[tcpip] Avoid generating positive zero for transmitted UDP checksums
TCP/IP checksum fields are one's complement values and therefore have
two possible representations of zero: positive zero (0x0000) and
negative zero (0xffff).
In RFC768, UDP over IPv4 exploits this redundancy to repurpose the
positive representation of zero (0x0000) to mean "no checksum
calculated"; checksums are optional for UDP over IPv4.
In RFC2460, checksums are made mandatory for UDP over IPv4. The
wording of the RFC is such that the UDP header is mandated to use only
the negative representation of zero (0xffff), rather than simply
requiring the checksum to be correct but allowing for either
representation of zero to be used.
In RFC1071, an example algorithm is given for calculating the TCP/IP
checksum. This algorithm happens to produce only the positive
representation of zero (0x0000); this is an artifact of the way that
unsigned arithmetic is used to calculate a signed one's complement
sum (and its final negation).
A common misconception has developed (exemplified in RFC1624) that
this artifact is part of the specification. Many people have assumed
that the checksum field should never contain the negative
representation of zero (0xffff).
A sensible receiver will calculate the checksum over the whole packet
and verify that the result is zero (in whichever representation of
zero happens to be generated by the receiver's algorithm). Such a
receiver will not care which representation of zero happens to be used
in the checksum field.
However, there are receivers in existence which will verify the
received checksum the hard way: by calculating the checksum over the
remainder of the packet and comparing the result against the checksum
field. If the representation of zero used by the receiver's algorithm
does not match the representation of zero used by the transmitter (and
so placed in the checksum field), and if the receiver does not
explicitly allow for both representations to compare as equal, then
the receiver may reject packets with a valid checksum.
For UDP, the combined RFCs effectively mandate that we should generate
only the negative representation of zero in the checksum field.
For IP, TCP and ICMP, the RFCs do not mandate which representation of
zero should be used, but the misconceptions which have grown up around
RFC1071 and RFC1624 suggest that it would be least surprising to
generate only the positive representation of zero in the checksum
field.
Fix by ensuring that all of our checksum algorithms generate only the
positive representation of zero, and explicitly inverting this in the
case of transmitted UDP packets.
Reported-by: Wissam Shoukair <wissams@mellanox.com>
Tested-by: Wissam Shoukair <wissams@mellanox.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Merge the functionality of parse_next_server_and_filename() and
tftp_uri() into a single pxe_uri(), which takes a server address
(IPv4/IPv6/none) and a filename, and produces a URI using the rule:
- if the filename is a hierarchical absolute URI (i.e. includes a
scheme such as "http://" or "tftp://") then use that URI and ignore
the server address,
- otherwise, if the server address is recognised (according to
sa_family) then construct a TFTP URI based on the server address,
port, and filename
- otherwise fail.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Commit 09b057c ("[settings] Remove "uristring" setting type") removed
support for URI-encoded settings via the "uristring" setting type, on
the basis that such encoding was no longer necessary to avoid problems
with the command line parser.
Other valid use cases for the "uristring" setting type do exist: for
example, a password containing a '/' character expanded via
chain http://username:${password:uristring}@server.name/boot.php
Restore the existence of the "uristring" setting, avoiding the
potentially large stack allocations that were used in the old code
prior to commit 09b057c ("[settings] Remove "uristring" setting
type").
Requested-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[image] Detect image type when image is first registered
The current usage pattern of image_probe() is a legacy from the time
before commit 34b6ecb ("[image] Simplify image management") when
loading an image to its executable location in memory was a separate
action from actually executing the image.
Call image_probe() as soon as an image is registered. This allows
"imgstat" to display image type information for all images and allows
image-consuming code to assume that image->type is already set
correctly.
Ignore failures if image_probe() does not recognise the image, since
we do expect to handle unrecognised images (initrds, modules, etc).
Unrecognised images will be left with a NULL image->type, which
image-consuming code can easily check.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow line buffer to accumulate multiple lines, with buffered_line()
returning each freshly-completed line as it is encountered. This
allows buffered lines to be subsequently processed as a group.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[ipv4] Redefine IP address constants to avoid unnecessary byte swapping
Redefine various IPv4 address constants and testing macros to avoid
unnecessary byte swapping at runtime, and slightly rename the macros
to prevent code from accidentally using the old definitions.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Generalise the existing support for performing CBC-mode block cipher
tests, and update the code to use okx() for neater reporting of test
results.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[base16] Add buffer size parameter to base16_encode() and base16_decode()
The current API for Base16 (and Base64) encoding requires the caller
to always provide sufficient buffer space. This prevents the use of
the generic encoding/decoding functionality in some situations, such
as in formatting the hex setting types.
Implement a generic hex_encode() (based on the existing
format_hex_setting()), implement base16_encode() and base16_decode()
in terms of the more generic hex_encode() and hex_decode(), and update
all callers to provide the additional buffer length parameter.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[test] Include IPv6 support when performing settings self-tests
The settings self-tests include tests for the "ipv6" setting type.
