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gvisor: lockless read access for task credentials 

Credentials are immutable and even before these changes we could read them
without locks, but we needed to take a task lock to get a credential object
from a task object.

It is possible to avoid this lock, if we will guarantee that a credential
object will not be changed after setting it on a task.

PiperOrigin-RevId: 254989492
This commit is contained in:
Andrei Vagin 2019-06-25 09:51:36 -07:00 committed by gVisor bot
parent fd16a329ce
commit 03ae91c662
7 changed files with 159 additions and 113 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
pkg/sentry/kernel/auth/BUILD
View File

@ -3,6 +3,17 @@ package(licenses = ["notice"])
load("//tools/go_generics:defs.bzl", "go_template_instance")
load("//tools/go_stateify:defs.bzl", "go_library")
go_template_instance(
name = "atomicptr_credentials",
out = "atomicptr_credentials.go",
package = "auth",
suffix = "Credentials",
template = "//third_party/gvsync:generic_atomicptr",
types = {
"Value": "Credentials",
},
)
go_template_instance(
name = "id_map_range",
out = "id_map_range.go",
@ -34,6 +45,7 @@ go_template_instance(
go_library(
name = "auth",
srcs = [
"atomicptr_credentials.go",
"auth.go",
"capability_set.go",
"context.go",

11
pkg/sentry/kernel/task.go
View File

@ -386,10 +386,11 @@ type Task struct {
// creds is the task's credentials.
//
// creds is protected by mu, however the value itself is immutable and can
// only be changed by a copy. After reading the pointer, access will
// proceed outside the scope of mu. creds is owned by the task goroutine.
creds *auth.Credentials
// creds.Load() may be called without synchronization. creds.Store() is
// serialized by mu. creds is owned by the task goroutine. All
// auth.Credentials objects that creds may point to, or have pointed to
// in the past, must be treated as immutable.
creds auth.AtomicPtrCredentials
// utsns is the task's UTS namespace.
//
@ -597,7 +598,7 @@ func (t *Task) Value(key interface{}) interface{} {
case CtxTask:
return t
case auth.CtxCredentials:
return t.creds
return t.Credentials()
case context.CtxThreadGroupID:
return int32(t.ThreadGroup().ID())
case fs.CtxRoot:

9
pkg/sentry/kernel/task_clone.go
View File

@ -425,6 +425,7 @@ func (t *Task) Unshare(opts *SharingOptions) error {
if opts.NewAddressSpace || opts.NewSignalHandlers {
return syserror.EINVAL
}
creds := t.Credentials()
if opts.NewThreadGroup {
t.tg.signalHandlers.mu.Lock()
if t.tg.tasksCount != 1 {
@ -439,8 +440,6 @@ func (t *Task) Unshare(opts *SharingOptions) error {
if t.IsChrooted() {
return syserror.EPERM
}
// This temporary is needed because Go.
creds := t.Credentials()
newUserNS, err := creds.NewChildUserNamespace()
if err != nil {
return err
@ -449,6 +448,8 @@ func (t *Task) Unshare(opts *SharingOptions) error {
if err != nil {
return err
}
// Need to reload creds, becaue t.SetUserNamespace() changed task credentials.
creds = t.Credentials()
}
haveCapSysAdmin := t.HasCapability(linux.CAP_SYS_ADMIN)
if opts.NewPIDNamespace {
@ -473,7 +474,7 @@ func (t *Task) Unshare(opts *SharingOptions) error {
}
// Note that this must happen after NewUserNamespace, so the
// new user namespace is used if there is one.
t.utsns = t.utsns.Clone(t.creds.UserNamespace)
t.utsns = t.utsns.Clone(creds.UserNamespace)
}
if opts.NewIPCNamespace {
if !haveCapSysAdmin {
@ -482,7 +483,7 @@ func (t *Task) Unshare(opts *SharingOptions) error {
}
// Note that "If CLONE_NEWIPC is set, then create the process in a new IPC
// namespace"
t.ipcns = NewIPCNamespace(t.creds.UserNamespace)
t.ipcns = NewIPCNamespace(creds.UserNamespace)
}
var oldfds *FDMap
if opts.NewFiles {

220
pkg/sentry/kernel/task_identity.go
View File

@ -25,30 +25,22 @@ import (
//
// This value must be considered immutable.
func (t *Task) Credentials() *auth.Credentials {
t.mu.Lock()
defer t.mu.Unlock()
return t.creds
return t.creds.Load()
}
// UserNamespace returns the user namespace associated with the task.
func (t *Task) UserNamespace() *auth.UserNamespace {
t.mu.Lock()
defer t.mu.Unlock()
return t.creds.UserNamespace
return t.Credentials().UserNamespace
}
// HasCapabilityIn checks if the task has capability cp in user namespace ns.
func (t *Task) HasCapabilityIn(cp linux.Capability, ns *auth.UserNamespace) bool {
t.mu.Lock()
defer t.mu.Unlock()
return t.creds.HasCapabilityIn(cp, ns)
return t.Credentials().HasCapabilityIn(cp, ns)
}
// HasCapability checks if the task has capability cp in its user namespace.
func (t *Task) HasCapability(cp linux.Capability) bool {
t.mu.Lock()
defer t.mu.Unlock()
return t.creds.HasCapability(cp)
return t.Credentials().HasCapability(cp)
}
// SetUID implements the semantics of setuid(2).
@ -57,9 +49,12 @@ func (t *Task) SetUID(uid auth.UID) error {
if !uid.Ok() {
return syserror.EINVAL
}
t.mu.Lock()
defer t.mu.Unlock()
kuid := t.creds.UserNamespace.MapToKUID(uid)
creds := t.Credentials()
kuid := creds.UserNamespace.MapToKUID(uid)
if !kuid.Ok() {
return syserror.EINVAL
}
@ -67,17 +62,17 @@ func (t *Task) SetUID(uid auth.UID) error {
// effective UID of the caller is root (more precisely: if the caller has
// the CAP_SETUID capability), the real UID and saved set-user-ID are also
// set." - setuid(2)
if t.creds.HasCapability(linux.CAP_SETUID) {
if creds.HasCapability(linux.CAP_SETUID) {
t.setKUIDsUncheckedLocked(kuid, kuid, kuid)
return nil
}
// "EPERM: The user is not privileged (Linux: does not have the CAP_SETUID
// capability) and uid does not match the real UID or saved set-user-ID of
// the calling process."
if kuid != t.creds.RealKUID && kuid != t.creds.SavedKUID {
if kuid != creds.RealKUID && kuid != creds.SavedKUID {
return syserror.EPERM
}
t.setKUIDsUncheckedLocked(t.creds.RealKUID, kuid, t.creds.SavedKUID)
t.setKUIDsUncheckedLocked(creds.RealKUID, kuid, creds.SavedKUID)
return nil
}
@ -87,37 +82,38 @@ func (t *Task) SetREUID(r, e auth.UID) error {
defer t.mu.Unlock()
// "Supplying a value of -1 for either the real or effective user ID forces
// the system to leave that ID unchanged." - setreuid(2)
newR := t.creds.RealKUID
creds := t.Credentials()
newR := creds.RealKUID
if r.Ok() {
newR = t.creds.UserNamespace.MapToKUID(r)
newR = creds.UserNamespace.MapToKUID(r)
if !newR.Ok() {
return syserror.EINVAL
}
}
newE := t.creds.EffectiveKUID
newE := creds.EffectiveKUID
if e.Ok() {
newE = t.creds.UserNamespace.MapToKUID(e)
newE = creds.UserNamespace.MapToKUID(e)
if !newE.Ok() {
return syserror.EINVAL
}
}
if !t.creds.HasCapability(linux.CAP_SETUID) {
if !creds.HasCapability(linux.CAP_SETUID) {
// "Unprivileged processes may only set the effective user ID to the
// real user ID, the effective user ID, or the saved set-user-ID."
if newE != t.creds.RealKUID && newE != t.creds.EffectiveKUID && newE != t.creds.SavedKUID {
if newE != creds.RealKUID && newE != creds.EffectiveKUID && newE != creds.SavedKUID {
return syserror.EPERM
}
// "Unprivileged users may only set the real user ID to the real user
// ID or the effective user ID."
if newR != t.creds.RealKUID && newR != t.creds.EffectiveKUID {
if newR != creds.RealKUID && newR != creds.EffectiveKUID {
return syserror.EPERM
}
}
// "If the real user ID is set (i.e., ruid is not -1) or the effective user
// ID is set to a value not equal to the previous real user ID, the saved
// set-user-ID will be set to the new effective user ID."
newS := t.creds.SavedKUID
if r.Ok() || (e.Ok() && newE != t.creds.EffectiveKUID) {
newS := creds.SavedKUID
if r.Ok() || (e.Ok() && newE != creds.EffectiveKUID) {
newS = newE
}
t.setKUIDsUncheckedLocked(newR, newE, newS)
@ -136,23 +132,24 @@ func (t *Task) SetRESUID(r, e, s auth.UID) error {
// arguments equals -1, the corresponding value is not changed." -
// setresuid(2)
var err error
newR := t.creds.RealKUID
creds := t.Credentials()
newR := creds.RealKUID
if r.Ok() {
newR, err = t.creds.UseUID(r)
newR, err = creds.UseUID(r)
if err != nil {
return err
}
}
newE := t.creds.EffectiveKUID
newE := creds.EffectiveKUID
if e.Ok() {
newE, err = t.creds.UseUID(e)
newE, err = creds.UseUID(e)
if err != nil {
return err
}
}
newS := t.creds.SavedKUID
newS := creds.SavedKUID
if s.Ok() {
newS, err = t.creds.UseUID(s)
newS, err = creds.UseUID(s)
if err != nil {
return err
}
@ -163,10 +160,10 @@ func (t *Task) SetRESUID(r, e, s auth.UID) error {
// Preconditions: t.mu must be locked.
func (t *Task) setKUIDsUncheckedLocked(newR, newE, newS auth.KUID) {
root := t.creds.UserNamespace.MapToKUID(auth.RootUID)
oldR, oldE, oldS := t.creds.RealKUID, t.creds.EffectiveKUID, t.creds.SavedKUID
t.creds = t.creds.Fork() // See doc for creds.
t.creds.RealKUID, t.creds.EffectiveKUID, t.creds.SavedKUID = newR, newE, newS
creds := t.Credentials().Fork() // The credentials object is immutable. See doc for creds.
root := creds.UserNamespace.MapToKUID(auth.RootUID)
oldR, oldE, oldS := creds.RealKUID, creds.EffectiveKUID, creds.SavedKUID
creds.RealKUID, creds.EffectiveKUID, creds.SavedKUID = newR, newE, newS
// "1. If one or more of the real, effective or saved set user IDs was
// previously 0, and as a result of the UID changes all of these IDs have a
@ -184,9 +181,9 @@ func (t *Task) setKUIDsUncheckedLocked(newR, newE, newS auth.KUID) {
// being cleared." (A thread's effective capability set is always
// cleared when such a credential change is made,
// regardless of the setting of the "keep capabilities" flag.)
if !t.creds.KeepCaps {
t.creds.PermittedCaps = 0
t.creds.EffectiveCaps = 0
if !creds.KeepCaps {
creds.PermittedCaps = 0
creds.EffectiveCaps = 0
}
}
// """
@ -197,9 +194,9 @@ func (t *Task) setKUIDsUncheckedLocked(newR, newE, newS auth.KUID) {
// permitted set is copied to the effective set.
// """
if oldE == root && newE != root {
t.creds.EffectiveCaps = 0
creds.EffectiveCaps = 0
} else if oldE != root && newE == root {
t.creds.EffectiveCaps = t.creds.PermittedCaps
creds.EffectiveCaps = creds.PermittedCaps
}
// "4. If the filesystem user ID is changed from 0 to nonzero (see
// setfsuid(2)), then the following capabilities are cleared from the
@ -220,6 +217,7 @@ func (t *Task) setKUIDsUncheckedLocked(newR, newE, newS auth.KUID) {
// Not documented, but compare Linux's kernel/cred.c:commit_creds().
t.parentDeathSignal = 0
}
t.creds.Store(creds)
}
// SetGID implements the semantics of setgid(2).
@ -227,20 +225,23 @@ func (t *Task) SetGID(gid auth.GID) error {
if !gid.Ok() {
return syserror.EINVAL
}
t.mu.Lock()
defer t.mu.Unlock()
kgid := t.creds.UserNamespace.MapToKGID(gid)
creds := t.Credentials()
kgid := creds.UserNamespace.MapToKGID(gid)
if !kgid.Ok() {
return syserror.EINVAL
}
if t.creds.HasCapability(linux.CAP_SETGID) {
if creds.HasCapability(linux.CAP_SETGID) {
t.setKGIDsUncheckedLocked(kgid, kgid, kgid)
