mirror of
https://github.com/kata-containers/kata-containers.git
synced 2025-04-28 19:54:35 +00:00
libs/safe-path: add crate to safely resolve fs paths
There are always path(symlink) based attacks, so the `safe-path` crate tries to provde some mechanisms to harden path resolution related code. Fixes: #3451 Signed-off-by: Liu Jiang <gerry@linux.alibaba.com>
This commit is contained in:
Liu Jiang
parent
baa67d8cc5
commit
b63774ec61
@ -118,6 +118,7 @@ The table below lists the core parts of the project:
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| [runtime](src/runtime) | core | Main component run by a container manager and providing a containerd shimv2 runtime implementation. |
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| [agent](src/agent) | core | Management process running inside the virtual machine / POD that sets up the container environment. |
|
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| [documentation](docs) | documentation | Documentation common to all components (such as design and install documentation). |
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| [libraries](src/libs) | core | Library crates shared by multiple Kata Container components or published to [`crates.io`](https://crates.io/index.html) |
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| [tests](https://github.com/kata-containers/tests) | tests | Excludes unit tests which live with the main code. |
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|
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### Additional components
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108
src/libs/logging/Cargo.lock → src/libs/Cargo.lock
generated
108
src/libs/logging/Cargo.lock → src/libs/Cargo.lock
generated
@ -1,7 +1,5 @@
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# This file is automatically @generated by Cargo.
|
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# It is not intended for manual editing.
|
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version = 3
|
||||
|
||||
[[package]]
|
||||
name = "arc-swap"
|
||||
version = "1.5.0"
|
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@ -41,9 +39,9 @@ dependencies = [
|
||||
|
||||
[[package]]
|
||||
name = "crossbeam-channel"
|
||||
version = "0.5.1"
|
||||
version = "0.5.2"
|
||||
source = "registry+https://github.com/rust-lang/crates.io-index"
|
||||
checksum = "06ed27e177f16d65f0f0c22a213e17c696ace5dd64b14258b52f9417ccb52db4"
|
||||
checksum = "e54ea8bc3fb1ee042f5aace6e3c6e025d3874866da222930f70ce62aceba0bfa"
|
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dependencies = [
|
||||
"cfg-if",
|
||||
"crossbeam-utils",
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@ -51,23 +49,30 @@ dependencies = [
|
||||
|
||||
[[package]]
|
||||
name = "crossbeam-utils"
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||||
version = "0.8.5"
|
||||
version = "0.8.6"
|
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "d82cfc11ce7f2c3faef78d8a684447b40d503d9681acebed6cb728d45940c4db"
|
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checksum = "cfcae03edb34f947e64acdb1c33ec169824e20657e9ecb61cef6c8c74dcb8120"
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dependencies = [
|
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"cfg-if",
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"lazy_static",
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]
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[[package]]
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name = "getrandom"
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version = "0.2.3"
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name = "fastrand"
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version = "1.6.0"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "7fcd999463524c52659517fe2cea98493cfe485d10565e7b0fb07dbba7ad2753"
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checksum = "779d043b6a0b90cc4c0ed7ee380a6504394cee7efd7db050e3774eee387324b2"
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dependencies = [
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"instant",
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]
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[[package]]
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name = "instant"
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version = "0.1.12"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "7a5bbe824c507c5da5956355e86a746d82e0e1464f65d862cc5e71da70e94b2c"
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dependencies = [
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"cfg-if",
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"libc",
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"wasi",
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]
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[[package]]
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@ -84,9 +89,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
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[[package]]
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name = "libc"
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version = "0.2.112"
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version = "0.2.113"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "1b03d17f364a3a042d5e5d46b053bbbf82c92c9430c592dd4c064dc6ee997125"
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checksum = "eef78b64d87775463c549fbd80e19249ef436ea3bf1de2a1eb7e717ec7fab1e9"
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[[package]]
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name = "logging"
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@ -125,52 +130,6 @@ version = "1.9.0"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "da32515d9f6e6e489d7bc9d84c71b060db7247dc035bbe44eac88cf87486d8d5"
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[[package]]
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name = "ppv-lite86"
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version = "0.2.15"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "ed0cfbc8191465bed66e1718596ee0b0b35d5ee1f41c5df2189d0fe8bde535ba"
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[[package]]
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name = "rand"
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version = "0.8.4"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "2e7573632e6454cf6b99d7aac4ccca54be06da05aca2ef7423d22d27d4d4bcd8"
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dependencies = [
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"libc",
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"rand_chacha",
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"rand_core",
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"rand_hc",
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]
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[[package]]
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name = "rand_chacha"
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version = "0.3.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
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dependencies = [
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"ppv-lite86",
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"rand_core",
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]
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[[package]]
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name = "rand_core"
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version = "0.6.3"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "d34f1408f55294453790c48b2f1ebbb1c5b4b7563eb1f418bcfcfdbb06ebb4e7"
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dependencies = [
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"getrandom",
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]
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[[package]]
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name = "rand_hc"
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version = "0.3.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "d51e9f596de227fda2ea6c84607f5558e196eeaf43c986b724ba4fb8fdf497e7"
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dependencies = [
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"rand_core",
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]
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[[package]]
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name = "redox_syscall"
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version = "0.2.10"
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@ -195,17 +154,25 @@ version = "1.0.9"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "73b4b750c782965c211b42f022f59af1fbceabdd026623714f104152f1ec149f"
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[[package]]
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name = "safe-path"
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version = "0.1.0"
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dependencies = [
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"libc",
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"tempfile",
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]
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[[package]]
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name = "serde"
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version = "1.0.131"
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version = "1.0.133"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "b4ad69dfbd3e45369132cc64e6748c2d65cdfb001a2b1c232d128b4ad60561c1"
|
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checksum = "97565067517b60e2d1ea8b268e59ce036de907ac523ad83a0475da04e818989a"
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[[package]]
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name = "serde_json"
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version = "1.0.73"
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version = "1.0.75"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "bcbd0344bc6533bc7ec56df11d42fb70f1b912351c0825ccb7211b59d8af7cf5"
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checksum = "c059c05b48c5c0067d4b4b2b4f0732dd65feb52daf7e0ea09cd87e7dadc1af79"
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dependencies = [
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"itoa",
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"ryu",
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@ -261,13 +228,13 @@ checksum = "f764005d11ee5f36500a149ace24e00e3da98b0158b3e2d53a7495660d3f4d60"
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[[package]]
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name = "tempfile"
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version = "3.2.0"
|
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version = "3.3.0"
|
||||
source = "registry+https://github.com/rust-lang/crates.io-index"
|
||||
checksum = "dac1c663cfc93810f88aed9b8941d48cabf856a1b111c29a40439018d870eb22"
|
||||
checksum = "5cdb1ef4eaeeaddc8fbd371e5017057064af0911902ef36b39801f67cc6d79e4"
|
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dependencies = [
|
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"cfg-if",
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"fastrand",
|
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"libc",
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"rand",
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"redox_syscall",
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"remove_dir_all",
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"winapi",
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@ -284,19 +251,20 @@ dependencies = [
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[[package]]
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name = "time"
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version = "0.1.43"
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||||
version = "0.1.44"
|
||||
source = "registry+https://github.com/rust-lang/crates.io-index"
|
||||
checksum = "ca8a50ef2360fbd1eeb0ecd46795a87a19024eb4b53c5dc916ca1fd95fe62438"
|
||||
checksum = "6db9e6914ab8b1ae1c260a4ae7a49b6c5611b40328a735b21862567685e73255"
|
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dependencies = [
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"libc",
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"wasi",
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"winapi",
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]
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[[package]]
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name = "wasi"
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version = "0.10.2+wasi-snapshot-preview1"
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version = "0.10.0+wasi-snapshot-preview1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
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checksum = "1a143597ca7c7793eff794def352d41792a93c481eb1042423ff7ff72ba2c31f"
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[[package]]
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name = "winapi"
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6
src/libs/Cargo.toml
Normal file
6
src/libs/Cargo.toml
Normal file
@ -0,0 +1,6 @@
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[workspace]
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members = [
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"logging",
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"safe-path",
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]
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resolver = "2"
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10
src/libs/README.md
Normal file
10
src/libs/README.md
Normal file
@ -0,0 +1,10 @@
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The `src/libs` directory hosts library crates which may be shared by multiple Kata Containers components
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or published to [`crates.io`](https://crates.io/index.html).
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### Library Crates
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Currently it provides following library crates:
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| Library | Description |
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|-|-|-|
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| [logging](logging/) | Facilities to setup logging subsystem based slog. |
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| [safe-path](safe-path/) | Utilities to safely resolve filesystem paths. |
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18
src/libs/safe-path/Cargo.toml
Normal file
18
src/libs/safe-path/Cargo.toml
Normal file
@ -0,0 +1,18 @@
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[package]
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name = "safe-path"
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version = "0.1.0"
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description = "A library to safely handle file system paths for container runtimes"
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keywords = ["kata", "container", "path", "securejoin"]
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categories = ["parser-implementations", "filesystem"]
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authors = ["The Kata Containers community <kata-dev@lists.katacontainers.io>"]
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repository = "https://github.com/kata-containers/kata-containers.git"
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homepage = "https://katacontainers.io/"
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readme = "README.md"
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license = "Apache-2.0"
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edition = "2018"
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[dependencies]
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libc = "0.2.100"
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[dev-dependencies]
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tempfile = "3.2.0"
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21
src/libs/safe-path/README.md
Normal file
21
src/libs/safe-path/README.md
Normal file
@ -0,0 +1,21 @@
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Safe Path
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====================
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[](https://github.com/magiclen/path-absolutize/actions/workflows/ci.yml)
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A library to safely handle filesystem paths, typically for container runtimes.
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There are often path related attacks, such as symlink based attacks, TOCTTOU attacks. The `safe-path` crate
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provides several functions and utility structures to protect against path resolution related attacks.
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## Support
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**Operating Systems**:
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- Linux
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## Reference
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- [`filepath-securejoin`](https://github.com/cyphar/filepath-securejoin): secure_join() written in Go.
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- [CVE-2021-30465](https://github.com/advisories/GHSA-c3xm-pvg7-gh7r): symlink related TOCTOU flaw in `runC`.
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## License
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This code is licensed under [Apache-2.0](../../../LICENSE).
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65
src/libs/safe-path/src/lib.rs
Normal file
65
src/libs/safe-path/src/lib.rs
Normal file
@ -0,0 +1,65 @@
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// Copyright (c) 2022 Alibaba Cloud
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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//! A library to safely handle filesystem paths, typically for container runtimes.
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//!
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//! Linux [mount namespace](https://man7.org/linux/man-pages/man7/mount_namespaces.7.html)
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//! provides isolation of the list of mounts seen by the processes in each
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//! [namespace](https://man7.org/linux/man-pages/man7/namespaces.7.html) instance.
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//! Thus, the processes in each of the mount namespace instances will see distinct single-directory
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//! hierarchies.
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//!
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//! Containers are used to isolate workloads from the host system. Container on Linux systems
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//! depends on the mount namespace to build an isolated root filesystem for each container,
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//! thus protect the host and containers from each other. When creating containers, the container
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//! runtime needs to setup filesystem mounts for container rootfs/volumes. Configuration for
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//! mounts/paths may be indirectly controlled by end users through:
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//! - container images
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//! - Kubernetes pod specifications
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//! - hook command line arguments
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//!
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//! These volume configuration information may be controlled by end users/malicious attackers,
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//! so it must not be trusted by container runtimes. When the container runtime is preparing mount
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//! namespace for a container, it must be very careful to validate user input configuration
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//! information and ensure data out of the container rootfs directory won't be affected
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//! by the container. There are several types of attacks related to container mount namespace:
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//! - symlink based attack
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//! - Time of check to time of use (TOCTTOU)
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//!
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//! This crate provides several mechanisms for container runtimes to safely handle filesystem paths
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//! when preparing mount namespace for containers.
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//! - [scoped_join()](crate::scoped_join()): safely join `unsafe_path` to `root`, and ensure
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//! `unsafe_path` is scoped under `root`.
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//! - [scoped_resolve()](crate::scoped_resolve()): resolve `unsafe_path` to a relative path,
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//! rooted at and constrained by `root`.
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//! - [struct PinnedPathBuf](crate::PinnedPathBuf): safe version of `PathBuf` to protect from
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//! TOCTTOU style of attacks, which ensures:
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//! - the value of [`PinnedPathBuf::as_path()`] never changes.
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//! - the path returned by [`PinnedPathBuf::as_path()`] is always a symlink.
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//! - the filesystem object referenced by the symlink [`PinnedPathBuf::as_path()`] never changes.
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//! - the value of [`PinnedPathBuf::target()`] never changes.
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//! - [struct ScopedDirBuilder](crate::ScopedDirBuilder): safe version of `DirBuilder` to protect
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//! from symlink race and TOCTTOU style of attacks, which enhances security by:
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//! - ensuring the new directories are created under a specified `root` directory.
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||||
//! - avoiding symlink race attacks during making directories.
|
||||
//! - returning a [PinnedPathBuf] for the last level of directory, so it could be used for other
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||||
//! operations safely.
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||||
//!
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||||
//! The work is inspired by:
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||||
//! - [`filepath-securejoin`](https://github.com/cyphar/filepath-securejoin): secure_join() written
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||||
//! in Go.
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||||
//! - [CVE-2021-30465](https://github.com/advisories/GHSA-c3xm-pvg7-gh7r): symlink related TOCTOU
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||||
//! flaw in `runC`.
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#![deny(missing_docs)]
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mod pinned_path_buf;
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pub use pinned_path_buf::PinnedPathBuf;
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mod scoped_dir_builder;
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pub use scoped_dir_builder::ScopedDirBuilder;
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mod scoped_path_resolver;
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||||
pub use scoped_path_resolver::{scoped_join, scoped_resolve};
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400
src/libs/safe-path/src/pinned_path_buf.rs
Normal file
400
src/libs/safe-path/src/pinned_path_buf.rs
Normal file
@ -0,0 +1,400 @@
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||||
// Copyright (c) 2022 Alibaba Cloud
|
||||
//
|
||||
// SPDX-License-Identifier: Apache-2.0
|
||||
//
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||||
|
||||
use std::ffi::{CString, OsStr};
|
||||
use std::fs::{self, File, Metadata, OpenOptions};
|
||||
use std::io::{Error, ErrorKind, Result};
|
||||
use std::ops::Deref;
|
||||
use std::os::unix::ffi::OsStrExt;
|
||||
use std::os::unix::fs::OpenOptionsExt;
|
||||
use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
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||||
use std::path::{Component, Path, PathBuf};
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||||
|
||||
use crate::scoped_join;
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||||
|
||||
/// A safe version of [`PathBuf`] pinned to an underlying filesystem object to protect from
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||||
/// `TOCTTOU` style of attacks.
