Within the copying loop in mpi_read_raw_from_sgl(), the last input SGE's
byte count gets artificially extended as follows:
if (sg_is_last(sg) && (len % BYTES_PER_MPI_LIMB))
len += BYTES_PER_MPI_LIMB - (len % BYTES_PER_MPI_LIMB);
Within the following byte copying loop, this causes reads beyond that
SGE's allocated buffer:
BUG: KASAN: slab-out-of-bounds in mpi_read_raw_from_sgl+0x331/0x650
at addr ffff8801e168d4d8
Read of size 1 by task systemd-udevd/721
[...]
Call Trace:
[<ffffffff818c4d35>] dump_stack+0xbc/0x117
[<ffffffff818c4c79>] ? _atomic_dec_and_lock+0x169/0x169
[<ffffffff814af5d1>] ? print_section+0x61/0xb0
[<ffffffff814b1109>] print_trailer+0x179/0x2c0
[<ffffffff814bc524>] object_err+0x34/0x40
[<ffffffff814bfdc7>] kasan_report_error+0x307/0x8c0
[<ffffffff814bf315>] ? kasan_unpoison_shadow+0x35/0x50
[<ffffffff814bf38e>] ? kasan_kmalloc+0x5e/0x70
[<ffffffff814c0ad1>] kasan_report+0x71/0xa0
[<ffffffff81938171>] ? mpi_read_raw_from_sgl+0x331/0x650
[<ffffffff814bf1a6>] __asan_load1+0x46/0x50
[<ffffffff81938171>] mpi_read_raw_from_sgl+0x331/0x650
[<ffffffff817f41b6>] rsa_verify+0x106/0x260
[<ffffffff817f40b0>] ? rsa_set_pub_key+0xf0/0xf0
[<ffffffff818edc79>] ? sg_init_table+0x29/0x50
[<ffffffff817f4d22>] ? pkcs1pad_sg_set_buf+0xb2/0x2e0
[<ffffffff817f5b74>] pkcs1pad_verify+0x1f4/0x2b0
[<ffffffff81831057>] public_key_verify_signature+0x3a7/0x5e0
[<ffffffff81830cb0>] ? public_key_describe+0x80/0x80
[<ffffffff817830f0>] ? keyring_search_aux+0x150/0x150
[<ffffffff818334a4>] ? x509_request_asymmetric_key+0x114/0x370
[<ffffffff814b83f0>] ? kfree+0x220/0x370
[<ffffffff818312c2>] public_key_verify_signature_2+0x32/0x50
[<ffffffff81830b5c>] verify_signature+0x7c/0xb0
[<ffffffff81835d0c>] pkcs7_validate_trust+0x42c/0x5f0
[<ffffffff813c391a>] system_verify_data+0xca/0x170
[<ffffffff813c3850>] ? top_trace_array+0x9b/0x9b
[<ffffffff81510b29>] ? __vfs_read+0x279/0x3d0
[<ffffffff8129372f>] mod_verify_sig+0x1ff/0x290
[...]
The exact purpose of the len extension isn't clear to me, but due to
its form, I suspect that it's a leftover somehow accounting for leading
zero bytes within the most significant output limb.
Note however that without that len adjustement, the total number of bytes
ever processed by the inner loop equals nbytes and thus, the last output
limb gets written at this point. Thus the net effect of the len adjustement
cited above is just to keep the inner loop running for some more
iterations, namely < BYTES_PER_MPI_LIMB ones, reading some extra bytes from
beyond the last SGE's buffer and discarding them afterwards.
Fix this issue by purging the extension of len beyond the last input SGE's
buffer length.
Fixes: 2d4d1eea54 ("lib/mpi: Add mpi sgl helpers")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Within the byte reading loop in mpi_read_raw_sgl(), there are two
housekeeping indices used, z and x.
At all times, the index z represents the number of output bytes covered
by the input SGEs for which processing has completed so far. This includes
any leading zero bytes within the most significant limb.
