8000 ssh: explicitly set ~ for home directory unless using cmd.exe (#1) · coder/mutagen@e72b7b9 · GitHub
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ssh: explicitly set ~ for home directory unless using cmd.exe (#1)
* docs: update security contact email Signed-off-by: Jacob Howard <jacob@mutagen.io> * ssh: explicitly set ~ for home directory unless using cmd.exe * ssh: add tests for explicit ~ * ssh: disable Docker transport tests * fixup: undo spurious character added * refactor path component logic into new function --------- Signed-off-by: Jacob Howard <jacob@mutagen.io> Co-authored-by: Jacob Howard <jacob@mutagen.io>
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‎.gitignore

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# Build output
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/build/
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.idea/

‎README.md

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@@ -66,7 +66,7 @@ If you'd like to contribute to Mutagen, please see the
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Mutagen takes security very seriously. If you believe you have found a security
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issue with Mutagen, please practice responsible disclosure practices and send an
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email directly to [security@mutagen.io](mailto:security@mutagen.io) instead of
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email directly to [security@docker.com](mailto:security@docker.com) instead of
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opening a GitHub issue. For more information, please see the
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[security documentation](SECURITY.md).
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If you find a security issue with Mutagen or one of its related projects, please
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DO NOT submit it via the issue tracker! Instead, please follow responsible
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disclosure practices and send information about security issues directly to
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[security@mutagen.io](mailto:security@mutagen.io) so that a proper assessment
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can be made and a fix prepared before a wide announcement. You will receive an
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acknowledgement within 24 hours. If you do not, please contact the project
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maintainer directly at [jacob@mutagen.io](mailto:jacob@mutagen.io).
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[security@docker.com](mailto:security@docker.com) so that a proper assessment
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can be made and a fix prepared before a wide announcement. Please note that the
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`@docker.com` email address is correct — Docker acquired Mutagen in 2023.
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Even in cases where you have limited or incomplete information, or you're not
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sure whether or not a problem constitutes a security issue, please make contact
Original file line numberDiff line numberDiff line change
@@ -34,39 +34,7 @@ const (
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// installation should be attempted and whether or not the remote environment is
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// cmd.exe-based.
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func connect(logger *logging.Logger, transport Transport, mode, prompter string, cmdExe bool) (io.ReadWriteCloser, bool, bool, error) {
37-
// Compute the agent invocation command, relative to the user's home
38-
// directory on the remote. Unless we have reason to assume that this is a
39-
// cmd.exe environment, we construct a path using forward slashes. This will
40-
// work for all POSIX systems and POSIX-like environments on Windows. If we
41-
// know we're hitting a cmd.exe environment, then we use backslashes,
42-
// otherwise the invocation won't work. Watching for cmd.exe to fail on
43-
// commands with forward slashes is actually the way that we detect cmd.exe
44-
// environments.
45-
//
46-
// HACK: We're assuming that none of these path components have spaces in
47-
// them, but since we control all of them, this is probably okay.
48-
//
49-
// HACK: When invoking on Windows systems (whether inside a POSIX
50-
// environment or cmd.exe), we can leave the "exe" suffix off the target
51-
// name. Fortunately this allows us to also avoid having to try the
52-
// combination of forward slashes + ".exe" for Windows POSIX environments.
53-
pathSeparator := "/"
54-
if cmdExe {
55-
pathSeparator = "\\"
56-
}
57-
dataDirectoryName := filesystem.MutagenDataDirectoryName
58-
if mutagen.DevelopmentModeEnabled {
59-
dataDirectoryName = filesystem.MutagenDataDirectoryDevelopmentName
60-
}
61-
agentInvocationPath := strings.Join([]string{
62-
dataDirectoryName,
63-
filesystem.MutagenAgentsDirectoryName,
64-
mutagen.Version,
65-
BaseName,
66-
}, pathSeparator)
67-
68-
// Compute the command to invoke.
69-
command := fmt.Sprintf("%s %s --%s=%s", agentInvocationPath, mode, FlagLogLevel, logger.Level())
37+
command := fmt.Sprintf("%s %s --%s=%s", agentInvocationPath(cmdExe), mode, FlagLogLevel, logger.Level())
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7139
// Set up (but do not start) an agent process.
7240
message := "Connecting to agent (POSIX)..."
@@ -176,6 +144,55 @@ func connect(logger *logging.Logger, transport Transport, mode, prompter string,
176144
return stream, false, false, nil
177145
}
178146

