MDEV-18025: Improve test case and consistency checks

Write a test case that computes valid crc32 checksums for
an encrypted page, but zeroes out the payload area, so
that the checksum after decryption fails.

xb_fil_cur_read(): Validate the page number before trying
any checksum calculation or decrypting or decompression.
Also, skip zero-filled pages. For page_compressed pages,
ensure that the FIL_PAGE_TYPE was changed. Also, reject
FIL_PAGE_PAGE_COMPRESSED_ENCRYPTED if no decryption was attempted.

extra/mariabackup/fil_cur.cc

@@ -353,6 +353,27 @@ xb_fil_cur_read(
 		    && page_no >= FSP_EXTENT_SIZE
 		    && page_no < FSP_EXTENT_SIZE * 3) {
 			/* We ignore the doublewrite buffer pages */
+                } else if (mach_read_from_4(page + FIL_PAGE_OFFSET) != page_no
+			   && space->id != TRX_SYS_SPACE) {
+			/* On pages that are not all zero, the
+			page number must match.
+
+			There may be a mismatch on tablespace ID,
+			because files may be renamed during backup.
+			We disable the page number check
+			on the system tablespace, because it may consist
+			of multiple files, and here we count the pages
+			from the start of each file.)
+
+			The first 38 and last 8 bytes are never encrypted. */
+			const ulint* p = reinterpret_cast<ulint*>(page);
+			const ulint* const end = reinterpret_cast<ulint*>(
+				page + cursor->page_size);
+			do {
+				if (*p++) {
+					goto corrupted;
+				}
+			} while (p != end);
 		} else if (mach_read_from_4(
 				   page
 				   + FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION)
@@ -361,9 +382,6 @@ xb_fil_cur_read(
 			   != CRYPT_SCHEME_UNENCRYPTED
 			   && fil_space_verify_crypt_checksum(
 				   page, cursor->zip_size)) {
-			ut_ad(mach_read_from_4(page + FIL_PAGE_SPACE_ID)
-			      == space->id);
-
 			bool decrypted = false;
 
 			memcpy(tmp_page, page, cursor->page_size);
@@ -381,21 +399,25 @@ xb_fil_cur_read(
 				true, tmp_page, cursor->zip_size, space)) {
 				goto corrupted;
 			}
-
 		} else if (page_type == FIL_PAGE_PAGE_COMPRESSED) {
 			memcpy(tmp_page, page, cursor->page_size);
 page_decomp:
 			ulint decomp = fil_page_decompress(tmp_frame, tmp_page);
+			page_type = mach_read_from_2(tmp_page + FIL_PAGE_TYPE);
 
 			if (!decomp
 			    || (decomp != srv_page_size && cursor->zip_size)
-			    || buf_page_is_corrupted(
-					true, tmp_page, cursor->zip_size, space)) {
+			    || page_type == FIL_PAGE_PAGE_COMPRESSED
+			    || page_type == FIL_PAGE_PAGE_COMPRESSED_ENCRYPTED
+			    || buf_page_is_corrupted(true, tmp_page,
+						     cursor->zip_size,
+						     space)) {
 				goto corrupted;
 			}
 
-		} else if (buf_page_is_corrupted(true, page, cursor->zip_size,
-						 space)) {
+		} else if (page_type == FIL_PAGE_PAGE_COMPRESSED_ENCRYPTED
+			   || buf_page_is_corrupted(true, page,
+						    cursor->zip_size, space)) {
 corrupted:
 			retry_count--;
 

mysql-test/suite/innodb/include/crc32.pl

+# The following is Public Domain / Creative Commons CC0 from
+# http://billauer.co.il/blog/2011/05/perl-crc32-crc-xs-module/
+
+sub mycrc32 {
+ my ($input, $init_value, $polynomial) = @_;
+
+ $init_value = 0 unless (defined $init_value);
+ $polynomial = 0xedb88320 unless (defined $polynomial);
+
+ my @lookup_table;
+
+ for (my $i=0; $i<256; $i++) {
+   my $x = $i;
+   for (my $j=0; $j<8; $j++) {
+     if ($x & 1) {
+       $x = ($x >> 1) ^ $polynomial;
+     } else {
+       $x = $x >> 1;
+     }
+   }
+   push @lookup_table, $x;
+ }
+
+ my $crc = $init_value ^ 0xffffffff;
+
+ foreach my $x (unpack ('C*', $input)) {
+   $crc = (($crc >> 8) & 0xffffff) ^ $lookup_table[ ($crc ^ $x) & 0xff ];
+ }
+
+ $crc = $crc ^ 0xffffffff;
+
+ return $crc;
+}

