Adding upstream version 1.47.0.upstream/1.47.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 458 insertions, 0 deletions

diff --git a/e2fsck/encrypted_files.c b/e2fsck/encrypted_files.c
new file mode 100644
index 0000000..16be2d6
--- /dev/null
+++ b/e2fsck/encrypted_files.c
@@ -0,0 +1,458 @@
+/*
+ * encrypted_files.c --- save information about encrypted files
+ *
+ * Copyright 2019 Google LLC
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+/*
+ * e2fsck pass 1 (inode table scan) creates a map from inode number to
+ * encryption policy for all encrypted inodes.  But it's optimized so that the
+ * full xattrs aren't saved but rather only 32-bit "policy IDs", since usually
+ * many inodes share the same encryption policy.  This requires also maintaining
+ * a second map, from policy to policy ID.  See add_encrypted_file().
+ *
+ * We also use run-length encoding to save memory when many adjacent inodes
+ * share the same encryption policy, which is often the case too.
+ *
+ * e2fsck pass 2 (directory structure check) uses the inode => policy ID map to
+ * verify that all regular files, directories, and symlinks in encrypted
+ * directories use the directory's encryption policy.
+ */
+
+#include "config.h"
+
+#include "e2fsck.h"
+#include "problem.h"
+#include "ext2fs/rbtree.h"
+
+#define FSCRYPT_KEY_DESCRIPTOR_SIZE	8
+#define FSCRYPT_KEY_IDENTIFIER_SIZE	16
+#define FS_KEY_DERIVATION_NONCE_SIZE	16
+
+struct fscrypt_context_v1 {
+	__u8 version;
+	__u8 contents_encryption_mode;
+	__u8 filenames_encryption_mode;
+	__u8 flags;
+	__u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
+	__u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
+};
+
+struct fscrypt_context_v2 {
+	__u8 version;
+	__u8 contents_encryption_mode;
+	__u8 filenames_encryption_mode;
+	__u8 flags;
+	__u8 __reserved[4];
+	__u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
+	__u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
+};
+
+/* On-disk format of encryption xattr */
+union fscrypt_context {
+	__u8 version;
+	struct fscrypt_context_v1 v1;
+	struct fscrypt_context_v2 v2;
+};
+
+struct fscrypt_policy_v1 {
+	__u8 version;
+	__u8 contents_encryption_mode;
+	__u8 filenames_encryption_mode;
+	__u8 flags;
+	__u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
+};
+
+struct fscrypt_policy_v2 {
+	__u8 version;
+	__u8 contents_encryption_mode;
+	__u8 filenames_encryption_mode;
+	__u8 flags;
+	__u8 __reserved[4];
+	__u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
+};
+
+/* The encryption "policy" is the fscrypt_context excluding the nonce. */
+union fscrypt_policy {
+	__u8 version;
+	struct fscrypt_policy_v1 v1;
+	struct fscrypt_policy_v2 v2;
+};
+
+/* A range of inodes which share the same encryption policy */
+struct encrypted_file_range {
+	ext2_ino_t		first_ino;
+	ext2_ino_t		last_ino;
+	__u32			policy_id;
+};
+
+/* Information about the encrypted files which have been seen so far */
+struct encrypted_file_info {
+	/*
+	 * Map from inode number to encryption policy ID, implemented as a
+	 * sorted array of inode ranges, each of which shares the same policy.
+	 * Inodes are added in order of increasing inode number.
+	 *
+	 * Freed after pass 2.
+	 */
+	struct encrypted_file_range	*file_ranges;
+	size_t				file_ranges_count;
+	size_t				file_ranges_capacity;
+
+	/*
+	 * Map from encryption policy to encryption policy ID, for the unique
+	 * encryption policies that have been seen so far.  next_policy_id is
+	 * the next available ID, starting at 0.
+	 *
+	 * Freed after pass 1.