147+
// agentInvocationPath computes the agent invocation path, relative to the user's home
148+
// directory on the remote.
149+
func agentInvocationPath(cmdExe bool) string {
150+
dataDirectoryName := filesystem.MutagenDataDirectoryName
151+
if mutagen.DevelopmentModeEnabled {
152+
dataDirectoryName = filesystem.MutagenDataDirectoryDevelopmentName
153+
}
154+
return remotePathFromHome(cmdExe,
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dataDirectoryName,
156+
filesystem.MutagenAgentsDirectoryName,
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mutagen.Version,
158+
BaseName,
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)
160+
}
161+
162+
// remotePathFromHome constructs a path string from the given components as a list of relative path components from
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// the user's home directory. If cmdExe is true, construct a path cmd.exe will understand.
164+
func remotePathFromHome(cmdExe bool, components ...string) string {
165+
// Unless we have reason to assume that this is a cmd.exe environment, we
166+
// construct a path using forward slashes. This will work for all POSIX
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// systems and POSIX-like environments on Windows. If we know we're hitting
168+
// a cmd.exe environment, then we use backslashes, otherwise the invocation
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// won't work. Watching for cmd.exe to fail on commands with forward slashes
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// is actually the way that we detect cmd.exe environments.
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//
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// HACK: We're assuming that none of these path components have spaces in
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// them, but since we control all of them, this is probably okay.
174+
//
175+
// HACK: When invoking on Windows systems (whether inside a POSIX
176+
// environment or cmd.exe), we can leave the "exe" suffix off the target
177+
// name. Fortunately this allows us to also avoid having to try the
178+
// combination of forward slashes + ".exe" for Windows POSIX environments.
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//
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// HACK: When invoking on cmd.exe, we leave off the ~ prefix, since cmd.exe
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// doesn't recognize it. In most cases the initial working directory for SSH
182+
// commands is the home directory, but when possible we try to be explicit,
183+
// to work around systems that use a different directory, such as Coder
184+
// workspaces, which allow different initial working directories to be
185+
// configured.
186+
pathSeparator := "/"
187+
pathComponents := []string{filesystem.HomeDirectorySpecial}
188+
if cmdExe {
189+
pathSeparator = "\\"
190+
pathComponents = nil
191+
}
192+
pathComponents = append(pathComponents, components...)
193+
return strings.Join(pathComponents, pathSeparator)
194+
}
195+
179196
// Dial connects to an agent-based endpoint using the specified transport,
180197
// connection mode, and prompter.
181198
func Dial(logger *logging.Logger, transport Transport, mode, prompter string) (io.ReadWriteCloser, error) {
@@ -204,7 +221,7 @@ func Dial(logger *logging.Logger, transport Transport, mode, prompter string) (i
204221
}
205222

206223
// Attempt to install.
207-
if err := install(logger, transport, prompter); err != nil {
224+
if err := install(logger, transport, prompter, cmdExe); err != nil {
208225
return nil, fmt.Errorf("unable to install agent: %w", err)
209226
}
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@@ -1,3 +1,21 @@
11
package agent
22

3-
// TODO: Implement.
3+
import (
4+
"fmt"
5+
"github.com/mutagen-io/mutagen/pkg/mutagen"
6+
"testing"
7+
)
8+
9+
func TestAgentInvocationPath(t *testing.T) {
10+
path := agentInvocationPath(false)
11+
expected := fmt.Sprintf("~/.mutagen/agents/%s/mutagen-agent", mutagen.Version)
12+
if path != expected {
13+
t.Errorf("Invocation path cmdExe=false, expected %s, got %s", expected, path)
14+
}
15+
16+
path = agentInvocationPath(true)
17+
expected = fmt.Sprintf(".mutagen\\agents\\%s\\mutagen-agent", mutagen.Version)
18+
if path != expected {
19+
t.Errorf("Invocation path cmdExe=true, expected %s, got %s", expected, path)
20+
}
21+
}
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@@ -38,7 +38,7 @@ func Install() error {
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3939
// install attempts to probe an endpoint and install the appropriate agent
4040
// binary over the specified transport.
41-
func install(logger *logging.Logger, transport Transport, prompter string) error {
41+
func install(logger *logging.Logger, transport Transport, prompter string, cmdExe bool) error {
4242
// Detect the target platform.
4343
goos, goarch, posix, err := probe(transport, prompter)
4444
if err != nil {
@@ -68,14 +68,16 @@ func install(logger *logging.Logger, transport Transport, prompter string) error
6868
if err != nil {
6969
return fmt.Errorf("unable to generate UUID for agent copying: %w", err)
7070
}
71-
destination := BaseName + randomUUID.String()
71+
remoteFileName := BaseName + randomUUID.String()
7272
if goos == "windows" {
73-
destination += ".exe"
73+
remoteFileName += ".exe"
7474
}
7575
if posix {
76-
destination = "." + destination
76+
remoteFileName = "." + remoteFileName
7777
}
78-
if err = transport.Copy(agentExecutable, destination); err != nil {
78+
fullRemotePath := remotePathFromHome(cmdExe, remoteFileName)
79+
80+
if err = transport.Copy(agentExecutable, fullRemotePath); err != nil {
7981
return fmt.Errorf("unable to copy agent binary: %w", err)
8082
}
8183

@@ -89,7 +91,7 @@ func install(logger *logging.Logger, transport Transport, prompter string) error
8991
if err := prompting.Message(prompter, "Setting agent executability..."); err != nil {
9092
return fmt.Errorf("unable to message prompter: %w", err)
9193
}
92-
executabilityCommand := fmt.Sprintf("chmod +x %s", destination)
94+
executabilityCommand := fmt.Sprintf("chmod +x %s", fullRemotePath)
9395
if err := run(transport, executabilityCommand); err != nil {
9496
return fmt.Errorf("unable to set agent executability: %w", err)
9597
}
@@ -99,12 +101,7 @@ func install(logger *logging.Logger, transport Transport, prompter string) error
99101
if err := prompting.Message(prompter, "Installing agent..."); err != nil {
100102
return fmt.Errorf("unable to message prompter: %w", err)
101103
}
102-
var installCommand string
103-
if posix {
104-
installCommand = fmt.Sprintf("./%s %s", destination, CommandInstall)
105-
} else {
106-
installCommand = fmt.Sprintf("%s %s", destination, CommandInstall)
107-
}
104+
installCommand := fmt.Sprintf("%s %s", fullRemotePath, CommandInstall)
108105
if err := run(transport, installCommand); err != nil {
109106
return fmt.Errorf("unable to invoke agent installation: %w", err)
110107
}
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@@ -8,6 +8,7 @@ import (
88
"os/exec"
99
"path/filepath"
1010
"strconv"
11+
"strings"
1112

1213
"github.com/mutagen-io/mutagen/pkg/agent"
1314
"github.com/mutagen-io/mutagen/pkg/agent/transport"
@@ -192,6 +193,12 @@ func (t *sshTransport) Command(command string) (*exec.Cmd, error) {
192193

