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Add partial support for SSH known hosts markers #11635
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The SSH `known_hosts` file parsing in Cargo did not previously support markers. Markers are modifiers on the lines (`@cert-authority` and `@revoked`) which denote special behavior for the details on that line. Lines were skipped entirely. This silent skipping of marker lines can be confusing to a user, who sees that their command line Git/SSH client works for some repository, but Cargo reports that no host key is found. This change adds support for the `@revoked` marker. This marker denotes that a key should be rejected outright. It is of limited use without `@cert-authority` marker support. However, if it is present in a user's `known_hosts` file, then Cargo definitely shouldn't accept that key and probably shouldn't suggest that the user add it to their `known_hosts` either. The change also adds support for detecting `@cert-authority` markers in `known_hosts` files. These lines cannot yet be used for host key verification, but if one is found for a matching host, the user will be informed that Cargo doesn't support `@cert-authority` markers in the error message. Additionally, the user will be advised to use the `net.git-fetch-with-cli` config option to use the command line git client for fetching crates from Git. Refs: rust-lang#11577
r? @ehuss (rustbot has picked a reviewer for you, use r? to override) |
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Thanks, this looks great! I only have some very minor style nits.
BTW, regarding this:
We're working on that on the git2 side. |
Co-authored-by: Eric Huss <eric@huss.org>
That's fantastic! |
src/cargo/sources/git/known_hosts.rs
Outdated
if key_matches { | ||
return Ok(()); | ||
} |
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I believe there is an issue here. This should not early return on a key match. Otherwise the known_hosts file becomes order-dependent, particularly if the revoked key is found later in a file. I think this should only return until after all entries have been processed.
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You're completely right. Nice catch!
I've fixed the issue and added a test for this case for good measure.
…n processed Since a @Revoked line might deny access to a key which would otherwise be accepted, we need to process all lines before we decide that a host key should be accepted.
…sh-known-hosts-markers
src/cargo/sources/git/known_hosts.rs
Outdated
if key_matches { | ||
accepted_known_host_found = true; | ||
} | ||
|
||
// The host and key type matched, but the key itself did not. | ||
// This indicates the key has changed. | ||
// This is only reported as an error if no subsequent lines have a | ||
// correct key. | ||
latent_errors.push(KnownHostError::HostKeyHasChanged { | ||
hostname: host.to_string(), | ||
key_type: remote_key_type, | ||
old_known_host: known_host.clone(), | ||
remote_host_key: remote_host_key_encoded.clone(), | ||
remote_fingerprint: remote_fingerprint.clone(), | ||
}); |
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I think the latent_errors
part should be in an else block. Otherwise a matching entry will always add a latent error. Although that won't cause any harm as it is written now, I think it would be good to avoid adding an incorrect error object.
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You're right. I'm sorry about that, I made that last change without thinking enough it seems. I've fixed this as suggested now.
