kernel/linux.git/include/linux/filter.h, branch v4.3.1

bpf: also show process name/pid in bpf_jit_dump

2015-07-30T18:13:21+00:00

It can be useful for testing to see the actual process/pid who is loading a given filter. I was running some BPF test program and noticed unusual filter loads from time to time, triggered by some other application in the background. bpf_jit_disasm is still working after this change. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

bpf: provide helper that indicates eBPF was migrated

2015-07-30T18:13:20+00:00

During recent discussions we had with Michael, we found that it would be useful to have an indicator that tells the JIT that an eBPF program had been migrated from classic instructions into eBPF instructions, as only in that case A and X need to be cleared in the prologue. Such eBPF programs do not set a particular type, but all have BPF_PROG_TYPE_UNSPEC. Thus, introduce a small helper for cde66c2d88da ("s390/bpf: Only clear A and X for converted BPF programs") and possibly others in future. Signed-off-by: Daniel Borkmann Cc: Michael Holzheu Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

bpf: introduce bpf_skb_vlan_push/pop() helpers

2015-07-21T03:52:31+00:00

Allow eBPF programs attached to TC qdiscs call skb_vlan_push/pop via helper functions. These functions may change skb->data/hlen which are cached by some JITs to improve performance of ld_abs/ld_ind instructions. Therefore JITs need to recognize bpf_skb_vlan_push/pop() calls, re-compute header len and re-cache skb->data/hlen back into cpu registers. Note, skb->data/hlen are not directly accessible from the programs, so any changes to skb->data done either by these helpers or by other TC actions are safe. eBPF JIT supported by three architectures: - arm64 JIT is using bpf_load_pointer() without caching, so it's ok as-is. - x64 JIT re-caches skb->data/hlen unconditionally after vlan_push/pop calls (experiments showed that conditional re-caching is slower). - s390 JIT falls back to interpreter for now when bpf_skb_vlan_push() is present in the program (re-caching is tbd). These helpers allow more scalable handling of vlan from the programs. Instead of creating thousands of vlan netdevs on top of eth0 and attaching TC+ingress+bpf to all of them, the program can be attached to eth0 directly and manipulate vlans as necessary. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller

bpf: allow bpf programs to tail-call other bpf programs

2015-05-21T21:07:59+00:00

introduce bpf_tail_call(ctx, &jmp_table, index) helper function which can be used from BPF programs like: int bpf_prog(struct pt_regs *ctx) { ... bpf_tail_call(ctx, &jmp_table, index); ... } that is roughly equivalent to: int bpf_prog(struct pt_regs *ctx) { ... if (jmp_table[index]) return (*jmp_table[index])(ctx); ... } The important detail that it's not a normal call, but a tail call. The kernel stack is precious, so this helper reuses the current stack frame and jumps into another BPF program without adding extra call frame. It's trivially done in interpreter and a bit trickier in JITs. In case of x64 JIT the bigger part of generated assembler prologue is common for all programs, so it is simply skipped while jumping. Other JITs can do similar prologue-skipping optimization or do stack unwind before jumping into the next program. bpf_tail_call() arguments: ctx - context pointer jmp_table - one of BPF_MAP_TYPE_PROG_ARRAY maps used as the jump table index - index in the jump table Since all BPF programs are idenitified by file descriptor, user space need to populate the jmp_table with FDs of other BPF programs. If jmp_table[index] is empty the bpf_tail_call() doesn't jump anywhere and program execution continues as normal. New BPF_MAP_TYPE_PROG_ARRAY map type is introduced so that user space can populate this jmp_table array with FDs of other bpf programs. Programs can share the same jmp_table array or use multiple jmp_tables. The chain of tail calls can form unpredictable dynamic loops therefore tail_call_cnt is used to limit the number of calls and currently is set to 32. Use cases: Acked-by: Daniel Borkmann ========== - simplify complex programs by splitting them into a sequence of small programs - dispatch routine For tracing and future seccomp the program may be triggered on all system calls, but processing of syscall arguments will be different. It's more efficient to implement them as: int syscall_entry(struct seccomp_data *ctx) { bpf_tail_call(ctx, &syscall_jmp_table, ctx->nr /* syscall number */); ... default: process unknown syscall ... } int sys_write_event(struct seccomp_data *ctx) {...} int sys_read_event(struct seccomp_data *ctx) {...} syscall_jmp_table[__NR_write] = sys_write_event; syscall_jmp_table[__NR_read] = sys_read_event; For networking the program may call into different parsers depending on packet format, like: int packet_parser(struct __sk_buff *skb) { ... parse L2, L3 here ... __u8 ipproto = load_byte(skb, ... offsetof(struct iphdr, protocol)); bpf_tail_call(skb, &ipproto_jmp_table, ipproto); ... default: process unknown protocol ... } int parse_tcp(struct __sk_buff *skb) {...} int parse_udp(struct __sk_buff *skb) {...} ipproto_jmp_table[IPPROTO_TCP] = parse_tcp; ipproto_jmp_table[IPPROTO_UDP] = parse_udp; - for TC use case, bpf_tail_call() allows to implement reclassify-like logic - bpf_map_update_elem/delete calls into BPF_MAP_TYPE_PROG_ARRAY jump table are atomic, so user space can build chains of BPF programs on the fly Implementation details: ======================= - high performance of bpf_tail_call() is the goal. It could have been implemented without JIT changes as a wrapper on top of BPF_PROG_RUN() macro, but with two downsides: . all programs would have to pay performance penalty for this feature and tail call itself would be slower, since mandatory stack unwind, return, stack allocate would be done for every tailcall. . tailcall would be limited to programs running preempt_disabled, since generic 'void *ctx' doesn't have room for 'tail_call_cnt' and it would need to be either global per_cpu variable accessed by helper and by wrapper or global variable protected by locks. In this implementation x64 JIT bypasses stack unwind and jumps into the callee program after prologue. - bpf_prog_array_compatible() ensures that prog_type of callee and caller are the same and JITed/non-JITed flag is the same, since calling JITed program from non-JITed is invalid, since stack frames are different. Similarly calling kprobe type program from socket type program is invalid. - jump table is implemented as BPF_MAP_TYPE_PROG_ARRAY to reuse 'map' abstraction, its user space API and all of verifier logic. It's in the existing arraymap.c file, since several functions are shared with regular array map. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller

test_bpf: add tests related to BPF_MAXINSNS

2015-05-15T02:34:10+00:00

Couple of torture test cases related to the bug fixed in 0b59d8806a31 ("ARM: net: delegate filter to kernel interpreter when imm_offset() return value can't fit into 12bits."). I've added a helper to allocate and fill the insn space. Output on x86_64 from my laptop: test_bpf: #233 BPF_MAXINSNS: Maximum possible literals jited:0 7 PASS test_bpf: #234 BPF_MAXINSNS: Single literal jited:0 8 PASS test_bpf: #235 BPF_MAXINSNS: Run/add until end jited:0 11553 PASS test_bpf: #236 BPF_MAXINSNS: Too many instructions PASS test_bpf: #237 BPF_MAXINSNS: Very long jump jited:0 9 PASS test_bpf: #238 BPF_MAXINSNS: Ctx heavy transformations jited:0 20329 20398 PASS test_bpf: #239 BPF_MAXINSNS: Call heavy transformations jited:0 32178 32475 PASS test_bpf: #240 BPF_MAXINSNS: Jump heavy test jited:0 10518 PASS test_bpf: #233 BPF_MAXINSNS: Maximum possible literals jited:1 4 PASS test_bpf: #234 BPF_MAXINSNS: Single literal jited:1 4 PASS test_bpf: #235 BPF_MAXINSNS: Run/add until end jited:1 1625 PASS test_bpf: #236 BPF_MAXINSNS: Too many instructions PASS test_bpf: #237 BPF_MAXINSNS: Very long jump jited:1 8 PASS test_bpf: #238 BPF_MAXINSNS: Ctx heavy transformations jited:1 3301 3174 PASS test_bpf: #239 BPF_MAXINSNS: Call heavy transformations jited:1 24107 23491 PASS test_bpf: #240 BPF_MAXINSNS: Jump heavy test jited:1 8651 PASS Signed-off-by: Daniel Borkmann Cc: Alexei Starovoitov Cc: Nicolas Schichan Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

test_bpf: add 173 new testcases for eBPF

2015-05-13T03:15:25+00:00

add an exhaustive set of eBPF tests bringing total to: test_bpf: Summary: 233 PASSED, 0 FAILED, [0/226 JIT'ed] Signed-off-by: Michael Holzheu Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

seccomp, filter: add and use bpf_prog_create_from_user from seccomp

2015-05-09T21:35:05+00:00

Seccomp has always been a special candidate when it comes to preparation of its filters in seccomp_prepare_filter(). Due to the extra checks and filter rewrite it partially duplicates code and has BPF internals exposed. This patch adds a generic API inside the BPF code code that seccomp can use and thus keep it's filter preparation code minimal and better maintainable. The other side-effect is that now classic JITs can add seccomp support as well by only providing a BPF_LDX | BPF_W | BPF_ABS translation. Tested with seccomp and BPF test suites. Signed-off-by: Daniel Borkmann Cc: Nicolas Schichan Cc: Alexei Starovoitov Cc: Kees Cook Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

seccomp: simplify seccomp_prepare_filter and reuse bpf_prepare_filter

2015-05-09T21:35:05+00:00

Remove the calls to bpf_check_classic(), bpf_convert_filter() and bpf_migrate_runtime() and let bpf_prepare_filter() take care of that instead. seccomp_check_filter() is passed to bpf_prepare_filter() so that it gets called from there, after bpf_check_classic(). We can now remove exposure of two internal classic BPF functions previously used by seccomp. The export of bpf_check_classic() symbol, previously known as sk_chk_filter(), was there since pre git times, and no in-tree module was using it, therefore remove it. Joint work with Daniel Borkmann. Signed-off-by: Nicolas Schichan Signed-off-by: Daniel Borkmann Cc: Alexei Starovoitov Cc: Kees Cook Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

net: filter: add a callback to allow classic post-verifier transformations

2015-05-09T21:35:05+00:00

This is in preparation for use by the seccomp code, the rationale is not to duplicate additional code within the seccomp layer, but instead, have it abstracted and hidden within the classic BPF API. As an interim step, this now also makes bpf_prepare_filter() visible (not as exported symbol though), so that seccomp can reuse that code path instead of reimplementing it. Joint work with Daniel Borkmann. Signed-off-by: Nicolas Schichan Signed-off-by: Daniel Borkmann Cc: Alexei Starovoitov Cc: Kees Cook Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

filter: introduce SKF_AD_VLAN_TPID BPF extension

2015-03-24T19:25:15+00:00

If vlan offloading takes place then vlan header is removed from frame and its contents, both vlan_tci and vlan_proto, is available to user space via TPACKET interface. However, only vlan_tci can be used in BPF filters. This commit introduces a new BPF extension. It makes possible to load the value of vlan_proto (vlan TPID) to register A. Support for classic BPF and eBPF is being added, analogous to skb->protocol. Cc: Daniel Borkmann Cc: Alexei Starovoitov Cc: Jiri Pirko Signed-off-by: Michal Sekletar Acked-by: Daniel Borkmann Acked-by: Alexei Starovoitov Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller