Most architectures currently already implement Pipe using the pipe2
syscall. Only 386, amd64 and mips{,le} still use the pipe syscall.
However, some systems (e.g. Android seccomp policies) block that
syscall, see #40828 for an example.
The pipe2 syscall was added in Linux kernel version 2.6.27. The minimum
required Linux kernel version for Go 1.18 will be changed to 2.6.32
per #45964 so it is possible to unify the implementation of Pipe using
the pipe2 syscall.
For #45964
Change-Id: I8ed6a391300c95f3107b4ec6b27d320e42fb535b
Reviewed-on: https://go-review.googlesource.com/c/go/+/350530
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
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 change adds two new methods for invoking system calls
under Linux: syscall.AllThreadsSyscall() and
syscall.AllThreadsSyscall6().
These system call wrappers ensure that all OSThreads mirror
a common system call. The wrappers serialize execution of the
runtime to ensure no race conditions where any Go code observes
a non-atomic OS state change. As such, the syscalls have
higher runtime overhead than regular system calls, and only
need to be used where such thread (or 'm' in the parlance
of the runtime sources) consistency is required.
The new support is used to enable these functions under Linux:
syscall.Setegid(), syscall.Seteuid(), syscall.Setgroups(),
syscall.Setgid(), syscall.Setregid(), syscall.Setreuid(),
syscall.Setresgid(), syscall.Setresuid() and syscall.Setuid().
They work identically to their glibc counterparts.
Extensive discussion of the background issue addressed in this
patch can be found here:
https://github.com/golang/go/issues/1435
In the case where cgo is used, the C runtime can launch pthreads that
are not managed by the Go runtime. As such, the added
syscall.AllThreadsSyscall*() return ENOTSUP when cgo is enabled.
However, for the 9 syscall.Set*() functions listed above, when cgo is
active, these functions redirect to invoke their C.set*() equivalents
in glibc, which wraps the raw system calls with a nptl:setxid fixup
mechanism. This achieves POSIX semantics for these functions in the
combined Go and C runtime.
As a side note, the glibc/nptl:setxid support (2019-11-30) does not
extend to all security related system calls under Linux so using
native Go (CGO_ENABLED=0) and these AllThreadsSyscall*()s, where
needed, will yield more well defined/consistent behavior over all
threads of a Go program. That is, using the
syscall.AllThreadsSyscall*() wrappers for things like setting state
through SYS_PRCTL and SYS_CAPSET etc.
Fixes#1435
Change-Id: Ib1a3e16b9180f64223196a32fc0f9dce14d9105c
Reviewed-on: https://go-review.googlesource.com/c/go/+/210639
Trust: Emmanuel Odeke <emm.odeke@gmail.com>
Trust: Ian Lance Taylor <iant@golang.org>
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Android O and newer blocks the dup2 syscall.
Change-Id: Ibca01fc72ef114deeef6c0450a8b81a556ed0530
Reviewed-on: https://go-review.googlesource.com/c/go/+/235537
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
linux/riscv64 does not provide a renameat syscall and there is no SYS_RENAMEAT
defined in the syscall package. Provide Renameat as a wrapper around renameat2
instead.
Updates #27532
Change-Id: I4864bdf0055e4272920583dcfb0efe2fd40adcbc
Reviewed-on: https://go-review.googlesource.com/c/go/+/212762
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Based on the riscv-go port and the linux/riscv64 files in x/sys/unix.
Updates #27532
Change-Id: Ib33a59a61f6b2721b12292c18f1fc9f9d0509cd3
Reviewed-on: https://go-review.googlesource.com/c/go/+/204659
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
