Merge branch 'core/speculation' of git://git.kernel.org/pub/scm/linux/kernel/git...
[sfrench/cifs-2.6.git] / arch / powerpc / kernel / security.c
1 // SPDX-License-Identifier: GPL-2.0+
2 //
3 // Security related flags and so on.
4 //
5 // Copyright 2018, Michael Ellerman, IBM Corporation.
6
7 #include <linux/cpu.h>
8 #include <linux/kernel.h>
9 #include <linux/device.h>
10 #include <linux/seq_buf.h>
11
12 #include <asm/asm-prototypes.h>
13 #include <asm/code-patching.h>
14 #include <asm/debugfs.h>
15 #include <asm/security_features.h>
16 #include <asm/setup.h>
17
18
19 unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
20
21 enum count_cache_flush_type {
22         COUNT_CACHE_FLUSH_NONE  = 0x1,
23         COUNT_CACHE_FLUSH_SW    = 0x2,
24         COUNT_CACHE_FLUSH_HW    = 0x4,
25 };
26 static enum count_cache_flush_type count_cache_flush_type = COUNT_CACHE_FLUSH_NONE;
27
28 bool barrier_nospec_enabled;
29 static bool no_nospec;
30 static bool btb_flush_enabled;
31 #ifdef CONFIG_PPC_FSL_BOOK3E
32 static bool no_spectrev2;
33 #endif
34
35 static void enable_barrier_nospec(bool enable)
36 {
37         barrier_nospec_enabled = enable;
38         do_barrier_nospec_fixups(enable);
39 }
40
41 void setup_barrier_nospec(void)
42 {
43         bool enable;
44
45         /*
46          * It would make sense to check SEC_FTR_SPEC_BAR_ORI31 below as well.
47          * But there's a good reason not to. The two flags we check below are
48          * both are enabled by default in the kernel, so if the hcall is not
49          * functional they will be enabled.
50          * On a system where the host firmware has been updated (so the ori
51          * functions as a barrier), but on which the hypervisor (KVM/Qemu) has
52          * not been updated, we would like to enable the barrier. Dropping the
53          * check for SEC_FTR_SPEC_BAR_ORI31 achieves that. The only downside is
54          * we potentially enable the barrier on systems where the host firmware
55          * is not updated, but that's harmless as it's a no-op.
56          */
57         enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
58                  security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);
59
60         if (!no_nospec && !cpu_mitigations_off())
61                 enable_barrier_nospec(enable);
62 }
63
64 static int __init handle_nospectre_v1(char *p)
65 {
66         no_nospec = true;
67
68         return 0;
69 }
70 early_param("nospectre_v1", handle_nospectre_v1);
71
72 #ifdef CONFIG_DEBUG_FS
73 static int barrier_nospec_set(void *data, u64 val)
74 {
75         switch (val) {
76         case 0:
77         case 1:
78                 break;
79         default:
80                 return -EINVAL;
81         }
82
83         if (!!val == !!barrier_nospec_enabled)
84                 return 0;
85
86         enable_barrier_nospec(!!val);
87
88         return 0;
89 }
90
91 static int barrier_nospec_get(void *data, u64 *val)
92 {
93         *val = barrier_nospec_enabled ? 1 : 0;
94         return 0;
95 }
96
97 DEFINE_SIMPLE_ATTRIBUTE(fops_barrier_nospec,
98                         barrier_nospec_get, barrier_nospec_set, "%llu\n");
99
100 static __init int barrier_nospec_debugfs_init(void)
101 {
102         debugfs_create_file("barrier_nospec", 0600, powerpc_debugfs_root, NULL,
103                             &fops_barrier_nospec);
104         return 0;
105 }
106 device_initcall(barrier_nospec_debugfs_init);
107 #endif /* CONFIG_DEBUG_FS */
108
109 #ifdef CONFIG_PPC_FSL_BOOK3E
110 static int __init handle_nospectre_v2(char *p)
111 {
112         no_spectrev2 = true;
113
114         return 0;
115 }
116 early_param("nospectre_v2", handle_nospectre_v2);
117 void setup_spectre_v2(void)
118 {
119         if (no_spectrev2 || cpu_mitigations_off())
120                 do_btb_flush_fixups();
121         else
122                 btb_flush_enabled = true;
123 }
124 #endif /* CONFIG_PPC_FSL_BOOK3E */
125
126 #ifdef CONFIG_PPC_BOOK3S_64
127 ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
128 {
129         bool thread_priv;
130
131         thread_priv = security_ftr_enabled(SEC_FTR_L1D_THREAD_PRIV);
132
133         if (rfi_flush || thread_priv) {
134                 struct seq_buf s;
135                 seq_buf_init(&s, buf, PAGE_SIZE - 1);
136
137                 seq_buf_printf(&s, "Mitigation: ");
138
139                 if (rfi_flush)
140                         seq_buf_printf(&s, "RFI Flush");
141
142                 if (rfi_flush && thread_priv)
143                         seq_buf_printf(&s, ", ");
144
145                 if (thread_priv)
146                         seq_buf_printf(&s, "L1D private per thread");
147
148                 seq_buf_printf(&s, "\n");
149
150                 return s.len;
151         }
152
153         if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
