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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package linux
import (
"fmt"
"syscall"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/mm"
)
// Prctl implements linux syscall prctl(2).
// It has a list of subfunctions which operate on the process. The arguments are
// all based on each subfunction.
func Prctl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
option := args[0].Int()
switch option {
case linux.PR_SET_PDEATHSIG:
sig := linux.Signal(args[1].Int())
if sig != 0 && !sig.IsValid() {
return 0, nil, syscall.EINVAL
}
t.SetParentDeathSignal(sig)
return 0, nil, nil
case linux.PR_GET_PDEATHSIG:
_, err := t.CopyOut(args[1].Pointer(), int32(t.ParentDeathSignal()))
return 0, nil, err
case linux.PR_GET_DUMPABLE:
d := t.MemoryManager().Dumpability()
switch d {
case mm.NotDumpable:
return linux.SUID_DUMP_DISABLE, nil, nil
case mm.UserDumpable:
return linux.SUID_DUMP_USER, nil, nil
case mm.RootDumpable:
return linux.SUID_DUMP_ROOT, nil, nil
default:
panic(fmt.Sprintf("Unknown dumpability %v", d))
}
case linux.PR_SET_DUMPABLE:
var d mm.Dumpability
switch args[1].Int() {
case linux.SUID_DUMP_DISABLE:
d = mm.NotDumpable
case linux.SUID_DUMP_USER:
d = mm.UserDumpable
default:
// N.B. Userspace may not pass SUID_DUMP_ROOT.
return 0, nil, syscall.EINVAL
}
t.MemoryManager().SetDumpability(d)
return 0, nil, nil
case linux.PR_GET_KEEPCAPS:
if t.Credentials().KeepCaps {
return 1, nil, nil
}
return 0, nil, nil
case linux.PR_SET_KEEPCAPS:
val := args[1].Int()
// prctl(2): arg2 must be either 0 (permitted capabilities are cleared)
// or 1 (permitted capabilities are kept).
if val == 0 {
t.SetKeepCaps(false)
} else if val == 1 {
t.SetKeepCaps(true)
} else {
return 0, nil, syscall.EINVAL
}
return 0, nil, nil
case linux.PR_SET_NAME:
addr := args[1].Pointer()
name, err := t.CopyInString(addr, linux.TASK_COMM_LEN-1)
if err != nil && err != syscall.ENAMETOOLONG {
return 0, nil, err
}
t.SetName(name)
case linux.PR_GET_NAME:
addr := args[1].Pointer()
buf := t.CopyScratchBuffer(linux.TASK_COMM_LEN)
len := copy(buf, t.Name())
if len < linux.TASK_COMM_LEN {
buf[len] = 0
len++
}
_, err := t.CopyOut(addr, buf[:len])
if err != nil {
return 0, nil, err
}
case linux.PR_SET_MM:
if !t.HasCapability(linux.CAP_SYS_RESOURCE) {
return 0, nil, syscall.EPERM
}
switch args[1].Int() {
case linux.PR_SET_MM_EXE_FILE:
fd := args[2].Int()
file := t.GetFile(fd)
if file == nil {
return 0, nil, syscall.EBADF
}
defer file.DecRef()
// They trying to set exe to a non-file?
if !fs.IsFile(file.Dirent.Inode.StableAttr) {
return 0, nil, syscall.EBADF
}
// Set the underlying executable.
t.MemoryManager().SetExecutable(file.Dirent)
case linux.PR_SET_MM_AUXV,
linux.PR_SET_MM_START_CODE,
linux.PR_SET_MM_END_CODE,
linux.PR_SET_MM_START_DATA,
linux.PR_SET_MM_END_DATA,
linux.PR_SET_MM_START_STACK,
linux.PR_SET_MM_START_BRK,
linux.PR_SET_MM_BRK,
linux.PR_SET_MM_ARG_START,
linux.PR_SET_MM_ARG_END,
linux.PR_SET_MM_ENV_START,
linux.PR_SET_MM_ENV_END:
t.Kernel().EmitUnimplementedEvent(t)
fallthrough
default:
return 0, nil, syscall.EINVAL
}
case linux.PR_SET_NO_NEW_PRIVS:
if args[1].Int() != 1 || args[2].Int() != 0 || args[3].Int() != 0 || args[4].Int() != 0 {
return 0, nil, syscall.EINVAL
}
// no_new_privs is assumed to always be set. See
// kernel.Task.updateCredsForExec.
return 0, nil, nil
case linux.PR_GET_NO_NEW_PRIVS:
if args[1].Int() != 0 || args[2].Int() != 0 || args[3].Int() != 0 || args[4].Int() != 0 {
return 0, nil, syscall.EINVAL
}
return 1, nil, nil
case linux.PR_SET_SECCOMP:
if args[1].Int() != linux.SECCOMP_MODE_FILTER {
// Unsupported mode.
return 0, nil, syscall.EINVAL
}
return 0, nil, seccomp(t, linux.SECCOMP_SET_MODE_FILTER, 0, args[2].Pointer())
case linux.PR_GET_SECCOMP:
return uintptr(t.SeccompMode()), nil, nil
case linux.PR_CAPBSET_READ:
cp := linux.Capability(args[1].Uint64())
if !cp.Ok() {
return 0, nil, syscall.EINVAL
}
var rv uintptr
if auth.CapabilitySetOf(cp)&t.Credentials().BoundingCaps != 0 {
rv = 1
}
return rv, nil, nil
case linux.PR_CAPBSET_DROP:
cp := linux.Capability(args[1].Uint64())
if !cp.Ok() {
return 0, nil, syscall.EINVAL
}
return 0, nil, t.DropBoundingCapability(cp)
case linux.PR_GET_TIMING,
linux.PR_SET_TIMING,
linux.PR_GET_TSC,
linux.PR_SET_TSC,
linux.PR_TASK_PERF_EVENTS_DISABLE,
linux.PR_TASK_PERF_EVENTS_ENABLE,
linux.PR_GET_TIMERSLACK,
linux.PR_SET_TIMERSLACK,
linux.PR_MCE_KILL,
linux.PR_MCE_KILL_GET,
linux.PR_GET_TID_ADDRESS,
linux.PR_SET_CHILD_SUBREAPER,
linux.PR_GET_CHILD_SUBREAPER,
linux.PR_GET_THP_DISABLE,
linux.PR_SET_THP_DISABLE,
linux.PR_MPX_ENABLE_MANAGEMENT,
linux.PR_MPX_DISABLE_MANAGEMENT:
t.Kernel().EmitUnimplementedEvent(t)
fallthrough
default:
return 0, nil, syscall.EINVAL
}
return 0, nil, nil
}
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