commit dd63b972883f6c0b23ee2f7661b7897b229dd28f Author: Nick Mathewson nickm@torproject.org Date: Wed Oct 14 11:28:37 2020 -0400

Implement proposal 318: Limit protovers to 0..63

In brief: we go through a lot of gymnastics to handle huge protover numbers, but after years of development we're not even close to 10 for any of our current versions. We also have a convenient workaround available in case we ever run out of protocols: if (for example) we someday need Link=64, we can just add Link2=0 or something.

This patch is a minimal patch to change tor's behavior; it doesn't take advantage of the new restrictions.

Implements #40133 and proposal 318. --- changes/ticket40133 | 5 ++ src/core/or/protover.c | 4 +- src/rust/protover/errors.rs | 2 +- src/rust/protover/protoset.rs | 20 +++++--- src/rust/protover/protover.rs | 10 ++-- src/rust/protover/tests/protover.rs | 60 +++++++----------------- src/test/test_protover.c | 91 +++++++++---------------------------- 7 files changed, 66 insertions(+), 126 deletions(-)

diff --git a/changes/ticket40133 b/changes/ticket40133 new file mode 100644 index 0000000000..8bbe00b6b2 --- /dev/null +++ b/changes/ticket40133 @@ -0,0 +1,5 @@ + o Minor features (protocol simplification): + - Tor no longer allows subprotocol versions larger than 63. Previously + versions up to UINT32_MAX were allowed, which significantly complicated + our code. + Implements proposal 318; closes ticket 40133. diff --git a/src/core/or/protover.c b/src/core/or/protover.c index 17979d04ea..dfb0e9e303 100644 --- a/src/core/or/protover.c +++ b/src/core/or/protover.c @@ -113,13 +113,13 @@ proto_entry_free_(proto_entry_t *entry) }

/** The largest possible protocol version. */ -#define MAX_PROTOCOL_VERSION (UINT32_MAX-1) +#define MAX_PROTOCOL_VERSION (63)

/** * Given a string <b>s</b> and optional end-of-string pointer * <b>end_of_range</b>, parse the protocol range and store it in * <b>low_out</b> and <b>high_out</b>. A protocol range has the format U, or - * U-U, where U is an unsigned 32-bit integer. + * U-U, where U is an unsigned integer between 0 and 63 inclusive. */ static int parse_version_range(const char *s, const char *end_of_range, diff --git a/src/rust/protover/errors.rs b/src/rust/protover/errors.rs index dc0d8735f4..04397ac4fe 100644 --- a/src/rust/protover/errors.rs +++ b/src/rust/protover/errors.rs @@ -36,7 +36,7 @@ impl Display for ProtoverError { ProtoverError::Unparseable => write!(f, "The protover string was unparseable."), ProtoverError::ExceedsMax => write!( f, - "The high in a (low, high) protover range exceeds u32::MAX." + "The high in a (low, high) protover range exceeds 63." ), ProtoverError::ExceedsExpansionLimit => write!( f, diff --git a/src/rust/protover/protoset.rs b/src/rust/protover/protoset.rs index 3b283983c8..0ab94457c5 100644 --- a/src/rust/protover/protoset.rs +++ b/src/rust/protover/protoset.rs @@ -294,6 +294,10 @@ impl ProtoSet { } }

+/// Largest allowed protocol version. +/// C_RUST_COUPLED: protover.c `MAX_PROTOCOL_VERSION` +const MAX_PROTOCOL_VERSION: Version = 63; + impl FromStr for ProtoSet { type Err = ProtoverError;

@@ -370,7 +374,7 @@ impl FromStr for ProtoSet { let pieces: ::std::str::Split<char> = version_string.split(',');

for p in pieces { - if p.contains('-') { + let (lo,hi) = if p.contains('-') { let mut pair = p.splitn(2, '-');

let low = pair.next().ok_or(ProtoverError::Unparseable)?; @@ -379,12 +383,17 @@ impl FromStr for ProtoSet { let lo: Version = low.parse().or(Err(ProtoverError::Unparseable))?; let hi: Version = high.parse().or(Err(ProtoverError::Unparseable))?;

- pairs.push((lo, hi)); + (lo,hi) } else { let v: u32 = p.parse().or(Err(ProtoverError::Unparseable))?;

- pairs.push((v, v)); + (v, v) + }; + + if lo > MAX_PROTOCOL_VERSION || hi > MAX_PROTOCOL_VERSION { + return Err(ProtoverError::ExceedsMax); } + pairs.push((lo, hi)); }

ProtoSet::from_slice(&pairs[..]) @@ -674,12 +683,11 @@ mod test {

#[test] fn test_protoset_into_vec() { - let ps: ProtoSet = "1-13,42,9001,4294967294".parse().unwrap(); + let ps: ProtoSet = "1-13,42".parse().unwrap(); let v: Vec<Version> = ps.into();

assert!(v.contains(&7)); - assert!(v.contains(&9001)); - assert!(v.contains(&4294967294)); + assert!(v.contains(&42)); } }

diff --git a/src/rust/protover/protover.rs b/src/rust/protover/protover.rs index 06fdf56c69..536667f61b 100644 --- a/src/rust/protover/protover.rs +++ b/src/rust/protover/protover.rs @@ -866,12 +866,12 @@ mod test {

#[test] fn test_protoentry_from_str_allowed_number_of_versions() { - assert_protoentry_is_parseable!("Desc=1-4294967294"); + assert_protoentry_is_parseable!("Desc=1-63"); }

#[test] fn test_protoentry_from_str_too_many_versions() { - assert_protoentry_is_unparseable!("Desc=1-4294967295"); + assert_protoentry_is_unparseable!("Desc=1-64"); }

#[test] @@ -910,10 +910,10 @@ mod test {

#[test] fn test_protoentry_all_supported_unsupported_high_version() { - let protocols: UnvalidatedProtoEntry = "HSDir=12-100".parse().unwrap(); + let protocols: UnvalidatedProtoEntry = "HSDir=12-60".parse().unwrap(); let unsupported: Option<UnvalidatedProtoEntry> = protocols.all_supported(); assert_eq!(true, unsupported.is_some()); - assert_eq!("HSDir=12-100", &unsupported.unwrap().to_string()); + assert_eq!("HSDir=12-60", &unsupported.unwrap().to_string()); }

#[test] @@ -962,7 +962,7 @@ mod test { ProtoSet::from_str(&versions).unwrap().to_string() );

- versions = "1-3,500"; + versions = "1-3,50"; assert_eq!( String::from(versions), ProtoSet::from_str(&versions).unwrap().to_string() diff --git a/src/rust/protover/tests/protover.rs b/src/rust/protover/tests/protover.rs index 942fe3c6ab..d563202d87 100644 --- a/src/rust/protover/tests/protover.rs +++ b/src/rust/protover/tests/protover.rs @@ -98,10 +98,10 @@ fn protocol_all_supported_with_unsupported_protocol() {

#[test] fn protocol_all_supported_with_unsupported_versions() { - let protocols: UnvalidatedProtoEntry = "Link=3-999".parse().unwrap(); + let protocols: UnvalidatedProtoEntry = "Link=3-63".parse().unwrap(); let unsupported: Option<UnvalidatedProtoEntry> = protocols.all_supported(); assert_eq!(true, unsupported.is_some()); - assert_eq!("Link=6-999", &unsupported.unwrap().to_string()); + assert_eq!("Link=6-63", &unsupported.unwrap().to_string()); }

#[test] @@ -114,10 +114,10 @@ fn protocol_all_supported_with_unsupported_low_version() {

#[test] fn protocol_all_supported_with_unsupported_high_version() { - let protocols: UnvalidatedProtoEntry = "Cons=1-2,999".parse().unwrap(); + let protocols: UnvalidatedProtoEntry = "Cons=1-2,60".parse().unwrap(); let unsupported: Option<UnvalidatedProtoEntry> = protocols.all_supported(); assert_eq!(true, unsupported.is_some()); - assert_eq!("Cons=999", &unsupported.unwrap().to_string()); + assert_eq!("Cons=60", &unsupported.unwrap().to_string()); }

#[test] @@ -195,27 +195,27 @@ fn protover_compute_vote_returns_protocols_that_it_doesnt_currently_support() {

#[test] fn protover_compute_vote_returns_matching_for_mix() { - let protocols: &[UnvalidatedProtoEntry] = &["Link=1-10,500 Cons=1,3-7,8".parse().unwrap()]; + let protocols: &[UnvalidatedProtoEntry] = &["Link=1-10,50 Cons=1,3-7,8".parse().unwrap()]; let listed = ProtoverVote::compute(protocols, &1); - assert_eq!("Cons=1,3-8 Link=1-10,500", listed.to_string()); + assert_eq!("Cons=1,3-8 Link=1-10,50", listed.to_string()); }