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||||
///
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||||
/// A [`PinnedPathBuf`] is a resolved path buffer pinned to an underlying filesystem object, which
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/// guarantees:
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/// - the value of [`PinnedPathBuf::as_path()`] never changes.
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/// - the path returned by [`PinnedPathBuf::as_path()`] is always a symlink.
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/// - the filesystem object referenced by the symlink [`PinnedPathBuf::as_path()`] never changes.
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/// - the value of [`PinnedPathBuf::target()`] never changes.
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///
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/// Note:
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/// - Though the filesystem object referenced by the symlink [`PinnedPathBuf::as_path()`] never
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||||
/// changes, the value of `fs::read_link(PinnedPathBuf::as_path())` may change due to filesystem
|
||||
/// operations.
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||||
/// - The value of [`PinnedPathBuf::target()`] is a cached version of
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/// `fs::read_link(PinnedPathBuf::as_path())` generated when creating the `PinnedPathBuf` object.
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||||
/// - It's a sign of possible attacks if `[PinnedPathBuf::target()]` doesn't match
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||||
/// `fs::read_link(PinnedPathBuf::as_path())`.
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||||
/// - Once the [`PinnedPathBuf`] object gets dropped, the [`Path`] returned by
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||||
/// [`PinnedPathBuf::as_path()`] becomes invalid.
|
||||
///
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||||
/// With normal [`PathBuf`], there's a race window for attackers between time to validate a path and
|
||||
/// time to use the path. An attacker may maliciously change filesystem object referenced by the
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||||
/// path by using symlinks to compose an attack.
|
||||
///
|
||||
/// The [`PinnedPathBuf`] is introduced to protect from such attacks, by using the
|
||||
/// `/proc/self/fd/xxx` files on Linux. The `/proc/self/fd/xxx` file on Linux is a symlink to the
|
||||
/// real target corresponding to the process's file descriptor `xxx`. And the target filesystem
|
||||
/// object referenced by the symlink will be kept stable until the file descriptor has been closed.
|
||||
/// Combined with `O_PATH`, a safe version of `PathBuf` could be built by:
|
||||
/// - Generate a safe path from `root` and `path` by using [`crate::scoped_join()`].
|
||||
/// - Open the safe path with O_PATH | O_CLOEXEC flags, say the fd number is `fd_num`.
|
||||
/// - Read the symlink target of `/proc/self/fd/fd_num`.
|
||||
/// - Compare the symlink target with the safe path, it's safe if these two paths equal.
|
||||
/// - Use the proc file path as a safe version of [`PathBuf`].
|
||||
/// - Close the `fd_num` when dropping the [`PinnedPathBuf`] object.
|
||||
#[derive(Debug)]
|
||||
pub struct PinnedPathBuf {
|
||||
handle: File,
|
||||
path: PathBuf,
|
||||
target: PathBuf,
|
||||
}
|
||||
|
||||
impl PinnedPathBuf {
|
||||
/// Create a [`PinnedPathBuf`] object from `root` and `path`.
|
||||
///
|
||||
/// The `path` must be a subdirectory of `root`, otherwise error will be returned.
|
||||
pub fn new<R: AsRef<Path>, U: AsRef<Path>>(root: R, path: U) -> Result<Self> {
|
||||
let path = scoped_join(root, path)?;
|
||||
Self::from_path(path)
|
||||
}
|
||||
|
||||
/// Create a `PinnedPathBuf` from `path`.
|
||||
///
|
||||
/// If the resolved value of `path` doesn't equal to `path`, an error will be returned.
|
||||
pub fn from_path<P: AsRef<Path>>(orig_path: P) -> Result<Self> {
|
||||
let orig_path = orig_path.as_ref();
|
||||
let handle = Self::open_by_path(orig_path)?;
|
||||
Self::new_from_file(handle, orig_path)
|
||||
}
|
||||
|
||||
/// Try to clone the [`PinnedPathBuf`] object.
|
||||
pub fn try_clone(&self) -> Result<Self> {
|
||||
let fd = unsafe { libc::dup(self.path_fd()) };
|
||||
if fd < 0 {
|
||||
Err(Error::last_os_error())
|
||||
} else {
|
||||
Ok(Self {
|
||||
handle: unsafe { File::from_raw_fd(fd) },
|
||||
path: Self::get_proc_path(fd),
|
||||
target: self.target.clone(),
|
||||
})
|
||||
}
|
||||
}
|
||||
|
||||
/// Return the underlying file descriptor representing the pinned path.
|
||||
///
|
||||
/// Following operations are supported by the returned `RawFd`:
|
||||
/// - fchdir
|
||||
/// - fstat/fstatfs
|
||||
/// - openat/linkat/fchownat/fstatat/readlinkat/mkdirat/*at
|
||||
/// - fcntl(F_GETFD, F_SETFD, F_GETFL)
|
||||
pub fn path_fd(&self) -> RawFd {
|
||||
self.handle.as_raw_fd()
|
||||
}
|
||||
|
||||
/// Get the symlink path referring the target filesystem object.
|
||||
pub fn as_path(&self) -> &Path {
|
||||
self.path.as_path()
|
||||
}
|
||||
|
||||
/// Get the cached real path of the target filesystem object.
|
||||
///
|
||||
/// The target path is cached version of `fs::read_link(PinnedPathBuf::as_path())` generated
|
||||
/// when creating the `PinnedPathBuf` object. On the other hand, the value of
|
||||
/// `fs::read_link(PinnedPathBuf::as_path())` may change due to underlying filesystem operations.
|
||||
/// So it's a sign of possible attacks if `PinnedPathBuf::target()` does not match
|
||||
/// `fs::read_link(PinnedPathBuf::as_path())`.
|
||||
pub fn target(&self) -> &Path {
|
||||
&self.target
|
||||
}
|
||||
|
||||
/// Get [`Metadata`] about the path handle.
|
||||
pub fn metadata(&self) -> Result<Metadata> {
|
||||
self.handle.metadata()
|
||||
}
|
||||
|
||||
/// Open a direct child of the filesystem objected referenced by the `PinnedPathBuf` object.
|
||||
pub fn open_child(&self, path_comp: &OsStr) -> Result<Self> {
|
||||
let name = Self::prepare_path_component(path_comp)?;
|
||||
let oflags = libc::O_PATH | libc::O_CLOEXEC;
|
||||
let res = unsafe { libc::openat(self.path_fd(), name.as_ptr(), oflags, 0) };
|
||||
if res < 0 {
|
||||
Err(Error::last_os_error())
|
||||
} else {
|
||||
let handle = unsafe { File::from_raw_fd(res) };
|
||||
Self::new_from_file(handle, self.target.join(path_comp))
|
||||
}
|
||||
}
|
||||
|
||||
/// Create or open a child directory if current object is a directory.