return nil
}
if kgid != t.creds.RealKGID && kgid != t.creds.SavedKGID {
if kgid != creds.RealKGID && kgid != creds.SavedKGID {
return syserror.EPERM
}
t.setKGIDsUncheckedLocked(t.creds.RealKGID, kgid, t.creds.SavedKGID)
t.setKGIDsUncheckedLocked(creds.RealKGID, kgid, creds.SavedKGID)
return nil
}
@ -248,30 +249,32 @@ func (t *Task) SetGID(gid auth.GID) error {
func (t *Task) SetREGID(r, e auth.GID) error {
t.mu.Lock()
defer t.mu.Unlock()
newR := t.creds.RealKGID
creds := t.Credentials()
newR := creds.RealKGID
if r.Ok() {
newR = t.creds.UserNamespace.MapToKGID(r)
newR = creds.UserNamespace.MapToKGID(r)
if !newR.Ok() {
return syserror.EINVAL
}
}
newE := t.creds.EffectiveKGID
newE := creds.EffectiveKGID
if e.Ok() {
newE = t.creds.UserNamespace.MapToKGID(e)
newE = creds.UserNamespace.MapToKGID(e)
if !newE.Ok() {
return syserror.EINVAL
}
}
if !t.creds.HasCapability(linux.CAP_SETGID) {
if newE != t.creds.RealKGID && newE != t.creds.EffectiveKGID && newE != t.creds.SavedKGID {
if !creds.HasCapability(linux.CAP_SETGID) {
if newE != creds.RealKGID && newE != creds.EffectiveKGID && newE != creds.SavedKGID {
return syserror.EPERM
}
if newR != t.creds.RealKGID && newR != t.creds.EffectiveKGID {
if newR != creds.RealKGID && newR != creds.EffectiveKGID {
return syserror.EPERM
}
}
newS := t.creds.SavedKGID
if r.Ok() || (e.Ok() && newE != t.creds.EffectiveKGID) {
newS := creds.SavedKGID
if r.Ok() || (e.Ok() && newE != creds.EffectiveKGID) {
newS = newE
}
t.setKGIDsUncheckedLocked(newR, newE, newS)
@ -280,26 +283,29 @@ func (t *Task) SetREGID(r, e auth.GID) error {
// SetRESGID implements the semantics of the setresgid(2) syscall.
func (t *Task) SetRESGID(r, e, s auth.GID) error {
var err error
t.mu.Lock()
defer t.mu.Unlock()
var err error
newR := t.creds.RealKGID
creds := t.Credentials()
newR := creds.RealKGID
if r.Ok() {
newR, err = t.creds.UseGID(r)
newR, err = creds.UseGID(r)
if err != nil {
return err
}
}
newE := t.creds.EffectiveKGID
newE := creds.EffectiveKGID
if e.Ok() {
newE, err = t.creds.UseGID(e)
newE, err = creds.UseGID(e)
if err != nil {
return err
}
}
newS := t.creds.SavedKGID
newS := creds.SavedKGID
if s.Ok() {
newS, err = t.creds.UseGID(s)
newS, err = creds.UseGID(s)
if err != nil {
return err
}
@ -309,9 +315,9 @@ func (t *Task) SetRESGID(r, e, s auth.GID) error {
}
func (t *Task) setKGIDsUncheckedLocked(newR, newE, newS auth.KGID) {
oldE := t.creds.EffectiveKGID
t.creds = t.creds.Fork() // See doc for creds.
t.creds.RealKGID, t.creds.EffectiveKGID, t.creds.SavedKGID = newR, newE, newS
creds := t.Credentials().Fork() // The credentials object is immutable. See doc for creds.
oldE := creds.EffectiveKGID
creds.RealKGID, creds.EffectiveKGID, creds.SavedKGID = newR, newE, newS
if oldE != newE {
// "[dumpability] is reset to the current value contained in
@ -327,6 +333,7 @@ func (t *Task) setKGIDsUncheckedLocked(newR, newE, newS auth.KGID) {
// kernel/cred.c:commit_creds().
t.parentDeathSignal = 0
}
t.creds.Store(creds)
}
// SetExtraGIDs attempts to change t's supplemental groups. All IDs are
@ -334,19 +341,21 @@ func (t *Task) setKGIDsUncheckedLocked(newR, newE, newS auth.KGID) {
func (t *Task) SetExtraGIDs(gids []auth.GID) error {
t.mu.Lock()
defer t.mu.Unlock()
if !t.creds.HasCapability(linux.CAP_SETGID) {
creds := t.Credentials()
if !creds.HasCapability(linux.CAP_SETGID) {
return syserror.EPERM
}
kgids := make([]auth.KGID, len(gids))
for i, gid := range gids {
kgid := t.creds.UserNamespace.MapToKGID(gid)
kgid := creds.UserNamespace.MapToKGID(gid)
if !kgid.Ok() {
return syserror.EINVAL
}
kgids[i] = kgid
}
t.creds = t.creds.Fork() // See doc for creds.
t.creds.ExtraKGIDs = kgids
creds = creds.Fork() // The credentials object is immutable. See doc for creds.
creds.ExtraKGIDs = kgids
t.creds.Store(creds)
return nil
}
@ -360,27 +369,29 @@ func (t *Task) SetCapabilitySets(permitted, inheritable, effective auth.Capabili
if effective & ^permitted != 0 {
return syserror.EPERM
}
creds := t.Credentials()
// "It is also a limiting superset for the capabilities that may be added
// to the inheritable set by a thread that does not have the CAP_SETPCAP
// capability in its effective set."
if !t.creds.HasCapability(linux.CAP_SETPCAP) && (inheritable & ^(t.creds.InheritableCaps|t.creds.PermittedCaps) != 0) {
if !creds.HasCapability(linux.CAP_SETPCAP) && (inheritable & ^(creds.InheritableCaps|creds.PermittedCaps) != 0) {
return syserror.EPERM
}
// "If a thread drops a capability from its permitted set, it can never
// reacquire that capability (unless it execve(2)s ..."
if permitted & ^t.creds.PermittedCaps != 0 {
if permitted & ^creds.PermittedCaps != 0 {
return syserror.EPERM
}
// "... if a capability is not in the bounding set, then a thread can't add
// this capability to its inheritable set, even if it was in its permitted
// capabilities ..."
if inheritable & ^(t.creds.InheritableCaps|t.creds.BoundingCaps) != 0 {
if inheritable & ^(creds.InheritableCaps|creds.BoundingCaps) != 0 {
return syserror.EPERM
}
t.creds = t.creds.Fork() // See doc for creds.
t.creds.PermittedCaps = permitted
t.creds.InheritableCaps = inheritable
t.creds.EffectiveCaps = effective
creds = creds.Fork() // The credentials object is immutable. See doc for creds.
creds.PermittedCaps = permitted
creds.InheritableCaps = inheritable
creds.EffectiveCaps = effective
t.creds.Store(creds)
return nil
}
@ -389,11 +400,13 @@ func (t *Task) SetCapabilitySets(permitted, inheritable, effective auth.Capabili
func (t *Task) DropBoundingCapability(cp linux.Capability) error {
t.mu.Lock()
defer t.mu.Unlock()
if !t.creds.HasCapability(linux.CAP_SETPCAP) {
creds := t.Credentials()
if !creds.HasCapability(linux.CAP_SETPCAP) {
return syserror.EPERM
}
t.creds = t.creds.Fork() // See doc for creds.
t.creds.BoundingCaps &^= auth.CapabilitySetOf(cp)
creds = creds.Fork() // The credentials object is immutable. See doc for creds.
creds.BoundingCaps &^= auth.CapabilitySetOf(cp)
t.creds.Store(creds)
return nil
}
@ -402,31 +415,33 @@ func (t *Task) SetUserNamespace(ns *auth.UserNamespace) error {
t.mu.Lock()
defer t.mu.Unlock()
creds := t.Credentials()
// "A process reassociating itself with a user namespace must have the
// CAP_SYS_ADMIN capability in the target user namespace." - setns(2)
//
// If t just created ns, then t.creds is guaranteed to have CAP_SYS_ADMIN
// in ns (by rule 3 in auth.Credentials.HasCapability).
if !t.creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, ns) {
if !creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, ns) {
return syserror.EPERM
}
t.creds = t.creds.Fork() // See doc for creds.
t.creds.UserNamespace = ns
creds = creds.Fork() // The credentials object is immutable. See doc for creds.
creds.UserNamespace = ns
// "The child process created by clone(2) with the CLONE_NEWUSER flag
// starts out with a complete set of capabilities in the new user
// namespace. Likewise, a process that creates a new user namespace using
// unshare(2) or joins an existing user namespace using setns(2) gains a
// full set of capabilities in that namespace."
