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2019-01-04make 'user_access_begin()' do 'access_ok()'Linus Torvalds1-4/+5
Originally, the rule used to be that you'd have to do access_ok() separately, and then user_access_begin() before actually doing the direct (optimized) user access. But experience has shown that people then decide not to do access_ok() at all, and instead rely on it being implied by other operations or similar. Which makes it very hard to verify that the access has actually been range-checked. If you use the unsafe direct user accesses, hardware features (either SMAP - Supervisor Mode Access Protection - on x86, or PAN - Privileged Access Never - on ARM) do force you to use user_access_begin(). But nothing really forces the range check. By putting the range check into user_access_begin(), we actually force people to do the right thing (tm), and the range check vill be visible near the actual accesses. We have way too long a history of people trying to avoid them. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-05-16kill strlen_user()Al Viro1-34/+0
no callers, no consistent semantics, no sane way to use it... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-08-08unsafe_[get|put]_user: change interface to use a error target labelLinus Torvalds1-4/+3
When I initially added the unsafe_[get|put]_user() helpers in commit 5b24a7a2aa20 ("Add 'unsafe' user access functions for batched accesses"), I made the mistake of modeling the interface on our traditional __[get|put]_user() functions, which return zero on success, or -EFAULT on failure. That interface is fairly easy to use, but it's actually fairly nasty for good code generation, since it essentially forces the caller to check the error value for each access. In particular, since the error handling is already internally implemented with an exception handler, and we already use "asm goto" for various other things, we could fairly easily make the error cases just jump directly to an error label instead, and avoid the need for explicit checking after each operation. So switch the interface to pass in an error label, rather than checking the error value in the caller. Best do it now before we start growing more users (the signal handling code in particular would be a good place to use the new interface). So rather than if (unsafe_get_user(x, ptr)) ... handle error .. the interface is now unsafe_get_user(x, ptr, label); where an error during the user mode fetch will now just cause a jump to 'label' in the caller. Right now the actual _implementation_ of this all still ends up being a "if (err) goto label", and does not take advantage of any exception label tricks, but for "unsafe_put_user()" in particular it should be fairly straightforward to convert to using the exception table model. Note that "unsafe_get_user()" is much harder to convert to a clever exception table model, because current versions of gcc do not allow the use of "asm goto" (for the exception) with output values (for the actual value to be fetched). But that is hopefully not a limitation in the long term. [ Also note that it might be a good idea to switch unsafe_get_user() to actually _return_ the value it fetches from user space, but this commit only changes the error handling semantics ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-17Use the new batched user accesses in generic user string handlingLinus Torvalds1-4/+14
This converts the generic user string functions to use the batched user access functions. It makes a big difference on Skylake, which is the first x86 microarchitecture to implement SMAP. The STAC/CLAC instructions are not very fast, and doing them for each access inside the loop that copies strings from user space (which is what the pathname handling does for every pathname the kernel uses, for example) is very inefficient. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-23Merge branch 'sched-core-for-linus' of ↵Linus Torvalds1-2/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The main changes are: - lockless wakeup support for futexes and IPC message queues (Davidlohr Bueso, Peter Zijlstra) - Replace spinlocks with atomics in thread_group_cputimer(), to improve scalability (Jason Low) - NUMA balancing improvements (Rik van Riel) - SCHED_DEADLINE improvements (Wanpeng Li) - clean up and reorganize preemption helpers (Frederic Weisbecker) - decouple page fault disabling machinery from the preemption counter, to improve debuggability and robustness (David Hildenbrand) - SCHED_DEADLINE documentation updates (Luca Abeni) - topology CPU masks cleanups (Bartosz Golaszewski) - /proc/sched_debug improvements (Srikar Dronamraju)" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (79 commits) sched/deadline: Remove needless parameter in dl_runtime_exceeded() sched: Remove superfluous resetting of the p->dl_throttled flag sched/deadline: Drop duplicate init_sched_dl_class() declaration sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target sched/deadline: Make init_sched_dl_class() __init sched/deadline: Optimize pull_dl_task() sched/preempt: Add static_key() to preempt_notifiers sched/preempt: Fix preempt notifiers documentation about hlist_del() within unsafe iteration sched/stop_machine: Fix deadlock between multiple stop_two_cpus() sched/debug: Add sum_sleep_runtime to /proc/<pid>/sched sched/debug: Replace vruntime with wait_sum in /proc/sched_debug sched/debug: Properly format runnable tasks in /proc/sched_debug sched/numa: Only consider less busy nodes as numa balancing destinations Revert 095bebf61a46 ("sched/numa: Do not move past the balance point if unbalanced") sched/fair: Prevent throttling in early pick_next_task_fair() preempt: Reorganize the notrace definitions a bit preempt: Use preempt_schedule_context() as the official tracing preemption point sched: Make preempt_schedule_context() function-tracing safe x86: Remove cpu_sibling_mask() and cpu_core_mask() x86: Replace cpu_**_mask() with topology_**_cpumask() ...
2015-06-03lib: Clarify the return value of strnlen_user()Jan Kara1-1/+8
strnlen_user() can return a number in a range 0 to count + sizeof(unsigned long) - 1. Clarify the comment at the top of the function so that users don't think the function returns at most count+1. Signed-off-by: Jan Kara <jack@suse.cz> [ Also added commentary about preferably not using this function ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-02lib: Fix strnlen_user() to not touch memory after specified maximumJan Kara1-1/+2
If the specified maximum length of the string is a multiple of unsigned long, we would load one long behind the specified maximum. If that happens to be in a next page, we can hit a page fault although we were not expected to. Fix the off-by-one bug in the test whether we are at the end of the specified range. Signed-off-by: Jan Kara <jack@suse.cz> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-05-19mm/uaccess, mm/fault: Clarify that uaccess may only sleep if pagefaults are ↵David Hildenbrand1-2/+4
enabled In general, non-atomic variants of user access functions must not sleep if pagefaults are disabled. Let's update all relevant comments in uaccess code. This also reflects the might_sleep() checks in might_fault(). Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: benh@kernel.crashing.org Cc: bigeasy@linutronix.de Cc: borntraeger@de.ibm.com Cc: daniel.vetter@intel.com Cc: heiko.carstens@de.ibm.com Cc: herbert@gondor.apana.org.au Cc: hocko@suse.cz Cc: hughd@google.com Cc: mst@redhat.com Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: schwidefsky@de.ibm.com Cc: yang.shi@windriver.com Link: http://lkml.kernel.org/r/1431359540-32227-4-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-05-28lib: Fix generic strnlen_user for 32-bit big-endian machinesPaul Mackerras1-1/+1
The aligned_byte_mask() definition is wrong for 32-bit big-endian machines: the "7-(n)" part of the definition assumes a long is 8 bytes. This fixes it by using BITS_PER_LONG - 8 instead of 8*7. Tested on 32-bit and 64-bit PowerPC. Signed-off-by: Paul Mackerras <paulus@samba.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-26lib: add generic strnlen_user() functionLinus Torvalds1-0/+138
This adds a new generic optimized strnlen_user() function that uses the <asm/word-at-a-time.h> infrastructure to portably do efficient string handling. In many ways, strnlen is much simpler than strncpy, and in particular we can always pre-align the words we load from memory. That means that all the worries about alignment etc are a non-issue, so this one can easily be used on any architecture. You obviously do have to do the appropriate word-at-a-time.h macros. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>