|
||||
pub fn mkdir(&self, path_comp: &OsStr, mode: libc::mode_t) -> Result<Self> {
|
||||
let path_name = Self::prepare_path_component(path_comp)?;
|
||||
let res = unsafe { libc::mkdirat(self.handle.as_raw_fd(), path_name.as_ptr(), mode) };
|
||||
if res < 0 {
|
||||
Err(Error::last_os_error())
|
||||
} else {
|
||||
self.open_child(path_comp)
|
||||
}
|
||||
}
|
||||
|
||||
/// Open a directory/file by path.
|
||||
///
|
||||
/// Obtain a file descriptor that can be used for two purposes:
|
||||
/// - indicate a location in the filesystem tree
|
||||
/// - perform operations that act purely at the file descriptor level
|
||||
fn open_by_path<P: AsRef<Path>>(path: P) -> Result<File> {
|
||||
// When O_PATH is specified in flags, flag bits other than O_CLOEXEC, O_DIRECTORY, and
|
||||
// O_NOFOLLOW are ignored.
|
||||
let o_flags = libc::O_PATH | libc::O_CLOEXEC;
|
||||
OpenOptions::new()
|
||||
.read(true)
|
||||
.custom_flags(o_flags)
|
||||
.open(path.as_ref())
|
||||
}
|
||||
|
||||
fn get_proc_path<F: AsRawFd>(file: F) -> PathBuf {
|
||||
PathBuf::from(format!("/proc/self/fd/{}", file.as_raw_fd()))
|
||||
}
|
||||
|
||||
fn new_from_file<P: AsRef<Path>>(handle: File, orig_path: P) -> Result<Self> {
|
||||
let path = Self::get_proc_path(handle.as_raw_fd());
|
||||
let link_path = fs::read_link(path.as_path())?;
|
||||
if link_path != orig_path.as_ref() {
|
||||
Err(Error::new(
|
||||
ErrorKind::Other,
|
||||
format!(
|
||||
"Path changed from {} to {} on open, possible attack",
|
||||
orig_path.as_ref().display(),
|
||||
link_path.display()
|
||||
),
|
||||
))
|
||||
} else {
|
||||
Ok(PinnedPathBuf {
|
||||
handle,
|
||||
path,
|
||||
target: link_path,
|
||||
})
|
||||
}
|
||||
}
|
||||
|
||||
#[inline]
|
||||
fn prepare_path_component(path_comp: &OsStr) -> Result<CString> {
|
||||
let path = Path::new(path_comp);
|
||||
let mut comps = path.components();
|
||||
let name = comps.next();
|
||||
if !matches!(name, Some(Component::Normal(_))) || comps.next().is_some() {
|
||||
return Err(Error::new(
|
||||
ErrorKind::Other,
|
||||
format!("Path component {} is invalid", path_comp.to_string_lossy()),
|
||||
));
|
||||
}
|
||||
let name = name.unwrap();
|
||||
if name.as_os_str() != path_comp {
|
||||
return Err(Error::new(
|
||||
ErrorKind::Other,
|
||||
format!("Path component {} is invalid", path_comp.to_string_lossy()),
|
||||
));
|
||||
}
|
||||
|
||||
CString::new(path_comp.as_bytes()).map_err(|_e| {
|
||||
Error::new(
|
||||
ErrorKind::Other,
|
||||
format!("Path component {} is invalid", path_comp.to_string_lossy()),
|
||||
)
|
||||
})
|
||||
}
|
||||
}
|
||||
|
||||
impl Deref for PinnedPathBuf {
|
||||
type Target = PathBuf;
|
||||
|
||||
fn deref(&self) -> &Self::Target {
|
||||
&self.path
|
||||
}
|
||||
}
|
||||
|
||||
impl AsRef<Path> for PinnedPathBuf {
|
||||
fn as_ref(&self) -> &Path {
|
||||
self.path.as_path()
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
use std::fs::DirBuilder;
|
||||
use std::io::Write;
|
||||
use std::os::unix::fs::{symlink, MetadataExt};
|
||||
use std::sync::{Arc, Barrier};
|
||||
use std::thread;
|
||||
|
||||
#[test]
|
||||
fn test_pinned_path_buf() {
|
||||
// Create a root directory, which itself contains symlinks.
|
||||
let rootfs_dir = tempfile::tempdir().expect("failed to create tmpdir");
|
||||
DirBuilder::new()
|
||||
.create(rootfs_dir.path().join("b"))
|
||||
.unwrap();
|
||||
symlink(rootfs_dir.path().join("b"), rootfs_dir.path().join("a")).unwrap();
|
||||
let rootfs_path = &rootfs_dir.path().join("a");
|
||||
|
||||
// Create a file and a symlink to it.
|
||||
fs::create_dir(rootfs_path.join("symlink_dir")).unwrap();
|
||||
symlink("/endpoint", rootfs_path.join("symlink_dir/endpoint")).unwrap();
|
||||
fs::write(rootfs_path.join("endpoint"), "test").unwrap();
|
||||
|
||||
// Pin the target and validate the path/content.
|
||||
let path = PinnedPathBuf::new(rootfs_path.to_path_buf(), "symlink_dir/endpoint").unwrap();
|
||||
assert!(!path.is_dir());
|
||||
let path_ref = path.deref();
|
||||
let target = fs::read_link(path_ref).unwrap();
|
||||
assert_eq!(target, rootfs_path.join("endpoint").canonicalize().unwrap());
|
||||
let content = fs::read_to_string(&path).unwrap();
|
||||
assert_eq!(&content, "test");
|
||||
|
||||
// Remove the target file and validate that we could still read data from the pinned path.
|
||||
fs::remove_file(&target).unwrap();
|
||||
fs::read_to_string(&target).unwrap_err();
|
||||
let content = fs::read_to_string(&path).unwrap();
|
||||
assert_eq!(&content, "test");
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_pinned_path_buf_race() {
|
||||
let root_dir = tempfile::tempdir().expect("failed to create tmpdir");
|
||||
let root_path = root_dir.path();
|
||||
let barrier = Arc::new(Barrier::new(2));
|
||||
|
||||
fs::write(root_path.join("a"), b"a").unwrap();
|
||||
fs::write(root_path.join("b"), b"b").unwrap();
|
||||
fs::write(root_path.join("c"), b"c").unwrap();
|
||||
symlink("a", root_path.join("s")).unwrap();
|
||||
|
||||
let root_path2 = root_path.to_path_buf();
|
||||
let barrier2 = barrier.clone();
|
||||
let thread = thread::spawn(move || {
|
||||
// step 1
|
||||
barrier2.wait();
|
||||
fs::remove_file(root_path2.join("a")).unwrap();
|
||||
symlink("b", root_path2.join("a")).unwrap();
|
||||
barrier2.wait();
|
||||
|
||||
// step 2
|
||||
barrier2.wait();
|
||||
fs::remove_file(root_path2.join("b")).unwrap();
|
||||
symlink("c", root_path2.join("b")).unwrap();
|
||||
barrier2.wait();
|
||||
});
|
||||
|
||||
let path = scoped_join(&root_path, "s").unwrap();
|
||||
let data = fs::read_to_string(&path).unwrap();
|
||||
assert_eq!(&data, "a");
|
||||
assert!(path.is_file());
|
||||
barrier.wait();
|
||||
barrier.wait();
|
||||
// Verify the target has been redirected.