#[test] fn protover_compute_vote_returns_matching_for_longer_mix() { let protocols: &[UnvalidatedProtoEntry] = &[ - "Desc=1-10,500 Cons=1,3-7,8".parse().unwrap(), - "Link=123-456,78 Cons=2-6,8 Desc=9".parse().unwrap(), + "Desc=1-10,50 Cons=1,3-7,8".parse().unwrap(), + "Link=12-45,8 Cons=2-6,8 Desc=9".parse().unwrap(), ];

let listed = ProtoverVote::compute(protocols, &1); - assert_eq!("Cons=1-8 Desc=1-10,500 Link=78,123-456", listed.to_string()); + assert_eq!("Cons=1-8 Desc=1-10,50 Link=8,12-45", listed.to_string()); }

#[test] fn protover_compute_vote_returns_matching_for_longer_mix_with_threshold_two() { let protocols: &[UnvalidatedProtoEntry] = &[ - "Desc=1-10,500 Cons=1,3-7,8".parse().unwrap(), - "Link=123-456,78 Cons=2-6,8 Desc=9".parse().unwrap(), + "Desc=1-10,50 Cons=1,3-7,8".parse().unwrap(), + "Link=8,12-45 Cons=2-6,8 Desc=9".parse().unwrap(), ];

let listed = ProtoverVote::compute(protocols, &2); @@ -320,30 +320,20 @@ fn protocol_all_supported_with_single_protocol_and_protocol_range() { assert_eq!(true, unsupported.is_none()); }

-// By allowing us to add to votes, the C implementation allows us to -// exceed the limit. -#[test] -fn protover_compute_vote_may_exceed_limit() { - let proto1: UnvalidatedProtoEntry = "Sleen=1-65535".parse().unwrap(); - let proto2: UnvalidatedProtoEntry = "Sleen=100000".parse().unwrap(); - - let _result: UnvalidatedProtoEntry = ProtoverVote::compute(&[proto1, proto2], &1); -} - #[test] fn protover_all_supported_should_exclude_versions_we_actually_do_support() { - let proto: UnvalidatedProtoEntry = "Link=3-999".parse().unwrap(); + let proto: UnvalidatedProtoEntry = "Link=3-63".parse().unwrap(); let result: String = proto.all_supported().unwrap().to_string();

- assert_eq!(result, "Link=6-999".to_string()); + assert_eq!(result, "Link=6-63".to_string()); }

#[test] fn protover_all_supported_should_exclude_versions_we_actually_do_support_complex1() { - let proto: UnvalidatedProtoEntry = "Link=1-3,345-666".parse().unwrap(); + let proto: UnvalidatedProtoEntry = "Link=1-3,30-63".parse().unwrap(); let result: String = proto.all_supported().unwrap().to_string();

- assert_eq!(result, "Link=345-666".to_string()); + assert_eq!(result, "Link=30-63".to_string()); }

#[test] @@ -356,26 +346,10 @@ fn protover_all_supported_should_exclude_versions_we_actually_do_support_complex

#[test] fn protover_all_supported_should_exclude_some_versions_and_entire_protocols() { - let proto: UnvalidatedProtoEntry = "Link=1-3,5-12 Quokka=9000-9001".parse().unwrap(); - let result: String = proto.all_supported().unwrap().to_string(); - - assert_eq!(result, "Link=6-12 Quokka=9000-9001".to_string()); -} - -#[test] -fn protover_all_supported_should_not_dos_anyones_computer() { - let proto: UnvalidatedProtoEntry = "Link=1-2147483648".parse().unwrap(); - let result: String = proto.all_supported().unwrap().to_string(); - - assert_eq!(result, "Link=6-2147483648".to_string()); -} - -#[test] -fn protover_all_supported_should_not_dos_anyones_computer_max_versions() { - let proto: UnvalidatedProtoEntry = "Link=1-4294967294".parse().unwrap(); + let proto: UnvalidatedProtoEntry = "Link=1-3,5-12 Quokka=50-51".parse().unwrap(); let result: String = proto.all_supported().unwrap().to_string();

- assert_eq!(result, "Link=6-4294967294".to_string()); + assert_eq!(result, "Link=6-12 Quokka=50-51".to_string()); }

