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specs-go/config: add Landlock LSM support
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Linux kernel 5.13 adds support for Landlock Linux Security Module (LSM).
This allows unprivileged processes to create safe security sandboxes
that can securely restrict the ambient rights (e.g. global filesystem
access) for themselves.

opencontainers#1110

Signed-off-by: Kailun Qin <[email protected]>
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kailun-qin committed Sep 2, 2022
1 parent 86290f6 commit 3b00e43
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Showing 4 changed files with 207 additions and 2 deletions.
80 changes: 78 additions & 2 deletions config.md
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Expand Up @@ -216,7 +216,27 @@ For Linux-based systems, the `process` object supports the following process-spe
This is a per-process setting, where as [`disableOOMKiller`](config-linux.md#memory) is scoped for a memory cgroup.
For more information on how these two settings work together, see [the memory cgroup documentation section 10. OOM Contol][cgroup-v1-memory_2].
* **`selinuxLabel`** (string, OPTIONAL) specifies the SELinux label for the process.
For more information about SELinux, see [SELinux documentation][selinux].
For more information about SELinux, see [SELinux documentation][selinux].
* **`landlock`** (object, OPTIONAL) specifies the Landlock unprivileged access control settings for the container process.
Note that `noNewPrivileges` must be set to true to use this feature.
For more information about Landlock, see [Landlock documentation][landlock].
`landlock` contains the following properties:

* **`ruleset`** (object, OPTIONAL) the `ruleset` field identifies a set of rules (i.e., actions on objects) that need to be handled (i.e., restricted).
The `ruleset` currently contains the following types:
* **`handledAccessFS`** (array of strings, OPTIONAL) is an array of FS typed actions that are handled by a ruleset.
If no rule explicitly allow them, they should then be forbidden.
* **`rules`** (object, OPTIONAL) the `rules` field specifies the security policies (i.e., actions allowed on objects) to be added to an existing ruleset.
The `rules` currently contains the following types:
* **`pathBeneath`** (array of objects, OPTIONAL) is an array of the file-hierarchy typed rules.
Entries in the array contain the following properties:
* **`allowedAccess`** (array of strings, OPTIONAL) is an array of FS typed actions that are allowed by a rule.
* **`paths`** (array of strings, OPTIONAL) is an array of files or parent directories of the file hierarchies to restrict.
* **`disableBestEffort`** (bool, OPTIONAL) the `disableBestEffort` field disables the best-effort security approach for Landlock access rights.
This is for conditions when the Landlock access rights explicitly configured by the container are not supported or available in the running kernel.
If the best-effort security approach is enabled (`false`), the runtime SHOULD enforce the strongest rules configured up to the current kernel support, and only be [logged as a warning](runtime.md#warnings) for those not supported.
If disabled (`true`), the runtime MUST [generate an error](runtime.md#errors) if one or more rules specified by the container is not supported.
Default is `false`, i.e., following a best-effort security approach.

### <a name="configUser" />User

Expand Down Expand Up @@ -258,6 +278,61 @@ _Note: symbolic name for uid and gid, such as uname and gname respectively, are
],
"apparmorProfile": "acme_secure_profile",
"selinuxLabel": "system_u:system_r:svirt_lxc_net_t:s0:c124,c675",
"landlock": {
"ruleset": {
"handledAccessFS": [
"execute",
"write_file",
"read_file",
"read_dir",
"remove_dir",
"remove_file",
"make_char",
"make_dir",
"make_reg",
"make_sock",
"make_fifo",
"make_block",
"make_sym"
]
},
"rules": {
"pathBeneath": [
{
"allowedAccess": [
"execute",
"read_file",
"read_dir"
],
"paths": [
"/usr",
"/bin"
]
},
{
"allowedAccess": [
"execute",
"write_file",
"read_file",
"read_dir",
"remove_dir",
"remove_file",
"make_char",
"make_dir",
"make_reg",
"make_sock",
"make_fifo",
"make_block",
"make_sym"
],
"paths": [
"/tmp"
]
}
]
},
"disableBestEffort": false
},
"noNewPrivileges": true,
"capabilities": {
"bounding": [
Expand Down Expand Up @@ -978,7 +1053,8 @@ Here is a full example `config.json` for reference.

