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2020-03-04bpf: Add test ops for BPF_PROG_TYPE_TRACINGKP Singh
The current fexit and fentry tests rely on a different program to exercise the functions they attach to. Instead of doing this, implement the test operations for tracing which will also be used for BPF_MODIFY_RETURN in a subsequent patch. Also, clean up the fexit test to use the generated skeleton. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200304191853.1529-7-kpsingh@chromium.org
2020-03-04bpf: Attachment verification for BPF_MODIFY_RETURNKP Singh
- Allow BPF_MODIFY_RETURN attachment only to functions that are: * Whitelisted for error injection by checking within_error_injection_list. Similar discussions happened for the bpf_override_return helper. * security hooks, this is expected to be cleaned up with the LSM changes after the KRSI patches introduce the LSM_HOOK macro: https://lore.kernel.org/bpf/20200220175250.10795-1-kpsingh@chromium.org/ - The attachment is currently limited to functions that return an int. This can be extended later other types (e.g. PTR). Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200304191853.1529-5-kpsingh@chromium.org
2020-03-04bpf: Introduce BPF_MODIFY_RETURNKP Singh
When multiple programs are attached, each program receives the return value from the previous program on the stack and the last program provides the return value to the attached function. The fmod_ret bpf programs are run after the fentry programs and before the fexit programs. The original function is only called if all the fmod_ret programs return 0 to avoid any unintended side-effects. The success value, i.e. 0 is not currently configurable but can be made so where user-space can specify it at load time. For example: int func_to_be_attached(int a, int b) { <--- do_fentry do_fmod_ret: <update ret by calling fmod_ret> if (ret != 0) goto do_fexit; original_function: <side_effects_happen_here> } <--- do_fexit The fmod_ret program attached to this function can be defined as: SEC("fmod_ret/func_to_be_attached") int BPF_PROG(func_name, int a, int b, int ret) { // This will skip the original function logic. return 1; } The first fmod_ret program is passed 0 in its return argument. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200304191853.1529-4-kpsingh@chromium.org
2020-03-04bpf: Refactor trampoline update codeKP Singh
As we need to introduce a third type of attachment for trampolines, the flattened signature of arch_prepare_bpf_trampoline gets even more complicated. Refactor the prog and count argument to arch_prepare_bpf_trampoline to use bpf_tramp_progs to simplify the addition and accounting for new attachment types. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200304191853.1529-2-kpsingh@chromium.org
2020-03-02bpf: Introduce pinnable bpf_link abstractionAndrii Nakryiko
Introduce bpf_link abstraction, representing an attachment of BPF program to a BPF hook point (e.g., tracepoint, perf event, etc). bpf_link encapsulates ownership of attached BPF program, reference counting of a link itself, when reference from multiple anonymous inodes, as well as ensures that release callback will be called from a process context, so that users can safely take mutex locks and sleep. Additionally, with a new abstraction it's now possible to generalize pinning of a link object in BPF FS, allowing to explicitly prevent BPF program detachment on process exit by pinning it in a BPF FS and let it open from independent other process to keep working with it. Convert two existing bpf_link-like objects (raw tracepoint and tracing BPF program attachments) into utilizing bpf_link framework, making them pinnable in BPF FS. More FD-based bpf_links will be added in follow up patches. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200303043159.323675-2-andriin@fb.com
2020-02-29Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-nextDavid S. Miller
Alexei Starovoitov says: ==================== pull-request: bpf-next 2020-02-28 The following pull-request contains BPF updates for your *net-next* tree. We've added 41 non-merge commits during the last 7 day(s) which contain a total of 49 files changed, 1383 insertions(+), 499 deletions(-). The main changes are: 1) BPF and Real-Time nicely co-exist. 2) bpftool feature improvements. 3) retrieve bpf_sk_storage via INET_DIAG. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-27bpf: INET_DIAG support in bpf_sk_storageMartin KaFai Lau
This patch adds INET_DIAG support to bpf_sk_storage. 1. Although this series adds bpf_sk_storage diag capability to inet sk, bpf_sk_storage is in general applicable to all fullsock. Hence, the bpf_sk_storage logic will operate on SK_DIAG_* nlattr. The caller will pass in its specific nesting nlattr (e.g. INET_DIAG_*) as the argument. 2. The request will be like: INET_DIAG_REQ_SK_BPF_STORAGES (nla_nest) (defined in latter patch) SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32) SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32) ...... Considering there could have multiple bpf_sk_storages in a sk, instead of reusing INET_DIAG_INFO ("ss -i"), the user can select some specific bpf_sk_storage to dump by specifying an array of SK_DIAG_BPF_STORAGE_REQ_MAP_FD. If no SK_DIAG_BPF_STORAGE_REQ_MAP_FD is specified (i.e. an empty INET_DIAG_REQ_SK_BPF_STORAGES), it will dump all bpf_sk_storages of a sk. 3. The reply will be like: INET_DIAG_BPF_SK_STORAGES (nla_nest) (defined in latter patch) SK_DIAG_BPF_STORAGE (nla_nest) SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32) SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit) SK_DIAG_BPF_STORAGE (nla_nest) SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32) SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit) ...... 4. Unlike other INET_DIAG info of a sk which is pretty static, the size required to dump the bpf_sk_storage(s) of a sk is dynamic as the system adding more bpf_sk_storage_map. It is hard to set a static min_dump_alloc size. Hence, this series learns it at the runtime and adjust the cb->min_dump_alloc as it iterates all sk(s) of a system. The "unsigned int *res_diag_size" in bpf_sk_storage_diag_put() is for this purpose. The next patch will update the cb->min_dump_alloc as it iterates the sk(s). Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200225230421.1975729-1-kafai@fb.com
