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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Marc Zyngier <maz@kernel.org>,
	kvmarm@lists.cs.columbia.edu, linux-hardening@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Subject: [RFC PATCH 09/12] arm64: mm: remap kernel page tables read-only at end of init
Date: Wed, 26 Jan 2022 18:30:08 +0100	[thread overview]
Message-ID: <20220126173011.3476262-10-ardb@kernel.org> (raw)
In-Reply-To: <20220126173011.3476262-1-ardb@kernel.org>

Now that all the handling is in place to deal with read-only page tables
at runtime, do a pass over the kernel page tables at boot to remap all
the page table pages read-only that were allocated early.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/mm/mmu.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 971501535757..b1212f6d48f2 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -559,8 +559,23 @@ static void __init map_mem(pgd_t *pgdp)
 	memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
 }
 
+static void mark_pgtables_ro(const pmd_t *pmdp, int level, int num_entries)
+{
+	while (num_entries--) {
+		if (pmd_valid(*pmdp) && pmd_table(*pmdp)) {
+			pmd_t *next = __va(__pmd_to_phys(*pmdp));
+
+			if (level < 2)
+				mark_pgtables_ro(next, level + 1, PTRS_PER_PMD);
+			set_pgtable_ro(next);
+		}
+		pmdp++;
+	}
+}
+
 void mark_rodata_ro(void)
 {
+	int pgd_level = 4 - CONFIG_PGTABLE_LEVELS;
 	unsigned long section_size;
 
 	/*
@@ -571,6 +586,11 @@ void mark_rodata_ro(void)
 	update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
 			    section_size, PAGE_KERNEL_RO);
 
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+	mark_pgtables_ro((pmd_t *)&tramp_pg_dir, pgd_level, PTRS_PER_PGD);
+#endif
+	mark_pgtables_ro((pmd_t *)&swapper_pg_dir, pgd_level, PTRS_PER_PGD);
+
 	debug_checkwx();
 }
 
-- 
2.30.2

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu, linux-hardening@vger.kernel.org,
	Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
	Marc Zyngier <maz@kernel.org>, Fuad Tabba <tabba@google.com>,
	Quentin Perret <qperret@google.com>,
	Mark Rutland <mark.rutland@arm.com>,
	James Morse <james.morse@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>
Subject: [RFC PATCH 09/12] arm64: mm: remap kernel page tables read-only at end of init
Date: Wed, 26 Jan 2022 18:30:08 +0100	[thread overview]
Message-ID: <20220126173011.3476262-10-ardb@kernel.org> (raw)
In-Reply-To: <20220126173011.3476262-1-ardb@kernel.org>

Now that all the handling is in place to deal with read-only page tables
at runtime, do a pass over the kernel page tables at boot to remap all
the page table pages read-only that were allocated early.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/mm/mmu.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 971501535757..b1212f6d48f2 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -559,8 +559,23 @@ static void __init map_mem(pgd_t *pgdp)
 	memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
 }
 
+static void mark_pgtables_ro(const pmd_t *pmdp, int level, int num_entries)
+{
+	while (num_entries--) {
+		if (pmd_valid(*pmdp) && pmd_table(*pmdp)) {
+			pmd_t *next = __va(__pmd_to_phys(*pmdp));
+
+			if (level < 2)
+				mark_pgtables_ro(next, level + 1, PTRS_PER_PMD);
+			set_pgtable_ro(next);
+		}
+		pmdp++;
+	}
+}
+
 void mark_rodata_ro(void)
 {
+	int pgd_level = 4 - CONFIG_PGTABLE_LEVELS;
 	unsigned long section_size;
 
 	/*
@@ -571,6 +586,11 @@ void mark_rodata_ro(void)
 	update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
 			    section_size, PAGE_KERNEL_RO);
 
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+	mark_pgtables_ro((pmd_t *)&tramp_pg_dir, pgd_level, PTRS_PER_PGD);
+#endif
+	mark_pgtables_ro((pmd_t *)&swapper_pg_dir, pgd_level, PTRS_PER_PGD);
+
 	debug_checkwx();
 }
 
-- 
2.30.2


WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu, linux-hardening@vger.kernel.org,
	Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
	Marc Zyngier <maz@kernel.org>, Fuad Tabba <tabba@google.com>,
	Quentin Perret <qperret@google.com>,
	Mark Rutland <mark.rutland@arm.com>,
	James Morse <james.morse@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>
Subject: [RFC PATCH 09/12] arm64: mm: remap kernel page tables read-only at end of init
Date: Wed, 26 Jan 2022 18:30:08 +0100	[thread overview]
Message-ID: <20220126173011.3476262-10-ardb@kernel.org> (raw)
In-Reply-To: <20220126173011.3476262-1-ardb@kernel.org>

Now that all the handling is in place to deal with read-only page tables
at runtime, do a pass over the kernel page tables at boot to remap all
the page table pages read-only that were allocated early.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/mm/mmu.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 971501535757..b1212f6d48f2 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -559,8 +559,23 @@ static void __init map_mem(pgd_t *pgdp)
 	memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
 }
 
+static void mark_pgtables_ro(const pmd_t *pmdp, int level, int num_entries)
+{
+	while (num_entries--) {
+		if (pmd_valid(*pmdp) && pmd_table(*pmdp)) {
+			pmd_t *next = __va(__pmd_to_phys(*pmdp));
+
+			if (level < 2)
+				mark_pgtables_ro(next, level + 1, PTRS_PER_PMD);
+			set_pgtable_ro(next);
+		}
+		pmdp++;
+	}
+}
+
 void mark_rodata_ro(void)
 {
+	int pgd_level = 4 - CONFIG_PGTABLE_LEVELS;
 	unsigned long section_size;
 
 	/*
@@ -571,6 +586,11 @@ void mark_rodata_ro(void)
 	update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
 			    section_size, PAGE_KERNEL_RO);
 
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+	mark_pgtables_ro((pmd_t *)&tramp_pg_dir, pgd_level, PTRS_PER_PGD);
+#endif
+	mark_pgtables_ro((pmd_t *)&swapper_pg_dir, pgd_level, PTRS_PER_PGD);
+
 	debug_checkwx();
 }
 
-- 
2.30.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-01-26 17:30 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-26 17:29 [RFC PATCH 00/12] arm64: implement read-only page tables Ard Biesheuvel
2022-01-26 17:29 ` Ard Biesheuvel
2022-01-26 17:29 ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 01/12] asm-generic/pgalloc: allow arch to override PMD alloc/free routines Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 02/12] arm64: mm: add helpers to remap page tables read-only/read-write Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 03/12] arm64: mm: use a fixmap slot for user page table modifications Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-28 16:08   ` Steven Price
2022-01-28 16:08     ` Steven Price
2022-01-28 16:08     ` Steven Price
2022-01-26 17:30 ` [RFC PATCH 04/12] arm64: mm: remap PGD pages r/o in the linear region after allocation Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 05/12] arm64: mm: remap PUD pages r/o in linear region Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 06/12] arm64: mm: remap PMD " Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 07/12] arm64: mm: remap PTE level user page tables r/o in the " Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 08/12] arm64: mm: remap kernel PTE level " Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` Ard Biesheuvel [this message]
2022-01-26 17:30   ` [RFC PATCH 09/12] arm64: mm: remap kernel page tables read-only at end of init Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 10/12] mm: add default definition of p4d_index() Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 11/12] arm64: efi: use set_pte_at() not set_pte() in order to pass mm pointer Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 12/12] arm64: hugetlb: use set_pte_at() not set_pte() to provide " Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel
2022-01-26 17:30   ` Ard Biesheuvel

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