Remove dependence on zlib

Introduce env/env_api_crc32.c to support computation of CRC32
so that there is no longer a dependence on zlib.

Signed-off-by: Earl Chew <[email protected]>
[Jan: rebased, re-indented]
Signed-off-by: Jan Kiszka <[email protected]>

.github/workflows/coverity.yaml

@@ -33,7 +33,7 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install --no-install-recommends \
-              autoconf-archive gcc-multilib gnu-efi libz-dev libpci-dev check
+              autoconf-archive gcc-multilib gnu-efi libpci-dev check
       - name: Install Coverity
         run: |
           wget https://scan.coverity.com/download/cxx/linux64 \

.github/workflows/main.yaml

@@ -43,7 +43,7 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install --no-install-recommends \
-              autoconf-archive gcc-multilib gnu-efi libz-dev libpci-dev check \
+              autoconf-archive gcc-multilib gnu-efi libpci-dev check \
               bats libarchive-zip-perl
       - name: Install i386 dependencies
         if: ${{ matrix.target == 'i386' }}
@@ -52,7 +52,7 @@ jobs:
           sudo rm -f /etc/apt/sources.list.d/ubuntu-toolchain-r-ubuntu-test-jammy.list
           sudo apt-get update
           sudo apt-get install --no-install-recommends \
-              autoconf-archive gcc-multilib gnu-efi libz-dev:i386 \
+              autoconf-archive gcc-multilib gnu-efi \
               libpci-dev:i386 check:i386
       - name: Install arm64 dependencies
         if: ${{ matrix.target == 'arm64' }}
@@ -70,7 +70,7 @@ jobs:
           sudo apt-get update
           sudo apt-get install --no-install-recommends \
               autoconf-archive gcc-aarch64-linux-gnu libc6-dev-arm64-cross \
-              gnu-efi:arm64 libz-dev:arm64 libpci-dev:arm64 check:arm64 \
+              gnu-efi:arm64 libpci-dev:arm64 check:arm64 \
               qemu-user-static
       - name: Install arm dependencies
         if: ${{ matrix.target == 'arm' }}
@@ -88,7 +88,7 @@ jobs:
           sudo apt-get update
           sudo apt-get install --no-install-recommends \
               autoconf-archive gcc-arm-linux-gnueabihf libc6-dev-armhf-cross \
-              gnu-efi:armhf libz-dev:armhf libpci-dev:armhf check:armhf \
+              gnu-efi:armhf libpci-dev:armhf check:armhf \
               qemu-user-static
       - name: Install riscv64 dependencies
         if: ${{ matrix.target == 'riscv64' }}
@@ -106,7 +106,7 @@ jobs:
           sudo apt-get update
           sudo apt-get install --no-install-recommends \
               autoconf-archive gcc-riscv64-linux-gnu libc6-dev-riscv64-cross \
-              gnu-efi:riscv64 libz-dev:riscv64 libpci-dev:riscv64 check:riscv64 \
+              gnu-efi:riscv64 libpci-dev:riscv64 check:riscv64 \
               qemu-user-static
       - name: Install cppcheck
         if: ${{ matrix.target == 'cppcheck' }}

Makefile.am

@@ -90,6 +90,7 @@ lib_LIBRARIES = libebgenv.a
 libebgenv_a_SOURCES = \
 	env/@[email protected] \
 	env/env_api.c \
+	env/env_api_crc32.c \
 	env/env_config_file.c \
 	env/env_config_partitions.c \
 	env/env_disk_utils.c \
@@ -138,8 +139,7 @@ bg_setenv_LDFLAGS = -Wl,--no-wchar-size-warning
 endif
 
 bg_setenv_LDADD = \
-	$(top_builddir)/libebgenv.a \
-	-lz
+	$(top_builddir)/libebgenv.a
 
 install-exec-hook:
 	$(AM_V_at)$(LN_S) -f bg_setenv$(EXEEXT) \

configure.ac

@@ -138,8 +138,6 @@ AC_CHECK_HEADERS([sys/mount.h])
 AC_CHECK_HEADERS([unistd.h])
 AC_CHECK_HEADERS([wchar.h])
 AC_CHECK_HEADER_STDBOOL
-AC_CHECK_HEADERS([zlib.h])
-AC_CHECK_LIB([z], [crc32], [], [AC_MSG_ERROR([need crc32 implementation from libz])])
 AC_FUNC_GETMNTENT
 AC_PROG_CXX
 AC_TYPE_INT32_T

env/env_api.c

@@ -202,7 +202,7 @@ int ebg_env_setglobalstate(ebgenv_t *e, uint16_t ustate)
 		}
 		if (env->data->ustate != ustate) {
 			env->data->ustate = ustate;
-			env->data->crc32 = crc32(0, (Bytef *)env->data,
+			env->data->crc32 = bgenv_crc32(0, env->data,
 				sizeof(BG_ENVDATA) - sizeof(env->data->crc32));
 			if (!bgenv_write(env)) {
 				bgenv_close(env);
@@ -228,8 +228,8 @@ int ebg_env_close(ebgenv_t *e)
 
 	/* recalculate checksum */
 	env_current->data->crc32 =
-	    crc32(0, (Bytef *)env_current->data,
-		  sizeof(BG_ENVDATA) - sizeof(env_current->data->crc32));
+	    bgenv_crc32(0, env_current->data,
+			sizeof(BG_ENVDATA) - sizeof(env_current->data->crc32));
 	/* save */
 	if (!bgenv_write(env_current)) {
 		res = EIO;

env/env_api_crc32.c

@@ -0,0 +1,114 @@
+/*
+ * EFI Boot Guard
+ *
+ * Copyright (c) Siemens AG, 2023
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * SPDX-License-Identifier:     GPL-2.0
+ */
+
+/*-
+ *  COPYRIGHT (C) 1986 Gary S. Brown.  You may use this program, or
+ *  code or tables extracted from it, as desired without restriction.
+ *
+ *  First, the polynomial itself and its table of feedback terms.  The
+ *  polynomial is
+ *  X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
+ *
+ *  Note that we take it "backwards" and put the highest-order term in
+ *  the lowest-order bit.  The X^32 term is "implied"; the LSB is the
+ *  X^31 term, etc.  The X^0 term (usually shown as "+1") results in
+ *  the MSB being 1
+ *
+ *  Note that the usual hardware shift register implementation, which
+ *  is what we're using (we're merely optimizing it by doing eight-bit
+ *  chunks at a time) shifts bits into the lowest-order term.  In our
+ *  implementation, that means shifting towards the right.  Why do we
+ *  do it this way?  Because the calculated CRC must be transmitted in
+ *  order from highest-order term to lowest-order term.  UARTs transmit
+ *  characters in order from LSB to MSB.  By storing the CRC this way
+ *  we hand it to the UART in the order low-byte to high-byte; the UART
+ *  sends each low-bit to hight-bit; and the result is transmission bit
+ *  by bit from highest- to lowest-order term without requiring any bit
+ *  shuffling on our part.  Reception works similarly
+ *
+ *  The feedback terms table consists of 256, 32-bit entries.  Notes
+ *
+ *      The table can be generated at runtime if desired; code to do so
+ *      is shown later.  It might not be obvious, but the feedback
+ *      terms simply represent the results of eight shift/xor opera
+ *      tions for all combinations of data and CRC register values
+ *
+ *      The values must be right-shifted by eight bits by the "updcrc
+ *      logic; the shift must be unsigned (bring in zeroes).  On some
+ *      hardware you could probably optimize the shift in assembler by
+ *      using byte-swap instructions
+ *      polynomial $edb88320
+ *
+ *
+ * CRC32 code derived from work by Gary S. Brown.
+ */
+
+#include "env_api.h"
+
+static uint32_t crc32_tab[] = {
+	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
+	0xe963a535, 0x9e6495a3,	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
+	0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
+	0xf3b97148, 0x84be41de,	0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,	0x14015c4f, 0x63066cd9,
+	0xfa0f3d63, 0x8d080df5,	0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
+	0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,	0x35b5a8fa, 0x42b2986c,
+	0xdbbbc9d6, 0xacbcf940,	0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
+	0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,	0x76dc4190, 0x01db7106,
+	0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
+	0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
+	0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
+	0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
+	0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
+	0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
+	0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
+	0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
+	0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
+	0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
+	0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
+	0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
+	0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
+	0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
+	0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
+	0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
+	0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
+	0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
+	0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
+	0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+};
+
+uint32_t
+bgenv_crc32(uint32_t crc, const void *buf, size_t size)
+{
+	const uint8_t *p;
+
+	p = buf;
+	crc = crc ^ ~0U;
+
+	while (size--)
+		crc = crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8);
+
+	return crc ^ ~0U;
+}

env/env_api_fat.c

@@ -54,14 +54,14 @@ void bgenv_be_verbose(bool v)
 static void clear_envdata(BG_ENVDATA *data)
 {
 	memset(data, 0, sizeof(BG_ENVDATA));
-	data->crc32 = crc32(0, (Bytef *)data,
-			    sizeof(BG_ENVDATA) - sizeof(data->crc32));
+	data->crc32 = bgenv_crc32(0, data,
+				  sizeof(BG_ENVDATA) - sizeof(data->crc32));
 }
 
 bool validate_envdata(BG_ENVDATA *data)
 {
-	uint32_t sum = crc32(0, (Bytef *)data,
-			     sizeof(BG_ENVDATA) - sizeof(data->crc32));
+	uint32_t sum = bgenv_crc32(0, data,
+				   sizeof(BG_ENVDATA) - sizeof(data->crc32));
 
 	if (data->crc32 != sum) {
 		VERBOSE(stderr, "Invalid CRC32!\n");

include/env_api.h

@@ -28,7 +28,6 @@
 #include <sys/file.h>
 #include <sys/mount.h>
 #include "config.h"
-#include <zlib.h>
 #include "envdata.h"
 #include "ebgenv.h"
 #include <uchar.h>
@@ -80,6 +79,8 @@ extern void bgenv_be_verbose(bool v);
 extern char *str16to8(char *buffer, const char16_t *src);
 extern char16_t *str8to16(char16_t *buffer, const char *src);
 
+extern uint32_t bgenv_crc32(uint32_t, const void *, size_t);
+
 extern bool bgenv_init(void);
 extern void bgenv_finalize(void);
 extern BGENV *bgenv_open_by_index(uint32_t index);

libebgenv.pc.in

@@ -18,6 +18,5 @@ Name: libebgenv
 URL: https://github.com/siemens/efibootguard
 Description: Library to access the EFI Boot Guard environment
 Version: @LIBEBGENV_VERSION@
-Requires.private: zlib
 Libs: -L${libdir} -lebgenv
 Cflags: -I${includedir}

tools/bg_setenv.c

@@ -322,8 +322,9 @@ static void update_environment(BGENV *env, bool verbosity)
 		journal_free_action(action);
 	}
 
-	env->data->crc32 = crc32(0, (const Bytef *)env->data,
-				 sizeof(BG_ENVDATA) - sizeof(env->data->crc32));
+	env->data->crc32 =
+		bgenv_crc32(0, env->data,
+			    sizeof(BG_ENVDATA) - sizeof(env->data->crc32));
 
 }
 

tools/tests/Makefile.am

@@ -37,6 +37,7 @@ endif
 libtest_env_api_fat_a_SRC = \
 	../../env/env_api.c \
 	../../env/env_api_fat.c \
+	../../env/env_api_crc32.c \
 	../../tools/ebgpart.c \
 	../../env/env_config_file.c \
 	../../env/env_config_partitions.c \