UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity
OpenCloudOS-Kernel/include/linux/bpf.h

187 lines
5.5 KiB
C
Raw Normal View History

bpf: introduce BPF syscall and maps BPF syscall is a multiplexor for a range of different operations on eBPF. This patch introduces syscall with single command to create a map. Next patch adds commands to access maps. 'maps' is a generic storage of different types for sharing data between kernel and userspace. Userspace example: /* this syscall wrapper creates a map with given type and attributes * and returns map_fd on success. * use close(map_fd) to delete the map */ int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size, int max_entries) { union bpf_attr attr = { .map_type = map_type, .key_size = key_size, .value_size = value_size, .max_entries = max_entries }; return bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); } 'union bpf_attr' is backwards compatible with future extensions. More details in Documentation/networking/filter.txt and in manpage Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:57 +08:00
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#ifndef _LINUX_BPF_H
#define _LINUX_BPF_H 1
#include <uapi/linux/bpf.h>
#include <linux/workqueue.h>
bpf: add lookup/update/delete/iterate methods to BPF maps 'maps' is a generic storage of different types for sharing data between kernel and userspace. The maps are accessed from user space via BPF syscall, which has commands: - create a map with given type and attributes fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size) returns fd or negative error - lookup key in a given map referenced by fd err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero and stores found elem into value or negative error - create or update key/value pair in a given map err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero or negative error - find and delete element by key in a given map err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key - iterate map elements (based on input key return next_key) err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->next_key - close(fd) deletes the map Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:59 +08:00
#include <linux/file.h>
bpf: introduce BPF syscall and maps BPF syscall is a multiplexor for a range of different operations on eBPF. This patch introduces syscall with single command to create a map. Next patch adds commands to access maps. 'maps' is a generic storage of different types for sharing data between kernel and userspace. Userspace example: /* this syscall wrapper creates a map with given type and attributes * and returns map_fd on success. * use close(map_fd) to delete the map */ int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size, int max_entries) { union bpf_attr attr = { .map_type = map_type, .key_size = key_size, .value_size = value_size, .max_entries = max_entries }; return bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); } 'union bpf_attr' is backwards compatible with future extensions. More details in Documentation/networking/filter.txt and in manpage Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:57 +08:00
struct bpf_map;
/* map is generic key/value storage optionally accesible by eBPF programs */
struct bpf_map_ops {
/* funcs callable from userspace (via syscall) */
struct bpf_map *(*map_alloc)(union bpf_attr *attr);
void (*map_free)(struct bpf_map *);
bpf: add lookup/update/delete/iterate methods to BPF maps 'maps' is a generic storage of different types for sharing data between kernel and userspace. The maps are accessed from user space via BPF syscall, which has commands: - create a map with given type and attributes fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size) returns fd or negative error - lookup key in a given map referenced by fd err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero and stores found elem into value or negative error - create or update key/value pair in a given map err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero or negative error - find and delete element by key in a given map err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key - iterate map elements (based on input key return next_key) err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->next_key - close(fd) deletes the map Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:59 +08:00
int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
/* funcs callable from userspace and from eBPF programs */
void *(*map_lookup_elem)(struct bpf_map *map, void *key);
bpf: add 'flags' attribute to BPF_MAP_UPDATE_ELEM command the current meaning of BPF_MAP_UPDATE_ELEM syscall command is: either update existing map element or create a new one. Initially the plan was to add a new command to handle the case of 'create new element if it didn't exist', but 'flags' style looks cleaner and overall diff is much smaller (more code reused), so add 'flags' attribute to BPF_MAP_UPDATE_ELEM command with the following meaning: #define BPF_ANY 0 /* create new element or update existing */ #define BPF_NOEXIST 1 /* create new element if it didn't exist */ #define BPF_EXIST 2 /* update existing element */ bpf_update_elem(fd, key, value, BPF_NOEXIST) call can fail with EEXIST if element already exists. bpf_update_elem(fd, key, value, BPF_EXIST) can fail with ENOENT if element doesn't exist. Userspace will call it as: int bpf_update_elem(int fd, void *key, void *value, __u64 flags) { union bpf_attr attr = { .map_fd = fd, .key = ptr_to_u64(key), .value = ptr_to_u64(value), .flags = flags; }; return bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr)); } First two bits of 'flags' are used to encode style of bpf_update_elem() command. Bits 2-63 are reserved for future use. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-11-14 09:36:44 +08:00
int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
bpf: add lookup/update/delete/iterate methods to BPF maps 'maps' is a generic storage of different types for sharing data between kernel and userspace. The maps are accessed from user space via BPF syscall, which has commands: - create a map with given type and attributes fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size) returns fd or negative error - lookup key in a given map referenced by fd err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero and stores found elem into value or negative error - create or update key/value pair in a given map err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero or negative error - find and delete element by key in a given map err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key - iterate map elements (based on input key return next_key) err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->next_key - close(fd) deletes the map Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:59 +08:00
int (*map_delete_elem)(struct bpf_map *map, void *key);
bpf: introduce BPF syscall and maps BPF syscall is a multiplexor for a range of different operations on eBPF. This patch introduces syscall with single command to create a map. Next patch adds commands to access maps. 'maps' is a generic storage of different types for sharing data between kernel and userspace. Userspace example: /* this syscall wrapper creates a map with given type and attributes * and returns map_fd on success. * use close(map_fd) to delete the map */ int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size, int max_entries) { union bpf_attr attr = { .map_type = map_type, .key_size = key_size, .value_size = value_size, .max_entries = max_entries }; return bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); } 'union bpf_attr' is backwards compatible with future extensions. More details in Documentation/networking/filter.txt and in manpage Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:57 +08:00
};
struct bpf_map {
atomic_t refcnt;
enum bpf_map_type map_type;
u32 key_size;
u32 value_size;
u32 max_entries;
ebpf: constify various function pointer structs We can move bpf_map_ops and bpf_verifier_ops and other structs into ro section, bpf_map_type_list and bpf_prog_type_list into read mostly. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:42 +08:00
const struct bpf_map_ops *ops;
bpf: introduce BPF syscall and maps BPF syscall is a multiplexor for a range of different operations on eBPF. This patch introduces syscall with single command to create a map. Next patch adds commands to access maps. 'maps' is a generic storage of different types for sharing data between kernel and userspace. Userspace example: /* this syscall wrapper creates a map with given type and attributes * and returns map_fd on success. * use close(map_fd) to delete the map */ int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size, int max_entries) { union bpf_attr attr = { .map_type = map_type, .key_size = key_size, .value_size = value_size, .max_entries = max_entries }; return bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); } 'union bpf_attr' is backwards compatible with future extensions. More details in Documentation/networking/filter.txt and in manpage Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:57 +08:00
struct work_struct work;
};
struct bpf_map_type_list {
struct list_head list_node;
ebpf: constify various function pointer structs We can move bpf_map_ops and bpf_verifier_ops and other structs into ro section, bpf_map_type_list and bpf_prog_type_list into read mostly. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:42 +08:00
const struct bpf_map_ops *ops;
bpf: introduce BPF syscall and maps BPF syscall is a multiplexor for a range of different operations on eBPF. This patch introduces syscall with single command to create a map. Next patch adds commands to access maps. 'maps' is a generic storage of different types for sharing data between kernel and userspace. Userspace example: /* this syscall wrapper creates a map with given type and attributes * and returns map_fd on success. * use close(map_fd) to delete the map */ int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size, int max_entries) { union bpf_attr attr = { .map_type = map_type, .key_size = key_size, .value_size = value_size, .max_entries = max_entries }; return bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); } 'union bpf_attr' is backwards compatible with future extensions. More details in Documentation/networking/filter.txt and in manpage Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:57 +08:00
enum bpf_map_type type;
};
bpf: verifier (add verifier core) This patch adds verifier core which simulates execution of every insn and records the state of registers and program stack. Every branch instruction seen during simulation is pushed into state stack. When verifier reaches BPF_EXIT, it pops the state from the stack and continues until it reaches BPF_EXIT again. For program: 1: bpf_mov r1, xxx 2: if (r1 == 0) goto 5 3: bpf_mov r0, 1 4: goto 6 5: bpf_mov r0, 2 6: bpf_exit The verifier will walk insns: 1, 2, 3, 4, 6 then it will pop the state recorded at insn#2 and will continue: 5, 6 This way it walks all possible paths through the program and checks all possible values of registers. While doing so, it checks for: - invalid instructions - uninitialized register access - uninitialized stack access - misaligned stack access - out of range stack access - invalid calling convention - instruction encoding is not using reserved fields Kernel subsystem configures the verifier with two callbacks: - bool (*is_valid_access)(int off, int size, enum bpf_access_type type); that provides information to the verifer which fields of 'ctx' are accessible (remember 'ctx' is the first argument to eBPF program) - const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id); returns argument constraints of kernel helper functions that eBPF program may call, so that verifier can checks that R1-R5 types match the prototype More details in Documentation/networking/filter.txt and in kernel/bpf/verifier.c Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:06 +08:00