|
||||
let data = fs::read_to_string(&path).unwrap();
|
||||
assert_eq!(&data, "b");
|
||||
PinnedPathBuf::from_path(&path).unwrap_err();
|
||||
|
||||
let pinned_path = PinnedPathBuf::new(&root_path, "s").unwrap();
|
||||
let data = fs::read_to_string(&pinned_path).unwrap();
|
||||
assert_eq!(&data, "b");
|
||||
|
||||
// step2
|
||||
barrier.wait();
|
||||
barrier.wait();
|
||||
// Verify it still points to the old target.
|
||||
let data = fs::read_to_string(&pinned_path).unwrap();
|
||||
assert_eq!(&data, "b");
|
||||
|
||||
thread.join().unwrap();
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_new_pinned_path_buf() {
|
||||
let rootfs_dir = tempfile::tempdir().expect("failed to create tmpdir");
|
||||
let rootfs_path = rootfs_dir.path();
|
||||
let path = PinnedPathBuf::from_path(rootfs_path).unwrap();
|
||||
let _ = OpenOptions::new().read(true).open(&path).unwrap();
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_pinned_path_try_clone() {
|
||||
let rootfs_dir = tempfile::tempdir().expect("failed to create tmpdir");
|
||||
let rootfs_path = rootfs_dir.path();
|
||||
let path = PinnedPathBuf::from_path(rootfs_path).unwrap();
|
||||
let path2 = path.try_clone().unwrap();
|
||||
assert_ne!(path.as_path(), path2.as_path());
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_new_pinned_path_buf_from_nonexist_file() {
|
||||
let rootfs_dir = tempfile::tempdir().expect("failed to create tmpdir");
|
||||
let rootfs_path = rootfs_dir.path();
|
||||
PinnedPathBuf::new(rootfs_path, "does_not_exist").unwrap_err();
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_new_pinned_path_buf_without_read_perm() {
|
||||
let rootfs_dir = tempfile::tempdir().expect("failed to create tmpdir");
|
||||
let rootfs_path = rootfs_dir.path();
|
||||
let path = rootfs_path.join("write_only_file");
|
||||
|
||||
let mut file = OpenOptions::new()
|
||||
.read(false)
|
||||
.write(true)
|
||||
.create(true)
|
||||
.mode(0o200)
|
||||
.open(&path)
|
||||
.unwrap();
|
||||
file.write_all(&[0xa5u8]).unwrap();
|
||||
let md = fs::metadata(&path).unwrap();
|
||||
let umask = unsafe { libc::umask(0022) };
|
||||
unsafe { libc::umask(umask) };
|
||||
assert_eq!(md.mode() & 0o700, 0o200 & !umask);
|
||||
PinnedPathBuf::from_path(&path).unwrap();
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_pinned_path_buf_path_fd() {
|
||||
let rootfs_dir = tempfile::tempdir().expect("failed to create tmpdir");
|
||||
let rootfs_path = rootfs_dir.path();
|
||||
let path = rootfs_path.join("write_only_file");
|
||||
|
||||
let mut file = OpenOptions::new()
|
||||
.read(false)
|
||||
.write(true)
|
||||
.create(true)
|
||||
.mode(0o200)
|
||||
.open(&path)
|
||||
.unwrap();
|
||||
file.write_all(&[0xa5u8]).unwrap();
|
||||
let handle = PinnedPathBuf::from_path(&path).unwrap();
|
||||
// Check that `fstat()` etc works with the fd returned by `path_fd()`.
|
||||
let fd = handle.path_fd();
|
||||
let mut stat: libc::stat = unsafe { std::mem::zeroed() };
|
||||
let res = unsafe { libc::fstat(fd, &mut stat as *mut _) };
|
||||
assert_eq!(res, 0);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_pinned_path_buf_open_child() {
|
||||
let rootfs_dir = tempfile::tempdir().expect("failed to create tmpdir");
|
||||
let rootfs_path = rootfs_dir.path();
|
||||
let path = PinnedPathBuf::from_path(rootfs_path).unwrap();
|
||||
|
||||
fs::write(path.join("child"), "test").unwrap();
|
||||
let path = path.open_child(OsStr::new("child")).unwrap();
|
||||
let content = fs::read_to_string(&path).unwrap();
|
||||
assert_eq!(&content, "test");
|
||||
}
|
||||
}
|
||||
261
src/libs/safe-path/src/scoped_dir_builder.rs
Normal file
261
src/libs/safe-path/src/scoped_dir_builder.rs
Normal file
@ -0,0 +1,261 @@
|
||||
// Copyright (c) 2022 Alibaba Cloud
|
||||
//
|
||||
// SPDX-License-Identifier: Apache-2.0
|
||||
//
|
||||
|
||||
use std::io::{Error, ErrorKind, Result};
|
||||
use std::path::Path;
|
||||
|
||||
use crate::{scoped_join, scoped_resolve, PinnedPathBuf};
|
||||
|
||||
const DIRECTORY_MODE_DEFAULT: u32 = 0o777;
|
||||
const DIRECTORY_MODE_MASK: u32 = 0o777;
|
||||
|
||||
/// Safe version of `DirBuilder` to protect from TOCTOU style of attacks.
|
||||
///
|
||||
/// The `ScopedDirBuilder` is a counterpart for `DirBuilder`, with safety enhancements of:
|
||||
/// - ensuring the new directories are created under a specified `root` directory.
|
||||
/// - ensuring all created directories are still scoped under `root` even under symlink based
|
||||
/// attacks.
|
||||
/// - returning a [PinnedPathBuf] for the last level of directory, so it could be used for other
|
||||
/// operations safely.
|
||||
#[derive(Debug)]
|
||||
pub struct ScopedDirBuilder {
|
||||
root: PinnedPathBuf,
|
||||
mode: u32,
|
||||
recursive: bool,
|
||||
}
|
||||
|
||||
impl ScopedDirBuilder {
|
||||
/// Create a new instance of `ScopedDirBuilder` with with default mode/security settings.
|
||||
pub fn new<P: AsRef<Path>>(root: P) -> Result<Self> {
|
||||
let root = root.as_ref().canonicalize()?;
|
||||
let root = PinnedPathBuf::from_path(root)?;
|
||||
if !root.metadata()?.is_dir() {
|
||||
return Err(Error::new(
|
||||
ErrorKind::Other,
|
||||
format!("Invalid root path: {}", root.display()),
|
||||
));
|
||||
}
|
||||
|
||||
Ok(ScopedDirBuilder {
|
||||
root,
|
||||
mode: DIRECTORY_MODE_DEFAULT,
|
||||
recursive: false,
|
||||
})
|
||||
}
|
||||
|
||||
/// Indicates that directories should be created recursively, creating all parent directories.
|
||||
///
|
||||
/// Parents that do not exist are created with the same security and permissions settings.
|
||||
pub fn recursive(&mut self, recursive: bool) -> &mut Self {
|
||||
self.recursive = recursive;
|
||||
self
|
||||
}
|
||||
|
||||
/// Sets the mode to create new directories with. This option defaults to 0o755.
|
||||
pub fn mode(&mut self, mode: u32) -> &mut Self {
|
||||
self.mode = mode & DIRECTORY_MODE_MASK;
|
||||
self
|
||||
}
|
||||
|
||||
/// Creates the specified directory with the options configured in this builder.
|
||||
///
|
||||
/// This is a helper to create subdirectory with an absolute path, without stripping off
|
||||
/// `self.root`. So error will be returned if path does start with `self.root`.
|
||||
/// It is considered an error if the directory already exists unless recursive mode is enabled.
|
||||
pub fn create_with_unscoped_path<P: AsRef<Path>>(&self, path: P) -> Result<PinnedPathBuf> {
|
||||
if !path.as_ref().is_absolute() {
|
||||
return Err(Error::new(
|
||||
ErrorKind::Other,
|
||||
format!(
|
||||
"Expected absolute directory path: {}",
|
||||
path.as_ref().display()
|
||||
),
|
||||
));
|
||||
}
|
||||
// Partially canonicalize `path` so we can strip the `root` part.
|
||||
let scoped_path = scoped_join("/", path)?;
|
||||
let stripped_path = scoped_path.strip_prefix(self.root.target()).map_err(|_| {
|
||||
Error::new(
|
||||
ErrorKind::Other,
|
||||
format!(
|
||||
"Path {} is not under {}",
|
||||
scoped_path.display(),
|
||||
self.root.target().display()
|
||||
),
|
||||
)
|
||||
})?;
|
||||
|
||||
self.do_mkdir(&stripped_path)
|
||||
}
|
||||
|
||||
/// Creates sub-directory with the options configured in this builder.
|
||||
///
|
||||
/// It is considered an error if the directory already exists unless recursive mode is enabled.
|
||||
pub fn create<P: AsRef<Path>>(&self, path: P) -> Result<PinnedPathBuf> {
|
||||
let path = scoped_resolve(&self.root, path)?;
|
||||
self.do_mkdir(&path)
|
||||
}
|
||||
|
||||
fn do_mkdir(&self, path: &Path) -> Result<PinnedPathBuf> {
|
||||
assert!(path.is_relative());
|
||||
if path.file_name().is_none() {
|
||||
if !self.recursive {
|
||||
return Err(Error::new(
|
||||
ErrorKind::AlreadyExists,
|
||||
"directory already exists",
|
||||
));
|
||||
} else {
|
||||
return self.root.try_clone();
|
||||
}
|
||||
}
|
||||
|
||||
// Safe because `path` have at least one level.
|
||||
let levels = path.iter().count() - 1;
|
||||
let mut dir = self.root.try_clone()?;
|
||||
for (idx, comp) in path.iter().enumerate() {
|
||||
match dir.open_child(comp) {
|
||||
Ok(v) => {
|
||||
if !v.metadata()?.is_dir() {
|
||||
return Err(Error::new(
|
||||
ErrorKind::Other,
|
||||
format!("Path {} is not a directory", v.display()),
|
||||
));
|
||||
} else if !self.recursive && idx == levels {
|
||||
return Err(Error::new(
|
||||
ErrorKind::AlreadyExists,
|
||||
"directory already exists",
|
||||
));
|
||||
}
|
||||
dir = v;
|
||||
}
|
||||
Err(_e) => {
|
||||
if !self.recursive && idx != levels {
|
||||
return Err(Error::new(
|
||||
ErrorKind::NotFound,
|
||||
format!("parent directory does not exist"),
|
||||
));
|
||||
}
|
||||
dir = dir.mkdir(comp, self.mode)?;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Ok(dir)
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
use std::fs;
|
||||
use std::fs::DirBuilder;
|
||||
use std::os::unix::fs::{symlink, MetadataExt};
|
||||
use tempfile::tempdir;
|
||||
|
||||
#[test]
|
||||
fn test_scoped_dir_builder() {
|
||||
// create temporary directory to emulate container rootfs with symlink
|
||||
let rootfs_dir = tempdir().expect("failed to create tmpdir");
|
||||
DirBuilder::new()
|
||||
.create(rootfs_dir.path().join("b"))
|
||||
.unwrap();
|
||||
symlink(rootfs_dir.path().join("b"), rootfs_dir.path().join("a")).unwrap();
|
||||
let rootfs_path = &rootfs_dir.path().join("a");
|
||||
|
||||
// root directory doesn't exist
|
||||
ScopedDirBuilder::new(rootfs_path.join("__does_not_exist__")).unwrap_err();
|
||||
ScopedDirBuilder::new("__does_not_exist__").unwrap_err();
|
||||
|
||||
// root is a file
|
||||
fs::write(rootfs_path.join("txt"), "test").unwrap();
|
||||
ScopedDirBuilder::new(rootfs_path.join("txt")).unwrap_err();
|
||||
|
||||
let mut builder = ScopedDirBuilder::new(&rootfs_path).unwrap();
|
||||
|
||||
// file with the same name already exists.
|
||||
builder
|
||||
.create_with_unscoped_path(rootfs_path.join("txt"))
|
||||
.unwrap_err();
|
||||
// parent is a file
|
||||
builder.create("/txt/a").unwrap_err();
|
||||
// Not starting with root
|
||||
builder.create_with_unscoped_path("/txt/a").unwrap_err();
|
||||
// creating "." without recursive mode should fail
|
||||
builder
|
||||
.create_with_unscoped_path(rootfs_path.join("."))
|
||||
.unwrap_err();
|
||||
// parent doesn't exist
|
||||
builder
|
||||
.create_with_unscoped_path(rootfs_path.join("a/b"))
|
||||
.unwrap_err();
|
||||
builder.create("a/b/c").unwrap_err();
|
||||
|
||||
let path = builder.create("a").unwrap();
|
||||
assert!(rootfs_path.join("a").is_dir());
|
||||
assert_eq!(path.target(), rootfs_path.join("a").canonicalize().unwrap());
|
||||
|
||||
// Creating an existing directory without recursive mode should fail.
|
||||
builder
|
||||
.create_with_unscoped_path(rootfs_path.join("a"))
|
||||
.unwrap_err();
|
||||
|
||||
// Creating an existing directory with recursive mode should succeed.
|
||||
builder.recursive(true);
|
||||
let path = builder
|
||||
.create_with_unscoped_path(rootfs_path.join("a"))
|
||||
.unwrap();
|
||||
assert_eq!(path.target(), rootfs_path.join("a").canonicalize().unwrap());
|
||||
let path = builder.create(".").unwrap();
|
||||
assert_eq!(path.target(), rootfs_path.canonicalize().unwrap());
|
||||
|
||||
let umask = unsafe { libc::umask(0022) };
|
||||
unsafe { libc::umask(umask) };
|
||||
|
||||
builder.mode(0o740);
|
||||
let path = builder.create("a/b/c/d").unwrap();
|
||||
assert_eq!(
|
||||
path.target(),
|
||||
rootfs_path.join("a/b/c/d").canonicalize().unwrap()
|
||||
);
|
||||
assert!(rootfs_path.join("a/b/c/d").is_dir());
|
||||
assert_eq!(
|
||||
rootfs_path.join("a").metadata().unwrap().mode() & 0o777,
|
||||
DIRECTORY_MODE_DEFAULT & !umask,
|
||||
);
|
||||
assert_eq!(
|
||||
rootfs_path.join("a/b").metadata().unwrap().mode() & 0o777,
|
||||
0o740 & !umask
|
||||
);
|
||||
assert_eq!(
|
||||
rootfs_path.join("a/b/c").metadata().unwrap().mode() & 0o777,
|
||||
0o740 & !umask
|
||||
);
|
||||
assert_eq!(
|
||||
rootfs_path.join("a/b/c/d").metadata().unwrap().mode() & 0o777,
|
||||
0o740 & !umask
|
||||
);
|
||||
|
||||
// Creating should fail if some components are not directory.
