svn commit: r356053 - in head/sys: arm/arm arm64/arm64 i386/i386 kern powerpc/powerpc riscv/riscv sparc64/sparc64 sys
Brandon Bergren
bdragon at FreeBSD.org
Tue Dec 24 15:56:26 UTC 2019
Author: bdragon
Date: Tue Dec 24 15:56:24 2019
New Revision: 356053
URL: https://svnweb.freebsd.org/changeset/base/356053
Log:
[PowerPC] Implement Secure-PLT jump table processing for ppc32.
Due to clang and LLD's tendency to use a PLT for builtins, and as they
don't have full support for EABI, we sometimes have to deal with a PLT in
.ko files in a clang-built kernel.
As such, augment the in-kernel linker to support jump table processing.
As there is no particular reason to support lazy binding in kernel modules,
only implement Secure-PLT immediate binding.
As part of these changes, add elf_cpu_parse_dynamic() to the MD API of the
in-kernel linker (except on platforms that use raw object files.)
The new function will allow MD code to act on MD tags in _DYNAMIC.
Use this new function in the PowerPC MD code to ensure BSS-PLT modules using
PLT will be rejected during insertion, and to poison the runtime resolver to
ensure we get a clear panic reason if a call is made to the resolver.
Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D22608
Modified:
head/sys/arm/arm/elf_machdep.c
head/sys/arm64/arm64/elf_machdep.c
head/sys/i386/i386/elf_machdep.c
head/sys/kern/link_elf.c
head/sys/powerpc/powerpc/elf32_machdep.c
head/sys/powerpc/powerpc/elf64_machdep.c
head/sys/riscv/riscv/elf_machdep.c
head/sys/sparc64/sparc64/elf_machdep.c
head/sys/sys/linker.h
Modified: head/sys/arm/arm/elf_machdep.c
==============================================================================
--- head/sys/arm/arm/elf_machdep.c Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/arm/arm/elf_machdep.c Tue Dec 24 15:56:24 2019 (r356053)
@@ -321,6 +321,13 @@ elf_cpu_load_file(linker_file_t lf)
}
int
+elf_cpu_parse_dynamic(linker_file_t lf __unused, Elf_Dyn *dynamic __unused)
+{
+
+ return (0);
+}
+
+int
elf_cpu_unload_file(linker_file_t lf)
{
Modified: head/sys/arm64/arm64/elf_machdep.c
==============================================================================
--- head/sys/arm64/arm64/elf_machdep.c Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/arm64/arm64/elf_machdep.c Tue Dec 24 15:56:24 2019 (r356053)
@@ -216,3 +216,10 @@ elf_cpu_unload_file(linker_file_t lf __unused)
return (0);
}
+
+int
+elf_cpu_parse_dynamic(linker_file_t lf __unused, Elf_Dyn *dynamic __unused)
+{
+
+ return (0);
+}
Modified: head/sys/i386/i386/elf_machdep.c
==============================================================================
--- head/sys/i386/i386/elf_machdep.c Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/i386/i386/elf_machdep.c Tue Dec 24 15:56:24 2019 (r356053)
@@ -295,3 +295,10 @@ elf_cpu_unload_file(linker_file_t lf __unused)
return (0);
}
+
+int
+elf_cpu_parse_dynamic(linker_file_t lf __unused, Elf_Dyn *dynamic __unused)
+{
+
+ return (0);
+}
Modified: head/sys/kern/link_elf.c
==============================================================================
--- head/sys/kern/link_elf.c Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/kern/link_elf.c Tue Dec 24 15:56:24 2019 (r356053)
@@ -611,7 +611,7 @@ parse_dynamic(elf_file_t ef)
ef->ddbstrtab = ef->strtab;
ef->ddbstrcnt = ef->strsz;
- return (0);
+ return elf_cpu_parse_dynamic(&ef->lf, ef->dynamic);
}
#define LS_PADDING 0x90909090
Modified: head/sys/powerpc/powerpc/elf32_machdep.c
==============================================================================
--- head/sys/powerpc/powerpc/elf32_machdep.c Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/powerpc/powerpc/elf32_machdep.c Tue Dec 24 15:56:24 2019 (r356053)
@@ -63,6 +63,7 @@
extern const char *freebsd32_syscallnames[];
static void ppc32_fixlimit(struct rlimit *rl, int which);
+static void ppc32_runtime_resolve(void);
static SYSCTL_NODE(_compat, OID_AUTO, ppc32, CTLFLAG_RW, 0, "32-bit mode");
@@ -296,6 +297,20 @@ elf_reloc_internal(linker_file_t lf, Elf_Addr relocbas
*where = elf_relocaddr(lf, relocbase + addend);
break;
+ case R_PPC_JMP_SLOT: /* PLT jump slot entry */
+ /*
+ * We currently only support Secure-PLT jump slots.
+ * Given that we reject BSS-PLT modules during load, we
+ * don't need to check again.
+ * The method we are using here is equivilent to
+ * LD_BIND_NOW.
+ */
+ error = lookup(lf, symidx, 1, &addr);
+ if (error != 0)
+ return -1;
+ *where = elf_relocaddr(lf, addr + addend);
+ break;
+
default:
printf("kldload: unexpected relocation type %d\n",
(int) rtype);
@@ -356,6 +371,7 @@ elf_reloc_local(linker_file_t lf, Elf_Addr relocbase,
int
elf_cpu_load_file(linker_file_t lf)
{
+
/* Only sync the cache for non-kernel modules */
if (lf->id != 1)
__syncicache(lf->address, lf->size);
@@ -366,6 +382,47 @@ int
elf_cpu_unload_file(linker_file_t lf __unused)
{
+ return (0);
+}
+
+static void
+ppc32_runtime_resolve()
+{
+
+ /*
+ * Since we don't support lazy binding, panic immediately if anyone
+ * manages to call the runtime resolver.
+ */
+ panic("kldload: Runtime resolver was called unexpectedly!");
+}
+
+int
+elf_cpu_parse_dynamic(linker_file_t lf, Elf_Dyn *dynamic)
+{
+ Elf_Dyn *dp;
+ bool has_plt = false;
+ bool secure_plt = false;
+ Elf_Addr *got;
+
+ for (dp = dynamic; dp->d_tag != DT_NULL; dp++) {
+ switch (dp->d_tag) {
+ case DT_PPC_GOT:
+ secure_plt = true;
+ got = (Elf_Addr *)(lf->address + dp->d_un.d_ptr);
+ /* Install runtime resolver canary. */
+ got[1] = (Elf_Addr)ppc32_runtime_resolve;
+ got[2] = (Elf_Addr)0;
+ break;
+ case DT_PLTGOT:
+ has_plt = true;
+ break;
+ }
+ }
+
+ if (has_plt && !secure_plt) {
+ printf("kldload: BSS-PLT modules are not supported.\n");
+ return (-1);
+ }
return (0);
}
#endif
Modified: head/sys/powerpc/powerpc/elf64_machdep.c
==============================================================================
--- head/sys/powerpc/powerpc/elf64_machdep.c Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/powerpc/powerpc/elf64_machdep.c Tue Dec 24 15:56:24 2019 (r356053)
@@ -410,3 +410,10 @@ elf_cpu_unload_file(linker_file_t lf __unused)
return (0);
}
+
+int
+elf_cpu_parse_dynamic(linker_file_t lf __unused, Elf_Dyn *dynamic __unused)
+{
+
+ return (0);
+}
Modified: head/sys/riscv/riscv/elf_machdep.c
==============================================================================
--- head/sys/riscv/riscv/elf_machdep.c Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/riscv/riscv/elf_machdep.c Tue Dec 24 15:56:24 2019 (r356053)
@@ -504,3 +504,10 @@ elf_cpu_unload_file(linker_file_t lf __unused)
return (0);
}
+
+int
+elf_cpu_parse_dynamic(linker_file_t lf __unused, Elf_Dyn *dynamic __unused)
+{
+
+ return (0);
+}
Modified: head/sys/sparc64/sparc64/elf_machdep.c
==============================================================================
--- head/sys/sparc64/sparc64/elf_machdep.c Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/sparc64/sparc64/elf_machdep.c Tue Dec 24 15:56:24 2019 (r356053)
@@ -429,3 +429,10 @@ elf_cpu_unload_file(linker_file_t lf __unused)
return (0);
}
+
+int
+elf_cpu_parse_dynamic(linker_file_t lf __unused, Elf_Dyn *dynamic __unused)
+{
+
+ return (0);
+}
Modified: head/sys/sys/linker.h
==============================================================================
--- head/sys/sys/linker.h Tue Dec 24 14:50:17 2019 (r356052)
+++ head/sys/sys/linker.h Tue Dec 24 15:56:24 2019 (r356053)
@@ -305,6 +305,10 @@ int linker_ctf_get(linker_file_t, linker_ctf_t *);
int elf_cpu_load_file(linker_file_t);
int elf_cpu_unload_file(linker_file_t);
+/* amd64 and mips use objects instead of shared libraries */
+#if !defined(__amd64__) && !defined(__mips__)
+int elf_cpu_parse_dynamic(linker_file_t, Elf_Dyn *);
+#endif
/* values for type */
#define ELF_RELOC_REL 1
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