t.creds.PermittedCaps = auth.AllCapabilities
t.creds.InheritableCaps = 0
t.creds.EffectiveCaps = auth.AllCapabilities
t.creds.BoundingCaps = auth.AllCapabilities
creds.PermittedCaps = auth.AllCapabilities
creds.InheritableCaps = 0
creds.EffectiveCaps = auth.AllCapabilities
creds.BoundingCaps = auth.AllCapabilities
// "A call to clone(2), unshare(2), or setns(2) using the CLONE_NEWUSER
// flag sets the "securebits" flags (see capabilities(7)) to their default
// values (all flags disabled) in the child (for clone(2)) or caller (for
// unshare(2), or setns(2)." - user_namespaces(7)
t.creds.KeepCaps = false
creds.KeepCaps = false
t.creds.Store(creds)
return nil
}
@ -435,8 +450,9 @@ func (t *Task) SetUserNamespace(ns *auth.UserNamespace) error {
func (t *Task) SetKeepCaps(k bool) {
t.mu.Lock()
defer t.mu.Unlock()
t.creds = t.creds.Fork() // See doc for creds.
t.creds.KeepCaps = k
creds := t.Credentials().Fork() // The credentials object is immutable. See doc for creds.
creds.KeepCaps = k
t.creds.Store(creds)
}
// updateCredsForExec updates t.creds to reflect an execve().
@ -512,15 +528,16 @@ func (t *Task) updateCredsForExecLocked() {
// the effective user ID.
var newPermitted auth.CapabilitySet // since F(inheritable) == F(permitted) == 0
fileEffective := false
root := t.creds.UserNamespace.MapToKUID(auth.RootUID)
if t.creds.EffectiveKUID == root || t.creds.RealKUID == root {
newPermitted = t.creds.InheritableCaps | t.creds.BoundingCaps
if t.creds.EffectiveKUID == root {
creds := t.Credentials()
root := creds.UserNamespace.MapToKUID(auth.RootUID)
if creds.EffectiveKUID == root || creds.RealKUID == root {
newPermitted = creds.InheritableCaps | creds.BoundingCaps
if creds.EffectiveKUID == root {
fileEffective = true
}
}
t.creds = t.creds.Fork() // See doc for creds.
creds = creds.Fork() // The credentials object is immutable. See doc for creds.
// Now we enter poorly-documented, somewhat confusing territory. (The
// accompanying comment in Linux's security/commoncap.c:cap_bprm_set_creds
@ -562,27 +579,28 @@ func (t *Task) updateCredsForExecLocked() {
// But since no_new_privs is always set (A3 is always true), this becomes
// much simpler. If B1 and B2 are false, C2 is a no-op. If B3 is false, C1
// is a no-op. So we can just do C1 and C2 unconditionally.
if t.creds.EffectiveKUID != t.creds.RealKUID || t.creds.EffectiveKGID != t.creds.RealKGID {
t.creds.EffectiveKUID = t.creds.RealKUID
t.creds.EffectiveKGID = t.creds.RealKGID
if creds.EffectiveKUID != creds.RealKUID || creds.EffectiveKGID != creds.RealKGID {
creds.EffectiveKUID = creds.RealKUID
creds.EffectiveKGID = creds.RealKGID
t.parentDeathSignal = 0
}
// (Saved set-user-ID is always set to the new effective user ID, and saved
// set-group-ID is always set to the new effective group ID, regardless of
// the above.)
t.creds.SavedKUID = t.creds.RealKUID
t.creds.SavedKGID = t.creds.RealKGID
t.creds.PermittedCaps &= newPermitted
creds.SavedKUID = creds.RealKUID
creds.SavedKGID = creds.RealKGID
creds.PermittedCaps &= newPermitted
if fileEffective {
t.creds.EffectiveCaps = t.creds.PermittedCaps
creds.EffectiveCaps = creds.PermittedCaps
} else {
t.creds.EffectiveCaps = 0
creds.EffectiveCaps = 0
}
// prctl(2): The "keep capabilities" value will be reset to 0 on subsequent
// calls to execve(2).
t.creds.KeepCaps = false
creds.KeepCaps = false
// "The bounding set is inherited at fork(2) from the thread's parent, and
// is preserved across an execve(2)". So we're done.
t.creds.Store(creds)
}

