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syscall: handle undefined r2 value on linux-ppc64x

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This change fixes two failng tests on linux-ppc64x:

- TestAllThreadsSyscall() exposed a real bug in the ppc64x support:
  - It turns out that the r2 syscall return value is not defined
    on all architectures. Notably linux-ppc64x so address that by
    introducing a private architectural constant in the syscall
    package, archHonorsR2: true if r2 has a determanistic value.

- TestSetuidEtc() was sensitive to /proc/<PID>/status content:
  - The amount of padding space has changed with kernel vintage.
  - Stress testing revealed a race with /proc files disappearing.

Fixes #42178

Change-Id: Ie6fc0b8f2f94a409ac0e5756e73bfce113274709
Reviewed-on: https://go-review.googlesource.com/c/go/+/266202
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
This commit is contained in:
Andrew G. Morgan 2020-10-28 13:35:57 -07:00 committed by Ian Lance Taylor
parent 4fb4291388
commit 3a819e8998
11 changed files with 91 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/syscall/syscall_linux.go
View File

@ -1003,7 +1003,9 @@ func (pc *allThreadsCaller) doSyscall(initial bool) bool {
pc.r1 = r1
pc.r2 = r2
pc.err = err
} else if pc.r1 != r1 || pc.r2 != r2 || pc.err != err {
} else if pc.r1 != r1 || (archHonorsR2 && pc.r2 != r2) || pc.err != err {
print("trap:", pc.trap, ", a123=[", pc.a1, ",", pc.a2, ",", pc.a3, "]\n")
print("results: got {r1=", r1, ",r2=", r2, ",err=", err, "}, want {r1=", pc.r1, ",r2=", pc.r2, ",r3=", pc.err, "}\n")
panic("AllThreadsSyscall results differ between threads; runtime corrupted")
}
return err == 0
@ -1019,7 +1021,9 @@ func (pc *allThreadsCaller) doSyscall6(initial bool) bool {
pc.r1 = r1
pc.r2 = r2
pc.err = err
} else if pc.r1 != r1 || pc.r2 != r2 || pc.err != err {
} else if pc.r1 != r1 || (archHonorsR2 && pc.r2 != r2) || pc.err != err {
print("trap:", pc.trap, ", a123456=[", pc.a1, ",", pc.a2, ",", pc.a3, ",", pc.a4, ",", pc.a5, ",", pc.a6, "]\n")
print("results: got {r1=", r1, ",r2=", r2, ",err=", err, "}, want {r1=", pc.r1, ",r2=", pc.r2, ",r3=", pc.err, "}\n")
panic("AllThreadsSyscall6 results differ between threads; runtime corrupted")
}
return err == 0

6
src/syscall/syscall_linux_386.go
View File

@ -6,6 +6,12 @@ package syscall
import "unsafe"
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall".
const archHonorsR2 = true
const _SYS_setgroups = SYS_SETGROUPS32
func setTimespec(sec, nsec int64) Timespec {

6
src/syscall/syscall_linux_amd64.go
View File

@ -4,6 +4,12 @@
package syscall
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall".
const archHonorsR2 = true
const _SYS_setgroups = SYS_SETGROUPS
//sys Dup2(oldfd int, newfd int) (err error)

6
src/syscall/syscall_linux_arm.go
View File

@ -6,6 +6,12 @@ package syscall
import "unsafe"
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall". [EABI assumed.]
const archHonorsR2 = true
const _SYS_setgroups = SYS_SETGROUPS32
func setTimespec(sec, nsec int64) Timespec {

6
src/syscall/syscall_linux_arm64.go
View File

@ -6,6 +6,12 @@ package syscall
import "unsafe"
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall".
const archHonorsR2 = true
const _SYS_setgroups = SYS_SETGROUPS
func EpollCreate(size int) (fd int, err error) {

6
src/syscall/syscall_linux_mips64x.go
View File

@ -7,6 +7,12 @@
package syscall
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall".
const archHonorsR2 = true
const _SYS_setgroups = SYS_SETGROUPS
//sys Dup2(oldfd int, newfd int) (err error)

6
src/syscall/syscall_linux_mipsx.go
View File

@ -9,6 +9,12 @@ package syscall
import "unsafe"
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall".
const archHonorsR2 = true
const _SYS_setgroups = SYS_SETGROUPS
func Syscall9(trap, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err Errno)

6
src/syscall/syscall_linux_ppc64x.go
View File

@ -7,6 +7,12 @@
package syscall
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall".
const archHonorsR2 = false
const _SYS_setgroups = SYS_SETGROUPS
//sys Dup2(oldfd int, newfd int) (err error)

6
src/syscall/syscall_linux_riscv64.go
View File

@ -6,6 +6,12 @@ package syscall
import "unsafe"
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall".
const archHonorsR2 = true
const _SYS_setgroups = SYS_SETGROUPS
func EpollCreate(size int) (fd int, err error) {

6
src/syscall/syscall_linux_s390x.go
View File

@ -6,6 +6,12 @@ package syscall
import "unsafe"
// archHonorsR2 captures the fact that r2 is honored by the
// runtime.GOARCH. Syscall conventions are generally r1, r2, err :=
// syscall(trap, ...). Not all architectures define r2 in their
// ABI. See "man syscall".
const archHonorsR2 = true
const _SYS_setgroups = SYS_SETGROUPS
//sys Dup2(oldfd int, newfd int) (err error)

60
src/syscall/syscall_linux_test.go
View File

@ -410,9 +410,6 @@ const (
// syscalls that execute on all OSThreads - with which to support
// POSIX semantics for security state changes.
func TestAllThreadsSyscall(t *testing.T) {
if runtime.GOARCH == "ppc64" {
t.Skip("skipping on linux/ppc64; see issue #42178")
}
if _, _, err := syscall.AllThreadsSyscall(syscall.SYS_PRCTL, PR_SET_KEEPCAPS, 0, 0); err == syscall.ENOTSUP {
t.Skip("AllThreadsSyscall disabled with cgo")
}
@ -544,7 +541,7 @@ func TestAllThreadsSyscall(t *testing.T) {
// compareStatus is used to confirm the contents of the thread
// specific status files match expectations.
func compareStatus(filter, expect string) error {
expected := filter + "\t" + expect
expected := filter + expect
pid := syscall.Getpid()
fs, err := ioutil.ReadDir(fmt.Sprintf("/proc/%d/task", pid))
if err != nil {
@ -553,14 +550,22 @@ func compareStatus(filter, expect string) error {
for _, f := range fs {
tf := fmt.Sprintf("/proc/%s/status", f.Name())
d, err := ioutil.ReadFile(tf)
if os.IsNotExist(err) {
// We are racing against threads dying, which
// is out of our control, so ignore the
// missing file and skip to the next one.
continue
}
if err != nil {
return fmt.Errorf("unable to read %q: %v", tf, err)
}
lines := strings.Split(string(d), "\n")
for _, line := range lines {
// Different kernel vintages pad differently.
line = strings.TrimSpace(line)
if strings.HasPrefix(line, filter) {
if line != expected {
return fmt.Errorf("%s %s (bad)\n", tf, line)
return fmt.Errorf("%q got:%q want:%q (bad)\n", tf, line, expected)
}
break
}
@ -580,9 +585,6 @@ func compareStatus(filter, expect string) error {
// the syscalls. Care should be taken to mirror any enhancements to
// this test here in that file too.
func TestSetuidEtc(t *testing.T) {
if runtime.GOARCH == "ppc64" {
t.Skip("skipping on linux/ppc64; see issue #42178")
}
if syscall.Getuid() != 0 {
t.Skip("skipping root only test")
}
@ -591,34 +593,34 @@ func TestSetuidEtc(t *testing.T) {
fn func() error
filter, expect string
}{
{call: "Setegid(1)", fn: func() error { return syscall.Setegid(1) }, filter: "Gid:", expect: "0\t1\t0\t1"},
{call: "Setegid(0)", fn: func() error { return syscall.Setegid(0) }, filter: "Gid:", expect: "0\t0\t0\t0"},
{call: "Setegid(1)", fn: func() error { return syscall.Setegid(1) }, filter: "Gid:", expect: "\t0\t1\t0\t1"},
{call: "Setegid(0)", fn: func() error { return syscall.Setegid(0) }, filter: "Gid:", expect: "\t0\t0\t0\t0"},
{call: "Seteuid(1)", fn: func() error { return syscall.Seteuid(1) }, filter: "Uid:", expect: "0\t1\t0\t1"},
{call: "Setuid(0)", fn: func() error { return syscall.Setuid(0) }, filter: "Uid:", expect: "0\t0\t0\t0"},
{call: "Seteuid(1)", fn: func() error { return syscall.Seteuid(1) }, filter: "Uid:", expect: "\t0\t1\t0\t1"},
{call: "Setuid(0)", fn: func() error { return syscall.Setuid(0) }, filter: "Uid:", expect: "\t0\t0\t0\t0"},
{call: "Setgid(1)", fn: func() error { return syscall.Setgid(1) }, filter: "Gid:", expect: "1\t1\t1\t1"},
{call: "Setgid(0)", fn: func() error { return syscall.Setgid(0) }, filter: "Gid:", expect: "0\t0\t0\t0"},
{call: "Setgid(1)", fn: func() error { return syscall.Setgid(1) }, filter: "Gid:", expect: "\t1\t1\t1\t1"},
{call: "Setgid(0)", fn: func() error { return syscall.Setgid(0) }, filter: "Gid:", expect: "\t0\t0\t0\t0"},
{call: "Setgroups([]int{0,1,2,3})", fn: func() error { return syscall.Setgroups([]int{0, 1, 2, 3}) }, filter: "Groups:", expect: "0 1 2 3 "},
{call: "Setgroups(nil)", fn: func() error { return syscall.Setgroups(nil) }, filter: "Groups:", expect: " "},
{call: "Setgroups([]int{0})", fn: func() error { return syscall.Setgroups([]int{0}) }, filter: "Groups:", expect: "0 "},
{call: "Setgroups([]int{0,1,2,3})", fn: func() error { return syscall.Setgroups([]int{0, 1, 2, 3}) }, filter: "Groups:", expect: "\t0 1 2 3"},
{call: "Setgroups(nil)", fn: func() error { return syscall.Setgroups(nil) }, filter: "Groups:", expect: ""},
{call: "Setgroups([]int{0})", fn: func() error { return syscall.Setgroups([]int{0}) }, filter: "Groups:", expect: "\t0"},
{call: "Setregid(101,0)", fn: func() error { return syscall.Setregid(101, 0) }, filter: "Gid:", expect: "101\t0\t0\t0"},
{call: "Setregid(0,102)", fn: func() error { return syscall.Setregid(0, 102) }, filter: "Gid:", expect: "0\t102\t102\t102"},
{call: "Setregid(0,0)", fn: func() error { return syscall.Setregid(0, 0) }, filter: "Gid:", expect: "0\t0\t0\t0"},
{call: "Setregid(101,0)", fn: func() error { return syscall.Setregid(101, 0) }, filter: "Gid:", expect: "\t101\t0\t0\t0"},
{call: "Setregid(0,102)", fn: func() error { return syscall.Setregid(0, 102) }, filter: "Gid:", expect: "\t0\t102\t102\t102"},
{call: "Setregid(0,0)", fn: func() error { return syscall.Setregid(0, 0) }, filter: "Gid:", expect: "\t0\t0\t0\t0"},
{call: "Setreuid(1,0)", fn: func() error { return syscall.Setreuid(1, 0) }, filter: "Uid:", expect: "1\t0\t0\t0"},
{call: "Setreuid(0,2)", fn: func() error { return syscall.Setreuid(0, 2) }, filter: "Uid:", expect: "0\t2\t2\t2"},
{call: "Setreuid(0,0)", fn: func() error { return syscall.Setreuid(0, 0) }, filter: "Uid:", expect: "0\t0\t0\t0"},
{call: "Setreuid(1,0)", fn: func() error { return syscall.Setreuid(1, 0) }, filter: "Uid:", expect: "\t1\t0\t0\t0"},
{call: "Setreuid(0,2)", fn: func() error { return syscall.Setreuid(0, 2) }, filter: "Uid:", expect: "\t0\t2\t2\t2"},
{call: "Setreuid(0,0)", fn: func() error { return syscall.Setreuid(0, 0) }, filter: "Uid:", expect: "\t0\t0\t0\t0"},
{call: "Setresgid(101,0,102)", fn: func() error { return syscall.Setresgid(101, 0, 102) }, filter: "Gid:", expect: "101\t0\t102\t0"},
{call: "Setresgid(0,102,101)", fn: func() error { return syscall.Setresgid(0, 102, 101) }, filter: "Gid:", expect: "0\t102\t101\t102"},
{call: "Setresgid(0,0,0)", fn: func() error { return syscall.Setresgid(0, 0, 0) }, filter: "Gid:", expect: "0\t0\t0\t0"},
{call: "Setresgid(101,0,102)", fn: func() error { return syscall.Setresgid(101, 0, 102) }, filter: "Gid:", expect: "\t101\t0\t102\t0"},
{call: "Setresgid(0,102,101)", fn: func() error { return syscall.Setresgid(0, 102, 101) }, filter: "Gid:", expect: "\t0\t102\t101\t102"},
{call: "Setresgid(0,0,0)", fn: func() error { return syscall.Setresgid(0, 0, 0) }, filter: "Gid:", expect: "\t0\t0\t0\t0"},
{call: "Setresuid(1,0,2)", fn: func() error { return syscall.Setresuid(1, 0, 2) }, filter: "Uid:", expect: "1\t0\t2\t0"},
{call: "Setresuid(0,2,1)", fn: func() error { return syscall.Setresuid(0, 2, 1) }, filter: "Uid:", expect: "0\t2\t1\t2"},
{call: "Setresuid(0,0,0)", fn: func() error { return syscall.Setresuid(0, 0, 0) }, filter: "Uid:", expect: "0\t0\t0\t0"},
{call: "Setresuid(1,0,2)", fn: func() error { return syscall.Setresuid(1, 0, 2) }, filter: "Uid:", expect: "\t1\t0\t2\t0"},
{call: "Setresuid(0,2,1)", fn: func() error { return syscall.Setresuid(0, 2, 1) }, filter: "Uid:", expect: "\t0\t2\t1\t2"},
{call: "Setresuid(0,0,0)", fn: func() error { return syscall.Setresuid(0, 0, 0) }, filter: "Uid:", expect: "\t0\t0\t0\t0"},
}
for i, v := range vs {