| // Copyright 2018 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Checking of compiler and linker flags. |
| // We must avoid flags like -fplugin=, which can allow |
| // arbitrary code execution during the build. |
| // Do not make changes here without carefully |
| // considering the implications. |
| // (That's why the code is isolated in a file named security.go.) |
| // |
| // Note that -Wl,foo means split foo on commas and pass to |
| // the linker, so that -Wl,-foo,bar means pass -foo bar to |
| // the linker. Similarly -Wa,foo for the assembler and so on. |
| // If any of these are permitted, the wildcard portion must |
| // disallow commas. |
| // |
| // Note also that GNU binutils accept any argument @foo |
| // as meaning "read more flags from the file foo", so we must |
| // guard against any command-line argument beginning with @, |
| // even things like "-I @foo". |
| // We use load.SafeArg (which is even more conservative) |
| // to reject these. |
| // |
| // Even worse, gcc -I@foo (one arg) turns into cc1 -I @foo (two args), |
| // so although gcc doesn't expand the @foo, cc1 will. |
| // So out of paranoia, we reject @ at the beginning of every |
| // flag argument that might be split into its own argument. |
| |
| package work |
| |
| import ( |
| "cmd/go/internal/load" |
| "fmt" |
| "os" |
| "regexp" |
| "strings" |
| ) |
| |
| var re = regexp.MustCompile |
| |
| var validCompilerFlags = []*regexp.Regexp{ |
| re(`-D([A-Za-z_].*)`), |
| re(`-I([^@\-].*)`), |
| re(`-O`), |
| re(`-O([^@\-].*)`), |
| re(`-W`), |
| re(`-W([^@,]+)`), // -Wall but not -Wa,-foo. |
| re(`-f(no-)?blocks`), |
| re(`-f(no-)?common`), |
| re(`-f(no-)?constant-cfstrings`), |
| re(`-f(no-)?exceptions`), |
| re(`-finput-charset=([^@\-].*)`), |
| re(`-f(no-)?lto`), |
| re(`-f(no-)?modules`), |
| re(`-f(no-)?objc-arc`), |
| re(`-f(no-)?omit-frame-pointer`), |
| re(`-f(no-)?openmp(-simd)?`), |
| re(`-f(no-)?permissive`), |
| re(`-f(no-)?(pic|PIC|pie|PIE)`), |
| re(`-f(no-)?rtti`), |
| re(`-f(no-)?split-stack`), |
| re(`-f(no-)?stack-(.+)`), |
| re(`-f(no-)?strict-aliasing`), |
| re(`-fsanitize=(.+)`), |
| re(`-g([^@\-].*)?`), |
| re(`-m(arch|cpu|fpu|tune)=([^@\-].*)`), |
| re(`-m(no-)?avx[0-9a-z.]*`), |
| re(`-m(no-)?ms-bitfields`), |
| re(`-m(no-)?stack-(.+)`), |
| re(`-mmacosx-(.+)`), |
| re(`-mnop-fun-dllimport`), |
| re(`-m(no-)?sse[0-9.]*`), |
| re(`-pedantic(-errors)?`), |
| re(`-pipe`), |
| re(`-pthread`), |
| re(`-?-std=([^@\-].*)`), |
| re(`-x([^@\-].*)`), |
| } |
| |
| var validCompilerFlagsWithNextArg = []string{ |
| "-D", |
| "-I", |
| "-isystem", |
| "-framework", |
| "-x", |
| } |
| |
| var validLinkerFlags = []*regexp.Regexp{ |
| re(`-F([^@\-].*)`), |
| re(`-l([^@\-].*)`), |
| re(`-L([^@\-].*)`), |
| re(`-f(no-)?(pic|PIC|pie|PIE)`), |
| re(`-fsanitize=([^@\-].*)`), |
| re(`-g([^@\-].*)?`), |
| re(`-m(arch|cpu|fpu|tune)=([^@\-].*)`), |
| re(`-(pic|PIC|pie|PIE)`), |
| re(`-pthread`), |
| re(`-?-static([-a-z0-9+]*)`), |
| |
| // Note that any wildcards in -Wl need to exclude comma, |
| // since -Wl splits its argument at commas and passes |
| // them all to the linker uninterpreted. Allowing comma |
| // in a wildcard would allow tunnelling arbitrary additional |
| // linker arguments through one of these. |
| re(`-Wl,--(no-)?as-needed`), |
| re(`-Wl,-Bdynamic`), |
| re(`-Wl,-Bstatic`), |
| re(`-Wl,--disable-new-dtags`), |
| re(`-Wl,--enable-new-dtags`), |
| re(`-Wl,--end-group`), |
| re(`-Wl,-framework,[^,@\-][^,]+`), |
| re(`-Wl,-headerpad_max_install_names`), |
| re(`-Wl,--no-undefined`), |
| re(`-Wl,-rpath,([^,@\-][^,]+)`), |
| re(`-Wl,-search_paths_first`), |
| re(`-Wl,--start-group`), |
| re(`-Wl,-?-unresolved-symbols=[^,]+`), |
| re(`-Wl,--(no-)?warn-([^,]+)`), |
| |
| re(`[a-zA-Z0-9_/].*\.(a|o|obj|dll|dylib|so)`), // direct linker inputs: x.o or libfoo.so (but not -foo.o or @foo.o) |
| } |
| |
| var validLinkerFlagsWithNextArg = []string{ |
| "-F", |
| "-l", |
| "-L", |
| "-framework", |
| "-Wl,-framework", |
| } |
| |
| func checkCompilerFlags(name, source string, list []string) error { |
| return checkFlags(name, source, list, validCompilerFlags, validCompilerFlagsWithNextArg) |
| } |
| |
| func checkLinkerFlags(name, source string, list []string) error { |
| return checkFlags(name, source, list, validLinkerFlags, validLinkerFlagsWithNextArg) |
| } |
| |
| func checkFlags(name, source string, list []string, valid []*regexp.Regexp, validNext []string) error { |
| // Let users override rules with $CGO_CFLAGS_ALLOW, $CGO_CFLAGS_DISALLOW, etc. |
| var ( |
| allow *regexp.Regexp |
| disallow *regexp.Regexp |
| ) |
| if env := os.Getenv("CGO_" + name + "_ALLOW"); env != "" { |
| r, err := regexp.Compile(env) |
| if err != nil { |
| return fmt.Errorf("parsing $CGO_%s_ALLOW: %v", name, err) |
| } |
| allow = r |
| } |
| if env := os.Getenv("CGO_" + name + "_DISALLOW"); env != "" { |
| r, err := regexp.Compile(env) |
| if err != nil { |
| return fmt.Errorf("parsing $CGO_%s_DISALLOW: %v", name, err) |
| } |
| disallow = r |
| } |
| |
| Args: |
| for i := 0; i < len(list); i++ { |
| arg := list[i] |
| if disallow != nil && disallow.FindString(arg) == arg { |
| goto Bad |
| } |
| if allow != nil && allow.FindString(arg) == arg { |
| continue Args |
| } |
| for _, re := range valid { |
| if re.FindString(arg) == arg { // must be complete match |
| continue Args |
| } |
| } |
| for _, x := range validNext { |
| if arg == x { |
| if i+1 < len(list) && load.SafeArg(list[i+1]) { |
| i++ |
| continue Args |
| } |
| |
| // Permit -Wl,-framework -Wl,name. |
| if i+1 < len(list) && |
| strings.HasPrefix(arg, "-Wl,") && |
| strings.HasPrefix(list[i+1], "-Wl,") && |
| load.SafeArg(list[i+1][4:]) && |
| !strings.Contains(list[i+1][4:], ",") { |
| i++ |
| continue Args |
| } |
| |
| if i+1 < len(list) { |
| return fmt.Errorf("invalid flag in %s: %s %s (see https://golang.org/s/invalidflag)", source, arg, list[i+1]) |
| } |
| return fmt.Errorf("invalid flag in %s: %s without argument (see https://golang.org/s/invalidflag)", source, arg) |
| } |
| } |
| Bad: |
| return fmt.Errorf("invalid flag in %s: %s", source, arg) |
| } |
| return nil |
| } |