2020-02-27Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netDavid S. Miller
The mptcp conflict was overlapping additions. The SMC conflict was an additional and removal happening at the same time. Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-28bpf: Replace zero-length array with flexible-array memberGustavo A. R. Silva
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200227001744.GA3317@embeddedor
2020-02-27Merge tag 'audit-pr-20200226' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit Pull audit fixes from Paul Moore: "Two fixes for problems found by syzbot: - Moving audit filter structure fields into a union caused some problems in the code which populates that filter structure. We keep the union (that idea is a good one), but we are fixing the code so that it doesn't needlessly set fields in the union and mess up the error handling. - The audit_receive_msg() function wasn't validating user input as well as it should in all cases, we add the necessary checks" * tag 'audit-pr-20200226' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit: audit: always check the netlink payload length in audit_receive_msg() audit: fix error handling in audit_data_to_entry()
2020-02-26Merge tag 'trace-v5.6-rc2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing and bootconfig updates: "Fixes and changes to bootconfig before it goes live in a release. Change in API of bootconfig (before it comes live in a release): - Have a magic value "BOOTCONFIG" in initrd to know a bootconfig exists - Set CONFIG_BOOT_CONFIG to 'n' by default - Show error if "bootconfig" on cmdline but not compiled in - Prevent redefining the same value - Have a way to append values - Added a SELECT BLK_DEV_INITRD to fix a build failure Synthetic event fixes: - Switch to raw_smp_processor_id() for recording CPU value in preempt section. (No care for what the value actually is) - Fix samples always recording u64 values - Fix endianess - Check number of values matches number of fields - Fix a printing bug Fix of trace_printk() breaking postponed start up tests Make a function static that is only used in a single file" * tag 'trace-v5.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: bootconfig: Fix CONFIG_BOOTTIME_TRACING dependency issue bootconfig: Add append value operator support bootconfig: Prohibit re-defining value on same key bootconfig: Print array as multiple commands for legacy command line bootconfig: Reject subkey and value on same parent key tools/bootconfig: Remove unneeded error message silencer bootconfig: Add bootconfig magic word for indicating bootconfig explicitly bootconfig: Set CONFIG_BOOT_CONFIG=n by default tracing: Clear trace_state when starting trace bootconfig: Mark boot_config_checksum() static tracing: Disable trace_printk() on post poned tests tracing: Have synthetic event test use raw_smp_processor_id() tracing: Fix number printing bug in print_synth_event() tracing: Check that number of vals matches number of synth event fields tracing: Make synth_event trace functions endian-correct tracing: Make sure synth_event_trace() example always uses u64
2020-02-26signal: avoid double atomic counter increments for user accountingLinus Torvalds
When queueing a signal, we increment both the users count of pending signals (for RLIMIT_SIGPENDING tracking) and we increment the refcount of the user struct itself (because we keep a reference to the user in the signal structure in order to correctly account for it when freeing). That turns out to be fairly expensive, because both of them are atomic updates, and particularly under extreme signal handling pressure on big machines, you can get a lot of cache contention on the user struct. That can then cause horrid cacheline ping-pong when you do these multiple accesses. So change the reference counting to only pin the user for the _first_ pending signal, and to unpin it when the last pending signal is dequeued. That means that when a user sees a lot of concurrent signal queuing - which is the only situation when this matters - the only atomic access needed is generally the 'sigpending' count update. This was noticed because of a particularly odd timing artifact on a dual-socket 96C/192T Cascade Lake platform: when you get into bad contention, on that machine for some reason seems to be much worse when the contention happens in the upper 32-byte half of the cacheline. As a result, the kernel test robot will-it-scale 'signal1' benchmark had an odd performance regression simply due to random alignment of the 'struct user_struct' (and pointed to a completely unrelated and apparently nonsensical commit for the regression). Avoiding the double increments (and decrements on the dequeueing side, of course) makes for much less contention and hugely improved performance on that will-it-scale microbenchmark. Quoting Feng Tang: "It makes a big difference, that the performance score is tripled! bump from original 17000 to 54000. Also the gap between 5.0-rc6 and 5.0-rc6+Jiri's patch is reduced to around 2%" [ The "2% gap" is the odd cacheline placement difference on that platform: under the extreme contention case, the effect of which half of the cacheline was hot was 5%, so with the reduced contention the odd timing artifact is reduced too ] It does help in the non-contended case too, but is not nearly as noticeable. Reported-and-tested-by: Feng Tang <feng.tang@intel.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Huang, Ying <ying.huang@intel.com> Cc: Philip Li <philip.li@intel.com> Cc: Andi Kleen <andi.kleen@intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-02-25bootconfig: Fix CONFIG_BOOTTIME_TRACING dependency issueMasami Hiramatsu