|
||||
builder.create("txt/e/f").unwrap_err();
|
||||
fs::write(rootfs_path.join("a/b/txt"), "test").unwrap();
|
||||
builder.create("a/b/txt/h/i").unwrap_err();
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_create_root() {
|
||||
let mut builder = ScopedDirBuilder::new("/").unwrap();
|
||||
builder.recursive(true);
|
||||
builder.create("/").unwrap();
|
||||
builder.create(".").unwrap();
|
||||
builder.create("..").unwrap();
|
||||
builder.create("../../.").unwrap();
|
||||
builder.create("").unwrap();
|
||||
builder.create_with_unscoped_path("/").unwrap();
|
||||
builder.create_with_unscoped_path(".").unwrap();
|
||||
builder.create_with_unscoped_path("..").unwrap();
|
||||
builder.create_with_unscoped_path("../../.").unwrap();
|
||||
builder.create_with_unscoped_path("").unwrap();
|
||||
}
|
||||
}
|
||||
324
src/libs/safe-path/src/scoped_path_resolver.rs
Normal file
324
src/libs/safe-path/src/scoped_path_resolver.rs
Normal file
@ -0,0 +1,324 @@
|
||||
// Copyright (c) 2022 Alibaba Cloud
|
||||
//
|
||||
// SPDX-License-Identifier: Apache-2.0
|
||||
//
|
||||
|
||||
use std::io::{Error, ErrorKind, Result};
|
||||
use std::path::{Component, Path, PathBuf};
|
||||
|
||||
// Follow the same configuration as
|
||||
// [secure_join](https://github.com/cyphar/filepath-securejoin/blob/master/join.go#L51)
|
||||
const MAX_SYMLINK_DEPTH: u32 = 255;
|
||||
|
||||
fn do_scoped_resolve<R: AsRef<Path>, U: AsRef<Path>>(
|
||||
root: R,
|
||||
unsafe_path: U,
|
||||
) -> Result<(PathBuf, PathBuf)> {
|
||||
let root = root.as_ref().canonicalize()?;
|
||||
|
||||
let mut nlinks = 0u32;
|
||||
let mut curr_path = unsafe_path.as_ref().to_path_buf();
|
||||
'restart: loop {
|
||||
let mut subpath = PathBuf::new();
|
||||
let mut iter = curr_path.components();
|
||||
|
||||
'next_comp: while let Some(comp) = iter.next() {
|
||||
match comp {
|
||||
// Linux paths don't have prefixes.
|
||||
Component::Prefix(_) => {
|
||||
return Err(Error::new(
|
||||
ErrorKind::Other,
|
||||
format!("Invalid path prefix in: {}", unsafe_path.as_ref().display()),
|
||||
));
|
||||
}
|
||||
// `RootDir` should always be the first component, and Path::components() ensures
|
||||
// that.
|
||||
Component::RootDir | Component::CurDir => {
|
||||
continue 'next_comp;
|
||||
}
|
||||
Component::ParentDir => {
|
||||
subpath.pop();
|
||||
}
|
||||
Component::Normal(n) => {
|
||||
let path = root.join(&subpath).join(n);
|
||||
if let Ok(v) = path.read_link() {
|
||||
nlinks += 1;
|
||||
if nlinks > MAX_SYMLINK_DEPTH {
|
||||
return Err(Error::new(
|
||||
ErrorKind::Other,
|
||||
format!(
|
||||
"Too many levels of symlinks: {}",
|
||||
unsafe_path.as_ref().display()
|
||||
),
|
||||
));
|
||||
}
|
||||
curr_path = if v.is_absolute() {
|
||||
v.join(iter.as_path())
|
||||
} else {
|
||||
subpath.join(v).join(iter.as_path())
|
||||
};
|
||||
continue 'restart;
|
||||
} else {
|
||||
subpath.push(n);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return Ok((root, subpath));
|
||||
}
|
||||
}
|
||||
|
||||
/// Resolve `unsafe_path` to a relative path, rooted at and constrained by `root`.
|
||||
///
|
||||
/// The `scoped_resolve()` function assumes `root` exists and is an absolute path. It processes
|
||||
/// each path component in `unsafe_path` as below:
|
||||
/// - assume it's not a symlink and output if the component doesn't exist yet.
|
||||
/// - ignore if it's "/" or ".".
|
||||
/// - go to parent directory but constrained by `root` if it's "..".
|
||||
/// - recursively resolve to the real path if it's a symlink. All symlink resolutions will be
|
||||
/// constrained by `root`.
|
||||
/// - otherwise output the path component.
|
||||
///
|
||||
/// # Arguments
|
||||
/// - `root`: the absolute path to constrain the symlink resolution.
|
||||
/// - `unsafe_path`: the path to resolve.
|
||||
///
|
||||
/// Note that the guarantees provided by this function only apply if the path components in the
|
||||
/// returned PathBuf are not modified (in other words are not replaced with symlinks on the
|
||||
/// filesystem) after this function has returned. You may use [crate::PinnedPathBuf] to protect
|
||||
/// from such TOCTOU attacks.
|
||||
pub fn scoped_resolve<R: AsRef<Path>, U: AsRef<Path>>(root: R, unsafe_path: U) -> Result<PathBuf> {
|
||||
do_scoped_resolve(root, unsafe_path).map(|(_root, path)| path)
|
||||
}
|
||||
|
||||
/// Safely join `unsafe_path` to `root`, and ensure `unsafe_path` is scoped under `root`.
|
||||
///
|
||||
/// The `scoped_join()` function assumes `root` exists and is an absolute path. It safely joins the
|
||||
/// two given paths and ensures:
|
||||
/// - The returned path is guaranteed to be scoped inside `root`.
|
||||
/// - Any symbolic links in the path are evaluated with the given `root` treated as the root of the
|
||||
/// filesystem, similar to a chroot.
|
||||
///
|
||||
/// It's modelled after [secure_join](https://github.com/cyphar/filepath-securejoin), but only
|
||||
/// for Linux systems.
|
||||
///
|
||||
/// # Arguments
|
||||
/// - `root`: the absolute path to scope the symlink evaluation.
|
||||
/// - `unsafe_path`: the path to evaluated and joint with `root`. It is unsafe since it may try to
|
||||
/// escape from the `root` by using "../" or symlinks.
|
||||
///
|
||||
/// # Security
|
||||
/// On success return, the `scoped_join()` function guarantees that:
|
||||
/// - The resulting PathBuf must be a child path of `root` and will not contain any symlink path
|
||||
/// components (they will all get expanded).
