[16/23] maccess: always use strict semantics for probe_kernel_read

Message ID	20200521152301.2587579-17-hch@lst.de
State	New
Headers	show Return-Path: <SRS0=hUHR=7D=vger.kernel.org=netdev-owner@kernel.org> From: Christoph Hellwig <hch@lst.de> To: x86@kernel.org, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Masami Hiramatsu <mhiramat@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org> Cc: linux-parisc@vger.kernel.org, linux-um@lists.infradead.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 16/23] maccess: always use strict semantics for probe_kernel_read Date: Thu, 21 May 2020 17:22:54 +0200 Message-Id: <20200521152301.2587579-17-hch@lst.de> In-Reply-To: <20200521152301.2587579-1-hch@lst.de> References: <20200521152301.2587579-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk
Series	[01/23] maccess: unexport probe_kernel_write and probe_user_write \| expand [01/23] maccess: unexport probe_kernel_write and probe_user_write [03/23] maccess: remove duplicate kerneldoc comments [06/23] maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault [07/23] maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault [09/23] maccess: remove probe_read_common and probe_write_common [10/23] maccess: unify the probe kernel arch hooks [12/23] bpf: handle the compat string in bpf_trace_copy_string better [14/23] tracing/kprobes: handle mixed kernel/userspace probes better [16/23] maccess: always use strict semantics for probe_kernel_read [18/23] maccess: allow architectures to provide kernel probing directly [21/23] maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault [22/23] maccess: rename probe_kernel_address to get_kernel_nofault

diff --git a/arch/parisc/lib/memcpy.c b/arch/parisc/lib/memcpy.c index 5b75c35d1da0d..94a9fe2702c2f 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 ad2c538ce497c..e929c0966696c 100644 --- a/arch/um/kernel/maccess.c +++ b/arch/um/kernel/maccess.c @@ -7,7 +7,7 @@ #include <linux/kernel.h> #include <os.h> -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 a96a56ff16109..a5ed03ac9b10f 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)vaddr >= TASK_SIZE_MAX; } #endif diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index d7d98ff345b3d..58e9f3dc1cf13 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -301,11 +301,9 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src, return 0; } -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); extern long probe_kernel_read(void *dst, const void *src, size_t size); -extern long probe_kernel_read_strict(void *dst, const void *src, size_t size); extern long probe_user_read(void *dst, const void __user *src, size_t size); extern long notrace probe_kernel_write(void *dst, const void *src, size_t size); diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 43566cd2a8180..d9781c894c38b 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -196,7 +196,7 @@ bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) if (unlikely(ret < 0)) goto fail; - ret = probe_kernel_read_strict(dst, unsafe_ptr, size); + ret = probe_kernel_read(dst, unsafe_ptr, size); if (unlikely(ret < 0)) goto fail; return ret; diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 4aeaef53ba970..b1f21d558e454 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1222,7 +1222,7 @@ fetch_store_strlen(unsigned long addr) #endif do { - ret = probe_kernel_read_strict(&c, (u8 *)addr + len, 1); + ret = probe_kernel_read(&c, (u8 *)addr + len, 1); len++; } while (c && ret == 0 && len < MAX_STRING_SIZE); @@ -1300,7 +1300,7 @@ probe_mem_read(void *dest, void *src, size_t size) if ((unsigned long)src < TASK_SIZE) return probe_mem_read_user(dest, src, size); #endif - return probe_kernel_read_strict(dest, src, size); + return probe_kernel_read(dest, src, size); } /* Note that we don't verify it, since the code does not come from user space */ diff --git a/mm/maccess.c b/mm/maccess.c index df82fde34307f..81a85c1e71165 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -6,36 +6,13 @@ #include <linux/mm.h> #include <linux/uaccess.h> -static long __probe_kernel_read(void *dst, const void *src, size_t size, - bool strict); - -bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size, - bool strict) +bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size) { return true; } /** - * probe_kernel_read(): safely attempt to read from any location - * @dst: pointer to the buffer that shall take the data - * @src: address to read from - * @size: size of the data chunk - * - * Same as probe_kernel_read_strict() except that for architectures with - * not fully separated user and kernel address spaces this function also works - * for user address tanges. - * - * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely - * separate kernel and user address spaces, and also a bad idea otherwise. - */ -long probe_kernel_read(void *dst, const void *src, size_t size) -{ - return __probe_kernel_read(dst, src, size, false); -} -EXPORT_SYMBOL_GPL(probe_kernel_read); - -/** - * probe_kernel_read_strict(): safely attempt to read from kernel-space + * probe_kernel_read(): safely attempt to read from kernel-space * @dst: pointer to the buffer that shall take the data * @src: address to read from * @size: size of the data chunk @@ -48,18 +25,12 @@ EXPORT_SYMBOL_GPL(probe_kernel_read); * probe_kernel_read() suitable for use within regions where the caller * already holds mmap_sem, or other locks which nest inside mmap_sem. */ -long probe_kernel_read_strict(void *dst, const void *src, size_t size) -{ - return __probe_kernel_read(dst, src, size, true); -} - -static long __probe_kernel_read(void *dst, const void *src, size_t size, - bool strict) +long probe_kernel_read(void *dst, const void *src, size_t size) { long ret; mm_segment_t old_fs = get_fs(); - if (!probe_kernel_read_allowed(src, size, strict)) + if (!probe_kernel_read_allowed(src, size)) return -EFAULT; set_fs(KERNEL_DS); @@ -73,6 +44,7 @@ static long __probe_kernel_read(void *dst, const void *src, size_t size, return -EFAULT; return 0; } +EXPORT_SYMBOL_GPL(probe_kernel_read); /** * probe_user_read(): safely attempt to read from a user-space location @@ -180,7 +152,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count) if (unlikely(count <= 0)) return 0; - if (!probe_kernel_read_allowed(unsafe_addr, count, true)) + if (!probe_kernel_read_allowed(unsafe_addr, count)) return -EFAULT; set_fs(KERNEL_DS);

[16/23] maccess: always use strict semantics for probe_kernel_read

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