go/misc/cgo
Russ Cox 1dcb5836ad cmd/go: accept only limited compiler and linker flags in #cgo directives
Both gcc and clang accept an option -fplugin=code.so to load
a plugin from the ELF shared object file code.so.
Obviously that plugin can then do anything it wants
during the build. This is contrary to the goal of "go get"
never running untrusted code during the build.
(What happens if you choose to run the result of
the build is your responsibility.)

Disallow this behavior by only allowing a small set of
known command-line flags in #cgo CFLAGS directives
(and #cgo LDFLAGS, etc).

The new restrictions can be adjusted by the environment
variables CGO_CFLAGS_ALLOW, CGO_CFLAGS_DISALLOW,
and so on. See the documentation.

In addition to excluding cgo-defined flags, we also have to
make sure that when we pass file names on the command
line, they don't look like flags. So we now refuse to build
packages containing suspicious file names like -x.go.

A wrinkle in all this is that GNU binutils uniformly accept
@foo on the command line to mean "if the file foo exists,
then substitute its contents for @foo in the command line".
So we must also reject @x.go, flags and flag arguments
beginning with @, and so on.

Fixes #23672, CVE-2018-6574.

Change-Id: I59e7c1355155c335a5c5ae0d2cf8fa7aa313940a
Reviewed-on: https://team-review.git.corp.google.com/209949
Reviewed-by: Ian Lance Taylor <iant@google.com>
2018-02-07 15:35:57 +00:00
..
errors cmd/go: accept only limited compiler and linker flags in #cgo directives 2018-02-07 15:35:57 +00:00
fortran *.bash: always use the same string equality operator 2017-03-14 21:46:31 +00:00
gmp all: make copyright headers consistent with one space after period 2016-05-02 13:43:18 +00:00
life test/run: use go tool compile + link instead of go run when possible 2017-10-31 13:21:05 +00:00
nocgo cmd/ld: really import runtime/cgo for external link 2014-05-20 21:36:50 -07:00
stdio test/run: use go tool compile + link instead of go run when possible 2017-10-31 13:21:05 +00:00
test cmd/cgo: revert CL 49490 "fix for function taking pointer typedef" 2018-02-07 01:20:30 +00:00
testasan
testcarchive cmd/go: correct buildmode test (from "c-header" to "c-shared") 2018-01-11 19:24:35 +00:00
testcshared misc,src: add support for specifying adb flags to the android harness 2018-01-20 21:13:30 +00:00
testgodefs cmd/cgo: add -srcdir option 2016-10-30 19:14:08 +00:00
testplugin misc/cgo/testplugin: unskip test 2017-12-06 18:57:07 +00:00
testsanitizers all: use Fatalf instead of Fatal if format is given 2018-01-10 01:35:45 +00:00
testshared cmd/go: make gccgo -buildmode=shared and -linkshared work again 2018-01-12 05:25:55 +00:00
testsigfwd misc/cgo/testsigfwd: add missing return statement 2016-08-30 21:44:14 +00:00
testso cmd/dist: convert testso test into Go 2015-06-12 04:33:50 +00:00
testsovar misc/cgo/testsovar: needs the `extern` keyword to export variables on non-windows platforms 2015-07-21 18:10:57 +00:00
testtls all: make copyright headers consistent with one space after period 2016-05-02 13:43:18 +00:00