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cmd/link: move .dynamic and .got sections to relro if applicable

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This is the second of two CLs to roll forward the changes in CL
473495, which was subsequently reverted.

In this patch we move the .dynamic and .got sections from the writable
data segment to the relro segment if the platform supports relro and
we're producing a PIE binary, and also moves .got.plt into relro if
eager binding is in effect (e.g. -bindnow or -Wl,-z,now).

Updates #45681.

Change-Id: I9f4fba6e825b96d1b5e27fb75844450dd0a650b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/571417
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Than McIntosh 2024-03-13 19:03:43 +00:00
parent 7f76c00fc5
commit 2dddc7ef88
5 changed files with 121 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
src/cmd/link/internal/ld/data.go
View File

@ -1850,7 +1850,7 @@ func (state *dodataState) allocateDataSections(ctxt *Link) {
}
ldr := ctxt.loader
// .got
// writable .got (note that for PIE binaries .got goes in relro)
if len(state.data[sym.SELFGOT]) > 0 {
state.allocateNamedSectionAndAssignSyms(&Segdata, ".got", sym.SELFGOT, sym.SDATA, 06)
}
@ -2106,6 +2106,7 @@ func (state *dodataState) allocateDataSections(ctxt *Link) {
xcoffUpdateOuterSize(ctxt, state.datsize-symnStartValue, symn)
}
}
state.assignToSection(sect, sym.SELFRELROSECT, sym.SRODATA)
sect.Length = uint64(state.datsize) - sect.Vaddr
}

20
src/cmd/link/internal/ld/elf.go
View File

@ -1113,6 +1113,7 @@ func elfphload(seg *sym.Segment) *ElfPhdr {
func elfphrelro(seg *sym.Segment) {
ph := newElfPhdr()
ph.Type = elf.PT_GNU_RELRO
ph.Flags = elf.PF_R
ph.Vaddr = seg.Vaddr
ph.Paddr = seg.Vaddr
ph.Memsz = seg.Length
@ -1562,7 +1563,11 @@ func (ctxt *Link) doelf() {
/* global offset table */
got := ldr.CreateSymForUpdate(".got", 0)
got.SetType(sym.SELFGOT) // writable
if ctxt.UseRelro() {
got.SetType(sym.SELFRELROSECT)
} else {
got.SetType(sym.SELFGOT) // writable
}
/* ppc64 glink resolver */
if ctxt.IsPPC64() {
@ -1575,7 +1580,11 @@ func (ctxt *Link) doelf() {
hash.SetType(sym.SELFROSECT)
gotplt := ldr.CreateSymForUpdate(".got.plt", 0)
gotplt.SetType(sym.SELFSECT) // writable
if ctxt.UseRelro() && *flagBindNow {
gotplt.SetType(sym.SELFRELROSECT)
} else {
gotplt.SetType(sym.SELFSECT) // writable
}
plt := ldr.CreateSymForUpdate(".plt", 0)
if ctxt.IsPPC64() {
@ -1597,9 +1606,12 @@ func (ctxt *Link) doelf() {
/* define dynamic elf table */
dynamic := ldr.CreateSymForUpdate(".dynamic", 0)
if thearch.ELF.DynamicReadOnly {
switch {
case thearch.ELF.DynamicReadOnly:
dynamic.SetType(sym.SELFROSECT)
} else {
case ctxt.UseRelro():
dynamic.SetType(sym.SELFRELROSECT)
default:
dynamic.SetType(sym.SELFSECT)
}

58
src/cmd/link/internal/ld/elf_test.go
View File

@ -198,6 +198,7 @@ func TestElfBindNow(t *testing.T) {
name string
args []string
prog string
wantSecsRO []string
mustHaveBuildModePIE bool
mustHaveCGO bool
mustInternalLink bool
@ -213,6 +214,7 @@ func TestElfBindNow(t *testing.T) {
mustHaveBuildModePIE: true,
mustInternalLink: true,
wantDf1Pie: true,
wantSecsRO: []string{".dynamic", ".got"},
},
{
name: "bindnow-linkmode-internal",
@ -232,6 +234,7 @@ func TestElfBindNow(t *testing.T) {
wantDfBindNow: true,
wantDf1Now: true,
wantDf1Pie: true,
wantSecsRO: []string{".dynamic", ".got", ".got.plt"},
},
{
name: "bindnow-pie-linkmode-external",
@ -242,6 +245,8 @@ func TestElfBindNow(t *testing.T) {
wantDfBindNow: true,
wantDf1Now: true,
wantDf1Pie: true,
// NB: external linker produces .plt.got, not .got.plt
wantSecsRO: []string{".dynamic", ".got"},
},
}
@ -251,10 +256,14 @@ func TestElfBindNow(t *testing.T) {
return true
}
}
return false
}
segContainsSec := func(p *elf.Prog, s *elf.Section) bool {
return s.Addr >= p.Vaddr &&
s.Addr+s.FileSize <= p.Vaddr+p.Filesz
}
for _, test := range tests {
t.Run(test.name, func(t *testing.T) {
if test.mustInternalLink {
@ -329,6 +338,53 @@ func TestElfBindNow(t *testing.T) {
if gotDf1Pie := gotDynFlag(flags1, uint64(elf.DF_1_PIE)); gotDf1Pie != test.wantDf1Pie {
t.Fatalf("DT_FLAGS_1 DF_1_PIE got: %v, want: %v", gotDf1Pie, test.wantDf1Pie)
}
for _, wsroname := range test.wantSecsRO {
// Locate section of interest.
var wsro *elf.Section
for _, s := range elfFile.Sections {
if s.Name == wsroname {
wsro = s
break
}
}
if wsro == nil {
t.Fatalf("test %s: can't locate %q section",
test.name, wsroname)
}
// Now walk the program headers. Section should be part of
// some segment that is readonly.
foundRO := false
foundSegs := []*elf.Prog{}
for _, p := range elfFile.Progs {
if segContainsSec(p, wsro) {
foundSegs = append(foundSegs, p)
if p.Flags == elf.PF_R {
foundRO = true
}
}
}
if !foundRO {
// Things went off the rails. Write out some
// useful information for a human looking at the
// test failure.
t.Logf("test %s: %q section not in readonly segment",
wsro.Name, test.name)
t.Logf("section %s location: st=0x%x en=0x%x\n",
wsro.Name, wsro.Addr, wsro.Addr+wsro.FileSize)
t.Logf("sec %s found in these segments: ", wsro.Name)
for _, p := range foundSegs {
t.Logf(" %q", p.Type)
}
t.Logf("\nall segments: \n")
for k, p := range elfFile.Progs {
t.Logf("%d t=%s fl=%s st=0x%x en=0x%x\n",
k, p.Type, p.Flags, p.Vaddr, p.Vaddr+p.Filesz)
}
t.Fatalf("test %s failed", test.name)
}
}
})
}
}

1
src/cmd/link/internal/sym/symkind.go
View File

@ -76,6 +76,7 @@ const (
SGCBITSRELRO
SRODATARELRO
SFUNCTABRELRO
SELFRELROSECT
// Part of .data.rel.ro if it exists, otherwise part of .rodata.
STYPELINK

89
src/cmd/link/internal/sym/symkind_string.go
View File

@ -27,53 +27,54 @@ func _() {
_ = x[SGCBITSRELRO-16]
_ = x[SRODATARELRO-17]
_ = x[SFUNCTABRELRO-18]
_ = x[STYPELINK-19]
_ = x[SITABLINK-20]
_ = x[SSYMTAB-21]
_ = x[SPCLNTAB-22]
_ = x[SFirstWritable-23]
_ = x[SBUILDINFO-24]
_ = x[SELFSECT-25]
_ = x[SMACHO-26]
_ = x[SMACHOGOT-27]
_ = x[SWINDOWS-28]
_ = x[SELFGOT-29]
_ = x[SNOPTRDATA-30]
_ = x[SINITARR-31]
_ = x[SDATA-32]
_ = x[SXCOFFTOC-33]
_ = x[SBSS-34]
_ = x[SNOPTRBSS-35]
_ = x[SLIBFUZZER_8BIT_COUNTER-36]
_ = x[SCOVERAGE_COUNTER-37]
_ = x[SCOVERAGE_AUXVAR-38]
_ = x[STLSBSS-39]
_ = x[SXREF-40]
_ = x[SMACHOSYMSTR-41]
_ = x[SMACHOSYMTAB-42]
_ = x[SMACHOINDIRECTPLT-43]
_ = x[SMACHOINDIRECTGOT-44]
_ = x[SFILEPATH-45]
_ = x[SDYNIMPORT-46]
_ = x[SHOSTOBJ-47]
_ = x[SUNDEFEXT-48]
_ = x[SDWARFSECT-49]
_ = x[SDWARFCUINFO-50]
_ = x[SDWARFCONST-51]
_ = x[SDWARFFCN-52]
_ = x[SDWARFABSFCN-53]
_ = x[SDWARFTYPE-54]
_ = x[SDWARFVAR-55]
_ = x[SDWARFRANGE-56]
_ = x[SDWARFLOC-57]
_ = x[SDWARFLINES-58]
_ = x[SSEHUNWINDINFO-59]
_ = x[SSEHSECT-60]
_ = x[SELFRELROSECT-19]
_ = x[STYPELINK-20]
_ = x[SITABLINK-21]
_ = x[SSYMTAB-22]
_ = x[SPCLNTAB-23]
_ = x[SFirstWritable-24]
_ = x[SBUILDINFO-25]
_ = x[SELFSECT-26]
_ = x[SMACHO-27]
_ = x[SMACHOGOT-28]
_ = x[SWINDOWS-29]
_ = x[SELFGOT-30]
_ = x[SNOPTRDATA-31]
_ = x[SINITARR-32]
_ = x[SDATA-33]
_ = x[SXCOFFTOC-34]
_ = x[SBSS-35]
_ = x[SNOPTRBSS-36]
_ = x[SLIBFUZZER_8BIT_COUNTER-37]
_ = x[SCOVERAGE_COUNTER-38]
_ = x[SCOVERAGE_AUXVAR-39]
_ = x[STLSBSS-40]
_ = x[SXREF-41]
_ = x[SMACHOSYMSTR-42]
_ = x[SMACHOSYMTAB-43]
_ = x[SMACHOINDIRECTPLT-44]
_ = x[SMACHOINDIRECTGOT-45]
_ = x[SFILEPATH-46]
_ = x[SDYNIMPORT-47]
_ = x[SHOSTOBJ-48]
_ = x[SUNDEFEXT-49]
_ = x[SDWARFSECT-50]
_ = x[SDWARFCUINFO-51]
_ = x[SDWARFCONST-52]
_ = x[SDWARFFCN-53]
_ = x[SDWARFABSFCN-54]
_ = x[SDWARFTYPE-55]
_ = x[SDWARFVAR-56]
_ = x[SDWARFRANGE-57]
_ = x[SDWARFLOC-58]
_ = x[SDWARFLINES-59]
_ = x[SSEHUNWINDINFO-60]
_ = x[SSEHSECT-61]
}
const _SymKind_name = "SxxxSTEXTSELFRXSECTSMACHOPLTSTYPESSTRINGSGOSTRINGSGOFUNCSGCBITSSRODATASFUNCTABSELFROSECTSTYPERELROSSTRINGRELROSGOSTRINGRELROSGOFUNCRELROSGCBITSRELROSRODATARELROSFUNCTABRELROSTYPELINKSITABLINKSSYMTABSPCLNTABSFirstWritableSBUILDINFOSELFSECTSMACHOSMACHOGOTSWINDOWSSELFGOTSNOPTRDATASINITARRSDATASXCOFFTOCSBSSSNOPTRBSSSLIBFUZZER_8BIT_COUNTERSCOVERAGE_COUNTERSCOVERAGE_AUXVARSTLSBSSSXREFSMACHOSYMSTRSMACHOSYMTABSMACHOINDIRECTPLTSMACHOINDIRECTGOTSFILEPATHSDYNIMPORTSHOSTOBJSUNDEFEXTSDWARFSECTSDWARFCUINFOSDWARFCONSTSDWARFFCNSDWARFABSFCNSDWARFTYPESDWARFVARSDWARFRANGESDWARFLOCSDWARFLINESSSEHUNWINDINFOSSEHSECT"
const _SymKind_name = "SxxxSTEXTSELFRXSECTSMACHOPLTSTYPESSTRINGSGOSTRINGSGOFUNCSGCBITSSRODATASFUNCTABSELFROSECTSTYPERELROSSTRINGRELROSGOSTRINGRELROSGOFUNCRELROSGCBITSRELROSRODATARELROSFUNCTABRELROSELFRELROSECTSTYPELINKSITABLINKSSYMTABSPCLNTABSFirstWritableSBUILDINFOSELFSECTSMACHOSMACHOGOTSWINDOWSSELFGOTSNOPTRDATASINITARRSDATASXCOFFTOCSBSSSNOPTRBSSSLIBFUZZER_8BIT_COUNTERSCOVERAGE_COUNTERSCOVERAGE_AUXVARSTLSBSSSXREFSMACHOSYMSTRSMACHOSYMTABSMACHOINDIRECTPLTSMACHOINDIRECTGOTSFILEPATHSDYNIMPORTSHOSTOBJSUNDEFEXTSDWARFSECTSDWARFCUINFOSDWARFCONSTSDWARFFCNSDWARFABSFCNSDWARFTYPESDWARFVARSDWARFRANGESDWARFLOCSDWARFLINESSSEHUNWINDINFOSSEHSECT"
var _SymKind_index = [...]uint16{0, 4, 9, 19, 28, 33, 40, 49, 56, 63, 70, 78, 88, 98, 110, 124, 136, 148, 160, 173, 182, 191, 198, 206, 220, 230, 238, 244, 253, 261, 268, 278, 286, 291, 300, 304, 313, 336, 353, 369, 376, 381, 393, 405, 422, 439, 448, 458, 466, 475, 485, 497, 508, 517, 529, 539, 548, 559, 568, 579, 593, 601}
var _SymKind_index = [...]uint16{0, 4, 9, 19, 28, 33, 40, 49, 56, 63, 70, 78, 88, 98, 110, 124, 136, 148, 160, 173, 186, 195, 204, 211, 219, 233, 243, 251, 257, 266, 274, 281, 291, 299, 304, 313, 317, 326, 349, 366, 382, 389, 394, 406, 418, 435, 452, 461, 471, 479, 488, 498, 510, 521, 530, 542, 552, 561, 572, 581, 592, 606, 614}
func (i SymKind) String() string {
if i >= SymKind(len(_SymKind_index)-1) {