Thanks! @bors r+ |
☀️ Test successful - checks-actions |
12 commits in e84a7928d93a31f284b497c214a2ece69b4d7719..82c3bb79e3a19a5164e33819ef81bfc2c984bc56 2023-01-31 22:18:09 +0000 to 2023-02-04 22:52:16 +0000 - util toml targets: Do not infer directory as a file (rust-lang/cargo#11678) - Add more guidance on how to implement unstable features (rust-lang/cargo#11675) - Fix unstable chapter layout for codegen-backend (rust-lang/cargo#11676) - refactor: mod.rs over "name".rs for consistency (rust-lang/cargo#11673) - Verify source before recompile (rust-lang/cargo#11672) - doc: more doc comments and intra-doc links (rust-lang/cargo#11669) - Turn off debuginfo for build dependencies v2 (rust-lang/cargo#11252) - config: Deny CARGO_HOME in [env] table (fixes rust-lang/cargo#11590) (rust-lang/cargo#11644) - Fix the wrong comment (rust-lang/cargo#11651) - Add partial support for SSH known hosts markers (rust-lang/cargo#11635) - Replace `winapi` with `windows-sys` crate. (rust-lang/cargo#11656) - Handle .cargo-ok being truncated (rust-lang/cargo#11665)
Update cargo 12 commits in e84a7928d93a31f284b497c214a2ece69b4d7719..82c3bb79e3a19a5164e33819ef81bfc2c984bc56 2023-01-31 22:18:09 +0000 to 2023-02-04 22:52:16 +0000 - util toml targets: Do not infer directory as a file (rust-lang/cargo#11678) - Add more guidance on how to implement unstable features (rust-lang/cargo#11675) - Fix unstable chapter layout for codegen-backend (rust-lang/cargo#11676) - refactor: mod.rs over "name".rs for consistency (rust-lang/cargo#11673) - Verify source before recompile (rust-lang/cargo#11672) - doc: more doc comments and intra-doc links (rust-lang/cargo#11669) - Turn off debuginfo for build dependencies v2 (rust-lang/cargo#11252) - config: Deny CARGO_HOME in [env] table (fixes rust-lang/cargo#11590) (rust-lang/cargo#11644) - Fix the wrong comment (rust-lang/cargo#11651) - Add partial support for SSH known hosts markers (rust-lang/cargo#11635) - Replace `winapi` with `windows-sys` crate. (rust-lang/cargo#11656) - Handle .cargo-ok being truncated (rust-lang/cargo#11665) r? `@ghost`
Update cargo 12 commits in e84a7928d93a31f284b497c214a2ece69b4d7719..82c3bb79e3a19a5164e33819ef81bfc2c984bc56 2023-01-31 22:18:09 +0000 to 2023-02-04 22:52:16 +0000 - util toml targets: Do not infer directory as a file (rust-lang/cargo#11678) - Add more guidance on how to implement unstable features (rust-lang/cargo#11675) - Fix unstable chapter layout for codegen-backend (rust-lang/cargo#11676) - refactor: mod.rs over "name".rs for consistency (rust-lang/cargo#11673) - Verify source before recompile (rust-lang/cargo#11672) - doc: more doc comments and intra-doc links (rust-lang/cargo#11669) - Turn off debuginfo for build dependencies v2 (rust-lang/cargo#11252) - config: Deny CARGO_HOME in [env] table (fixes rust-lang/cargo#11590) (rust-lang/cargo#11644) - Fix the wrong comment (rust-lang/cargo#11651) - Add partial support for SSH known hosts markers (rust-lang/cargo#11635) - Replace `winapi` with `windows-sys` crate. (rust-lang/cargo#11656) - Handle .cargo-ok being truncated (rust-lang/cargo#11665) r? `@ghost`
Add partial support for SSH known hosts markers ### What does this PR try to resolve? The SSH `known_hosts` file parsing in Cargo did not previously support markers. Markers are modifiers on the lines (``@cert-authority`` and ``@revoked`)` which denote special behavior for the details on that line. Lines were skipped entirely. This silent skipping of marker lines can be confusing to a user, who sees that their command line Git/SSH client works for some repository, but Cargo reports that no host key is found. This change adds support for the ``@revoked`` marker. This marker denotes that a key should be rejected outright. It is of limited use without ``@cert-authority`` marker support. However, if it is present in a user's `known_hosts` file, then Cargo definitely shouldn't accept that key and probably shouldn't suggest