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crypto: arc4 - Remove obsolete crypto API support for ARC4

PATCH In review Eric Biggers 3 participants 3 messages Oct 31 – Nov 2

Subsystems (9)
Arm (32-bit) PowerPC MIPS Crypto API +5 more subsystems
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Eric Biggers

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PATCH 1/1 crypto: arc4 - Remove obsolete crypto API support for ARC4

All in-kernel users of ARC4 use the ARC4 library (lib/crypto/arc4.c) directly, not the crypto API wrapper (crypto/arc4.c).

Removal of the crypto API wrapper was attempted in 2020
(https://lore.kernel.org/linux-crypto/[email protected]/)
but was delayed due to its use by iwd via AF_ALG. This was, however, soon afterwards resolved by making iwd simply use userspace ARC4 code
(https://git.kernel.org/pub/scm/network/wireless/iwd.git/commit/?id=1db8a85a60c645232eb5bba1ec0cd0a2927ccd16),
which was released in iwd 1.9 in September 2020.

Also at the time, CONFIG_CRYPTO_ARC4 was placed under CONFIG_CRYPTO_USER_API_ENABLE_OBSOLETE, and the kernel started printing a warning whenever "ecb(arc4)" is used. See commit 9ace67718310 ("crypto: arc4 - mark ecb(arc4) skcipher as obsolete"). So, any other hypothetical user would have had 6 years of deprecation warnings, even if somehow they were overlooking that ARC4 is insecure.

Finally, "ecb(arc4)" isn't on the skcipher_allowlist introduced in v7.3, so it's no longer available in AF_ALG by default even if CONFIG_CRYPTO_ARC4 is enabled.

Given all this, it's clear that the crypto_skcipher / crypto_lskcipher API support for ARC4 is no longer used or needed. Remove it.

The ARC4 library remains in place, as it's still used in the kernel to support certain legacy protocols. (Note: since this removes the only ARC4 test, I'll also add a KUnit test to replace it in a later commit.)

