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2019-11-02uaccess: Add strict non-pagefault kernel-space read functionDaniel Borkmann1-1/+24
Add two new probe_kernel_read_strict() and strncpy_from_unsafe_strict() helpers which by default alias to the __probe_kernel_read() and the __strncpy_from_unsafe(), respectively, but can be overridden by archs which have non-overlapping address ranges for kernel space and user space in order to bail out with -EFAULT when attempting to probe user memory including non-canonical user access addresses [0]: 4-level page tables: user-space mem: 0x0000000000000000 - 0x00007fffffffffff non-canonical: 0x0000800000000000 - 0xffff7fffffffffff 5-level page tables: user-space mem: 0x0000000000000000 - 0x00ffffffffffffff non-canonical: 0x0100000000000000 - 0xfeffffffffffffff The idea is that these helpers are complementary to the probe_user_read() and strncpy_from_unsafe_user() which probe user-only memory. Both added helpers here do the same, but for kernel-only addresses. Both set of helpers are going to be used for BPF tracing. They also explicitly avoid throwing the splat for non-canonical user addresses from 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). For compat, the current probe_kernel_read() and strncpy_from_unsafe() are left as-is. [0] Documentation/x86/x86_64/mm.txt Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: x86@kernel.org Link: https://lore.kernel.org/bpf/eefeefd769aa5a013531f491a71f0936779e916b.1572649915.git.daniel@iogearbox.net
2019-11-02uaccess: Add non-pagefault user-space write functionDaniel Borkmann1-4/+41
Commit 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions") missed to add probe write function, therefore factor out a probe_write_common() helper with most logic of probe_kernel_write() except setting KERNEL_DS, and add a new probe_user_write() helper so it can be used from BPF side. Again, on some archs, the user address space and kernel address space can co-exist and be overlapping, so in such case, setting KERNEL_DS would mean that the given address is treated as being in kernel address space. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Link: https://lore.kernel.org/bpf/9df2542e68141bfa3addde631441ee45503856a8.1572649915.git.daniel@iogearbox.net
2019-07-18Merge tag 'trace-v5.3' of ↵Linus Torvalds1-6/+116
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "The main changes in this release include: - Add user space specific memory reading for kprobes - Allow kprobes to be executed earlier in boot The rest are mostly just various clean ups and small fixes" * tag 'trace-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits) tracing: Make trace_get_fields() global tracing: Let filter_assign_type() detect FILTER_PTR_STRING tracing: Pass type into tracing_generic_entry_update() ftrace/selftest: Test if set_event/ftrace_pid exists before writing ftrace/selftests: Return the skip code when tracing directory not configured in kernel tracing/kprobe: Check registered state using kprobe tracing/probe: Add trace_event_call accesses APIs tracing/probe: Add probe event name and group name accesses APIs tracing/probe: Add trace flag access APIs for trace_probe tracing/probe: Add trace_event_file access APIs for trace_probe tracing/probe: Add trace_event_call register API for trace_probe tracing/probe: Add trace_probe init and free functions tracing/uprobe: Set print format when parsing command tracing/kprobe: Set print format right after parsed command kprobes: Fix to init kprobes in subsys_initcall tracepoint: Use struct_size() in kmalloc() ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS ftrace: Enable trampoline when rec count returns back to one tracing/kprobe: Do not run kprobe boot tests if kprobe_event is on cmdline tracing: Make a separate config for trace event self tests ...
