- Aug 20, 2017
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Daniel Borkmann authored
Avoid two successive functions calls for the map in map lookup, first is the bpf_map_lookup_elem() helper call, and second the callback via map->ops->map_lookup_elem() to get to the map in map implementation. Implementation inlines array and htab flavor for map in map lookups. Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Acked-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
David S. Miller <davem@davemloft.net>
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Daniel Borkmann authored
Commit 9015d2f5 ("bpf: inline htab_map_lookup_elem()") was making the assumption that a direct call emission to the function __htab_map_lookup_elem() will always work out for JITs. This is currently true since all JITs we have are for 64 bit archs, but in case of 32 bit JITs like upcoming arm32, we get a NULL pointer dereference when executing the call to __htab_map_lookup_elem() since passed arguments are of a different size (due to pointer args) than what we do out of BPF. Guard and thus limit this for now for the current 64 bit JITs only. Reported-by:
Shubham Bansal <illusionist.neo@gmail.com> Signed-off-by:
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Martin KaFai Lau authored
The current map creation API does not allow to provide the numa-node preference. The memory usually comes from where the map-creation-process is running. The performance is not ideal if the bpf_prog is known to always run in a numa node different from the map-creation-process. One of the use case is sharding on CPU to different LRU maps (i.e. an array of LRU maps). Here is the test result of map_perf_test on the INNER_LRU_HASH_PREALLOC test if we force the lru map used by CPU0 to be allocated from a remote numa node: [ The machine has 20 cores. CPU0-9 at node 0. CPU10-19 at node 1 ] ># taskset -c 10 ./map_perf_test 512 8 1260000 8000000 5:inner_lru_hash_map_perf pre-alloc 1628380 events per sec 4:inner_lru_hash_map_perf pre-alloc 1626396 events per sec 3:inner_lru_hash_map_perf pre-alloc 1626144 events per sec 6:inner_lru_hash_map_perf pre-alloc 1621657 events per sec 2:inner_lru_hash_map_perf pre-alloc 1621534 events per sec 1:inner_lru_hash_map_perf pre-alloc 1620292 events per sec 7:inner_lru_hash_map_perf pre-alloc 1613305 events per sec 0:inner_lru_hash_map_perf pre-alloc 1239150 events per sec #<<< After specifying numa node: ># taskset -c 10 ./map_perf_test 512 8 1260000 8000000 5:inner_lru_hash_map_perf pre-alloc 1629627 events per sec 3:inner_lru_hash_map_perf pre-alloc 1628057 events per sec 1:inner_lru_hash_map_perf pre-alloc 1623054 events per sec 6:inner_lru_hash_map_perf pre-alloc 1616033 events per sec 2:inner_lru_hash_map_perf pre-alloc 1614630 events per sec 4:inner_lru_hash_map_perf pre-alloc 1612651 events per sec 7:inner_lru_hash_map_perf pre-alloc 1609337 events per sec 0:inner_lru_hash_map_perf pre-alloc 1619340 events per sec #<<< This patch adds one field, numa_node, to the bpf_attr. Since numa node 0 is a valid node, a new flag BPF_F_NUMA_NODE is also added. The numa_node field is honored if and only if the BPF_F_NUMA_NODE flag is set. Numa node selection is not supported for percpu map. This patch does not change all the kmalloc. F.e. 'htab = kzalloc()' is not changed since the object is small enough to stay in the cache. Signed-off-by:
Martin KaFai Lau <kafai@fb.com> Acked-by:
Alexei Starovoitov <ast@fb.com> Signed-off-by:
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- Aug 18, 2017
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Martin KaFai Lau authored
In check_map_func_compatibility(), a 'break' has been accidentally removed for the BPF_MAP_TYPE_ARRAY_OF_MAPS and BPF_MAP_TYPE_HASH_OF_MAPS cases. This patch adds it back. Fixes: 174a79ff ("bpf: sockmap with sk redirect support") Cc: John Fastabend <john.fastabend@gmail.com> Signed-off-by:
John Fastabend <john.fastabend@gmail.com> Acked-by:
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Dan Carpenter authored
"map" is a valid pointer. We wanted to return "err" instead. Also let's return a zero literal at the end. Fixes: 174a79ff ("bpf: sockmap with sk redirect support") Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Acked-by:
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- Aug 17, 2017
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Daniel Borkmann authored
In smap_do_verdict(), the fall-through branch leads to call preempt_enable() twice for the SK_REDIRECT, which creates an imbalance. Only enable it for all remaining cases again. Fixes: 174a79ff ("bpf: sockmap with sk redirect support") Reported-by:
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Daniel Borkmann authored
Using parent->regs[] when propagating REG_LIVE_READ for spilled regs doesn't work since parent->regs[] denote the set of normal registers but not spilled ones. Propagate to the correct regs. Fixes: dc503a8a ("bpf/verifier: track liveness for pruning") Reported-by:
Edward Cree <ecree@solarflare.com> Signed-off-by:
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- Aug 16, 2017
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John Fastabend authored
Resolve issues with !CONFIG_BPF_SYSCALL and !STREAM_PARSER net/core/filter.c: In function ‘do_sk_redirect_map’: net/core/filter.c:1881:3: error: implicit declaration of function ‘__sock_map_lookup_elem’ [-Werror=implicit-function-declaration] sk = __sock_map_lookup_elem(ri->map, ri->ifindex); ^ net/core/filter.c:1881:6: warning: assignment makes pointer from integer without a cast [enabled by default] sk = __sock_map_lookup_elem(ri->map, ri->ifindex); Fixes: 174a79ff ("bpf: sockmap with sk redirect support") Reported-by:
Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:
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John Fastabend authored
psock will uninitialized in default case we need to do the same psock lookup and check as in other branch. Fixes compile warning below. kernel/bpf/sockmap.c: In function ‘smap_state_change’: kernel/bpf/sockmap.c:156:21: warning: ‘psock’ may be used uninitialized in this function [-Wmaybe-uninitialized] struct smap_psock *psock; Fixes: 174a79ff ("bpf: sockmap with sk redirect support") Reported-by:
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John Fastabend authored
In the devmap alloc map logic we check to ensure that the sizeof the values are not greater than KMALLOC_MAX_SIZE. But, in the dev map case we ensure the value size is 4bytes earlier in the function because all values should be netdev ifindex values. The second check is harmless but is not needed so remove it. Signed-off-by:
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John Fastabend authored
Signed-off-by:
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John Fastabend authored
Recently we added a new map type called dev map used to forward XDP packets between ports (6093ec2d). This patches introduces a similar notion for sockets. A sockmap allows users to add participating sockets to a map. When sockets are added to the map enough context is stored with the map entry to use the entry with a new helper bpf_sk_redirect_map(map, key, flags) This helper (analogous to bpf_redirect_map in XDP) is given the map and an entry in the map. When called from a sockmap program, discussed below, the skb will be sent on the socket using skb_send_sock(). With the above we need a bpf program to call the helper from that will then implement the send logic. The initial site implemented in this series is the recv_sock hook. For this to work we implemented a map attach command to add attributes to a map. In sockmap we add two programs a parse program and a verdict program. The parse program uses strparser to build messages and pass them to the verdict program. The parse programs use the normal strparser semantics. The verdict program is of type SK_SKB. The verdict program returns a verdict SK_DROP, or SK_REDIRECT for now. Additional actions may be added later. When SK_REDIRECT is returned, expected when bpf program uses bpf_sk_redirect_map(), the sockmap logic will consult per cpu variables set by the helper routine and pull the sock entry out of the sock map. This pattern follows the existing redirect logic in cls and xdp programs. This gives the flow, recv_sock -> str_parser (parse_prog) -> verdict_prog -> skb_send_sock \ -> kfree_skb As an example use case a message based load balancer may use specific logic in the verdict program to select the sock to send on. Sample programs are provided in future patches that hopefully illustrate the user interfaces. Also selftests are in follow-on patches. Signed-off-by:
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John Fastabend authored
bpf_prog_inc_not_zero will be used by upcoming sockmap patches this patch simply exports it so we can pull it in. Signed-off-by:
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Daniel Borkmann authored
James reported that on MIPS32 bpf_trace_printk() is currently broken while MIPS64 works fine: bpf_trace_printk() uses conditional operators to attempt to pass different types to __trace_printk() depending on the format operators. This doesn't work as intended on 32-bit architectures where u32 and long are passed differently to u64, since the result of C conditional operators follows the "usual arithmetic conversions" rules, such that the values passed to __trace_printk() will always be u64 [causing issues later in the va_list handling for vscnprintf()]. For example the samples/bpf/tracex5 test printed lines like below on MIPS32, where the fd and buf have come from the u64 fd argument, and the size from the buf argument: [...] 1180.941542: 0x00000001: write(fd=1, buf= (null), size=6258688) Instead of this: [...] 1625.616026: 0x00000001: write(fd=1, buf=009e4000, size=512) One way to get it working is to expand various combinations of argument types into 8 different combinations for 32 bit and 64 bit kernels. Fix tested by James on MIPS32 and MIPS64 as well that it resolves the issue. Fixes: 9c959c86 ("tracing: Allow BPF programs to call bpf_trace_printk()") Reported-by:James Hogan <james.hogan@imgtec.com> Tested-by:
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- Aug 15, 2017
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Edward Cree authored
State of a register doesn't matter if it wasn't read in reaching an exit; a write screens off all reads downstream of it from all explored_states upstream of it. This allows us to prune many more branches; here are some processed insn counts for some Cilium programs: Program before after bpf_lb_opt_-DLB_L3.o 6515 3361 bpf_lb_opt_-DLB_L4.o 8976 5176 bpf_lb_opt_-DUNKNOWN.o 2960 1137 bpf_lxc_opt_-DDROP_ALL.o 95412 48537 bpf_lxc_opt_-DUNKNOWN.o 141706 78718 bpf_netdev.o 24251 17995 bpf_overlay.o 10999 9385 The runtime is also improved; here are 'time' results in ms: Program before after bpf_lb_opt_-DLB_L3.o 24 6 bpf_lb_opt_-DLB_L4.o 26 11 bpf_lb_opt_-DUNKNOWN.o 11 2 bpf_lxc_opt_-DDROP_ALL.o 1288 139 bpf_lxc_opt_-DUNKNOWN.o 1768 234 bpf_netdev.o 62 31 bpf_overlay.o 15 13 Signed-off-by:
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- Aug 10, 2017
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Nadav Amit authored
Patch series "fixes of TLB batching races", v6. It turns out that Linux TLB batching mechanism suffers from various races. Races that are caused due to batching during reclamation were recently handled by Mel and this patch-set deals with others. The more fundamental issue is that concurrent updates of the page-tables allow for TLB flushes to be batched on one core, while another core changes the page-tables. This other core may assume a PTE change does not require a flush based on the updated PTE value, while it is unaware that TLB flushes are still pending. This behavior affects KSM (which may result in memory corruption) and MADV_FREE and MADV_DONTNEED (which may result in incorrect behavior). A proof-of-concept can easily produce the wrong behavior of MADV_DONTNEED. Memory corruption in KSM is harder to produce in practice, but was observed by hacking the kernel and adding a delay before flushing and replacing the KSM page. Finally, there is also one memory barrier missing, which may affect architectures with weak memory model. This patch (of 7): Setting and clearing mm->tlb_flush_pending can be performed by multiple threads, since mmap_sem may only be acquired for read in task_numa_work(). If this happens, tlb_flush_pending might be cleared while one of the threads still changes PTEs and batches TLB flushes. This can lead to the same race between migration and change_protection_range() that led to the introduction of tlb_flush_pending. The result of this race was data corruption, which means that this patch also addresses a theoretically possible data corruption. An actual data corruption was not observed, yet the race was was confirmed by adding assertion to check tlb_flush_pending is not set by two threads, adding artificial latency in change_protection_range() and using sysctl to reduce kernel.numa_balancing_scan_delay_ms. Link: http://lkml.kernel.org/r/20170802000818.4760-2-namit@vmware.com Fixes: 20841405 ("mm: fix TLB flush race between migration, and change_protection_range") Signed-off-by:
Nadav Amit <namit@vmware.com> Acked-by:
Mel Gorman <mgorman@suse.de> Acked-by:
Rik van Riel <riel@redhat.com> Acked-by:
Minchan Kim <minchan@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Russell King <linux@armlinux.org.uk> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Johannes Weiner authored
As Tetsuo points out: "Commit 385386cf ("mm: vmstat: move slab statistics from zone to node counters") broke "Slab:" field of /proc/meminfo . It shows nearly 0kB" In addition to /proc/meminfo, this problem also affects the slab counters OOM/allocation failure info dumps, can cause early -ENOMEM from overcommit protection, and miscalculate image size requirements during suspend-to-disk. This is because the patch in question switched the slab counters from the zone level to the node level, but forgot to update the global accessor functions to read the aggregate node data instead of the aggregate zone data. Use global_node_page_state() to access the global slab counters. Fixes: 385386cf ("mm: vmstat: move slab statistics from zone to node counters") Link: http://lkml.kernel.org/r/20170801134256.5400-1-hannes@cmpxchg.org Signed-off-by:
Johannes Weiner <hannes@cmpxchg.org> Reported-by:
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Acked-by:
Michal Hocko <mhocko@suse.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Stefan Agner <stefan@agner.ch> Signed-off-by:
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- Aug 09, 2017
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Daniel Borkmann authored
Enable the newly added jump opcodes, main parts are in two different areas, namely direct packet access and dynamic map value access. For the direct packet access, we now allow for the following two new patterns to match in order to trigger markings with find_good_pkt_pointers(): Variant 1 (access ok when taking the branch): 0: (61) r2 = *(u32 *)(r1 +76) 1: (61) r3 = *(u32 *)(r1 +80) 2: (bf) r0 = r2 3: (07) r0 += 8 4: (ad) if r0 < r3 goto pc+2 R0=pkt(id=0,off=8,r=0) R1=ctx R2=pkt(id=0,off=0,r=0) R3=pkt_end R10=fp 5: (b7) r0 = 0 6: (95) exit from 4 to 7: R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8) R3=pkt_end R10=fp 7: (71) r0 = *(u8 *)(r2 +0) 8: (05) goto pc-4 5: (b7) r0 = 0 6: (95) exit processed 11 insns, stack depth 0 Variant 2 (access ok on fall-through): 0: (61) r2 = *(u32 *)(r1 +76) 1: (61) r3 = *(u32 *)(r1 +80) 2: (bf) r0 = r2 3: (07) r0 += 8 4: (bd) if r3 <= r0 goto pc+1 R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8) R3=pkt_end R10=fp 5: (71) r0 = *(u8 *)(r2 +0) 6: (b7) r0 = 1 7: (95) exit from 4 to 6: R0=pkt(id=0,off=8,r=0) R1=ctx R2=pkt(id=0,off=0,r=0) R3=pkt_end R10=fp 6: (b7) r0 = 1 7: (95) exit processed 10 insns, stack depth 0 The above two basically just swap the branches where we need to handle an exception and allow packet access compared to the two already existing variants for find_good_pkt_pointers(). For the dynamic map value access, we add the new instructions to reg_set_min_max() and reg_set_min_max_inv() in order to learn bounds. Verifier test cases for both are added in a follow-up patch. Signed-off-by: -
Daniel Borkmann authored
Currently, eBPF only understands BPF_JGT (>), BPF_JGE (>=), BPF_JSGT (s>), BPF_JSGE (s>=) instructions, this means that particularly *JLT/*JLE counterparts involving immediates need to be rewritten from e.g. X < [IMM] by swapping arguments into [IMM] > X, meaning the immediate first is required to be loaded into a register Y := [IMM], such that then we can compare with Y > X. Note that the destination operand is always required to be a register. This has the downside of having unnecessarily increased register pressure, meaning complex program would need to spill other registers temporarily to stack in order to obtain an unused register for the [IMM]. Loading to registers will thus also affect state pruning since we need to account for that register use and potentially those registers that had to be spilled/filled again. As a consequence slightly more stack space might have been used due to spilling, and BPF programs are a bit longer due to extra code involving the register load and potentially required spill/fills. Thus, add BPF_JLT (<), BPF_JLE (<=), BPF_JSLT (s<), BPF_JSLE (s<=) counterparts to the eBPF instruction set. Modifying LLVM to remove the NegateCC() workaround in a PoC patch at [1] and allowing it to also emit the new instructions resulted in cilium's BPF programs that are injected into the fast-path to have a reduced program length in the range of 2-3% (e.g. accumulated main and tail call sections from one of the object file reduced from 4864 to 4729 insns), reduced complexity in the range of 10-30% (e.g. accumulated sections reduced in one of the cases from 116432 to 88428 insns), and reduced stack usage in the range of 1-5% (e.g. accumulated sections from one of the object files reduced from 824 to 784b). The modification for LLVM will be incorporated in a backwards compatible way. Plan is for LLVM to have i) a target specific option to offer a possibility to explicitly enable the extension by the user (as we have with -m target specific extensions today for various CPU insns), and ii) have the kernel checked for presence of the extensions and enable them transparently when the user is selecting more aggressive options such as -march=native in a bpf target context. (Other frontends generating BPF byte code, e.g. ply can probe the kernel directly for its code generation.) [1] https://github.com/borkmann/llvm/tree/bpf-insns Signed-off-by:
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Mel Gorman authored
Commit 65d8fc77 ("futex: Remove requirement for lock_page() in get_futex_key()") removed an unnecessary lock_page() with the side-effect that page->mapping needed to be treated very carefully. Two defensive warnings were added in case any assumption was missed and the first warning assumed a correct application would not alter a mapping backing a futex key. Since merging, it has not triggered for any unexpected case but Mark Rutland reported the following bug triggering due to the first warning. kernel BUG at kernel/futex.c:679! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 3695 Comm: syz-executor1 Not tainted 4.13.0-rc3-00020-g307fec773ba3 #3 Hardware name: linux,dummy-virt (DT) task: ffff80001e271780 task.stack: ffff000010908000 PC is at get_futex_key+0x6a4/0xcf0 kernel/futex.c:679 LR is at get_futex_key+0x6a4/0xcf0 kernel/futex.c:679 pc : [<ffff00000821ac14>] lr : [<ffff00000821ac14>] pstate: 80000145 The fact that it's a bug instead of a warning was due to an unrelated arm64 problem, but the warning itself triggered because the underlying mapping changed. This is an application issue but from a kernel perspective it's a recoverable situation and the warning is unnecessary so this patch removes the warning. The warning may potentially be triggered with the following test program from Mark although it may be necessary to adjust NR_FUTEX_THREADS to be a value smaller than the number of CPUs in the system. #include <linux/futex.h> #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #include <sys/syscall.h> #include <sys/time.h> #include <unistd.h> #define NR_FUTEX_THREADS 16 pthread_t threads[NR_FUTEX_THREADS]; void *mem; #define MEM_PROT (PROT_READ | PROT_WRITE) #define MEM_SIZE 65536 static int futex_wrapper(int *uaddr, int op, int val, const struct timespec *timeout, int *uaddr2, int val3) { syscall(SYS_futex, uaddr, op, val, timeout, uaddr2, val3); } void *poll_futex(void *unused) { for (;;) { futex_wrapper(mem, FUTEX_CMP_REQUEUE_PI, 1, NULL, mem + 4, 1); } } int main(int argc, char *argv[]) { int i; mem = mmap(NULL, MEM_SIZE, MEM_PROT, MAP_SHARED | MAP_ANONYMOUS, -1, 0); printf("Mapping @ %p\n", mem); printf("Creating futex threads...\n"); for (i = 0; i < NR_FUTEX_THREADS; i++) pthread_create(&threads[i], NULL, poll_futex, NULL); printf("Flipping mapping...\n"); for (;;) { mmap(mem, MEM_SIZE, MEM_PROT, MAP_FIXED | MAP_SHARED | MAP_ANONYMOUS, -1, 0); } return 0; } Reported-and-tested-by:
Mark Rutland <mark.rutland@arm.com> Signed-off-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Cc: stable@vger.kernel.org # 4.7+ Signed-off-by:
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Mickaël Salaün authored
The function check_uarg_tail_zero() was created from bpf(2) for BPF_OBJ_GET_INFO_BY_FD without taking the access_ok() nor the PAGE_SIZE checks. Make this checks more generally available while unlikely to be triggered, extend the memory range check and add an explanation including why the ToCToU should not be a security concern. Signed-off-by:
Mickaël Salaün <mic@digikod.net> Acked-by:
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Mickaël Salaün authored
The function check_uarg_tail_zero() may be useful for other part of the code in the syscall.c file. Move this function at the beginning of the file. Signed-off-by:
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Edward Cree authored
The more detailed value tracking can reduce the effectiveness of pruning for some programs. So, to avoid rejecting previously valid programs, up the limit to 128kinsns. Hopefully we will be able to bring this back down later by improving pruning performance. Signed-off-by:
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Edward Cree authored
Signed-off-by:
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Edward Cree authored
Allows us to, sometimes, combine information from a signed check of one bound and an unsigned check of the other. We now track the full range of possible values, rather than restricting ourselves to [0, 1<<30) and considering anything beyond that as unknown. While this is probably not necessary, it makes the code more straightforward and symmetrical between signed and unsigned bounds. Signed-off-by:
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Edward Cree authored
Unifies adjusted and unadjusted register value types (e.g. FRAME_POINTER is now just a PTR_TO_STACK with zero offset). Tracks value alignment by means of tracking known & unknown bits. This also replaces the 'reg->imm' (leading zero bits) calculations for (what were) UNKNOWN_VALUEs. If pointer leaks are allowed, and adjust_ptr_min_max_vals returns -EACCES, treat the pointer as an unknown scalar and try again, because we might be able to conclude something about the result (e.g. pointer & 0x40 is either 0 or 0x40). Verifier hooks in the netronome/nfp driver were changed to match the new data structures. Signed-off-by:
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- Aug 07, 2017
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John Fastabend authored
Originally we used a mutex to protect concurrent devmap update and delete operations from racing with netdev unregister notifier callbacks. The notifier hook is needed because we increment the netdev ref count when a dev is added to the devmap. This ensures the netdev reference is valid in the datapath. However, we don't want to block unregister events, hence the initial mutex and notifier handler. The concern was in the notifier hook we search the map for dev entries that hold a refcnt on the net device being torn down. But, in order to do this we require two steps, (i) dereference the netdev: dev = rcu_dereference(map[i]) (ii) test ifindex: dev->ifindex == removing_ifindex and then finally we can swap in the NULL dev in the map via an xchg operation, xchg(map[i], NULL) The danger here is a concurrent update could run a different xchg op concurrently leading us to replace the new dev with a NULL dev incorrectly. CPU 1 CPU 2 notifier hook bpf devmap update dev = rcu_dereference(map[i]) dev = rcu_dereference(map[i]) xchg(map[i]), new_dev); rcu_call(dev,...) xchg(map[i], NULL) The above flow would create the incorrect state with the dev reference in the update path being lost. To resolve this the original code used a mutex around the above block. However, updates, deletes, and lookups occur inside rcu critical sections so we can't use a mutex in this context safely. Fortunately, by writing slightly better code we can avoid the mutex altogether. If CPU 1 in the above example uses a cmpxchg and _only_ replaces the dev reference in the map when it is in fact the expected dev the race is removed completely. The two cases being illustrated here, first the race condition, CPU 1 CPU 2 notifier hook bpf devmap update dev = rcu_dereference(map[i]) dev = rcu_dereference(map[i]) xchg(map[i]), new_dev); rcu_call(dev,...) odev = cmpxchg(map[i], dev, NULL) Now we can test the cmpxchg return value, detect odev != dev and abort. Or in the good case, CPU 1 CPU 2 notifier hook bpf devmap update dev = rcu_dereference(map[i]) odev = cmpxchg(map[i], dev, NULL) [...] Now 'odev == dev' and we can do proper cleanup. And viola the original race we tried to solve with a mutex is corrected and the trace noted by Sasha below is resolved due to removal of the mutex. Note: When walking the devmap and removing dev references as needed we depend on the core to fail any calls to dev_get_by_index() using the ifindex of the device being removed. This way we do not race with the user while searching the devmap. Additionally, the mutex was also protecting list add/del/read on the list of maps in-use. This patch converts this to an RCU list and spinlock implementation. This protects the list from concurrent alloc/free operations. The notifier hook walks this list so it uses RCU read semantics. BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747 in_atomic(): 1, irqs_disabled(): 0, pid: 16315, name: syz-executor1 1 lock held by syz-executor1/16315: #0: (rcu_read_lock){......}, at: [<ffffffff8c363bc2>] map_delete_elem kernel/bpf/syscall.c:577 [inline] #0: (rcu_read_lock){......}, at: [<ffffffff8c363bc2>] SYSC_bpf kernel/bpf/syscall.c:1427 [inline] #0: (rcu_read_lock){......}, at: [<ffffffff8c363bc2>] SyS_bpf+0x1d32/0x4ba0 kernel/bpf/syscall.c:1388 Fixes: 2ddf71e2 ("net: add notifier hooks for devmap bpf map") Reported-by:Sasha Levin <alexander.levin@verizon.com> Signed-off-by:
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Yonghong Song authored
Currently, bpf programs cannot be attached to sys_enter_* and sys_exit_* style tracepoints. The iovisor/bcc issue #748 (https://github.com/iovisor/bcc/issues/748 ) documents this issue. For example, if you try to attach a bpf program to tracepoints syscalls/sys_enter_newfstat, you will get the following error: # ./tools/trace.py t:syscalls:sys_enter_newfstat Ioctl(PERF_EVENT_IOC_SET_BPF): Invalid argument Failed to attach BPF to tracepoint The main reason is that syscalls/sys_enter_* and syscalls/sys_exit_* tracepoints are treated differently from other tracepoints and there is no bpf hook to it. This patch adds bpf support for these syscalls tracepoints by . permitting bpf attachment in ioctl PERF_EVENT_IOC_SET_BPF . calling bpf programs in perf_syscall_enter and perf_syscall_exit The legality of bpf program ctx access is also checked. Function trace_event_get_offsets returns correct max offset for each specific syscall tracepoint, which is compared against the maximum offset access in bpf program. Signed-off-by:
Yonghong Song <yhs@fb.com> Acked-by:
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- Aug 06, 2017
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Dmitry V. Levin authored
The latest change of compat_sys_sigpending in commit 8f13621a ("sigpending(): move compat to native") has broken it in two ways. First, it tries to write 4 bytes more than userspace expects: sizeof(old_sigset_t) == sizeof(long) == 8 instead of sizeof(compat_old_sigset_t) == sizeof(u32) == 4. Second, on big endian architectures these bytes are being written in the wrong order. This bug was found by strace test suite. Reported-by:
Anatoly Pugachev <matorola@gmail.com> Inspired-by:
Eugene Syromyatnikov <evgsyr@gmail.com> Fixes: 8f13621a ("sigpending(): move compat to native") Signed-off-by:
Dmitry V. Levin <ldv@altlinux.org> Acked-by:
Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:
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- Aug 03, 2017
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Dima Zavin authored
In codepaths that use the begin/retry interface for reading mems_allowed_seq with irqs disabled, there exists a race condition that stalls the patch process after only modifying a subset of the static_branch call sites. This problem manifested itself as a deadlock in the slub allocator, inside get_any_partial. The loop reads mems_allowed_seq value (via read_mems_allowed_begin), performs the defrag operation, and then verifies the consistency of mem_allowed via the read_mems_allowed_retry and the cookie returned by xxx_begin. The issue here is that both begin and retry first check if cpusets are enabled via cpusets_enabled() static branch. This branch can be rewritted dynamically (via cpuset_inc) if a new cpuset is created. The x86 jump label code fully synchronizes across all CPUs for every entry it rewrites. If it rewrites only one of the callsites (specifically the one in read_mems_allowed_retry) and then waits for the smp_call_function(do_sync_core) to complete while a CPU is inside the begin/retry section with IRQs off and the mems_allowed value is changed, we can hang. This is because begin() will always return 0 (since it wasn't patched yet) while retry() will test the 0 against the actual value of the seq counter. The fix is to use two different static keys: one for begin (pre_enable_key) and one for retry (enable_key). In cpuset_inc(), we first bump the pre_enable key to ensure that cpuset_mems_allowed_begin() always return a valid seqcount if are enabling cpusets. Similarly, when disabling cpusets via cpuset_dec(), we first ensure that callers of cpuset_mems_allowed_retry() will start ignoring the seqcount value before we let cpuset_mems_allowed_begin() return 0. The relevant stack traces of the two stuck threads: CPU: 1 PID: 1415 Comm: mkdir Tainted: G L 4.9.36-00104-g540c51286237 #4 Hardware name: Default string Default string/Hardware, BIOS 4.29.1-20170526215256 05/26/2017 task: ffff8817f9c28000 task.stack: ffffc9000ffa4000 RIP: smp_call_function_many+0x1f9/0x260 Call Trace: smp_call_function+0x3b/0x70 on_each_cpu+0x2f/0x90 text_poke_bp+0x87/0xd0 arch_jump_label_transform+0x93/0x100 __jump_label_update+0x77/0x90 jump_label_update+0xaa/0xc0 static_key_slow_inc+0x9e/0xb0 cpuset_css_online+0x70/0x2e0 online_css+0x2c/0xa0 cgroup_apply_control_enable+0x27f/0x3d0 cgroup_mkdir+0x2b7/0x420 kernfs_iop_mkdir+0x5a/0x80 vfs_mkdir+0xf6/0x1a0 SyS_mkdir+0xb7/0xe0 entry_SYSCALL_64_fastpath+0x18/0xad ... CPU: 2 PID: 1 Comm: init Tainted: G L 4.9.36-00104-g540c51286237 #4 Hardware name: Default string Default string/Hardware, BIOS 4.29.1-20170526215256 05/26/2017 task: ffff8818087c0000 task.stack: ffffc90000030000 RIP: int3+0x39/0x70 Call Trace: <#DB> ? ___slab_alloc+0x28b/0x5a0 <EOE> ? copy_process.part.40+0xf7/0x1de0 __slab_alloc.isra.80+0x54/0x90 copy_process.part.40+0xf7/0x1de0 copy_process.part.40+0xf7/0x1de0 kmem_cache_alloc_node+0x8a/0x280 copy_process.part.40+0xf7/0x1de0 _do_fork+0xe7/0x6c0 _raw_spin_unlock_irq+0x2d/0x60 trace_hardirqs_on_caller+0x136/0x1d0 entry_SYSCALL_64_fastpath+0x5/0xad do_syscall_64+0x27/0x350 SyS_clone+0x19/0x20 do_syscall_64+0x60/0x350 entry_SYSCALL64_slow_path+0x25/0x25 Link: http://lkml.kernel.org/r/20170731040113.14197-1-dmitriyz@waymo.com Fixes: 46e700ab ("mm, page_alloc: remove unnecessary taking of a seqlock when cpusets are disabled") Signed-off-by:Dima Zavin <dmitriyz@waymo.com> Reported-by:
Cliff Spradlin <cspradlin@waymo.com> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Christopher Lameter <cl@linux.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: <stable@vger.kernel.org> Signed-off-by:
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- Aug 02, 2017
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Kefeng Wang authored
After commit 3d375d78 ("mm: update callers to use HASH_ZERO flag"), drop unused pidhash_size in pidhash_init(). Link: http://lkml.kernel.org/r/1500389267-49222-1-git-send-email-wangkefeng.wang@huawei.com Signed-off-by:
Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by:
Pavel Tatashin <Pasha.Tatashin@Oracle.com> Signed-off-by:
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- Aug 01, 2017
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Matija Glavinic Pecotic authored
For e.g. HZ=100, timer being 430 jiffies in the future, and 32 bit unsigned int, there is an overflow on unsigned int right-hand side of the expression which results with wrong values being returned. Type cast the multiplier to 64bit to avoid that issue. Fixes: 46c8f0b0 ("timers: Fix get_next_timer_interrupt() computation") Signed-off-by:
Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Reviewed-by:
Alexander Sverdlin <alexander.sverdlin@nokia.com> Cc: khilman@baylibre.com Cc: akpm@linux-foundation.org Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/a7900f04-2a21-c9fd-67be-ab334d459ee5@nokia.com
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- Jul 30, 2017
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Daniel Borkmann authored
bpf_prog_size(prog->len) is not the correct length we want to dump back to user space. The code in bpf_prog_get_info_by_fd() uses this to copy prog->insnsi to user space, but bpf_prog_size(prog->len) also includes the size of struct bpf_prog itself plus program instructions and is usually used either in context of accounting or for bpf_prog_alloc() et al, thus we copy out of bounds in bpf_prog_get_info_by_fd() potentially. Use the correct bpf_prog_insn_size() instead. Fixes: 1e270976 ("bpf: Add BPF_OBJ_GET_INFO_BY_FD") Signed-off-by:
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- Jul 29, 2017
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Daniel Borkmann authored
