- 28 Feb, 2020 3 commits
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Martin KaFai Lau authored
The INET_DIAG_REQ_BYTECODE nlattr is currently re-found every time when the "dump()" is re-started. In a latter patch, it will also need to parse the new INET_DIAG_REQ_SK_BPF_STORAGES nlattr to learn the map_fds. Thus, this patch takes this chance to store the parsed nlattr in cb->data during the "start" time of a dump. By doing this, the "bc" argument also becomes unnecessary and is removed. Also, the two copies of the INET_DIAG_REQ_BYTECODE parsing-audit logic between compat/current version can be consolidated to one. 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/20200225230415.1975555-1-kafai@fb.com
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Martin KaFai Lau authored
In a latter patch, there is a need to update "cb->min_dump_alloc" in inet_sk_diag_fill() as it learns the diffierent bpf_sk_storages stored in a sk while dumping all sk(s) (e.g. tcp_hashinfo). The inet_sk_diag_fill() currently does not take the "cb" as an argument. One of the reason is inet_sk_diag_fill() is used by both dump_one() and dump() (which belong to the "struct inet_diag_handler". The dump_one() interface does not pass the "cb" along. This patch is to make dump_one() pass a "cb". The "cb" is created in inet_diag_cmd_exact(). The "nlh" and "in_skb" are stored in "cb" as the dump() interface does. The total number of args in inet_sk_diag_fill() is also cut from 10 to 7 and that helps many callers to pass fewer args. In particular, "struct user_namespace *user_ns", "u32 pid", and "u32 seq" can be replaced by accessing "cb->nlh" and "cb->skb". A similar argument reduction is also made to inet_twsk_diag_fill() and inet_req_diag_fill(). inet_csk_diag_dump() and inet_csk_diag_fill() are also removed. They are mostly equivalent to inet_sk_diag_fill(). Their repeated usages are very limited. Thus, inet_sk_diag_fill() is directly used in those occasions. Signed-off-by:
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Gustavo A. R. Silva authored
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 76497732 ("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:
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- 26 Feb, 2020 8 commits
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Daniel Borkmann authored
Michal Rostecki says: ==================== Feature probes in bpftool related to bpf_probe_write_user and bpf_trace_printk helpers emit dmesg warnings which might be confusing for people running bpftool on production environments. This patch series addresses that by filtering them out by default and introducing the new positional argument "full" which enables all available probes. The main motivation behind those changes is ability the fact that some probes (for example those related to "trace" or "write_user" helpers) emit dmesg messages which might be confusing for people who are running on production environments. For details see the Cilium issue[0]. v1 -> v2: - Do not expose regex filters to users, keep filtering logic internal, expose only the "full" option for including probes which emit dmesg warnings. v2 -> v3: - Do not use regex for filtering out probes, use function IDs directly. - Fix bash completion - in v2 only "prefix" was proposed after "macros", "dev" and "kernel" were not. - Rephrase the man page paragraph, highlight helper function names. - Remove tests which parse the plain output of bpftool (except the header/macros test), focus on testing JSON output instead. - Add test which compares the output with and without "full" option. v3 -> v4: - Use enum to check for helper functions. - Make selftests compatible with older versions of Python 3.x than 3.7. [0] https://github.com/cilium/cilium/issues/10048 ==================== Signed-off-by:
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Michal Rostecki authored
Add Python module with tests for "bpftool feature" command, which mainly checks whether the "full" option is working properly. Signed-off-by:
Michal Rostecki <mrostecki@opensuse.org> Signed-off-by:
Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20200226165941.6379-6-mrostecki@opensuse.org
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Michal Rostecki authored
Update bash completion for "bpftool feature" command with the new argument: "full". Signed-off-by:
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Michal Rostecki authored
Update documentation of "bpftool feature" command with information about new arguments: "full". Signed-off-by:
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Michal Rostecki authored
Probes related to bpf_probe_write_user and bpf_trace_printk helpers emit dmesg warnings which might be confusing for people running bpftool on production environments. This change filters them out by default and introduces the new positional argument "full" which enables all available probes. Signed-off-by:
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Michal Rostecki authored
Remove all calls of print_end_then_start_section function and for loops out from the do_probe function. Instead, provide separate functions for each section (like i.e. section_helpers) which are called in do_probe. This change is motivated by better readability. Signed-off-by:
