51a2212d3d
* client: sandbox go-getter subprocess with landlock This PR re-implements the getter package for artifact downloads as a subprocess. Key changes include On all platforms, run getter as a child process of the Nomad agent. On Linux platforms running as root, run the child process as the nobody user. On supporting Linux kernels, uses landlock for filesystem isolation (via go-landlock). On all platforms, restrict environment variables of the child process to a static set. notably TMP/TEMP now points within the allocation's task directory kernel.landlock attribute is fingerprinted (version number or unavailable) These changes make Nomad client more resilient against a faulty go-getter implementation that may panic, and more secure against bad actors attempting to use artifact downloads as a privilege escalation vector. Adds new e2e/artifact suite for ensuring artifact downloading works. TODO: Windows git test (need to modify the image, etc... followup PR) * landlock: fixup items from cr * cr: fixup tests and go.mod file
53 lines
1.1 KiB
Go
53 lines
1.1 KiB
Go
//go:build unix
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package users
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import (
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"fmt"
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"os/user"
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"strconv"
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)
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var (
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// nobody is a cached copy of the nobody user, which is going to be looked-up
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// frequently and is unlikely to be modified on the underlying system.
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nobody user.User
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// nobodyUID is a cached copy of the int value of the nobody user's UID.
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nobodyUID uint32
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// nobodyGID int is a cached copy of the int value of the nobody users's GID.
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nobodyGID uint32
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)
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// Nobody returns User data for the "nobody" user on the system, bypassing the
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// locking / file read / NSS lookup.
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func Nobody() user.User {
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return nobody
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}
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// NobodyIDs returns the integer UID and GID of the nobody user.
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func NobodyIDs() (uint32, uint32) {
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return nobodyUID, nobodyGID
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}
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func init() {
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u, err := Lookup("nobody")
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if err != nil {
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panic(fmt.Sprintf("failed to lookup nobody user: %v", err))
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}
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nobody = *u
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uid, err := strconv.Atoi(u.Uid)
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if err != nil {
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panic(fmt.Sprintf("failed to parse nobody UID: %v", err))
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}
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gid, err := strconv.Atoi(u.Gid)
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if err != nil {
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panic(fmt.Sprintf("failed to parse nobody GID: %v", err))
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}
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nobodyUID, nobodyGID = uint32(uid), uint32(gid)
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}
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