err in bpf_prog_get_info_by_fd() still holds 0 at that time from prior check_uarg_tail_zero() check. Explicitly return -EFAULT instead, so user space can be notified of buggy behavior. Fixes: 1e270976 ("bpf: Add BPF_OBJ_GET_INFO_BY_FD") Signed-off-by:
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- Jul 28, 2017
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Michael Bringmann authored
There is an underlying assumption/trade-off in many layers of the Linux system that CPU <-> node mapping is static. This is despite the presence of features like NUMA and 'hotplug' that support the dynamic addition/ removal of fundamental system resources like CPUs and memory. PowerPC systems, however, do provide extensive features for the dynamic change of resources available to a system. Currently, there is little or no synchronization protection around the updating of the CPU <-> node mapping, and the export/update of this information for other layers / modules. In systems which can change this mapping during 'hotplug', like PowerPC, the information is changing underneath all layers that might reference it. This patch attempts to ensure that a valid, usable cpumask attribute is used by the workqueue infrastructure when setting up new resource pools. It prevents a crash that has been observed when an 'empty' cpumask is passed along to the worker/task scheduling code. It is intended as a temporary workaround until a more fundamental review and correction of the issue can be done. [With additions to the patch provided by Tejun Hao <tj@kernel.org>] Signed-off-by:
Michael Bringmann <mwb@linux.vnet.ibm.com> Signed-off-by:
Tejun Heo <tj@kernel.org>
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- Jul 27, 2017
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Thomas Gleixner authored
That commit was part of the changes moving x86 to the generic CPU hotplug interrupt migration code. The force flag was required on x86 before the hierarchical irqdomain rework, but invoking set_affinity() with force=true stayed and had no side effects. At some point in the past, the force flag got repurposed to support the exynos timer interrupt affinity setting to a not yet online CPU, so the interrupt controller callback does not verify the supplied affinity mask against cpu_online_mask. Setting the flag in the CPU hotplug code causes the cpu online masking to be blocked on these irq controllers and results in potentially affining an interrupt to the CPU which is unplugged, i.e. instead of moving it away, it's just reassigned to it. As the force flags is not longer needed on x86, it's safe to revert that patch so the ARM irqchips which use the force flag work again. Add comments to that effect, so this won't happen again. Note: The online mask handling should be done in the generic code and the force flag and the masking in the irq chips removed all together, but that's not a change possible for 4.13. Fixes: 77f85e66 ("genirq/cpuhotplug: Set force affinity flag on hotplug migration") Reported-by:
Will Deacon <will.deacon@arm.com> Signed-off-by:
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- Jul 25, 2017
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Tejun Heo authored
5c0338c6 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") automatically enabled ordered attribute for unbound workqueues w/ max_active == 1. Because ordered workqueues reject max_active and some attribute changes, this implicit ordered mode broke cases where the user creates an unbound workqueue w/ max_active == 1 and later explicitly changes the related attributes. This patch distinguishes explicit and implicit ordered setting and overrides from attribute changes if implict. Signed-off-by:
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Jonathan Corbet authored
The kerneldoc comments for try_to_wake_up_local() were out of date, leading to these documentation build warnings: ./kernel/sched/core.c:2080: warning: No description found for parameter 'rf' ./kernel/sched/core.c:2080: warning: Excess function parameter 'cookie' description in 'try_to_wake_up_local' Update the comment to reflect current reality and give us some peace and quiet. Signed-off-by:
Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-doc@vger.kernel.org Link: http://lkml.kernel.org/r/20170724135628.695cecfc@lwn.net Signed-off-by:
Ingo Molnar <mingo@kernel.org>
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- Jul 24, 2017
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Dan Carpenter authored
We forgot to set the error code on two error paths which means that we return ERR_PTR(0) which is NULL. The caller, find_and_alloc_map(), is not expecting that and will have a NULL dereference. Fixes: 546ac1ff ("bpf: add devmap, a map for storing net device references") Signed-off-by:
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Edward Cree authored
We have to subtract the src max from the dst min, and vice-versa, since (e.g.) the smallest result comes from the largest subtrahend. Fixes: 48461135 ("bpf: allow access into map value arrays") Signed-off-by:
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