that the user add it to their `known_hosts` either. The change also adds support for detecting ``@cert-authority`` markers in `known_hosts` files. These lines cannot yet be used for host key verification, but if one is found for a matching host, the user will be informed that Cargo doesn't support ``@cert-authority`` markers in the error message. Additionally, the user will be advised to use the `net.git-fetch-with-cli` config option to use the command line git client for fetching crates from Git. Refs: rust-lang#11577 ### How should we test and review this PR? The changes in this PR are covered by unit tests, all within `src/cargo/sources/git/known_hosts.rs`. Additionally, manual testing can be performed. For this you will need an OpenSSH server (it doesn't need to be a Git server). I'll assume that you have one running on your local machine at `127.0.0.1`. #### Setup 1. Create a new Cargo project and add the following line to `[dependencies]`: ```toml fake-crate = { git = "ssh://127.0.0.1/fake-crate.git" } ``` #### Test missing host key: `HostKeyNotFound` (existing functionality) 1. Back up your `known_hosts` file and then remove any lines for `127.0.0.1`. 2. Verify host key not present: `ssh 127.0.0.1`. SSH should tell you `The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.` 3. Run `cargo build` 4. Expect error from Cargo: `error: unknown SSH host key` #### Test ``@revoked`` key: `HostKeyRevoked` 1. Back up your `known_hosts` file and then remove any lines for `127.0.0.1`. 2. Add host key: `ssh 127.0.0.1` answer `yes` 3. Find all lines in `known_hosts` beginning with `127.0.0.1` (there may be multiple). 4. Add ``@revoked` ` to the beginning of all lines in (3) 5. Run `cargo build` 6. Expect error from Cargo: error: Key has been revoked for `127.0.0.1` #### Test `@cert-authority`` (not being supported): `HostHasOnlyCertAuthority` 1. Back up your `known_hosts` file and then remove any lines for `127.0.0.1`. 2. Run `cargo build` 3. Expect error from Cargo: `error: unknown SSH host key` 4. Check the line after ` The key to add is:` in the error message and copy the key type (e.g. `ecdsa-sha2-nistp256`) 5. Add a line to `known_hosts`: ``@cert-authority` 127.0.0.1 <key-type> AAAAB5Wm` (e.g. ``@cert-authority` 127.0.0.1 ecdsa-sha2-nistp256 AAAAB5Wm`) 7. Run `cargo build` 8. Expect error from Cargo: error: Found a ``@cert-authority`` marker for `127.0.0.1` ### Additional information Cargo doesn't currently support a few things when checking host keys. This may affect the testing described above. * Multiple host key types (OpenSSH negotiates the host key type and can support matching the one present in the `known_hosts` file even when it's not the preferred type of the server). * Wildcard matching of host patterns (there's a FIXME for this) More information about SSH known host markers can be found on rust-lang#11577.
Note that this will be included in the upcoming Rust 1.68.2 point release, scheduled for 2023-03-28, as it's a prerequisite for #11889. |
[stable] Prepare Rust 1.68.2 This PR prepares the 1.68.2 point release, including the following Cargo PRs: * rust-lang/cargo#11883 * rust-lang/cargo#11889 The following PR was also included as a pre-requisite for backporting: * rust-lang/cargo#11635 cc `@rust-lang/release` r? `@ghost`
Pkgsrc changes: * Adjust patches (add & remove) and cargo checksums to new versions. * It's conceivable that the workaround for LLVM based NetBSD works even less in this version (ref. PKGSRC_HAVE_LIBCPP not having a corresponding patch anymore). Upstream changes: Version 1.68.2 (2023-03-28) =========================== - [Update the GitHub RSA host key bundled within Cargo] (rust-lang/cargo#11883). The key was [rotated by GitHub] (https://github.blog/2023-03-23-we-updated-our-rsa-ssh-host-key/) on 2023-03-24 after the old one leaked. - [Mark the old GitHub RSA host key as revoked] (rust-lang/cargo#11889). This will prevent Cargo from