Since commit d8a953ddde5e ("bootconfig: Set CONFIG_BOOT_CONFIG=n by default") also changed the CONFIG_BOOTTIME_TRACING to select CONFIG_BOOT_CONFIG to show the boot-time tracing on the menu, it introduced wrong dependencies with BLK_DEV_INITRD as below. WARNING: unmet direct dependencies detected for BOOT_CONFIG Depends on [n]: BLK_DEV_INITRD [=n] Selected by [y]: - BOOTTIME_TRACING [=y] && TRACING_SUPPORT [=y] && FTRACE [=y] && TRACING [=y] This makes the CONFIG_BOOT_CONFIG selects CONFIG_BLK_DEV_INITRD to fix this error and make CONFIG_BOOTTIME_TRACING=n by default, so that both boot-time tracing and boot configuration off but those appear on the menu list. Link: http://lkml.kernel.org/r/158264140162.23842.11237423518607465535.stgit@devnote2 Fixes: d8a953ddde5e ("bootconfig: Set CONFIG_BOOT_CONFIG=n by default") Reported-by: Randy Dunlap <rdunlap@infradead.org> Compiled-tested-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-24bpf/stackmap: Dont trylock mmap_sem with PREEMPT_RT and interrupts disabledDavid Miller
In a RT kernel down_read_trylock() cannot be used from NMI context and up_read_non_owner() is another problematic issue. So in such a configuration, simply elide the annotated stackmap and just report the raw IPs. In the longer term, it might be possible to provide a atomic friendly versions of the page cache traversal which will at least provide the info if the pages are resident and don't need to be paged in. [ tglx: Use IS_ENABLED() to avoid the #ifdeffery, fixup the irq work callback and add a comment ] Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145644.708960317@linutronix.de
2020-02-24bpf, lpm: Make locking RT friendlyThomas Gleixner
The LPM trie map cannot be used in contexts like perf, kprobes and tracing as this map type dynamically allocates memory. The memory allocation happens with a raw spinlock held which is a truly spinning lock on a PREEMPT RT enabled kernel which disables preemption and interrupts. As RT does not allow memory allocation from such a section for various reasons, convert the raw spinlock to a regular spinlock. On a RT enabled kernel these locks are substituted by 'sleeping' spinlocks which provide the proper protection but keep the code preemptible. On a non-RT kernel regular spinlocks map to raw spinlocks, i.e. this does not cause any functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145644.602129531@linutronix.de
2020-02-24bpf: Prepare hashtab locking for PREEMPT_RTThomas Gleixner
PREEMPT_RT forbids certain operations like memory allocations (even with GFP_ATOMIC) from atomic contexts. This is required because even with GFP_ATOMIC the memory allocator calls into code pathes which acquire locks with long held lock sections. To ensure the deterministic behaviour these locks are regular spinlocks, which are converted to 'sleepable' spinlocks on RT. The only true atomic contexts on an RT kernel are the low level hardware handling, scheduling, low level interrupt handling, NMIs etc. None of these contexts should ever do memory allocations. As regular device interrupt handlers and soft interrupts are forced into thread context, the existing code which does spin_lock*(); alloc(GPF_ATOMIC); spin_unlock*(); just works. In theory the BPF locks could be converted to regular spinlocks as well, but the bucket locks and percpu_freelist locks can be taken from arbitrary contexts (perf, kprobes, tracepoints) which are required to be atomic contexts even on RT. These mechanisms require preallocated maps, so there is no need to invoke memory allocations within the lock held sections. BPF maps which need dynamic allocation are only used from (forced) thread context on RT and can therefore use regular spinlocks which in turn allows to invoke memory allocations from the lock held section. To achieve this make the hash bucket lock a union of a raw and a regular spinlock and initialize and lock/unlock either the raw spinlock for preallocated maps or the regular variant for maps which require memory allocations. On a non RT kernel this distinction is neither possible nor required. spinlock maps to raw_spinlock and the extra code and conditional is optimized out by the compiler. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145644.509685912@linutronix.de
2020-02-24bpf: Factor out hashtab bucket lock operationsThomas Gleixner
As a preparation for making the BPF locking RT friendly, factor out the hash bucket lock operations into inline functions. This allows to do the necessary RT modification in one place instead of sprinkling it all over the place. No functional change. The now unused htab argument of the lock/unlock functions will be used in the next step which adds PREEMPT_RT support. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145644.420416916@linutronix.de
2020-02-24bpf: Replace open coded recursion prevention in sys_bpf()Thomas Gleixner
The required protection is that the caller cannot be migrated to a different CPU as these functions end up in places which take either a hash bucket lock or might trigger a kprobe inside the memory allocator. Both scenarios can lead to deadlocks. The deadlock prevention is per CPU by incrementing a per CPU variable which temporarily blocks the invocation of BPF programs from perf and kprobes. Replace the open coded preempt_[dis|en]able and __this_cpu_[inc|dec] pairs with the new helper functions. These functions are already prepared to make BPF work on PREEMPT_RT enabled kernels. No functional change for !RT kernels. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145644.317843926@linutronix.de
2020-02-24bpf: Use recursion prevention helpers in hashtab codeThomas Gleixner
The required protection is that the caller cannot be migrated to a different CPU as these places take either a hash bucket lock or might trigger a kprobe inside the memory allocator. Both scenarios can lead to deadlocks. The deadlock prevention is per CPU by incrementing a per CPU variable which temporarily blocks the invocation of BPF programs from perf and kprobes. Replace the open coded preempt_disable/enable() and this_cpu_inc/dec() pairs with the new recursion prevention helpers to prepare BPF to work on PREEMPT_RT enabled kernels. On a non-RT kernel the migrate disable/enable in the helpers map to preempt_disable/enable(), i.e. no functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145644.211208533@linutronix.de
2020-02-24bpf: Use migrate_disable/enabe() in trampoline code.David Miller
Instead of preemption disable/enable to reflect the purpose. This allows PREEMPT_RT to substitute it with an actual migration disable implementation. On non RT kernels this is still mapped to preempt_disable/enable(). Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145643.891428873@linutronix.de
2020-02-24bpf: Use bpf_prog_run_pin_on_cpu() at simple call sites.David Miller
All of these cases are strictly of the form: preempt_disable(); BPF_PROG_RUN(...); preempt_enable(); Replace this with bpf_prog_run_pin_on_cpu() which wraps BPF_PROG_RUN() with: migrate_disable(); BPF_PROG_RUN(...); migrate_enable(); On non RT enabled kernels this maps to preempt_disable/enable() and on RT enabled kernels this solely prevents migration, which is sufficient as there is no requirement to prevent reentrancy to any BPF program from a preempting task. The only requirement is that the program stays on the same CPU. Therefore, this is a trivially correct transformation. The seccomp loop does not need protection over the loop. It only needs protection per BPF filter program [ tglx: Converted to bpf_prog_run_pin_on_cpu() ] Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145643.691493094@linutronix.de
2020-02-24bpf: Dont iterate over possible CPUs with interrupts disabledThomas Gleixner
pcpu_freelist_populate() is disabling interrupts and then iterates over the possible CPUs. The reason why this disables interrupts is to silence lockdep because the invoked ___pcpu_freelist_push() takes spin locks. Neither the interrupt disabling nor the locking are required in this function because it's called during initialization and the resulting map is not yet visible to anything. Split out the actual push assignement into an inline, call it from the loop and remove the interrupt disable. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145643.365930116@linutronix.de
2020-02-24bpf: Remove recursion prevention from rcu free callbackThomas Gleixner
If an element is freed via RCU then recursion into BPF instrumentation functions is not a concern. The element is already detached from the map and the RCU callback does not hold any locks on which a kprobe, perf event or tracepoint attached BPF program could deadlock. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145643.259118710@linutronix.de
2020-02-24perf/bpf: Remove preempt disable around BPF invocationThomas Gleixner
The BPF invocation from the perf event overflow handler does not require to disable preemption because this is called from NMI or at least hard interrupt context which is already non-preemptible. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145643.151953573@linutronix.de
2020-02-24bpf/trace: Remove redundant preempt_disable from trace_call_bpf()Thomas Gleixner
Similar to __bpf_trace_run this is redundant because __bpf_trace_run() is invoked from a trace point via __DO_TRACE() which already disables preemption _before_ invoking any of the functions which are attached to a trace point. Remove it and add a cant_sleep() check. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145643.059995527@linutronix.de
2020-02-24bpf: disable preemption for bpf progs attached to uprobeAlexei Starovoitov
trace_call_bpf() no longer disables preemption on its own. All callers of this function has to do it explicitly. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2020-02-24bpf/trace: Remove EXPORT from trace_call_bpf()Thomas Gleixner
All callers are built in. No point to export this. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-02-24bpf/tracing: Remove redundant preempt_disable() in __bpf_trace_run()Thomas Gleixner
__bpf_trace_run() disables preemption around the BPF_PROG_RUN() invocation. This is redundant because __bpf_trace_run() is invoked from a trace point via __DO_TRACE() which already disables preemption _before_ invoking any of the functions which are attached to a trace point. Remove it and add a cant_sleep() check. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145642.847220186@linutronix.de
2020-02-24bpf: Update locking comment in hashtab codeThomas Gleixner
The comment where the bucket lock is acquired says: /* bpf_map_update_elem() can be called in_irq() */ which is not really helpful and aside of that it does not explain the subtle details of the hash bucket locks expecially in the context of BPF and perf, kprobes and tracing. Add a comment at the top of the file which explains the protection scopes and the details how potential deadlocks are prevented. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145642.755793061@linutronix.de
2020-02-24bpf: Enforce preallocation for instrumentation programs on RTThomas Gleixner
Aside of the general unsafety of run-time map allocation for instrumentation type programs RT enabled kernels have another constraint: The instrumentation programs are invoked with preemption disabled, but the memory allocator spinlocks cannot be acquired in atomic context because they are converted to 'sleeping' spinlocks on RT. Therefore enforce map preallocation for these programs types when RT is enabled. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145642.648784007@linutronix.de
2020-02-24bpf: Tighten the requirements for preallocated hash mapsThomas Gleixner
The assumption that only programs attached to perf NMI events can deadlock on memory allocators is wrong. Assume the following simplified callchain: kmalloc() from regular non BPF context cache empty freelist empty lock(zone->lock); tracepoint or kprobe BPF() update_elem() lock(bucket) kmalloc() cache empty freelist empty lock(zone->lock); <- DEADLOCK There are other ways which do not involve locking to create wreckage: kmalloc() from regular non BPF context local_irq_save(); ... obj = slab_first(); kprobe() BPF() update_elem() lock(bucket) kmalloc() local_irq_save(); ... obj = slab_first(); <- Same object as above ... So preallocation _must_ be enforced for all variants of intrusive instrumentation. Unfortunately immediate enforcement would break backwards compatibility, so for now such programs still are allowed to run, but a one time warning is emitted in dmesg and the verifier emits a warning in the verifier log as well so developers are made aware about this and can fix their programs before the enforcement becomes mandatory. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145642.540542802@linutronix.de
2020-02-24audit: always check the netlink payload length in audit_receive_msg()Paul Moore
This patch ensures that we always check the netlink payload length in audit_receive_msg() before we take any action on the payload itself. Cc: stable@vger.kernel.org Reported-by: syzbot+399c44bf1f43b8747403@syzkaller.appspotmail.com Reported-by: syzbot+e4b12d8d202701f08b6d@syzkaller.appspotmail.com Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-02-22audit: fix error handling in audit_data_to_entry()Paul Moore
Commit 219ca39427bf ("audit: use union for audit_field values since they are mutually exclusive") combined a number of separate fields in the audit_field struct into a single union. Generally this worked just fine because they are generally mutually exclusive. Unfortunately in audit_data_to_entry() the overlap can be a problem when a specific error case is triggered that causes the error path code to attempt to cleanup an audit_field struct and the cleanup involves attempting to free a stored LSM string (the lsm_str field). Currently the code always has a non-NULL value in the audit_field.lsm_str field as the top of the for-loop transfers a value into audit_field.val (both .lsm_str and .val are part of the same union); if audit_data_to_entry() fails and the audit_field struct is specified to contain a LSM string, but the audit_field.lsm_str has not yet been properly set, the error handling code will attempt to free the bogus audit_field.lsm_str value that was set with audit_field.val at the top of the for-loop. This patch corrects this by ensuring that the audit_field.val is only set when needed (it is cleared when the audit_field struct is allocated with kcalloc()). It also corrects a few other issues to ensure that in case of error the proper error code is returned. Cc: stable@vger.kernel.org Fixes: 219ca39427bf ("audit: use union for audit_field values since they are mutually exclusive") Reported-by: syzbot+1f4d90ead370d72e450b@syzkaller.appspotmail.com Signed-off-by: Paul Moore <paul@paul-moore.com>
2020-02-22Merge tag 'irq-urgent-2020-02-22' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull irq fixes from Thomas Gleixner: "Two fixes for the irq core code which are follow ups to the recent MSI fixes: - The WARN_ON which was put into the MSI setaffinity callback for paranoia reasons actually triggered via a callchain which escaped when all the possible ways to reach that code were analyzed. The proc/irq/$N/*affinity interfaces have a quirk which came in when ALPHA moved to the generic interface: In case that the written affinity mask does not contain any online CPU it calls into ALPHAs magic auto affinity setting code. A few years later this mechanism was also made available to x86 for no good reasons and in a way which circumvents all sanity checks for interrupts which cannot have their affinity set from process context on X86 due to the way the X86 interrupt delivery works. It would be possible to make this work properly, but there is no point in doing so. If the interrupt is not yet started then the affinity setting has no effect and if it is started already then it is already assigned to an online CPU so there is no point to randomly move it to some other CPU. Just return EINVAL as the code has done before that change forever. - The new MSI quirk bit in the irq domain flags turned out to be already occupied, which escaped the author and the reviewers because the already in use bits were 0,6,2,3,4,5 listed in that order. That bit 6 was simply overlooked because the ordering was straight forward linear otherwise. So the new bit ended up being a duplicate. Fix it up by switching the oddball 6 to the obvious 1" * tag 'irq-urgent-2020-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: genirq/irqdomain: Make sure all irq domain flags are distinct genirq/proc: Reject invalid affinity masks (again)
2020-02-22Merge tag 's390-5.6-4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux Pull s390 fixes from Vasily Gorbik: - Remove ieee_emulation_warnings sysctl which is a dead code. - Avoid triggering rebuild of the kernel during make install. - Enable protected virtualization guest support in default configs. - Fix cio_ignore seq_file .next function to increase position index. And use kobj_to_dev instead of container_of in cio code. - Fix storage block address lists to contain absolute addresses in qdio code. - Few clang warnings and spelling fixes. * tag 's390-5.6-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: s390/qdio: fill SBALEs with absolute addresses s390/qdio: fill SL with absolute addresses s390: remove obsolete ieee_emulation_warnings s390: make 'install' not depend on vmlinux s390/kaslr: Fix casts in get_random s390/mm: Explicitly compare PAGE_DEFAULT_KEY against zero in storage_key_init_range s390/pkey/zcrypt: spelling s/crytp/crypt/ s390/cio: use kobj_to_dev() API s390/defconfig: enable CONFIG_PROTECTED_VIRTUALIZATION_GUEST s390/cio: cio_ignore_proc_seq_next should increase position index
2020-02-21Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-nextDavid S. Miller
Daniel Borkmann says: ==================== pull-request: bpf-next 2020-02-21 The following pull-request contains BPF updates for your *net-next* tree. We've added 25 non-merge commits during the last 4 day(s) which contain a total of 33 files changed, 2433 insertions(+), 161 deletions(-). The main changes are: 1) Allow for adding TCP listen sockets into sock_map/hash so they can be used with reuseport BPF programs, from Jakub Sitnicki. 2) Add a new bpf_program__set_attach_target() helper for adding libbpf support to specify the tracepoint/function dynamically, from Eelco Chaudron. 3) Add bpf_read_branch_records() BPF helper which helps use cases like profile guided optimizations, from Daniel Xu. 4) Enable bpf_perf_event_read_value() in all tracing programs, from Song Liu. 5) Relax BTF mandatory check if only used for libbpf itself e.g. to process BTF defined maps, from Andrii Nakryiko. 6) Move BPF selftests -mcpu compilation attribute from 'probe' to 'v3' as it has been observed that former fails in envs with low memlock, from Yonghong Song. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-21net: Generate reuseport group ID on group creationJakub Sitnicki
Commit 736b46027eb4 ("net: Add ID (if needed) to sock_reuseport and expose reuseport_lock") has introduced lazy generation of reuseport group IDs that survive group resize. By comparing the identifier we check if BPF reuseport program is not trying to select a socket from a BPF map that belongs to a different reuseport group than the one the packet is for. Because SOCKARRAY used to be the only BPF map type that can be used with reuseport BPF, it was possible to delay the generation of reuseport group ID until a socket from the group was inserted into BPF map for the first time. Now that SOCK{MAP,HASH} can be used with reuseport BPF we have two options, either generate the reuseport ID on map update, like SOCKARRAY does, or allocate an ID from the start when reuseport group gets created. This patch takes the latter approach to keep sockmap free of calls into reuseport code. This streamlines the reuseport_id access as its lifetime now matches the longevity of reuseport object. The cost of this simplification, however, is that we allocate reuseport IDs for all SO_REUSEPORT users. Even those that don't use SOCKARRAY in their setups. With the way identifiers are currently generated, we can have at most S32_MAX reuseport groups, which hopefully is sufficient. If we ever get close to the limit, we can switch an u64 counter like sk_cookie. Another change is that we now always call into SOCKARRAY logic to unlink the socket from the map when unhashing or closing the socket. Previously we did it only when at least one socket from the group was in a BPF map. It is worth noting that this doesn't conflict with sockmap tear-down in case a socket is in a SOCK{MAP,HASH} and belongs to a reuseport group. sockmap tear-down happens first: prot->unhash `- tcp_bpf_unhash |- tcp_bpf_remove | `- while (sk_psock_link_pop(psock)) | `- sk_psock_unlink | `- sock_map_delete_from_link | `- __sock_map_delete | `- sock_map_unref | `- sk_psock_put | `- sk_psock_drop | `- rcu_assign_sk_user_data(sk, NULL) `- inet_unhash `- reuseport_detach_sock `- bpf_sk_reuseport_detach `- WRITE_ONCE(sk->sk_user_data, NULL) Suggested-by: Martin Lau <kafai@fb.com> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200218171023.844439-10-jakub@cloudflare.com
2020-02-21bpf: Allow selecting reuseport socket from a SOCKMAP/SOCKHASHJakub Sitnicki
SOCKMAP & SOCKHASH now support storing references to listening sockets. Nothing keeps us from using these map types a collection of sockets to select from in BPF reuseport programs. Whitelist the map types with the bpf_sk_select_reuseport helper. The restriction that the socket has to be a member of a reuseport group still applies. Sockets in SOCKMAP/SOCKHASH that don't have sk_reuseport_cb set are not a valid target and we signal it with -EINVAL. The main benefit from this change is that, in contrast to REUSEPORT_SOCKARRAY, SOCK{MAP,HASH} don't impose a restriction that a listening socket can be just one BPF map at the same time. Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200218171023.844439-9-jakub@cloudflare.com
2020-02-21Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netLinus Torvalds
Pull networking fixes from David Miller: 1) Limit xt_hashlimit hash table size to avoid OOM or hung tasks, from Cong Wang. 2) Fix deadlock in xsk by publishing global consumer pointers when NAPI is finished, from Magnus Karlsson. 3) Set table field properly to RT_TABLE_COMPAT when necessary, from Jethro Beekman. 4) NLA_STRING attributes are not necessary NULL terminated, deal wiht that in IFLA_ALT_IFNAME. From Eric Dumazet. 5) Fix checksum handling in atlantic driver, from Dmitry Bezrukov. 6) Handle mtu==0 devices properly in wireguard, from Jason A. Donenfeld. 7) Fix several lockdep warnings in bonding, from Taehee Yoo. 8) Fix cls_flower port blocking, from Jason Baron. 9) Sanitize internal map names in libbpf, from Toke Høiland-Jørgensen. 10) Fix RDMA race in qede driver, from Michal Kalderon. 11) Fix several false lockdep warnings by adding conditions to list_for_each_entry_rcu(), from Madhuparna Bhowmik. 12) Fix sleep in atomic in mlx5 driver, from Huy Nguyen. 13) Fix potential deadlock in bpf_map_do_batch(), from Yonghong Song. 14) Hey, variables declared in switch statement before any case statements are not initialized. I learn something every day. Get rids of this stuff in several parts of the networking, from Kees Cook. * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (99 commits) bnxt_en: Issue PCIe FLR in kdump kernel to cleanup pending DMAs. bnxt_en: Improve device shutdown method. net: netlink: cap max groups which will be considered in netlink_bind() net: thunderx: workaround BGX TX Underflow issue ionic: fix fw_status read net: disable BRIDGE_NETFILTER by default net: macb: Properly handle phylink on at91rm9200 s390/qeth: fix off-by-one in RX copybreak check s390/qeth: don't warn for napi with 0 budget s390/qeth: vnicc Fix EOPNOTSUPP precedence openvswitch: Distribute switch variables for initialization net: ip6_gre: Distribute switch variables for initialization net: core: Distribute switch variables for initialization udp: rehash on disconnect net/tls: Fix to avoid gettig invalid tls record bpf: Fix a potential deadlock with bpf_map_do_batch bpf: Do not grab the bucket spinlock by default on htab batch ops ice: Wait for VF to be reset/ready before configuration ice: Don't tell the OS that link is going down ice: Don't reject odd values of usecs set by user ...
2020-02-21y2038: remove unused time32 interfacesArnd Bergmann
No users remain, so kill these off before we grow new ones. Link: http://lkml.kernel.org/r/20200110154232.4104492-3-arnd@arndb.de Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Deepa Dinamani <deepa.kernel@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-02-20bootconfig: Set CONFIG_BOOT_CONFIG=n by defaultMasami Hiramatsu
Set CONFIG_BOOT_CONFIG=n by default. This also warns user if CONFIG_BOOT_CONFIG=n but "bootconfig" is given in the kernel command line. Link: http://lkml.kernel.org/r/158220111291.26565.9036889083940367969.stgit@devnote2 Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-20tracing: Clear trace_state when starting traceMasami Hiramatsu
Clear trace_state data structure when starting trace in __synth_event_trace_start() internal function. Currently trace_state is initialized only in the synth_event_trace_start() API, but the trace_state in synth_event_trace() and synth_event_trace_array() are on the stack without initialization. This means those APIs will see wrong parameters and wil skip closing process in __synth_event_trace_end() because trace_state->disabled may be !0. Link: http://lkml.kernel.org/r/158193315899.8868.1781259176894639952.stgit@devnote2 Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-20tracing: Disable trace_printk() on post poned testsSteven Rostedt (VMware)
The tracing seftests checks various aspects of the tracing infrastructure, and one is filtering. If trace_printk() is active during a self test, it can cause the filtering to fail, which will disable that part of the trace. To keep the selftests from failing because of trace_printk() calls, trace_printk() checks the variable tracing_selftest_running, and if set, it does not write to the tracing buffer. As some tracers were registered earlier in boot, the selftest they triggered would fail because not all the infrastructure was set up for the full selftest. Thus, some of the tests were post poned to when their infrastructure was ready (namely file system code). The postpone code did not set the tracing_seftest_running variable, and could fail if a trace_printk() was added and executed during their run. Cc: stable@vger.kernel.org Fixes: 9afecfbb95198 ("tracing: Postpone tracer start-up tests till the system is more robust") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-20tracing: Have synthetic event test use raw_smp_processor_id()Steven Rostedt (VMware)
The test code that tests synthetic event creation pushes in as one of its test fields the current CPU using "smp_processor_id()". As this is just something to see if the value is correctly passed in, and the actual CPU used does not matter, use raw_smp_processor_id(), otherwise with debug preemption enabled, a warning happens as the smp_processor_id() is called without preemption enabled. Link: http://lkml.kernel.org/r/20200220162950.35162579@gandalf.local.home Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-20tracing: Fix number printing bug in print_synth_event()Tom Zanussi
Fix a varargs-related bug in print_synth_event() which resulted in strange output and oopses on 32-bit x86 systems. The problem is that trace_seq_printf() expects the varargs to match the format string, but print_synth_event() was always passing u64 values regardless. This results in unspecified behavior when unpacking with va_arg() in trace_seq_printf(). Add a function that takes the size into account when calling trace_seq_printf(). Before: modprobe-1731 [003] .... 919.039758: gen_synth_test: next_pid_field=777(null)next_comm_field=hula hoops ts_ns=1000000 ts_ms=1000 cpu=3(null)my_string_field=thneed my_int_field=598(null) After: insmod-1136 [001] .... 36.634590: gen_synth_test: next_pid_field=777 next_comm_field=hula hoops ts_ns=1000000 ts_ms=1000 cpu=1 my_string_field=thneed my_int_field=598 Link: http://lkml.kernel.org/r/a9b59eb515dbbd7d4abe53b347dccf7a8e285657.1581720155.git.zanussi@kernel.org Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-20tracing: Check that number of vals matches number of synth event fieldsTom Zanussi
Commit 7276531d4036('tracing: Consolidate trace() functions') inadvertently dropped the synth_event_trace() and synth_event_trace_array() checks that verify the number of values passed in matches the number of fields in the synthetic event being traced, so add them back. Link: http://lkml.kernel.org/r/32819cac708714693669e0dfe10fe9d935e94a16.1581720155.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-20tracing: Make synth_event trace functions endian-correctTom Zanussi
