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Refactor git command package to improve security and maintainability (#22678)

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This PR follows #21535 (and replace #22592)

## Review without space diff

https://github.com/go-gitea/gitea/pull/22678/files?diff=split&w=1

## Purpose of this PR

1. Make git module command completely safe (risky user inputs won't be
passed as argument option anymore)
2. Avoid low-level mistakes like
https://github.com/go-gitea/gitea/pull/22098#discussion_r1045234918
3. Remove deprecated and dirty `CmdArgCheck` function, hide the `CmdArg`
type
4. Simplify code when using git command

## The main idea of this PR

* Move the `git.CmdArg` to the `internal` package, then no other package
except `git` could use it. Then developers could never do
`AddArguments(git.CmdArg(userInput))` any more.
* Introduce `git.ToTrustedCmdArgs`, it's for user-provided and already
trusted arguments. It's only used in a few cases, for example: use git
arguments from config file, help unit test with some arguments.
* Introduce `AddOptionValues` and `AddOptionFormat`, they make code more
clear and simple:
    * Before: `AddArguments("-m").AddDynamicArguments(message)`
    * After: `AddOptionValues("-m", message)`
    * -
* Before: `AddArguments(git.CmdArg(fmt.Sprintf("--author='%s <%s>'",
sig.Name, sig.Email)))`
* After: `AddOptionFormat("--author='%s <%s>'", sig.Name, sig.Email)`

## FAQ

### Why these changes were not done in #21535 ?

#21535 is mainly a search&replace, it did its best to not change too
much logic.

Making the framework better needs a lot of changes, so this separate PR
is needed as the second step.


### The naming of `AddOptionXxx`

According to git's manual, the `--xxx` part is called `option`.

### How can it guarantee that `internal.CmdArg` won't be not misused?

Go's specification guarantees that. Trying to access other package's
internal package causes compilation error.

And, `golangci-lint` also denies the git/internal package. Only the
`git/command.go` can use it carefully.

### There is still a `ToTrustedCmdArgs`, will it still allow developers
to make mistakes and pass untrusted arguments?

Generally speaking, no. Because when using `ToTrustedCmdArgs`, the code
will be very complex (see the changes for examples). Then developers and
reviewers can know that something might be unreasonable.

### Why there was a `CmdArgCheck` and why it's removed?

At the moment of #21535, to reduce unnecessary changes, `CmdArgCheck`
was introduced as a hacky patch. Now, almost all code could be written
as `cmd := NewCommand(); cmd.AddXxx(...)`, then there is no need for
`CmdArgCheck` anymore.


### Why many codes for `signArg == ""` is deleted?

Because in the old code, `signArg` could never be empty string, it's
either `-S[key-id]` or `--no-gpg-sign`. So the `signArg == ""` is just
dead code.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
This commit is contained in:
wxiaoguang 2023-02-04 10:30:43 +08:00 • committed by GitHub
parent 3c5655ce18
commit 6bc3079c00
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GPG key ID: 4AEE18F83AFDEB23
42 changed files with 382 additions and 385 deletions
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97
modules/git/command.go
View file

@ -16,14 +16,20 @@ import (
"time"
"unsafe"
"code.gitea.io/gitea/modules/git/internal" //nolint:depguard // only this file can use the internal type CmdArg, other files and packages should use AddXxx functions
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/process"
"code.gitea.io/gitea/modules/util"
)
// TrustedCmdArgs returns the trusted arguments for git command.
// It's mainly for passing user-provided and trusted arguments to git command
// In most cases, it shouldn't be used. Use AddXxx function instead
type TrustedCmdArgs []internal.CmdArg
var (
// globalCommandArgs global command args for external package setting
globalCommandArgs []CmdArg
globalCommandArgs TrustedCmdArgs
// defaultCommandExecutionTimeout default command execution timeout duration
defaultCommandExecutionTimeout = 360 * time.Second
@ -42,8 +48,6 @@ type Command struct {
brokenArgs []string
}
type CmdArg string
func (c *Command) String() string {
if len(c.args) == 0 {
return c.name
@ -53,7 +57,7 @@ func (c *Command) String() string {
// NewCommand creates and returns a new Git Command based on given command and arguments.
// Each argument should be safe to be trusted. User-provided arguments should be passed to AddDynamicArguments instead.
func NewCommand(ctx context.Context, args ...CmdArg) *Command {
func NewCommand(ctx context.Context, args ...internal.CmdArg) *Command {
// Make an explicit copy of globalCommandArgs, otherwise append might overwrite it
cargs := make([]string, 0, len(globalCommandArgs)+len(args))
for _, arg := range globalCommandArgs {
@ -70,15 +74,9 @@ func NewCommand(ctx context.Context, args ...CmdArg) *Command {
}
}
// NewCommandNoGlobals creates and returns a new Git Command based on given command and arguments only with the specify args and don't care global command args
// Each argument should be safe to be trusted. User-provided arguments should be passed to AddDynamicArguments instead.
func NewCommandNoGlobals(args ...CmdArg) *Command {
return NewCommandContextNoGlobals(DefaultContext, args...)
}
// NewCommandContextNoGlobals creates and returns a new Git Command based on given command and arguments only with the specify args and don't care global command args
// Each argument should be safe to be trusted. User-provided arguments should be passed to AddDynamicArguments instead.
func NewCommandContextNoGlobals(ctx context.Context, args ...CmdArg) *Command {
func NewCommandContextNoGlobals(ctx context.Context, args ...internal.CmdArg) *Command {
cargs := make([]string, 0, len(args))
for _, arg := range args {
cargs = append(cargs, string(arg))
@ -96,27 +94,70 @@ func (c *Command) SetParentContext(ctx context.Context) *Command {
return c
}
// SetDescription sets the description for this command which be returned on
// c.String()
// SetDescription sets the description for this command which be returned on c.String()
func (c *Command) SetDescription(desc string) *Command {
c.desc = desc
return c
}
// AddArguments adds new git argument(s) to the command. Each argument must be safe to be trusted.
// User-provided arguments should be passed to AddDynamicArguments instead.
func (c *Command) AddArguments(args ...CmdArg) *Command {
// isSafeArgumentValue checks if the argument is safe to be used as a value (not an option)
func isSafeArgumentValue(s string) bool {
return s == "" || s[0] != '-'
}
// isValidArgumentOption checks if the argument is a valid option (starting with '-').
// It doesn't check whether the option is supported or not
func isValidArgumentOption(s string) bool {
return s != "" && s[0] == '-'
}
// AddArguments adds new git arguments (option/value) to the command. It only accepts string literals, or trusted CmdArg.
// Type CmdArg is in the internal package, so it can not be used outside of this package directly,
// it makes sure that user-provided arguments won't cause RCE risks.
// User-provided arguments should be passed by other AddXxx functions
func (c *Command) AddArguments(args ...internal.CmdArg) *Command {
for _, arg := range args {
c.args = append(c.args, string(arg))
}
return c
}
// AddDynamicArguments adds new dynamic argument(s) to the command.
// The arguments may come from user input and can not be trusted, so no leading '-' is allowed to avoid passing options
// AddOptionValues adds a new option with a list of non-option values
// For example: AddOptionValues("--opt", val) means 2 arguments: {"--opt", val}.
// The values are treated as dynamic argument values. It equals to: AddArguments("--opt") then AddDynamicArguments(val).
func (c *Command) AddOptionValues(opt internal.CmdArg, args ...string) *Command {
if !isValidArgumentOption(string(opt)) {
c.brokenArgs = append(c.brokenArgs, string(opt))
return c
}
c.args = append(c.args, string(opt))
c.AddDynamicArguments(args...)
return c
}
// AddOptionFormat adds a new option with a format string and arguments
// For example: AddOptionFormat("--opt=%s %s", val1, val2) means 1 argument: {"--opt=val1 val2"}.
func (c *Command) AddOptionFormat(opt string, args ...any) *Command {
if !isValidArgumentOption(opt) {
c.brokenArgs = append(c.brokenArgs, opt)
return c
}
// a quick check to make sure the format string matches the number of arguments, to find low-level mistakes ASAP
if strings.Count(strings.ReplaceAll(opt, "%%", ""), "%") != len(args) {
c.brokenArgs = append(c.brokenArgs, opt)
return c
}
s := fmt.Sprintf(opt, args...)
c.args = append(c.args, s)
return c
}
// AddDynamicArguments adds new dynamic argument values to the command.
// The arguments may come from user input and can not be trusted, so no leading '-' is allowed to avoid passing options.
// TODO: in the future, this function can be renamed to AddArgumentValues
func (c *Command) AddDynamicArguments(args ...string) *Command {
for _, arg := range args {
if arg != "" && arg[0] == '-' {
if !isSafeArgumentValue(arg) {
c.brokenArgs = append(c.brokenArgs, arg)
}
}
@ -137,14 +178,14 @@ func (c *Command) AddDashesAndList(list ...string) *Command {
return c
}
// CmdArgCheck checks whether the string is safe to be used as a dynamic argument.
// It panics if the check fails. Usually it should not be used, it's just for refactoring purpose
// deprecated
func CmdArgCheck(s string) CmdArg {
if s != "" && s[0] == '-' {
panic("invalid git cmd argument: " + s)
// ToTrustedCmdArgs converts a list of strings (trusted as argument) to TrustedCmdArgs
// In most cases, it shouldn't be used. Use AddXxx function instead
func ToTrustedCmdArgs(args []string) TrustedCmdArgs {
ret := make(TrustedCmdArgs, len(args))
for i, arg := range args {
ret[i] = internal.CmdArg(arg)
}
return CmdArg(s)
return ret
}
// RunOpts represents parameters to run the command. If UseContextTimeout is specified, then Timeout is ignored.
@ -364,9 +405,9 @@ func (c *Command) RunStdBytes(opts *RunOpts) (stdout, stderr []byte, runErr RunS
}
// AllowLFSFiltersArgs return globalCommandArgs with lfs filter, it should only be used for tests
func AllowLFSFiltersArgs() []CmdArg {
func AllowLFSFiltersArgs() TrustedCmdArgs {
// Now here we should explicitly allow lfs filters to run
filteredLFSGlobalArgs := make([]CmdArg, len(globalCommandArgs))
filteredLFSGlobalArgs := make(TrustedCmdArgs, len(globalCommandArgs))
j := 0
for _, arg := range globalCommandArgs {
if strings.Contains(string(arg), "lfs") {