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Andrey Ignatov authored
Add support for prog types that were added to kernel but not present in bpftool yet: struct_ops, tracing, ext prog types and corresponding section names. Before: # bpftool p l ... 184: type 26 name test_subprog3 tag dda135a7dc0daf54 gpl loaded_at 2020-02-25T13:28:33-0800 uid 0 xlated 112B jited 103B memlock 4096B map_ids 136 btf_id 85 185: type 28 name new_get_skb_len tag d2de5b87d8e5dc49 gpl loaded_at 2020-02-25T13:28:33-0800 uid 0 xlated 72B jited 69B memlock 4096B map_ids 136 btf_id 85 After: # bpftool p l ... 184: tracing name test_subprog3 tag dda135a7dc0daf54 gpl loaded_at 2020-02-25T13:28:33-0800 uid 0 xlated 112B jited 103B memlock 4096B map_ids 136 btf_id 85 185: ext name new_get_skb_len tag d2de5b87d8e5dc49 gpl loaded_at 2020-02-25T13:28:33-0800 uid 0 xlated 72B jited 69B memlock 4096B map_ids 136 btf_id 85 Signed-off-by:Andrey Ignatov <rdna@fb.com> Signed-off-by:
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Scott Branden authored
Change "/usr/bin/python3" to "/usr/bin/env python3" for more portable solution in bpf_helpers_doc.py. Signed-off-by:
Scott Branden <scott.branden@broadcom.com> Signed-off-by:
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- 25 Feb, 2020 29 commits
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Yuya Kusakabe authored
Implement support for transferring XDP meta data into skb for virtio_net driver; before calling into the program, xdp.data_meta points to xdp.data, where on program return with pass verdict, we call into skb_metadata_set(). Tested with the script at https://github.com/higebu/virtio_net-xdp-metadata-test. Signed-off-by:
Yuya Kusakabe <yuya.kusakabe@gmail.com> Signed-off-by:
Jason Wang <jasowang@redhat.com> Acked-by:
Michael S. Tsirkin <mst@redhat.com> Link: https://lore.kernel.org/bpf/20200225033212.437563-2-yuya.kusakabe@gmail.com
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Yuya Kusakabe authored
We do not want to care about the vnet header in receive_small() if XDP is loaded, since we can not know whether or not the packet is modified by XDP. Fixes: f6b10209 ("virtio-net: switch to use build_skb() for small buffer") Signed-off-by:
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Andrii Nakryiko authored
Due to various bugs in tests clean up code (usually), if host system is misconfigured, it happens that test_progs will just crash in the middle of running a test with little to no indication of where and why the crash happened. For cases where coredump is not readily available (e.g., inside a CI), it's very helpful to have a stack trace, which lead to crash, to be printed out. This change adds a signal handler that will capture and print out symbolized backtrace: $ sudo ./test_progs -t mmap test_mmap:PASS:skel_open_and_load 0 nsec test_mmap:PASS:bss_mmap 0 nsec test_mmap:PASS:data_mmap 0 nsec Caught signal #11! Stack trace: ./test_progs(crash_handler+0x18)[0x42a888] /lib64/libpthread.so.0(+0xf5d0)[0x7f2aab5175d0] ./test_progs(test_mmap+0x3c0)[0x41f0a0] ./test_progs(main+0x160)[0x407d10] /lib64/libc.so.6(__libc_start_main+0xf5)[0x7f2aab15d3d5] ./test_progs[0x407ebc] [1] 1988412 segmentation fault (core dumped) sudo ./test_progs -t mmap Unfortunately, glibc's symbolization support is unable to symbolize static functions, only global ones will be present in stack trace. But it's still a step forward without adding extra libraries to get a better symbolization. Signed-off-by:
Andrii Nakryiko <andriin@fb.com> Signed-off-by:
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Jakub Sitnicki authored
Currently we run SYN cookies test for all socket types and mark the test as skipped if socket type is not compatible. This causes confusion because skipped test might indicate a problem with the testing environment. Instead, run the test only for the socket type which supports SYN cookies. Also, switch to using designated initializers when setting up tests, so that we can tweak only some test parameters, leaving the rest initialized to default values. Fixes: eecd618b ("selftests/bpf: Mark SYN cookie test skipped for UDP sockets") Reported-by:
Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by:
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Jakub Sitnicki authored
SOCKMAP and SOCKHASH map types can be used with reuseport BPF programs but don't support yet storing UDP sockets. Instead of marking UDP tests with SOCK{MAP,HASH} as skipped, don't run them at all. Skipped test might signal that the test environment is not suitable for running the test, while in reality the functionality is not implemented in the kernel yet. Before: sh# ./test_progs -t select_reuseport … #40 select_reuseport:OK Summary: 1/126 PASSED, 30 SKIPPED, 0 FAILED After: sh# ./test_progs -t select_reuseport … #40 select_reuseport:OK Summary: 1/98 PASSED, 2 SKIPPED, 0 FAILED The remaining two skipped tests are SYN cookies tests, which will be addressed in the subsequent patch. Fixes: 11318ba8 ("selftests/bpf: Extend SK_REUSEPORT tests to cover SOCKMAP/SOCKHASH") Reported-by: -
Alexei Starovoitov authored
Thomas Gleixner says: ==================== This is the third version of the BPF/RT patch set which makes both coexist nicely. The long explanation can be found in the cover letter of the V1 submission: https://lore.kernel.org/r/20200214133917.304937432@linutronix.de V2 is here: https://lore.kernel.org/r/20200220204517.863202864@linutronix.de The following changes vs. V2 have been made: - Rebased to bpf-next, adjusted to the lock changes in the hashmap code. - Split the preallocation enforcement patch for instrumentation type BPF programs into two pieces: 1) Emit a one-time warning on !RT kernels when any instrumentation type BPF program uses run-time allocation. Emit also a corresponding warning in the verifier log. But allow the program to run for backward compatibility sake. After a grace period this should be enforced. 2) On RT reject such programs because on RT the memory allocator cannot be called from truly atomic contexts. - Fixed the fallout from V2 as reported by Alexei and 0-day - Removed the redundant preempt_disable() from trace_call_bpf() - Removed the unused export of trace_call_bpf() ==================== Signed-off-by:
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David Miller authored
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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
The places which need to prevent the execution of trace type BPF programs to prevent deadlocks on the hash bucket lock do this open coded. Provide two inline functions, bpf_disable/enable_instrumentation() to replace these open coded protection constructs. Use migrate_disable/enable() instead of preempt_disable/enable() right away so this works on RT enabled kernels. On a !RT kernel migrate_disable / enable() are mapped to preempt_disable/enable(). These helpers use this_cpu_inc/dec() instead of __this_cpu_inc/dec() on an RT enabled kernel because migrate disabled regions are preemptible and preemption might hit in the middle of a RMW operation which can lead to inconsistent state. Signed-off-by:
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David Miller authored
Replace the preemption disable/enable with migrate_disable/enable() to reflect the actual requirement and to allow PREEMPT_RT to substitute it with an actual migration disable mechanism which does not disable preemption. Including the code paths that go via __bpf_prog_run_save_cb(). Signed-off-by:
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David Miller authored
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:
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David Miller authored
Replace the preemption disable/enable with migrate_disable/enable() to reflect the actual requirement and to allow PREEMPT_RT to substitute it with an actual migration disable mechanism which does not disable preemption. [ tglx: Switched it over to migrate disable ] Signed-off-by:
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David Miller authored
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:
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Thomas Gleixner authored
As already discussed in the previous change which introduced BPF_RUN_PROG_PIN_ON_CPU() BPF only requires to disable migration to guarantee per CPUness. If RT substitutes the preempt disable based migration protection then the cant_sleep() check will obviously trigger as preemption is not disabled. Replace it by cant_migrate() which maps to cant_sleep() on a non RT kernel and will verify that migration is disabled on a full RT kernel. Signed-off-by:
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Thomas Gleixner authored
BPF programs require to run on one CPU to completion as they use per CPU storage, but according to Alexei they don't need reentrancy protection as obviously BPF programs running in thread context can always be 'preempted' by hard and soft interrupts and instrumentation and the same program can run concurrently on a different CPU. The currently used mechanism to ensure CPUness is to wrap the invocation into a preempt_disable/enable() pair. Disabling preemption is also disabling migration for a task. preempt_disable/enable() is used because there is no explicit way to reliably disable only migration. Provide a separate macro to invoke a BPF program which can be used in migrateable task context. It wraps BPF_PROG_RUN() in a migrate_disable/enable() pair which maps on non RT enabled kernels to preempt_disable/enable(). On RT enabled kernels this merely disables migration. Both methods ensure that the invoked BPF program runs on one CPU to completion. Signed-off-by:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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Alexei Starovoitov authored
trace_call_bpf() no longer disables preemption on its own. All callers of this function has to do it explicitly. Signed-off-by:
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Thomas Gleixner authored
All callers are built in. No point to export this. Signed-off-by:
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Thomas Gleixner authored
__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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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Thomas Gleixner authored
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:
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