154             !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
155                 return sprintf(buf, "Not affected\n");
156
157         return sprintf(buf, "Vulnerable\n");
158 }
159 #endif
160
161 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
162 {
163         struct seq_buf s;
164
165         seq_buf_init(&s, buf, PAGE_SIZE - 1);
166
167         if (security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR)) {
168                 if (barrier_nospec_enabled)
169                         seq_buf_printf(&s, "Mitigation: __user pointer sanitization");
170                 else
171                         seq_buf_printf(&s, "Vulnerable");
172
173                 if (security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31))
174                         seq_buf_printf(&s, ", ori31 speculation barrier enabled");
175
176                 seq_buf_printf(&s, "\n");
177         } else
178                 seq_buf_printf(&s, "Not affected\n");
179
180         return s.len;
181 }
182
183 ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
184 {
185         struct seq_buf s;
186         bool bcs, ccd;
187
188         seq_buf_init(&s, buf, PAGE_SIZE - 1);
189
190         bcs = security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED);
191         ccd = security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED);
192
193         if (bcs || ccd) {
194                 seq_buf_printf(&s, "Mitigation: ");
195
196                 if (bcs)
197                         seq_buf_printf(&s, "Indirect branch serialisation (kernel only)");
198
199                 if (bcs && ccd)
200                         seq_buf_printf(&s, ", ");
201
202                 if (ccd)
203                         seq_buf_printf(&s, "Indirect branch cache disabled");
204         } else if (count_cache_flush_type != COUNT_CACHE_FLUSH_NONE) {
205                 seq_buf_printf(&s, "Mitigation: Software count cache flush");
206
207                 if (count_cache_flush_type == COUNT_CACHE_FLUSH_HW)
208                         seq_buf_printf(&s, " (hardware accelerated)");
209         } else if (btb_flush_enabled) {
210                 seq_buf_printf(&s, "Mitigation: Branch predictor state flush");
211         } else {
212                 seq_buf_printf(&s, "Vulnerable");
213         }
214
215         seq_buf_printf(&s, "\n");
216
217         return s.len;
218 }
219
220 #ifdef CONFIG_PPC_BOOK3S_64
221 /*
222  * Store-forwarding barrier support.
223  */
224
225 static enum stf_barrier_type stf_enabled_flush_types;
226 static bool no_stf_barrier;
227 bool stf_barrier;
228
229 static int __init handle_no_stf_barrier(char *p)
230 {
231         pr_info("stf-barrier: disabled on command line.");
232         no_stf_barrier = true;
233         return 0;
234 }
235
236 early_param("no_stf_barrier", handle_no_stf_barrier);
237
238 /* This is the generic flag used by other architectures */
239 static int __init handle_ssbd(char *p)
240 {
241         if (!p || strncmp(p, "auto", 5) == 0 || strncmp(p, "on", 2) == 0 ) {
242                 /* Until firmware tells us, we have the barrier with auto */
243                 return 0;
244         } else if (strncmp(p, "off", 3) == 0) {
245                 handle_no_stf_barrier(NULL);
246                 return 0;
247         } else
248                 return 1;
249
250         return 0;
251 }
252 early_param("spec_store_bypass_disable", handle_ssbd);
253
254 /* This is the generic flag used by other architectures */
255 static int __init handle_no_ssbd(char *p)
256 {
257         handle_no_stf_barrier(NULL);
258         return 0;
259 }
260 early_param("nospec_store_bypass_disable", handle_no_ssbd);
261
262 static void stf_barrier_enable(bool enable)
263 {
264         if (enable)
265                 do_stf_barrier_fixups(stf_enabled_flush_types);
266         else
267                 do_stf_barrier_fixups(STF_BARRIER_NONE);
268
269         stf_barrier = enable;
270 }
271
272 void setup_stf_barrier(void)
273 {
274         enum stf_barrier_type type;
275         bool enable, hv;
276
277         hv = cpu_has_feature(CPU_FTR_HVMODE);
278
279         /* Default to fallback in case fw-features are not available */
280         if (cpu_has_feature(CPU_FTR_ARCH_300))
281                 type = STF_BARRIER_EIEIO;
282         else if (cpu_has_feature(CPU_FTR_ARCH_207S))
283                 type = STF_BARRIER_SYNC_ORI;
284         else if (cpu_has_feature(CPU_FTR_ARCH_206))
285                 type = STF_BARRIER_FALLBACK;
286         else
287                 type = STF_BARRIER_NONE;
288
289         enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
290                 (security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR) ||
291                  (security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) && hv));
292
293         if (type == STF_BARRIER_FALLBACK) {
294                 pr_info("stf-barrier: fallback barrier available\n");
295         } else if (type == STF_BARRIER_SYNC_ORI) {
296                 pr_info("stf-barrier: hwsync barrier available\n");
297         } else if (type == STF_BARRIER_EIEIO) {
298                 pr_info("stf-barrier: eieio barrier available\n");
299         }
300
301         stf_enabled_flush_types = type;
302
303         if (!no_stf_barrier && !cpu_mitigations_off())
304                 stf_barrier_enable(enable);
305 }
306
307 ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
308 {
309         if (stf_barrier && stf_enabled_flush_types != STF_BARRIER_NONE) {
310                 const char *type;
311                 switch (stf_enabled_flush_types) {
312                 case STF_BARRIER_EIEIO:
313                         type = "eieio";
314                         break;
315                 case STF_BARRIER_SYNC_ORI:
316                         type = "hwsync";
317                         break;
318                 case STF_BARRIER_FALLBACK:
319                         type = "fallback";
320                         break;
321                 default:
322                         type = "unknown";
323                 }
324                 return sprintf(buf, "Mitigation: Kernel entry/exit barrier (%s)\n", type);
325         }
326
327         if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
328             !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
329                 return sprintf(buf, "Not affected\n");
330
331         return sprintf(buf, "Vulnerable\n");
332 }
333
334 #ifdef CONFIG_DEBUG_FS
335 static int stf_barrier_set(void *data, u64 val)
336 {
337         bool enable;
338
339         if (val == 1)
340                 enable = true;
341         else if (val == 0)
342                 enable = false;
343         else
344                 return -EINVAL;
345
346         /* Only do anything if we're changing state */
347         if (enable != stf_barrier)
348                 stf_barrier_enable(enable);
349
350         return 0;
351 }
352
353 static int stf_barrier_get(void *data, u64 *val)
354 {
355         *val = stf_barrier ? 1 : 0;
356         return 0;
357 }
358
359 DEFINE_SIMPLE_ATTRIBUTE(fops_stf_barrier, stf_barrier_get, stf_barrier_set, "%llu\n");
360
361 static __init int stf_barrier_debugfs_init(void)
362 {
363         debugfs_create_file("stf_barrier", 0600, powerpc_debugfs_root, NULL, &fops_stf_barrier);
364         return 0;
365 }
366 device_initcall(stf_barrier_debugfs_init);
367 #endif /* CONFIG_DEBUG_FS */
368
369 static void toggle_count_cache_flush(bool enable)
370 {
371         if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) {
372                 patch_instruction_site(&patch__call_flush_count_cache, PPC_INST_NOP);
373                 count_cache_flush_type = COUNT_CACHE_FLUSH_NONE;
374                 pr_info("count-cache-flush: software flush disabled.\n");
375                 return;
376         }
377
378         patch_branch_site(&patch__call_flush_count_cache,
379                           (u64)&flush_count_cache, BRANCH_SET_LINK);
380
381         if (!security_ftr_enabled(SEC_FTR_BCCTR_FLUSH_ASSIST)) {
382                 count_cache_flush_type = COUNT_CACHE_FLUSH_SW;
383                 pr_info("count-cache-flush: full software flush sequence enabled.\n");
384                 return;
385         }
386
387         patch_instruction_site(&patch__flush_count_cache_return, PPC_INST_BLR);
388         count_cache_flush_type = COUNT_CACHE_FLUSH_HW;
389         pr_info("count-cache-flush: hardware assisted flush sequence enabled\n");
390 }
391
392 void setup_count_cache_flush(void)
393 {
394         toggle_count_cache_flush(true);
395 }
396
397 #ifdef CONFIG_DEBUG_FS
398 static int count_cache_flush_set(void *data, u64 val)
399 {
400         bool enable;
401
402         if (val == 1)
403                 enable = true;
404         else if (val == 0)
405                 enable = false;
406         else
407                 return -EINVAL;
408
409         toggle_count_cache_flush(enable);
410
411         return 0;
412 }
413
414 static int count_cache_flush_get(void *data, u64 *val)
415 {
416         if (count_cache_flush_type == COUNT_CACHE_FLUSH_NONE)
417                 *val = 0;
418         else
419                 *val = 1;
420
421         return 0;
422 }
423
424 DEFINE_SIMPLE_ATTRIBUTE(fops_count_cache_flush, count_cache_flush_get,
425                         count_cache_flush_set, "%llu\n");
426
427 static __init int count_cache_flush_debugfs_init(void)
428 {
429         debugfs_create_file("count_cache_flush", 0600, powerpc_debugfs_root,
430                             NULL, &fops_count_cache_flush);
431         return 0;
432 }
433 device_initcall(count_cache_flush_debugfs_init);
434 #endif /* CONFIG_DEBUG_FS */
435 #endif /* CONFIG_PPC_BOOK3S_64 */