fortify/internal/app/share.system.go
Ophestra Umiker df6fc298f6
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migrate to git.gensokyo.uk/security/fortify
Signed-off-by: Ophestra Umiker <cat@ophivana.moe>
2024-12-20 00:20:02 +09:00

78 lines
2.4 KiB
Go

package app
import (
"path"
"git.gensokyo.uk/security/fortify/acl"
"git.gensokyo.uk/security/fortify/internal/linux"
"git.gensokyo.uk/security/fortify/internal/system"
)
const (
shell = "SHELL"
)
// shareSystem queues various system-related actions
func (seal *appSeal) shareSystem() {
// ensure Share (e.g. `/tmp/fortify.%d`)
// acl is unnecessary as this directory is world executable
seal.sys.Ensure(seal.SharePath, 0711)
// ensure process-specific share (e.g. `/tmp/fortify.%d/%s`)
// acl is unnecessary as this directory is world executable
seal.share = path.Join(seal.SharePath, seal.id)
seal.sys.Ephemeral(system.Process, seal.share, 0711)
// ensure child tmpdir parent directory (e.g. `/tmp/fortify.%d/tmpdir`)
targetTmpdirParent := path.Join(seal.SharePath, "tmpdir")
seal.sys.Ensure(targetTmpdirParent, 0700)
seal.sys.UpdatePermType(system.User, targetTmpdirParent, acl.Execute)
// ensure child tmpdir (e.g. `/tmp/fortify.%d/tmpdir/%d`)
targetTmpdir := path.Join(targetTmpdirParent, seal.sys.user.as)
seal.sys.Ensure(targetTmpdir, 01700)
seal.sys.UpdatePermType(system.User, targetTmpdir, acl.Read, acl.Write, acl.Execute)
seal.sys.bwrap.Bind(targetTmpdir, "/tmp", false, true)
// mount tmpfs on inner shared directory (e.g. `/tmp/fortify.%d`)
seal.sys.bwrap.Tmpfs(seal.SharePath, 1*1024*1024)
}
func (seal *appSeal) sharePasswd(os linux.System) {
// look up shell
sh := "/bin/sh"
if s, ok := os.LookupEnv(shell); ok {
seal.sys.bwrap.SetEnv[shell] = s
sh = s
}
// generate /etc/passwd
passwdPath := path.Join(seal.share, "passwd")
username := "chronos"
if seal.sys.user.username != "" {
username = seal.sys.user.username
}
homeDir := "/var/empty"
if seal.sys.user.home != "" {
homeDir = seal.sys.user.home
}
// bind home directory
seal.sys.bwrap.Bind(seal.sys.user.data, homeDir, false, true)
seal.sys.bwrap.Chdir = homeDir
seal.sys.bwrap.SetEnv["USER"] = username
seal.sys.bwrap.SetEnv["HOME"] = homeDir
passwd := username + ":x:" + seal.sys.mappedIDString + ":" + seal.sys.mappedIDString + ":Fortify:" + homeDir + ":" + sh + "\n"
seal.sys.Write(passwdPath, passwd)
// write /etc/group
groupPath := path.Join(seal.share, "group")
seal.sys.Write(groupPath, "fortify:x:"+seal.sys.mappedIDString+":\n")
// bind /etc/passwd and /etc/group
seal.sys.bwrap.Bind(passwdPath, "/etc/passwd")
seal.sys.bwrap.Bind(groupPath, "/etc/group")
}