From: "Hou Wenlong" <houwenlong.hwl@antgroup.com>
To: linux-kernel@vger.kernel.org
Cc: "Thomas Garnier" <thgarnie@chromium.org>,
"Lai Jiangshan" <jiangshan.ljs@antgroup.com>,
"Kees Cook" <keescook@chromium.org>,
"Hou Wenlong" <houwenlong.hwl@antgroup.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Sami Tolvanen" <samitolvanen@google.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [PATCH RFC 27/43] x86/relocs: Handle PIE relocations
Date: Fri, 28 Apr 2023 17:51:07 +0800 [thread overview]
Message-ID: <d25c7644249355785365914398bdba1ed2c52468.1682673543.git.houwenlong.hwl@antgroup.com> (raw)
In-Reply-To: <cover.1682673542.git.houwenlong.hwl@antgroup.com>
From: Thomas Garnier <thgarnie@chromium.org>
From: Thomas Garnier <thgarnie@chromium.org>
Change the relocation tool to correctly handle relocations generated by
-fPIE option:
- Add relocation for each entry of the .got section given the linker
does not generate R_X86_64_GLOB_DAT on a simple link.
- Ignore R_X86_64_GOTPCREL.
Signed-off-by: Thomas Garnier <thgarnie@chromium.org>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Cc: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Cc: Kees Cook <keescook@chromium.org>
---
arch/x86/tools/relocs.c | 96 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 95 insertions(+), 1 deletion(-)
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 038e9c12fad3..97ac96195232 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -42,6 +42,7 @@ struct section {
Elf32_Word *xsymtab;
Elf_Rel *reltab;
char *strtab;
+ Elf_Addr *got;
};
static struct section *secs;
@@ -308,6 +309,36 @@ static Elf_Sym *sym_lookup(const char *symname)
return 0;
}
+static Elf_Sym *sym_lookup_addr(Elf_Addr addr, const char **name)
+{
+ int i;
+
+ for (i = 0; i < ehdr.e_shnum; i++) {
+ struct section *sec = &secs[i];
+ long nsyms;
+ Elf_Sym *symtab;
+ Elf_Sym *sym;
+
+ if (sec->shdr.sh_type != SHT_SYMTAB)
+ continue;
+
+ nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
+ symtab = sec->symtab;
+
+ for (sym = symtab; --nsyms >= 0; sym++) {
+ if (sym->st_value == addr) {
+ if (name) {
+ *name = sym_name(sec->link->strtab,
+ sym);
+ }
+ return sym;
+ }
+ }
+ }
+ return 0;
+}
+
+
#if BYTE_ORDER == LITTLE_ENDIAN
#define le16_to_cpu(val) (val)
#define le32_to_cpu(val) (val)
@@ -588,6 +619,35 @@ static void read_relocs(FILE *fp)
}
}
+static void read_got(FILE *fp)
+{
+ int i;
+
+ for (i = 0; i < ehdr.e_shnum; i++) {
+ struct section *sec = &secs[i];
+
+ sec->got = NULL;
+ if (sec->shdr.sh_type != SHT_PROGBITS ||
+ strcmp(sec_name(i), ".got")) {
+ continue;
+ }
+ sec->got = malloc(sec->shdr.sh_size);
+ if (!sec->got) {
+ die("malloc of %" FMT " bytes for got failed\n",
+ sec->shdr.sh_size);
+ }
+ if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
+ die("Seek to %" FMT " failed: %s\n",
+ sec->shdr.sh_offset, strerror(errno));
+ }
+ if (fread(sec->got, 1, sec->shdr.sh_size, fp)
+ != sec->shdr.sh_size) {
+ die("Cannot read got: %s\n",
+ strerror(errno));
+ }
+ }
+}
+
static void print_absolute_symbols(void)
{
@@ -718,6 +778,32 @@ static void add_reloc(struct relocs *r, uint32_t offset)
r->offset[r->count++] = offset;
}
+/*
+ * The linker does not generate relocations for the GOT for the kernel.
+ * If a GOT is found, simulate the relocations that should have been included.
+ */
+static void walk_got_table(int (*process)(struct section *sec, Elf_Rel *rel,
+ Elf_Sym *sym, const char *symname),
+ struct section *sec)
+{
+ int i;
+ Elf_Addr entry;
+ Elf_Sym *sym;
+ const char *symname;
+ Elf_Rel rel;
+
+ for (i = 0; i < sec->shdr.sh_size/sizeof(Elf_Addr); i++) {
+ entry = sec->got[i];
+ sym = sym_lookup_addr(entry, &symname);
+ if (!sym)
+ die("Could not found got symbol for entry %d\n", i);
+ rel.r_offset = sec->shdr.sh_addr + i * sizeof(Elf_Addr);
+ rel.r_info = ELF_BITS == 64 ? R_X86_64_GLOB_DAT
+ : R_386_GLOB_DAT;
+ process(sec, &rel, sym, symname);
+ }
+}
+
static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
Elf_Sym *sym, const char *symname))
{
@@ -731,6 +817,8 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
struct section *sec = &secs[i];
if (sec->shdr.sh_type != SHT_REL_TYPE) {
+ if (sec->got)
+ walk_got_table(process, sec);
continue;
}
sec_symtab = sec->link;
@@ -842,6 +930,7 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
offset += per_cpu_load_addr;
switch (r_type) {
+ case R_X86_64_GOTPCREL:
case R_X86_64_NONE:
/* NONE can be ignored. */
break;
@@ -905,7 +994,7 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
* the relocations are processed.
* Make sure that the offset will fit.
*/
- if ((int32_t)offset != (int64_t)offset)
+ if (r_type != R_X86_64_64 && (int32_t)offset != (int64_t)offset)
die("Relocation offset doesn't fit in 32 bits\n");
if (r_type == R_X86_64_64)
@@ -914,6 +1003,10 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
add_reloc(&relocs32, offset);
break;
+ case R_X86_64_GLOB_DAT:
+ add_reloc(&relocs64, offset);
+ break;
+
default:
die("Unsupported relocation type: %s (%d)\n",
rel_type(r_type), r_type);
@@ -1188,6 +1281,7 @@ void process(FILE *fp, int use_real_mode, int as_text,
read_strtabs(fp);
read_symtabs(fp);
read_relocs(fp);
+ read_got(fp);
if (ELF_BITS == 64)
percpu_init();
if (show_absolute_syms) {
--
2.31.1
next prev parent reply other threads:[~2023-04-28 9:57 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-28 9:50 [PATCH RFC 00/43] x86/pie: Make kernel image's virtual address flexible Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 01/43] x86/crypto: Adapt assembly for PIE support Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 02/43] x86: Add macro to get symbol address " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 03/43] x86: relocate_kernel - Adapt assembly " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 04/43] x86/entry/64: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 05/43] x86: pm-trace: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 06/43] x86/CPU: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 07/43] x86/acpi: " Hou Wenlong
2023-04-28 11:32 ` Rafael J. Wysocki
2023-04-28 9:50 ` [PATCH RFC 08/43] x86/boot/64: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 09/43] x86/power/64: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 10/43] x86/alternatives: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 11/43] x86/irq: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 12/43] x86,rethook: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 13/43] x86/paravirt: Use relative reference for original instruction Hou Wenlong
2023-06-01 9:29 ` Juergen Gross
2023-06-05 6:40 ` Nadav Amit
2023-06-06 11:35 ` Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 14/43] x86/Kconfig: Introduce new Kconfig for PIE kernel building Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 15/43] x86/PVH: Use fixed_percpu_data to set up GS base Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 16/43] x86-64: Use per-cpu stack canary if supported by compiler Hou Wenlong
2023-05-01 17:27 ` Nick Desaulniers
2023-05-05 6:14 ` Hou Wenlong
2023-05-05 18:02 ` Nick Desaulniers
2023-05-05 19:06 ` Fangrui Song
2023-05-08 8:06 ` Hou Wenlong
2023-05-04 10:31 ` Juergen Gross
2023-05-05 3:09 ` Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 17/43] x86/pie: Enable stack protector only if per-cpu stack canary is supported Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 18/43] x86/percpu: Use PC-relative addressing for percpu variable references Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 19/43] x86/tools: Explicitly include autoconf.h for hostprogs Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 20/43] x86/percpu: Adapt percpu references relocation for PIE support Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 21/43] x86/ftrace: Adapt assembly " Hou Wenlong
2023-04-28 13:37 ` Steven Rostedt
2023-04-29 3:43 ` Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 22/43] x86/ftrace: Adapt ftrace nop patching " Hou Wenlong
2023-04-28 13:44 ` Steven Rostedt
2023-04-29 3:38 ` Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 23/43] x86/pie: Force hidden visibility for all symbol references Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 24/43] x86/boot/compressed: Adapt sed command to generate voffset.h when PIE is enabled Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 25/43] x86/mm: Make the x86 GOT read-only Hou Wenlong
2023-04-30 14:23 ` Ard Biesheuvel
2023-05-08 11:40 ` Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 26/43] x86/pie: Add .data.rel.* sections into link script Hou Wenlong
2023-04-28 9:51 ` Hou Wenlong [this message]
2023-04-28 9:51 ` [PATCH RFC 28/43] KVM: x86: Adapt assembly for PIE support Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 29/43] x86/PVH: Adapt PVH booting " Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 30/43] x86/bpf: Adapt BPF_CALL JIT codegen " Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 31/43] x86/modules: Adapt module loading " Hou Wenlong
2023-04-28 19:29 ` Ard Biesheuvel
2023-05-08 8:32 ` Hou Wenlong
2023-05-08 9:16 ` Ard Biesheuvel
2023-05-08 11:40 ` Hou Wenlong
2023-05-08 17:47 ` Ard Biesheuvel
2023-05-09 9:42 ` Hou Wenlong
2023-05-09 9:52 ` Ard Biesheuvel
2023-05-09 12:35 ` Hou Wenlong
2023-05-10 7:09 ` Hou Wenlong
2023-05-10 8:15 ` Ard Biesheuvel
2023-04-28 9:51 ` [PATCH RFC 32/43] x86/boot/64: Use data relocation to get absloute address when PIE is enabled Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 33/43] objtool: Add validation for x86 PIE support Hou Wenlong
2023-04-28 10:28 ` Christophe Leroy
2023-04-28 11:43 ` Peter Zijlstra
2023-04-29 4:04 ` Hou Wenlong
2023-04-29 3:52 ` Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 34/43] objtool: Adapt indirect call of __fentry__() for " Hou Wenlong
2023-04-28 15:18 ` Peter Zijlstra
2023-04-28 9:51 ` [PATCH RFC 35/43] x86/pie: Build the kernel as PIE Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 36/43] x86/vsyscall: Don't use set_fixmap() to map vsyscall page Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 37/43] x86/xen: Pin up to VSYSCALL_ADDR when vsyscall page is out of fixmap area Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 38/43] x86/fixmap: Move vsyscall page " Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 39/43] x86/fixmap: Unify FIXADDR_TOP Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 40/43] x86/boot: Fill kernel image puds dynamically Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 41/43] x86/mm: Sort address_markers array when X86 PIE is enabled Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 42/43] x86/pie: Allow kernel image to be relocated in top 512G Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 43/43] x86/boot: Extend relocate range for PIE kernel image Hou Wenlong
2023-04-28 15:22 ` [PATCH RFC 00/43] x86/pie: Make kernel image's virtual address flexible Peter Zijlstra
2023-05-06 7:19 ` Hou Wenlong
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