Signed-off-by Eric Biggers <[email protected]>
---
 arch/arm/configs/am200epdkit_defconfig     |  1 -
 arch/arm/configs/spitz_defconfig           |  1 -
 arch/m68k/configs/amiga_defconfig          |  1 -
 arch/m68k/configs/apollo_defconfig         |  1 -
 arch/m68k/configs/atari_defconfig          |  1 -
 arch/m68k/configs/bvme6000_defconfig       |  1 -
 arch/m68k/configs/hp300_defconfig          |  1 -
 arch/m68k/configs/mac_defconfig            |  1 -
 arch/m68k/configs/multi_defconfig          |  1 -
 arch/m68k/configs/mvme147_defconfig        |  1 -
 arch/m68k/configs/mvme16x_defconfig        |  1 -
 arch/m68k/configs/q40_defconfig            |  1 -
 arch/m68k/configs/sun3_defconfig           |  1 -
 arch/m68k/configs/sun3x_defconfig          |  1 -
 arch/mips/configs/decstation_defconfig     |  1 -
 arch/mips/configs/decstation_r4k_defconfig |  1 -
 arch/mips/configs/ip32_defconfig           |  1 -
 arch/mips/configs/rt305x_defconfig         |  1 -
 arch/mips/configs/xway_defconfig           |  1 -
 arch/powerpc/configs/44x/eiger_defconfig   |  1 -
 arch/powerpc/configs/44x/redwood_defconfig |  1 -
 arch/s390/configs/debug_defconfig          |  1 -
 arch/s390/configs/defconfig                |  1 -
 arch/sh/configs/sh2007_defconfig           |  1 -
 arch/sh/configs/titan_defconfig            |  1 -
 arch/sparc/configs/sparc32_defconfig       |  1 -
 crypto/Kconfig                             | 13 ----
 crypto/Makefile                            |  1 -
 crypto/arc4.c                              | 82 ----------------------
 crypto/tcrypt.c                            | 19 -----
 crypto/testmgr.c                           |  7 --
 crypto/testmgr.h                           | 62 ----------------
 include/crypto/arc4.h                      |  3 +-
 33 files changed, 1 insertion(+), 212 deletions(-)
 delete mode 100644 crypto/arc4.c
arch/arm/configs/am200epdkit_defconfig +0 -1
index 61beac88e863..444091e601f2 100644
@@ -85,7 +85,6 @@ CONFIG_DEBUG_KERNEL=y
 CONFIG_CRYPTO=y
 CONFIG_CRYPTO_CBC=m
 CONFIG_CRYPTO_ECB=m
-CONFIG_CRYPTO_ARC4=m
 # CONFIG_DEBUG_BUGVERBOSE is not set
 # CONFIG_DEBUG_PREEMPT is not set
 CONFIG_DEBUG_USER=y
arch/arm/configs/spitz_defconfig +0 -1
index c7cf089001bf..6b988283bc7d 100644
@@ -217,7 +217,6 @@ CONFIG_CRYPTO_ECB=m
 CONFIG_CRYPTO_SHA256=m
 CONFIG_CRYPTO_AES=m
 CONFIG_CRYPTO_ANUBIS=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAST5=m
 CONFIG_CRYPTO_CAST6=m
arch/m68k/configs/amiga_defconfig +0 -1
index e2d474e8cb8f..7a72436f7031 100644
@@ -527,7 +527,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/apollo_defconfig +0 -1
index 77669e31bb5a..5e5a8b9a0019 100644
@@ -481,7 +481,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/atari_defconfig +0 -1
index 43ed1e317ae2..08cbb7e16847 100644
@@ -506,7 +506,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/bvme6000_defconfig +0 -1
index 44c1a2228d5f..794973be69bf 100644
@@ -473,7 +473,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/hp300_defconfig +0 -1
index 7ab25377bfe8..f79c221a6117 100644
@@ -483,7 +483,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/mac_defconfig +0 -1
index 13f642884a94..e08032056392 100644
@@ -502,7 +502,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/multi_defconfig +0 -1
index 1bbd2aa653c0..6aae07476a3f 100644
@@ -592,7 +592,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/mvme147_defconfig +0 -1
index 3bfc36faf8d5..ce0210ed83d8 100644
@@ -473,7 +473,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/mvme16x_defconfig +0 -1
index 41ceed87c78a..2de3a5e2c95b 100644
@@ -474,7 +474,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/q40_defconfig +0 -1
index af4b5c6e4655..8c8ba10f183f 100644
@@ -492,7 +492,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/sun3_defconfig +0 -1
index 1140951fefe7..e637063fec95 100644
@@ -471,7 +471,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/sun3x_defconfig +0 -1
index bc9358e71ee0..ddc1bd7d0ac4 100644
@@ -471,7 +471,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/mips/configs/decstation_defconfig +0 -1
index 29915a002db1..e23784ae9636 100644
@@ -178,7 +178,6 @@ CONFIG_CRYPTO_RMD160=m
 CONFIG_CRYPTO_SHA512=m
 CONFIG_CRYPTO_WP512=m
 CONFIG_CRYPTO_ANUBIS=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAMELLIA=m
 CONFIG_CRYPTO_CAST5=m
arch/mips/configs/decstation_r4k_defconfig +0 -1
index 7eef7a1bdc30..0a81d57ca9c1 100644
@@ -178,7 +178,6 @@ CONFIG_CRYPTO_RMD160=m
 CONFIG_CRYPTO_SHA512=m
 CONFIG_CRYPTO_WP512=m
 CONFIG_CRYPTO_ANUBIS=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAMELLIA=m
 CONFIG_CRYPTO_CAST5=m
arch/mips/configs/ip32_defconfig +0 -1
index 5ddbaa0aafaf..0c3bae4a7bac 100644
@@ -162,7 +162,6 @@ CONFIG_CRYPTO_SHA256=y
 CONFIG_CRYPTO_SHA512=y
 CONFIG_CRYPTO_WP512=y
 CONFIG_CRYPTO_ANUBIS=y
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=y
 CONFIG_CRYPTO_CAMELLIA=y
 CONFIG_CRYPTO_CAST5=y
arch/mips/configs/rt305x_defconfig +0 -1
index c920976bedd0..86327df02681 100644
@@ -126,7 +126,6 @@ CONFIG_JFFS2_COMPRESSION_OPTIONS=y
 CONFIG_SQUASHFS=y
 # CONFIG_SQUASHFS_ZLIB is not set
 CONFIG_SQUASHFS_XZ=y
-CONFIG_CRYPTO_ARC4=m
 # CONFIG_XZ_DEC_X86 is not set
 # CONFIG_XZ_DEC_POWERPC is not set
 # CONFIG_XZ_DEC_IA64 is not set
arch/mips/configs/xway_defconfig +0 -1
index f1c53bbb72e9..74cc4c5cce4c 100644
@@ -138,7 +138,6 @@ CONFIG_JFFS2_COMPRESSION_OPTIONS=y
 CONFIG_SQUASHFS=y
 # CONFIG_SQUASHFS_ZLIB is not set
 CONFIG_SQUASHFS_XZ=y
-CONFIG_CRYPTO_ARC4=m
 CONFIG_PRINTK_TIME=y
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_DEBUG_FS=y
arch/powerpc/configs/44x/eiger_defconfig +0 -1
index 48ab405ab80b..240f3f453b5c 100644
@@ -85,6 +85,5 @@ CONFIG_CRYPTO_MD4=y
 CONFIG_CRYPTO_MD5=y
 CONFIG_CRYPTO_SHA1=y
 CONFIG_CRYPTO_SHA512=y
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=y
 CONFIG_CRYPTO_DES=y
arch/powerpc/configs/44x/redwood_defconfig +0 -1
index 1e883938ca11..a8b93d7a592d 100644
@@ -84,6 +84,5 @@ CONFIG_CRYPTO_MD4=y
 CONFIG_CRYPTO_MD5=y
 CONFIG_CRYPTO_SHA1=y
 CONFIG_CRYPTO_SHA512=y
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=y
 CONFIG_CRYPTO_DES=y
arch/s390/configs/debug_defconfig +0 -1
index d44674b63715..e457b13057d2 100644
@@ -802,7 +802,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_AEGIS128=m
arch/s390/configs/defconfig +0 -1
index e00e252d4694..9e10ac7b1c85 100644
@@ -786,7 +786,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_AEGIS128=m
arch/sh/configs/sh2007_defconfig +0 -1
index 3060bcd9cc5f..ce641ed3a147 100644
@@ -176,7 +176,6 @@ CONFIG_CRYPTO_TGR192=y
 CONFIG_CRYPTO_WP512=y
 CONFIG_CRYPTO_AES=y
 CONFIG_CRYPTO_ANUBIS=y
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=y
 CONFIG_CRYPTO_CAMELLIA=y
 CONFIG_CRYPTO_CAST5=y
arch/sh/configs/titan_defconfig +0 -1
index 00863ecb228e..6f690a0a26d7 100644
@@ -252,7 +252,6 @@ CONFIG_CRYPTO_TGR192=m
 CONFIG_CRYPTO_WP512=m
 CONFIG_CRYPTO_AES=y
 CONFIG_CRYPTO_ANUBIS=m
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAST5=m
 CONFIG_CRYPTO_CAST6=m
arch/sparc/configs/sparc32_defconfig +0 -1
index d5579217fb4c..2f688b83e21b 100644
@@ -84,7 +84,6 @@ CONFIG_CRYPTO_MD4=y
 CONFIG_CRYPTO_SHA256=m
 CONFIG_CRYPTO_SHA512=m
 CONFIG_CRYPTO_AES=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAST5=m
 CONFIG_CRYPTO_CAST6=m
crypto/Kconfig +0 -13
index 981d5dc422d4..2d727f708d9a 100644
@@ -613,19 +613,6 @@ config CRYPTO_ADIANTUM
 
 	  If unsure, say N.
 
