From: Josh Poimboeuf <jpoimboe@redhat.com>
To: live-patching@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Jessica Yu <jeyu@kernel.org>,
linux-s390@vger.kernel.org, heiko.carstens@de.ibm.com
Subject: [PATCH 4/7] s390/module: Use s390_kernel_write() for relocations
Date: Tue, 14 Apr 2020 11:28:40 -0500 [thread overview]
Message-ID: <e7f2ad87cf83dcdaa7b69b4e37c11fa355bdfe78.1586881704.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <cover.1586881704.git.jpoimboe@redhat.com>
From: Peter Zijlstra <peterz@infradead.org>
Instead of playing games with module_{dis,en}able_ro(), use existing
text poking mechanisms to apply relocations after module loading.
So far only x86, s390 and Power have HAVE_LIVEPATCH but only the first
two also have STRICT_MODULE_RWX.
This will allow removal of the last module_disable_ro() usage in
livepatch. The ultimate goal is to completely disallow making
executable mappings writable.
[ jpoimboe: Split up patches. Use mod state to determine whether
memcpy() can be used. ]
Cc: linux-s390@vger.kernel.org
Cc: heiko.carstens@de.ibm.com
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/s390/kernel/module.c | 106 ++++++++++++++++++++++----------------
1 file changed, 61 insertions(+), 45 deletions(-)
diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c
index ba8f19bb438b..e85e378f876e 100644
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -174,7 +174,8 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
}
static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
- int sign, int bits, int shift)
+ int sign, int bits, int shift,
+ void (*write)(void *dest, const void *src, size_t len))
{
unsigned long umax;
long min, max;
@@ -194,26 +195,29 @@ static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
return -ENOEXEC;
}
- if (bits == 8)
- *(unsigned char *) loc = val;
- else if (bits == 12)
- *(unsigned short *) loc = (val & 0xfff) |
+ if (bits == 8) {
+ write(loc, &val, 1);
+ } else if (bits == 12) {
+ unsigned short tmp = (val & 0xfff) |
(*(unsigned short *) loc & 0xf000);
- else if (bits == 16)
- *(unsigned short *) loc = val;
- else if (bits == 20)
- *(unsigned int *) loc = (val & 0xfff) << 16 |
- (val & 0xff000) >> 4 |
- (*(unsigned int *) loc & 0xf00000ff);
- else if (bits == 32)
- *(unsigned int *) loc = val;
- else if (bits == 64)
- *(unsigned long *) loc = val;
+ write(loc, &tmp, 2);
+ } else if (bits == 16) {
+ write(loc, &val, 2);
+ } else if (bits == 20) {
+ unsigned int tmp = (val & 0xfff) << 16 |
+ (val & 0xff000) >> 4 | (*(unsigned int *) loc & 0xf00000ff);
+ write(loc, &tmp, 4);
+ } else if (bits == 32) {
+ write(loc, &val, 4);
+ } else if (bits == 64) {
+ write(loc, &val, 8);
+ }
return 0;
}
static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
- const char *strtab, struct module *me)
+ const char *strtab, struct module *me,
+ void (*write)(void *dest, const void *src, size_t len))
{
struct mod_arch_syminfo *info;
Elf_Addr loc, val;
@@ -241,17 +245,17 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
case R_390_64: /* Direct 64 bit. */
val += rela->r_addend;
if (r_type == R_390_8)
- rc = apply_rela_bits(loc, val, 0, 8, 0);
+ rc = apply_rela_bits(loc, val, 0, 8, 0, write);
else if (r_type == R_390_12)
- rc = apply_rela_bits(loc, val, 0, 12, 0);
+ rc = apply_rela_bits(loc, val, 0, 12, 0, write);
else if (r_type == R_390_16)
- rc = apply_rela_bits(loc, val, 0, 16, 0);
+ rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_20)
- rc = apply_rela_bits(loc, val, 1, 20, 0);
+ rc = apply_rela_bits(loc, val, 1, 20, 0, write);
else if (r_type == R_390_32)
- rc = apply_rela_bits(loc, val, 0, 32, 0);
+ rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_64)
- rc = apply_rela_bits(loc, val, 0, 64, 0);
+ rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break;
case R_390_PC16: /* PC relative 16 bit. */
case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
@@ -260,15 +264,15 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
case R_390_PC64: /* PC relative 64 bit. */
val += rela->r_addend - loc;
if (r_type == R_390_PC16)
- rc = apply_rela_bits(loc, val, 1, 16, 0);
+ rc = apply_rela_bits(loc, val, 1, 16, 0, write);
else if (r_type == R_390_PC16DBL)
- rc = apply_rela_bits(loc, val, 1, 16, 1);
+ rc = apply_rela_bits(loc, val, 1, 16, 1, write);
else if (r_type == R_390_PC32DBL)
- rc = apply_rela_bits(loc, val, 1, 32, 1);
+ rc = apply_rela_bits(loc, val, 1, 32, 1, write);
else if (r_type == R_390_PC32)
- rc = apply_rela_bits(loc, val, 1, 32, 0);
+ rc = apply_rela_bits(loc, val, 1, 32, 0, write);
else if (r_type == R_390_PC64)
- rc = apply_rela_bits(loc, val, 1, 64, 0);
+ rc = apply_rela_bits(loc, val, 1, 64, 0, write);
break;
case R_390_GOT12: /* 12 bit GOT offset. */
case R_390_GOT16: /* 16 bit GOT offset. */
@@ -293,23 +297,23 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
val = info->got_offset + rela->r_addend;
if (r_type == R_390_GOT12 ||
r_type == R_390_GOTPLT12)
- rc = apply_rela_bits(loc, val, 0, 12, 0);
+ rc = apply_rela_bits(loc, val, 0, 12, 0, write);
else if (r_type == R_390_GOT16 ||
r_type == R_390_GOTPLT16)
- rc = apply_rela_bits(loc, val, 0, 16, 0);
+ rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_GOT20 ||
r_type == R_390_GOTPLT20)
- rc = apply_rela_bits(loc, val, 1, 20, 0);
+ rc = apply_rela_bits(loc, val, 1, 20, 0, write);
else if (r_type == R_390_GOT32 ||
r_type == R_390_GOTPLT32)
- rc = apply_rela_bits(loc, val, 0, 32, 0);
+ rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_GOT64 ||
r_type == R_390_GOTPLT64)
- rc = apply_rela_bits(loc, val, 0, 64, 0);
+ rc = apply_rela_bits(loc, val, 0, 64, 0, write);
else if (r_type == R_390_GOTENT ||
r_type == R_390_GOTPLTENT) {
val += (Elf_Addr) me->core_layout.base - loc;
- rc = apply_rela_bits(loc, val, 1, 32, 1);
+ rc = apply_rela_bits(loc, val, 1, 32, 1, write);
}
break;
case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
@@ -357,17 +361,17 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
val += rela->r_addend - loc;
}
if (r_type == R_390_PLT16DBL)
- rc = apply_rela_bits(loc, val, 1, 16, 1);
+ rc = apply_rela_bits(loc, val, 1, 16, 1, write);
else if (r_type == R_390_PLTOFF16)
- rc = apply_rela_bits(loc, val, 0, 16, 0);
+ rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_PLT32DBL)
- rc = apply_rela_bits(loc, val, 1, 32, 1);
+ rc = apply_rela_bits(loc, val, 1, 32, 1, write);
else if (r_type == R_390_PLT32 ||
r_type == R_390_PLTOFF32)
- rc = apply_rela_bits(loc, val, 0, 32, 0);
+ rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_PLT64 ||
r_type == R_390_PLTOFF64)
- rc = apply_rela_bits(loc, val, 0, 64, 0);
+ rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break;
case R_390_GOTOFF16: /* 16 bit offset to GOT. */
case R_390_GOTOFF32: /* 32 bit offset to GOT. */
@@ -375,20 +379,20 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
val = val + rela->r_addend -
((Elf_Addr) me->core_layout.base + me->arch.got_offset);
if (r_type == R_390_GOTOFF16)
- rc = apply_rela_bits(loc, val, 0, 16, 0);
+ rc = apply_rela_bits(loc, val, 0, 16, 0, write);
else if (r_type == R_390_GOTOFF32)
- rc = apply_rela_bits(loc, val, 0, 32, 0);
+ rc = apply_rela_bits(loc, val, 0, 32, 0, write);
else if (r_type == R_390_GOTOFF64)
- rc = apply_rela_bits(loc, val, 0, 64, 0);
+ rc = apply_rela_bits(loc, val, 0, 64, 0, write);
break;
case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */
val = (Elf_Addr) me->core_layout.base + me->arch.got_offset +
rela->r_addend - loc;
if (r_type == R_390_GOTPC)
- rc = apply_rela_bits(loc, val, 1, 32, 0);
+ rc = apply_rela_bits(loc, val, 1, 32, 0, write);
else if (r_type == R_390_GOTPCDBL)
- rc = apply_rela_bits(loc, val, 1, 32, 1);
+ rc = apply_rela_bits(loc, val, 1, 32, 1, write);
break;
case R_390_COPY:
case R_390_GLOB_DAT: /* Create GOT entry. */
@@ -412,9 +416,10 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
return 0;
}
-int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
+static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec,
- struct module *me)
+ struct module *me,
+ void (*write)(void *dest, const void *src, size_t len))
{
Elf_Addr base;
Elf_Sym *symtab;
@@ -437,6 +442,17 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
return 0;
}
+int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
+ unsigned int symindex, unsigned int relsec,
+ struct module *me)
+{
+ int ret;
+ bool early = me->state == MODULE_STATE_UNFORMED;
+
+ return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
+ early ? memcpy : s390_kernel_write);
+}
+
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
--
2.21.1
next prev parent reply other threads:[~2020-04-14 16:32 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 16:28 [PATCH 0/7] livepatch,module: Remove .klp.arch and module_disable_ro() Josh Poimboeuf
2020-04-14 16:28 ` [PATCH 1/7] livepatch: Apply vmlinux-specific KLP relocations early Josh Poimboeuf
2020-04-14 17:44 ` Peter Zijlstra
2020-04-14 18:01 ` Josh Poimboeuf
2020-04-14 19:31 ` Josh Poimboeuf
2020-04-15 14:30 ` Miroslav Benes
2020-04-15 16:29 ` Josh Poimboeuf
2020-04-15 14:34 ` Miroslav Benes
2020-04-15 16:30 ` Josh Poimboeuf
2020-04-14 16:28 ` [PATCH 2/7] livepatch: Remove .klp.arch Josh Poimboeuf
2020-04-15 15:18 ` Jessica Yu
2020-04-14 16:28 ` [PATCH 3/7] livepatch: Prevent module-specific KLP rela sections from referencing vmlinux symbols Josh Poimboeuf
2020-04-14 16:28 ` Josh Poimboeuf [this message]
2020-04-16 8:56 ` [PATCH 4/7] s390/module: Use s390_kernel_write() for relocations Miroslav Benes
2020-04-16 12:06 ` Josh Poimboeuf
2020-04-16 13:16 ` Josh Poimboeuf
2020-04-17 1:37 ` Josh Poimboeuf
2020-04-14 16:28 ` [PATCH 5/7] x86/module: Use text_poke() " Josh Poimboeuf
2020-04-14 16:28 ` [PATCH 6/7] livepatch: Remove module_disable_ro() usage Josh Poimboeuf
2020-04-15 15:02 ` Jessica Yu
2020-04-15 16:33 ` Josh Poimboeuf
2020-04-16 9:28 ` Miroslav Benes
2020-04-16 12:10 ` Josh Poimboeuf
2020-04-14 16:28 ` [PATCH 7/7] module: Remove module_disable_ro() Josh Poimboeuf
2020-04-14 18:27 ` [PATCH 0/7] livepatch,module: Remove .klp.arch and module_disable_ro() Peter Zijlstra
2020-04-14 19:08 ` Josh Poimboeuf
2020-04-15 14:24 ` Peter Zijlstra
2020-04-15 16:17 ` Josh Poimboeuf
2020-04-16 15:31 ` Jessica Yu
2020-04-16 15:45 ` Josh Poimboeuf
2020-04-17 8:27 ` Miroslav Benes
2020-04-17 8:50 ` Jessica Yu
2020-04-16 9:45 ` Miroslav Benes
2020-04-16 12:20 ` Josh Poimboeuf
2020-04-17 9:08 ` Miroslav Benes
2020-04-15 0:57 ` Joe Lawrence
2020-04-15 1:31 ` Josh Poimboeuf
2020-04-15 1:37 ` Joe Lawrence
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