mysql-test/suite/mariabackup/encrypted_page_corruption.result

-call mtr.add_suppression("\\[ERROR\\] InnoDB: The page .* in file .* cannot be decrypted.");
+call mtr.add_suppression("\\[ERROR\\] InnoDB: The page \\[page id: space=[1-9][0-9]*, page number=3\\] in file '.*test.t1\\.ibd' cannot be decrypted.");
 CREATE TABLE t1(c VARCHAR(128)) ENGINE INNODB, encrypted=yes;
 insert into t1 select repeat('a',100);
 # Corrupt the table

mysql-test/suite/mariabackup/encrypted_page_corruption.test

 --source include/have_file_key_management.inc
+--source include/innodb_page_size.inc
 
-call mtr.add_suppression("\\[ERROR\\] InnoDB: The page .* in file .* cannot be decrypted.");
+perl;
+open(OUT, ">$ENV{MYSQLTEST_VARDIR}/log/check.txt") || die;
+print OUT "--skip innodb_checksum_algorithm=crc32 needs little-endian\n"
+unless unpack("L","macs")==unpack("N","scam");
+close(OUT);
+EOF
+
+--source $MYSQLTEST_VARDIR/log/check.txt
+--remove_file $MYSQLTEST_VARDIR/log/check.txt
+
+call mtr.add_suppression("\\[ERROR\\] InnoDB: The page \\[page id: space=[1-9][0-9]*, page number=3\\] in file '.*test.t1\\.ibd' cannot be decrypted.");
 CREATE TABLE t1(c VARCHAR(128)) ENGINE INNODB, encrypted=yes;
 insert into t1 select repeat('a',100);
 
-let $MYSQLD_DATADIR=`select @@datadir`;
-let t1_IBD = $MYSQLD_DATADIR/test/t1.ibd;
+let MYSQLD_DATADIR=`select @@datadir`;
+let INNODB_PAGE_SIZE=`select @@innodb_page_size`;
 
 --source include/shutdown_mysqld.inc
 
@@ -15,17 +26,29 @@ perl;
 use strict;
 use warnings;
 use Fcntl qw(:DEFAULT :seek);
+do "$ENV{MTR_SUITE_DIR}/../innodb/include/crc32.pl";
+
+my $page_size = $ENV{INNODB_PAGE_SIZE};
 
-my $ibd_file = $ENV{'t1_IBD'};
+sysopen IBD_FILE, "$ENV{MYSQLD_DATADIR}/test/t1.ibd", O_RDWR
+|| die "Cannot open t1.ibd\n";
+sysread(IBD_FILE, $_, 38) || die "Cannot read t1.ibd\n";
+my $space = unpack("x[34]N", $_);
+sysseek(IBD_FILE, $page_size * 3, SEEK_SET) || die "Cannot seek t1.ibd\n";
 
-my $chunk;
-my $len;
+my $head = pack("Nx[18]", 3); # better to have a valid page number
+my $body = chr(0) x ($page_size - 38 - 8);
 
-sysopen IBD_FILE, $ibd_file, O_RDWR || die "Unable to open $ibd_file";
-sysseek IBD_FILE, 16384 * 3, SEEK_CUR;
-$chunk = '\xAA\xAA\xAA\xAA';
-syswrite IBD_FILE, $chunk, 4;
+# Calculate innodb_checksum_algorithm=crc32 for the unencrypted page.
+# The following bytes are excluded:
+# bytes 0..3 (the checksum is stored there)
+# bytes 26..37 (encryption key version, post-encryption checksum, tablespace id)
+# bytes $page_size-8..$page_size-1 (checksum, LSB of FIL_PAGE_LSN)
+my $polynomial = 0x82f63b78; # CRC-32C
+my $ck = mycrc32($head, 0, $polynomial) ^ mycrc32($body, 0, $polynomial);
 
+my $page= pack("N",$ck).$head.pack("NNN",1,$ck,$space).$body.pack("Nx[4]",$ck);
+die unless syswrite(IBD_FILE, $page, $page_size) == $page_size;
 close IBD_FILE;
 EOF