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syscall: add CgroupFD support for ForkExec on Linux

Browse Source 
Implement CLONE_INTO_CGROUP feature, allowing to put a child in a
specified cgroup in a clean and simple way. Note that the feature only
works for cgroup v2, and requires Linux kernel 5.7 or newer.

Using the feature requires a new syscall, clone3. Currently this is the
only reason to use clone3, but the code is structured in a way so that
other cases may be easily added in the future.

Add a test case.

While at it, try to simplify the syscall calling code in
forkAndExecInChild1, which became complicated over time because:

1. It was using either rawVforkSyscall or RawSyscall6 depending on
   whether CLONE_NEWUSER was set.

2. On Linux/s390, the first two arguments to clone(2) system call are
   swapped (which deserved a mention in Linux ABI hall of shame). It
   was worked around in rawVforkSyscall on s390, but had to be
   implemented via a switch/case when using RawSyscall6, making the code
   less clear.

Let's

 - modify rawVforkSyscall to have two arguments (which is also required
   for clone3);

 - remove the arguments workaround from s390 asm, instead implementing
   arguments swap in the caller (which still looks ugly but at least
   it's done once and is clearly documented now);

 - use rawVforkSyscall for all cases (since it is essentially similar to
   RawSyscall6, except for having less parameters, not returning r2, and
   saving/restoring the return address before/after syscall on 386 and
   amd64).

Updates #51246.

Change-Id: Ifcd418ebead9257177338ffbcccd0bdecb94474e
Reviewed-on: https://go-review.googlesource.com/c/go/+/417695
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Kirill Kolyshkin <kolyshkin@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Kir Kolyshkin 2022-07-14 21:18:15 -07:00 committed by Gopher Robot
parent f53b2111e4
commit bca17d16ca
24 changed files with 228 additions and 99 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
api/next/51246.txt
View File

@ -8,6 +8,8 @@ pkg syscall (linux-386), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-386), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-386), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-386), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-386), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-386), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-386-cgo), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-386-cgo), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-386-cgo), const CLONE_INTO_CGROUP = 8589934592 #51246
@ -18,6 +20,8 @@ pkg syscall (linux-386-cgo), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-386-cgo), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-386-cgo), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-386-cgo), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-386-cgo), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-386-cgo), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-amd64), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-amd64), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-amd64), const CLONE_INTO_CGROUP = 8589934592 #51246
@ -28,6 +32,8 @@ pkg syscall (linux-amd64), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-amd64), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-amd64), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-amd64), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-amd64), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-amd64), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-amd64-cgo), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-amd64-cgo), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-amd64-cgo), const CLONE_INTO_CGROUP = 8589934592 #51246
@ -38,6 +44,8 @@ pkg syscall (linux-amd64-cgo), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-amd64-cgo), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-amd64-cgo), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-amd64-cgo), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-amd64-cgo), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-amd64-cgo), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-arm), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-arm), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-arm), const CLONE_INTO_CGROUP = 8589934592 #51246
@ -48,6 +56,8 @@ pkg syscall (linux-arm), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-arm), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-arm), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-arm), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-arm), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-arm), type SysProcAttr struct, UseCgroupFD bool #51246
pkg syscall (linux-arm-cgo), const CLONE_CLEAR_SIGHAND = 4294967296 #51246
pkg syscall (linux-arm-cgo), const CLONE_CLEAR_SIGHAND ideal-int #51246
pkg syscall (linux-arm-cgo), const CLONE_INTO_CGROUP = 8589934592 #51246
@ -58,3 +68,5 @@ pkg syscall (linux-arm-cgo), const CLONE_NEWTIME = 128 #51246
pkg syscall (linux-arm-cgo), const CLONE_NEWTIME ideal-int #51246
pkg syscall (linux-arm-cgo), const CLONE_PIDFD = 4096 #51246
pkg syscall (linux-arm-cgo), const CLONE_PIDFD ideal-int #51246
pkg syscall (linux-arm-cgo), type SysProcAttr struct, CgroupFD int #51246
pkg syscall (linux-arm-cgo), type SysProcAttr struct, UseCgroupFD bool #51246

14
src/syscall/asm_linux_386.s
View File

@ -13,24 +13,24 @@
// instead of the glibc-specific "CALL 0x10(GS)".
#define INVOKE_SYSCALL INT $0x80
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-16
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-20
MOVL trap+0(FP), AX // syscall entry
MOVL a1+4(FP), BX
MOVL $0, CX
MOVL a2+8(FP), CX
MOVL $0, DX
POPL SI // preserve return address
INVOKE_SYSCALL
PUSHL SI
CMPL AX, $0xfffff001
JLS ok
MOVL $-1, r1+8(FP)
MOVL $-1, r1+12(FP)
NEGL AX
MOVL AX, err+12(FP)
MOVL AX, err+16(FP)
RET
ok:
MOVL AX, r1+8(FP)
MOVL $0, err+12(FP)
MOVL AX, r1+12(FP)
MOVL $0, err+16(FP)
RET
// func rawSyscallNoError(trap uintptr, a1, a2, a3 uintptr) (r1, r2 uintptr);

14
src/syscall/asm_linux_amd64.s
View File

@ -11,10 +11,10 @@
#define SYS_gettimeofday 96
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-40
MOVQ a1+8(FP), DI
MOVQ $0, SI
MOVQ a2+16(FP), SI
MOVQ $0, DX
MOVQ $0, R10
MOVQ $0, R8
@ -25,13 +25,13 @@ TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
PUSHQ R12
CMPQ AX, $0xfffffffffffff001
JLS ok2
MOVQ $-1, r1+16(FP)
MOVQ $-1, r1+24(FP)
NEGQ AX
MOVQ AX, err+24(FP)
MOVQ AX, err+32(FP)
RET
ok2:
MOVQ AX, r1+16(FP)
MOVQ $0, err+24(FP)
MOVQ AX, r1+24(FP)
MOVQ $0, err+32(FP)
RET
// func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)

14
src/syscall/asm_linux_arm.s
View File

@ -41,25 +41,25 @@ okseek:
BL runtime·exitsyscall(SB)
RET
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-16
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-20
MOVW trap+0(FP), R7 // syscall entry
MOVW a1+4(FP), R0
MOVW $0, R1
MOVW a2+8(FP), R1
MOVW $0, R2
SWI $0
MOVW $0xfffff001, R1
CMP R1, R0
BLS ok
MOVW $-1, R1
MOVW R1, r1+8(FP)
MOVW R1, r1+12(FP)
RSB $0, R0, R0
MOVW R0, err+12(FP)
MOVW R0, err+16(FP)
RET
ok:
MOVW R0, r1+8(FP)
MOVW R0, r1+12(FP)
MOVW $0, R0
MOVW R0, err+12(FP)
MOVW R0, err+16(FP)
RET
// func rawSyscallNoError(trap uintptr, a1, a2, a3 uintptr) (r1, r2 uintptr);

14
src/syscall/asm_linux_arm64.s
View File

@ -4,10 +4,10 @@
#include "textflag.h"
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT,$0-32
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT,$0-40
MOVD a1+8(FP), R0
MOVD $0, R1
MOVD a2+16(FP), R1
MOVD $0, R2
MOVD $0, R3
MOVD $0, R4
@ -17,13 +17,13 @@ TEXT ·rawVforkSyscall(SB),NOSPLIT,$0-32
CMN $4095, R0
BCC ok
MOVD $-1, R4
MOVD R4, r1+16(FP) // r1
MOVD R4, r1+24(FP) // r1
NEG R0, R0
MOVD R0, err+24(FP) // errno
MOVD R0, err+32(FP) // errno
RET
ok:
MOVD R0, r1+16(FP) // r1
MOVD ZR, err+24(FP) // errno
MOVD R0, r1+24(FP) // r1
MOVD ZR, err+32(FP) // errno
RET
// func rawSyscallNoError(trap uintptr, a1, a2, a3 uintptr) (r1, r2 uintptr);

14
src/syscall/asm_linux_loong64.s
View File

@ -8,10 +8,10 @@
// System calls for loong64, Linux
//
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT,$0-32
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT,$0-40
MOVV a1+8(FP), R4
MOVV $0, R5
MOVV a2+16(FP), R5
MOVV $0, R6
MOVV $0, R7
MOVV $0, R8
@ -21,13 +21,13 @@ TEXT ·rawVforkSyscall(SB),NOSPLIT,$0-32
MOVW $-4096, R12
BGEU R12, R4, ok
MOVV $-1, R12
MOVV R12, r1+16(FP) // r1
MOVV R12, r1+24(FP) // r1
SUBVU R4, R0, R4
MOVV R4, err+24(FP) // errno
MOVV R4, err+32(FP) // errno
RET
ok:
MOVV R4, r1+16(FP) // r1
MOVV R0, err+24(FP) // errno
MOVV R4, r1+24(FP) // r1
MOVV R0, err+32(FP) // errno
RET
TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48

14
src/syscall/asm_linux_mips64x.s
View File

@ -10,10 +10,10 @@
// System calls for mips64, Linux
//
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-40
MOVV a1+8(FP), R4
MOVV R0, R5
MOVV a2+16(FP), R5
MOVV R0, R6
MOVV R0, R7
MOVV R0, R8
@ -22,12 +22,12 @@ TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
SYSCALL
BEQ R7, ok
MOVV $-1, R1
MOVV R1, r1+16(FP) // r1
MOVV R2, err+24(FP) // errno
MOVV R1, r1+24(FP) // r1
MOVV R2, err+32(FP) // errno
RET
ok:
MOVV R2, r1+16(FP) // r1
MOVV R0, err+24(FP) // errno
MOVV R2, r1+24(FP) // r1
MOVV R0, err+32(FP) // errno
RET
TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48

14
src/syscall/asm_linux_mipsx.s
View File

@ -44,21 +44,21 @@ ok9:
JAL runtime·exitsyscall(SB)
RET
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-16
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-20
MOVW a1+4(FP), R4
MOVW R0, R5
MOVW a2+8(FP), R5
MOVW R0, R6
MOVW trap+0(FP), R2 // syscall entry
SYSCALL
BEQ R7, ok
MOVW $-1, R1
MOVW R1, r1+8(FP) // r1
MOVW R2, err+12(FP) // errno
MOVW R1, r1+12(FP) // r1
MOVW R2, err+16(FP) // errno
RET
ok:
MOVW R2, r1+8(FP) // r1
MOVW R0, err+12(FP) // errno
MOVW R2, r1+12(FP) // r1
MOVW R0, err+16(FP) // errno
RET
TEXT ·rawSyscallNoError(SB),NOSPLIT,$20-24

14
src/syscall/asm_linux_ppc64x.s
View File

@ -10,10 +10,10 @@
// System calls for ppc64, Linux
//
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-40
MOVD a1+8(FP), R3
MOVD R0, R4
MOVD a2+16(FP), R4
MOVD R0, R5
MOVD R0, R6
MOVD R0, R7
@ -22,12 +22,12 @@ TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
SYSCALL R9
BVC ok
MOVD $-1, R4
MOVD R4, r1+16(FP) // r1
MOVD R3, err+24(FP) // errno
MOVD R4, r1+24(FP) // r1
MOVD R3, err+32(FP) // errno
RET
ok:
MOVD R3, r1+16(FP) // r1
MOVD R0, err+24(FP) // errno
MOVD R3, r1+24(FP) // r1
MOVD R0, err+32(FP) // errno
RET
TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48

14
src/syscall/asm_linux_riscv64.s
View File

@ -8,10 +8,10 @@
// System calls for riscv64, Linux
//
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-40
MOV a1+8(FP), A0
MOV ZERO, A1
MOV a2+16(FP), A1
MOV ZERO, A2
MOV ZERO, A3
MOV ZERO, A4
@ -20,14 +20,14 @@ TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
ECALL
MOV $-4096, T0
BLTU T0, A0, err
MOV A0, r1+16(FP) // r1
MOV ZERO, err+24(FP) // errno
MOV A0, r1+24(FP) // r1
MOV ZERO, err+32(FP) // errno
RET
err:
MOV $-1, T0
MOV T0, r1+16(FP) // r1
MOV T0, r1+24(FP) // r1
SUB A0, ZERO, A0
MOV A0, err+24(FP) // errno
MOV A0, err+32(FP) // errno
RET
TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48

16
src/syscall/asm_linux_s390x.s
View File

@ -8,10 +8,10 @@
// System calls for s390x, Linux
//
// func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
MOVD $0, R2
MOVD a1+8(FP), R3
// func rawVforkSyscall(trap, a1, a2 uintptr) (r1, err uintptr)
TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-40
MOVD a1+8(FP), R2
MOVD a2+16(FP), R3
MOVD $0, R4
MOVD $0, R5
MOVD $0, R6
@ -20,13 +20,13 @@ TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
SYSCALL
MOVD $0xfffffffffffff001, R8
CMPUBLT R2, R8, ok2
MOVD $-1, r1+16(FP)
MOVD $-1, r1+24(FP)
NEG R2, R2
MOVD R2, err+24(FP) // errno
MOVD R2, err+32(FP) // errno
RET
ok2:
MOVD R2, r1+16(FP)
MOVD $0, err+24(FP) // errno
MOVD R2, r1+24(FP)
MOVD $0, err+32(FP) // errno
RET
// func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)

50
src/syscall/exec_linux.go
View File

@ -99,6 +99,8 @@ type SysProcAttr struct {
// users this should be set to false for mappings work.
GidMappingsEnableSetgroups bool
AmbientCaps []uintptr // Ambient capabilities (Linux only)
UseCgroupFD bool // Whether to make use of the CgroupFD field.
CgroupFD int // File descriptor of a cgroup to put the new process into.
}
var (
@ -176,6 +178,21 @@ func capToIndex(cap uintptr) uintptr { return cap >> 5 }
// See CAP_TO_MASK in linux/capability.h:
func capToMask(cap uintptr) uint32 { return 1 << uint(cap&31) }
// cloneArgs holds arguments for clone3 Linux syscall.
type cloneArgs struct {
flags uint64 // Flags bit mask
pidFD uint64 // Where to store PID file descriptor (int *)
childTID uint64 // Where to store child TID, in child's memory (pid_t *)
parentTID uint64 // Where to store child TID, in parent's memory (pid_t *)
exitSignal uint64 // Signal to deliver to parent on child termination
stack uint64 // Pointer to lowest byte of stack
stackSize uint64 // Size of stack
tls uint64 // Location of new TLS
setTID uint64 // Pointer to a pid_t array (since Linux 5.5)
setTIDSize uint64 // Number of elements in set_tid (since Linux 5.5)
cgroup uint64 // File descriptor for target cgroup of child (since Linux 5.7)
}
// forkAndExecInChild1 implements the body of forkAndExecInChild up to
// the parent's post-fork path. This is a separate function so we can
// separate the child's and parent's stack frames if we're using
@ -205,9 +222,10 @@ func forkAndExecInChild1(argv0 *byte, argv, envv []*byte, chroot, dir *byte, att
nextfd int
i int
caps caps
fd1 uintptr
fd1, flags uintptr
puid, psetgroups, pgid []byte
uidmap, setgroups, gidmap []byte
clone3 *cloneArgs
)
if sys.UidMappings != nil {
@ -252,17 +270,33 @@ func forkAndExecInChild1(argv0 *byte, argv, envv []*byte, chroot, dir *byte, att
}
}
flags = sys.Cloneflags
if sys.Cloneflags&CLONE_NEWUSER == 0 && sys.Unshareflags&CLONE_NEWUSER == 0 {
flags |= CLONE_VFORK | CLONE_VM
}
// Whether to use clone3.
if sys.UseCgroupFD {
clone3 = &cloneArgs{
flags: uint64(flags) | CLONE_INTO_CGROUP,
exitSignal: uint64(SIGCHLD),
cgroup: uint64(sys.CgroupFD),
}
}
// About to call fork.
// No more allocation or calls of non-assembly functions.
runtime_BeforeFork()
locked = true
switch {
case sys.Cloneflags&CLONE_NEWUSER == 0 && sys.Unshareflags&CLONE_NEWUSER == 0:
r1, err1 = rawVforkSyscall(SYS_CLONE, uintptr(SIGCHLD|CLONE_VFORK|CLONE_VM)|sys.Cloneflags)
case runtime.GOARCH == "s390x":
r1, _, err1 = RawSyscall6(SYS_CLONE, 0, uintptr(SIGCHLD)|sys.Cloneflags, 0, 0, 0, 0)
default:
r1, _, err1 = RawSyscall6(SYS_CLONE, uintptr(SIGCHLD)|sys.Cloneflags, 0, 0, 0, 0, 0)
if clone3 != nil {
r1, err1 = rawVforkSyscall(_SYS_clone3, uintptr(unsafe.Pointer(clone3)), unsafe.Sizeof(*clone3))
} else {
flags |= uintptr(SIGCHLD)
if runtime.GOARCH == "s390x" {
// On Linux/s390, the first two arguments of clone(2) are swapped.
r1, err1 = rawVforkSyscall(SYS_CLONE, 0, flags)
} else {
r1, err1 = rawVforkSyscall(SYS_CLONE, flags, 0)
}
}
if err1 != 0 || r1 != 0 {
// If we're in the parent, we must return immediately

92
src/syscall/exec_linux_test.go
View File

@ -7,6 +7,7 @@
package syscall_test
import (
"bytes"
"flag"
"fmt"
"internal/testenv"
@ -14,6 +15,7 @@ import (
"os"
"os/exec"
"os/user"
"path"
"path/filepath"
"runtime"
"strconv"
@ -461,6 +463,96 @@ func TestUnshareUidGidMapping(t *testing.T) {
}
}
func prepareCgroupFD(t *testing.T) (int, string) {
t.Helper()
const O_PATH = 0x200000 // Same for all architectures, but for some reason not defined in syscall for 386||amd64.
// Requires cgroup v2.
const prefix = "/sys/fs/cgroup"
selfCg, err := os.ReadFile("/proc/self/cgroup")
if err != nil {
if os.IsNotExist(err) || os.IsPermission(err) {
t.Skip(err)
}
t.Fatal(err)
}
// Expect a single line like this:
// 0::/user.slice/user-1000.slice/user@1000.service/app.slice/vte-spawn-891992a2-efbb-4f28-aedb-b24f9e706770.scope
// Otherwise it's either cgroup v1 or a hybrid hierarchy.
if bytes.Count(selfCg, []byte("\n")) > 1 {
t.Skip("cgroup v2 not available")
}
cg := bytes.TrimPrefix(selfCg, []byte("0::"))
if len(cg) == len(selfCg) { // No prefix found.
t.Skipf("cgroup v2 not available (/proc/self/cgroup contents: %q)", selfCg)
}
// Need clone3 with CLONE_INTO_CGROUP support.
_, err = syscall.ForkExec("non-existent binary", nil, &syscall.ProcAttr{
Sys: &syscall.SysProcAttr{
UseCgroupFD: true,
CgroupFD: -1,
},
})
// // EPERM can be returned if clone3 is not enabled by seccomp.
if err == syscall.ENOSYS || err == syscall.EPERM {
t.Skipf("clone3 with CLONE_INTO_CGROUP not available: %v", err)
}
// Need an ability to create a sub-cgroup.
subCgroup, err := os.MkdirTemp(prefix+string(bytes.TrimSpace(cg)), "subcg-")
if err != nil {
if os.IsPermission(err) {
t.Skip(err)
}
t.Fatal(err)
}
t.Cleanup(func() { syscall.Rmdir(subCgroup) })
cgroupFD, err := syscall.Open(subCgroup, O_PATH, 0)
if err != nil {
t.Fatal(&os.PathError{Op: "open", Path: subCgroup, Err: err})
}
t.Cleanup(func() { syscall.Close(cgroupFD) })
return cgroupFD, "/" + path.Base(subCgroup)
}
func TestUseCgroupFD(t *testing.T) {
fd, suffix := prepareCgroupFD(t)
cmd := exec.Command(os.Args[0], "-test.run=TestUseCgroupFDHelper")
cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
cmd.SysProcAttr = &syscall.SysProcAttr{
UseCgroupFD: true,
CgroupFD: fd,
}
out, err := cmd.CombinedOutput()
if err != nil {
t.Fatalf("Cmd failed with err %v, output: %s", err, out)
}
// NB: this wouldn't work with cgroupns.
if !bytes.HasSuffix(bytes.TrimSpace(out), []byte(suffix)) {
t.Fatalf("got: %q, want: a line that ends with %q", out, suffix)
}
}
func TestUseCgroupFDHelper(*testing.T) {
if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
return
}
defer os.Exit(0)
// Read and print own cgroup path.
selfCg, err := os.ReadFile("/proc/self/cgroup")
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(2)
}
fmt.Print(string(selfCg))
}
type capHeader struct {
version uint32
pid int32

1
src/syscall/syscall_linux.go
View File

@ -94,6 +94,7 @@ func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
}
func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)
func rawVforkSyscall(trap, a1, a2 uintptr) (r1 uintptr, err Errno)
/*
* Wrapped

3
src/syscall/syscall_linux_386.go
View File

@ -8,6 +8,7 @@ import "unsafe"
const (
_SYS_setgroups = SYS_SETGROUPS32
_SYS_clone3 = 435
_SYS_faccessat2 = 439
)
@ -348,5 +349,3 @@ func (msghdr *Msghdr) SetControllen(length int) {
func (cmsg *Cmsghdr) SetLen(length int) {
cmsg.Len = uint32(length)
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)

3
src/syscall/syscall_linux_amd64.go
View File

@ -6,6 +6,7 @@ package syscall
const (
_SYS_setgroups = SYS_SETGROUPS
_SYS_clone3 = 435
_SYS_faccessat2 = 439
)
@ -120,5 +121,3 @@ func (msghdr *Msghdr) SetControllen(length int) {
func (cmsg *Cmsghdr) SetLen(length int) {
cmsg.Len = uint64(length)
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)

3
src/syscall/syscall_linux_arm.go
View File

@ -8,6 +8,7 @@ import "unsafe"
const (
_SYS_setgroups = SYS_SETGROUPS32
_SYS_clone3 = 435
_SYS_faccessat2 = 439
)
@ -200,5 +201,3 @@ func (msghdr *Msghdr) SetControllen(length int) {
func (cmsg *Cmsghdr) SetLen(length int) {
cmsg.Len = uint32(length)
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)

3
src/syscall/syscall_linux_arm64.go
View File

@ -8,6 +8,7 @@ import "unsafe"
const (
_SYS_setgroups = SYS_SETGROUPS
_SYS_clone3 = 435
_SYS_faccessat2 = 439
)
@ -182,5 +183,3 @@ func Pause() error {
_, err := ppoll(nil, 0, nil, nil)
return err
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)

3
src/syscall/syscall_linux_loong64.go
View File

@ -8,6 +8,7 @@ import "unsafe"
const (
_SYS_setgroups = SYS_SETGROUPS
_SYS_clone3 = 435
_SYS_faccessat2 = 439
)
@ -217,5 +218,3 @@ func Pause() error {
_, err := ppoll(nil, 0, nil, nil)
return err
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)

3
src/syscall/syscall_linux_mips64x.go
View File

@ -8,6 +8,7 @@ package syscall
const (
_SYS_setgroups = SYS_SETGROUPS
_SYS_clone3 = 5435
_SYS_faccessat2 = 5439
)
@ -182,5 +183,3 @@ func (msghdr *Msghdr) SetControllen(length int) {
func (cmsg *Cmsghdr) SetLen(length int) {
cmsg.Len = uint64(length)
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)

3
src/syscall/syscall_linux_mipsx.go
View File

@ -10,6 +10,7 @@ import "unsafe"
const (
_SYS_setgroups = SYS_SETGROUPS
_SYS_clone3 = 4435
_SYS_faccessat2 = 4439
)
@ -193,5 +194,3 @@ func (msghdr *Msghdr) SetControllen(length int) {
func (cmsg *Cmsghdr) SetLen(length int) {
cmsg.Len = uint32(length)
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)

3
src/syscall/syscall_linux_ppc64x.go
View File

@ -8,6 +8,7 @@ package syscall
const (
_SYS_setgroups = SYS_SETGROUPS
_SYS_clone3 = 435
_SYS_faccessat2 = 439
)
@ -91,8 +92,6 @@ func (cmsg *Cmsghdr) SetLen(length int) {
cmsg.Len = uint64(length)
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)
//sys syncFileRange2(fd int, flags int, off int64, n int64) (err error) = SYS_SYNC_FILE_RANGE2
func SyncFileRange(fd int, off int64, n int64, flags int) error {

3
src/syscall/syscall_linux_riscv64.go
View File

@ -8,6 +8,7 @@ import "unsafe"
const (
_SYS_setgroups = SYS_SETGROUPS
_SYS_clone3 = 435
_SYS_faccessat2 = 439
)
@ -168,5 +169,3 @@ func Pause() error {
_, err := ppoll(nil, 0, nil, nil)
return err
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)

3
src/syscall/syscall_linux_s390x.go
View File

@ -8,6 +8,7 @@ import "unsafe"
const (
_SYS_setgroups = SYS_SETGROUPS
_SYS_clone3 = 435
_SYS_faccessat2 = 439
)
@ -257,5 +258,3 @@ func (msghdr *Msghdr) SetControllen(length int) {
func (cmsg *Cmsghdr) SetLen(length int) {
cmsg.Len = uint64(length)
}
func rawVforkSyscall(trap, a1 uintptr) (r1 uintptr, err Errno)