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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] powerpc: Mark .opd section read-only
Date: Wed, 13 Oct 2021 16:43:54 +0200	[thread overview]
Message-ID: <3cd40b682fb6f75bb40947b55ca0bac20cb3f995.1634136222.git.christophe.leroy@csgroup.eu> (raw)

.opd section contains function descriptors used to locate
functions in the kernel. If someone is able to modify a
function descriptor he will be able to run arbitrary
kernel function instead of another.

To avoid that, move .opd section inside read-only memory.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/vmlinux.lds.S | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 40bdefe9caa7..18e42c74abdd 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -143,6 +143,12 @@ SECTIONS
 	SOFT_MASK_TABLE(8)
 	RESTART_TABLE(8)
 
+	.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
+		__start_opd = .;
+		KEEP(*(.opd))
+		__end_opd = .;
+	}
+
 	. = ALIGN(8);
 	__stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) {
 		__start___stf_entry_barrier_fixup = .;
@@ -339,12 +345,6 @@ SECTIONS
 		*(.branch_lt)
 	}
 
-	.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
-		__start_opd = .;
-		KEEP(*(.opd))
-		__end_opd = .;
-	}
-
 	. = ALIGN(256);
 	.got : AT(ADDR(.got) - LOAD_OFFSET) {
 		__toc_start = .;
-- 
2.31.1


WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc: Mark .opd section read-only
Date: Wed, 13 Oct 2021 16:43:54 +0200	[thread overview]
Message-ID: <3cd40b682fb6f75bb40947b55ca0bac20cb3f995.1634136222.git.christophe.leroy@csgroup.eu> (raw)

.opd section contains function descriptors used to locate
functions in the kernel. If someone is able to modify a
function descriptor he will be able to run arbitrary
kernel function instead of another.

To avoid that, move .opd section inside read-only memory.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/vmlinux.lds.S | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 40bdefe9caa7..18e42c74abdd 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -143,6 +143,12 @@ SECTIONS
 	SOFT_MASK_TABLE(8)
 	RESTART_TABLE(8)
 
+	.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
+		__start_opd = .;
+		KEEP(*(.opd))
+		__end_opd = .;
+	}
+
 	. = ALIGN(8);
 	__stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) {
 		__start___stf_entry_barrier_fixup = .;
@@ -339,12 +345,6 @@ SECTIONS
 		*(.branch_lt)
 	}
 
-	.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
-		__start_opd = .;
-		KEEP(*(.opd))
-		__end_opd = .;
-	}
-
 	. = ALIGN(256);
 	.got : AT(ADDR(.got) - LOAD_OFFSET) {
 		__toc_start = .;
-- 
2.31.1


             reply	other threads:[~2021-10-13 14:44 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-13 14:43 Christophe Leroy [this message]
2021-10-13 14:43 ` [PATCH] powerpc: Mark .opd section read-only Christophe Leroy
2021-11-02 10:11 ` Michael Ellerman
2021-11-02 10:11   ` Michael Ellerman

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