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unix: use libc stubs for OpenBSD pledge+unveil
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Future OpenBSD releases will remove the syscall(2) interface.
This converts the Pledge and Unveil calls to use pledge(2) and
unveil(2) from libc, rather than indirectly through syscall(2).

Updates golang/go#63900.

Change-Id: I61e22d8f52f16c8f5e4c0717acae0d5bf4271503
GitHub-Last-Rev: ebc0461
GitHub-Pull-Request: #146
Reviewed-on: https://go-review.googlesource.com/c/sys/+/468095
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Aaron Bieber <aaron@bolddaemon.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
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jrick authored and 4a6f656c committed Nov 3, 2023
1 parent 1168e25 commit 661d749
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Showing 17 changed files with 296 additions and 52 deletions.
40 changes: 7 additions & 33 deletions unix/pledge_openbsd.go
Original file line number Diff line number Diff line change
Expand Up @@ -8,8 +8,6 @@ import (
"errors"
"fmt"
"strconv"
"syscall"
"unsafe"
)

// Pledge implements the pledge syscall.
Expand All @@ -24,23 +22,17 @@ func Pledge(promises, execpromises string) error {
return err
}

pptr, err := syscall.BytePtrFromString(promises)
pptr, err := BytePtrFromString(promises)
if err != nil {
return err
}

exptr, err := syscall.BytePtrFromString(execpromises)
exptr, err := BytePtrFromString(execpromises)
if err != nil {
return err
}

_, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(unsafe.Pointer(pptr)),
uintptr(unsafe.Pointer(exptr)), 0)
if e != 0 {
return e
}

return nil
return pledge(pptr, exptr)
}

// PledgePromises implements the pledge syscall.
Expand All @@ -53,21 +45,12 @@ func PledgePromises(promises string) error {
return err
}

// This variable holds the execpromises and is always nil.
var expr unsafe.Pointer

pptr, err := syscall.BytePtrFromString(promises)
pptr, err := BytePtrFromString(promises)
if err != nil {
return err
}

_, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(unsafe.Pointer(pptr)),
uintptr(expr), 0)
if e != 0 {
return e
}

return nil
return pledge(pptr, nil)
}

// PledgeExecpromises implements the pledge syscall.
Expand All @@ -80,21 +63,12 @@ func PledgeExecpromises(execpromises string) error {
return err
}

// This variable holds the promises and is always nil.
var pptr unsafe.Pointer

exptr, err := syscall.BytePtrFromString(execpromises)
exptr, err := BytePtrFromString(execpromises)
if err != nil {
return err
}

_, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(pptr),
uintptr(unsafe.Pointer(exptr)), 0)
if e != 0 {
return e
}

return nil
return pledge(nil, exptr)
}

// majmin returns major and minor version number for an OpenBSD system.
Expand Down
2 changes: 2 additions & 0 deletions unix/syscall_openbsd.go
Original file line number Diff line number Diff line change
Expand Up @@ -327,3 +327,5 @@ func Uname(uname *Utsname) error {
//sys mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
//sys munmap(addr uintptr, length uintptr) (err error)
//sys utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error)
//sys pledge(promises *byte, execpromises *byte) (err error)
//sys unveil(path *byte, flags *byte) (err error)
24 changes: 5 additions & 19 deletions unix/unveil_openbsd.go
Original file line number Diff line number Diff line change
Expand Up @@ -4,11 +4,7 @@

package unix

import (
"fmt"
"syscall"
"unsafe"
)
import "fmt"

// Unveil implements the unveil syscall.
// For more information see unveil(2).
Expand All @@ -18,19 +14,15 @@ func Unveil(path string, flags string) error {
if err := supportsUnveil(); err != nil {
return err
}
pathPtr, err := syscall.BytePtrFromString(path)
pathPtr, err := BytePtrFromString(path)
if err != nil {
return err
}
flagsPtr, err := syscall.BytePtrFromString(flags)
flagsPtr, err := BytePtrFromString(flags)
if err != nil {
return err
}
_, _, e := syscall.Syscall(SYS_UNVEIL, uintptr(unsafe.Pointer(pathPtr)), uintptr(unsafe.Pointer(flagsPtr)), 0)
if e != 0 {
return e
}
return nil
return unveil(pathPtr, flagsPtr)
}

// UnveilBlock blocks future unveil calls.
Expand All @@ -39,13 +31,7 @@ func UnveilBlock() error {
if err := supportsUnveil(); err != nil {
return err
}
// Both pointers must be nil.
var pathUnsafe, flagsUnsafe unsafe.Pointer
_, _, e := syscall.Syscall(SYS_UNVEIL, uintptr(pathUnsafe), uintptr(flagsUnsafe), 0)
if e != 0 {
return e
}
return nil
return unveil(nil, nil)
}

// supportsUnveil checks for availability of the unveil(2) system call based
Expand Down
30 changes: 30 additions & 0 deletions unix/zsyscall_openbsd_386.go

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10 changes: 10 additions & 0 deletions unix/zsyscall_openbsd_386.s
Original file line number Diff line number Diff line change
Expand Up @@ -672,3 +672,13 @@ TEXT libc_utimensat_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_utimensat(SB)
GLOBL ·libc_utimensat_trampoline_addr(SB), RODATA, $4
DATA ·libc_utimensat_trampoline_addr(SB)/4, $libc_utimensat_trampoline<>(SB)

TEXT libc_pledge_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_pledge(SB)
GLOBL ·libc_pledge_trampoline_addr(SB), RODATA, $4
DATA ·libc_pledge_trampoline_addr(SB)/4, $libc_pledge_trampoline<>(SB)

TEXT libc_unveil_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_unveil(SB)
GLOBL ·libc_unveil_trampoline_addr(SB), RODATA, $4
DATA ·libc_unveil_trampoline_addr(SB)/4, $libc_unveil_trampoline<>(SB)
30 changes: 30 additions & 0 deletions unix/zsyscall_openbsd_amd64.go

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10 changes: 10 additions & 0 deletions unix/zsyscall_openbsd_amd64.s
Original file line number Diff line number Diff line change
Expand Up @@ -672,3 +672,13 @@ TEXT libc_utimensat_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_utimensat(SB)
GLOBL ·libc_utimensat_trampoline_addr(SB), RODATA, $8
DATA ·libc_utimensat_trampoline_addr(SB)/8, $libc_utimensat_trampoline<>(SB)

TEXT libc_pledge_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_pledge(SB)
GLOBL ·libc_pledge_trampoline_addr(SB), RODATA, $8
DATA ·libc_pledge_trampoline_addr(SB)/8, $libc_pledge_trampoline<>(SB)

TEXT libc_unveil_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_unveil(SB)
GLOBL ·libc_unveil_trampoline_addr(SB), RODATA, $8
DATA ·libc_unveil_trampoline_addr(SB)/8, $libc_unveil_trampoline<>(SB)
30 changes: 30 additions & 0 deletions unix/zsyscall_openbsd_arm.go

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10 changes: 10 additions & 0 deletions unix/zsyscall_openbsd_arm.s
Original file line number Diff line number Diff line change
Expand Up @@ -672,3 +672,13 @@ TEXT libc_utimensat_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_utimensat(SB)
GLOBL ·libc_utimensat_trampoline_addr(SB), RODATA, $4
DATA ·libc_utimensat_trampoline_addr(SB)/4, $libc_utimensat_trampoline<>(SB)

TEXT libc_pledge_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_pledge(SB)
GLOBL ·libc_pledge_trampoline_addr(SB), RODATA, $4
DATA ·libc_pledge_trampoline_addr(SB)/4, $libc_pledge_trampoline<>(SB)

TEXT libc_unveil_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_unveil(SB)
GLOBL ·libc_unveil_trampoline_addr(SB), RODATA, $4
DATA ·libc_unveil_trampoline_addr(SB)/4, $libc_unveil_trampoline<>(SB)
30 changes: 30 additions & 0 deletions unix/zsyscall_openbsd_arm64.go

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.

10 changes: 10 additions & 0 deletions unix/zsyscall_openbsd_arm64.s
Original file line number Diff line number Diff line change
Expand Up @@ -672,3 +672,13 @@ TEXT libc_utimensat_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_utimensat(SB)
GLOBL ·libc_utimensat_trampoline_addr(SB), RODATA, $8
DATA ·libc_utimensat_trampoline_addr(SB)/8, $libc_utimensat_trampoline<>(SB)

TEXT libc_pledge_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_pledge(SB)
GLOBL ·libc_pledge_trampoline_addr(SB), RODATA, $8
DATA ·libc_pledge_trampoline_addr(SB)/8, $libc_pledge_trampoline<>(SB)

TEXT libc_unveil_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_unveil(SB)
GLOBL ·libc_unveil_trampoline_addr(SB), RODATA, $8
DATA ·libc_unveil_trampoline_addr(SB)/8, $libc_unveil_trampoline<>(SB)
30 changes: 30 additions & 0 deletions unix/zsyscall_openbsd_mips64.go

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.

10 changes: 10 additions & 0 deletions unix/zsyscall_openbsd_mips64.s
Original file line number Diff line number Diff line change
Expand Up @@ -672,3 +672,13 @@ TEXT libc_utimensat_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_utimensat(SB)
GLOBL ·libc_utimensat_trampoline_addr(SB), RODATA, $8
DATA ·libc_utimensat_trampoline_addr(SB)/8, $libc_utimensat_trampoline<>(SB)

TEXT libc_pledge_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_pledge(SB)
GLOBL ·libc_pledge_trampoline_addr(SB), RODATA, $8
DATA ·libc_pledge_trampoline_addr(SB)/8, $libc_pledge_trampoline<>(SB)

TEXT libc_unveil_trampoline<>(SB),NOSPLIT,$0-0
JMP libc_unveil(SB)
GLOBL ·libc_unveil_trampoline_addr(SB), RODATA, $8
DATA ·libc_unveil_trampoline_addr(SB)/8, $libc_unveil_trampoline<>(SB)
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