+	 */
+	struct rb_root		policies;
+	__u32			next_policy_id;
+};
+
+/* Entry in encrypted_file_info::policies */
+struct policy_map_entry {
+	union fscrypt_policy	policy;
+	__u32			policy_id;
+	struct rb_node		node;
+};
+
+static int cmp_fscrypt_policies(e2fsck_t ctx, const union fscrypt_policy *a,
+				const union fscrypt_policy *b)
+{
+	if (a->version != b->version)
+		return (int)a->version - (int)b->version;
+
+	switch (a->version) {
+	case 1:
+		return memcmp(a, b, sizeof(a->v1));
+	case 2:
+		return memcmp(a, b, sizeof(a->v2));
+	}
+	fatal_error(ctx, "Unhandled encryption policy version");
+	return 0;
+}
+
+/* Read an inode's encryption xattr. */
+static errcode_t read_encryption_xattr(e2fsck_t ctx, ext2_ino_t ino,
+				       void **value, size_t *value_len)
+{
+	struct ext2_xattr_handle *h;
+	errcode_t retval;
+
+	retval = ext2fs_xattrs_open(ctx->fs, ino, &h);
+	if (retval)
+		return retval;
+
+	retval = ext2fs_xattrs_read(h);
+	if (retval == 0)
+		retval = ext2fs_xattr_get(h, "c", value, value_len);
+
+	ext2fs_xattrs_close(&h);
+	return retval;
+}
+
+/*
+ * Convert an fscrypt_context to an fscrypt_policy.  Returns 0,
+ * CORRUPT_ENCRYPTION_POLICY, or UNRECOGNIZED_ENCRYPTION_POLICY.
+ */
+static __u32 fscrypt_context_to_policy(const void *xattr, size_t xattr_size,
+				       union fscrypt_policy *policy_u)
+{
+	const union fscrypt_context *ctx_u = xattr;
+
+	if (xattr_size < 1)
+		return CORRUPT_ENCRYPTION_POLICY;
+	switch (ctx_u->version) {
+	case 0:
+		return CORRUPT_ENCRYPTION_POLICY;
+	case 1: {
+		struct fscrypt_policy_v1 *policy = &policy_u->v1;
+		const struct fscrypt_context_v1 *ctx = &ctx_u->v1;
+
+		if (xattr_size != sizeof(*ctx))
+			return CORRUPT_ENCRYPTION_POLICY;
+		policy->version = ctx->version;
+		policy->contents_encryption_mode =
+			ctx->contents_encryption_mode;
+		policy->filenames_encryption_mode =
+			ctx->filenames_encryption_mode;
+		policy->flags = ctx->flags;
+		memcpy(policy->master_key_descriptor,
+		       ctx->master_key_descriptor,
+		       sizeof(policy->master_key_descriptor));
+		return 0;
+	}
+	case 2: {
+		struct fscrypt_policy_v2 *policy = &policy_u->v2;
+		const struct fscrypt_context_v2 *ctx = &ctx_u->v2;
+
+		if (xattr_size != sizeof(*ctx))
+			return CORRUPT_ENCRYPTION_POLICY;
+		policy->version = ctx->version;
+		policy->contents_encryption_mode =
+			ctx->contents_encryption_mode;
+		policy->filenames_encryption_mode =
+			ctx->filenames_encryption_mode;
+		policy->flags = ctx->flags;
+		memcpy(policy->__reserved, ctx->__reserved,
+		       sizeof(policy->__reserved));
+		memcpy(policy->master_key_identifier,
+		       ctx->master_key_identifier,
+		       sizeof(policy->master_key_identifier));
+		return 0;
+	}
+	}
+	return UNRECOGNIZED_ENCRYPTION_POLICY;
+}
+
+/*
+ * Read an inode's encryption xattr and get/allocate its encryption policy ID,
+ * or alternatively use one of the special IDs NO_ENCRYPTION_POLICY,
+ * CORRUPT_ENCRYPTION_POLICY, or UNRECOGNIZED_ENCRYPTION_POLICY.
+ *
+ * Returns nonzero only if out of memory.
