACE(type))
110 return; 109 return;
111 110
112 if (is_userspace_type(type)) 111 if (is_userspace_type(type))
113 TYPE_USERSPACE(type) = 1; 112 TYPE_USERSPACE(type) = 1;
114 } 113 }
115 114
116 static void initialize(tree var) 115 static void initialize(tree var)
117 { 116 {
118 basic_block bb; 117 basic_block bb;
119 gimple_stmt_iterator gsi; 118 gimple_stmt_iterator gsi;
120 tree initializer; 119 tree initializer;
121 gimple init_stmt; 120 gimple init_stmt;
122 tree type; <<
123 121
124 /* this is the original entry bb befor 122 /* this is the original entry bb before the forced split */
125 bb = single_succ(ENTRY_BLOCK_PTR_FOR_F 123 bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
126 124
127 /* first check if variable is already 125 /* first check if variable is already initialized, warn otherwise */
128 for (gsi = gsi_start_bb(bb); !gsi_end_ 126 for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) {
129 gimple stmt = gsi_stmt(gsi); 127 gimple stmt = gsi_stmt(gsi);
130 tree rhs1; 128 tree rhs1;
131 129
132 /* we're looking for an assign 130 /* we're looking for an assignment of a single rhs... */
133 if (!gimple_assign_single_p(st 131 if (!gimple_assign_single_p(stmt))
134 continue; 132 continue;
135 rhs1 = gimple_assign_rhs1(stmt 133 rhs1 = gimple_assign_rhs1(stmt);
>> 134 #if BUILDING_GCC_VERSION >= 4007
136 /* ... of a non-clobbering exp 135 /* ... of a non-clobbering expression... */
137 if (TREE_CLOBBER_P(rhs1)) 136 if (TREE_CLOBBER_P(rhs1))
138 continue; 137 continue;
>> 138 #endif
139 /* ... to our variable... */ 139 /* ... to our variable... */
140 if (gimple_get_lhs(stmt) != va 140 if (gimple_get_lhs(stmt) != var)
141 continue; 141 continue;
142 /* if it's an initializer then 142 /* if it's an initializer then we're good */
143 if (TREE_CODE(rhs1) == CONSTRU 143 if (TREE_CODE(rhs1) == CONSTRUCTOR)
144 return; 144 return;
145 } 145 }
146 146
147 /* these aren't the 0days you're looki 147 /* these aren't the 0days you're looking for */
148 if (verbose) 148 if (verbose)
149 inform(DECL_SOURCE_LOCATION(va 149 inform(DECL_SOURCE_LOCATION(var),
150 "%s variable will be f 150 "%s variable will be forcibly initialized",
151 (byref && TREE_ADDRESS !! 151 (byref_all && TREE_ADDRESSABLE(var)) ? "byref"
152 !! 152 : "userspace");
153 153
154 /* build the initializer expression */ 154 /* build the initializer expression */
155 type = TREE_TYPE(var); !! 155 initializer = build_constructor(TREE_TYPE(var), NULL);
156 if (AGGREGATE_TYPE_P(type)) <<
157 initializer = build_constructo <<
158 else <<
159 initializer = fold_convert(typ <<
160 156
161 /* build the initializer stmt */ 157 /* build the initializer stmt */
162 init_stmt = gimple_build_assign(var, i 158 init_stmt = gimple_build_assign(var, initializer);
163 gsi = gsi_after_labels(single_succ(ENT 159 gsi = gsi_after_labels(single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
164 gsi_insert_before(&gsi, init_stmt, GSI 160 gsi_insert_before(&gsi, init_stmt, GSI_NEW_STMT);
165 update_stmt(init_stmt); 161 update_stmt(init_stmt);
166 } 162 }
167 163
168 static unsigned int structleak_execute(void) 164 static unsigned int structleak_execute(void)
169 { 165 {
170 basic_block bb; 166 basic_block bb;
>> 167 unsigned int ret = 0;
171 tree var; 168 tree var;
172 unsigned int i; 169 unsigned int i;
173 170
174 /* split the first bb where we can put 171 /* split the first bb where we can put the forced initializers */
175 gcc_assert(single_succ_p(ENTRY_BLOCK_P 172 gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
176 bb = single_succ(ENTRY_BLOCK_PTR_FOR_F 173 bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
177 if (!single_pred_p(bb)) { 174 if (!single_pred_p(bb)) {
178 split_edge(single_succ_edge(EN 175 split_edge(single_succ_edge(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
179 gcc_assert(single_succ_p(ENTRY 176 gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
180 } 177 }
181 178