2019-05-26uaccess: Add non-pagefault user-space read functionsMasami Hiramatsu1-6/+116
Add probe_user_read(), strncpy_from_unsafe_user() and strnlen_unsafe_user() which allows caller to access user-space in IRQ context. Current probe_kernel_read() and strncpy_from_unsafe() are not available for user-space memory, because it sets KERNEL_DS while accessing data. On some arch, user address space and kernel address space can be co-exist, but others can not. In that case, setting KERNEL_DS means given address is treated as a kernel address space. Also strnlen_user() is only available from user context since it can sleep if pagefault is enabled. To access user-space memory without pagefault, we need these new functions which sets USER_DS while accessing the data. Link: http://lkml.kernel.org/r/155789869802.26965.4940338412595759063.stgit@devnote2 Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-05-21treewide: Add SPDX license identifier for missed filesThomas Gleixner1-0/+1
Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-25Revert "x86/fault: BUG() when uaccess helpers fault on kernel addresses"Linus Torvalds1-6/+0
This reverts commit 9da3f2b74054406f87dff7101a569217ffceb29b. It was well-intentioned, but wrong. Overriding the exception tables for instructions for random reasons is just wrong, and that is what the new code did. It caused problems for tracing, and it caused problems for strncpy_from_user(), because the new checks made perfectly valid use cases break, rather than catch things that did bad things. Unchecked user space accesses are a problem, but that's not a reason to add invalid checks that then people have to work around with silly flags (in this case, that 'kernel_uaccess_faults_ok' flag, which is just an odd way to say "this commit was wrong" and was sprinked into random places to hide the wrongness). The real fix to unchecked user space accesses is to get rid of the special "let's not check __get_user() and __put_user() at all" logic. Make __{get|put}_user() be just aliases to the regular {get|put}_user() functions, and make it impossible to access user space without having the proper checks in places. The raison d'être of the special double-underscore versions used to be that the range check was expensive, and if you did multiple user accesses, you'd do the range check up front (like the signal frame handling code, for example). But SMAP (on x86) and PAN (on ARM) have made that optimization pointless, because the _real_ expense is the "set CPU flag to allow user space access". Do let's not break the valid cases to catch invalid cases that shouldn't even exist. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Kees Cook <keescook@chromium.org> Cc: Tobin C. Harding <tobin@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Jann Horn <jannh@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-09-03x86/fault: BUG() when uaccess helpers fault on kernel addressesJann Horn1-0/+6
There have been multiple kernel vulnerabilities that permitted userspace to pass completely unchecked pointers through to userspace accessors: - the waitid() bug - commit 96ca579a1ecc ("waitid(): Add missing access_ok() checks") - the sg/bsg read/write APIs - the infiniband read/write APIs These don't happen all that often, but when they do happen, it is hard to test for them properly; and it is probably also hard to discover them with fuzzing. Even when an unmapped kernel address is supplied to such buggy code, it just returns -EFAULT instead of doing a proper BUG() or at least WARN(). Try to make such misbehaving code a bit more visible by refusing to do a fixup in the pagefault handler code when a userspace accessor causes a #PF on a kernel address and the current context isn't whitelisted. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: kernel-hardening@lists.openwall.com Cc: dvyukov@google.com Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: Borislav Petkov <bp@alien8.de> Link: https://lkml.kernel.org/r/20180828201421.157735-7-jannh@google.com
2018-02-07mm: docs: fix parameter names mismatchMike Rapoport1-1/+1
There are several places where parameter descriptions do no match the actual code. Fix it. Link: http://lkml.kernel.org/r/1516700871-22279-3-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-23x86: remove more uaccess_32.h complexityLinus Torvalds1-2/+1
I'm looking at trying to possibly merge the 32-bit and 64-bit versions of the x86 uaccess.h implementation, but first this needs to be cleaned up. For example, the 32-bit version of "__copy_from_user_inatomic()" is mostly the special cases for the constant size, and it's actually almost never relevant. Most users aren't actually using a constant size anyway, and the few cases that do small constant copies are better off just using __get_user() instead. So get rid of the unnecessary complexity. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06mm/maccess.c: actually return -EFAULT from strncpy_from_unsafeRasmus Villemoes1-1/+1
As far as I can tell, strncpy_from_unsafe never returns -EFAULT. ret is the result of a __copy_from_user_inatomic(), which is 0 for success and positive (in this case necessarily 1) for access error - it is never negative. So we were always returning the length of the, possibly truncated, destination string. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06uaccess: reimplement probe_kernel_address() using probe_kernel_read()Andrew Morton1-0/+5
probe_kernel_address() is basically the same as the (later added) probe_kernel_read(). The return value on EFAULT is a bit different: probe_kernel_address() returns number-of-bytes-not-copied whereas probe_kernel_read() returns -EFAULT. All callers have been checked, none cared. probe_kernel_read() can be overridden by the architecture whereas probe_kernel_address() cannot. parisc, blackfin and um do this, to insert additional checking. Hence this patch possibly fixes obscure bugs, although there are only two probe_kernel_address() callsites outside arch/. My first attempt involved removing probe_kernel_address() entirely and converting all callsites to use probe_kernel_read() directly, but that got tiresome. This patch shrinks mm/slab_common.o by 218 bytes. For a single probe_kernel_address() callsite. Cc: Steven Miao <realmz6@gmail.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-08-31lib: move strncpy_from_unsafe() into mm/maccess.cAlexei Starovoitov1-0/+41
To fix build errors: kernel/built-in.o: In function `bpf_trace_printk': bpf_trace.c:(.text+0x11a254): undefined reference to `strncpy_from_unsafe' kernel/built-in.o: In function `fetch_memory_string': trace_kprobe.c:(.text+0x11acf8): undefined reference to `strncpy_from_unsafe' move strncpy_from_unsafe() next to probe_kernel_read/write() which use the same memory access style. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Reported-by: Guenter Roeck <linux@roeck-us.net> Fixes: 1a6877b9c0c2 ("lib: introduce strncpy_from_unsafe()") Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-10-31mm: Map most files to use export.h instead of module.hPaul Gortmaker1-1/+1
The files changed within are only using the EXPORT_SYMBOL macro variants. They are not using core modular infrastructure and hence don't need module.h but only the export.h header. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2011-05-26maccess,probe_kernel: Make write/read src const void *Steven Rostedt1-4/+4
The functions probe_kernel_write() and probe_kernel_read() do not modify the src pointer. Allow const pointers to be passed in without the need of a typecast. Acked-by: Mike Frysinger <vapier@gentoo.org> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1305824936.1465.4.camel@gandalf.stny.rr.com
2010-10-27MN10300: Save frame pointer in thread_info struct rather than global varDavid Howells1-1/+1
Save the current exception frame pointer in the thread_info struct rather than in a global variable as the latter makes SMP tricky, especially when preemption is also enabled. This also replaces __frame with current_frame() and rearranges header file inclusions to make it all compile. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Akira Takeuchi <takeuchi.akr@jp.panasonic.com>
2010-01-07maccess,probe_kernel: Allow arch specific override probe_kernel_(read|write)Jason Wessel1-2/+9
Some archs such as blackfin, would like to have an arch specific probe_kernel_read() and probe_kernel_write() implementation which can fall back to the generic implementation if no special operations are needed. CC: Thomas Gleixner <tglx@linutronix.de> CC: Ingo Molnar <mingo@elte.hu> Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-06-12[S390] maccess: add weak attribute to probe_kernel_writeHeiko Carstens1-1/+1
probe_kernel_write() gets used to write to the kernel address space. E.g. to patch the kernel (kgdb, ftrace, kprobes...). Some architectures however enable write protection for the kernel text section, so that writes to this region would fault. This patch allows to specify an architecture specific version of probe_kernel_write() which allows to handle and bypass write protection of the text segment. That way it is still possible to catch random writes to kernel text and explicitly allow writes via this interface. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-04-17kgdb: fix optional arch functions and probe_kernel_*Jason Wessel1-0/+6
Fix two regressions dealing with the kgdb core. 1) kgdb_skipexception and kgdb_post_primary_code are optional functions that are only required on archs that need special exception fixups. 2) The kernel address space scope must be set on any probe_kernel_* function or archs such as ARCH=arm will not allow access to the kernel memory space. As an example, it is required to allow the full kernel address space is when you the kernel debugger to inspect a system call. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-17uaccess: add probe_kernel_write()Ingo Molnar1-0/+49
add probe_kernel_read() and probe_kernel_write(). Uninlined and restricted to kernel range memory only, as suggested by Linus. Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>