Parse DWARF information to reduce false positives.

[hctim]

Summary

Help differentiate code and data by parsing DWARF information. This will reduce false positive rates where data is placed in executable sections and is mistakenly parsed as code, resulting in an inflation in the number of indirect CF instructions (and hence an inflation of the number of unprotected).

Also prints the DWARF line data around the region of each indirect CF instruction.

[hctim]

backported a clang-format

[hctim]

Merged previous changes in the stack.

[probinson]

tools/llvm-cfi-verify/FileAnalysis.cpp

325 ↗

(On Diff #118426)

Does this tool run only on .o files, and not on executables? Because this decides line info is valid if any CU has a non-empty line table. If you are looking at a linked executable, one might have been compiled -g and another not, and this check will still succeed.

331 ↗

(On Diff #118426)

Type units can have an associated line table, but that's just to provide filespecs for DW_AT_file. There should never be any Rows in a type unit's line table.

[hctim]

• Modified tool to ensure that users are aware that all statically linked libraries are required to be compiled with '-g'.
• Removed type unit check (thanks probison)!
• Changed opt<uint64_t> to opt<unsigned long long> (known issue with opt<uint64_t>).
• Lexicographically sorted library names.

tools/llvm-cfi-verify/FileAnalysis.cpp

325 ↗

(On Diff #118426)

The goal for this tool is to run on both.

Thanks for reminding me :) I've had discussions with people about this exact topic offline, but forgot to update the commits.

The consensus we reached was in order to do elimination-by-dwarf (i.e. having --ignore-dwarf=false), anything that is statically linked into this binary is required to be compiled with -g. I'll update the documentation for this tool soon and add a comment around this section.

331 ↗

(On Diff #118426)

Thanks for the information, will remove the redundant check.

[hctim]

Patched from upstream.

[pcc]

tools/llvm-cfi-verify/lib/FileAnalysis.cpp

54

I don't think you need cl::location or the external declaration of IgnoreDWARF, because this flag is only used in this file.

unittests/tools/llvm-cfi-verify/FileAnalysis.cpp

485 ↗

(On Diff #119937)

Am I missing something, or should these new tests include DWARF information?

[hctim]

• Fixed diff to be against the correct changelist (prev in stack instead of master).
• Removed external declaration of command line flag .

[pcc]

Should this include a test case?

[hctim]

• Moved DWARF handlers into virtual functions for mocking.
• Added unit tests for line table based instruction exclusion.

[hctim]

• Removed dependency injection onto DWARF lookups from unit tests.
• Added lit test suite for integration testing.
• Added lit tests for checking line table information.

[hctim]

Fixed small formatting issue from revert of dependency injection changes.

[hctim]

Removed tests that require clang with plugin/LTO support. Made the tests build from the supplied assembly instead.

[pcc]

test/tools/llvm-cfi-verify/X86/protected-lineinfo.s

22

I'd prefer if the output were smaller. Do you get a smaller output if you compile with -gmlt?

[hctim]

Compiled integration tests with -gmlt instead of -g

[pcc]

I'd expect there to be a test which makes sure that a jump with no line info in a file with line info doesn't count as an unprotected jump. Can you add one?

test/tools/llvm-cfi-verify/X86/protected-nolineinfo.s

1

I don't think you need more than one test for the line table check. I'd drop this one and keep the other one.

[hctim]

Added test where a file contains line table information, but an indirect CF instruction is not covered by the LT information.

[pcc]

