Changelog:
v3:
- Fixed a bug in READ_PARTIAL_BLOCK when used for reading the AAD
- Some refactoring per CR feedback
v2:
- Also fixed issue 2 described below
v1:
- Fixed issue 1 described below
The aesni_gcm_enc/dec functions can access memory before the start or end of
the supplied src buffer. This can happen if either:
1. The data length is less than 16 bytes and there is no AAD or the AAD
length is not enough to cover the underrun. In this case, memory before
the start of the buffer would be accessed.
2. The AAD length is not a multiple of 4 bytes and the data length is too
small to cover the overrun. In this case, memory after the end of the
buffer would be accessed.
This was not a problem when rfc4106-gcm-aesni was the only mode supported by
the aesni module, as in that case there is always enough AAD and IV bytes to
cover the out-of-bounds accesses. However, that is no longer the case with
the generic-gcm-aesni mode. This could potentially result in accessing pages
that are not mapped, thus causing a crash.
Junaid Shahid (2):
crypto: Fix out-of-bounds access of the data buffer in
generic-gcm-aesni
crypto: Fix out-of-bounds access of the AAD buffer in
generic-gcm-aesni
arch/x86/crypto/aesni-intel_asm.S | 199 +++++++++++---------------------------
1 file changed, 57 insertions(+), 142 deletions(-)
--
2.15.1.620.gb9897f4670-goog
The aesni_gcm_enc/dec functions can access memory before the start of
the data buffer if the length of the data buffer is less than 16 bytes.
This is because they perform the read via a single 16-byte load. This
can potentially result in accessing a page that is not mapped and thus
causing the machine to crash. This patch fixes that by reading the
partial block byte-by-byte and optionally an via 8-byte load if the block
was at least 8 bytes.
Fixes: 0487ccac ("crypto: aesni - make non-AVX AES-GCM work with any aadlen")
Signed-off-by: Junaid Shahid <[email protected]>
---
arch/x86/crypto/aesni-intel_asm.S | 87 ++++++++++++++++++++-------------------
1 file changed, 45 insertions(+), 42 deletions(-)
diff --git a/arch/x86/crypto/aesni-intel_asm.S b/arch/x86/crypto/aesni-intel_asm.S
index 16627fec80b2..c36b850fdc81 100644
--- a/arch/x86/crypto/aesni-intel_asm.S
+++ b/arch/x86/crypto/aesni-intel_asm.S
@@ -256,6 +256,37 @@ aad_shift_arr:
pxor \TMP1, \GH # result is in TMP1
.endm
+# Reads DLEN bytes starting at DPTR and stores in XMMDst
+# where 0 < DLEN < 16
+# Clobbers %rax, DLEN and XMM1
+.macro READ_PARTIAL_BLOCK DPTR DLEN XMM1 XMMDst
+ cmp $8, \DLEN
+ jl _read_lt8_\@
+ mov (\DPTR), %rax
+ MOVQ_R64_XMM %rax, \XMMDst
+ sub $8, \DLEN
+ jz _done_read_partial_block_\@
+ xor %eax, %eax
+_read_next_byte_\@:
+ shl $8, %rax
+ mov 7(\DPTR, \DLEN, 1), %al
+ dec \DLEN
+ jnz _read_next_byte_\@
+ MOVQ_R64_XMM %rax, \XMM1
+ pslldq $8, \XMM1
+ por \XMM1, \XMMDst
+ jmp _done_read_partial_block_\@
+_read_lt8_\@:
+ xor %eax, %eax
+_read_next_byte_lt8_\@:
+ shl $8, %rax
+ mov -1(\DPTR, \DLEN, 1), %al
+ dec \DLEN
+ jnz _read_next_byte_lt8_\@
+ MOVQ_R64_XMM %rax, \XMMDst
+_done_read_partial_block_\@:
+.endm
+
/*
* if a = number of total plaintext bytes
* b = floor(a/16)
@@ -1385,14 +1416,6 @@ _esb_loop_\@:
*
* AAD Format with 64-bit Extended Sequence Number
*
-* aadLen:
-* from the definition of the spec, aadLen can only be 8 or 12 bytes.
-* The code supports 16 too but for other sizes, the code will fail.
-*
-* TLen:
-* from the definition of the spec, TLen can only be 8, 12 or 16 bytes.
-* For other sizes, the code will fail.
-*
* poly = x^128 + x^127 + x^126 + x^121 + 1
*
*****************************************************************************/
@@ -1486,19 +1509,16 @@ _zero_cipher_left_decrypt:
PSHUFB_XMM %xmm10, %xmm0
ENCRYPT_SINGLE_BLOCK %xmm0, %xmm1 # E(K, Yn)
- sub $16, %r11
- add %r13, %r11
- movdqu (%arg3,%r11,1), %xmm1 # receive the last <16 byte block
- lea SHIFT_MASK+16(%rip), %r12
- sub %r13, %r12
-# adjust the shuffle mask pointer to be able to shift 16-%r13 bytes
-# (%r13 is the number of bytes in plaintext mod 16)
- movdqu (%r12), %xmm2 # get the appropriate shuffle mask
- PSHUFB_XMM %xmm2, %xmm1 # right shift 16-%r13 butes
+ lea (%arg3,%r11,1), %r10
+ mov %r13, %r12
+ READ_PARTIAL_BLOCK %r10 %r12 %xmm2 %xmm1
+
+ lea ALL_F+16(%rip), %r12
+ sub %r13, %r12
movdqa %xmm1, %xmm2
pxor %xmm1, %xmm0 # Ciphertext XOR E(K, Yn)
- movdqu ALL_F-SHIFT_MASK(%r12), %xmm1
+ movdqu (%r12), %xmm1
# get the appropriate mask to mask out top 16-%r13 bytes of %xmm0
pand %xmm1, %xmm0 # mask out top 16-%r13 bytes of %xmm0
pand %xmm1, %xmm2
@@ -1507,9 +1527,6 @@ _zero_cipher_left_decrypt:
pxor %xmm2, %xmm8
GHASH_MUL %xmm8, %xmm13, %xmm9, %xmm10, %xmm11, %xmm5, %xmm6
- # GHASH computation for the last <16 byte block
- sub %r13, %r11
- add $16, %r11
# output %r13 bytes
MOVQ_R64_XMM %xmm0, %rax
@@ -1663,14 +1680,6 @@ ENDPROC(aesni_gcm_dec)
*
* AAD Format with 64-bit Extended Sequence Number
*
-* aadLen:
-* from the definition of the spec, aadLen can only be 8 or 12 bytes.
-* The code supports 16 too but for other sizes, the code will fail.
-*
-* TLen:
-* from the definition of the spec, TLen can only be 8, 12 or 16 bytes.
-* For other sizes, the code will fail.
-*
* poly = x^128 + x^127 + x^126 + x^121 + 1
***************************************************************************/
ENTRY(aesni_gcm_enc)
@@ -1763,19 +1772,16 @@ _zero_cipher_left_encrypt:
movdqa SHUF_MASK(%rip), %xmm10
PSHUFB_XMM %xmm10, %xmm0
-
ENCRYPT_SINGLE_BLOCK %xmm0, %xmm1 # Encrypt(K, Yn)
- sub $16, %r11
- add %r13, %r11
- movdqu (%arg3,%r11,1), %xmm1 # receive the last <16 byte blocks
- lea SHIFT_MASK+16(%rip), %r12
+
+ lea (%arg3,%r11,1), %r10
+ mov %r13, %r12
+ READ_PARTIAL_BLOCK %r10 %r12 %xmm2 %xmm1
+
+ lea ALL_F+16(%rip), %r12
sub %r13, %r12
- # adjust the shuffle mask pointer to be able to shift 16-r13 bytes
- # (%r13 is the number of bytes in plaintext mod 16)
- movdqu (%r12), %xmm2 # get the appropriate shuffle mask
- PSHUFB_XMM %xmm2, %xmm1 # shift right 16-r13 byte
pxor %xmm1, %xmm0 # Plaintext XOR Encrypt(K, Yn)
- movdqu ALL_F-SHIFT_MASK(%r12), %xmm1
+ movdqu (%r12), %xmm1
# get the appropriate mask to mask out top 16-r13 bytes of xmm0
pand %xmm1, %xmm0 # mask out top 16-r13 bytes of xmm0
movdqa SHUF_MASK(%rip), %xmm10
@@ -1784,9 +1790,6 @@ _zero_cipher_left_encrypt:
pxor %xmm0, %xmm8
GHASH_MUL %xmm8, %xmm13, %xmm9, %xmm10, %xmm11, %xmm5, %xmm6
# GHASH computation for the last <16 byte block
- sub %r13, %r11
- add $16, %r11
-
movdqa SHUF_MASK(%rip), %xmm10
PSHUFB_XMM %xmm10, %xmm0
--
2.15.1.620.gb9897f4670-goog
The aesni_gcm_enc/dec functions can access memory after the end of
the AAD buffer if the AAD length is not a multiple of 4 bytes.
It didn't matter with rfc4106-gcm-aesni as in that case the AAD was
always followed by the 8 byte IV, but that is no longer the case with
generic-gcm-aesni. This can potentially result in accessing a page that
is not mapped and thus causing the machine to crash. This patch fixes
that by reading the last <16 byte block of the AAD byte-by-byte and
optionally via an 8-byte load if the block was at least 8 bytes.
Fixes: 0487ccac ("crypto: aesni - make non-AVX AES-GCM work with any aadlen")
Signed-off-by: Junaid Shahid <[email protected]>
---
arch/x86/crypto/aesni-intel_asm.S | 112 ++++----------------------------------
1 file changed, 12 insertions(+), 100 deletions(-)
diff --git a/arch/x86/crypto/aesni-intel_asm.S b/arch/x86/crypto/aesni-intel_asm.S
index c36b850fdc81..76d8cd426a31 100644
--- a/arch/x86/crypto/aesni-intel_asm.S
+++ b/arch/x86/crypto/aesni-intel_asm.S
@@ -89,30 +89,6 @@ SHIFT_MASK: .octa 0x0f0e0d0c0b0a09080706050403020100
ALL_F: .octa 0xffffffffffffffffffffffffffffffff
.octa 0x00000000000000000000000000000000
-.section .rodata
-.align 16
-.type aad_shift_arr, @object
-.size aad_shift_arr, 272
-aad_shift_arr:
- .octa 0xffffffffffffffffffffffffffffffff
- .octa 0xffffffffffffffffffffffffffffff0C
- .octa 0xffffffffffffffffffffffffffff0D0C
- .octa 0xffffffffffffffffffffffffff0E0D0C
- .octa 0xffffffffffffffffffffffff0F0E0D0C
- .octa 0xffffffffffffffffffffff0C0B0A0908
- .octa 0xffffffffffffffffffff0D0C0B0A0908
- .octa 0xffffffffffffffffff0E0D0C0B0A0908
- .octa 0xffffffffffffffff0F0E0D0C0B0A0908
- .octa 0xffffffffffffff0C0B0A090807060504
- .octa 0xffffffffffff0D0C0B0A090807060504
- .octa 0xffffffffff0E0D0C0B0A090807060504
- .octa 0xffffffff0F0E0D0C0B0A090807060504
- .octa 0xffffff0C0B0A09080706050403020100
- .octa 0xffff0D0C0B0A09080706050403020100
- .octa 0xff0E0D0C0B0A09080706050403020100
- .octa 0x0F0E0D0C0B0A09080706050403020100
-
-
.text
@@ -303,62 +279,30 @@ _done_read_partial_block_\@:
XMM2 XMM3 XMM4 XMMDst TMP6 TMP7 i i_seq operation
MOVADQ SHUF_MASK(%rip), %xmm14
mov arg7, %r10 # %r10 = AAD
- mov arg8, %r12 # %r12 = aadLen
- mov %r12, %r11
+ mov arg8, %r11 # %r11 = aadLen
pxor %xmm\i, %xmm\i
pxor \XMM2, \XMM2
cmp $16, %r11
- jl _get_AAD_rest8\num_initial_blocks\operation
+ jl _get_AAD_rest\num_initial_blocks\operation
_get_AAD_blocks\num_initial_blocks\operation:
movdqu (%r10), %xmm\i
PSHUFB_XMM %xmm14, %xmm\i # byte-reflect the AAD data
pxor %xmm\i, \XMM2
GHASH_MUL \XMM2, \TMP3, \TMP1, \TMP2, \TMP4, \TMP5, \XMM1
add $16, %r10
- sub $16, %r12
sub $16, %r11
cmp $16, %r11
jge _get_AAD_blocks\num_initial_blocks\operation
movdqu \XMM2, %xmm\i
+
+ /* read the last <16B of AAD */
+_get_AAD_rest\num_initial_blocks\operation:
cmp $0, %r11
je _get_AAD_done\num_initial_blocks\operation
- pxor %xmm\i,%xmm\i
-
- /* read the last <16B of AAD. since we have at least 4B of
- data right after the AAD (the ICV, and maybe some CT), we can
- read 4B/8B blocks safely, and then get rid of the extra stuff */
-_get_AAD_rest8\num_initial_blocks\operation:
- cmp $4, %r11
- jle _get_AAD_rest4\num_initial_blocks\operation
- movq (%r10), \TMP1
- add $8, %r10
- sub $8, %r11
- pslldq $8, \TMP1
- psrldq $8, %xmm\i
- pxor \TMP1, %xmm\i
- jmp _get_AAD_rest8\num_initial_blocks\operation
-_get_AAD_rest4\num_initial_blocks\operation:
- cmp $0, %r11
- jle _get_AAD_rest0\num_initial_blocks\operation
- mov (%r10), %eax
- movq %rax, \TMP1
- add $4, %r10
- sub $4, %r10
- pslldq $12, \TMP1
- psrldq $4, %xmm\i
- pxor \TMP1, %xmm\i
-_get_AAD_rest0\num_initial_blocks\operation:
- /* finalize: shift out the extra bytes we read, and align
- left. since pslldq can only shift by an immediate, we use
- vpshufb and an array of shuffle masks */
- movq %r12, %r11
- salq $4, %r11
- movdqu aad_shift_arr(%r11), \TMP1
- PSHUFB_XMM \TMP1, %xmm\i
-_get_AAD_rest_final\num_initial_blocks\operation:
+ READ_PARTIAL_BLOCK %r10, %r11, \TMP1, %xmm\i
PSHUFB_XMM %xmm14, %xmm\i # byte-reflect the AAD data
pxor \XMM2, %xmm\i
GHASH_MUL %xmm\i, \TMP3, \TMP1, \TMP2, \TMP4, \TMP5, \XMM1
@@ -562,62 +506,30 @@ _initial_blocks_done\num_initial_blocks\operation:
XMM2 XMM3 XMM4 XMMDst TMP6 TMP7 i i_seq operation
MOVADQ SHUF_MASK(%rip), %xmm14
mov arg7, %r10 # %r10 = AAD
- mov arg8, %r12 # %r12 = aadLen
- mov %r12, %r11
+ mov arg8, %r11 # %r11 = aadLen
pxor %xmm\i, %xmm\i
pxor \XMM2, \XMM2
cmp $16, %r11
- jl _get_AAD_rest8\num_initial_blocks\operation
+ jl _get_AAD_rest\num_initial_blocks\operation
_get_AAD_blocks\num_initial_blocks\operation:
movdqu (%r10), %xmm\i
PSHUFB_XMM %xmm14, %xmm\i # byte-reflect the AAD data
pxor %xmm\i, \XMM2
GHASH_MUL \XMM2, \TMP3, \TMP1, \TMP2, \TMP4, \TMP5, \XMM1
add $16, %r10
- sub $16, %r12
sub $16, %r11
cmp $16, %r11
jge _get_AAD_blocks\num_initial_blocks\operation
movdqu \XMM2, %xmm\i
+
+ /* read the last <16B of AAD */
+_get_AAD_rest\num_initial_blocks\operation:
cmp $0, %r11
je _get_AAD_done\num_initial_blocks\operation
- pxor %xmm\i,%xmm\i
-
- /* read the last <16B of AAD. since we have at least 4B of
- data right after the AAD (the ICV, and maybe some PT), we can
- read 4B/8B blocks safely, and then get rid of the extra stuff */
-_get_AAD_rest8\num_initial_blocks\operation:
- cmp $4, %r11
- jle _get_AAD_rest4\num_initial_blocks\operation
- movq (%r10), \TMP1
- add $8, %r10
- sub $8, %r11
- pslldq $8, \TMP1
- psrldq $8, %xmm\i
- pxor \TMP1, %xmm\i
- jmp _get_AAD_rest8\num_initial_blocks\operation
-_get_AAD_rest4\num_initial_blocks\operation:
- cmp $0, %r11
- jle _get_AAD_rest0\num_initial_blocks\operation
- mov (%r10), %eax
- movq %rax, \TMP1
- add $4, %r10
- sub $4, %r10
- pslldq $12, \TMP1
- psrldq $4, %xmm\i
- pxor \TMP1, %xmm\i
-_get_AAD_rest0\num_initial_blocks\operation:
- /* finalize: shift out the extra bytes we read, and align
- left. since pslldq can only shift by an immediate, we use
- vpshufb and an array of shuffle masks */
- movq %r12, %r11
- salq $4, %r11
- movdqu aad_shift_arr(%r11), \TMP1
- PSHUFB_XMM \TMP1, %xmm\i
-_get_AAD_rest_final\num_initial_blocks\operation:
+ READ_PARTIAL_BLOCK %r10, %r11, \TMP1, %xmm\i
PSHUFB_XMM %xmm14, %xmm\i # byte-reflect the AAD data
pxor \XMM2, %xmm\i
GHASH_MUL %xmm\i, \TMP3, \TMP1, \TMP2, \TMP4, \TMP5, \XMM1
--
2.15.1.620.gb9897f4670-goog
On Wednesday, December 20, 2017 5:08:37 PM PST Junaid Shahid wrote:
> +.macro READ_PARTIAL_BLOCK DPTR DLEN XMM1 XMMDst
> + cmp $8, \DLEN
> + jl _read_lt8_\@
> + mov (\DPTR), %rax
> + MOVQ_R64_XMM %rax, \XMMDst
Just noticed that these two can be replaced with:
+ movq (\DPTR), \XMMDst
> + sub $8, \DLEN
> + jz _done_read_partial_block_\@
> + xor %eax, %eax
> +_read_next_byte_\@:
On Wed, Dec 20, 2017 at 05:08:36PM -0800, Junaid Shahid wrote:
> Changelog:
> v3:
> - Fixed a bug in READ_PARTIAL_BLOCK when used for reading the AAD
> - Some refactoring per CR feedback
All applied. Thanks.
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt