Trouble running exec.Command() as a different unix user.

[AJ Bahnken]

Hey Everyone,

I am having trouble with running exec.Command() as a different user. I have tried a few different users, so I do not think that is the problem. The error I am getting is "fork/exec /bin/date: operation not permitted". I tried googling around, but couldn't find any mention of this exact problem. I have tried a few different simple unix commands other than date as well. Also, not sure if it is relevant, but I am using Ubuntu 14.04 and go version go1.4 linux/amd64.

Any ideas?

Stackoverflow Answer I followed to get here: http://stackoverflow.com/questions/21705950/running-external-commands-through-os-exec-under-another-user

Code:

package main

import (
        "fmt"
        "os/exec"
        "os/user"
        "strconv"
        "syscall"
)

func main() {
        cmd := exec.Command("date")

        myuser, _ := user.Current()

        uid, _ := strconv.Atoi(myuser.Uid)
        gid, _ := strconv.Atoi(myuser.Gid)

        cmd.SysProcAttr = &syscall.SysProcAttr{}
        cmd.SysProcAttr.Credential = &syscall.Credential{Uid: uint32(uid), Gid: uint32(gid)}

        out, err := cmd.Output()
        if err != nil {
                fmt.Printf("Run Command got an Error: %s\n", err)
                return
        }
        fmt.Println(out)
}

Pastebin link: http://pastebin.com/WetNsnvH

Final Output:
Run Command got an Error: fork/exec /bin/date: operation not permitted


Thanks so much,
AJ

[James Bardin]

On Friday, March 27, 2015 at 12:51:56 PM UTC-4, AJ Bahnken wrote:

Final Output:
Run Command got an Error: fork/exec /bin/date: operation not permitted

Are you running this as root? (or  do have the the appropriate capabilities set?)

[AJ B]

So I just ran it as root and it worked. Thanks for the help. But why wouldn't my default user be able to run a command as itself using a binary it obviously has permissions to run?

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AJ Bahnken / @ajvbahnken

[James Bardin]

On Fri, Mar 27, 2015 at 3:38 PM, AJ B <a...@ajvb.me> wrote:

So I just ran it as root and it worked. Thanks for the help. But why wouldn't my default user be able to run a command as itself using a binary it obviously has permissions to run?

Because setuid and setgid are privileged calls, regardless of the values you pass to them. 

[worc...@googlemail.com]

Hi AJ!

Note, this issue was solved in go 1.9 with the introduction of NoSetGroups property of syscall.SysProcAttr.

See https://walac.github.io/golang-patch/ for context.

Pete