+ */
+static errcode_t get_encryption_policy_id(e2fsck_t ctx, ext2_ino_t ino,
+					  __u32 *policy_id_ret)
+{
+	struct encrypted_file_info *info = ctx->encrypted_files;
+	struct rb_node **new = &info->policies.rb_node;
+	struct rb_node *parent = NULL;
+	void *xattr;
+	size_t xattr_size;
+	union fscrypt_policy policy;
+	__u32 policy_id;
+	struct policy_map_entry *entry;
+	errcode_t retval;
+
+	retval = read_encryption_xattr(ctx, ino, &xattr, &xattr_size);
+	if (retval == EXT2_ET_NO_MEMORY)
+		return retval;
+	if (retval) {
+		*policy_id_ret = NO_ENCRYPTION_POLICY;
+		return 0;
+	}
+
+	/* Translate the xattr to an fscrypt_policy, if possible. */
+	policy_id = fscrypt_context_to_policy(xattr, xattr_size, &policy);
+	ext2fs_free_mem(&xattr);
+	if (policy_id != 0)
+		goto out;
+
+	/* Check if the policy was already seen. */
+	while (*new) {
+		int res;
+
+		parent = *new;
+		entry = ext2fs_rb_entry(parent, struct policy_map_entry, node);
+		res = cmp_fscrypt_policies(ctx, &policy, &entry->policy);
+		if (res < 0) {
+			new = &parent->rb_left;
+		} else if (res > 0) {
+			new = &parent->rb_right;
+		} else {
+			/* Policy already seen.  Use existing ID. */
+			policy_id = entry->policy_id;
+			goto out;
+		}
+	}
+
+	/* First time seeing this policy.  Allocate a new policy ID. */
+	retval = ext2fs_get_mem(sizeof(*entry), &entry);
+	if (retval)
+		goto out;
+	policy_id = info->next_policy_id++;
+	entry->policy_id = policy_id;
+	entry->policy = policy;
+	ext2fs_rb_link_node(&entry->node, parent, new);
+	ext2fs_rb_insert_color(&entry->node, &info->policies);
+out:
+	*policy_id_ret = policy_id;
+	return retval;
+}
+
+static int handle_nomem(e2fsck_t ctx, struct problem_context *pctx,
+			size_t size_needed)
+{
+	pctx->num = size_needed;
+	fix_problem(ctx, PR_1_ALLOCATE_ENCRYPTED_INODE_LIST, pctx);
+	/* Should never get here */
+	ctx->flags |= E2F_FLAG_ABORT;
+	return 0;
+}
+
+static int append_ino_and_policy_id(e2fsck_t ctx, struct problem_context *pctx,
+				    ext2_ino_t ino, __u32 policy_id)
+{
+	struct encrypted_file_info *info = ctx->encrypted_files;
+	struct encrypted_file_range *range;
+
+	/* See if we can just extend the last range. */
+	if (info->file_ranges_count > 0) {
+		range = &info->file_ranges[info->file_ranges_count - 1];
+
+		if (ino <= range->last_ino) {
+			/* Should never get here */
+			fatal_error(ctx,
+				    "Encrypted inodes processed out of order");
+		}
+
+		if (ino == range->last_ino + 1 &&
+		    policy_id == range->policy_id) {
+			range->last_ino++;
+			return 0;
+		}
+	}
+	/* Nope, a new range is needed. */
+
+	if (info->file_ranges_count == info->file_ranges_capacity) {
+		/* Double the capacity by default. */
+		size_t new_capacity = info->file_ranges_capacity * 2;
+
+		/* ... but go from 0 to 128 right away. */
+		if (new_capacity < 128)
+			new_capacity = 128;
+
+		/* We won't need more than the filesystem's inode count. */
+		if (new_capacity > ctx->fs->super->s_inodes_count)
+			new_capacity = ctx->fs->super->s_inodes_count;
+
+		/* To be safe, ensure the capacity really increases. */
+		if (new_capacity < info->file_ranges_capacity + 1)
+			new_capacity = info->file_ranges_capacity + 1;
+
+		if (ext2fs_resize_mem(info->file_ranges_capacity *
+					sizeof(*range),
+				      new_capacity * sizeof(*range),
+				      &info->file_ranges) != 0)
+			return handle_nomem(ctx, pctx,
+					    new_capacity * sizeof(*range));
+
+		info->file_ranges_capacity = new_capacity;
+	}
+	range = &info->file_ranges[info->file_ranges_count++];
+	range->first_ino = ino;
+	range->last_ino = ino;
+	range->policy_id = policy_id;
+	return 0;
+}
+
+/*
+ * Handle an inode that has EXT4_ENCRYPT_FL set during pass 1.  Normally this
+ * just finds the unique ID that identifies the inode's encryption policy
+ * (allocating a new ID if needed), and adds the inode number and its policy ID
+ * to the encrypted_file_info so that it's available in pass 2.
+ *
+ * But this also handles:
+ * - If the inode doesn't have an encryption xattr at all, offer to clear the
+ *   encrypt flag.
+ * - If the encryption xattr is clearly corrupt, tell the caller that the whole
+ *   inode should be cleared.
+ * - To be future-proof: if the encryption xattr has an unrecognized version
+ *   number, it *might* be valid, so we don't consider it invalid.  But we can't
+ *   do much with it, so give all such policies the same ID,
+ *   UNRECOGNIZED_ENCRYPTION_POLICY.
+ *
+ * Returns -1 if the inode should be cleared, otherwise 0.
+ */
+int add_encrypted_file(e2fsck_t ctx, struct problem_context *pctx)
+{
+	struct encrypted_file_info *info = ctx->encrypted_files;
+	ext2_ino_t ino = pctx->ino;
+	__u32 policy_id;
+
+	/* Allocate the encrypted_file_info if needed. */
+	if (info == NULL) {
+		if (ext2fs_get_memzero(sizeof(*info), &info) != 0)
+			return handle_nomem(ctx, pctx, sizeof(*info));
+		ctx->encrypted_files = info;
+	}
+
+	/* Get a unique ID for this inode's encryption policy. */
+	if (get_encryption_policy_id(ctx, ino, &policy_id) != 0)
+		return handle_nomem(ctx, pctx, 0 /* unknown size */);
+	if (policy_id == NO_ENCRYPTION_POLICY) {
+		if (fix_problem(ctx, PR_1_MISSING_ENCRYPTION_XATTR, pctx)) {
+			pctx->inode->i_flags &= ~EXT4_ENCRYPT_FL;
+			e2fsck_write_inode(ctx, ino, pctx->inode, "pass1");
+		}
+		return 0;
+	} else if (policy_id == CORRUPT_ENCRYPTION_POLICY) {
+		if (fix_problem(ctx, PR_1_CORRUPT_ENCRYPTION_XATTR, pctx))
+			return -1;
+		return 0;
+	}
+
+	/* Store this ino => policy_id mapping in the encrypted_file_info. */
+	return append_ino_and_policy_id(ctx, pctx, ino, policy_id);
+}
+
+/*
+ * Find the ID of an inode's encryption policy, using the information saved
+ * earlier.
+ *
+ * If the inode is encrypted, returns the policy ID or
+ * UNRECOGNIZED_ENCRYPTION_POLICY.  Else, returns NO_ENCRYPTION_POLICY.
+ */
+__u32 find_encryption_policy(e2fsck_t ctx, ext2_ino_t ino)
+{
+	const struct encrypted_file_info *info = ctx->encrypted_files;
+	size_t l, r;
+
+	if (info == NULL)
+		return NO_ENCRYPTION_POLICY;
+	l = 0;
+	r = info->file_ranges_count;
+	while (l < r) {
+		size_t m = l + (r - l) / 2;
+		const struct encrypted_file_range *range =
+			&info->file_ranges[m];
+
+		if (ino < range->first_ino)
+			r = m;
+		else if (ino > range->last_ino)
+			l = m + 1;
+		else
+			return range->policy_id;
+	}
+	return NO_ENCRYPTION_POLICY;
+}
+
+/* Destroy ctx->encrypted_files->policies */
+void destroy_encryption_policy_map(e2fsck_t ctx)
+{
+	struct encrypted_file_info *info = ctx->encrypted_files;
+
+	if (info) {
+		struct rb_root *policies = &info->policies;
+
+		while (!ext2fs_rb_empty_root(policies)) {
+			struct policy_map_entry *entry;
+
+			entry = ext2fs_rb_entry(policies->rb_node,
+						struct policy_map_entry, node);
+			ext2fs_rb_erase(&entry->node, policies);
+			ext2fs_free_mem(&entry);
+		}
+		info->next_policy_id = 0;
+	}
+}
+
+/* Destroy ctx->encrypted_files */
+void destroy_encrypted_file_info(e2fsck_t ctx)
+{
+	struct encrypted_file_info *info = ctx->encrypted_files;
+
+	if (info) {
+		destroy_encryption_policy_map(ctx);
+		ext2fs_free_mem(&info->file_ranges);
+		ext2fs_free_mem(&info);
+		ctx->encrypted_files = NULL;
+	}
+}