To prevent dropping the same message over and over again, the UDP proxy
test application programs/test/udp_proxy _logically_ maintains a mapping
from records to the number of times the record has already been dropped,
and stops dropping once a configurable threshold (currently 2) is passed.
However, the actual implementation deviates from this logical view
in two crucial respects:
- To keep the implementation simple and independent of
implementations of suitable map interfaces, it only counts how
many times a record of a given _size_ has been dropped, and
stops dropping further records of that size once the configurable
threshold is passed. Of course, this is not fail-proof, but a
good enough approximation for the proxy, and it allows to use
an inefficient but simple array for the required map.
- The implementation mixes datagram lengths and record lengths:
When deciding whether it is allowed to drop a datagram, it
uses the total datagram size as a lookup index into the map
counting the number of times a package has been dropped. However,
when updating this map, the UDP proxy traverses the datagram
record by record, and updates the mapping at the level of record
lengths.
Apart from this inconsistency, the current implementation suffers
from a lack of bounds checking for the parsed length of incoming
DTLS records that can lead to a buffer overflow when facing
malformed records.
This commit removes the inconsistency in datagram vs. record length
and resolves the buffer overflow issue by not attempting any dissection
of datagrams into records, and instead only counting how often _datagrams_
of a particular size have been dropped.
There is only one practical situation where this makes a difference:
If datagram packing is used by default but disabled on retransmission
(which OpenSSL has been seen to do), it can happen that we drop a
datagram in its initial transmission, then also drop some of its records
when they retransmitted one-by-one afterwards, yet still keeping the
drop-counter at 1 instead of 2. However, even in this situation, we'll
correctly count the number of droppings from that point on and eventually
stop dropping, because the peer will not fall back to using packing
and hence use stable record lengths.
The library/net.c and its corresponding include/mbedtls/net.h file are
renamed to library/net_sockets.c and include/mbedtls/net_sockets.h
respectively. This is to avoid naming collisions in projects which also
have files with the common name 'net'.
* development: (100 commits)
Update Changelog for the mem-measure branch
Fix issues introduced when rebasing
Fix compile error in memory_buffer_alloc_selftest
Code cosmetics
Add curve25519 to ecc-heap.sh
Add curve25519 to the benchmark program
Fix compile issue when buffer_alloc not available
New script ecc-heap.sh
Fix unused variable issue in some configs
Rm usunused member in private struct
Add heap usage for PK in benchmark
Use memory_buffer_alloc() in benchmark if available
Only define mode_func if mode is enabled (CBC etc)
PKCS8 encrypted key depend on PKCS5 or PKCS12
Disable SRV_C for client measurement
Output stack+heap usage with massif
Enable NIST_OPTIM by default for config-suite-b
Refactor memory.sh
Adapt memory.sh to config-suite-b
Adapt mini-client for config-suite-b.h
...
Conflicts:
ChangeLog
include/polarssl/net.h
library/Makefile
library/error.c
library/ssl_tls.c
programs/Makefile
programs/ssl/ssl_client2.c
programs/ssl/ssl_server2.c
tests/Makefile
There seemed to be some race conditions with server closing its fd right after
sending HelloVerifyRequest causing the proxy to exit after a failed read.