When IPv6 support is not included, this setting type exists (since it
is referred to by some dual-stack code, such as dns.c) but is
non-functional.
Force IPv6 support to be included within a settings self-test build
using an explicit REQUIRE_OBJECT() macro.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
SHA-512/224 is almost identical to SHA-512, with differing initial
hash values and a truncated output length.
This implementation has been verified using the NIST SHA-512/224 test
vectors.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
SHA-512/256 is almost identical to SHA-512, with differing initial
hash values and a truncated output length.
This implementation has been verified using the NIST SHA-512/256 test
vectors.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
SHA-384 is almost identical to SHA-512, with differing initial hash
values and a truncated output length.
This implementation has been verified using the NIST SHA-384 test
vectors.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
SHA-224 is almost identical to SHA-256, with differing initial hash
values and a truncated output length.
This implementation has been verified using the NIST SHA-224 test
vectors.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Update the digest self-tests to use okx(), and centralise concepts and
data shared between tests for multiple algorithms to reduce duplicated
code.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
At some point in the past few years, binutils became more aggressive
at removing unused symbols. To function as a symbol requirement, a
relocation record must now be in a section marked with @progbits and
must not be in a section which gets discarded during the link (either
via --gc-sections or via /DISCARD/).
Update REQUIRE_SYMBOL() to generate relocation records meeting these
criteria. To minimise the impact upon the final binary size, we use
existing symbols (specified via the REQUIRING_SYMBOL() macro) as the
relocation targets where possible. We use R_386_NONE or R_X86_64_NONE
relocation types to prevent any actual unwanted relocation taking
place. Where no suitable symbol exists for REQUIRING_SYMBOL() (such
as in config.c), the macro PROVIDE_REQUIRING_SYMBOL() can be used to
generate a one-byte-long symbol to act as the relocation target.
If there are versions of binutils for which this approach fails, then
the fallback will probably involve killing off REQUEST_SYMBOL(),
redefining REQUIRE_SYMBOL() to use the current definition of
REQUEST_SYMBOL(), and postprocessing the linked ELF file with
something along the lines of "nm -u | wc -l" to check that there are
no undefined symbols remaining.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The implementation of strtoul() has a partially unknown provenance.
Rewrite this code to avoid potential licensing uncertainty.
Since we now use -ffunction-sections, there is no need to place
strtoull() in a separate file from strtoul().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The implementation of inet_aton() has an unknown provenance. Rewrite
this code to avoid potential licensing uncertainty.
Also move the code from core/misc.c to its logical home in net/ipv4.c,
and add a few extra test cases.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[crypto] Fix parsing of OCSP responder ID key hash
We currently compare the entirety of the KeyHash object (including the
ASN.1 tag and length byte) against the raw SHA-1 hash of the
certificate's public key. This causes OCSP validation to fail for any
responses which identify the responder by key hash rather than by
name, and hence prevents the use of X.509 certificates where any
certificate in the chain has an OCSP responder which chooses to
identify itself via its key hash.
Fix by adding the missing asn1_enter() required to enter the ASN.1
octet string containing the key hash.
Also add a corresponding test case including an OCSP response where
the responder is identified by key hash, to ensure that this
functionality cannot be broken in future.
Debugged-by: Brian Rak <brak@gameservers.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Fix an erroneous htonl() in the definition of IN6_IS_ADDR_LINKLOCAL(),
and add self-tests for the IN6_IS_ADDR_xxx() family of macros.
Reported-by: Marin Hannache <git@mareo.fr>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[libc] Prevent strndup() from reading beyond the end of the string
strndup() may be called on a string which is not NUL-terminated. Use
strnlen() instead of strlen() to ensure that we do not read beyond the
end of such a string.
Add self-tests for strndup(), including a test case with an
unterminated string.
Originally-fixed-by: Marin Hannache <git@mareo.fr>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[test] Check for correct -mrtd assumption on libgcc arithmetic functions
As observed in commit 082cedb ("[build] Fix __libgcc attribute for
recent gcc versions"), recent versions of gcc have changed the
semantics of -mrtd as applied to the implicit arithmetic functions.
It is possible for tests to succeed even if our assumptions about
gcc's interpretation of -mrtd are incorrect. In particular, if gcc
chooses to utilise a frame pointer in the calling function, then it
can tolerate a temporarily incorrect stack pointer (since the stack
pointer will shortly afterwards be restored from the frame pointer
anyway).
Add tests designed specifically to check that our implementations of
the implicit arithmetic functions manipulate the stack pointer as
expected by gcc.
The effect of these tests can be observed by temporarily reverting
commit 082cedb ("[build] Fix __libgcc attribute for recent gcc
versions"): without this fix in place, the tests will fail on gcc 4.7
and later.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
On a 32-bit system, 64-bit division is implemented using the libgcc
functions provided in __udivmoddi4.c etc. Calls to these functions
are generated automatically by gcc, with a calling convention that is
somewhat empirical in nature. Add these self-tests primarily as a
check that we are using the correct calling convention.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown