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cmd/link: support full relro #45681

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cmd/link: support full relro #45681

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3fc8a90
cmd/link: support full relro
Foxboron Feb 24, 2021
cfeecf9
cmd/go: Remove -Wl,-z,relro,-z,now test case
Foxboron Apr 22, 2021
b2601e7
cmd/link: change flag from -l to -relro={true,false}
Foxboron Apr 22, 2021
b85c7f7
cmd/link: change flag from -relro to -bindnow
Foxboron May 6, 2022
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3 changes: 3 additions & 0 deletions src/cmd/link/doc.go
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,9 @@ Flags:
instead of $GOROOT/pkg/$GOOS_$GOARCH.
-k symbol
Set field tracking symbol. Use this flag when GOEXPERIMENT=fieldtrack is set.
-bindnow
When linking externally and marking variables read-only after relocation, also require
immediate function binding (default true)
-libgcc file
Set name of compiler support library.
This is only used in internal link mode.
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19 changes: 15 additions & 4 deletions src/cmd/link/internal/ld/lib.go
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Expand Up @@ -1404,6 +1404,17 @@ func (ctxt *Link) hostlink() {
return argv
}

// Enables Full/Partial RELRO.
addRELROargs := func(argv []string) []string {
relro := "-Wl,-z,relro"
// Enable Full RELRO
if *FlagBindNow {
relro += ",-z,now"
}
argv = append(argv, relro)
return argv
}

switch ctxt.BuildMode {
case BuildModeExe:
if ctxt.HeadType == objabi.Hdarwin {
Expand All @@ -1420,7 +1431,7 @@ func (ctxt *Link) hostlink() {
default:
// ELF.
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
argv = addRELROargs(argv)
}
argv = append(argv, "-pie")
}
Expand All @@ -1429,7 +1440,7 @@ func (ctxt *Link) hostlink() {
argv = append(argv, "-dynamiclib")
} else {
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
argv = addRELROargs(argv)
}
argv = append(argv, "-shared")
if ctxt.HeadType == objabi.Hwindows {
Expand All @@ -1444,15 +1455,15 @@ func (ctxt *Link) hostlink() {
}
case BuildModeShared:
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
argv = addRELROargs(argv)
}
argv = append(argv, "-shared")
case BuildModePlugin:
if ctxt.HeadType == objabi.Hdarwin {
argv = append(argv, "-dynamiclib")
} else {
if ctxt.UseRelro() {
argv = append(argv, "-Wl,-z,relro")
argv = addRELROargs(argv)
}
argv = append(argv, "-shared")
}
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1 change: 1 addition & 0 deletions src/cmd/link/internal/ld/main.go
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Expand Up @@ -95,6 +95,7 @@ var (
FlagDebugTextSize = flag.Int("debugtextsize", 0, "debug text section max size")
flagDebugNosplit = flag.Bool("debugnosplit", false, "dump nosplit call graph")
FlagStrictDups = flag.Int("strictdups", 0, "sanity check duplicate symbol contents during object file reading (1=warn 2=err).")
FlagBindNow = flag.Bool("bindnow", true, "bind function calls when linking externally")
FlagRound = flag.Int("R", -1, "set address rounding `quantum`")
FlagTextAddr = flag.Int64("T", -1, "set text segment `address`")
flagEntrySymbol = flag.String("E", "", "set `entry` symbol name")
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