How to handle gosec linter warning: Potential file inclusion via variable

Question

How do I solve the following warning from gosec linter:

::warning: Potential file inclusion via variable,MEDIUM,HIGH (gosec)

The linter is warning me on the first line of this function:

func File2lines(filePath string) ([]string, error) {
    f, err := os.Open(filePath) //Warning here
    if err != nil {
        return nil, err
    }
    defer f.Close()
    return linesFromReader(f)
}

I have tried reading up on local file inclusion, but cannot see how that would be applicable here.

Answer 1

Where does the path come from? If you're not absolutely sure it can never have user input, best to clean it before use and use a known prefix, eg:

filePath = filepath.Join(basePath,filepath.Clean(filePath))
f, err := os.Open(filePath)

That should fix the complaint. This is a reasonable precaution anyway even if you think it is safe now, in case later someone uses your function with user data.

Answer 2

No one said the linter was smart . Looking at the function in isolation, it's impossible to say if there's a security issue. If the function is called with a filePath that's user-supplied and insufficiently validated, and it runs in a context where it can read files that the user would not be able to otherwise (eg in a program with elevated privileges, or on a remote server), then there is a probably issue. Otherwise, the only thing to do about the warning is to suppress or ignore it.

Answer 3

If you specify the file path with a variable, there is a risk that an unintended file path will be specified. Therefore, you should use filepath.Clean() to clean up possible bad paths.

an easy solution:

f,err := os.Open(filepath.Clean(fname))

Answer 4

How do I solve the following warning from gosec linter:

::warning: Potential file inclusion via variable,MEDIUM,HIGH (gosec)

The linter is warning me on the first line of this function:

func File2lines(filePath string) ([]string, error) {
    f, err := os.Open(filePath) //Warning here
    if err != nil {
        return nil, err
    }
    defer f.Close()
    return linesFromReader(f)
}

I have tried reading up on local file inclusion, but cannot see how that would be applicable here.