[apparmor]: https://wiki.ubuntu.com/AppArmor
[cgroup-v1-memory_2]: https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt
[selinux]:http://selinuxproject.org/page/Main_Page
[selinux]: http://selinuxproject.org/page/Main_Page
[landlock]: https://landlock.io
[no-new-privs]: https://www.kernel.org/doc/Documentation/prctl/no_new_privs.txt
[proc_2]: https://www.kernel.org/doc/Documentation/filesystems/proc.txt
[umask.2]: http://pubs.opengroup.org/onlinepubs/009695399/functions/umask.html
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14 changes: 14 additions & 0 deletions schema/config-schema.json
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Expand Up @@ -144,6 +144,20 @@
"selinuxLabel": {
"type": "string"
},
"landlock": {
"type": "object",
"properties": {
"ruleset": {
"$ref": "defs.json#/definitions/LandlockRuleset"
},
"rules": {
"$ref": "defs.json#/definitions/LandlockRules"
},
"disableBestEffort": {
"type": "boolean"
}
}
},
"noNewPrivileges": {
"type": "boolean"
},
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57 changes: 57 additions & 0 deletions schema/defs.json
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Expand Up @@ -165,6 +165,63 @@
},
"annotations": {
"$ref": "#/definitions/mapStringString"
},
"LandlockFSAction": {
"type": "string",
"enum": [
"execute",
"write_file",
"read_file",
"read_dir",
"remove_dir",
"remove_file",
"make_char",
"make_dir",
"make_reg",
"make_sock",
"make_fifo",
"make_block",
"make_sym"
]
},
"ArrayOfLandlockFSActions": {
"type": "array",
"items": {
"$ref": "#/definitions/LandlockFSAction"
}
},
"LandlockRuleset": {
"type": "object",
"properties": {
"handledAccessFS": {
"$ref": "#/definitions/ArrayOfLandlockFSActions"
}
}
},
"LandlockRulePathBeneath": {
"type": "object",
"properties": {
"allowedAccess": {
"$ref": "#/definitions/ArrayOfLandlockFSActions"
},
"paths": {
"$ref": "#/definitions/ArrayOfStrings"
}
}
},
"ArrayOfLandlockRulePathBeneaths": {
"type": "array",
"items": {
"$ref": "#/definitions/LandlockRulePathBeneath"
}
},
"LandlockRules": {
"type": "object",
"properties": {
"pathBeneath": {
"$ref": "#/definitions/ArrayOfLandlockRulePathBeneaths"
}
}
}
}
}
58 changes: 58 additions & 0 deletions specs-go/config.go
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Expand Up @@ -62,8 +62,66 @@ type Process struct {
OOMScoreAdj *int `json:"oomScoreAdj,omitempty" platform:"linux"`
// SelinuxLabel specifies the selinux context that the container process is run as.
SelinuxLabel string `json:"selinuxLabel,omitempty" platform:"linux"`
// Landlock specifies the Landlock unprivileged access control settings for the container process.
// `noNewPrivileges` must be enabled to use Landlock.
Landlock *Landlock `json:"landlock,omitempty" platform:"linux"`
}

// Landlock specifies the Landlock unprivileged access control settings for the container process.
type Landlock struct {
// Ruleset identifies a set of rules (i.e., actions on objects) that need to be handled.
Ruleset *LandlockRuleset `json:"ruleset,omitempty" platform:"linux"`
// Rules are the security policies (i.e., actions allowed on objects) to be added to an existing ruleset.
Rules *LandlockRules `json:"rules,omitempty" platform:"linux"`
// DisableBestEffort disables the best-effort security approach for Landlock access rights.
// This is for conditions when the Landlock access rights explicitly configured by the container are not
// supported or available in the running kernel.
// Default is false, i.e., following a best-effort security approach.
DisableBestEffort bool `json:"disableBestEffort,omitempty" platform:"linux"`
}

// LandlockRuleset identifies a set of rules (i.e., actions on objects) that need to be handled.
type LandlockRuleset struct {
// HandledAccessFS is a list of actions that is handled by this ruleset and should then be
// forbidden if no rule explicitly allow them.
HandledAccessFS []LandlockFSAction `json:"handledAccessFS,omitempty" platform:"linux"`
}

// LandlockRules represents the security policies (i.e., actions allowed on objects).
type LandlockRules struct {
// PathBeneath specifies the file-hierarchy typed rules.
PathBeneath []LandlockRulePathBeneath `json:"pathBeneath,omitempty" platform:"linux"`
}

// LandlockRulePathBeneath defines the file-hierarchy typed rule that grants the access rights specified by
// `AllowedAccess` to the file hierarchies under the given `Paths`.
type LandlockRulePathBeneath struct {
// AllowedAccess contains a list of allowed filesystem actions for the file hierarchies.
AllowedAccess []LandlockFSAction `json:"allowedAccess,omitempty" platform:"linux"`
// Paths are the files or parent directories of the file hierarchies to restrict.
Paths []string `json:"paths,omitempty" platform:"linux"`
}

// LandlockFSAction used to specify the FS actions that are handled by a ruleset or allowed by a rule.
type LandlockFSAction string

// Define actions on files and directories that Landlock can restrict a sandboxed process to.
const (
LLFSActExecute LandlockFSAction = "execute"
LLFSActWriteFile LandlockFSAction = "write_file"
LLFSActReadFile LandlockFSAction = "read_file"
LLFSActReadDir LandlockFSAction = "read_dir"
LLFSActRemoveDir LandlockFSAction = "remove_dir"
LLFSActRemoveFile LandlockFSAction = "remove_file"
LLFSActMakeChar LandlockFSAction = "make_char"
LLFSActMakeDir LandlockFSAction = "make_dir"
LLFSActMakeReg LandlockFSAction = "make_reg"
LLFSActMakeSock LandlockFSAction = "make_sock"
LLFSActMakeFifo LandlockFSAction = "make_fifo"
LLFSActMakeBlock LandlockFSAction = "make_block"
LLFSActMakeSym LandlockFSAction = "make_sym"
)

// LinuxCapabilities specifies the list of allowed capabilities that are kept for a process.
// http://man7.org/linux/man-pages/man7/capabilities.7.html
type LinuxCapabilities struct {
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