2009-09-04 04:52:47

by Jason Gunthorpe

[permalink] [raw]
Subject: [PATCH] TPM: Fixup pubek sysfs file

tpm_show_pubek is utterly and completely wrong, all the offsets
into the binary blob are wrong, the output is garbage. Do it again.

Before:
Algorithm: 00 0C 00 00
Encscheme: 08 00
Sigscheme: 00 00
Parameters: 00 00 00 00 01 00 AF 6B 30 9B 0D B3
Modulus length: -1266846667
Modulus:
68 45 8D CA A5 EF A8 8A DD 0F D7 84 8E 8D 1F 40
22 92 09 CF 12 C8 9F 6E 55 57 6A 2C A8 0B 5E 45
C7 5E 3D 56 DA 64 E6 E1 F7 8C DD 41 92 28 2E 06
41 02 3E 11 7D B2 C5 46 38 E5 8C 60 D2 96 EE 0C
D6 3D F8 99 E3 02 3A 32 7A 02 C8 31 29 98 28 B9
1B EF 30 A1 A0 45 A0 C0 05 0E C5 96 95 FD 91 47
0A 35 E0 69 B0 8B 49 BD B9 F6 5D 25 21 25 79 1B
20 0D C3 C7 1F 87 5E 5F 41 4B DE 32 DF 55 F3 BD
7F CA D8 7D 3A B4 D5 0A EF CF 8E 72 20 52 15 FA
FB C6 C0 2E C2 AB C6 07 D0 9D 96 6B 2E 30 F7 54
C4 A5 CD 9B 13 54 A0 D1 71 66 91 97 06 12 B5 2D
B2 33 62 FB 56 62 64 A8 AA E9 F2 F4 03 C3 F4 49
2A 09 0D 7D 75 99 6C F0 47 1E 7D D5 A5 CA CE EF
45 B2 DA 88 93 B4 EE EB FB B0 A6 A4 19 C4 B8 0D
04 46 AE BD C5 2E 30 84 49 57 25 34 78 E6 ED C4
50 AF 3B F6 86 43 54 0A D9 DB 54 9C 06 B3 50 7F

After:
Algorithm: 00 00 00 01
Encscheme: 00 03
Sigscheme: 00 01
Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
Modulus length: 256
Modulus:
AF 6B 30 9B 0D B3 B4 7D 74 35 68 45 8D CA A5 EF
A8 8A DD 0F D7 84 8E 8D 1F 40 22 92 09 CF 12 C8
9F 6E 55 57 6A 2C A8 0B 5E 45 C7 5E 3D 56 DA 64
E6 E1 F7 8C DD 41 92 28 2E 06 41 02 3E 11 7D B2
C5 46 38 E5 8C 60 D2 96 EE 0C D6 3D F8 99 E3 02
3A 32 7A 02 C8 31 29 98 28 B9 1B EF 30 A1 A0 45
A0 C0 05 0E C5 96 95 FD 91 47 0A 35 E0 69 B0 8B
49 BD B9 F6 5D 25 21 25 79 1B 20 0D C3 C7 1F 87
5E 5F 41 4B DE 32 DF 55 F3 BD 7F CA D8 7D 3A B4
D5 0A EF CF 8E 72 20 52 15 FA FB C6 C0 2E C2 AB
C6 07 D0 9D 96 6B 2E 30 F7 54 C4 A5 CD 9B 13 54
A0 D1 71 66 91 97 06 12 B5 2D B2 33 62 FB 56 62
64 A8 AA E9 F2 F4 03 C3 F4 49 2A 09 0D 7D 75 99
6C F0 47 1E 7D D5 A5 CA CE EF 45 B2 DA 88 93 B4
EE EB FB B0 A6 A4 19 C4 B8 0D 04 46 AE BD C5 2E
30 84 49 57 25 34 78 E6 ED C4 50 AF 3B F6 86 43

I've checked this decoded output in two different ways.

Tested on a winbond WPCT200

Signed-off-by: Jason Gunthorpe <[email protected]>
---
drivers/char/tpm/tpm.c | 77 +++++++++++++++++++++++++++++++++---------------
1 files changed, 53 insertions(+), 24 deletions(-)

Andrew: More testing found this too. In truth this file is probably
fairly useless since it won't output anything once the TPM is owned,
but if it is going to be there it may as well work right.

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 5d5b324..196bc48 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -460,6 +460,11 @@ static ssize_t transmit_cmd(struct tpm_chip *chip, struct tpm_cmd_t *cmd,
dev_dbg(chip->dev, "A TPM error (%d) occurred %s\n", err, desc);
return err;
}
+ if (len != be32_to_cpu(cmd->header.out.length)) {
+ dev_dbg(chip->dev, "TPM returned the wrong length %x %x\n",
+ len, be32_to_cpu(cmd->header.out.length));
+ return -1;
+ }
return 0;
}

@@ -811,43 +816,67 @@ ssize_t tpm_show_pubek(struct device *dev, struct device_attribute *attr,
{
u8 *data;
struct tpm_cmd_t tpm_cmd;
- ssize_t err;
- int i, rc;
+ ssize_t len;
+ int i, rc, key_len;
char *str = buf;

struct tpm_chip *chip = dev_get_drvdata(dev);

tpm_cmd.header.in = tpm_readpubek_header;
- err = transmit_cmd(chip, &tpm_cmd, READ_PUBEK_RESULT_SIZE,
- "attempting to read the PUBEK");
- if (err)
+ if (transmit_cmd(chip, &tpm_cmd, READ_PUBEK_RESULT_SIZE,
+ "attempting to read the PUBEK"))
+ goto out;
+
+ len = be32_to_cpu(tpm_cmd.header.out.length);
+ if (len <= 0)
goto out;

- /*
- ignore header 10 bytes
- algorithm 32 bits (1 == RSA )
- encscheme 16 bits
- sigscheme 16 bits
- parameters (RSA 12->bytes: keybit, #primes, expbit)
- keylenbytes 32 bits
- 256 byte modulus
- ignore checksum 20 bytes
+ /* Format (in bytes):
+ 10 RPC Header (tpm_cmd.header)
+ xx TPM_PUBKEY pubEK
+ xx TPM_KEY_PARMS
+ 4 algorithmID
+ 2 encScheme
+ 2 sigcScheme
+ 4 parmSize
+ xx parms (typically 12 bytes for a RSA key)
+ xx TPM_STORE_PUBKEY
+ 4 keyLength
+ xx key (typically 256 for a RSA key)
+ 20 TPM_DIGEST checksum
*/
data = tpm_cmd.params.readpubek_out_buffer;
+ len -= 10;
+ if (len < 24)
+ goto out;
str +=
sprintf(str,
"Algorithm: %02X %02X %02X %02X\nEncscheme: %02X %02X\n"
"Sigscheme: %02X %02X\nParameters: %02X %02X %02X %02X"
- " %02X %02X %02X %02X %02X %02X %02X %02X\n"
- "Modulus length: %d\nModulus: \n",
- data[10], data[11], data[12], data[13], data[14],
- data[15], data[16], data[17], data[22], data[23],
- data[24], data[25], data[26], data[27], data[28],
- data[29], data[30], data[31], data[32], data[33],
- be32_to_cpu(*((__be32 *) (data + 34))));
-
- for (i = 0; i < 256; i++) {
- str += sprintf(str, "%02X ", data[i + 38]);
+ " %02X %02X %02X %02X %02X %02X %02X %02X\n",
+ data[0], data[1], data[2], data[3],
+ data[4], data[5],
+ data[6], data[7],
+ data[12], data[13], data[14], data[15], data[16], data[17],
+ data[18], data[19], data[20], data[21], data[22], data[23]);
+ /* Skip TPM_KEY_PARMS.parms and TPM_STORE_PBUKEY.keyLength */
+ i = 4 + 2 + 2 + 4 + be32_to_cpu(*((__be32 *) (data + 8))) + 4;
+ if (i > len)
+ goto out;
+ data += i;
+ len -= i;
+ key_len = be32_to_cpu(*((__be32 *) (data) - 1));
+
+ /* Note: The value printed here is the TPM_STORE_PUBKEY. For RSA keys
+ this is a modulus, but it can vary for other key types. */
+ str += sprintf(str, "Modulus length: %d\nModulus: \n", key_len);
+
+ /* len is bounded, so key_len is bounded, so sprintf is bounded, so
+ str doesn't overflow. Well, maybe. */
+ if (key_len > len)
+ goto out;
+ for (i = 0; i < key_len; i++) {
+ str += sprintf(str, "%02X ", data[i]);
if ((i + 1) % 16 == 0)
str += sprintf(str, "\n");
}
--
1.5.4.2


2009-09-04 05:02:23

by Roland Dreier

[permalink] [raw]
Subject: Re: [PATCH] TPM: Fixup pubek sysfs file


> Algorithm: 00 00 00 01
> Encscheme: 00 03
> Sigscheme: 00 01
> Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
> Modulus length: 256

No argument that this fix is an improvement, but what happened to the
"one value per file" rule for sysfs??

- R.

2009-09-04 21:05:24

by Andrew Morton

[permalink] [raw]
Subject: Re: [PATCH] TPM: Fixup pubek sysfs file

On Thu, 03 Sep 2009 22:02:24 -0700
Roland Dreier <[email protected]> wrote:

>
> > Algorithm: 00 00 00 01
> > Encscheme: 00 03
> > Sigscheme: 00 01
> > Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
> > Modulus length: 256
>
> No argument that this fix is an improvement, but what happened to the
> "one value per file" rule for sysfs??

We goofed. This one snuck through.

It's one of the reasons why I recommend that people cite examples of
the sysfs/procfs output in changelogs. These things are part of the
kernel ABI and once they go in we cannot change them so we have to get
them right first time.

2009-09-04 21:23:35

by Jason Gunthorpe

[permalink] [raw]
Subject: Re: [PATCH] TPM: Fixup pubek sysfs file

On Fri, Sep 04, 2009 at 02:03:25PM -0700, Andrew Morton wrote:
> On Thu, 03 Sep 2009 22:02:24 -0700
> Roland Dreier <[email protected]> wrote:
>
> >
> > > Algorithm: 00 00 00 01
> > > Encscheme: 00 03
> > > Sigscheme: 00 01
> > > Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
> > > Modulus length: 256
> >
> > No argument that this fix is an improvement, but what happened to the
> > "one value per file" rule for sysfs??
>
> We goofed. This one snuck through.
>
> It's one of the reasons why I recommend that people cite examples of
> the sysfs/procfs output in changelogs. These things are part of the
> kernel ABI and once they go in we cannot change them so we have to get
> them right first time.

Several of the sysfs files in the TPM driver are goofed:

/sys/devices/platform/tpm_tis.0 # cat caps
Manufacturer: 0x57454300
TCG version: 1.2
Firmware version: 2.16

/sys/devices/platform/tpm_tis.0 # cat pcrs
PCR-00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-01: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-02: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-03: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-04: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-05: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-06: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-07: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-08: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-09: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-11: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-12: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-13: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-14: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-15: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-16: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
PCR-17: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
PCR-18: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
PCR-19: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
PCR-20: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
PCR-21: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
PCR-22: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
PCR-23: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

/sys/devices/platform/tpm_tis.0 # cat pubek
Algorithm: 00 00 00 01
Encscheme: 00 03
Sigscheme: 00 01
Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
Modulus length: 256
Modulus:
AF 6B 30 9B 0D B3 B4 7D 74 35 68 45 8D CA A5 EF
A8 8A DD 0F D7 84 8E 8D 1F 40 22 92 09 CF 12 C8
9F 6E 55 57 6A 2C A8 0B 5E 45 C7 5E 3D 56 DA 64
E6 E1 F7 8C DD 41 92 28 2E 06 41 02 3E 11 7D B2
C5 46 38 E5 8C 60 D2 96 EE 0C D6 3D F8 99 E3 02
3A 32 7A 02 C8 31 29 98 28 B9 1B EF 30 A1 A0 45
A0 C0 05 0E C5 96 95 FD 91 47 0A 35 E0 69 B0 8B
49 BD B9 F6 5D 25 21 25 79 1B 20 0D C3 C7 1F 87
5E 5F 41 4B DE 32 DF 55 F3 BD 7F CA D8 7D 3A B4
D5 0A EF CF 8E 72 20 52 15 FA FB C6 C0 2E C2 AB
C6 07 D0 9D 96 6B 2E 30 F7 54 C4 A5 CD 9B 13 54
A0 D1 71 66 91 97 06 12 B5 2D B2 33 62 FB 56 62
64 A8 AA E9 F2 F4 03 C3 F4 49 2A 09 0D 7D 75 99
6C F0 47 1E 7D D5 A5 CA CE EF 45 B2 DA 88 93 B4
EE EB FB B0 A6 A4 19 C4 B8 0D 04 46 AE BD C5 2E
30 84 49 57 25 34 78 E6 ED C4 50 AF 3B F6 86 43

At least this has been like this since before the git history, so it
isn't recent..

Can these be scheduled for removal or some such process? I haven't
seen anything actually using the files, the only one that is really
useful is caps...

They probably should have been in debugfs, had it existed at the time.

Thanks,
Jason

2009-09-11 16:31:30

by Greg KH

[permalink] [raw]
Subject: Re: [PATCH] TPM: Fixup pubek sysfs file

On Fri, Sep 04, 2009 at 02:03:25PM -0700, Andrew Morton wrote:
> On Thu, 03 Sep 2009 22:02:24 -0700
> Roland Dreier <[email protected]> wrote:
>
> >
> > > Algorithm: 00 00 00 01
> > > Encscheme: 00 03
> > > Sigscheme: 00 01
> > > Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
> > > Modulus length: 256
> >
> > No argument that this fix is an improvement, but what happened to the
> > "one value per file" rule for sysfs??
>
> We goofed. This one snuck through.
>
> It's one of the reasons why I recommend that people cite examples of
> the sysfs/procfs output in changelogs. These things are part of the
> kernel ABI and once they go in we cannot change them so we have to get
> them right first time.

Also, I try to ask for a Documentation/ABI/ update for every new sysfs
file that is added. That will show this kind of thing quite easily.

thanks,

greg k-h

2009-09-11 16:31:39

by Greg KH

[permalink] [raw]
Subject: Re: [PATCH] TPM: Fixup pubek sysfs file

On Fri, Sep 04, 2009 at 03:23:16PM -0600, Jason Gunthorpe wrote:
> On Fri, Sep 04, 2009 at 02:03:25PM -0700, Andrew Morton wrote:
> > On Thu, 03 Sep 2009 22:02:24 -0700
> > Roland Dreier <[email protected]> wrote:
> >
> > >
> > > > Algorithm: 00 00 00 01
> > > > Encscheme: 00 03
> > > > Sigscheme: 00 01
> > > > Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
> > > > Modulus length: 256
> > >
> > > No argument that this fix is an improvement, but what happened to the
> > > "one value per file" rule for sysfs??
> >
> > We goofed. This one snuck through.
> >
> > It's one of the reasons why I recommend that people cite examples of
> > the sysfs/procfs output in changelogs. These things are part of the
> > kernel ABI and once they go in we cannot change them so we have to get
> > them right first time.
>
> Several of the sysfs files in the TPM driver are goofed:
>
> /sys/devices/platform/tpm_tis.0 # cat caps
> Manufacturer: 0x57454300
> TCG version: 1.2
> Firmware version: 2.16
>
> /sys/devices/platform/tpm_tis.0 # cat pcrs
> PCR-00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-01: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-02: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-03: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-04: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-05: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-06: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-07: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-08: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-09: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-11: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-12: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-13: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-14: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-15: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-16: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> PCR-17: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
> PCR-18: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
> PCR-19: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
> PCR-20: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
> PCR-21: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
> PCR-22: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
> PCR-23: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>
> /sys/devices/platform/tpm_tis.0 # cat pubek
> Algorithm: 00 00 00 01
> Encscheme: 00 03
> Sigscheme: 00 01
> Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
> Modulus length: 256
> Modulus:
> AF 6B 30 9B 0D B3 B4 7D 74 35 68 45 8D CA A5 EF
> A8 8A DD 0F D7 84 8E 8D 1F 40 22 92 09 CF 12 C8
> 9F 6E 55 57 6A 2C A8 0B 5E 45 C7 5E 3D 56 DA 64
> E6 E1 F7 8C DD 41 92 28 2E 06 41 02 3E 11 7D B2
> C5 46 38 E5 8C 60 D2 96 EE 0C D6 3D F8 99 E3 02
> 3A 32 7A 02 C8 31 29 98 28 B9 1B EF 30 A1 A0 45
> A0 C0 05 0E C5 96 95 FD 91 47 0A 35 E0 69 B0 8B
> 49 BD B9 F6 5D 25 21 25 79 1B 20 0D C3 C7 1F 87
> 5E 5F 41 4B DE 32 DF 55 F3 BD 7F CA D8 7D 3A B4
> D5 0A EF CF 8E 72 20 52 15 FA FB C6 C0 2E C2 AB
> C6 07 D0 9D 96 6B 2E 30 F7 54 C4 A5 CD 9B 13 54
> A0 D1 71 66 91 97 06 12 B5 2D B2 33 62 FB 56 62
> 64 A8 AA E9 F2 F4 03 C3 F4 49 2A 09 0D 7D 75 99
> 6C F0 47 1E 7D D5 A5 CA CE EF 45 B2 DA 88 93 B4
> EE EB FB B0 A6 A4 19 C4 B8 0D 04 46 AE BD C5 2E
> 30 84 49 57 25 34 78 E6 ED C4 50 AF 3B F6 86 43
>
> At least this has been like this since before the git history, so it
> isn't recent..
>
> Can these be scheduled for removal or some such process? I haven't
> seen anything actually using the files, the only one that is really
> useful is caps...
>
> They probably should have been in debugfs, had it existed at the time.

Feel free to move them to debugfs, it looks like that is what they are
for.

thanks,

greg k-h

2009-09-14 20:49:11

by Rajiv Andrade

[permalink] [raw]
Subject: Re: [PATCH] TPM: Fixup pubek sysfs file

I was about to suggest including some #defines here but the comment
section explaining the format already documents the offsets.

Thanks

Reviewed-by: Rajiv Andrade <[email protected]>

On Thu, 2009-09-03 at 22:52 -0600, Jason Gunthorpe wrote:
> tpm_show_pubek is utterly and completely wrong, all the offsets
> into the binary blob are wrong, the output is garbage. Do it again.
>
> Before:
> Algorithm: 00 0C 00 00
> Encscheme: 08 00
> Sigscheme: 00 00
> Parameters: 00 00 00 00 01 00 AF 6B 30 9B 0D B3
> Modulus length: -1266846667
> Modulus:
> 68 45 8D CA A5 EF A8 8A DD 0F D7 84 8E 8D 1F 40
> 22 92 09 CF 12 C8 9F 6E 55 57 6A 2C A8 0B 5E 45
> C7 5E 3D 56 DA 64 E6 E1 F7 8C DD 41 92 28 2E 06
> 41 02 3E 11 7D B2 C5 46 38 E5 8C 60 D2 96 EE 0C
> D6 3D F8 99 E3 02 3A 32 7A 02 C8 31 29 98 28 B9
> 1B EF 30 A1 A0 45 A0 C0 05 0E C5 96 95 FD 91 47
> 0A 35 E0 69 B0 8B 49 BD B9 F6 5D 25 21 25 79 1B
> 20 0D C3 C7 1F 87 5E 5F 41 4B DE 32 DF 55 F3 BD
> 7F CA D8 7D 3A B4 D5 0A EF CF 8E 72 20 52 15 FA
> FB C6 C0 2E C2 AB C6 07 D0 9D 96 6B 2E 30 F7 54
> C4 A5 CD 9B 13 54 A0 D1 71 66 91 97 06 12 B5 2D
> B2 33 62 FB 56 62 64 A8 AA E9 F2 F4 03 C3 F4 49
> 2A 09 0D 7D 75 99 6C F0 47 1E 7D D5 A5 CA CE EF
> 45 B2 DA 88 93 B4 EE EB FB B0 A6 A4 19 C4 B8 0D
> 04 46 AE BD C5 2E 30 84 49 57 25 34 78 E6 ED C4
> 50 AF 3B F6 86 43 54 0A D9 DB 54 9C 06 B3 50 7F
>
> After:
> Algorithm: 00 00 00 01
> Encscheme: 00 03
> Sigscheme: 00 01
> Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
> Modulus length: 256
> Modulus:
> AF 6B 30 9B 0D B3 B4 7D 74 35 68 45 8D CA A5 EF
> A8 8A DD 0F D7 84 8E 8D 1F 40 22 92 09 CF 12 C8
> 9F 6E 55 57 6A 2C A8 0B 5E 45 C7 5E 3D 56 DA 64
> E6 E1 F7 8C DD 41 92 28 2E 06 41 02 3E 11 7D B2
> C5 46 38 E5 8C 60 D2 96 EE 0C D6 3D F8 99 E3 02
> 3A 32 7A 02 C8 31 29 98 28 B9 1B EF 30 A1 A0 45
> A0 C0 05 0E C5 96 95 FD 91 47 0A 35 E0 69 B0 8B
> 49 BD B9 F6 5D 25 21 25 79 1B 20 0D C3 C7 1F 87
> 5E 5F 41 4B DE 32 DF 55 F3 BD 7F CA D8 7D 3A B4
> D5 0A EF CF 8E 72 20 52 15 FA FB C6 C0 2E C2 AB
> C6 07 D0 9D 96 6B 2E 30 F7 54 C4 A5 CD 9B 13 54
> A0 D1 71 66 91 97 06 12 B5 2D B2 33 62 FB 56 62
> 64 A8 AA E9 F2 F4 03 C3 F4 49 2A 09 0D 7D 75 99
> 6C F0 47 1E 7D D5 A5 CA CE EF 45 B2 DA 88 93 B4
> EE EB FB B0 A6 A4 19 C4 B8 0D 04 46 AE BD C5 2E
> 30 84 49 57 25 34 78 E6 ED C4 50 AF 3B F6 86 43
>
> I've checked this decoded output in two different ways.
>
> Tested on a winbond WPCT200
>
> Signed-off-by: Jason Gunthorpe <[email protected]>
> ---
> drivers/char/tpm/tpm.c | 77 +++++++++++++++++++++++++++++++++---------------
> 1 files changed, 53 insertions(+), 24 deletions(-)
>
> Andrew: More testing found this too. In truth this file is probably
> fairly useless since it won't output anything once the TPM is owned,
> but if it is going to be there it may as well work right.
>
> diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
> index 5d5b324..196bc48 100644
> --- a/drivers/char/tpm/tpm.c
> +++ b/drivers/char/tpm/tpm.c
> @@ -460,6 +460,11 @@ static ssize_t transmit_cmd(struct tpm_chip *chip, struct tpm_cmd_t *cmd,
> dev_dbg(chip->dev, "A TPM error (%d) occurred %s\n", err, desc);
> return err;
> }
> + if (len != be32_to_cpu(cmd->header.out.length)) {
> + dev_dbg(chip->dev, "TPM returned the wrong length %x %x\n",
> + len, be32_to_cpu(cmd->header.out.length));
> + return -1;
> + }
> return 0;
> }
>
> @@ -811,43 +816,67 @@ ssize_t tpm_show_pubek(struct device *dev, struct device_attribute *attr,
> {
> u8 *data;
> struct tpm_cmd_t tpm_cmd;
> - ssize_t err;
> - int i, rc;
> + ssize_t len;
> + int i, rc, key_len;
> char *str = buf;
>
> struct tpm_chip *chip = dev_get_drvdata(dev);
>
> tpm_cmd.header.in = tpm_readpubek_header;
> - err = transmit_cmd(chip, &tpm_cmd, READ_PUBEK_RESULT_SIZE,
> - "attempting to read the PUBEK");
> - if (err)
> + if (transmit_cmd(chip, &tpm_cmd, READ_PUBEK_RESULT_SIZE,
> + "attempting to read the PUBEK"))
> + goto out;
> +
> + len = be32_to_cpu(tpm_cmd.header.out.length);
> + if (len <= 0)
> goto out;
>
> - /*
> - ignore header 10 bytes
> - algorithm 32 bits (1 == RSA )
> - encscheme 16 bits
> - sigscheme 16 bits
> - parameters (RSA 12->bytes: keybit, #primes, expbit)
> - keylenbytes 32 bits
> - 256 byte modulus
> - ignore checksum 20 bytes
> + /* Format (in bytes):
> + 10 RPC Header (tpm_cmd.header)
> + xx TPM_PUBKEY pubEK
> + xx TPM_KEY_PARMS
> + 4 algorithmID
> + 2 encScheme
> + 2 sigcScheme
> + 4 parmSize
> + xx parms (typically 12 bytes for a RSA key)
> + xx TPM_STORE_PUBKEY
> + 4 keyLength
> + xx key (typically 256 for a RSA key)
> + 20 TPM_DIGEST checksum
> */
> data = tpm_cmd.params.readpubek_out_buffer;
> + len -= 10;
> + if (len < 24)
> + goto out;
> str +=
> sprintf(str,
> "Algorithm: %02X %02X %02X %02X\nEncscheme: %02X %02X\n"
> "Sigscheme: %02X %02X\nParameters: %02X %02X %02X %02X"
> - " %02X %02X %02X %02X %02X %02X %02X %02X\n"
> - "Modulus length: %d\nModulus: \n",
> - data[10], data[11], data[12], data[13], data[14],
> - data[15], data[16], data[17], data[22], data[23],
> - data[24], data[25], data[26], data[27], data[28],
> - data[29], data[30], data[31], data[32], data[33],
> - be32_to_cpu(*((__be32 *) (data + 34))));
> -
> - for (i = 0; i < 256; i++) {
> - str += sprintf(str, "%02X ", data[i + 38]);
> + " %02X %02X %02X %02X %02X %02X %02X %02X\n",
> + data[0], data[1], data[2], data[3],
> + data[4], data[5],
> + data[6], data[7],
> + data[12], data[13], data[14], data[15], data[16], data[17],
> + data[18], data[19], data[20], data[21], data[22], data[23]);
> + /* Skip TPM_KEY_PARMS.parms and TPM_STORE_PBUKEY.keyLength */
> + i = 4 + 2 + 2 + 4 + be32_to_cpu(*((__be32 *) (data + 8))) + 4;
> + if (i > len)
> + goto out;
> + data += i;
> + len -= i;
> + key_len = be32_to_cpu(*((__be32 *) (data) - 1));
> +
> + /* Note: The value printed here is the TPM_STORE_PUBKEY. For RSA keys
> + this is a modulus, but it can vary for other key types. */
> + str += sprintf(str, "Modulus length: %d\nModulus: \n", key_len);
> +
> + /* len is bounded, so key_len is bounded, so sprintf is bounded, so
> + str doesn't overflow. Well, maybe. */
> + if (key_len > len)
> + goto out;
> + for (i = 0; i < key_len; i++) {
> + str += sprintf(str, "%02X ", data[i]);
> if ((i + 1) % 16 == 0)
> str += sprintf(str, "\n");
> }