122 lines
2.7 KiB
Go
122 lines
2.7 KiB
Go
package main
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// #include <sys/types.h>
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// #include <grp.h>
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// #include <pwd.h>
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// #include <stdlib.h>
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// #include <stdio.h>
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// #include <string.h>
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// typedef FILE * pFILE;
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import "C"
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import (
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"fmt"
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"os/user"
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"path/filepath"
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"sync"
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"syscall"
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"unsafe"
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"github.com/pkg/errors"
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)
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func fopenContainerFile(rootdir, filename string) (C.pFILE, error) {
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var st, lst syscall.Stat_t
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ctrfile := filepath.Join(rootdir, filename)
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cctrfile := C.CString(ctrfile)
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defer C.free(unsafe.Pointer(cctrfile))
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mode := C.CString("r")
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defer C.free(unsafe.Pointer(mode))
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f, err := C.fopen(cctrfile, mode)
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if f == nil || err != nil {
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return nil, errors.Wrapf(err, "error opening %q", ctrfile)
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}
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if err = syscall.Fstat(int(C.fileno(f)), &st); err != nil {
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return nil, errors.Wrapf(err, "fstat(%q)", ctrfile)
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}
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if err = syscall.Lstat(ctrfile, &lst); err != nil {
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return nil, errors.Wrapf(err, "lstat(%q)", ctrfile)
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}
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if st.Dev != lst.Dev || st.Ino != lst.Ino {
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return nil, errors.Errorf("%q is not a regular file", ctrfile)
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}
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return f, nil
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}
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var (
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lookupUser, lookupGroup sync.Mutex
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)
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func lookupUserInContainer(rootdir, username string) (uint64, uint64, error) {
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name := C.CString(username)
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defer C.free(unsafe.Pointer(name))
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f, err := fopenContainerFile(rootdir, "/etc/passwd")
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if err != nil {
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return 0, 0, err
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}
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defer C.fclose(f)
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lookupUser.Lock()
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defer lookupUser.Unlock()
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pwd := C.fgetpwent(f)
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for pwd != nil {
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if C.strcmp(pwd.pw_name, name) != 0 {
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pwd = C.fgetpwent(f)
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continue
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}
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return uint64(pwd.pw_uid), uint64(pwd.pw_gid), nil
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}
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return 0, 0, user.UnknownUserError(fmt.Sprintf("error looking up user %q", username))
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}
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func lookupGroupForUIDInContainer(rootdir string, userid uint64) (string, uint64, error) {
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f, err := fopenContainerFile(rootdir, "/etc/passwd")
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if err != nil {
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return "", 0, err
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}
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defer C.fclose(f)
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lookupUser.Lock()
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defer lookupUser.Unlock()
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pwd := C.fgetpwent(f)
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for pwd != nil {
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if uint64(pwd.pw_uid) != userid {
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pwd = C.fgetpwent(f)
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continue
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}
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return C.GoString(pwd.pw_name), uint64(pwd.pw_gid), nil
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}
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return "", 0, user.UnknownUserError(fmt.Sprintf("error looking up user with UID %d", userid))
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}
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func lookupGroupInContainer(rootdir, groupname string) (uint64, error) {
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name := C.CString(groupname)
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defer C.free(unsafe.Pointer(name))
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f, err := fopenContainerFile(rootdir, "/etc/group")
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if err != nil {
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return 0, err
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}
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defer C.fclose(f)
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lookupGroup.Lock()
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defer lookupGroup.Unlock()
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grp := C.fgetgrent(f)
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for grp != nil {
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if C.strcmp(grp.gr_name, name) != 0 {
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grp = C.fgetgrent(f)
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continue
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}
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return uint64(grp.gr_gid), nil
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}
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return 0, user.UnknownGroupError(fmt.Sprintf("error looking up group %q", groupname))
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}
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