/* function argument constraints */
enum bpf_arg_type {
ebpf: verifier: check that call reg with ARG_ANYTHING is initialized I noticed that a helper function with argument type ARG_ANYTHING does not need to have an initialized value (register). This can worst case lead to unintented stack memory leakage in future helper functions if they are not carefully designed, or unintended application behaviour in case the application developer was not careful enough to match a correct helper function signature in the API. The underlying issue is that ARG_ANYTHING should actually be split into two different semantics: 1) ARG_DONTCARE for function arguments that the helper function does not care about (in other words: the default for unused function arguments), and 2) ARG_ANYTHING that is an argument actually being used by a helper function and *guaranteed* to be an initialized register. The current risk is low: ARG_ANYTHING is only used for the 'flags' argument (r4) in bpf_map_update_elem() that internally does strict checking. Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-13 00:21:42 +08:00
ARG_DONTCARE = 0, /* unused argument in helper function */
bpf: verifier (add verifier core) This patch adds verifier core which simulates execution of every insn and records the state of registers and program stack. Every branch instruction seen during simulation is pushed into state stack. When verifier reaches BPF_EXIT, it pops the state from the stack and continues until it reaches BPF_EXIT again. For program: 1: bpf_mov r1, xxx 2: if (r1 == 0) goto 5 3: bpf_mov r0, 1 4: goto 6 5: bpf_mov r0, 2 6: bpf_exit The verifier will walk insns: 1, 2, 3, 4, 6 then it will pop the state recorded at insn#2 and will continue: 5, 6 This way it walks all possible paths through the program and checks all possible values of registers. While doing so, it checks for: - invalid instructions - uninitialized register access - uninitialized stack access - misaligned stack access - out of range stack access - invalid calling convention - instruction encoding is not using reserved fields Kernel subsystem configures the verifier with two callbacks: - bool (*is_valid_access)(int off, int size, enum bpf_access_type type); that provides information to the verifer which fields of 'ctx' are accessible (remember 'ctx' is the first argument to eBPF program) - const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id); returns argument constraints of kernel helper functions that eBPF program may call, so that verifier can checks that R1-R5 types match the prototype More details in Documentation/networking/filter.txt and in kernel/bpf/verifier.c Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:06 +08:00
/* the following constraints used to prototype
* bpf_map_lookup/update/delete_elem() functions
*/
ARG_CONST_MAP_PTR, /* const argument used as pointer to bpf_map */
ARG_PTR_TO_MAP_KEY, /* pointer to stack used as map key */
ARG_PTR_TO_MAP_VALUE, /* pointer to stack used as map value */
/* the following constraints used to prototype bpf_memcmp() and other
* functions that access data on eBPF program stack
*/
ARG_PTR_TO_STACK, /* any pointer to eBPF program stack */
ARG_CONST_STACK_SIZE, /* number of bytes accessed from stack */
ebpf: verifier: check that call reg with ARG_ANYTHING is initialized I noticed that a helper function with argument type ARG_ANYTHING does not need to have an initialized value (register). This can worst case lead to unintented stack memory leakage in future helper functions if they are not carefully designed, or unintended application behaviour in case the application developer was not careful enough to match a correct helper function signature in the API. The underlying issue is that ARG_ANYTHING should actually be split into two different semantics: 1) ARG_DONTCARE for function arguments that the helper function does not care about (in other words: the default for unused function arguments), and 2) ARG_ANYTHING that is an argument actually being used by a helper function and *guaranteed* to be an initialized register. The current risk is low: ARG_ANYTHING is only used for the 'flags' argument (r4) in bpf_map_update_elem() that internally does strict checking. Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-13 00:21:42 +08:00
tc: bpf: generalize pedit action existing TC action 'pedit' can munge any bits of the packet. Generalize it for use in bpf programs attached as cls_bpf and act_bpf via bpf_skb_store_bytes() helper function. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Reviewed-by: Jiri Pirko <jiri@resnulli.us> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-27 10:53:57 +08:00
ARG_PTR_TO_CTX, /* pointer to context */
ebpf: verifier: check that call reg with ARG_ANYTHING is initialized I noticed that a helper function with argument type ARG_ANYTHING does not need to have an initialized value (register). This can worst case lead to unintented stack memory leakage in future helper functions if they are not carefully designed, or unintended application behaviour in case the application developer was not careful enough to match a correct helper function signature in the API. The underlying issue is that ARG_ANYTHING should actually be split into two different semantics: 1) ARG_DONTCARE for function arguments that the helper function does not care about (in other words: the default for unused function arguments), and 2) ARG_ANYTHING that is an argument actually being used by a helper function and *guaranteed* to be an initialized register. The current risk is low: ARG_ANYTHING is only used for the 'flags' argument (r4) in bpf_map_update_elem() that internally does strict checking. Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-13 00:21:42 +08:00
ARG_ANYTHING, /* any (initialized) argument is ok */
bpf: verifier (add verifier core) This patch adds verifier core which simulates execution of every insn and records the state of registers and program stack. Every branch instruction seen during simulation is pushed into state stack. When verifier reaches BPF_EXIT, it pops the state from the stack and continues until it reaches BPF_EXIT again. For program: 1: bpf_mov r1, xxx 2: if (r1 == 0) goto 5 3: bpf_mov r0, 1 4: goto 6 5: bpf_mov r0, 2 6: bpf_exit The verifier will walk insns: 1, 2, 3, 4, 6 then it will pop the state recorded at insn#2 and will continue: 5, 6 This way it walks all possible paths through the program and checks all possible values of registers. While doing so, it checks for: - invalid instructions - uninitialized register access - uninitialized stack access - misaligned stack access - out of range stack access - invalid calling convention - instruction encoding is not using reserved fields Kernel subsystem configures the verifier with two callbacks: - bool (*is_valid_access)(int off, int size, enum bpf_access_type type); that provides information to the verifer which fields of 'ctx' are accessible (remember 'ctx' is the first argument to eBPF program) - const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id); returns argument constraints of kernel helper functions that eBPF program may call, so that verifier can checks that R1-R5 types match the prototype More details in Documentation/networking/filter.txt and in kernel/bpf/verifier.c Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:06 +08:00
};
/* type of values returned from helper functions */
enum bpf_return_type {
RET_INTEGER, /* function returns integer */
RET_VOID, /* function doesn't return anything */
RET_PTR_TO_MAP_VALUE_OR_NULL, /* returns a pointer to map elem value or NULL */
};
bpf: expand BPF syscall with program load/unload eBPF programs are similar to kernel modules. They are loaded by the user process and automatically unloaded when process exits. Each eBPF program is a safe run-to-completion set of instructions. eBPF verifier statically determines that the program terminates and is safe to execute. The following syscall wrapper can be used to load the program: int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int insn_cnt, const char *license) { union bpf_attr attr = { .prog_type = prog_type, .insns = ptr_to_u64(insns), .insn_cnt = insn_cnt, .license = ptr_to_u64(license), }; return bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); } where 'insns' is an array of eBPF instructions and 'license' is a string that must be GPL compatible to call helper functions marked gpl_only Upon succesful load the syscall returns prog_fd. Use close(prog_fd) to unload the program. User space tests and examples follow in the later patches Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:00 +08:00
/* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
* to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
* instructions after verifying
*/
struct bpf_func_proto {
u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
bool gpl_only;
bpf: verifier (add verifier core) This patch adds verifier core which simulates execution of every insn and records the state of registers and program stack. Every branch instruction seen during simulation is pushed into state stack. When verifier reaches BPF_EXIT, it pops the state from the stack and continues until it reaches BPF_EXIT again. For program: 1: bpf_mov r1, xxx 2: if (r1 == 0) goto 5 3: bpf_mov r0, 1 4: goto 6 5: bpf_mov r0, 2 6: bpf_exit The verifier will walk insns: 1, 2, 3, 4, 6 then it will pop the state recorded at insn#2 and will continue: 5, 6 This way it walks all possible paths through the program and checks all possible values of registers. While doing so, it checks for: - invalid instructions - uninitialized register access - uninitialized stack access - misaligned stack access - out of range stack access - invalid calling convention - instruction encoding is not using reserved fields Kernel subsystem configures the verifier with two callbacks: - bool (*is_valid_access)(int off, int size, enum bpf_access_type type); that provides information to the verifer which fields of 'ctx' are accessible (remember 'ctx' is the first argument to eBPF program) - const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id); returns argument constraints of kernel helper functions that eBPF program may call, so that verifier can checks that R1-R5 types match the prototype More details in Documentation/networking/filter.txt and in kernel/bpf/verifier.c Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:06 +08:00
enum bpf_return_type ret_type;
enum bpf_arg_type arg1_type;
enum bpf_arg_type arg2_type;
enum bpf_arg_type arg3_type;
enum bpf_arg_type arg4_type;
enum bpf_arg_type arg5_type;
};
/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
* the first argument to eBPF programs.