accepting the leaked key even when trusted by the system. - [Add support for `@revoked` and a better error message for `@cert-authority` in Cargo's SSH host key verification] (rust-lang/cargo#11635) Version 1.68.1 (2023-03-23) =========================== - [Fix miscompilation in produced Windows MSVC artifacts] (rust-lang/rust#109094) This was introduced by enabling ThinLTO for the distributed rustc which led to miscompilations in the resulting binary. Currently this is believed to be limited to the -Zdylib-lto flag used for rustc compilation, rather than a general bug in ThinLTO, so only rustc artifacts should be affected. - [Fix --enable-local-rust builds] (rust-lang/rust#109111) - [Treat `$prefix-clang` as `clang` in linker detection code] (rust-lang/rust#109156) - [Fix panic in compiler code] (rust-lang/rust#108162) Version 1.68.0 (2023-03-09) =========================== Language -------- - [Stabilize default_alloc_error_handler] (rust-lang/rust#102318) This allows usage of `alloc` on stable without requiring the definition of a handler for allocation failure. Defining custom handlers is still unstable. - [Stabilize `efiapi` calling convention.] (rust-lang/rust#105795) - [Remove implicit promotion for types with drop glue] (rust-lang/rust#105085) Compiler -------- - [Change `bindings_with_variant_name` to deny-by-default] (rust-lang/rust#104154) - [Allow .. to be parsed as let initializer] (rust-lang/rust#105701) - [Add `armv7-sony-vita-newlibeabihf` as a tier 3 target] (rust-lang/rust#105712) - [Always check alignment during compile-time const evaluation] (rust-lang/rust#104616) - [Disable "split dwarf inlining" by default.] (rust-lang/rust#106709) - [Add vendor to Fuchsia's target triple] (rust-lang/rust#106429) - [Enable sanitizers for s390x-linux] (rust-lang/rust#107127) Libraries --------- - [Loosen the bound on the Debug implementation of Weak.] (rust-lang/rust#90291) - [Make `std::task::Context` !Send and !Sync] (rust-lang/rust#95985) - [PhantomData layout guarantees] (rust-lang/rust#104081) - [Don't derive Debug for `OnceWith` & `RepeatWith`] (rust-lang/rust#104163) - [Implement DerefMut for PathBuf] (rust-lang/rust#105018) - [Add O(1) `Vec -> VecDeque` conversion guarantee] (rust-lang/rust#105128) - [Leak amplification for peek_mut() to ensure BinaryHeap's invariant is always met] (rust-lang/rust#105851) Stabilized APIs --------------- - [`{core,std}::pin::pin!`] (https://doc.rust-lang.org/stable/std/pin/macro.pin.html) - [`impl From<bool> for {f32,f64}`] (https://doc.rust-lang.org/stable/std/primitive.f32.html#impl-From%3Cbool%3E-for-f32) - [`std::path::MAIN_SEPARATOR_STR`] (https://doc.rust-lang.org/stable/std/path/constant.MAIN_SEPARATOR_STR.html) - [`impl DerefMut for PathBuf`] (https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#impl-DerefMut-for-PathBuf) These APIs are now stable in const contexts: - [`VecDeque::new`] (https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.new) Cargo ----- - [Stabilize sparse registry support for crates.io] (rust-lang/cargo#11224) - [`cargo build --verbose` tells you more about why it recompiles.] (rust-lang/cargo#11407) - [Show progress of crates.io index update even `net.git-fetch-with-cli` option enabled] (rust-lang/cargo#11579) Misc ---- Compatibility Notes ------------------- - [Add `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` to future-incompat report] (rust-lang/rust#103418) - [Only specify `--target` by default for `-Zgcc-ld=lld` on wasm] (rust-lang/rust#101792) - [Bump `IMPLIED_BOUNDS_ENTAILMENT` to Deny + ReportNow] (rust-lang/rust#106465) - [`std::task::Context` no longer implements Send and Sync] (rust-lang/rust#95985) nternal Changes ---------------- These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. - [Encode spans relative to the enclosing item] (rust-lang/rust#84762) - [Don't normalize in AstConv] (rust-lang/rust#101947) - [Find the right lower bound region in the scenario of partial order relations] (rust-lang/rust#104765) - [Fix impl block in const expr] (rust-lang/rust#104889) - [Check ADT fields for copy implementations considering regions] (rust-lang/rust#105102) - [rustdoc: simplify JS search routine by not messing with lev distance] (rust-lang/rust#105796) - [Enable ThinLTO for rustc on `x86_64-pc-windows-msvc`] (rust-lang/rust#103591) - [Enable ThinLTO for rustc on `x86_64-apple-darwin`] (rust-lang/rust#103647) Version 1.67.0 (2023-01-26) ========================== Language -------- - [Make `Sized` predicates coinductive, allowing cycles.] (rust-lang/rust#100386) - [`#[must_use]` annotations on `async fn` also affect the `Future::Output`.] (rust-lang/rust#100633) - [Elaborate supertrait obligations when deducing closure signatures.] (rust-lang/rust#101834) - [Invalid literals are no longer an error under `cfg(FALSE)`.] (rust-lang/rust#102944) - [Unreserve braced enum variants in value namespace.] (rust-lang/rust#103578) Compiler -------- - [Enable varargs support for calling conventions other than `C` or `cdecl`.] (rust-lang/rust#97971) - [Add new MIR constant propagation based on dataflow analysis.] (rust-lang/rust#101168) - [Optimize field ordering by grouping m\*2^n-sized fields with equivalently aligned ones.] (rust-lang/rust#102750) - [Stabilize native library modifier `verbatim`.] (rust-lang/rust#104360) Added and removed targets: - [Add a tier 3 target for PowerPC on AIX] (rust-lang/rust#102293), `powerpc64-ibm-aix`. - [Add a tier 3 target for the Sony PlayStation 1] (rust-lang/rust#102689), `mipsel-sony-psx`. - [Add tier 3 `no_std` targets for the QNX Neutrino RTOS] (rust-lang/rust#102701), `aarch64-unknown-nto-qnx710` and `x86_64-pc-nto-qnx710`. - [Remove tier 3 `linuxkernel` targets] (rust-lang/rust#104015) (not used by the actual kernel). Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Merge `crossbeam-channel` into `std::sync::mpsc`.] (rust-lang/rust#93563) - [Fix inconsistent rounding of 0.5 when formatted to 0 decimal places.] (rust-lang/rust#102935) - [Derive `Eq` and `Hash` for `ControlFlow`.] (rust-lang/rust#103084) - [Don't build `compiler_builtins` with `-C panic=abort`.] (rust-lang/rust#103786) Stabilized APIs --------------- - [`{integer}::checked_ilog`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.checked_ilog) - [`{integer}::checked_ilog2`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.checked_ilog2) - [`{integer}::checked_ilog10`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.checked_ilog10) - [`{integer}::ilog`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.ilog) - [`{integer}::ilog2`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.ilog2) - [`{integer}::ilog10`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.ilog10) - [`NonZeroU*::ilog2`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroU32.html#method.ilog2) - [`NonZeroU*::ilog10`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroU32.html#method.ilog10) - [`NonZero*::BITS`] (https://doc.rust-lang.org/stable/std/num/struct.NonZeroU32.html#associatedconstant.BITS) These APIs are now stable in const contexts: - [`char::from_u32`] (https://doc.rust-lang.org/stable/std/primitive.char.html#method.from_u32) - [`char::from_digit`] (https://doc.rust-lang.org/stable/std/primitive.char.html#method.from_digit) - [`char::to_digit`] (https://doc.rust-lang.org/stable/std/primitive.char.html#method.to_digit) - [`core::char::from_u32`] (https://doc.rust-lang.org/stable/core/char/fn.from_u32.html) - [`core::char::from_digit`] (https://doc.rust-lang.org/stable/core/char/fn.from_digit.html) Compatibility Notes ------------------- - [The layout of `repr(Rust)` types now groups m\*2^n-sized fields with equivalently aligned ones.] (rust-lang/rust#102750) This is intended to be an optimization, but it is also known to increase type sizes in a few cases for the placement of enum tags. As a reminder, the layout of `repr(Rust)` types