From 98a23609b10364a51a1bb3688f8dd1cd1aa94a9a Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 8 Jun 2020 21:34:50 -0700 Subject: maccess: always use strict semantics for probe_kernel_read Except for historical confusion in the kprobes/uprobes and bpf tracers, which has been fixed now, there is no good reason to ever allow user memory accesses from probe_kernel_read. Switch probe_kernel_read to only read from kernel memory. [akpm@linux-foundation.org: update it for "mm, dump_page(): do not crash with invalid mapping pointer"] Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20200521152301.2587579-17-hch@lst.de Signed-off-by: Linus Torvalds --- arch/parisc/lib/memcpy.c | 2 +- arch/um/kernel/maccess.c | 2 +- arch/x86/mm/maccess.c | 9 ++------- 3 files changed, 4 insertions(+), 9 deletions(-) (limited to 'arch') diff --git a/arch/parisc/lib/memcpy.c b/arch/parisc/lib/memcpy.c index 5b75c35d1da0..94a9fe2702c2 100644 --- a/arch/parisc/lib/memcpy.c +++ b/arch/parisc/lib/memcpy.c @@ -57,7 +57,7 @@ void * memcpy(void * dst,const void *src, size_t count) EXPORT_SYMBOL(raw_copy_in_user); EXPORT_SYMBOL(memcpy); -bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict) +bool probe_kernel_read_allowed(const void *unsafe_src, size_t size) { if ((unsigned long)unsafe_src < PAGE_SIZE) return false; diff --git a/arch/um/kernel/maccess.c b/arch/um/kernel/maccess.c index ad2c538ce497..e929c0966696 100644 --- a/arch/um/kernel/maccess.c +++ b/arch/um/kernel/maccess.c @@ -7,7 +7,7 @@ #include #include -bool probe_kernel_read_allowed(const void *src, size_t size, bool strict) +bool probe_kernel_read_allowed(const void *src, size_t size) { void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE); diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c index 86000c1150e8..e1d7d7477c22 100644 --- a/arch/x86/mm/maccess.c +++ b/arch/x86/mm/maccess.c @@ -9,13 +9,10 @@ static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits) return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits); } -bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict) +bool probe_kernel_read_allowed(const void *unsafe_src, size_t size) { unsigned long vaddr = (unsigned long)unsafe_src; - if (!strict) - return true; - /* * Range covering the highest possible canonical userspace address * as well as non-canonical address range. For the canonical range @@ -25,10 +22,8 @@ bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict) canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr; } #else -bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict) +bool probe_kernel_read_allowed(const void *unsafe_src, size_t size) { - if (!strict) - return true; return (unsigned long)unsafe_src >= TASK_SIZE_MAX; } #endif -- cgit v1.2.3-59-g8ed1b