4d90a5c364
platform: Allows sysfs to implement utimesns natively This moves away from `syscall.UtimesNano` as it has intentionally avoided common features in POSIX, such as handling UTIME_NOW and UTIME_OMIT. When we eventually expose this API, users will be free to override `UTIME_NOW` with a fake clock, possibly the same that was supplied to wazero's `ModuleConfig`. Signed-off-by: Adrian Cole <adrian@tetrate.io> Co-authored-by: Edoardo Vacchi <evacchi@users.noreply.github.com>
82 lines
2.3 KiB
Go
82 lines
2.3 KiB
Go
// This uses syscall.Mprotect. Go's SDK only supports this on darwin and linux.
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//go:build darwin || linux || freebsd
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package platform
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import (
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"io"
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"syscall"
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"unsafe"
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)
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func munmapCodeSegment(code []byte) error {
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return syscall.Munmap(code)
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}
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// mmapCodeSegmentAMD64 gives all read-write-exec permission to the mmap region
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// to enter the function. Otherwise, segmentation fault exception is raised.
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func mmapCodeSegmentAMD64(code io.Reader, size int) ([]byte, error) {
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mmapFunc, err := syscall.Mmap(
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-1,
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0,
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size,
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// The region must be RWX: RW for writing native codes, X for executing the region.
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syscall.PROT_READ|syscall.PROT_WRITE|syscall.PROT_EXEC,
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// Anonymous as this is not an actual file, but a memory,
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// Private as this is in-process memory region.
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syscall.MAP_ANON|syscall.MAP_PRIVATE,
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)
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if err != nil {
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return nil, err
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}
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w := &bufWriter{underlying: mmapFunc}
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_, err = io.CopyN(w, code, int64(size))
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return mmapFunc, err
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}
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// mmapCodeSegmentARM64 cannot give all read-write-exec permission to the mmap region.
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// Otherwise, the mmap systemcall would raise an error. Here we give read-write
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// to the region at first, write the native code and then change the perm to
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// read-exec, so we can execute the native code.
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func mmapCodeSegmentARM64(code io.Reader, size int) ([]byte, error) {
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mmapFunc, err := syscall.Mmap(
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-1,
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0,
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size,
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// The region must be RW: RW for writing native codes.
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syscall.PROT_READ|syscall.PROT_WRITE,
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// Anonymous as this is not an actual file, but a memory,
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// Private as this is in-process memory region.
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syscall.MAP_ANON|syscall.MAP_PRIVATE,
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)
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if err != nil {
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return nil, err
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}
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w := &bufWriter{underlying: mmapFunc}
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_, err = io.CopyN(w, code, int64(size))
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if err != nil {
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return nil, err
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}
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// Then we're done with writing code, change the permission to RX.
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err = mprotect(mmapFunc, syscall.PROT_READ|syscall.PROT_EXEC)
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return mmapFunc, err
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}
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// mprotect is like syscall.Mprotect, defined locally so that freebsd compiles.
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func mprotect(b []byte, prot int) (err error) {
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var _p0 unsafe.Pointer
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if len(b) > 0 {
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_p0 = unsafe.Pointer(&b[0])
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} else {
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_p0 = unsafe.Pointer(&_zero)
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}
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_, _, e1 := syscall.Syscall(syscall.SYS_MPROTECT, uintptr(_p0), uintptr(len(b)), uintptr(prot))
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if e1 != 0 {
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err = syscall.Errno(e1)
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}
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return
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}
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