2
pkg/sentry/kernel/task_start.go
View File

@ -119,7 +119,6 @@ func (ts *TaskSet) newTask(cfg *TaskConfig) (*Task, error) {
ptraceTracees: make(map[*Task]struct{}),
allowedCPUMask: cfg.AllowedCPUMask.Copy(),
ioUsage: &usage.IO{},
creds: cfg.Credentials,
niceness: cfg.Niceness,
netns: cfg.NetworkNamespaced,
utsns: cfg.UTSNamespace,
@ -129,6 +128,7 @@ func (ts *TaskSet) newTask(cfg *TaskConfig) (*Task, error) {
futexWaiter: futex.NewWaiter(),
containerID: cfg.ContainerID,
}
t.creds.Store(cfg.Credentials)
t.endStopCond.L = &t.tg.signalHandlers.mu
t.ptraceTracer.Store((*Task)(nil))
// We don't construct t.blockingTimer until Task.run(); see that function

12
third_party/gvsync/atomicptr_unsafe.go vendored
View File

@ -21,8 +21,18 @@ type Value struct{}
// Note that copying AtomicPtr by value performs a non-atomic read of the
// stored pointer, which is unsafe if Store() can be called concurrently; in
// this case, do `dst.Store(src.Load())` instead.
//
// +stateify savable
type AtomicPtr struct {
ptr unsafe.Pointer
ptr unsafe.Pointer `state:".(*Value)"`
}
func (p *AtomicPtr) savePtr() *Value {
return p.Load()
}
func (p *AtomicPtr) loadPtr(v *Value) {
p.Store(v)
}
// Load returns the value set by the most recent Store. It returns nil if there

6
tools/go_generics/generics.go
View File

@ -222,7 +222,11 @@ func main() {
// Modify the state tag appropriately.
if m := stateTagRegexp.FindStringSubmatch(ident.Name); m != nil {
if t := identifierRegexp.FindStringSubmatch(m[2]); t != nil {
ident.Name = m[1] + `state:".(` + t[1] + *prefix + t[2] + *suffix + t[3] + `)"` + m[3]
typeName := *prefix + t[2] + *suffix
if n, ok := types[t[2]]; ok {
typeName = n
}
ident.Name = m[1] + `state:".(` + t[1] + typeName + t[3] + `)"` + m[3]
}
}
}