Re: [PATCH 1/1] use crc32 instead of md5 for hibernation e820 integrity check
On Thu, Apr 01, 2021 at 06:19:57PM +0200, Rafael J. Wysocki wrote:
> On Thu, Apr 1, 2021 at 3:59 PM Ard Biesheuvel wrote:
> >
> > On Thu, 1 Apr 2021 at 15:34, Rafael J. Wysocki wrote:
> > >
> > > On Thu, Apr 1, 2021 at 2:25 PM Chris von Recklinghausen
> > > wrote:
> > > >
> > > > Suspend fails on a system in fips mode because md5 is used for the e820
> > > > integrity check and is not available. Use crc32 instead.
> > > >
> > > > Fixes: 62a03defeabd ("PM / hibernate: Verify the consistent of e820
> > > > memory map
> > > >by md5 digest")
> > > > Signed-off-by: Chris von Recklinghausen
> > > > ---
> > > > arch/x86/power/hibernate.c | 31 +--
> > > > 1 file changed, 17 insertions(+), 14 deletions(-)
> > > >
> > > > diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
> > > > index cd3914fc9f3d..6a3f4e32e49c 100644
> > > > --- a/arch/x86/power/hibernate.c
> > > > +++ b/arch/x86/power/hibernate.c
> > > > @@ -55,31 +55,31 @@ int pfn_is_nosave(unsigned long pfn)
> > > > }
> > > >
> > > >
> > > > -#define MD5_DIGEST_SIZE 16
> > > > +#define CRC32_DIGEST_SIZE 16
> > > >
> > > > struct restore_data_record {
> > > > unsigned long jump_address;
> > > > unsigned long jump_address_phys;
> > > > unsigned long cr3;
> > > > unsigned long magic;
> > > > - u8 e820_digest[MD5_DIGEST_SIZE];
> > > > + u8 e820_digest[CRC32_DIGEST_SIZE];
> > > > };
> > >
> > > No.
> > >
> > > CRC32 was used here before and it was deemed insufficient.
> > >
> >
> > Why? The git commit log does not have an explanation of this.
>
> IIRC there was an example of a memory map that would produce the same
> CRC32 value as the original or something like that.
Collisions can easily be found for MD5 as well, as it is heavily broken.
Either you need a cryptographic hash function, *or* a (non-cryptographic)
checksum would be sufficient. There isn't really any in-between.
And if a checksum suffices, MD5 is a bad choice because it was designed as a
cryptographic hash function, so it is much slower than a checksum.
>
> But that said this code is all about failing more gracefully, so I
> guess it isn't a big deal if the failure is more graceful in fewer
> cases ...
If the 1 in 2^32 chance of a CRC-32 collision is too high, then use CRC-64 or
xxHash64 for a 1 in 2^64 chance of a collision.
- Eric
Re: [PATCH 1/1] use crc32 instead of md5 for hibernation e820 integrity check
On Thu, Apr 1, 2021 at 3:34 PM Rafael J. Wysocki wrote:
>
> On Thu, Apr 1, 2021 at 2:25 PM Chris von Recklinghausen
> wrote:
> >
> > Suspend fails on a system in fips mode because md5 is used for the e820
> > integrity check and is not available. Use crc32 instead.
> >
> > Fixes: 62a03defeabd ("PM / hibernate: Verify the consistent of e820 memory
> > map
> >by md5 digest")
> > Signed-off-by: Chris von Recklinghausen
> > ---
> > arch/x86/power/hibernate.c | 31 +--
> > 1 file changed, 17 insertions(+), 14 deletions(-)
> >
> > diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
> > index cd3914fc9f3d..6a3f4e32e49c 100644
> > --- a/arch/x86/power/hibernate.c
> > +++ b/arch/x86/power/hibernate.c
> > @@ -55,31 +55,31 @@ int pfn_is_nosave(unsigned long pfn)
> > }
> >
> >
> > -#define MD5_DIGEST_SIZE 16
> > +#define CRC32_DIGEST_SIZE 16
> >
> > struct restore_data_record {
> > unsigned long jump_address;
> > unsigned long jump_address_phys;
> > unsigned long cr3;
> > unsigned long magic;
> > - u8 e820_digest[MD5_DIGEST_SIZE];
> > + u8 e820_digest[CRC32_DIGEST_SIZE];
> > };
>
> No.
>
> CRC32 was used here before and it was deemed insufficient.
>
> Please find a different way to address this issue.
Well, I guess I'm going to change my mind on this, so we can go with
this patch, but please bump up RESTORE_MAGIC too.
> > -#if IS_BUILTIN(CONFIG_CRYPTO_MD5)
> > +#if IS_BUILTIN(CONFIG_CRYPTO_CRC32)
> > /**
> > - * get_e820_md5 - calculate md5 according to given e820 table
> > + * get_e820_crc32 - calculate crc32 according to given e820 table
> > *
> > * @table: the e820 table to be calculated
> > - * @buf: the md5 result to be stored to
> > + * @buf: the crc32 result to be stored to
> > */
> > -static int get_e820_md5(struct e820_table *table, void *buf)
> > +static int get_e820_crc32(struct e820_table *table, void *buf)
> > {
> > struct crypto_shash *tfm;
> > struct shash_desc *desc;
> > int size;
> > int ret = 0;
> >
> > - tfm = crypto_alloc_shash("md5", 0, 0);
> > + tfm = crypto_alloc_shash("crc32", 0, 0);
> > if (IS_ERR(tfm))
> > return -ENOMEM;
> >
> > @@ -107,24 +107,24 @@ static int get_e820_md5(struct e820_table *table,
> > void *buf)
> >
> > static int hibernation_e820_save(void *buf)
> > {
> > - return get_e820_md5(e820_table_firmware, buf);
> > + return get_e820_crc32(e820_table_firmware, buf);
> > }
> >
> > static bool hibernation_e820_mismatch(void *buf)
> > {
> > int ret;
> > - u8 result[MD5_DIGEST_SIZE];
> > + u8 result[CRC32_DIGEST_SIZE];
> >
> > - memset(result, 0, MD5_DIGEST_SIZE);
> > + memset(result, 0, CRC32_DIGEST_SIZE);
> > /* If there is no digest in suspend kernel, let it go. */
> > - if (!memcmp(result, buf, MD5_DIGEST_SIZE))
> > + if (!memcmp(result, buf, CRC32_DIGEST_SIZE))
> > return false;
> >
> > - ret = get_e820_md5(e820_table_firmware, result);
> > + ret = get_e820_crc32(e820_table_firmware, result);
> > if (ret)
> > return true;
> >
> > - return memcmp(result, buf, MD5_DIGEST_SIZE) ? true : false;
> > + return memcmp(result, buf, CRC32_DIGEST_SIZE) ? true : false;
> > }
> > #else
> > static int hibernation_e820_save(void *buf)
> > @@ -134,7 +134,7 @@ static int hibernation_e820_save(void *buf)
> >
> > static bool hibernation_e820_mismatch(void *buf)
> > {
> > - /* If md5 is not builtin for restore kernel, let it go. */
> > + /* If crc32 is not builtin for restore kernel, let it go. */
> > return false;
> > }
> > #endif
> > @@ -160,6 +160,9 @@ int arch_hibernation_header_save(void *addr, unsigned
> > int max_size)
> > rdr->jump_address = (unsigned long)restore_registers;
> > rdr->jump_address_phys = __pa_symbol(restore_registers);
> >
> > + /* crc32 digest size is 4 but digest buffer size is 16 so zero it
> > all */
> > + memset(rdr->e820_digest, 0, CRC32_DIGEST_SIZE);
> > +
> > /*
> > * The restore code fixes up CR3 and CR4 in the following sequence:
> > *
> > --
> > 2.18.1
> >
Re: [PATCH 1/1] use crc32 instead of md5 for hibernation e820 integrity check
On Thu, Apr 1, 2021 at 3:59 PM Ard Biesheuvel wrote:
>
> On Thu, 1 Apr 2021 at 15:34, Rafael J. Wysocki wrote:
> >
> > On Thu, Apr 1, 2021 at 2:25 PM Chris von Recklinghausen
> > wrote:
> > >
> > > Suspend fails on a system in fips mode because md5 is used for the e820
> > > integrity check and is not available. Use crc32 instead.
> > >
> > > Fixes: 62a03defeabd ("PM / hibernate: Verify the consistent of e820
> > > memory map
> > >by md5 digest")
> > > Signed-off-by: Chris von Recklinghausen
> > > ---
> > > arch/x86/power/hibernate.c | 31 +--
> > > 1 file changed, 17 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
> > > index cd3914fc9f3d..6a3f4e32e49c 100644
> > > --- a/arch/x86/power/hibernate.c
> > > +++ b/arch/x86/power/hibernate.c
> > > @@ -55,31 +55,31 @@ int pfn_is_nosave(unsigned long pfn)
> > > }
> > >
> > >
> > > -#define MD5_DIGEST_SIZE 16
> > > +#define CRC32_DIGEST_SIZE 16
> > >
> > > struct restore_data_record {
> > > unsigned long jump_address;
> > > unsigned long jump_address_phys;
> > > unsigned long cr3;
> > > unsigned long magic;
> > > - u8 e820_digest[MD5_DIGEST_SIZE];
> > > + u8 e820_digest[CRC32_DIGEST_SIZE];
> > > };
> >
> > No.
> >
> > CRC32 was used here before and it was deemed insufficient.
> >
>
> Why? The git commit log does not have an explanation of this.
IIRC there was an example of a memory map that would produce the same
CRC32 value as the original or something like that.
But that said this code is all about failing more gracefully, so I
guess it isn't a big deal if the failure is more graceful in fewer
cases ...
Re: [PATCH 1/1] use crc32 instead of md5 for hibernation e820 integrity check
On Thu, Apr 1, 2021 at 2:25 PM Chris von Recklinghausen
wrote:
>
> Suspend fails on a system in fips mode because md5 is used for the e820
> integrity check and is not available. Use crc32 instead.
>
> Fixes: 62a03defeabd ("PM / hibernate: Verify the consistent of e820 memory map
>by md5 digest")
> Signed-off-by: Chris von Recklinghausen
> ---
> arch/x86/power/hibernate.c | 31 +--
> 1 file changed, 17 insertions(+), 14 deletions(-)
>
> diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
> index cd3914fc9f3d..6a3f4e32e49c 100644
> --- a/arch/x86/power/hibernate.c
> +++ b/arch/x86/power/hibernate.c
> @@ -55,31 +55,31 @@ int pfn_is_nosave(unsigned long pfn)
> }
>
>
> -#define MD5_DIGEST_SIZE 16
> +#define CRC32_DIGEST_SIZE 16
>
> struct restore_data_record {
> unsigned long jump_address;
> unsigned long jump_address_phys;
> unsigned long cr3;
> unsigned long magic;
> - u8 e820_digest[MD5_DIGEST_SIZE];
> + u8 e820_digest[CRC32_DIGEST_SIZE];
> };
No.
CRC32 was used here before and it was deemed insufficient.
Please find a different way to address this issue.
> -#if IS_BUILTIN(CONFIG_CRYPTO_MD5)
> +#if IS_BUILTIN(CONFIG_CRYPTO_CRC32)
> /**
> - * get_e820_md5 - calculate md5 according to given e820 table
> + * get_e820_crc32 - calculate crc32 according to given e820 table
> *
> * @table: the e820 table to be calculated
> - * @buf: the md5 result to be stored to
> + * @buf: the crc32 result to be stored to
> */
> -static int get_e820_md5(struct e820_table *table, void *buf)
> +static int get_e820_crc32(struct e820_table *table, void *buf)
> {
> struct crypto_shash *tfm;
> struct shash_desc *desc;
> int size;
> int ret = 0;
>
> - tfm = crypto_alloc_shash("md5", 0, 0);
> + tfm = crypto_alloc_shash("crc32", 0, 0);
> if (IS_ERR(tfm))
> return -ENOMEM;
>
> @@ -107,24 +107,24 @@ static int get_e820_md5(struct e820_table *table, void
> *buf)
>
> static int hibernation_e820_save(void *buf)
> {
> - return get_e820_md5(e820_table_firmware, buf);
> + return get_e820_crc32(e820_table_firmware, buf);
> }
>
> static bool hibernation_e820_mismatch(void *buf)
> {
> int ret;
> - u8 result[MD5_DIGEST_SIZE];
> + u8 result[CRC32_DIGEST_SIZE];
>
> - memset(result, 0, MD5_DIGEST_SIZE);
> + memset(result, 0, CRC32_DIGEST_SIZE);
> /* If there is no digest in suspend kernel, let it go. */
> - if (!memcmp(result, buf, MD5_DIGEST_SIZE))
> + if (!memcmp(result, buf, CRC32_DIGEST_SIZE))
> return false;
>
> - ret = get_e820_md5(e820_table_firmware, result);
> + ret = get_e820_crc32(e820_table_firmware, result);
> if (ret)
> return true;
>
> - return memcmp(result, buf, MD5_DIGEST_SIZE) ? true : false;
> + return memcmp(result, buf, CRC32_DIGEST_SIZE) ? true : false;
> }
> #else
> static int hibernation_e820_save(void *buf)
> @@ -134,7 +134,7 @@ static int hibernation_e820_save(void *buf)
>
> static bool hibernation_e820_mismatch(void *buf)
> {
> - /* If md5 is not builtin for restore kernel, let it go. */
> + /* If crc32 is not builtin for restore kernel, let it go. */
> return false;
> }
> #endif
> @@ -160,6 +160,9 @@ int arch_hibernation_header_save(void *addr, unsigned int
> max_size)
> rdr->jump_address = (unsigned long)restore_registers;
> rdr->jump_address_phys = __pa_symbol(restore_registers);
>
> + /* crc32 digest size is 4 but digest buffer size is 16 so zero it all
> */
> + memset(rdr->e820_digest, 0, CRC32_DIGEST_SIZE);
> +
> /*
> * The restore code fixes up CR3 and CR4 in the following sequence:
> *
> --
> 2.18.1
>
[PATCH 1/1] use crc32 instead of md5 for hibernation e820 integrity check
Suspend fails on a system in fips mode because md5 is used for the e820
integrity check and is not available. Use crc32 instead.
Fixes: 62a03defeabd ("PM / hibernate: Verify the consistent of e820 memory map
by md5 digest")
Signed-off-by: Chris von Recklinghausen
---
arch/x86/power/hibernate.c | 31 +--
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
index cd3914fc9f3d..6a3f4e32e49c 100644
--- a/arch/x86/power/hibernate.c
+++ b/arch/x86/power/hibernate.c
@@ -55,31 +55,31 @@ int pfn_is_nosave(unsigned long pfn)
}
-#define MD5_DIGEST_SIZE 16
+#define CRC32_DIGEST_SIZE 16
struct restore_data_record {
unsigned long jump_address;
unsigned long jump_address_phys;
unsigned long cr3;
unsigned long magic;
- u8 e820_digest[MD5_DIGEST_SIZE];
+ u8 e820_digest[CRC32_DIGEST_SIZE];
};
-#if IS_BUILTIN(CONFIG_CRYPTO_MD5)
+#if IS_BUILTIN(CONFIG_CRYPTO_CRC32)
/**
- * get_e820_md5 - calculate md5 according to given e820 table
+ * get_e820_crc32 - calculate crc32 according to given e820 table
*
* @table: the e820 table to be calculated
- * @buf: the md5 result to be stored to
+ * @buf: the crc32 result to be stored to
*/
-static int get_e820_md5(struct e820_table *table, void *buf)
+static int get_e820_crc32(struct e820_table *table, void *buf)
{
struct crypto_shash *tfm;
struct shash_desc *desc;
int size;
int ret = 0;
- tfm = crypto_alloc_shash("md5", 0, 0);
+ tfm = crypto_alloc_shash("crc32", 0, 0);
if (IS_ERR(tfm))
return -ENOMEM;
@@ -107,24 +107,24 @@ static int get_e820_md5(struct e820_table *table, void
*buf)
static int hibernation_e820_save(void *buf)
{
- return get_e820_md5(e820_table_firmware, buf);
+ return get_e820_crc32(e820_table_firmware, buf);
}
static bool hibernation_e820_mismatch(void *buf)
{
int ret;
- u8 result[MD5_DIGEST_SIZE];
+ u8 result[CRC32_DIGEST_SIZE];
- memset(result, 0, MD5_DIGEST_SIZE);
+ memset(result, 0, CRC32_DIGEST_SIZE);
/* If there is no digest in suspend kernel, let it go. */
- if (!memcmp(result, buf, MD5_DIGEST_SIZE))
+ if (!memcmp(result, buf, CRC32_DIGEST_SIZE))
return false;
- ret = get_e820_md5(e820_table_firmware, result);
+ ret = get_e820_crc32(e820_table_firmware, result);
if (ret)
return true;
- return memcmp(result, buf, MD5_DIGEST_SIZE) ? true : false;
+ return memcmp(result, buf, CRC32_DIGEST_SIZE) ? true : false;
}
#else
static int hibernation_e820_save(void *buf)
@@ -134,7 +134,7 @@ static int hibernation_e820_save(void *buf)
static bool hibernation_e820_mismatch(void *buf)
{
- /* If md5 is not builtin for restore kernel, let it go. */
+ /* If crc32 is not builtin for restore kernel, let it go. */
return false;
}
#endif
@@ -160,6 +160,9 @@ int arch_hibernation_header_save(void *addr, unsigned int
max_size)
rdr->jump_address = (unsigned long)restore_registers;
rdr->jump_address_phys = __pa_symbol(restore_registers);
+ /* crc32 digest size is 4 but digest buffer size is 16 so zero it all */
+ memset(rdr->e820_digest, 0, CRC32_DIGEST_SIZE);
+
/*
* The restore code fixes up CR3 and CR4 in the following sequence:
*
--
2.18.1
Re: [PATCH 1/1] use crc32 instead of md5 for hibernation e820 integrity check
On Thu, 1 Apr 2021 at 15:34, Rafael J. Wysocki wrote:
>
> On Thu, Apr 1, 2021 at 2:25 PM Chris von Recklinghausen
> wrote:
> >
> > Suspend fails on a system in fips mode because md5 is used for the e820
> > integrity check and is not available. Use crc32 instead.
> >
> > Fixes: 62a03defeabd ("PM / hibernate: Verify the consistent of e820 memory
> > map
> >by md5 digest")
> > Signed-off-by: Chris von Recklinghausen
> > ---
> > arch/x86/power/hibernate.c | 31 +--
> > 1 file changed, 17 insertions(+), 14 deletions(-)
> >
> > diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
> > index cd3914fc9f3d..6a3f4e32e49c 100644
> > --- a/arch/x86/power/hibernate.c
> > +++ b/arch/x86/power/hibernate.c
> > @@ -55,31 +55,31 @@ int pfn_is_nosave(unsigned long pfn)
> > }
> >
> >
> > -#define MD5_DIGEST_SIZE 16
> > +#define CRC32_DIGEST_SIZE 16
> >
> > struct restore_data_record {
> > unsigned long jump_address;
> > unsigned long jump_address_phys;
> > unsigned long cr3;
> > unsigned long magic;
> > - u8 e820_digest[MD5_DIGEST_SIZE];
> > + u8 e820_digest[CRC32_DIGEST_SIZE];
> > };
>
> No.
>
> CRC32 was used here before and it was deemed insufficient.
>
Why? The git commit log does not have an explanation of this.
> Please find a different way to address this issue.
>
> > -#if IS_BUILTIN(CONFIG_CRYPTO_MD5)
> > +#if IS_BUILTIN(CONFIG_CRYPTO_CRC32)
> > /**
> > - * get_e820_md5 - calculate md5 according to given e820 table
> > + * get_e820_crc32 - calculate crc32 according to given e820 table
> > *
> > * @table: the e820 table to be calculated
> > - * @buf: the md5 result to be stored to
> > + * @buf: the crc32 result to be stored to
> > */
> > -static int get_e820_md5(struct e820_table *table, void *buf)
> > +static int get_e820_crc32(struct e820_table *table, void *buf)
> > {
> > struct crypto_shash *tfm;
> > struct shash_desc *desc;
> > int size;
> > int ret = 0;
> >
> > - tfm = crypto_alloc_shash("md5", 0, 0);
> > + tfm = crypto_alloc_shash("crc32", 0, 0);
> > if (IS_ERR(tfm))
> > return -ENOMEM;
> >
> > @@ -107,24 +107,24 @@ static int get_e820_md5(struct e820_table *table,
> > void *buf)
> >
> > static int hibernation_e820_save(void *buf)
> > {
> > - return get_e820_md5(e820_table_firmware, buf);
> > + return get_e820_crc32(e820_table_firmware, buf);
> > }
> >
> > static bool hibernation_e820_mismatch(void *buf)
> > {
> > int ret;
> > - u8 result[MD5_DIGEST_SIZE];
> > + u8 result[CRC32_DIGEST_SIZE];
> >
> > - memset(result, 0, MD5_DIGEST_SIZE);
> > + memset(result, 0, CRC32_DIGEST_SIZE);
> > /* If there is no digest in suspend kernel, let it go. */
> > - if (!memcmp(result, buf, MD5_DIGEST_SIZE))
> > + if (!memcmp(result, buf, CRC32_DIGEST_SIZE))
> > return false;
> >
> > - ret = get_e820_md5(e820_table_firmware, result);
> > + ret = get_e820_crc32(e820_table_firmware, result);
> > if (ret)
> > return true;
> >
> > - return memcmp(result, buf, MD5_DIGEST_SIZE) ? true : false;
> > + return memcmp(result, buf, CRC32_DIGEST_SIZE) ? true : false;
> > }
> > #else
> > static int hibernation_e820_save(void *buf)
> > @@ -134,7 +134,7 @@ static int hibernation_e820_save(void *buf)
> >
> > static bool hibernation_e820_mismatch(void *buf)
> > {
> > - /* If md5 is not builtin for restore kernel, let it go. */
> > + /* If crc32 is not builtin for restore kernel, let it go. */
> > return false;
> > }
> > #endif
> > @@ -160,6 +160,9 @@ int arch_hibernation_header_save(void *addr, unsigned
> > int max_size)
> > rdr->jump_address = (unsigned long)restore_registers;
> > rdr->jump_address_phys = __pa_symbol(restore_registers);
> >
> > + /* crc32 digest size is 4 but digest buffer size is 16 so zero it
> > all */
> > + memset(rdr->e820_digest, 0, CRC32_DIGEST_SIZE);
> > +
> > /*
> > * The restore code fixes up CR3 and CR4 in the following sequence:
> > *
> > --
> > 2.18.1
> >