The index x changes its meaning after the first outer loop's iteration
though: while processing the first input SGE, it represents
"number of leading zero bytes in most significant output limb" +
"current position within current SGE"
For the remaining SGEs OTOH, x corresponds just to
"current position within current SGE"
After all, it is only the sum of z and x that has any meaning for the
output buffer and thus, the
"number of leading zero bytes in most significant output limb"
part can be moved away from x into z from the beginning, opening up the
opportunity for cleaner code.
Before the outer loop iterating over the SGEs, don't initialize z with
zero, but with the number of leading zero bytes in the most significant
output limb. For the inner loop iterating over a single SGE's bytes,
get rid of the buf_shift offset to x' bounds and let x run from zero to
sg->length - 1.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The number of bits, nbits, is calculated in mpi_read_raw_from_sgl() as
follows:
nbits = nbytes * 8;
Afterwards, the number of leading zero bits of the first byte get
subtracted:
nbits -= count_leading_zeros(*(u8 *)(sg_virt(sgl) + lzeros));
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: 2d4d1eea54 ("lib/mpi: Add mpi sgl helpers")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
In mpi_read_raw_from_sgl(), unsigned nbits is calculated as follows:
nbits = nbytes * 8;
and redundantly cleared later on if nbytes == 0:
if (nbytes > 0)
...
else
nbits = 0;
Purge this redundant clearing for the sake of clarity.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
At the very beginning of mpi_read_raw_from_sgl(), the leading zeros of
the input scatterlist are counted:
lzeros = 0;
for_each_sg(sgl, sg, ents, i) {
...
if (/* sg contains nonzero bytes */)
break;
/* sg contains nothing but zeros here */
ents--;
lzeros = 0;
}
Later on, the total number of trailing nonzero bytes is calculated by
subtracting the number of leading zero bytes from the total number of input
bytes:
nbytes -= lzeros;
However, since lzeros gets reset to zero for each completely zero leading
sg in the loop above, it doesn't include those.
Besides wasting resources by allocating a too large output buffer,
this mistake propagates into the calculation of x, the number of
leading zeros within the most significant output limb:
x = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
What's more, the low order bytes of the output, equal in number to the
extra bytes in nbytes, are left uninitialized.
Fix this by adjusting nbytes for each completely zero leading scatterlist
entry.
Fixes: 2d4d1eea54 ("lib/mpi: Add mpi sgl helpers")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently, the nbytes local variable is calculated from the len argument
as follows:
... mpi_read_raw_from_sgl(..., unsigned int len)
{
unsigned nbytes;
...
if (!ents)
nbytes = 0;
else
nbytes = len - lzeros;
...
}
Given that nbytes is derived from len in a trivial way and that the len
argument is shadowed by a local len variable in several loops, this is just
confusing.
Rename the len argument to nbytes and get rid of the nbytes local variable.
Do the nbytes calculation in place.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently, mpi_read_buffer() writes full limbs to the output buffer
and moves memory around to purge leading zero limbs afterwards.
However, with
commit 9cbe21d8f8 ("lib/mpi: only require buffers as big as needed for
the integer")
the caller is only required to provide a buffer large enough to hold the
result without the leading zeros.
This might result in a buffer overflow for small MP numbers with leading
zeros.
Fix this by coping the result to its final destination within the output
buffer and not copying the leading zeros at all.
Fixes: 9cbe21d8f8 ("lib/mpi: only require buffers as big as needed for
the integer")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently, the endian conversion from CPU order to BE is open coded in
mpi_read_buffer().
Replace this by the centrally provided cpu_to_be*() macros.
Copy from the temporary storage on stack to the destination buffer
by means of memcpy().
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently, if the number of leading zeros is greater than fits into a
complete limb, mpi_read_buffer() skips them by iterating over them
limb-wise.
Instead of skipping the high order zero limbs within the loop as shown
above, adjust the copying loop's bounds.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently, the endian conversion from CPU order to BE is open coded in
mpi_write_sgl().
Replace this by the centrally provided cpu_to_be*() macros.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Within the copying loop in mpi_write_sgl(), we have
if (lzeros) {
mpi_limb_t *limb1 = (void *)p - sizeof(alimb);
mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
+ lzeros;
*limb1 = *limb2;
...
}
where p points past the end of alimb2 which lives on the stack and contains
the current limb in BE order.
The purpose of the above is to shift the non-zero bytes of alimb2 to its
beginning in memory, i.e. to skip its leading zero bytes.
However, limb2 points somewhere into the middle of alimb2 and thus, reading
*limb2 pulls in lzero bytes from somewhere.
Indeed, KASAN splats:
BUG: KASAN: stack-out-of-bounds in mpi_write_to_sgl+0x4e3/0x6f0
at addr ffff8800cb04f601
Read of size 8 by task systemd-udevd/391
page:ffffea00032c13c0 count:0 mapcount:0 mapping: (null) index:0x0
flags: 0x3fff8000000000()
page dumped because: kasan: bad access detected
CPU: 3 PID: 391 Comm: systemd-udevd Tainted: G B L
4.5.0-next-20160316+ #12
[...]
Call Trace:
[<ffffffff8194889e>] dump_stack+0xdc/0x15e
[<ffffffff819487c2>] ? _atomic_dec_and_lock+0xa2/0xa2
[<ffffffff814892b5>] ? __dump_page+0x185/0x330
[<ffffffff8150ffd6>] kasan_report_error+0x5e6/0x8b0
[<ffffffff814724cd>] ? kzfree+0x2d/0x40
[<ffffffff819c5bce>] ? mpi_free_limb_space+0xe/0x20
[<ffffffff819c469e>] ? mpi_powm+0x37e/0x16f0
[<ffffffff815109f1>] kasan_report+0x71/0xa0
[<ffffffff819c0353>] ? mpi_write_to_sgl+0x4e3/0x6f0
[<ffffffff8150ed34>] __asan_load8+0x64/0x70
[<ffffffff819c0353>] mpi_write_to_sgl+0x4e3/0x6f0
[<ffffffff819bfe70>] ? mpi_set_buffer+0x620/0x620
[<ffffffff819c0e6f>] ? mpi_cmp+0xbf/0x180
[<ffffffff8186e282>] rsa_verify+0x202/0x260
What's more, since lzeros can be anything from 1 to sizeof(mpi_limb_t)-1,
the above will cause unaligned accesses which is bad on non-x86 archs.
Fix the issue, by preparing the starting point p for the upcoming copy
operation instead of shifting the source memory, i.e. alimb2.
Fixes: 2d4d1eea54 ("lib/mpi: Add mpi sgl helpers")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Within the copying loop in mpi_write_sgl(), we have
if (lzeros) {
...
p -= lzeros;
y = lzeros;
}
p = p - (sizeof(alimb) - y);
If lzeros == 0, then y == 0, too. Thus, lzeros gets subtracted and added
back again to p.
Purge this redundancy.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Within the copying loop in mpi_write_sgl(), we have
if (lzeros > 0) {
...
lzeros -= sizeof(alimb);
}
However, at this point, lzeros < sizeof(alimb) holds. Make this fact
explicit by rewriting the above to
if (lzeros) {
...
lzeros = 0;
}
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently, if the number of leading zeros is greater than fits into a
complete limb, mpi_write_sgl() skips them by iterating over them limb-wise.
However, it fails to adjust its internal leading zeros tracking variable,
lzeros, accordingly: it does a
p -= sizeof(alimb);
continue;
which should really have been a
lzeros -= sizeof(alimb);
continue;
Since lzeros never decreases if its initial value >= sizeof(alimb), nothing
gets copied by mpi_write_sgl() in that case.
Instead of skipping the high order zero limbs within the loop as shown
above, fix the issue by adjusting the copying loop's bounds.
Fixes: 2d4d1eea54 ("lib/mpi: Add mpi sgl helpers")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The limbs are integers in the host endianness, so we can't simply
iterate over the individual bytes. The current code happens to work on
little-endian, because the order of the limbs in the MPI array is the
same as the order of the bytes in each limb, but it breaks on
big-endian.
Fixes: 0f74fbf77d ("MPI: Fix mpi_read_buffer")
Signed-off-by: Michal Marek <mmarek@suse.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Since mpi_write_to_sgl and mpi_read_buffer explicitly left-align the
integers being written it makes no sense to require a buffer big enough for
the number + the leading zero bytes which are not written. The error
returned also doesn't convey any information. So instead require only the
size needed and return -EOVERFLOW to signal when buffer too short.
Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The asm-generic changes for 4.4 are mostly a series from Christoph Hellwig
to clean up various abuses of headers in there. The patch to rename the
io-64-nonatomic-*.h headers caused some conflicts with new users, so I
added a workaround that we can remove in the next merge window.
The only other patch is a warning fix from Marek Vasut
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1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=dQKG
-----END PGP SIGNATURE-----
Merge tag 'asm-generic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic
Pull asm-generic cleanups from Arnd Bergmann:
"The asm-generic changes for 4.4 are mostly a series from Christoph
Hellwig to clean up various abuses of headers in there. The patch to
rename the io-64-nonatomic-*.h headers caused some conflicts with new
users, so I added a workaround that we can remove in the next merge
window.
The only other patch is a warning fix from Marek Vasut"
* tag 'asm-generic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
asm-generic: temporarily add back asm-generic/io-64-nonatomic*.h
asm-generic: cmpxchg: avoid warnings from macro-ized cmpxchg() implementations
gpio-mxc: stop including <asm-generic/bug>
n_tracesink: stop including <asm-generic/bug>
n_tracerouter: stop including <asm-generic/bug>
mlx5: stop including <asm-generic/kmap_types.h>
hifn_795x: stop including <asm-generic/kmap_types.h>
drbd: stop including <asm-generic/kmap_types.h>
move count_zeroes.h out of asm-generic
move io-64-nonatomic*.h out of asm-generic
The patch fixes the analysis of the input data which contains an off
by one.
The issue is visible when the SGL contains one byte per SG entry.
The code for checking for zero bytes does not operate on the data byte.
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This header contains a few helpers currenly only used by the mpi
implementation, and not default implementation of architecture code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Add mpi_read_raw_from_sgl and mpi_write_to_sgl helpers.
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Change mpi_read_buffer to return a number without leading zeros
so that mpi_read_buffer and mpi_get_buffer return the same thing.
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Added a mpi_read_buf() helper function to export MPI to a buf provided by
the user, and a mpi_get_size() helper, that tells the user how big the buf is.
Changed mpi_free to use kzfree instead of kfree because it is used to free
crypto keys.
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
For 'while' looping, need stop when 'nbytes == 0', or will cause issue.
('nbytes' is size_t which is always bigger or equal than zero).
The related warning: (with EXTRA_CFLAGS=-W)
lib/mpi/mpicoder.c:40:2: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove MIN, MAX and ABS macros that are duplicates kernel's native
implementation.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Provide a function to read raw data of a predetermined size into an MPI rather
than expecting the size to be encoded within the data. The data is assumed to
represent an unsigned integer, and the resulting MPI will be positive.
The function looks like this:
MPI mpi_read_raw_data(const void *, size_t);
This is useful for reading ASN.1 integer primitives where the length is encoded
in the ASN.1 metadata.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
MPI library is used by RSA verification implementation.
Few files contains functions which are never called.
James Morris has asked to remove all of them.
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Requested-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
do_encode_md() and mpi_get_keyid() are not parts of mpi library.
They were used early versions of gnupg and in digsig project,
but they are not used neither here nor there anymore.
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Reviewed-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
MPI_NULL is replaced with normal NULL.
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Reviewed-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
Adds the multi-precision-integer maths library which was originally taken
from GnuPG and ported to the kernel by (among others) David Howells.
This version is taken from Fedora kernel 2.6.32-71.14.1.el6.
The difference is that checkpatch reported errors and warnings have been fixed.
This library is used to implemenet RSA digital signature verification
used in IMA/EVM integrity protection subsystem.
Due to patch size limitation, the patch is divided into 4 parts.
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