is an implementation detail, subject to change. - [0.5 now rounds to 0 when formatted to 0 decimal places.] (rust-lang/rust#102935) This makes it consistent with the rest of floating point formatting that rounds ties toward even digits. - [Chains of `&&` and `||` will now drop temporaries from their sub-expressions in evaluation order, left-to-right.] (rust-lang/rust#103293) Previously, it was "twisted" such that the _first_ expression dropped its temporaries _last_, after all of the other expressions dropped in order. - [Underscore suffixes on string literals are now a hard error.] (rust-lang/rust#103914) This has been a future-compatibility warning since 1.20.0. - [Stop passing `-export-dynamic` to `wasm-ld`.] (rust-lang/rust#105405) - [`main` is now mangled as `__main_void` on `wasm32-wasi`.] (rust-lang/rust#105468) - [Cargo now emits an error if there are multiple registries in the configuration with the same index URL.] (rust-lang/cargo#10592) Internal Changes ---------------- These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. - [Rewrite LLVM's archive writer in Rust.] (rust-lang/rust#97485)
What does this PR try to resolve?
The SSH
known_hosts
file parsing in Cargo did not previously supportmarkers. Markers are modifiers on the lines (
@cert-authority
and@revoked
) which denote special behavior for the details on that line.Lines were skipped entirely.
This silent skipping of marker lines can be confusing to a user, who
sees that their command line Git/SSH client works for some repository,
but Cargo reports that no host key is found.
This change adds support for the
@revoked
marker. This marker denotesthat a key should be rejected outright. It is of limited use without
@cert-authority
marker support. However, if it is present in a user'sknown_hosts
file, then Cargo definitely shouldn't accept that key andprobably shouldn't suggest that the user add it to their
known_hosts
either.
The change also adds support for detecting
@cert-authority
markers inknown_hosts
files. These lines cannot yet be used for host keyverification, but if one is found for a matching host, the user will be
informed that Cargo doesn't support
@cert-authority
markers in theerror message. Additionally, the user will be advised to use the
net.git-fetch-with-cli
config option to use the command line gitclient for fetching crates from Git.
Refs: #11577
How should we test and review this PR?
The changes in this PR are covered by unit tests, all within
src/cargo/sources/git/known_hosts.rs
.Additionally, manual testing can be performed. For this you will need
an OpenSSH server (it doesn't need to be a Git server). I'll assume
that you have one running on your local machine at
127.0.0.1
.Setup
[dependencies]
:Test missing host key:
HostKeyNotFound
(existing functionality)known_hosts
file and then remove any lines for127.0.0.1
.ssh 127.0.0.1
. SSH should tell youThe authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.
cargo build
error: unknown SSH host key
Test
@revoked
key:HostKeyRevoked
known_hosts
file and then remove any lines for127.0.0.1
.ssh 127.0.0.1
answeryes
known_hosts
beginning with127.0.0.1
(there may be multiple).@revoked
to the beginning of all lines in (3)cargo build
127.0.0.1
Test @cert-authority
(not being supported):
HostHasOnlyCertAuthority`known_hosts
file and then remove any lines for127.0.0.1
.cargo build
error: unknown SSH host key
The key to add is:
in the error message and copy the key type (e.g.ecdsa-sha2-nistp256
)known_hosts
:@cert-authority 127.0.0.1 <key-type> AAAAB5Wm
(e.g.@cert-authority 127.0.0.1 ecdsa-sha2-nistp256 AAAAB5Wm
)cargo build
@cert-authority
marker for127.0.0.1
Additional information
Cargo doesn't currently support a few things when checking host keys. This may affect the testing described above.
known_hosts
file even when it's not the preferred type of the server).More information about SSH known host markers can be found
on #11577.