LGTM

test/tools/llvm-cfi-verify/X86/lit.local.cfg

+if not 'X86' in config.root.targets:
+    config.unsupported = True

test/tools/llvm-cfi-verify/X86/protected-lineinfo.s

+# RUN: llvm-mc %s -filetype obj -triple x86_64-linux-elf -o %t.o
+# RUN: llvm-cfi-verify %t.o | FileCheck %s
+
+# CHECK-LABEL: P
+# CHECK-NEXT: tiny.cc:11
+
+# CHECK: Unprotected: 0 (0.00%), Protected: 1 (100.00%)
+
+# Source (tiny.cc):
+#   void a() {}
+#   void b() {}
+#   int main(int argc, char** argv) {
+#     void(*ptr)();
+#     if (argc == 1)
+#       ptr = &a;
+#     else
+#       ptr = &b;
+#     ptr();
+#   }
+# Compile with (output is in tiny.s.0):
+#    clang++ -flto -fsanitize=cfi -fvisibility=hidden -c tiny.cc -o tiny.o -gmlt
+#    clang++ tiny.o -o tiny -flto -fuse-ld=gold -Wl,-plugin-opt,save-temps
+#    clang++ -fsanitize=cfi -flto -fvisibility=hidden -c tiny.cc -o tiny.o -gmlt
+#    llvm-lto2 run @tiny.resolution.txt -o tiny.s -filetype=asm
+
+  .text
+  .file "ld-temp.o"
+  .p2align  4, 0x90
+  .type _Z1av.cfi,@function
+_Z1av.cfi:
+.Lfunc_begin0:
+  .file 1 "tiny.cc"
+  .loc  1 1 0
+  .cfi_startproc
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+.Ltmp0:
+  .loc  1 1 11 prologue_end
+  popq  %rbp
+  retq
+.Ltmp1:
+.Lfunc_end0:
+  .size _Z1av.cfi, .Lfunc_end0-_Z1av.cfi
+  .cfi_endproc
+
+  .p2align  4, 0x90
+  .type _Z1bv.cfi,@function
+_Z1bv.cfi:
+.Lfunc_begin1:
+  .loc  1 2 0
+  .cfi_startproc
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+.Ltmp2:
+  .loc  1 2 11 prologue_end
+  popq  %rbp
+  retq
+.Ltmp3:
+.Lfunc_end1:
+  .size _Z1bv.cfi, .Lfunc_end1-_Z1bv.cfi
+  .cfi_endproc
+
+  .hidden main
+  .globl  main
+  .p2align  4, 0x90
+  .type main,@function
+main:
+.Lfunc_begin2:
+  .loc  1 4 0
+  .cfi_startproc
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+  subq  $32, %rsp
+  movl  $0, -8(%rbp)
+  movl  %edi, -4(%rbp)
+  movq  %rsi, -24(%rbp)
+.Ltmp4:
+  .loc  1 6 12 prologue_end
+  cmpl  $1, -4(%rbp)
+  .loc  1 6 7 is_stmt 0
+  jne .LBB2_2
+  .loc  1 0 7
+  leaq  _Z1av(%rip), %rax
+  .loc  1 7 9 is_stmt 1
+  movq  %rax, -16(%rbp)
+  .loc  1 7 5 is_stmt 0
+  jmp .LBB2_3
+.LBB2_2:
+  .loc  1 0 5
+  leaq  _Z1bv(%rip), %rax
+  .loc  1 9 9 is_stmt 1
+  movq  %rax, -16(%rbp)
+.LBB2_3:
+  .loc  1 0 9 is_stmt 0
+  leaq  .L.cfi.jumptable(%rip), %rcx
+  .loc  1 11 3 is_stmt 1
+  movq  -16(%rbp), %rax
+  movq  %rax, %rdx
+  subq  %rcx, %rdx
+  movq  %rdx, %rcx
+  shrq  $3, %rcx
+  shlq  $61, %rdx
+  orq %rcx, %rdx
+  cmpq  $1, %rdx
+  jbe .LBB2_5
+  ud2
+.LBB2_5:
+  callq *%rax
+  .loc  1 12 1
+  movl  -8(%rbp), %eax
+  addq  $32, %rsp
+  popq  %rbp
+  retq
+.Ltmp5:
+.Lfunc_end2:
+  .size main, .Lfunc_end2-main
+  .cfi_endproc
+
+  .p2align  3, 0x90
+  .type .L.cfi.jumptable,@function
+.L.cfi.jumptable:
+.Lfunc_begin3:
+  .cfi_startproc
+  #APP
+  jmp _Z1av.cfi@PLT
+  int3
+  int3
+  int3
+  jmp _Z1bv.cfi@PLT
+  int3
+  int3
+  int3
+
+  #NO_APP
+.Lfunc_end3:
+  .size .L.cfi.jumptable, .Lfunc_end3-.L.cfi.jumptable
+  .cfi_endproc
+
+  .section  .debug_str,"MS",@progbits,1
+.Linfo_string0:
+  .asciz  "clang version 6.0.0 (trunk 316774)"
+.Linfo_string1:
+  .asciz  "tiny.cc"
+.Linfo_string2:
+  .asciz  ""
+  .section  .debug_abbrev,"",@progbits
+  .byte 1
+  .byte 17
+  .byte 0
+  .byte 37
+  .byte 14
+  .byte 19
+  .byte 5
+  .byte 3
+  .byte 14
+  .byte 16
+  .byte 23
+  .byte 27
+  .byte 14
+  .byte 17
+  .byte 1
+  .byte 18
+  .byte 6
+  .byte 0
+  .byte 0
+  .byte 0
+  .section  .debug_info,"",@progbits
+.Lcu_begin0:
+  .long 38
+  .short  4
+  .long .debug_abbrev
+  .byte 8
+  .byte 1
+  .long .Linfo_string0
+  .short  4
+  .long .Linfo_string1
+  .long .Lline_table_start0
+  .long .Linfo_string2
+  .quad .Lfunc_begin0
+  .long .Lfunc_end2-.Lfunc_begin0
+  .section  .debug_ranges,"",@progbits
+  .section  .debug_macinfo,"",@progbits
+.Lcu_macro_begin0:
+  .byte 0
+
+  .type _Z1av,@function
+_Z1av = .L.cfi.jumptable
+  .type _Z1bv,@function
+_Z1bv = .L.cfi.jumptable+8
+  .ident  "clang version 6.0.0 (trunk 316774)"
+  .section  ".note.GNU-stack","",@progbits
+  .section  .debug_line,"",@progbits
+.Lline_table_start0:
+

test/tools/llvm-cfi-verify/X86/protected-nolineinfo.s

+# RUN: llvm-mc %s -filetype obj -triple x86_64-linux-elf -o %t.o
+# RUN: not llvm-cfi-verify %t.o 2>&1 | FileCheck %s
+
+# CHECK: DWARF line information missing. Did you compile with '-g'?
+
+# Source (tiny.cc):
+#   void a() {}
+#   void b() {}
+#   int main(int argc, char** argv) {
+#     void(*ptr)();
+#     if (argc == 1)
+#       ptr = &a;
+#     else
+#       ptr = &b;
+#     ptr();
+#   }
+# Compile with (output is in tiny.s.0):
+#    clang++ -flto -fsanitize=cfi -fvisibility=hidden -c tiny.cc -o tiny.o
+#    clang++ tiny.o -o tiny -flto -fuse-ld=gold -Wl,-plugin-opt,save-temps
+#    clang++ -fsanitize=cfi -flto -fvisibility=hidden -c tiny.cc -o tiny.o
+#    llvm-lto2 run @tiny.resolution.txt -o tiny.s -filetype=asm
+
+  .text
+  .file "ld-temp.o"
+  .p2align  4, 0x90
+  .type _Z1av.cfi,@function
+_Z1av.cfi:
+  .cfi_startproc
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+  popq  %rbp
+  retq
+.Lfunc_end0:
+  .size _Z1av.cfi, .Lfunc_end0-_Z1av.cfi
+  .cfi_endproc
+
+  .p2align  4, 0x90
+  .type _Z1bv.cfi,@function
+_Z1bv.cfi:
+  .cfi_startproc
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+  popq  %rbp
+  retq
+.Lfunc_end1:
+  .size _Z1bv.cfi, .Lfunc_end1-_Z1bv.cfi
+  .cfi_endproc
+
+  .hidden main
+  .globl  main
+  .p2align  4, 0x90
+  .type main,@function
+main:
+  .cfi_startproc
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+  subq  $32, %rsp
+  movl  $0, -8(%rbp)
+  movl  %edi, -4(%rbp)
+  movq  %rsi, -24(%rbp)
+  cmpl  $1, -4(%rbp)
+  jne .LBB2_2
+  leaq  _Z1av(%rip), %rax
+  movq  %rax, -16(%rbp)
+  jmp .LBB2_3
+.LBB2_2:
+  leaq  _Z1bv(%rip), %rax
+  movq  %rax, -16(%rbp)
+.LBB2_3:
+  leaq  .L.cfi.jumptable(%rip), %rcx
+  movq  -16(%rbp), %rax
+  movq  %rax, %rdx
+  subq  %rcx, %rdx
+  movq  %rdx, %rcx
+  shrq  $3, %rcx
+  shlq  $61, %rdx
+  orq %rcx, %rdx
+  cmpq  $1, %rdx
+  jbe .LBB2_5
+  ud2
+.LBB2_5:
+  callq *%rax
+  movl  -8(%rbp), %eax
+  addq  $32, %rsp
+  popq  %rbp
+  retq
+.Lfunc_end2:
+  .size main, .Lfunc_end2-main
+  .cfi_endproc
+
+  #.section  .text.cfi,"ax",@progbits
+  .p2align  3, 0x90
+  .type .L.cfi.jumptable,@function
+.L.cfi.jumptable:
+  .cfi_startproc
+  #APP
+  jmp _Z1av.cfi@PLT
+  int3
+  int3
+  int3
+  jmp _Z1bv.cfi@PLT
+  int3
+  int3
+  int3
+
+  #NO_APP
+.Lfunc_end3:
+  .size .L.cfi.jumptable, .Lfunc_end3-.L.cfi.jumptable
+  .cfi_endproc
+
+
+  .type _Z1av,@function
+_Z1av = .L.cfi.jumptable
+  .type _Z1bv,@function
+_Z1bv = .L.cfi.jumptable+8
+  .ident  "clang version 6.0.0 (trunk 316774)"
+  .section  ".note.GNU-stack","",@progbits

test/tools/llvm-cfi-verify/X86/unprotected-lineinfo.s

+# RUN: llvm-mc %s -filetype obj -triple x86_64-linux-elf -o %t.o
+# RUN: llvm-cfi-verify %t.o | FileCheck %s
+
+# CHECK-LABEL: U
+# CHECK-NEXT: tiny.cc:11
+
+# CHECK: Unprotected: 1 (100.00%), Protected: 0 (0.00%)
+
+# Source (tiny.cc):
+#   void a() {}
+#   void b() {}
+#   int main(int argc, char** argv) {
+#     void(*ptr)();
+#     if (argc == 1)
+#       ptr = &a;
+#     else
+#       ptr = &b;
+#     ptr();
+#   }
+# Compile with:
+#    clang++ -gmlt tiny.cc -S -o tiny.s
+
+  .text
+  .file "tiny.cc"
+  .globl  _Z1av                   # -- Begin function _Z1av
+  .p2align  4, 0x90
+  .type _Z1av,@function
+_Z1av:                                  # @_Z1av
+.Lfunc_begin0:
+  .file 1 "tiny.cc"
+  .loc  1 1 0                   # tiny.cc:1:0
+  .cfi_startproc
+# BB#0:
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+.Ltmp0:
+  .loc  1 1 11 prologue_end     # tiny.cc:1:11
+  popq  %rbp
+  retq
+.Ltmp1:
+.Lfunc_end0:
+  .size _Z1av, .Lfunc_end0-_Z1av
+  .cfi_endproc
+                                        # -- End function
+  .globl  _Z1bv                   # -- Begin function _Z1bv
+  .p2align  4, 0x90
+  .type _Z1bv,@function
+_Z1bv:                                  # @_Z1bv
+.Lfunc_begin1:
+  .loc  1 2 0                   # tiny.cc:2:0
+  .cfi_startproc
+# BB#0:
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+.Ltmp2:
+  .loc  1 2 11 prologue_end     # tiny.cc:2:11
+  popq  %rbp
+  retq
+.Ltmp3:
+.Lfunc_end1:
+  .size _Z1bv, .Lfunc_end1-_Z1bv
+  .cfi_endproc
+                                        # -- End function
+  .globl  main                    # -- Begin function main
+  .p2align  4, 0x90
+  .type main,@function
+main:                                   # @main
+.Lfunc_begin2:
+  .loc  1 4 0                   # tiny.cc:4:0
+  .cfi_startproc
+# BB#0:
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+  subq  $32, %rsp
+  movl  $0, -4(%rbp)
+  movl  %edi, -8(%rbp)
+  movq  %rsi, -16(%rbp)
+.Ltmp4:
+  .loc  1 6 12 prologue_end     # tiny.cc:6:12
+  cmpl  $1, -8(%rbp)
+  .loc  1 6 7 is_stmt 0         # tiny.cc:6:7
+  jne .LBB2_2
+# BB#1:
+  .loc  1 0 7                   # tiny.cc:0:7
+  movabsq $_Z1av, %rax
+  .loc  1 7 9 is_stmt 1         # tiny.cc:7:9
+  movq  %rax, -24(%rbp)
+  .loc  1 7 5 is_stmt 0         # tiny.cc:7:5
+  jmp .LBB2_3
+.LBB2_2:
+  .loc  1 0 5                   # tiny.cc:0:5
+  movabsq $_Z1bv, %rax
+  .loc  1 9 9 is_stmt 1         # tiny.cc:9:9
+  movq  %rax, -24(%rbp)
+.LBB2_3:
+  .loc  1 11 3                  # tiny.cc:11:3
+  callq *-24(%rbp)
+  .loc  1 12 1                  # tiny.cc:12:1
+  movl  -4(%rbp), %eax
+  addq  $32, %rsp
+  popq  %rbp
+  retq
+.Ltmp5:
+.Lfunc_end2:
+  .size main, .Lfunc_end2-main
+  .cfi_endproc
+                                        # -- End function
+  .section  .debug_str,"MS",@progbits,1
+.Linfo_string0:
+  .asciz  "clang version 6.0.0 (trunk 316774)" # string offset=0
+.Linfo_string1:
+  .asciz  "tiny.cc"               # string offset=35
+.Linfo_string2:
+  .asciz  "/tmp/a/b"              # string offset=43
+  .section  .debug_abbrev,"",@progbits
+  .byte 1                       # Abbreviation Code
+  .byte 17                      # DW_TAG_compile_unit
+  .byte 0                       # DW_CHILDREN_no
+  .byte 37                      # DW_AT_producer
+  .byte 14                      # DW_FORM_strp
+  .byte 19                      # DW_AT_language
+  .byte 5                       # DW_FORM_data2
+  .byte 3                       # DW_AT_name
+  .byte 14                      # DW_FORM_strp
+  .byte 16                      # DW_AT_stmt_list
+  .byte 23                      # DW_FORM_sec_offset
+  .byte 27                      # DW_AT_comp_dir
+  .byte 14                      # DW_FORM_strp
+  .byte 17                      # DW_AT_low_pc
+  .byte 1                       # DW_FORM_addr
+  .byte 18                      # DW_AT_high_pc
+  .byte 6                       # DW_FORM_data4
+  .byte 0                       # EOM(1)
+  .byte 0                       # EOM(2)
+  .byte 0                       # EOM(3)
+  .section  .debug_info,"",@progbits
+.Lcu_begin0:
+  .long 38                      # Length of Unit
+  .short  4                       # DWARF version number
+  .long .debug_abbrev           # Offset Into Abbrev. Section
+  .byte 8                       # Address Size (in bytes)
+  .byte 1                       # Abbrev [1] 0xb:0x1f DW_TAG_compile_unit
+  .long .Linfo_string0          # DW_AT_producer
+  .short  4                       # DW_AT_language
+  .long .Linfo_string1          # DW_AT_name
+  .long .Lline_table_start0     # DW_AT_stmt_list
+  .long .Linfo_string2          # DW_AT_comp_dir
+  .quad .Lfunc_begin0           # DW_AT_low_pc
+  .long .Lfunc_end2-.Lfunc_begin0 # DW_AT_high_pc
+  .section  .debug_ranges,"",@progbits
+  .section  .debug_macinfo,"",@progbits
+.Lcu_macro_begin0:
+  .byte 0                       # End Of Macro List Mark
+
+  .ident  "clang version 6.0.0 (trunk 316774)"
+  .section  ".note.GNU-stack","",@progbits
+  .section  .debug_line,"",@progbits
+.Lline_table_start0:

test/tools/llvm-cfi-verify/X86/unprotected-nolineinfo.s

+# RUN: llvm-mc %s -filetype obj -triple x86_64-linux-elf -o %t.o
+# RUN: not llvm-cfi-verify %t.o 2>&1 | FileCheck %s
+
+# CHECK: DWARF line information missing. Did you compile with '-g'?
+
+# Source (tiny.cc):
+#   void a() {}
+#   void b() {}
+#   int main(int argc, char** argv) {
+#     void(*ptr)();
+#     if (argc == 1)
+#       ptr = &a;
+#     else
+#       ptr = &b;
+#     ptr();
+#   }
+# Compile with:
+#    clang++ tiny.cc -S -o tiny.s
+
+  .text
+  .file "tiny.cc"
+  .globl  _Z1av                   # -- Begin function _Z1av
+  .p2align  4, 0x90
+  .type _Z1av,@function
+_Z1av:                                  # @_Z1av
+  .cfi_startproc
+# BB#0:
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+  popq  %rbp
+  retq
+.Lfunc_end0:
+  .size _Z1av, .Lfunc_end0-_Z1av
+  .cfi_endproc
+                                        # -- End function
+  .globl  _Z1bv                   # -- Begin function _Z1bv
+  .p2align  4, 0x90
+  .type _Z1bv,@function
+_Z1bv:                                  # @_Z1bv
+  .cfi_startproc
+# BB#0:
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+  popq  %rbp
+  retq
+.Lfunc_end1:
+  .size _Z1bv, .Lfunc_end1-_Z1bv
+  .cfi_endproc
+                                        # -- End function
+  .globl  main                    # -- Begin function main
+  .p2align  4, 0x90
+  .type main,@function
+main:                                   # @main
+  .cfi_startproc
+# BB#0:
+  pushq %rbp
+  .cfi_def_cfa_offset 16
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+  .cfi_def_cfa_register %rbp
+  subq  $32, %rsp
+  movl  $0, -4(%rbp)
+  movl  %edi, -8(%rbp)
+  movq  %rsi, -16(%rbp)
+  cmpl  $1, -8(%rbp)
+  jne .LBB2_2
+# BB#1:
+  movabsq $_Z1av, %rax
+  movq  %rax, -24(%rbp)
+  jmp .LBB2_3
+.LBB2_2:
+  movabsq $_Z1bv, %rax
+  movq  %rax, -24(%rbp)
+.LBB2_3:
+  callq *-24(%rbp)
+  movl  -4(%rbp), %eax
+  addq  $32, %rsp
+  popq  %rbp
+  retq
+.Lfunc_end2:
+  .size main, .Lfunc_end2-main
+  .cfi_endproc
+                                        # -- End function
+
+  .ident  "clang version 6.0.0 (trunk 316774)"
+  .section  ".note.GNU-stack","",@progbits

tools/llvm-cfi-verify/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   AllTargetsAsmPrinters
   AllTargetsAsmParsers
   AllTargetsDescs
   AllTargetsDisassemblers
   AllTargetsInfos
+  DebugInfoDWARF
   MC
   MCParser
   Object
   Support
   )
 
 add_llvm_tool(llvm-cfi-verify
   llvm-cfi-verify.cpp)
 
 add_subdirectory(lib)
 target_link_libraries(llvm-cfi-verify LLVMCFIVerify)

tools/llvm-cfi-verify/LLVMBuild.txt

 ;   http://llvm.org/docs/LLVMBuild.html
 ;
 ;===------------------------------------------------------------------------===;
 
 [component_0]
 type = Tool
 name = llvm-cfi-verify
 parent = Tools
-required_libraries = all-targets MC MCDisassembler MCParser Support
+required_libraries = all-targets DebugInfoDWARF MC MCDisassembler MCParser Support

tools/llvm-cfi-verify/lib/CMakeLists.txt

 add_library(LLVMCFIVerify
   STATIC
   FileAnalysis.cpp
   FileAnalysis.h
   GraphBuilder.cpp
   GraphBuilder.h)
 
 llvm_update_compile_flags(LLVMCFIVerify)
 llvm_map_components_to_libnames(libs
+  DebugInfoDWARF
   MC
   MCParser
   Object
   Support)
 target_link_libraries(LLVMCFIVerify ${libs})

tools/llvm-cfi-verify/lib/FileAnalysis.h

 //===- FileAnalysis.h -------------------------------------------*- C++ -*-===//
 //
 //                      The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CFI_VERIFY_FILE_ANALYSIS_H
 #define LLVM_CFI_VERIFY_FILE_ANALYSIS_H
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/BinaryFormat/ELF.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstPrinter.h"
 #include "llvm/MC/MCInstrAnalysis.h"
 #include "llvm/MC/MCInstrDesc.h"
 #include "llvm/MC/MCInstrInfo.h"
public:
 
   // Returns the list of indirect instructions.
   const std::set<uint64_t> &getIndirectInstructions() const;
 
   const MCRegisterInfo *getRegisterInfo() const;
   const MCInstrInfo *getMCInstrInfo() const;
   const MCInstrAnalysis *getMCInstrAnalysis() const;
 
+  // Returns true if this class is using DWARF line tables for elimination.
+  bool hasLineTableInfo() const;
+
+  // Returns the line table information for the range {Address +-
+  // DWARFSearchRange}. Returns an empty table if the address has no valid line
+  // table information, or this analysis object has DWARF handling disabled.
+  DILineInfoTable getLineInfoForAddressRange(uint64_t Address);
+
+  // Returns whether the provided address has valid line information for
+  // instructions in the range of Address +- DWARFSearchRange.
+  bool hasValidLineInfoForAddressRange(uint64_t Address);
+
 protected:
   // Construct a blank object with the provided triple and features. Used in
   // testing, where a sub class will dependency inject protected methods to
   // allow analysis of raw binary, without requiring a fully valid ELF file.
   FileAnalysis(const Triple &ObjectTriple, const SubtargetFeatures &Features);
 
   // Add an instruction to this object.
   void addInstruction(const Instr &Instruction);
private:
   std::unique_ptr<MCSubtargetInfo> SubtargetInfo;
   std::unique_ptr<const MCInstrInfo> MII;
   MCObjectFileInfo MOFI;
   std::unique_ptr<MCContext> Context;
   std::unique_ptr<const MCDisassembler> Disassembler;
   std::unique_ptr<const MCInstrAnalysis> MIA;
   std::unique_ptr<MCInstPrinter> Printer;
 
+  // DWARF debug information.
+  std::unique_ptr<DWARFContext> DWARF;
+
   // A mapping between the virtual memory address to the instruction metadata
-  // struct.
+  // struct. TODO(hctim): Reimplement this as a sorted vector to avoid per-
+  // insertion allocation.
   std::map<uint64_t, Instr> Instructions;
 
   // Contains a mapping between a specific address, and a list of instructions
   // that use this address as a branch target (including call instructions).
   DenseMap<uint64_t, std::vector<uint64_t>> StaticBranchTargetings;
 
   // A list of addresses of indirect control flow instructions.
   std::set<uint64_t> IndirectInstructions;

tools/llvm-cfi-verify/lib/FileAnalysis.cpp

 //===- FileAnalysis.cpp -----------------------------------------*- C++ -*-===//
 //
 //                      The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "FileAnalysis.h"
 #include "GraphBuilder.h"
 
 #include "llvm/BinaryFormat/ELF.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstPrinter.h"
 #include "llvm/MC/MCInstrAnalysis.h"
 #include "llvm/MC/MCInstrDesc.h"
 #include "llvm/MC/MCInstrInfo.h"