182 /* enumerate all local variables and f 179 /* enumerate all local variables and forcibly initialize our targets */
183 FOR_EACH_LOCAL_DECL(cfun, i, var) { 180 FOR_EACH_LOCAL_DECL(cfun, i, var) {
184 tree type = TREE_TYPE(var); 181 tree type = TREE_TYPE(var);
185 182
186 gcc_assert(DECL_P(var)); 183 gcc_assert(DECL_P(var));
187 if (!auto_var_in_fn_p(var, cur 184 if (!auto_var_in_fn_p(var, current_function_decl))
188 continue; 185 continue;
189 186
190 /* only care about structure t !! 187 /* only care about structure types */
191 if (byref != BYREF_ALL && TREE !! 188 if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE)
192 continue; 189 continue;
193 190
194 /* if the type is of interest, 191 /* if the type is of interest, examine the variable */
195 if (TYPE_USERSPACE(type) || 192 if (TYPE_USERSPACE(type) ||
196 (byref && TREE_ADDRESSABLE !! 193 (byref_all && TREE_ADDRESSABLE(var)))
197 initialize(var); 194 initialize(var);
198 } 195 }
199 196
200 return 0; !! 197 return ret;
201 } 198 }
202 199
203 #define PASS_NAME structleak 200 #define PASS_NAME structleak
204 #define NO_GATE 201 #define NO_GATE
205 #define PROPERTIES_REQUIRED PROP_cfg 202 #define PROPERTIES_REQUIRED PROP_cfg
206 #define TODO_FLAGS_FINISH TODO_verify_il | TOD 203 #define TODO_FLAGS_FINISH TODO_verify_il | TODO_verify_ssa | TODO_verify_stmts | TODO_dump_func | TODO_remove_unused_locals | TODO_update_ssa | TODO_ggc_collect | TODO_verify_flow
207 #include "gcc-generate-gimple-pass.h" 204 #include "gcc-generate-gimple-pass.h"
208 205
209 __visible int plugin_init(struct plugin_name_a 206 __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
210 { 207 {
211 int i; 208 int i;
212 const char * const plugin_name = plugi 209 const char * const plugin_name = plugin_info->base_name;
213 const int argc = plugin_info->argc; 210 const int argc = plugin_info->argc;
214 const struct plugin_argument * const a 211 const struct plugin_argument * const argv = plugin_info->argv;
215 bool enable = true; 212 bool enable = true;
216 213
217 PASS_INFO(structleak, "early_optimizat 214 PASS_INFO(structleak, "early_optimizations", 1, PASS_POS_INSERT_BEFORE);
218 215
219 if (!plugin_default_version_check(vers 216 if (!plugin_default_version_check(version, &gcc_version)) {
220 error(G_("incompatible gcc/plu 217 error(G_("incompatible gcc/plugin versions"));
221 return 1; 218 return 1;
222 } 219 }
223 220
224 if (strncmp(lang_hooks.name, "GNU C", 221 if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) {
225 inform(UNKNOWN_LOCATION, G_("% 222 inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name);
226 enable = false; 223 enable = false;
227 } 224 }
228 225
229 for (i = 0; i < argc; ++i) { 226 for (i = 0; i < argc; ++i) {
230 if (!strcmp(argv[i].key, "disa 227 if (!strcmp(argv[i].key, "disable")) {
231 enable = false; 228 enable = false;
232 continue; 229 continue;
233 } 230 }
234 if (!strcmp(argv[i].key, "verb 231 if (!strcmp(argv[i].key, "verbose")) {
235 verbose = true; 232 verbose = true;
236 continue; 233 continue;
237 } 234 }
238 if (!strcmp(argv[i].key, "byre <<
239 byref = BYREF_STRUCT; <<
240 continue; <<
241 } <<
242 if (!strcmp(argv[i].key, "byre 235 if (!strcmp(argv[i].key, "byref-all")) {
243 byref = BYREF_ALL; !! 236 byref_all = true;
244 continue; 237 continue;
245 } 238 }
246 error(G_("unknown option '-fpl 239 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
247 } 240 }
248 241
249 register_callback(plugin_name, PLUGIN_ 242 register_callback(plugin_name, PLUGIN_INFO, NULL, &structleak_plugin_info);
250 if (enable) { 243 if (enable) {
251 register_callback(plugin_name, 244 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &structleak_pass_info);
252 register_callback(plugin_name, 245 register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL);
253 } 246 }
254 register_callback(plugin_name, PLUGIN_ 247 register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL);
255 248
256 return 0; 249 return 0;
257 } 250 }
258 251
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