synth_event_trace(), synth_event_trace_array() and __synth_event_add_val() write directly into the trace buffer and need to take endianness into account, like trace_event_raw_event_synth() does. Link: http://lkml.kernel.org/r/2011354355e405af9c9d28abba430d1f5ff7771a.1581720155.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-20tracing: Make sure synth_event_trace() example always uses u64Tom Zanussi
synth_event_trace() is the varargs version of synth_event_trace_array(), which takes an array of u64, as do synth_event_add_val() et al. To not only be consistent with those, but also to address the fact that synth_event_trace() expects every arg to be of the same type since it doesn't also pass in e.g. a format string, the caller needs to make sure all args are of the same type, u64. u64 is used because it needs to accomodate the largest type available in synthetic events, which is u64. This fixes the bug reported by the kernel test robot/Rong Chen. Link: https://lore.kernel.org/lkml/20200212113444.GS12867@shao2-debian/ Link: http://lkml.kernel.org/r/894c4e955558b521210ee0642ba194a9e603354c.1581720155.git.zanussi@kernel.org Fixes: 9fe41efaca084 ("tracing: Add synth event generation test module") Reported-by: kernel test robot <rong.a.chen@intel.com> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-02-19Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpfDavid S. Miller
Alexei Starovoitov says: ==================== pull-request: bpf 2020-02-19 The following pull-request contains BPF updates for your *net* tree. We've added 10 non-merge commits during the last 10 day(s) which contain a total of 10 files changed, 93 insertions(+), 31 deletions(-). The main changes are: 1) batched bpf hashtab fixes from Brian and Yonghong. 2) various selftests and libbpf fixes. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-19bpf: Fix a potential deadlock with bpf_map_do_batchYonghong Song
Commit 057996380a42 ("bpf: Add batch ops to all htab bpf map") added lookup_and_delete batch operation for hash table. The current implementation has bpf_lru_push_free() inside the bucket lock, which may cause a deadlock. syzbot reports: -> #2 (&htab->buckets[i].lock#2){....}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 htab_lru_map_delete_node+0xce/0x2f0 kernel/bpf/hashtab.c:593 __bpf_lru_list_shrink_inactive kernel/bpf/bpf_lru_list.c:220 [inline] __bpf_lru_list_shrink+0xf9/0x470 kernel/bpf/bpf_lru_list.c:266 bpf_lru_list_pop_free_to_local kernel/bpf/bpf_lru_list.c:340 [inline] bpf_common_lru_pop_free kernel/bpf/bpf_lru_list.c:447 [inline] bpf_lru_pop_free+0x87c/0x1670 kernel/bpf/bpf_lru_list.c:499 prealloc_lru_pop+0x2c/0xa0 kernel/bpf/hashtab.c:132 __htab_lru_percpu_map_update_elem+0x67e/0xa90 kernel/bpf/hashtab.c:1069 bpf_percpu_hash_update+0x16e/0x210 kernel/bpf/hashtab.c:1585 bpf_map_update_value.isra.0+0x2d7/0x8e0 kernel/bpf/syscall.c:181 generic_map_update_batch+0x41f/0x610 kernel/bpf/syscall.c:1319 bpf_map_do_batch+0x3f5/0x510 kernel/bpf/syscall.c:3348 __do_sys_bpf+0x9b7/0x41e0 kernel/bpf/syscall.c:3460 __se_sys_bpf kernel/bpf/syscall.c:3355 [inline] __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:3355 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&loc_l->lock){....}: check_prev_add kernel/locking/lockdep.c:2475 [inline] check_prevs_add kernel/locking/lockdep.c:2580 [inline] validate_chain kernel/locking/lockdep.c:2970 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3954 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4484 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 bpf_common_lru_push_free kernel/bpf/bpf_lru_list.c:516 [inline] bpf_lru_push_free+0x250/0x5b0 kernel/bpf/bpf_lru_list.c:555 __htab_map_lookup_and_delete_batch+0x8d4/0x1540 kernel/bpf/hashtab.c:1374 htab_lru_map_lookup_and_delete_batch+0x34/0x40 kernel/bpf/hashtab.c:1491 bpf_map_do_batch+0x3f5/0x510 kernel/bpf/syscall.c:3348 __do_sys_bpf+0x1f7d/0x41e0 kernel/bpf/syscall.c:3456 __se_sys_bpf kernel/bpf/syscall.c:3355 [inline] __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:3355 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Possible unsafe locking scenario: CPU0 CPU2 ---- ---- lock(&htab->buckets[i].lock#2); lock(&l->lock); lock(&htab->buckets[i].lock#2); lock(&loc_l->lock); *** DEADLOCK *** To fix the issue, for htab_lru_map_lookup_and_delete_batch() in CPU0, let us do bpf_lru_push_free() out of the htab bucket lock. This can avoid the above deadlock scenario. Fixes: 057996380a42 ("bpf: Add batch ops to all htab bpf map") Reported-by: syzbot+a38ff3d9356388f2fb83@syzkaller.appspotmail.com Reported-by: syzbot+122b5421d14e68f29cd1@syzkaller.appspotmail.com Suggested-by: Hillf Danton <hdanton@sina.com> Suggested-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com> Acked-by: Brian Vazquez <brianvv@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200219234757.3544014-1-yhs@fb.com