#[test] diff --git a/src/test/test_protover.c b/src/test/test_protover.c index 63c508bd13..b4689045cf 100644 --- a/src/test/test_protover.c +++ b/src/test/test_protover.c @@ -25,7 +25,7 @@ test_protover_parse(void *arg) #else char *re_encoded = NULL;

- const char *orig = "Foo=1,3 Bar=3 Baz= Quux=9-12,14,15-16,900"; + const char *orig = "Foo=1,3 Bar=3 Baz= Quux=9-12,14,15-16"; smartlist_t *elts = parse_protocol_list(orig);

tt_assert(elts); @@ -61,7 +61,7 @@ test_protover_parse(void *arg)

e = smartlist_get(elts, 3); tt_str_op(e->name, OP_EQ, "Quux"); - tt_int_op(smartlist_len(e->ranges), OP_EQ, 4); + tt_int_op(smartlist_len(e->ranges), OP_EQ, 3); { r = smartlist_get(e->ranges, 0); tt_int_op(r->low, OP_EQ, 9); @@ -74,10 +74,6 @@ test_protover_parse(void *arg) r = smartlist_get(e->ranges, 2); tt_int_op(r->low, OP_EQ, 15); tt_int_op(r->high, OP_EQ, 16); - - r = smartlist_get(e->ranges, 3); - tt_int_op(r->low, OP_EQ, 900); - tt_int_op(r->high, OP_EQ, 900); }

re_encoded = encode_protocol_list(elts); @@ -149,14 +145,14 @@ test_protover_vote(void *arg) tt_str_op(result, OP_EQ, ""); tor_free(result);

- smartlist_add(lst, (void*) "Foo=1-10,500 Bar=1,3-7,8"); + smartlist_add(lst, (void*) "Foo=1-10,63 Bar=1,3-7,8"); result = protover_compute_vote(lst, 1); - tt_str_op(result, OP_EQ, "Bar=1,3-8 Foo=1-10,500"); + tt_str_op(result, OP_EQ, "Bar=1,3-8 Foo=1-10,63"); tor_free(result);

- smartlist_add(lst, (void*) "Quux=123-456,78 Bar=2-6,8 Foo=9"); + smartlist_add(lst, (void*) "Quux=12-45 Bar=2-6,8 Foo=9"); result = protover_compute_vote(lst, 1); - tt_str_op(result, OP_EQ, "Bar=1-8 Foo=1-10,500 Quux=78,123-456"); + tt_str_op(result, OP_EQ, "Bar=1-8 Foo=1-10,63 Quux=12-45"); tor_free(result);

result = protover_compute_vote(lst, 2); @@ -194,45 +190,16 @@ test_protover_vote(void *arg)

/* Just below the threshold: Rust */ smartlist_clear(lst); - smartlist_add(lst, (void*) "Sleen=1-500"); + smartlist_add(lst, (void*) "Sleen=1-50"); result = protover_compute_vote(lst, 1); - tt_str_op(result, OP_EQ, "Sleen=1-500"); + tt_str_op(result, OP_EQ, "Sleen=1-50"); tor_free(result);

/* Just below the threshold: C */ smartlist_clear(lst); - smartlist_add(lst, (void*) "Sleen=1-65536"); - result = protover_compute_vote(lst, 1); - tt_str_op(result, OP_EQ, "Sleen=1-65536"); - tor_free(result); - - /* Large protover lists that exceed the threshold */ - - /* By adding two votes, C allows us to exceed the limit */ - smartlist_add(lst, (void*) "Sleen=1-65536"); - smartlist_add(lst, (void*) "Sleen=100000"); - result = protover_compute_vote(lst, 1); - tt_str_op(result, OP_EQ, "Sleen=1-65536,100000"); - tor_free(result); - - /* Large integers */ - smartlist_clear(lst); - smartlist_add(lst, (void*) "Sleen=4294967294"); + smartlist_add(lst, (void*) "Sleen=1-63"); result = protover_compute_vote(lst, 1); - tt_str_op(result, OP_EQ, "Sleen=4294967294"); - tor_free(result); - - /* This parses, but fails at the vote stage */ - smartlist_clear(lst); - smartlist_add(lst, (void*) "Sleen=4294967295"); - result = protover_compute_vote(lst, 1); - tt_str_op(result, OP_EQ, ""); - tor_free(result); - - smartlist_clear(lst); - smartlist_add(lst, (void*) "Sleen=4294967296"); - result = protover_compute_vote(lst, 1); - tt_str_op(result, OP_EQ, ""); + tt_str_op(result, OP_EQ, "Sleen=1-63"); tor_free(result);

