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authorOphestra <cat@gensokyo.uk>2025-02-08 13:03:45 +0900
committerOphestra <cat@gensokyo.uk>2025-02-08 13:03:45 +0900
commite14923ae530dda0601c204fe17ac1956f54a45b0 (patch)
tree1578bbc4c08d9afc94c4b009cd2bf64260574f05 /internal/proc/priv/shim/main.go
parent7aff3ead3afaa7461e0054fbef23fb571b4add0a (diff)
helper/proc: move package out of internal
Signed-off-by: Ophestra <cat@gensokyo.uk>
Diffstat (limited to 'internal/proc/priv/shim/main.go')
-rw-r--r--internal/proc/priv/shim/main.go156
1 files changed, 0 insertions, 156 deletions
diff --git a/internal/proc/priv/shim/main.go b/internal/proc/priv/shim/main.go
deleted file mode 100644
index 7ad0a44b..00000000
--- a/internal/proc/priv/shim/main.go
+++ /dev/null
@@ -1,156 +0,0 @@
-package shim
-
-import (
- "errors"
- "os"
- "path"
- "strconv"
-
- "git.gensokyo.uk/security/fortify/fst"
- "git.gensokyo.uk/security/fortify/helper"
- "git.gensokyo.uk/security/fortify/helper/seccomp"
- "git.gensokyo.uk/security/fortify/internal"
- "git.gensokyo.uk/security/fortify/internal/fmsg"
- "git.gensokyo.uk/security/fortify/internal/proc"
- init0 "git.gensokyo.uk/security/fortify/internal/proc/priv/init"
-)
-
-// everything beyond this point runs as unconstrained target user
-// proceed with caution!
-
-func Main() {
- // sharing stdout with fortify
- // USE WITH CAUTION
- fmsg.SetPrefix("shim")
-
- // setting this prevents ptrace
- if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
- fmsg.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
- panic("unreachable")
- }
-
- // receive setup payload
- var (
- payload Payload
- closeSetup func() error
- )
- if f, err := proc.Receive(Env, &payload); err != nil {
- if errors.Is(err, proc.ErrInvalid) {
- fmsg.Fatal("invalid config descriptor")
- }
- if errors.Is(err, proc.ErrNotSet) {
- fmsg.Fatal("FORTIFY_SHIM not set")
- }
-
- fmsg.Fatalf("cannot decode shim setup payload: %v", err)
- panic("unreachable")
- } else {
- fmsg.SetVerbose(payload.Verbose)
- closeSetup = f
- }
-
- if payload.Bwrap == nil {
- fmsg.Fatal("bwrap config not supplied")
- }
-
- // restore bwrap sync fd
- var syncFd *os.File
- if payload.Sync != nil {
- syncFd = os.NewFile(*payload.Sync, "sync")
- }
-
- // close setup socket
- if err := closeSetup(); err != nil {
- fmsg.Println("cannot close setup pipe:", err)
- // not fatal
- }
-
- // ensure home directory as target user
- if s, err := os.Stat(payload.Home); err != nil {
- if os.IsNotExist(err) {
- if err = os.Mkdir(payload.Home, 0700); err != nil {
- fmsg.Fatalf("cannot create home directory: %v", err)
- }
- } else {
- fmsg.Fatalf("cannot access home directory: %v", err)
- }
-
- // home directory is created, proceed
- } else if !s.IsDir() {
- fmsg.Fatalf("data path %q is not a directory", payload.Home)
- }
-
- var ic init0.Payload
-
- // resolve argv0
- ic.Argv = payload.Argv
- if len(ic.Argv) > 0 {
- // looked up from $PATH by parent
- ic.Argv0 = payload.Exec[1]
- } else {
- // no argv, look up shell instead
- var ok bool
- if payload.Bwrap.SetEnv == nil {
- fmsg.Fatal("no command was specified and environment is unset")
- }
- if ic.Argv0, ok = payload.Bwrap.SetEnv["SHELL"]; !ok {
- fmsg.Fatal("no command was specified and $SHELL was unset")
- }
-
- ic.Argv = []string{ic.Argv0}
- }
-
- conf := payload.Bwrap
-
- var extraFiles []*os.File
-
- // serve setup payload
- if fd, encoder, err := proc.Setup(&extraFiles); err != nil {
- fmsg.Fatalf("cannot pipe: %v", err)
- } else {
- conf.SetEnv[init0.Env] = strconv.Itoa(fd)
- go func() {
- fmsg.VPrintln("transmitting config to init")
- if err = encoder.Encode(&ic); err != nil {
- fmsg.Fatalf("cannot transmit init config: %v", err)
- }
- }()
- }
-
- // bind fortify inside sandbox
- var (
- innerSbin = path.Join(fst.Tmp, "sbin")
- innerFortify = path.Join(innerSbin, "fortify")
- innerInit = path.Join(innerSbin, "init")
- )
- conf.Bind(proc.MustExecutable(), innerFortify)
- conf.Symlink("fortify", innerInit)
-
- helper.BubblewrapName = payload.Exec[0] // resolved bwrap path by parent
- if fmsg.Verbose() {
- seccomp.CPrintln = fmsg.Println
- }
- if b, err := helper.NewBwrap(
- conf, innerInit,
- nil, func(int, int) []string { return make([]string, 0) },
- extraFiles,
- syncFd,
- ); err != nil {
- fmsg.Fatalf("malformed sandbox config: %v", err)
- } else {
- cmd := b.Unwrap()
- cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
-
- // run and pass through exit code
- if err = b.Start(); err != nil {
- fmsg.Fatalf("cannot start target process: %v", err)
- } else if err = b.Wait(); err != nil {
- fmsg.VPrintln("wait:", err)
- }
- if b.Unwrap().ProcessState != nil {
- fmsg.Exit(b.Unwrap().ProcessState.ExitCode())
- } else {
- fmsg.Exit(127)
- }
- }
-}