|
||||
/// - When expanding symlinks, all symlink path components must be resolved relative to the provided
|
||||
/// `root`. In particular, this can be considered a userspace implementation of how chroot(2)
|
||||
/// operates on file paths.
|
||||
/// - Non-existent path components are unaffected.
|
||||
///
|
||||
/// Note that the guarantees provided by this function only apply if the path components in the
|
||||
/// returned string are not modified (in other words are not replaced with symlinks on the
|
||||
/// filesystem) after this function has returned. You may use [crate::PinnedPathBuf] to protect
|
||||
/// from such TOCTTOU attacks.
|
||||
pub fn scoped_join<R: AsRef<Path>, U: AsRef<Path>>(root: R, unsafe_path: U) -> Result<PathBuf> {
|
||||
do_scoped_resolve(root, unsafe_path).map(|(root, path)| root.join(path))
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
use std::fs::DirBuilder;
|
||||
use std::os::unix::fs;
|
||||
use tempfile::tempdir;
|
||||
|
||||
#[allow(dead_code)]
|
||||
#[derive(Debug)]
|
||||
struct TestData<'a> {
|
||||
name: &'a str,
|
||||
rootfs: &'a Path,
|
||||
unsafe_path: &'a str,
|
||||
result: &'a str,
|
||||
}
|
||||
|
||||
fn exec_tests(tests: &[TestData]) {
|
||||
for (i, t) in tests.iter().enumerate() {
|
||||
// Create a string containing details of the test
|
||||
let msg = format!("test[{}]: {:?}", i, t);
|
||||
let result = scoped_resolve(t.rootfs, t.unsafe_path).unwrap();
|
||||
let msg = format!("{}, result: {:?}", msg, result);
|
||||
|
||||
// Perform the checks
|
||||
assert_eq!(&result, Path::new(t.result), "{}", msg);
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_scoped_resolve() {
|
||||
// create temporary directory to emulate container rootfs with symlink
|
||||
let rootfs_dir = tempdir().expect("failed to create tmpdir");
|
||||
DirBuilder::new()
|
||||
.create(rootfs_dir.path().join("b"))
|
||||
.unwrap();
|
||||
fs::symlink(rootfs_dir.path().join("b"), rootfs_dir.path().join("a")).unwrap();
|
||||
let rootfs_path = &rootfs_dir.path().join("a");
|
||||
|
||||
let tests = [
|
||||
TestData {
|
||||
name: "normal path",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "a/b/c",
|
||||
result: "a/b/c",
|
||||
},
|
||||
TestData {
|
||||
name: "path with .. at beginning",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "../../../a/b/c",
|
||||
result: "a/b/c",
|
||||
},
|
||||
TestData {
|
||||
name: "path with complex .. pattern",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "../../../a/../../b/../../c",
|
||||
result: "c",
|
||||
},
|
||||
TestData {
|
||||
name: "path with .. in middle",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "/usr/bin/../../bin/ls",
|
||||
result: "bin/ls",
|
||||
},
|
||||
TestData {
|
||||
name: "path with . and ..",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "/usr/./bin/../../bin/./ls",
|
||||
result: "bin/ls",
|
||||
},
|
||||
TestData {
|
||||
name: "path with . at end",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "/usr/./bin/../../bin/./ls/.",
|
||||
result: "bin/ls",
|
||||
},
|
||||
TestData {
|
||||
name: "path try to escape by ..",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "/usr/./bin/../../../../bin/./ls/../ls",
|
||||
result: "bin/ls",
|
||||
},
|
||||
TestData {
|
||||
name: "path with .. at the end",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "/usr/./bin/../../bin/./ls/..",
|
||||
result: "bin",
|
||||
},
|
||||
TestData {
|
||||
name: "path ..",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "..",
|
||||
result: "",
|
||||
},
|
||||
TestData {
|
||||
name: "path .",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: ".",
|
||||
result: "",
|
||||
},
|
||||
TestData {
|
||||
name: "path /",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "/",
|
||||
result: "",
|
||||
},
|
||||
TestData {
|
||||
name: "empty path",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "",
|
||||
result: "",
|
||||
},
|
||||
];
|
||||
|
||||
exec_tests(&tests);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_scoped_resolve_invalid() {
|
||||
scoped_resolve("./root_is_not_absolute_path", ".").unwrap_err();
|
||||
scoped_resolve("C:", ".").unwrap_err();
|
||||
scoped_resolve(r#"\\server\test"#, ".").unwrap_err();
|
||||
scoped_resolve(r#"http://localhost/test"#, ".").unwrap_err();
|
||||
// Chinese Unicode characters
|
||||
scoped_resolve(r#"您好"#, ".").unwrap_err();
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_scoped_resolve_symlink() {
|
||||
// create temporary directory to emulate container rootfs with symlink
|
||||
let rootfs_dir = tempdir().expect("failed to create tmpdir");
|
||||
let rootfs_path = &rootfs_dir.path();
|
||||
std::fs::create_dir(rootfs_path.join("symlink_dir")).unwrap();
|
||||
|
||||
fs::symlink("../../../", rootfs_path.join("1")).unwrap();
|
||||
let tests = [TestData {
|
||||
name: "relative symlink beyond root",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "1",
|
||||
result: "",
|
||||
}];
|
||||
exec_tests(&tests);
|
||||
|
||||
fs::symlink("/dddd", rootfs_path.join("2")).unwrap();
|
||||
let tests = [TestData {
|
||||
name: "abs symlink pointing to non-exist directory",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "2",
|
||||
result: "dddd",
|
||||
}];
|
||||
exec_tests(&tests);
|
||||
|
||||
fs::symlink("/", rootfs_path.join("3")).unwrap();
|
||||
let tests = [TestData {
|
||||
name: "abs symlink pointing to /",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "3",
|
||||
result: "",
|
||||
}];
|
||||
exec_tests(&tests);
|
||||
|
||||
fs::symlink("usr/bin/../bin/ls", rootfs_path.join("4")).unwrap();
|
||||
let tests = [TestData {
|
||||
name: "symlink with one ..",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "4",
|
||||
result: "usr/bin/ls",
|
||||
}];
|
||||
exec_tests(&tests);
|
||||
|
||||
fs::symlink("usr/bin/../../bin/ls", rootfs_path.join("5")).unwrap();
|
||||
let tests = [TestData {
|
||||
name: "symlink with two ..",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "5",
|
||||
result: "bin/ls",
|
||||
}];
|
||||
exec_tests(&tests);
|
||||
|
||||
fs::symlink(
|
||||
"../usr/bin/../../../bin/ls",
|
||||
rootfs_path.join("symlink_dir/6"),
|
||||
)
|
||||
.unwrap();
|
||||
let tests = [TestData {
|
||||
name: "symlink try to escape",
|
||||
rootfs: rootfs_path,
|
||||
unsafe_path: "symlink_dir/6",
|
||||
result: "bin/ls",
|
||||
}];
|
||||
exec_tests(&tests);
|
||||
|
||||
// Detect symlink loop.
|
||||
fs::symlink("/endpoint_b", rootfs_path.join("endpoint_a")).unwrap();
|
||||
fs::symlink("/endpoint_a", rootfs_path.join("endpoint_b")).unwrap();
|
||||
scoped_join(rootfs_path, "endpoint_a").unwrap_err();
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user