* For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
*/
struct bpf_context;
enum bpf_access_type {
BPF_READ = 1,
BPF_WRITE = 2
bpf: expand BPF syscall with program load/unload eBPF programs are similar to kernel modules. They are loaded by the user process and automatically unloaded when process exits. Each eBPF program is a safe run-to-completion set of instructions. eBPF verifier statically determines that the program terminates and is safe to execute. The following syscall wrapper can be used to load the program: int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int insn_cnt, const char *license) { union bpf_attr attr = { .prog_type = prog_type, .insns = ptr_to_u64(insns), .insn_cnt = insn_cnt, .license = ptr_to_u64(license), }; return bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); } where 'insns' is an array of eBPF instructions and 'license' is a string that must be GPL compatible to call helper functions marked gpl_only Upon succesful load the syscall returns prog_fd. Use close(prog_fd) to unload the program. User space tests and examples follow in the later patches Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:00 +08:00
};
struct bpf_verifier_ops {
/* return eBPF function prototype for verification */
const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
bpf: verifier (add verifier core) This patch adds verifier core which simulates execution of every insn and records the state of registers and program stack. Every branch instruction seen during simulation is pushed into state stack. When verifier reaches BPF_EXIT, it pops the state from the stack and continues until it reaches BPF_EXIT again. For program: 1: bpf_mov r1, xxx 2: if (r1 == 0) goto 5 3: bpf_mov r0, 1 4: goto 6 5: bpf_mov r0, 2 6: bpf_exit The verifier will walk insns: 1, 2, 3, 4, 6 then it will pop the state recorded at insn#2 and will continue: 5, 6 This way it walks all possible paths through the program and checks all possible values of registers. While doing so, it checks for: - invalid instructions - uninitialized register access - uninitialized stack access - misaligned stack access - out of range stack access - invalid calling convention - instruction encoding is not using reserved fields Kernel subsystem configures the verifier with two callbacks: - bool (*is_valid_access)(int off, int size, enum bpf_access_type type); that provides information to the verifer which fields of 'ctx' are accessible (remember 'ctx' is the first argument to eBPF program) - const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id); returns argument constraints of kernel helper functions that eBPF program may call, so that verifier can checks that R1-R5 types match the prototype More details in Documentation/networking/filter.txt and in kernel/bpf/verifier.c Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:06 +08:00
/* return true if 'size' wide access at offset 'off' within bpf_context
* with 'type' (read or write) is allowed
*/
bool (*is_valid_access)(int off, int size, enum bpf_access_type type);
bpf: allow extended BPF programs access skb fields introduce user accessible mirror of in-kernel 'struct sk_buff': struct __sk_buff { __u32 len; __u32 pkt_type; __u32 mark; __u32 queue_mapping; }; bpf programs can do: int bpf_prog(struct __sk_buff *skb) { __u32 var = skb->pkt_type; which will be compiled to bpf assembler as: dst_reg = *(u32 *)(src_reg + 4) // 4 == offsetof(struct __sk_buff, pkt_type) bpf verifier will check validity of access and will convert it to: dst_reg = *(u8 *)(src_reg + offsetof(struct sk_buff, __pkt_type_offset)) dst_reg &= 7 since skb->pkt_type is a bitfield. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 02:57:42 +08:00
u32 (*convert_ctx_access)(int dst_reg, int src_reg, int ctx_off,
struct bpf_insn *insn);
bpf: expand BPF syscall with program load/unload eBPF programs are similar to kernel modules. They are loaded by the user process and automatically unloaded when process exits. Each eBPF program is a safe run-to-completion set of instructions. eBPF verifier statically determines that the program terminates and is safe to execute. The following syscall wrapper can be used to load the program: int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int insn_cnt, const char *license) { union bpf_attr attr = { .prog_type = prog_type, .insns = ptr_to_u64(insns), .insn_cnt = insn_cnt, .license = ptr_to_u64(license), }; return bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); } where 'insns' is an array of eBPF instructions and 'license' is a string that must be GPL compatible to call helper functions marked gpl_only Upon succesful load the syscall returns prog_fd. Use close(prog_fd) to unload the program. User space tests and examples follow in the later patches Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:00 +08:00
