Add to the Denial of Service section of the man page an explanation about the
three different mitigation Tor has.
Fixes#25248.
Signed-off-by: David Goulet <dgoulet@torproject.org>
When size_t is 32 bits, the unit tests can't fit anything more than
4GB-1 into a size_t.
Additionally, tt_int_op() uses "long" -- we need tt_u64_op() to
safely test uint64_t values for equality.
Bug caused by tests for #24782 fix; not in any released Tor.
This patch changes the algorithm of compute_real_max_mem_in_queues() to
use 0.4 * RAM iff the system has more than or equal to 8 GB of RAM, but
will continue to use the old value of 0.75 * RAM if the system have less
than * GB of RAM available.
This patch also adds tests for compute_real_max_mem_in_queues().
See: https://bugs.torproject.org/24782
This patch makes get_total_system_memory mockable, which allows us to
alter the return value of the function in tests.
See: https://bugs.torproject.org/24782
This patch lifts the list of default directory authorities from config.c
into their own auth_dirs.inc file, which is then included in config.c
using the C preprocessor.
Patch by beastr0.
See: https://bugs.torproject.org/24854
Some anchor don't appear in the final man page so document those so we
understand why we do that in the future.
Part of #25582
Signed-off-by: David Goulet <dgoulet@torproject.org>
Previously, the limit for MAX_PROTOCOLS_TO_EXPAND was actually being applied
in Rust to the maximum number of version (total, for all subprotocols).
Whereas in C, it was being applied to the number of subprotocols that were
allowed. This changes the Rust to match C's behaviour.
The behaviours still do not match, unsurprisingly, but now we know where a
primary difference is: the Rust is validating version ranges more than the C,
so in the C it's possible to call protover_all_supported on a ridiculous
version range like "Sleen=0-4294967294" because the C uses
MAX_PROTOCOLS_TO_EXPAND to count the number of *subprotocols* whereas the Rust
uses it to count the total number of *versions* of all subprotocols.
There's now no difference in these tests w.r.t. the C or Rust: both
fail miserably (well, Rust fails with nice descriptive errors, and C
gives you a traceback, because, well, C).
The DoS potential is slightly higher in C now due to some differences to the
Rust code, see the C_RUST_DIFFERS tags in src/rust/protover/tests/protover.rs.
Also, the comment about "failing at the splitting stage" in Rust wasn't true,
since when we split, we ignore empty chunks (e.g. "1--1" parses into
"(1,None),(None,1)" and "None" can't be parsed into an integer).
Finally, the comment about "Rust seems to experience an internal error" is only
true in debug mode, where u32s are bounds-checked at runtime. In release mode,
code expressing the equivalent of this test will error with
`Err(ProtoverError::Unparseable)` because 4294967295 is too large.
Previously, if "Link=1-5" was supported, and you asked protover_all_supported()
(or protover::all_supported() in Rust) if it supported "Link=3-999", the C
version would return "Link=3-999" and the Rust would return "Link=6-999". These
both behave the same now, i.e. both return "Link=6-999".
During code review and discussion with Chelsea Komlo, she pointed out
that protover::compute_for_old_tor() was a public function whose
return type was `&'static CStr`. We both agree that C-like parts of
APIs should:
1. not be exposed publicly (to other Rust crates),
2. only be called in the appropriate FFI code,
3. not expose types which are meant for FFI code (e.g. `*mut char`,
`CString`, `*const c_int`, etc.) to the pure-Rust code of other
crates.
4. FFI code (e.g. things in `ffi.rs` modules) should _never_ be called
from pure-Rust, not even from other modules in its own crate
(i.e. do not call `protover::ffi::*` from anywhere in
`protover::protoset::*`, etc).
With that in mind, this commit makes the following changes:
* CHANGE `protover::compute_for_old_tor()` to be
visible only at the `pub(crate)` level.
* RENAME `protover::compute_for_old_tor()` to
`protover::compute_for_old_tor_cstr()` to reflect the last change.
* ADD a new `protover::compute_for_old_tor()` function wrapper which
is public and intended for other Rust code to use, which returns a
`&str`.
It was changed to take borrows instead of taking ownership.
* REFACTOR `protover::ffi::protover_is_supported_here()` to use changed method
signature on `protover::is_supported_here()`.
This includes a subtle difference in behaviour to the previous Rust
implementation, where, for each vote that we're computing over, if a single one
fails to parse, we skip it. This now matches the current behaviour in the C
implementation.
* REFACTOR `protover::ffi::protover_compute_vote()` to use
new types and methods.
This includes a subtle difference in behaviour, as in 4258f1e18, where we return
(matching the C impl's return behaviour) earlier than before if parsing failed,
saving us computation in parsing the versions into a
protover::protoset::ProtoSet.
* REFACTOR `protover::ffi::protover_list_supports_protocol_or_later()` to use
new types and methods.
This includes a subtle difference in behaviour, as in 4258f1e18, where we return
(matching the C impl's return behaviour) earlier than before if parsing failed,
saving us computation in parsing the versions into a
protover::protoset::ProtoSet.
* REFACTOR `protover::ffi::protover_list_supports_protocol()` to use new types
and methods.
This includes differences in behaviour to before, which should now more closely
match the C version:
- If parsing a protover `char*` from C, and the string is not parseable, this
function will return 1 early, which matches the C behaviour when protocols
are unparseable. Previously, we would parse it and its version numbers
simultaneously, i.e. there was no fail early option, causing us to spend more
time unnecessarily parsing versions.
* REFACTOR `protover::ffi::protover_all_supported()` to use new types and
methods.
Previously, the rust implementation of protover considered an empty string to be
a valid ProtoEntry, while the C version did not (it must have a "=" character).
Other differences include that unknown protocols must now be parsed as
`protover::UnknownProtocol`s, and hence their entries as
`protover::UnvalidatedProtoEntry`s, whereas before (nearly) all protoentries
could be parsed regardless of how erroneous they might be considered by the C
version.
My apologies for this somewhat messy and difficult to read commit, if any part
is frustrating to the reviewer, please feel free to ask me to split this into
smaller changes (possibly hard to do, since so much changed), or ask me to
comment on a specific line/change and clarify how/when the behaviours differ.
The tests here should more closely match the behaviours exhibited by the C
implementation, but I do not yet personally guarantee they match precisely.
* REFACTOR unittests in protover::protover.
* ADD new integration tests for previously untested behaviour.
* FIXES part of #24031: https://bugs.torproject.org/24031.
This changes `protover::is_supported_here()` to be aware of new datatypes
(e.g. don't call `.0` on things which are no longer tuple structs) and also
changes the method signature to take borrows, making it faster, threadable, and
easier to read (i.e. the caller can know from reading the function signature
that the function won't mutate values passed into it).
* CHANGE the `protover::is_supported_here()` function to take borrows.
* REFACTOR the `protover::is_supported_here()` function to be aware of new
datatypes.
* FIXES part of #24031: https://bugs.torproject.org/24031
This adds a new type for votes upon `protover::ProtoEntry`s (technically, on
`protover::UnvalidatedProtoEntry`s, because the C code does not validate based
upon currently known protocols when voting, in order to maintain
future-compatibility), and converts several functions which would have operated
on this datatype into methods for ease-of-use and readability.
This also fixes a behavioural differentce to the C version of
protover_compute_vote(). The C version of protover_compute_vote() calls
expand_protocol_list() which checks if there would be too many subprotocols *or*
expanded individual version numbers, i.e. more than MAX_PROTOCOLS_TO_EXPAND, and
does this *per vote* (but only in compute_vote(), everywhere else in the C seems
to only care about the number of subprotocols, not the number of individual
versions). We need to match its behaviour in Rust and ensure we're not allowing
more than it would to get the votes to match.
* ADD new `protover::ProtoverVote` datatype.
* REMOVE the `protover::compute_vote()` function and refactor it into an
equivalent-in-behaviour albeit more memory-efficient voting algorithm based
on the new underlying `protover::protoset::ProtoSet` datatype, as
`ProtoverVote::compute()`.
* REMOVE the `protover::write_vote_to_string()` function, since this
functionality is now generated by the impl_to_string_for_proto_entry!() macro
for both `ProtoEntry` and `UnvalidatedProtoEntry` (the latter of which is the
correct type to return from a voting protocol instance, since the entity
voting may not know of all protocols being voted upon or known about by other
voting parties).
* FIXES part of #24031: https://bugs.torproject.org/24031
rust: Fix a difference in compute_vote() behaviour to C version.
This implements conversions from either a ProtoEntry or an UnvalidatedProtoEntry
into a String, for use in replacing such functions as
`protover::write_vote_to_string()`.
* ADD macro for implementing ToString trait for ProtoEntry and
UnvalidatedProtoEntry.
* FIXES part of #24031: https://bugs.torproject.org/24031
