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2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc 
 kernel/fs/crypto/policy.c
....@@ -32,6 +32,14 @@
3232 	return !memcmp(policy1, policy2, fscrypt_policy_size(policy1));
3333 }
3434 
35
+static const union fscrypt_policy *
36
+fscrypt_get_dummy_policy(struct super_block *sb)
37
+{
38
+	if (!sb->s_cop->get_dummy_policy)
39
+		return NULL;
40
+	return sb->s_cop->get_dummy_policy(sb);
41
+}
42
+
3543 static bool fscrypt_valid_enc_modes(u32 contents_mode, u32 filenames_mode)
3644 {
3745 	if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
....@@ -167,7 +175,10 @@
167175 		return false;
168176 	}
169177 
170
-	if (policy->flags & ~FSCRYPT_POLICY_FLAGS_VALID) {
178
+	if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK |
179
+			      FSCRYPT_POLICY_FLAG_DIRECT_KEY |
180
+			      FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 |
181
+			      FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) {
171182 		fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)",
172183 			     policy->flags);
173184 		return false;
....@@ -236,18 +247,19 @@
236247 }
237248 
238249 /**
239
- * fscrypt_new_context_from_policy() - create a new fscrypt_context from
240
- *				       an fscrypt_policy
250
+ * fscrypt_new_context() - create a new fscrypt_context
241251  * @ctx_u: output context
242252  * @policy_u: input policy
253
+ * @nonce: nonce to use
243254  *
244255  * Create an fscrypt_context for an inode that is being assigned the given
245
- * encryption policy.  A new nonce is randomly generated.
256
+ * encryption policy.  @nonce must be a new random nonce.
246257  *
247258  * Return: the size of the new context in bytes.
248259  */
249
-static int fscrypt_new_context_from_policy(union fscrypt_context *ctx_u,
250
-					   const union fscrypt_policy *policy_u)
260
+static int fscrypt_new_context(union fscrypt_context *ctx_u,
261
+			       const union fscrypt_policy *policy_u,
262
+			       const u8 nonce[FSCRYPT_FILE_NONCE_SIZE])
251263 {
252264 	memset(ctx_u, 0, sizeof(*ctx_u));
253265 
....@@ -265,7 +277,7 @@
265277 		memcpy(ctx->master_key_descriptor,
266278 		       policy->master_key_descriptor,
267279 		       sizeof(ctx->master_key_descriptor));
268
-		get_random_bytes(ctx->nonce, sizeof(ctx->nonce));
280
+		memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);
269281 		return sizeof(*ctx);
270282 	}
271283 	case FSCRYPT_POLICY_V2: {
....@@ -281,7 +293,7 @@
281293 		memcpy(ctx->master_key_identifier,
282294 		       policy->master_key_identifier,
283295 		       sizeof(ctx->master_key_identifier));
284
-		get_random_bytes(ctx->nonce, sizeof(ctx->nonce));
296
+		memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);
285297 		return sizeof(*ctx);
286298 	}
287299 	}
....@@ -357,7 +369,7 @@
357369 	union fscrypt_context ctx;
358370 	int ret;
359371 
360
-	ci = READ_ONCE(inode->i_crypt_info);
372
+	ci = fscrypt_get_info(inode);
361373 	if (ci) {
362374 		/* key available, use the cached policy */
363375 		*policy = ci->ci_policy;
....@@ -377,6 +389,7 @@
377389 static int set_encryption_policy(struct inode *inode,
378390 				 const union fscrypt_policy *policy)
379391 {
392
+	u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
380393 	union fscrypt_context ctx;
381394 	int ctxsize;
382395 	int err;
....@@ -414,7 +427,8 @@
414427 		return -EINVAL;
415428 	}
416429 
417
-	ctxsize = fscrypt_new_context_from_policy(&ctx, policy);
430
+	get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE);
431
+	ctxsize = fscrypt_new_context(&ctx, policy, nonce);
418432 
419433 	return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, NULL);
420434 }
....@@ -548,7 +562,7 @@
548562 	if (!fscrypt_context_is_valid(&ctx, ret))
549563 		return -EINVAL;
550564 	if (copy_to_user(arg, fscrypt_context_nonce(&ctx),
551
-			 FS_KEY_DERIVATION_NONCE_SIZE))
565
+			 FSCRYPT_FILE_NONCE_SIZE))
552566 		return -EFAULT;
553567 	return 0;
554568 }
....@@ -576,7 +590,7 @@
576590 int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
577591 {
578592 	union fscrypt_policy parent_policy, child_policy;
579
-	int err;
593
+	int err, err1, err2;
580594 
581595 	/* No restrictions on file types which are never encrypted */
582596 	if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) &&
....@@ -606,105 +620,120 @@
606620 	 * In any case, if an unexpected error occurs, fall back to "forbidden".
607621 	 */
608622 
609
-	err = fscrypt_get_encryption_info(parent);
623
+	err = fscrypt_get_encryption_info(parent, true);
610624 	if (err)
611625 		return 0;
612
-	err = fscrypt_get_encryption_info(child);
626
+	err = fscrypt_get_encryption_info(child, true);
613627 	if (err)
614628 		return 0;
615629 
616
-	err = fscrypt_get_policy(parent, &parent_policy);
617
-	if (err)
618
-		return 0;
630
+	err1 = fscrypt_get_policy(parent, &parent_policy);
631
+	err2 = fscrypt_get_policy(child, &child_policy);
619632 
620
-	err = fscrypt_get_policy(child, &child_policy);
621
-	if (err)
633
+	/*
634
+	 * Allow the case where the parent and child both have an unrecognized
635
+	 * encryption policy, so that files with an unrecognized encryption
636
+	 * policy can be deleted.
637
+	 */
638
+	if (err1 == -EINVAL && err2 == -EINVAL)
639
+		return 1;
640
+
641
+	if (err1 || err2)
622642 		return 0;
623643 
624644 	return fscrypt_policies_equal(&parent_policy, &child_policy);
625645 }
626646 EXPORT_SYMBOL(fscrypt_has_permitted_context);
627647 
648
+/*
649
+ * Return the encryption policy that new files in the directory will inherit, or
650
+ * NULL if none, or an ERR_PTR() on error.  If the directory is encrypted, also
651
+ * ensure that its key is set up, so that the new filename can be encrypted.
652
+ */
653
+const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir)
654
+{
655
+	int err;
656
+
657
+	if (IS_ENCRYPTED(dir)) {
658
+		err = fscrypt_require_key(dir);
659
+		if (err)
660
+			return ERR_PTR(err);
661
+		return &dir->i_crypt_info->ci_policy;
662
+	}
663
+
664
+	return fscrypt_get_dummy_policy(dir->i_sb);
665
+}
666
+
628667 /**
629
- * fscrypt_inherit_context() - Sets a child context from its parent
630
- * @parent: Parent inode from which the context is inherited.
631
- * @child:  Child inode that inherits the context from @parent.
632
- * @fs_data:  private data given by FS.
633
- * @preload:  preload child i_crypt_info if true
668
+ * fscrypt_set_context() - Set the fscrypt context of a new inode
669
+ * @inode: a new inode
670
+ * @fs_data: private data given by FS and passed to ->set_context()
671
+ *
672
+ * This should be called after fscrypt_prepare_new_inode(), generally during a
673
+ * filesystem transaction.  Everything here must be %GFP_NOFS-safe.
634674  *
635675  * Return: 0 on success, -errno on failure
636676  */
637
-int fscrypt_inherit_context(struct inode *parent, struct inode *child,
638
-						void *fs_data, bool preload)
677
+int fscrypt_set_context(struct inode *inode, void *fs_data)
639678 {
679
+	struct fscrypt_info *ci = inode->i_crypt_info;
640680 	union fscrypt_context ctx;
641681 	int ctxsize;
642
-	struct fscrypt_info *ci;
643
-	int res;
644682 
645
-	res = fscrypt_get_encryption_info(parent);
646
-	if (res < 0)
647
-		return res;
648
-
649
-	ci = READ_ONCE(parent->i_crypt_info);
650
-	if (ci == NULL)
683
+	/* fscrypt_prepare_new_inode() should have set up the key already. */
684
+	if (WARN_ON_ONCE(!ci))
651685 		return -ENOKEY;
652686 
653
-	ctxsize = fscrypt_new_context_from_policy(&ctx, &ci->ci_policy);
654
-
655687 	BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE);
656
-	res = parent->i_sb->s_cop->set_context(child, &ctx, ctxsize, fs_data);
657
-	if (res)
658
-		return res;
659
-	return preload ? fscrypt_get_encryption_info(child): 0;
688
+	ctxsize = fscrypt_new_context(&ctx, &ci->ci_policy, ci->ci_nonce);
689
+
690
+	/*
691
+	 * This may be the first time the inode number is available, so do any
692
+	 * delayed key setup that requires the inode number.
693
+	 */
694
+	if (ci->ci_policy.version == FSCRYPT_POLICY_V2 &&
695
+	    (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32))
696
+		fscrypt_hash_inode_number(ci, ci->ci_master_key);
697
+
698
+	return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, fs_data);
660699 }
661
-EXPORT_SYMBOL(fscrypt_inherit_context);
700
+EXPORT_SYMBOL_GPL(fscrypt_set_context);
662701 
663702 /**
664703  * fscrypt_set_test_dummy_encryption() - handle '-o test_dummy_encryption'
665704  * @sb: the filesystem on which test_dummy_encryption is being specified
666
- * @arg: the argument to the test_dummy_encryption option.
667
- *	 If no argument was specified, then @arg->from == NULL.
668
- * @dummy_ctx: the filesystem's current dummy context (input/output, see below)
705
+ * @arg: the argument to the test_dummy_encryption option.  May be NULL.
706
+ * @dummy_policy: the filesystem's current dummy policy (input/output, see
707
+ *		  below)
669708  *
670709  * Handle the test_dummy_encryption mount option by creating a dummy encryption
671
- * context, saving it in @dummy_ctx, and adding the corresponding dummy
672
- * encryption key to the filesystem.  If the @dummy_ctx is already set, then
710
+ * policy, saving it in @dummy_policy, and adding the corresponding dummy
711
+ * encryption key to the filesystem.  If the @dummy_policy is already set, then
673712  * instead validate that it matches @arg.  Don't support changing it via
674713  * remount, as that is difficult to do safely.
675714  *
676
- * The reason we use an fscrypt_context rather than an fscrypt_policy is because
677
- * we mustn't generate a new nonce each time we access a dummy-encrypted
678
- * directory, as that would change the way filenames are encrypted.
679
- *
680
- * Return: 0 on success (dummy context set, or the same context is already set);
681
- *         -EEXIST if a different dummy context is already set;
715
+ * Return: 0 on success (dummy policy set, or the same policy is already set);
716
+ *         -EEXIST if a different dummy policy is already set;
682717  *         or another -errno value.
683718  */
684
-int fscrypt_set_test_dummy_encryption(struct super_block *sb,
685
-				      const substring_t *arg,
686
-				      struct fscrypt_dummy_context *dummy_ctx)
719
+int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg,
720
+				      struct fscrypt_dummy_policy *dummy_policy)
687721 {
688
-	const char *argstr = "v2";
689
-	const char *argstr_to_free = NULL;
690722 	struct fscrypt_key_specifier key_spec = { 0 };
691723 	int version;
692
-	union fscrypt_context *ctx = NULL;
724
+	union fscrypt_policy *policy = NULL;
693725 	int err;
694726 
695
-	if (arg->from) {
696
-		argstr = argstr_to_free = match_strdup(arg);
697
-		if (!argstr)
698
-			return -ENOMEM;
699
-	}
727
+	if (!arg)
728
+		arg = "v2";
700729 
701
-	if (!strcmp(argstr, "v1")) {
702
-		version = FSCRYPT_CONTEXT_V1;
730
+	if (!strcmp(arg, "v1")) {
731
+		version = FSCRYPT_POLICY_V1;
703732 		key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
704733 		memset(key_spec.u.descriptor, 0x42,
705734 		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
706
-	} else if (!strcmp(argstr, "v2")) {
707
-		version = FSCRYPT_CONTEXT_V2;
735
+	} else if (!strcmp(arg, "v2")) {
736
+		version = FSCRYPT_POLICY_V2;
708737 		key_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
709738 		/* key_spec.u.identifier gets filled in when adding the key */
710739 	} else {
....@@ -712,21 +741,8 @@
712741 		goto out;
713742 	}
714743 
715
-	if (dummy_ctx->ctx) {
716
-		/*
717
-		 * Note: if we ever make test_dummy_encryption support
718
-		 * specifying other encryption settings, such as the encryption
719
-		 * modes, we'll need to compare those settings here.
720
-		 */
721
-		if (dummy_ctx->ctx->version == version)
722
-			err = 0;
723
-		else
724
-			err = -EEXIST;
725
-		goto out;
726
-	}
727
-
728
-	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
729
-	if (!ctx) {
744
+	policy = kzalloc(sizeof(*policy), GFP_KERNEL);
745
+	if (!policy) {
730746 		err = -ENOMEM;
731747 		goto out;
732748 	}
....@@ -735,18 +751,18 @@
735751 	if (err)
736752 		goto out;
737753 
738
-	ctx->version = version;
739
-	switch (ctx->version) {
740
-	case FSCRYPT_CONTEXT_V1:
741
-		ctx->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
742
-		ctx->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
743
-		memcpy(ctx->v1.master_key_descriptor, key_spec.u.descriptor,
754
+	policy->version = version;
755
+	switch (policy->version) {
756
+	case FSCRYPT_POLICY_V1:
757
+		policy->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
758
+		policy->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
759
+		memcpy(policy->v1.master_key_descriptor, key_spec.u.descriptor,
744760 		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
745761 		break;
746
-	case FSCRYPT_CONTEXT_V2:
747
-		ctx->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
748
-		ctx->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
749
-		memcpy(ctx->v2.master_key_identifier, key_spec.u.identifier,
762
+	case FSCRYPT_POLICY_V2:
763
+		policy->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
764
+		policy->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
765
+		memcpy(policy->v2.master_key_identifier, key_spec.u.identifier,
750766 		       FSCRYPT_KEY_IDENTIFIER_SIZE);
751767 		break;
752768 	default:
....@@ -754,12 +770,19 @@
754770 		err = -EINVAL;
755771 		goto out;
756772 	}
757
-	dummy_ctx->ctx = ctx;
758
-	ctx = NULL;
773
+
774
+	if (dummy_policy->policy) {
775
+		if (fscrypt_policies_equal(policy, dummy_policy->policy))
776
+			err = 0;
777
+		else
778
+			err = -EEXIST;
779
+		goto out;
780
+	}
781
+	dummy_policy->policy = policy;
782
+	policy = NULL;
759783 	err = 0;
760784 out:
761
-	kfree(ctx);
762
-	kfree(argstr_to_free);
785
+	kfree(policy);
763786 	return err;
764787 }
765788 EXPORT_SYMBOL_GPL(fscrypt_set_test_dummy_encryption);
....@@ -776,10 +799,16 @@
776799 void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
777800 					struct super_block *sb)
778801 {
779
-	const union fscrypt_context *ctx = fscrypt_get_dummy_context(sb);
802
+	const union fscrypt_policy *policy = fscrypt_get_dummy_policy(sb);
803
+	int vers;
780804 
781
-	if (!ctx)
805
+	if (!policy)
782806 		return;
783
-	seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, ctx->version);
807
+
808
+	vers = policy->version;
809
+	if (vers == FSCRYPT_POLICY_V1) /* Handle numbering quirk */
810
+		vers = 1;
811
+
812
+	seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, vers);
784813 }
785814 EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption);