linux-toradex.git/lib/mpi, branch v4.9.62

lib/mpi: kunmap after finishing accessing buffer

2017-09-07T06:35:40+00:00

commit dea3eb8b452e36cf2dd572b0a797915ccf452ae6 upstream.

Using sg_miter_start and sg_miter_next, the buffer of an SG is kmap'ed
to *buff. The current code calls sg_miter_stop (and thus kunmap) on the
SG entry before the last access of *buff.

The patch moves the sg_miter_stop call after the last access to *buff to
ensure that the memory pointed to by *buff is still mapped.

Fixes: 4816c9406430 ("lib/mpi: Fix SG miter leak")
Signed-off-by: Stephan Mueller 
Signed-off-by: Herbert Xu 
Signed-off-by: Greg Kroah-Hartman

mpi: Fix NULL ptr dereference in mpi_powm() [ver #3]

2016-11-25T01:57:50+00:00

This fixes CVE-2016-8650.

If mpi_powm() is given a zero exponent, it wants to immediately return
either 1 or 0, depending on the modulus.  However, if the result was
initalised with zero limb space, no limbs space is allocated and a
NULL-pointer exception ensues.

Fix this by allocating a minimal amount of limb space for the result when
the 0-exponent case when the result is 1 and not touching the limb space
when the result is 0.

This affects the use of RSA keys and X.509 certificates that carry them.

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [] mpi_powm+0x32/0x7e6
PGD 0
Oops: 0002 [#1] SMP
Modules linked in:
CPU: 3 PID: 3014 Comm: keyctl Not tainted 4.9.0-rc6-fscache+ #278
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
task: ffff8804011944c0 task.stack: ffff880401294000
RIP: 0010:[]  [] mpi_powm+0x32/0x7e6
RSP: 0018:ffff880401297ad8  EFLAGS: 00010212
RAX: 0000000000000000 RBX: ffff88040868bec0 RCX: ffff88040868bba0
RDX: ffff88040868b260 RSI: ffff88040868bec0 RDI: ffff88040868bee0
RBP: ffff880401297ba8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000047 R11: ffffffff8183b210 R12: 0000000000000000
R13: ffff8804087c7600 R14: 000000000000001f R15: ffff880401297c50
FS:  00007f7a7918c700(0000) GS:ffff88041fb80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000401250000 CR4: 00000000001406e0
Stack:
 ffff88040868bec0 0000000000000020 ffff880401297b00 ffffffff81376cd4
 0000000000000100 ffff880401297b10 ffffffff81376d12 ffff880401297b30
 ffffffff81376f37 0000000000000100 0000000000000000 ffff880401297ba8
Call Trace:
 [] ? __sg_page_iter_next+0x43/0x66
 [] ? sg_miter_get_next_page+0x1b/0x5d
 [] ? sg_miter_next+0x17/0xbd
 [] ? mpi_read_raw_from_sgl+0xf2/0x146
 [] rsa_verify+0x9d/0xee
 [] ? pkcs1pad_sg_set_buf+0x2e/0xbb
 [] pkcs1pad_verify+0xc0/0xe1
 [] public_key_verify_signature+0x1b0/0x228
 [] x509_check_for_self_signed+0xa1/0xc4
 [] x509_cert_parse+0x167/0x1a1
 [] x509_key_preparse+0x21/0x1a1
 [] asymmetric_key_preparse+0x34/0x61
 [] key_create_or_update+0x145/0x399
 [] SyS_add_key+0x154/0x19e
 [] do_syscall_64+0x80/0x191
 [] entry_SYSCALL64_slow_path+0x25/0x25
Code: 56 41 55 41 54 53 48 81 ec a8 00 00 00 44 8b 71 04 8b 42 04 4c 8b 67 18 45 85 f6 89 45 80 0f 84 b4 06 00 00 85 c0 75 2f 41 ff ce <49> c7 04 24 01 00 00 00 b0 01 75 0b 48 8b 41 18 48 83 38 01 0f
RIP  [] mpi_powm+0x32/0x7e6
 RSP 
CR2: 0000000000000000
---[ end trace d82015255d4a5d8d ]---

Basically, this is a backport of a libgcrypt patch:

	http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=patch;h=6e1adb05d290aeeb1c230c763970695f4a538526

Fixes: cdec9cb5167a ("crypto: GnuPG based MPI lib - source files (part 1)")
Signed-off-by: Andrey Ryabinin 
Signed-off-by: David Howells 
cc: Dmitry Kasatkin 
cc: linux-ima-devel@lists.sourceforge.net
cc: stable@vger.kernel.org
Signed-off-by: James Morris

lib/mpi: Fix SG miter leak

2016-07-29T10:30:16+00:00

In mpi_read_raw_from_sgl we may leak the SG miter resouces after
reading the leading zeroes.  This patch fixes this by stopping the
iteration once the leading zeroes have been read.

Fixes: 127827b9c295 ("lib/mpi: Do not do sg_virt")
Reported-by: Nicolai Stange 
Tested-by: Nicolai Stange 
Signed-off-by: Herbert Xu

lib/mpi: Do not do sg_virt

2016-07-01T15:45:18+00:00

Currently the mpi SG helpers use sg_virt which is completely
broken.  It happens to work with normal kernel memory but will
fail with anything that is not linearly mapped.

This patch fixes this by using the SG iterator helpers.

Signed-off-by: Herbert Xu

crypto: rsa - Generate fixed-length output

2016-07-01T15:45:18+00:00

Every implementation of RSA that we have naturally generates
output with leading zeroes.  The one and only user of RSA,
pkcs1pad wants to have those leading zeroes in place, in fact
because they are currently absent it has to write those zeroes
itself.

So we shouldn't be stripping leading zeroes in the first place.
In fact this patch makes rsa-generic produce output with fixed
length so that pkcs1pad does not need to do any extra work.

This patch also changes DH to use the new interface.

Signed-off-by: Herbert Xu

lib/mpi: refactor mpi_read_from_buffer() in terms of mpi_read_raw_data()

2016-05-31T08:42:01+00:00

mpi_read_from_buffer() and mpi_read_raw_data() do basically the same thing
except that the former extracts the number of payload bits from the first
two bytes of the input buffer.

Besides that, the data copying logic is exactly the same.

Replace the open coded buffer to MPI instance conversion by a call to
mpi_read_raw_data().

Signed-off-by: Nicolai Stange 
Signed-off-by: Herbert Xu

lib/mpi: mpi_read_from_buffer(): sanitize short buffer printk

2016-05-31T08:42:00+00:00

The first two bytes of the input buffer encode its expected length and
mpi_read_from_buffer() prints a console message if the given buffer is too
short.

However, there are some oddities with how this message is printed:
- It is printed at the default loglevel. This is different from the
  one used in the case that the first two bytes' value is unsupportedly
  large, i.e. KERN_INFO.
- The format specifier '%d' is used for unsigned ints.
- It prints the values of nread and *ret_nread. This is redundant since
  the former is always the latter + 1.

Clean this up as follows:
- Use pr_info() rather than printk() with no loglevel.
- Use the format specifiers '%u' in place if '%d'.
- Do not print the redundant 'nread' but the more helpful 'nbytes' value.

Signed-off-by: Nicolai Stange 
Signed-off-by: Herbert Xu

lib/mpi: mpi_read_from_buffer(): return -EINVAL upon too short buffer

2016-05-31T08:42:00+00:00

Currently, if the input buffer is shorter than the expected length as
indicated by its first two bytes, an MPI instance of this expected length
will be allocated and filled with as much data as is available. The rest
will remain uninitialized.

Instead of leaving this condition undetected, an error code should be
reported to the caller.

Since this situation indicates that the input buffer's first two bytes,
encoding the number of expected bits, are garbled, -EINVAL is appropriate
here.

If the input buffer is shorter than indicated by its first two bytes,
make mpi_read_from_buffer() return -EINVAL.
Get rid of the 'nread' variable: with the new semantics, the total number
of bytes read from the input buffer is known in advance.

Signed-off-by: Nicolai Stange 
Signed-off-by: Herbert Xu

lib/mpi: mpi_read_from_buffer(): return error code

2016-05-31T08:41:59+00:00

mpi_read_from_buffer() reads a MPI from a buffer into a newly allocated
MPI instance. It expects the buffer's leading two bytes to contain the
number of bits, followed by the actual payload.

On failure, it returns NULL and updates the in/out argument ret_nread
somewhat inconsistently:
- If the given buffer is too short to contain the leading two bytes
  encoding the number of bits or their value is unsupported, then
  ret_nread will be cleared.
- If the allocation of the resulting MPI instance fails, ret_nread is left
  as is.

The only user of mpi_read_from_buffer(), digsig_verify_rsa(), simply checks
for a return value of NULL and returns -ENOMEM if that happens.

While this is all of cosmetic nature only, there is another error condition
which currently isn't detectable by the caller of mpi_read_from_buffer():
if the given buffer is too small to hold the number of bits as encoded in
its first two bytes, the return value will be non-NULL and *ret_nread > 0.

In preparation of communicating this condition to the caller, let
mpi_read_from_buffer() return error values by means of the ERR_PTR()
mechanism.

Make the sole caller of mpi_read_from_buffer(), digsig_verify_rsa(),
check the return value for IS_ERR() rather than == NULL. If IS_ERR() is
true, return the associated error value rather than the fixed -ENOMEM.

Signed-off-by: Nicolai Stange 
Signed-off-by: Herbert Xu

lib/mpi: mpi_read_raw_data(): fix nbits calculation

2016-05-31T08:41:59+00:00

The number of bits, nbits, is calculated in mpi_read_raw_data() as follows:

  nbits = nbytes * 8;

Afterwards, the number of leading zero bits of the first byte get
subtracted:

  nbits -= count_leading_zeros(buffer[0]);

However, count_leading_zeros() takes an unsigned long and thus,
the u8 gets promoted to an unsigned long.

Thus, the above doesn't subtract the number of leading zeros in the most
significant nonzero input byte from nbits, but the number of leading
zeros of the most significant nonzero input byte promoted to unsigned long,
i.e. BITS_PER_LONG - 8 too many.

Fix this by subtracting

  count_leading_zeros(...) - (BITS_PER_LONG - 8)

from nbits only.

Fixes: e1045992949 ("MPILIB: Provide a function to read raw data into an
                     MPI")
Signed-off-by: Nicolai Stange 
Signed-off-by: Herbert Xu