-config CRYPTO_ARC4
-	tristate "ARC4 (Alleged Rivest Cipher 4)"
-	depends on CRYPTO_USER_API_ENABLE_OBSOLETE
-	select CRYPTO_SKCIPHER
-	select CRYPTO_LIB_ARC4
-	help
-	  ARC4 cipher algorithm
-
-	  ARC4 is a stream cipher using keys ranging from 8 bits to 2048
-	  bits in length.  This algorithm is required for driver-based
-	  WEP, but it should not be for other purposes because of the
-	  weakness of the algorithm.
-
 config CRYPTO_CHACHA20
 	tristate "ChaCha"
 	select CRYPTO_LIB_CHACHA
crypto/Makefile +0 -1
index 33bb5ad595e8..768a09b7162a 100644
@@ -133,7 +133,6 @@ obj-$(CONFIG_CRYPTO_CAMELLIA) += camellia_generic.o
 obj-$(CONFIG_CRYPTO_CAST_COMMON) += cast_common.o
 obj-$(CONFIG_CRYPTO_CAST5) += cast5_generic.o
 obj-$(CONFIG_CRYPTO_CAST6) += cast6_generic.o
-obj-$(CONFIG_CRYPTO_ARC4) += arc4.o
 obj-$(CONFIG_CRYPTO_TEA) += tea.o
 obj-$(CONFIG_CRYPTO_KHAZAD) += khazad.o
 obj-$(CONFIG_CRYPTO_ANUBIS) += anubis.o
crypto/arc4.c deleted +0 -82

82 lines not on this page · raw message

crypto/tcrypt.c +0 -19
index e6834bdde9b9..579a05d39856 100644
@@ -1579,10 +1579,6 @@ static int do_test(const char *alg, u32 type, u32 mask, int m, u32 num_mb)
 		ret = min(ret, tcrypt_test("xts(cast6)"));
 		break;
 
-	case 16:
-		ret = min(ret, tcrypt_test("ecb(arc4)"));
-		break;
-
 	case 18:
 		ret = min(ret, tcrypt_test("crc32c"));
 		break;

@@ -1995,11 +1991,6 @@ static int do_test(const char *alg, u32 type, u32 mask, int m, u32 num_mb)
 				  speed_template_32_64);
 		break;
 
-	case 208:
-		test_cipher_speed("ecb(arc4)", ENCRYPT, sec, NULL, 0,
-				  speed_template_8);
-		break;
-
 	case 209:
 		test_cipher_speed("ecb(cast5)", ENCRYPT, sec, NULL, 0,
 				  speed_template_8_16);

@@ -2486,11 +2477,6 @@ static int do_test(const char *alg, u32 type, u32 mask, int m, u32 num_mb)
 				   speed_template_32_48_64);
 		break;
 
-	case 505:
-		test_acipher_speed("ecb(arc4)", ENCRYPT, sec, NULL, 0,
-				   speed_template_8);
-		break;
-
 	case 506:
 		test_acipher_speed("ecb(cast5)", ENCRYPT, sec, NULL, 0,
 				   speed_template_8_16);

@@ -2709,11 +2695,6 @@ static int do_test(const char *alg, u32 type, u32 mask, int m, u32 num_mb)
 				       speed_template_32_48_64, num_mb);
 		break;
 
-	case 605:
-		test_mb_skcipher_speed("ecb(arc4)", ENCRYPT, sec, NULL, 0,
-				       speed_template_8, num_mb);
-		break;
-
 	case 606:
 		test_mb_skcipher_speed("ecb(cast5)", ENCRYPT, sec, NULL, 0,
 				       speed_template_8_16, num_mb);
crypto/testmgr.c +0 -7
index 9419d61d0602..094f8e0853f0 100644
@@ -4665,13 +4665,6 @@ static const struct alg_test_desc alg_test_descs[] = {
 		.suite = {
 			.cipher = __VECS(anubis_tv_template)
 		}
-	}, {
-		.alg = "ecb(arc4)",
-		.generic_driver = "arc4-generic",
-		.test = alg_test_skcipher,
-		.suite = {
-			.cipher = __VECS(arc4_tv_template)
-		}
 	}, {
 		.alg = "ecb(aria)",
 		.test = alg_test_skcipher,
crypto/testmgr.h +0 -62

68 lines not on this page · raw message

include/crypto/arc4.h +1 -2
index f3c22fe01704..f88a5fb85c9a 100644
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0+ */
 /*
- * Common values for ARC4 Cipher Algorithm
+ * ARC4 Cipher Algorithm
  */
 
 #ifndef _CRYPTO_ARC4_H

@@ -10,7 +10,6 @@
 
 #define ARC4_MIN_KEY_SIZE	1
 #define ARC4_MAX_KEY_SIZE	256
-#define ARC4_BLOCK_SIZE		1
 
 struct arc4_ctx {
 	u32 S[256];

base-commit: e9954f3fbddd25e1a01b7e5a0b72fb8b564204e0

Signature · 1 line
2.56.0
Reviewed-by on v1 1/1
#1 lore raw
Quoted 57 lines · Eric Biggers

All in-kernel users of ARC4 use the ARC4 library (lib/crypto/arc4.c) directly, not the crypto API wrapper (crypto/arc4.c).

Removal of the crypto API wrapper was attempted in 2020
(https://lore.kernel.org/linux-crypto/[email protected]/)
but was delayed due to its use by iwd via AF_ALG. This was, however, soon afterwards resolved by making iwd simply use userspace ARC4 code
(https://git.kernel.org/pub/scm/network/wireless/iwd.git/commit/?id=1db8a85a60c645232eb5bba1ec0cd0a2927ccd16),
which was released in iwd 1.9 in September 2020.

Also at the time, CONFIG_CRYPTO_ARC4 was placed under CONFIG_CRYPTO_USER_API_ENABLE_OBSOLETE, and the kernel started printing a warning whenever "ecb(arc4)" is used. See commit 9ace67718310 ("crypto: arc4 - mark ecb(arc4) skcipher as obsolete"). So, any other hypothetical user would have had 6 years of deprecation warnings, even if somehow they were overlooking that ARC4 is insecure.

Finally, "ecb(arc4)" isn't on the skcipher_allowlist introduced in v7.3, so it's no longer available in AF_ALG by default even if CONFIG_CRYPTO_ARC4 is enabled.

Given all this, it's clear that the crypto_skcipher / crypto_lskcipher API support for ARC4 is no longer used or needed. Remove it.

The ARC4 library remains in place, as it's still used in the kernel to support certain legacy protocols. (Note: since this removes the only ARC4 test, I'll also add a KUnit test to replace it in a later commit.)

Signed-off-by Eric Biggers <[email protected]>
---
 arch/arm/configs/am200epdkit_defconfig     |  1 -
 arch/arm/configs/spitz_defconfig           |  1 -
 arch/m68k/configs/amiga_defconfig          |  1 -
 arch/m68k/configs/apollo_defconfig         |  1 -
 arch/m68k/configs/atari_defconfig          |  1 -
 arch/m68k/configs/bvme6000_defconfig       |  1 -
 arch/m68k/configs/hp300_defconfig          |  1 -
 arch/m68k/configs/mac_defconfig            |  1 -
 arch/m68k/configs/multi_defconfig          |  1 -
 arch/m68k/configs/mvme147_defconfig        |  1 -
 arch/m68k/configs/mvme16x_defconfig        |  1 -
 arch/m68k/configs/q40_defconfig            |  1 -
 arch/m68k/configs/sun3_defconfig           |  1 -
 arch/m68k/configs/sun3x_defconfig          |  1 -
 arch/mips/configs/decstation_defconfig     |  1 -
 arch/mips/configs/decstation_r4k_defconfig |  1 -
 arch/mips/configs/ip32_defconfig           |  1 -
 arch/mips/configs/rt305x_defconfig         |  1 -
 arch/mips/configs/xway_defconfig           |  1 -
 arch/powerpc/configs/44x/eiger_defconfig   |  1 -
 arch/powerpc/configs/44x/redwood_defconfig |  1 -
 arch/s390/configs/debug_defconfig          |  1 -
 arch/s390/configs/defconfig                |  1 -
 arch/sh/configs/sh2007_defconfig           |  1 -
 arch/sh/configs/titan_defconfig            |  1 -
 arch/sparc/configs/sparc32_defconfig       |  1 -
 crypto/Kconfig                             | 13 ----
Quoted 9 lines
 crypto/Makefile                            |  1 -
 crypto/arc4.c                              | 82 ----------------------
 crypto/tcrypt.c                            | 19 -----
 crypto/testmgr.c                           |  7 --
 crypto/testmgr.h                           | 62 ----------------
 include/crypto/arc4.h                      |  3 +-
 33 files changed, 1 insertion(+), 212 deletions(-)
 delete mode 100644 crypto/arc4.c

Good riddance.

Reviewed-by Ard Biesheuvel <[email protected]>
Quoted 633 lines
arch/arm/configs/am200epdkit_defconfig +0 -1
index 61beac88e863..444091e601f2 100644
@@ -85,7 +85,6 @@ CONFIG_DEBUG_KERNEL=y
 CONFIG_CRYPTO=y
 CONFIG_CRYPTO_CBC=m
 CONFIG_CRYPTO_ECB=m
-CONFIG_CRYPTO_ARC4=m
 # CONFIG_DEBUG_BUGVERBOSE is not set
 # CONFIG_DEBUG_PREEMPT is not set
 CONFIG_DEBUG_USER=y
arch/arm/configs/spitz_defconfig +0 -1
index c7cf089001bf..6b988283bc7d 100644
@@ -217,7 +217,6 @@ CONFIG_CRYPTO_ECB=m
 CONFIG_CRYPTO_SHA256=m
 CONFIG_CRYPTO_AES=m
 CONFIG_CRYPTO_ANUBIS=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAST5=m
 CONFIG_CRYPTO_CAST6=m
arch/m68k/configs/amiga_defconfig +0 -1
index e2d474e8cb8f..7a72436f7031 100644
@@ -527,7 +527,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/apollo_defconfig +0 -1
index 77669e31bb5a..5e5a8b9a0019 100644
@@ -481,7 +481,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/atari_defconfig +0 -1
index 43ed1e317ae2..08cbb7e16847 100644
@@ -506,7 +506,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/bvme6000_defconfig +0 -1
index 44c1a2228d5f..794973be69bf 100644
@@ -473,7 +473,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/hp300_defconfig +0 -1
index 7ab25377bfe8..f79c221a6117 100644
@@ -483,7 +483,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/mac_defconfig +0 -1
index 13f642884a94..e08032056392 100644
@@ -502,7 +502,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/multi_defconfig +0 -1
index 1bbd2aa653c0..6aae07476a3f 100644
@@ -592,7 +592,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/mvme147_defconfig +0 -1
index 3bfc36faf8d5..ce0210ed83d8 100644
@@ -473,7 +473,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/mvme16x_defconfig +0 -1
index 41ceed87c78a..2de3a5e2c95b 100644
@@ -474,7 +474,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/q40_defconfig +0 -1
index af4b5c6e4655..8c8ba10f183f 100644
@@ -492,7 +492,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/sun3_defconfig +0 -1
index 1140951fefe7..e637063fec95 100644
@@ -471,7 +471,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/m68k/configs/sun3x_defconfig +0 -1
index bc9358e71ee0..ddc1bd7d0ac4 100644
@@ -471,7 +471,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_XTS=m
arch/mips/configs/decstation_defconfig +0 -1
index 29915a002db1..e23784ae9636 100644
@@ -178,7 +178,6 @@ CONFIG_CRYPTO_RMD160=m
 CONFIG_CRYPTO_SHA512=m
 CONFIG_CRYPTO_WP512=m
 CONFIG_CRYPTO_ANUBIS=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAMELLIA=m
 CONFIG_CRYPTO_CAST5=m
arch/mips/configs/decstation_r4k_defconfig +0 -1
index 7eef7a1bdc30..0a81d57ca9c1 100644
@@ -178,7 +178,6 @@ CONFIG_CRYPTO_RMD160=m
 CONFIG_CRYPTO_SHA512=m
 CONFIG_CRYPTO_WP512=m
 CONFIG_CRYPTO_ANUBIS=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAMELLIA=m
 CONFIG_CRYPTO_CAST5=m
arch/mips/configs/ip32_defconfig +0 -1
index 5ddbaa0aafaf..0c3bae4a7bac 100644
@@ -162,7 +162,6 @@ CONFIG_CRYPTO_SHA256=y
 CONFIG_CRYPTO_SHA512=y
 CONFIG_CRYPTO_WP512=y
 CONFIG_CRYPTO_ANUBIS=y
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=y
 CONFIG_CRYPTO_CAMELLIA=y
 CONFIG_CRYPTO_CAST5=y
arch/mips/configs/rt305x_defconfig +0 -1
index c920976bedd0..86327df02681 100644
@@ -126,7 +126,6 @@ CONFIG_JFFS2_COMPRESSION_OPTIONS=y
 CONFIG_SQUASHFS=y
 # CONFIG_SQUASHFS_ZLIB is not set
 CONFIG_SQUASHFS_XZ=y
-CONFIG_CRYPTO_ARC4=m
 # CONFIG_XZ_DEC_X86 is not set
 # CONFIG_XZ_DEC_POWERPC is not set
 # CONFIG_XZ_DEC_IA64 is not set
arch/mips/configs/xway_defconfig +0 -1
index f1c53bbb72e9..74cc4c5cce4c 100644
@@ -138,7 +138,6 @@ CONFIG_JFFS2_COMPRESSION_OPTIONS=y
 CONFIG_SQUASHFS=y
 # CONFIG_SQUASHFS_ZLIB is not set
 CONFIG_SQUASHFS_XZ=y
-CONFIG_CRYPTO_ARC4=m
 CONFIG_PRINTK_TIME=y
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_DEBUG_FS=y
arch/powerpc/configs/44x/eiger_defconfig +0 -1
index 48ab405ab80b..240f3f453b5c 100644
@@ -85,6 +85,5 @@ CONFIG_CRYPTO_MD4=y
 CONFIG_CRYPTO_MD5=y
 CONFIG_CRYPTO_SHA1=y
 CONFIG_CRYPTO_SHA512=y
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=y
 CONFIG_CRYPTO_DES=y
arch/powerpc/configs/44x/redwood_defconfig +0 -1
index 1e883938ca11..a8b93d7a592d 100644
@@ -84,6 +84,5 @@ CONFIG_CRYPTO_MD4=y
 CONFIG_CRYPTO_MD5=y
 CONFIG_CRYPTO_SHA1=y
 CONFIG_CRYPTO_SHA512=y
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=y
 CONFIG_CRYPTO_DES=y
arch/s390/configs/debug_defconfig +0 -1
index d44674b63715..e457b13057d2 100644
@@ -802,7 +802,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_AEGIS128=m
arch/s390/configs/defconfig +0 -1
index e00e252d4694..9e10ac7b1c85 100644
@@ -786,7 +786,6 @@ CONFIG_CRYPTO_SM4_GENERIC=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
 CONFIG_CRYPTO_ADIANTUM=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_HCTR2=m
 CONFIG_CRYPTO_LRW=m
 CONFIG_CRYPTO_AEGIS128=m
arch/sh/configs/sh2007_defconfig +0 -1
index 3060bcd9cc5f..ce641ed3a147 100644
@@ -176,7 +176,6 @@ CONFIG_CRYPTO_TGR192=y
 CONFIG_CRYPTO_WP512=y
 CONFIG_CRYPTO_AES=y
 CONFIG_CRYPTO_ANUBIS=y
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=y
 CONFIG_CRYPTO_CAMELLIA=y
 CONFIG_CRYPTO_CAST5=y
arch/sh/configs/titan_defconfig +0 -1
index 00863ecb228e..6f690a0a26d7 100644
@@ -252,7 +252,6 @@ CONFIG_CRYPTO_TGR192=m
 CONFIG_CRYPTO_WP512=m
 CONFIG_CRYPTO_AES=y
 CONFIG_CRYPTO_ANUBIS=m
-CONFIG_CRYPTO_ARC4=y
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAST5=m
 CONFIG_CRYPTO_CAST6=m
arch/sparc/configs/sparc32_defconfig +0 -1
index d5579217fb4c..2f688b83e21b 100644
@@ -84,7 +84,6 @@ CONFIG_CRYPTO_MD4=y
 CONFIG_CRYPTO_SHA256=m
 CONFIG_CRYPTO_SHA512=m
 CONFIG_CRYPTO_AES=m
-CONFIG_CRYPTO_ARC4=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAST5=m
 CONFIG_CRYPTO_CAST6=m
crypto/Kconfig +0 -13
index 981d5dc422d4..2d727f708d9a 100644
@@ -613,19 +613,6 @@ config CRYPTO_ADIANTUM
 
 	  If unsure, say N.
 
-config CRYPTO_ARC4
-	tristate "ARC4 (Alleged Rivest Cipher 4)"
-	depends on CRYPTO_USER_API_ENABLE_OBSOLETE
-	select CRYPTO_SKCIPHER
-	select CRYPTO_LIB_ARC4
-	help
-	  ARC4 cipher algorithm
-
-	  ARC4 is a stream cipher using keys ranging from 8 bits to 2048
-	  bits in length.  This algorithm is required for driver-based
-	  WEP, but it should not be for other purposes because of the
-	  weakness of the algorithm.
-
 config CRYPTO_CHACHA20
 	tristate "ChaCha"
 	select CRYPTO_LIB_CHACHA
crypto/Makefile +0 -1
index 33bb5ad595e8..768a09b7162a 100644
@@ -133,7 +133,6 @@ obj-$(CONFIG_CRYPTO_CAMELLIA) += camellia_generic.o
 obj-$(CONFIG_CRYPTO_CAST_COMMON) += cast_common.o
 obj-$(CONFIG_CRYPTO_CAST5) += cast5_generic.o
 obj-$(CONFIG_CRYPTO_CAST6) += cast6_generic.o
-obj-$(CONFIG_CRYPTO_ARC4) += arc4.o
 obj-$(CONFIG_CRYPTO_TEA) += tea.o
 obj-$(CONFIG_CRYPTO_KHAZAD) += khazad.o
 obj-$(CONFIG_CRYPTO_ANUBIS) += anubis.o
crypto/arc4.c deleted +0 -19
deleted file mode 100644
index 1608018111d0..000000000000
@@ -1,82 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * Cryptographic API
- *
- * ARC4 Cipher Algorithm
- *
- * Jon Oberheide <[email protected]>
- */
-
-#include <crypto/arc4.h>
-#include <crypto/internal/skcipher.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/sched.h>
-
-#define ARC4_ALIGN __alignof__(struct arc4_ctx)
-
-static int crypto_arc4_setkey(struct crypto_lskcipher *tfm, const u8

*in_key,

crypto/arc4.c deleted +0 -8
-			      unsigned int key_len)
-{
-	struct arc4_ctx *ctx = crypto_lskcipher_ctx(tfm);
-
-	return arc4_setkey(ctx, in_key, key_len);
-}
-
-static int crypto_arc4_crypt(struct crypto_lskcipher *tfm, const u8

*src,

crypto/arc4.c deleted +0 -55
-			     u8 *dst, unsigned nbytes, u8 *siv, u32 flags)
-{
-	struct arc4_ctx *ctx = crypto_lskcipher_ctx(tfm);
-
-	if (!(flags & CRYPTO_LSKCIPHER_FLAG_CONT))
-		memcpy(siv, ctx, sizeof(*ctx));
-
-	ctx = (struct arc4_ctx *)siv;
-
-	arc4_crypt(ctx, dst, src, nbytes);
-	return 0;
-}
-
-static int crypto_arc4_init(struct crypto_lskcipher *tfm)
-{
-	pr_warn_ratelimited("\"%s\" (%ld) uses obsolete ecb(arc4) skcipher\n",
-			    current->comm, (unsigned long)current->pid);
-
-	return 0;
-}
-
-static struct lskcipher_alg arc4_alg = {
-	.co.base.cra_name		=	"arc4",
-	.co.base.cra_driver_name	=	"arc4-generic",
-	.co.base.cra_priority		=	100,
-	.co.base.cra_blocksize		=	ARC4_BLOCK_SIZE,
-	.co.base.cra_ctxsize		=	sizeof(struct arc4_ctx),
-	.co.base.cra_alignmask		=	ARC4_ALIGN - 1,
-	.co.base.cra_module		=	THIS_MODULE,
-	.co.min_keysize			=	ARC4_MIN_KEY_SIZE,
-	.co.max_keysize			=	ARC4_MAX_KEY_SIZE,
-	.co.statesize			=	sizeof(struct arc4_ctx),
-	.setkey				=	crypto_arc4_setkey,
-	.encrypt			=	crypto_arc4_crypt,
-	.decrypt			=	crypto_arc4_crypt,
-	.init				=	crypto_arc4_init,
-};
-
-static int __init arc4_init(void)
-{
-	return crypto_register_lskcipher(&arc4_alg);
-}
-
-static void __exit arc4_exit(void)
-{
-	crypto_unregister_lskcipher(&arc4_alg);
-}
-
-module_init(arc4_init);
-module_exit(arc4_exit);
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
-MODULE_AUTHOR("Jon Oberheide <[email protected]>");
-MODULE_ALIAS_CRYPTO("ecb(arc4)");
crypto/tcrypt.c +0 -4
index e6834bdde9b9..579a05d39856 100644
@@ -1579,10 +1579,6 @@ static int do_test(const char *alg, u32 type, 
 u32 mask, int m, u32 num_mb)
 		ret = min(ret, tcrypt_test("xts(cast6)"));
 		break;
 
-	case 16:
-		ret = min(ret, tcrypt_test("ecb(arc4)"));
-		break;
-
 	case 18:
 		ret = min(ret, tcrypt_test("crc32c"));
crypto/tcrypt.c +0 -5
 		break;

@@ -1995,11 +1991,6 @@ static int do_test(const char *alg, u32 type, 
 u32 mask, int m, u32 num_mb)
 				  speed_template_32_64);
 		break;
 
-	case 208:
-		test_cipher_speed("ecb(arc4)", ENCRYPT, sec, NULL, 0,
-				  speed_template_8);
-		break;
-
 	case 209:
 		test_cipher_speed("ecb(cast5)", ENCRYPT, sec, NULL, 0,
crypto/tcrypt.c +0 -5
 				  speed_template_8_16);

@@ -2486,11 +2477,6 @@ static int do_test(const char *alg, u32 type, 
 u32 mask, int m, u32 num_mb)
 				   speed_template_32_48_64);
 		break;
 
-	case 505:
-		test_acipher_speed("ecb(arc4)", ENCRYPT, sec, NULL, 0,
-				   speed_template_8);
-		break;
-
 	case 506:
 		test_acipher_speed("ecb(cast5)", ENCRYPT, sec, NULL, 0,
crypto/tcrypt.c +0 -5
 				   speed_template_8_16);

@@ -2709,11 +2695,6 @@ static int do_test(const char *alg, u32 type, 
 u32 mask, int m, u32 num_mb)
 				       speed_template_32_48_64, num_mb);
 		break;
 
-	case 605:
-		test_mb_skcipher_speed("ecb(arc4)", ENCRYPT, sec, NULL, 0,
-				       speed_template_8, num_mb);
-		break;
-
 	case 606:
 		test_mb_skcipher_speed("ecb(cast5)", ENCRYPT, sec, NULL, 0,
crypto/tcrypt.c +0 -0
 				       speed_template_8_16, num_mb);
crypto/testmgr.c +0 -7
index 9419d61d0602..094f8e0853f0 100644
@@ -4665,13 +4665,6 @@ static const struct alg_test_desc 
 alg_test_descs[] = {
 		.suite = {
 			.cipher = __VECS(anubis_tv_template)
 		}
-	}, {
-		.alg = "ecb(arc4)",
-		.generic_driver = "arc4-generic",
-		.test = alg_test_skcipher,
-		.suite = {
-			.cipher = __VECS(arc4_tv_template)
-		}
 	}, {
 		.alg = "ecb(aria)",
crypto/testmgr.c +0 -0
 		.test = alg_test_skcipher,
crypto/testmgr.h +0 -62
index 0ee15a8fae27..a7f096b0830e 100644
@@ -24388,68 +24388,6 @@ static const struct cipher_testvec 
 cast5_ctr_tv_template[] = {
 	},
 };
 
-/*
- * ARC4 test vectors from OpenSSL
- */
-static const struct cipher_testvec arc4_tv_template[] = {
-	{
-		.key	= "\x01\x23\x45\x67\x89\xab\xcd\xef",
-		.klen	= 8,
-		.ptext	= "\x01\x23\x45\x67\x89\xab\xcd\xef",
-		.ctext	= "\x75\xb7\x87\x80\x99\xe0\xc5\x96",
-		.len	= 8,
-	}, {
-		.key	= "\x01\x23\x45\x67\x89\xab\xcd\xef",
-		.klen	= 8,
-		.ptext	= "\x00\x00\x00\x00\x00\x00\x00\x00",
-		.ctext	= "\x74\x94\xc2\xe7\x10\x4b\x08\x79",
-		.len	= 8,
-	}, {
-		.key	= "\x00\x00\x00\x00\x00\x00\x00\x00",
-		.klen	= 8,
-		.ptext	= "\x00\x00\x00\x00\x00\x00\x00\x00",
-		.ctext	= "\xde\x18\x89\x41\xa3\x37\x5d\x3a",
-		.len	= 8,
-	}, {
-		.key	= "\xef\x01\x23\x45",
-		.klen	= 4,
-		.ptext	= "\x00\x00\x00\x00\x00\x00\x00\x00"
-			  "\x00\x00\x00\x00\x00\x00\x00\x00"
-			  "\x00\x00\x00\x00",
-		.ctext	= "\xd6\xa1\x41\xa7\xec\x3c\x38\xdf"
-			  "\xbd\x61\x5a\x11\x62\xe1\xc7\xba"
-			  "\x36\xb6\x78\x58",
-		.len	= 20,
-	}, {
-		.key	= "\x01\x23\x45\x67\x89\xab\xcd\xef",
-		.klen	= 8,
-		.ptext	= "\x12\x34\x56\x78\x9A\xBC\xDE\xF0"
-			  "\x12\x34\x56\x78\x9A\xBC\xDE\xF0"
-			  "\x12\x34\x56\x78\x9A\xBC\xDE\xF0"
-			  "\x12\x34\x56\x78",
-		.ctext	= "\x66\xa0\x94\x9f\x8a\xf7\xd6\x89"
-			  "\x1f\x7f\x83\x2b\xa8\x33\xc0\x0c"
-			  "\x89\x2e\xbe\x30\x14\x3c\xe2\x87"
-			  "\x40\x01\x1e\xcf",
-		.len	= 28,
-	}, {
-		.key	= "\xef\x01\x23\x45",
-		.klen	= 4,
-		.ptext	= "\x00\x00\x00\x00\x00\x00\x00\x00"
-			  "\x00\x00",
-		.ctext	= "\xd6\xa1\x41\xa7\xec\x3c\x38\xdf"
-			  "\xbd\x61",
-		.len	= 10,
-	}, {
-		.key	= "\x01\x23\x45\x67\x89\xAB\xCD\xEF"
-			"\x00\x00\x00\x00\x00\x00\x00\x00",
-		.klen	= 16,
-		.ptext	= "\x01\x23\x45\x67\x89\xAB\xCD\xEF",
-		.ctext	= "\x69\x72\x36\x59\x1B\x52\x42\xB1",
-		.len	= 8,
-	},
-};
-
 /*
  * TEA test vectors

*/

include/crypto/arc4.h +1 -2
index f3c22fe01704..f88a5fb85c9a 100644
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0+ */
 /*
- * Common values for ARC4 Cipher Algorithm
+ * ARC4 Cipher Algorithm
  */
 
 #ifndef _CRYPTO_ARC4_H

@@ -10,7 +10,6 @@
 
 #define ARC4_MIN_KEY_SIZE	1
 #define ARC4_MAX_KEY_SIZE	256
-#define ARC4_BLOCK_SIZE		1
 
 struct arc4_ctx {
 	u32 S[256];

base-commit: e9954f3fbddd25e1a01b7e5a0b72fb8b564204e0

Signature · 1 line
2.56.0
Reviewed-by on v1 1/1
#2 lore raw
In reply to Eric Biggers
Quoted 64 lines · Eric Biggers

All in-kernel users of ARC4 use the ARC4 library (lib/crypto/arc4.c) directly, not the crypto API wrapper (crypto/arc4.c).

Removal of the crypto API wrapper was attempted in 2020
(https://lore.kernel.org/linux-crypto/[email protected]/)
but was delayed due to its use by iwd via AF_ALG. This was, however, soon afterwards resolved by making iwd simply use userspace ARC4 code
(https://git.kernel.org/pub/scm/network/wireless/iwd.git/commit/?id=1db8a85a60c645232eb5bba1ec0cd0a2927ccd16),
which was released in iwd 1.9 in September 2020.

Also at the time, CONFIG_CRYPTO_ARC4 was placed under CONFIG_CRYPTO_USER_API_ENABLE_OBSOLETE, and the kernel started printing a warning whenever "ecb(arc4)" is used. See commit 9ace67718310 ("crypto: arc4 - mark ecb(arc4) skcipher as obsolete"). So, any other hypothetical user would have had 6 years of deprecation warnings, even if somehow they were overlooking that ARC4 is insecure.

Finally, "ecb(arc4)" isn't on the skcipher_allowlist introduced in v7.3, so it's no longer available in AF_ALG by default even if CONFIG_CRYPTO_ARC4 is enabled.

Given all this, it's clear that the crypto_skcipher / crypto_lskcipher API support for ARC4 is no longer used or needed. Remove it.

The ARC4 library remains in place, as it's still used in the kernel to support certain legacy protocols. (Note: since this removes the only ARC4 test, I'll also add a KUnit test to replace it in a later commit.)

Signed-off-by Eric Biggers <[email protected]>
---
  arch/arm/configs/am200epdkit_defconfig     |  1 -
  arch/arm/configs/spitz_defconfig           |  1 -
  arch/m68k/configs/amiga_defconfig          |  1 -
  arch/m68k/configs/apollo_defconfig         |  1 -
  arch/m68k/configs/atari_defconfig          |  1 -
  arch/m68k/configs/bvme6000_defconfig       |  1 -
  arch/m68k/configs/hp300_defconfig          |  1 -
  arch/m68k/configs/mac_defconfig            |  1 -
  arch/m68k/configs/multi_defconfig          |  1 -
  arch/m68k/configs/mvme147_defconfig        |  1 -
  arch/m68k/configs/mvme16x_defconfig        |  1 -
  arch/m68k/configs/q40_defconfig            |  1 -
  arch/m68k/configs/sun3_defconfig           |  1 -
  arch/m68k/configs/sun3x_defconfig          |  1 -
  arch/mips/configs/decstation_defconfig     |  1 -
  arch/mips/configs/decstation_r4k_defconfig |  1 -
  arch/mips/configs/ip32_defconfig           |  1 -
  arch/mips/configs/rt305x_defconfig         |  1 -
  arch/mips/configs/xway_defconfig           |  1 -
  arch/powerpc/configs/44x/eiger_defconfig   |  1 -
  arch/powerpc/configs/44x/redwood_defconfig |  1 -
  arch/s390/configs/debug_defconfig          |  1 -
  arch/s390/configs/defconfig                |  1 -
  arch/sh/configs/sh2007_defconfig           |  1 -
  arch/sh/configs/titan_defconfig            |  1 -
  arch/sparc/configs/sparc32_defconfig       |  1 -
  crypto/Kconfig                             | 13 ----
  crypto/Makefile                            |  1 -
  crypto/arc4.c                              | 82 ----------------------
  crypto/tcrypt.c                            | 19 -----
  crypto/testmgr.c                           |  7 --
  crypto/testmgr.h                           | 62 ----------------
  include/crypto/arc4.h                      |  3 +-
  33 files changed, 1 insertion(+), 212 deletions(-)
Quoted 1 line

delete mode 100644 crypto/arc4.c

Reviewed-by Thomas Huth <[email protected]>