193194
// ClassifyError implements the ClassifyError method of agent.Transport.
194195
func (t *sshTransport) ClassifyError(processState *os.ProcessState, errorOutput string) (bool, bool, error) {
196+
// Windows Powershell introduces line breaks in the errorOutput, which get
197+
// escaped before arriving at this function into a literal `\r` followed by
198+
// a newline. Strip these out so that line breaks don't screw with our
199+
// matching.
200+
errorOutput = strings.ReplaceAll(errorOutput, "\\r\n", "")
201+
195202
// SSH faithfully returns exit codes and error output, so we can use direct
196203
// methods for testing and classification. Note that we may get POSIX-like
197204
// error codes back even from Windows remotes, but that indicates a POSIX
@@ -228,6 +235,10 @@ func (t *sshTransport) ClassifyError(processState *os.ProcessState, errorOutput
228235
return false, true, nil
229236
} else if process.OutputIsWindowsCommandNotFound(errorOutput) {
230237
return true, true, nil
238+
} else if process.OutputIsWindowsPowershellCommandNotFound(errorOutput) {
239+
// It's Windows Powershell, not cmd.exe, so try (re)installing, but set cmdExe
240+
// to false.
241+
return true, false, nil
231242
}
232243

233244
// Just bail if we weren't able to determine the nature of the error.
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@@ -66,6 +66,8 @@ const (
6666
// MutagenLicensingDirectoryName is the name of the licensing data directory
6767
// within the Mutagen data directory.
6868
MutagenLicensingDirectoryName = "licensing"
69+
70+
HomeDirectorySpecial = "~"
6971
)
7072

7173
// Mutagen computes (and optionally creates) subdirectories inside the Mutagen
Original file line numberDiff line numberDiff line change
@@ -332,6 +332,9 @@ func (t *testWindowsDockerTransportPrompter) Prompt(_ string) (string, error) {
332332
}
333333

334334
func TestSynchronizationGOROOTSrcToBetaOverDocker(t *testing.T) {
335+
// CODER: we don't care about Docker-based transport, and our SSH changes break it on Linux
336+
t.Skip()
337+
335338
// If Docker test support isn't available, then skip this test.
336339
if os.Getenv("MUTAGEN_TEST_DOCKER") != "true" {
337340
t.Skip()
@@ -422,6 +425,9 @@ func init() {
422425
}
423426

424427
func TestForwardingToHTTPDemo(t *testing.T) {
428+
// CODER: we don't care about Docker-based transport, and our SSH changes break it on Linux
429+
t.Skip()
430+
425431
// If Docker test support isn't available, then skip this test.
426432
if os.Getenv("MUTAGEN_TEST_DOCKER") != "true" {
427433
t.Skip()
Original file line numberDiff line numberDiff line change
@@ -20,6 +20,10 @@ const (
2020
// windowsCommandNotFoundFragment is a fragment of the error output returned
2121
// on Windows systems when a command cannot be found.
2222
windowsCommandNotFoundFragment = "The system cannot find the path specified"
23+
// windowsPowershellCommandNotFoundFragment is a fragment of the error output
24+
// returned on Windows systems running Powershell when a command cannot be
25+
// found.
26+
windowsPowershellCommandNotFoundFragment = "is not recognized as the name of a cmdlet, function, script file, or operable program."
2327
)
2428

2529
// OutputIsPOSIXCommandNotFound returns whether or not a process' error output
@@ -38,6 +42,13 @@ func OutputIsWindowsInvalidCommand(output string) bool {
3842
// represents a command not found error on Windows.
3943
func OutputIsWindowsCommandNotFound(output string) bool {
4044
return strings.Contains(output, windowsCommandNotFoundFragment)
45+
46+
}
47+
48+
// OutputIsWindowsPowershellCommandNotFound returns whether or not a process' error
49+
// output represents a command not found error from Windows running Powershell.
50+
func OutputIsWindowsPowershellCommandNotFound(output string) bool {
51+
return strings.Contains(output, windowsPowershellCommandNotFoundFragment)
4152
}
4253

4354
// ExtractExitErrorMessage is a utility function that will attempt to extract