/* Protocol name too long */ @@ -272,8 +239,8 @@ test_protover_all_supported(void *arg) tt_assert(! protover_all_supported("Wombat=9", &msg)); tt_str_op(msg, OP_EQ, "Wombat=9"); tor_free(msg); - tt_assert(! protover_all_supported("Link=999", &msg)); - tt_str_op(msg, OP_EQ, "Link=999"); + tt_assert(! protover_all_supported("Link=60", &msg)); + tt_str_op(msg, OP_EQ, "Link=60"); tor_free(msg);

// Mix of things we support and things we don't @@ -283,11 +250,11 @@ test_protover_all_supported(void *arg)

/* Mix of things we support and don't support within a single protocol * which we do support */ - tt_assert(! protover_all_supported("Link=3-999", &msg)); - tt_str_op(msg, OP_EQ, "Link=6-999"); + tt_assert(! protover_all_supported("Link=3-60", &msg)); + tt_str_op(msg, OP_EQ, "Link=6-60"); tor_free(msg); - tt_assert(! protover_all_supported("Link=1-3,345-666", &msg)); - tt_str_op(msg, OP_EQ, "Link=345-666"); + tt_assert(! protover_all_supported("Link=1-3,50-63", &msg)); + tt_str_op(msg, OP_EQ, "Link=50-63"); tor_free(msg); tt_assert(! protover_all_supported("Link=1-3,5-12", &msg)); tt_str_op(msg, OP_EQ, "Link=6-12"); @@ -295,18 +262,8 @@ test_protover_all_supported(void *arg)

/* Mix of protocols we do support and some we don't, where the protocols * we do support have some versions we don't support. */ - tt_assert(! protover_all_supported("Link=1-3,5-12 Quokka=9000-9001", &msg)); - tt_str_op(msg, OP_EQ, "Link=6-12 Quokka=9000-9001"); - tor_free(msg); - - /* We shouldn't be able to DoS ourselves parsing a large range. */ - tt_assert(! protover_all_supported("Sleen=1-2147483648", &msg)); - tt_str_op(msg, OP_EQ, "Sleen=1-2147483648"); - tor_free(msg); - - /* This case is allowed. */ - tt_assert(! protover_all_supported("Sleen=1-4294967294", &msg)); - tt_str_op(msg, OP_EQ, "Sleen=1-4294967294"); + tt_assert(! protover_all_supported("Link=1-3,5-12 Quokka=40-41", &msg)); + tt_str_op(msg, OP_EQ, "Link=6-12 Quokka=40-41"); tor_free(msg);

/* If we get a (barely) valid (but unsupported list, we say "yes, that's @@ -566,9 +523,9 @@ test_protover_vote_roundtrip(void *args) /* Will fail because of 4294967295. */ { "Foo=1,3 Bar=3 Baz= Quux=9-12,14,15-16,900 Zn=1,4294967295", NULL }, - { "Foo=1,3 Bar=3 Baz= Quux=9-12,14,15-16,900 Zn=1,4294967294", - "Bar=3 Foo=1,3 Quux=9-12,14-16,900 Zn=1,4294967294" }, - { "Zu16=1,65536", "Zu16=1,65536" }, + { "Foo=1,3 Bar=3 Baz= Quux=9-12,14,15-16,50 Zn=1,42", + "Bar=3 Foo=1,3 Quux=9-12,14-16,50 Zn=1,42" }, + { "Zu16=1,63", "Zu16=1,63" }, { "N-1=1,2", "N-1=1-2" }, { "-1=4294967295", NULL }, { "-1=3", "-1=3" }, @@ -602,12 +559,8 @@ test_protover_vote_roundtrip(void *args) /* Large integers */ { "Link=4294967296", NULL }, /* Large range */ - { "Sleen=1-501", "Sleen=1-501" }, + { "Sleen=1-63", "Sleen=1-63" }, { "Sleen=1-65537", NULL }, - /* Both C/Rust implementations should be able to handle this mild DoS. */ - { "Sleen=1-2147483648", NULL }, - /* Rust tests are built in debug mode, so ints are bounds-checked. */ - { "Sleen=1-4294967295", NULL }, }; unsigned u; smartlist_t *votes = smartlist_new();