the "golang.org/x/sys/execabs" package was introduced to address a security
issue on Windows, and changing the default behavior of os/exec was considered
a breaking change. go1.19 applied the behavior that was previously implemented
in the execabs package;
from the release notes: https://go.dev/doc/go1.19#os-exec-path
> Command and LookPath no longer allow results from a PATH search to be found
> relative to the current directory. This removes a common source of security
> problems but may also break existing programs that depend on using, say,
> exec.Command("prog") to run a binary named prog (or, on Windows, prog.exe)
> in the current directory. See the os/exec package documentation for information
> about how best to update such programs.
>
> On Windows, Command and LookPath now respect the NoDefaultCurrentDirectoryInExePath
> environment variable, making it possible to disable the default implicit search
> of “.” in PATH lookups on Windows systems.
With those changes, we no longer need to use the execabs package, and we can
switch back to os/exec.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
On Windows, the os/exec.{Command,CommandContext,LookPath} functions
resolve command names that have neither path separators nor file extension
(e.g., "git") by first looking in the current working directory before
looking in the PATH environment variable.
Go maintainers intended to match cmd.exe's historical behavior.
However, this is pretty much never the intended behavior and as an abundance of precaution
this patch prevents that when executing commands.
Example of commands that docker.exe may execute: `git`, `docker-buildx` (or other cli plugin), `docker-credential-wincred`, `docker`.
Note that this was prompted by the [Go 1.15.7 security fixes](https://blog.golang.org/path-security), but unlike in `go.exe`,
the windows path lookups in docker are not in a code path allowing remote code execution, thus there is no security impact on docker.
Signed-off-by: Tibor Vass <tibor@docker.com>
Also includes the scaffolding for finding a validating plugin candidates.
Argument validation is moved to RunE to support this, so `noArgs` is removed.
Signed-off-by: Ian Campbell <ijc@docker.com>
Sebastiaan van Stijn
Tibor Vass
Ian Campbell