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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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36bbef52c7
This work implements direct packet access for helpers and direct packet write in a similar fashion as already available for XDP types via commits4acf6c0b84
("bpf: enable direct packet data write for xdp progs") and6841de8b0d
("bpf: allow helpers access the packet directly"), and as a complementary feature to the already available direct packet read for tc (cls/act) programs. For enabling this, we need to introduce two helpers, bpf_skb_pull_data() and bpf_csum_update(). The first is generally needed for both, read and write, because they would otherwise only be limited to the current linear skb head. Usually, when the data_end test fails, programs just bail out, or, in the direct read case, use bpf_skb_load_bytes() as an alternative to overcome this limitation. If such data sits in non-linear parts, we can just pull them in once with the new helper, retest and eventually access them. At the same time, this also makes sure the skb is uncloned, which is, of course, a necessary condition for direct write. As this needs to be an invariant for the write part only, the verifier detects writes and adds a prologue that is calling bpf_skb_pull_data() to effectively unclone the skb from the very beginning in case it is indeed cloned. The heuristic makes use of a similar trick that was done in233577a220
("net: filter: constify detection of pkt_type_offset"). This comes at zero cost for other programs that do not use the direct write feature. Should a program use this feature only sparsely and has read access for the most parts with, for example, drop return codes, then such write action can be delegated to a tail called program for mitigating this cost of potential uncloning to a late point in time where it would have been paid similarly with the bpf_skb_store_bytes() as well. Advantage of direct write is that the writes are inlined whereas the helper cannot make any length assumptions and thus needs to generate a call to memcpy() also for small sizes, as well as cost of helper call itself with sanity checks are avoided. Plus, when direct read is already used, we don't need to cache or perform rechecks on the data boundaries (due to verifier invalidating previous checks for helpers that change skb->data), so more complex programs using rewrites can benefit from switching to direct read plus write. For direct packet access to helpers, we save the otherwise needed copy into a temp struct sitting on stack memory when use-case allows. Both facilities are enabled via may_access_direct_pkt_data() in verifier. For now, we limit this to map helpers and csum_diff, and can successively enable other helpers where we find it makes sense. Helpers that definitely cannot be allowed for this are those part of bpf_helper_changes_skb_data() since they can change underlying data, and those that write into memory as this could happen for packet typed args when still cloned. bpf_csum_update() helper accommodates for the fact that we need to fixup checksum_complete when using direct write instead of bpf_skb_store_bytes(), meaning the programs can use available helpers like bpf_csum_diff(), and implement csum_add(), csum_sub(), csum_block_add(), csum_block_sub() equivalents in eBPF together with the new helper. A usage example will be provided for iproute2's examples/bpf/ directory. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
329 lines
10 KiB
C
329 lines
10 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#ifndef _LINUX_BPF_H
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#define _LINUX_BPF_H 1
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#include <uapi/linux/bpf.h>
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#include <linux/workqueue.h>
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#include <linux/file.h>
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#include <linux/percpu.h>
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#include <linux/err.h>
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struct perf_event;
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struct bpf_map;
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/* map is generic key/value storage optionally accesible by eBPF programs */
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struct bpf_map_ops {
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/* funcs callable from userspace (via syscall) */
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struct bpf_map *(*map_alloc)(union bpf_attr *attr);
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void (*map_release)(struct bpf_map *map, struct file *map_file);
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void (*map_free)(struct bpf_map *map);
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int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
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/* funcs callable from userspace and from eBPF programs */
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void *(*map_lookup_elem)(struct bpf_map *map, void *key);
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int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
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int (*map_delete_elem)(struct bpf_map *map, void *key);
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/* funcs called by prog_array and perf_event_array map */
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void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file,
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int fd);
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void (*map_fd_put_ptr)(void *ptr);
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};
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struct bpf_map {
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atomic_t refcnt;
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enum bpf_map_type map_type;
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u32 key_size;
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u32 value_size;
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u32 max_entries;
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u32 map_flags;
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u32 pages;
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struct user_struct *user;
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const struct bpf_map_ops *ops;
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struct work_struct work;
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atomic_t usercnt;
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};
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struct bpf_map_type_list {
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struct list_head list_node;
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const struct bpf_map_ops *ops;
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enum bpf_map_type type;
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};
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/* function argument constraints */
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enum bpf_arg_type {
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ARG_DONTCARE = 0, /* unused argument in helper function */
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/* the following constraints used to prototype
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* bpf_map_lookup/update/delete_elem() functions
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*/
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ARG_CONST_MAP_PTR, /* const argument used as pointer to bpf_map */
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ARG_PTR_TO_MAP_KEY, /* pointer to stack used as map key */
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ARG_PTR_TO_MAP_VALUE, /* pointer to stack used as map value */
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/* the following constraints used to prototype bpf_memcmp() and other
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* functions that access data on eBPF program stack
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*/
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ARG_PTR_TO_STACK, /* any pointer to eBPF program stack */
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ARG_PTR_TO_RAW_STACK, /* any pointer to eBPF program stack, area does not
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* need to be initialized, helper function must fill
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* all bytes or clear them in error case.
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*/
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ARG_CONST_STACK_SIZE, /* number of bytes accessed from stack */
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ARG_CONST_STACK_SIZE_OR_ZERO, /* number of bytes accessed from stack or 0 */
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ARG_PTR_TO_CTX, /* pointer to context */
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ARG_ANYTHING, /* any (initialized) argument is ok */
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};
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/* type of values returned from helper functions */
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enum bpf_return_type {
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RET_INTEGER, /* function returns integer */
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RET_VOID, /* function doesn't return anything */
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RET_PTR_TO_MAP_VALUE_OR_NULL, /* returns a pointer to map elem value or NULL */
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};
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/* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
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* to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
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* instructions after verifying
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*/
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struct bpf_func_proto {
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u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
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bool gpl_only;
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bool pkt_access;
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enum bpf_return_type ret_type;
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enum bpf_arg_type arg1_type;
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enum bpf_arg_type arg2_type;
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enum bpf_arg_type arg3_type;
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enum bpf_arg_type arg4_type;
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enum bpf_arg_type arg5_type;
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};
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/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
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* the first argument to eBPF programs.
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* For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
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*/
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struct bpf_context;
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enum bpf_access_type {
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BPF_READ = 1,
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BPF_WRITE = 2
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};
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/* types of values stored in eBPF registers */
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enum bpf_reg_type {
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NOT_INIT = 0, /* nothing was written into register */
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UNKNOWN_VALUE, /* reg doesn't contain a valid pointer */
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PTR_TO_CTX, /* reg points to bpf_context */
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CONST_PTR_TO_MAP, /* reg points to struct bpf_map */
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PTR_TO_MAP_VALUE, /* reg points to map element value */
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PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
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FRAME_PTR, /* reg == frame_pointer */
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PTR_TO_STACK, /* reg == frame_pointer + imm */
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CONST_IMM, /* constant integer value */
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/* PTR_TO_PACKET represents:
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* skb->data
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* skb->data + imm
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* skb->data + (u16) var
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* skb->data + (u16) var + imm
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* if (range > 0) then [ptr, ptr + range - off) is safe to access
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* if (id > 0) means that some 'var' was added
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* if (off > 0) menas that 'imm' was added
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*/
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PTR_TO_PACKET,
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PTR_TO_PACKET_END, /* skb->data + headlen */
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};
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struct bpf_prog;
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struct bpf_verifier_ops {
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/* return eBPF function prototype for verification */
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const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
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/* return true if 'size' wide access at offset 'off' within bpf_context
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* with 'type' (read or write) is allowed
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*/
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bool (*is_valid_access)(int off, int size, enum bpf_access_type type,
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enum bpf_reg_type *reg_type);
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int (*gen_prologue)(struct bpf_insn *insn, bool direct_write,
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const struct bpf_prog *prog);
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u32 (*convert_ctx_access)(enum bpf_access_type type, int dst_reg,
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int src_reg, int ctx_off,
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struct bpf_insn *insn, struct bpf_prog *prog);
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};
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struct bpf_prog_type_list {
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struct list_head list_node;
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const struct bpf_verifier_ops *ops;
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enum bpf_prog_type type;
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};
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struct bpf_prog_aux {
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atomic_t refcnt;
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u32 used_map_cnt;
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u32 max_ctx_offset;
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const struct bpf_verifier_ops *ops;
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struct bpf_map **used_maps;
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struct bpf_prog *prog;
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struct user_struct *user;
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union {
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struct work_struct work;
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struct rcu_head rcu;
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};
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};
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struct bpf_array {
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struct bpf_map map;
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u32 elem_size;
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/* 'ownership' of prog_array is claimed by the first program that
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* is going to use this map or by the first program which FD is stored
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* in the map to make sure that all callers and callees have the same
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* prog_type and JITed flag
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*/
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enum bpf_prog_type owner_prog_type;
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bool owner_jited;
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union {
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char value[0] __aligned(8);
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void *ptrs[0] __aligned(8);
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void __percpu *pptrs[0] __aligned(8);
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};
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};
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#define MAX_TAIL_CALL_CNT 32
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struct bpf_event_entry {
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struct perf_event *event;
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struct file *perf_file;
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struct file *map_file;
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struct rcu_head rcu;
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};
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u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
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u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
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bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
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const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
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typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
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unsigned long off, unsigned long len);
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u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
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void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);
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#ifdef CONFIG_BPF_SYSCALL
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DECLARE_PER_CPU(int, bpf_prog_active);
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void bpf_register_prog_type(struct bpf_prog_type_list *tl);
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void bpf_register_map_type(struct bpf_map_type_list *tl);
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struct bpf_prog *bpf_prog_get(u32 ufd);
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struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type);
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struct bpf_prog *bpf_prog_add(struct bpf_prog *prog, int i);
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struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog);
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void bpf_prog_put(struct bpf_prog *prog);
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struct bpf_map *bpf_map_get_with_uref(u32 ufd);
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struct bpf_map *__bpf_map_get(struct fd f);
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struct bpf_map *bpf_map_inc(struct bpf_map *map, bool uref);
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void bpf_map_put_with_uref(struct bpf_map *map);
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void bpf_map_put(struct bpf_map *map);
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int bpf_map_precharge_memlock(u32 pages);
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extern int sysctl_unprivileged_bpf_disabled;
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int bpf_map_new_fd(struct bpf_map *map);
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int bpf_prog_new_fd(struct bpf_prog *prog);
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int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
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int bpf_obj_get_user(const char __user *pathname);
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int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
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int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
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int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
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u64 flags);
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int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
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u64 flags);
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int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value);
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int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
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void *key, void *value, u64 map_flags);
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void bpf_fd_array_map_clear(struct bpf_map *map);
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/* memcpy that is used with 8-byte aligned pointers, power-of-8 size and
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* forced to use 'long' read/writes to try to atomically copy long counters.
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* Best-effort only. No barriers here, since it _will_ race with concurrent
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* updates from BPF programs. Called from bpf syscall and mostly used with
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* size 8 or 16 bytes, so ask compiler to inline it.
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*/
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static inline void bpf_long_memcpy(void *dst, const void *src, u32 size)
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{
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const long *lsrc = src;
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long *ldst = dst;
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size /= sizeof(long);
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while (size--)
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*ldst++ = *lsrc++;
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}
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/* verify correctness of eBPF program */
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int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);
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#else
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static inline void bpf_register_prog_type(struct bpf_prog_type_list *tl)
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{
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}
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static inline struct bpf_prog *bpf_prog_get(u32 ufd)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
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enum bpf_prog_type type)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline struct bpf_prog *bpf_prog_add(struct bpf_prog *prog, int i)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline void bpf_prog_put(struct bpf_prog *prog)
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{
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}
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static inline struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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#endif /* CONFIG_BPF_SYSCALL */
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/* verifier prototypes for helper functions called from eBPF programs */
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extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
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extern const struct bpf_func_proto bpf_map_update_elem_proto;
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extern const struct bpf_func_proto bpf_map_delete_elem_proto;
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extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
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extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
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extern const struct bpf_func_proto bpf_tail_call_proto;
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extern const struct bpf_func_proto bpf_ktime_get_ns_proto;
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extern const struct bpf_func_proto bpf_get_current_pid_tgid_proto;
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extern const struct bpf_func_proto bpf_get_current_uid_gid_proto;
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extern const struct bpf_func_proto bpf_get_current_comm_proto;
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extern const struct bpf_func_proto bpf_skb_vlan_push_proto;
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extern const struct bpf_func_proto bpf_skb_vlan_pop_proto;
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extern const struct bpf_func_proto bpf_get_stackid_proto;
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/* Shared helpers among cBPF and eBPF. */
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void bpf_user_rnd_init_once(void);
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u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
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#endif /* _LINUX_BPF_H */
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