 
 #include <functional>
 
 using Instr = llvm::cfi_verify::FileAnalysis::Instr;
 
 namespace llvm {
 namespace cfi_verify {
 
+static cl::opt<bool> IgnoreDWARF(
+    "ignore-dwarf",
+    cl::desc(
+        "Ignore all DWARF data. This relaxes the requirements for all "
+        "statically linked libraries to have been compiled with '-g', but "
+        "will result in false positives for 'CFI unprotected' instructions."),
+    cl::init(false));
+
+cl::opt<unsigned long long> DWARFSearchRange(
+    "dwarf-search-range",
+    cl::desc("Address search range used to determine if instruction is valid."),
+    cl::init(0x10));
+
 Expected<FileAnalysis> FileAnalysis::Create(StringRef Filename) {
   // Open the filename provided.
   Expected<object::OwningBinary<object::Binary>> BinaryOrErr =
       object::createBinary(Filename);
   if (!BinaryOrErr)
     return BinaryOrErr.takeError();
 
   // Construct the object and allow it to take ownership of the binary.
Error FileAnalysis::initialiseDisassemblyMembers() {
   Printer.reset(ObjectTarget->createMCInstPrinter(
       ObjectTriple, AsmInfo->getAssemblerDialect(), *AsmInfo, *MII,
       *RegisterInfo));
 
   return Error::success();
 }
 
 Error FileAnalysis::parseCodeSections() {
+  if (!IgnoreDWARF) {
+    DWARF.reset(DWARFContext::create(*Object).release());
+    if (!DWARF)
+      return make_error<StringError>("Could not create DWARF information.",
+                                     inconvertibleErrorCode());
+
+    bool LineInfoValid = false;
+
+    for (auto &Unit : DWARF->compile_units()) {
+      const auto &LineTable = DWARF->getLineTableForUnit(Unit.get());
+      if (LineTable && !LineTable->Rows.empty()) {
+        LineInfoValid = true;
+        break;
+      }
+    }
+
+    if (!LineInfoValid)
+      return make_error<StringError>(
+          "DWARF line information missing. Did you compile with '-g'?",
+          inconvertibleErrorCode());
+  }
+
   for (const object::SectionRef &Section : Object->sections()) {
     // Ensure only executable sections get analysed.
     if (!(object::ELFSectionRef(Section).getFlags() & ELF::SHF_EXECINSTR))
       continue;
 
     StringRef SectionContents;
     if (Section.getContents(SectionContents))
       return make_error<StringError>("Failed to retrieve section contents",
                                      inconvertibleErrorCode());
 
     ArrayRef<uint8_t> SectionBytes((const uint8_t *)SectionContents.data(),
                                    Section.getSize());
     parseSectionContents(SectionBytes, Section.getAddress());
   }
   return Error::success();
 }
 
+DILineInfoTable FileAnalysis::getLineInfoForAddressRange(uint64_t Address) {
+  if (!hasLineTableInfo())
+    return DILineInfoTable();
+
+  return DWARF->getLineInfoForAddressRange(Address, DWARFSearchRange);
+}
+
+bool FileAnalysis::hasValidLineInfoForAddressRange(uint64_t Address) {
+  return !getLineInfoForAddressRange(Address).empty();
+}
+
+bool FileAnalysis::hasLineTableInfo() const { return DWARF != nullptr; }
+
 void FileAnalysis::parseSectionContents(ArrayRef<uint8_t> SectionBytes,
                                         uint64_t SectionAddress) {
   MCInst Instruction;
   Instr InstrMeta;
   uint64_t InstructionSize;
 
   for (uint64_t Byte = 0; Byte < SectionBytes.size();) {
     bool ValidInstruction =
         Disassembler->getInstruction(Instruction, InstructionSize,
                                      SectionBytes.drop_front(Byte), 0, nulls(),
                                      outs()) == MCDisassembler::Success;
 
     Byte += InstructionSize;
 
     uint64_t VMAddress = SectionAddress + Byte - InstructionSize;
     InstrMeta.Instruction = Instruction;
     InstrMeta.VMAddress = VMAddress;
     InstrMeta.InstructionSize = InstructionSize;
     InstrMeta.Valid = ValidInstruction;
+
+    // Check if this instruction exists in the range of the DWARF metadata.
+    if (hasLineTableInfo() && !hasValidLineInfoForAddressRange(VMAddress))
+      continue;
+
     addInstruction(InstrMeta);
 
     if (!ValidInstruction)
       continue;
 
     // Skip additional parsing for instructions that do not affect the control
     // flow.
     const auto &InstrDesc = MII->get(Instruction.getOpcode());

tools/llvm-cfi-verify/lib/GraphBuilder.cpp

if (!ParentDesc.mayAffectControlFlow(ParentMeta.Instruction,
       // If this cross reference doesn't affect CF, continue the graph.
       buildFlowGraphImpl(Analysis, OpenedNodes, Result, ParentMeta.VMAddress,
                          Depth + 1);
       Result.IntermediateNodes[ParentMeta.VMAddress] = Address;
       HasValidCrossRef = true;
       continue;
     }
 
+    // Call instructions are not valid in the upwards traversal.
+    if (ParentDesc.isCall()) {
+      Result.IntermediateNodes[ParentMeta.VMAddress] = Address;
+      Result.OrphanedNodes.push_back(ParentMeta.VMAddress);
+      continue;
+    }
+
     // Evaluate the branch target to ascertain whether this XRef is the result
     // of a fallthrough or the target of a branch.
     uint64_t BranchTarget;
     if (!Analysis.getMCInstrAnalysis()->evaluateBranch(
             ParentMeta.Instruction, ParentMeta.VMAddress,
             ParentMeta.InstructionSize, BranchTarget)) {
       errs() << "Failed to evaluate branch target for instruction at address "
              << format_hex(ParentMeta.VMAddress, 2) << ".\n";

tools/llvm-cfi-verify/lib/LLVMBuild.txt

 ;   http://llvm.org/docs/LLVMBuild.html
 ;
 ;===------------------------------------------------------------------------===;
 
 [component_0]
 type = Library
 name = CFIVerify
 parent = Libraries
-required_libraries = MC MCDisassembler MCParser Support
+required_libraries = DebugInfoDWARF MC MCDisassembler MCParser Support

tools/llvm-cfi-verify/llvm-cfi-verify.cpp

 //
 //===----------------------------------------------------------------------===//
 
 #include "lib/FileAnalysis.h"
 
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Error.h"
+#include "llvm/Support/FormatVariadic.h"
 
 #include <cstdlib>
 
 using namespace llvm;
 using namespace llvm::object;
 using namespace llvm::cfi_verify;
 
 cl::opt<std::string> InputFilename(cl::Positional, cl::desc("<input file>"),
                                    cl::Required);
 
 ExitOnError ExitOnErr;
 
-void printIndirectCFInstructions(const FileAnalysis &Verifier) {
-  for (uint64_t Address : Verifier.getIndirectInstructions()) {
-    const auto &InstrMeta = Verifier.getInstructionOrDie(Address);
-    outs() << format_hex(Address, 2) << " |"
-           << Verifier.getMCInstrInfo()->getName(
+void printIndirectCFInstructions(FileAnalysis &Analysis) {
+  uint64_t ProtectedCount = 0;
+  uint64_t UnprotectedCount = 0;
+
+  for (uint64_t Address : Analysis.getIndirectInstructions()) {
+    const auto &InstrMeta = Analysis.getInstructionOrDie(Address);
+
+    if (Analysis.isIndirectInstructionCFIProtected(Address)) {
+      outs() << "P ";
+      ProtectedCount++;
+    } else {
+      outs() << "U ";
+      UnprotectedCount++;
+    }
+
+    outs() << format_hex(Address, 2) << " | "
+           << Analysis.getMCInstrInfo()->getName(
                   InstrMeta.Instruction.getOpcode())
            << " ";
-    InstrMeta.Instruction.print(outs());
     outs() << "\n";
-    outs() << "  Protected? "
-           << Verifier.isIndirectInstructionCFIProtected(Address) << "\n";
+
+    if (Analysis.hasLineTableInfo()) {
+      for (const auto &LineKV : Analysis.getLineInfoForAddressRange(Address)) {
+        outs() << "  " << format_hex(LineKV.first, 2) << " = "
+               << LineKV.second.FileName << ":" << LineKV.second.Line << ":"
+               << LineKV.second.Column << " (" << LineKV.second.FunctionName
+               << ")\n";
       }
     }
+  }
+
+  if (ProtectedCount || UnprotectedCount)
+    outs() << formatv(
+        "Unprotected: {0} ({1:P}), Protected: {2} ({3:P})\n", UnprotectedCount,
+        (((double)UnprotectedCount) / (UnprotectedCount + ProtectedCount)),
+        ProtectedCount,
+        (((double)ProtectedCount) / (UnprotectedCount + ProtectedCount)));
+  else
+    outs() << "No indirect CF instructions found.\n";
+}
 
 int main(int argc, char **argv) {
-  cl::ParseCommandLineOptions(argc, argv);
+  cl::ParseCommandLineOptions(
+      argc, argv,
+      "Identifies whether Control Flow Integrity protects all indirect control "
+      "flow instructions in the provided object file, DSO or binary.\nNote: "
+      "Anything statically linked into the provided file *must* be compiled "
+      "with '-g'. This can be relaxed through the '--ignore-dwarf' flag.");
 
   InitializeAllTargetInfos();
   InitializeAllTargetMCs();
   InitializeAllAsmParsers();
   InitializeAllDisassemblers();
 
-  FileAnalysis Verifier = ExitOnErr(FileAnalysis::Create(InputFilename));
-  printIndirectCFInstructions(Verifier);
+  FileAnalysis Analysis = ExitOnErr(FileAnalysis::Create(InputFilename));
+  printIndirectCFInstructions(Analysis);
 
   return EXIT_SUCCESS;
 }