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add uid/gid mapping to mount #296

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Merged
utam0k merged 5 commits into from
Dec 29, 2025
Merged

add uid/gid mapping to mount #296

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ad0a564
add uid/gid mapping config
YamasouA Oct 11, 2025
82016e2
cargo fmt
YamasouA Oct 14, 2025
fa72ef6
fix review comment
YamasouA Dec 27, 2025
54138ad
fix format
YamasouA Dec 29, 2025
9e8d302
tweak
YamasouA Dec 29, 2025
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31 changes: 31 additions & 0 deletions src/runtime/miscellaneous.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
use crate::error::OciSpecError;
use crate::runtime::LinuxIdMapping;
use derive_builder::Builder;
use getset::{CopyGetters, Getters, MutGetters, Setters};
use serde::{Deserialize, Serialize};
Expand Down Expand Up @@ -76,6 +77,22 @@ pub struct Mount {
#[serde(default, skip_serializing_if = "Option::is_none")]
/// Options are fstab style mount options.
options: Option<Vec<String>>,

#[serde(
default,
skip_serializing_if = "Option::is_none",
rename = "uidMappings"
)]
/// UID mappings used for changing file owners w/o calling chown, fs should support it. Every mount point could have its own mapping.
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@saschagrunert saschagrunert Nov 3, 2025

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How about being a bit more verbose here:

Suggested change
/// UID mappings used for changing file owners w/o calling chown, fs should support it. Every mount point could have its own mapping.
/// UID mappings for ID-mapped mounts (Linux 5.12+).
///
/// Specifies how to map UIDs from the source filesystem to the destination mount point.
/// This allows changing file ownership without calling chown.
///
/// **Important**: If specified, gid_mappings MUST also be specified.
/// The mount options SHOULD include "idmap" or "ridmap".
///
/// See: https://github.com/opencontainers/runtime-spec/blob/main/config.md#posix-platform-mounts

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@YamasouA YamasouA Dec 27, 2025

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@saschagrunert
Sorry for the late response.
I've fixed your review comments.

uid_mappings: Option<Vec<LinuxIdMapping>>,

#[serde(
default,
skip_serializing_if = "Option::is_none",
rename = "gidMappings"
)]
/// GID mappings used for changing file owners w/o calling chown, fs should support it. Every mount point could have its own mapping.
gid_mappings: Option<Vec<LinuxIdMapping>>,
Comment on lines 80 to 111
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@saschagrunert saschagrunert Nov 3, 2025

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According to the OCI spec, uidMappings and gidMappings must be specified together. The current implementation allows setting one without the other.

I'd say we could add validation in the builder or as a separate validation method, like:

  • Add a custom build() validation in derive_builder
  • Add a validation method on Mount to check consistency
  • Document this requirement in the field comments

}

/// utility function to generate default config for mounts.
Expand All @@ -86,6 +103,8 @@ pub fn get_default_mounts() -> Vec<Mount> {
typ: "proc".to_string().into(),
source: PathBuf::from("proc").into(),
options: None,
uid_mappings: None,
gid_mappings: None,
},
Mount {
destination: PathBuf::from("/dev"),
Expand All @@ -98,6 +117,8 @@ pub fn get_default_mounts() -> Vec<Mount> {
"size=65536k".into(),
]
.into(),
uid_mappings: None,
gid_mappings: None,
},
Mount {
destination: PathBuf::from("/dev/pts"),
Expand All @@ -112,6 +133,8 @@ pub fn get_default_mounts() -> Vec<Mount> {
"gid=5".into(),
]
.into(),
uid_mappings: None,
gid_mappings: None,
},
Mount {
destination: PathBuf::from("/dev/shm"),
Expand All @@ -125,12 +148,16 @@ pub fn get_default_mounts() -> Vec<Mount> {
"size=65536k".into(),
]
.into(),
uid_mappings: None,
gid_mappings: None,
},
Mount {
destination: PathBuf::from("/dev/mqueue"),
typ: "mqueue".to_string().into(),
source: PathBuf::from("mqueue").into(),
options: vec!["nosuid".into(), "noexec".into(), "nodev".into()].into(),
uid_mappings: None,
gid_mappings: None,
},
Mount {
destination: PathBuf::from("/sys"),
Expand All @@ -143,6 +170,8 @@ pub fn get_default_mounts() -> Vec<Mount> {
"ro".into(),
]
.into(),
uid_mappings: None,
gid_mappings: None,
},
Mount {
destination: PathBuf::from("/sys/fs/cgroup"),
Expand All @@ -156,6 +185,8 @@ pub fn get_default_mounts() -> Vec<Mount> {
"ro".into(),
]
.into(),
uid_mappings: None,
gid_mappings: None,
},
]
}
Expand Down
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