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Merge pull request moby#47567 from thaJeztah/move_rootless_mountopts
daemon: move getUnprivilegedMountFlags to internal package
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Original file line number | Diff line number | Diff line change |
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package mountopts | ||
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import ( | ||
"golang.org/x/sys/unix" | ||
) | ||
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// UnprivilegedMountFlags gets the set of mount flags that are set on the mount that contains the given | ||
// path and are locked by CL_UNPRIVILEGED. This is necessary to ensure that | ||
// bind-mounting "with options" will not fail with user namespaces, due to | ||
// kernel restrictions that require user namespace mounts to preserve | ||
// CL_UNPRIVILEGED locked flags. | ||
// | ||
// TODO: Move to github.com/moby/sys/mount, and update BuildKit copy of this code as well (https://github.com/moby/buildkit/blob/v0.13.0/util/rootless/mountopts/mountopts_linux.go#L11-L18) | ||
func UnprivilegedMountFlags(path string) ([]string, error) { | ||
var statfs unix.Statfs_t | ||
if err := unix.Statfs(path, &statfs); err != nil { | ||
return nil, err | ||
} | ||
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// The set of keys come from https://github.com/torvalds/linux/blob/v4.13/fs/namespace.c#L1034-L1048. | ||
unprivilegedFlags := map[uint64]string{ | ||
unix.MS_RDONLY: "ro", | ||
unix.MS_NODEV: "nodev", | ||
unix.MS_NOEXEC: "noexec", | ||
unix.MS_NOSUID: "nosuid", | ||
unix.MS_NOATIME: "noatime", | ||
unix.MS_RELATIME: "relatime", | ||
unix.MS_NODIRATIME: "nodiratime", | ||
} | ||
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var flags []string | ||
for mask, flag := range unprivilegedFlags { | ||
if uint64(statfs.Flags)&mask == mask { | ||
flags = append(flags, flag) | ||
} | ||
} | ||
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return flags, nil | ||
} |