};
struct bpf_prog_type_list {
struct list_head list_node;
ebpf: constify various function pointer structs We can move bpf_map_ops and bpf_verifier_ops and other structs into ro section, bpf_map_type_list and bpf_prog_type_list into read mostly. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:42 +08:00
const struct bpf_verifier_ops *ops;
bpf: expand BPF syscall with program load/unload eBPF programs are similar to kernel modules. They are loaded by the user process and automatically unloaded when process exits. Each eBPF program is a safe run-to-completion set of instructions. eBPF verifier statically determines that the program terminates and is safe to execute. The following syscall wrapper can be used to load the program: int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int insn_cnt, const char *license) { union bpf_attr attr = { .prog_type = prog_type, .insns = ptr_to_u64(insns), .insn_cnt = insn_cnt, .license = ptr_to_u64(license), }; return bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); } where 'insns' is an array of eBPF instructions and 'license' is a string that must be GPL compatible to call helper functions marked gpl_only Upon succesful load the syscall returns prog_fd. Use close(prog_fd) to unload the program. User space tests and examples follow in the later patches Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:00 +08:00
enum bpf_prog_type type;
};
struct bpf_prog;
struct bpf_prog_aux {
atomic_t refcnt;
ebpf: move read-only fields to bpf_prog and shrink bpf_prog_aux is_gpl_compatible and prog_type should be moved directly into bpf_prog as they stay immutable during bpf_prog's lifetime, are core attributes and they can be locked as read-only later on via bpf_prog_select_runtime(). With a bit of rearranging, this also allows us to shrink bpf_prog_aux to exactly 1 cacheline. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:47 +08:00
u32 used_map_cnt;
ebpf: constify various function pointer structs We can move bpf_map_ops and bpf_verifier_ops and other structs into ro section, bpf_map_type_list and bpf_prog_type_list into read mostly. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:42 +08:00
const struct bpf_verifier_ops *ops;
bpf: expand BPF syscall with program load/unload eBPF programs are similar to kernel modules. They are loaded by the user process and automatically unloaded when process exits. Each eBPF program is a safe run-to-completion set of instructions. eBPF verifier statically determines that the program terminates and is safe to execute. The following syscall wrapper can be used to load the program: int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int insn_cnt, const char *license) { union bpf_attr attr = { .prog_type = prog_type, .insns = ptr_to_u64(insns), .insn_cnt = insn_cnt, .license = ptr_to_u64(license), }; return bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); } where 'insns' is an array of eBPF instructions and 'license' is a string that must be GPL compatible to call helper functions marked gpl_only Upon succesful load the syscall returns prog_fd. Use close(prog_fd) to unload the program. User space tests and examples follow in the later patches Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:00 +08:00
struct bpf_map **used_maps;
struct bpf_prog *prog;
struct work_struct work;
};
bpf: allow bpf programs to tail-call other bpf programs 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 <daniel@iogearbox.net> ========== - 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 <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-20 07:59:03 +08:00
struct bpf_array {
struct bpf_map map;
u32 elem_size;
/* 'ownership' of prog_array is claimed by the first program that
* is going to use this map or by the first program which FD is stored
* in the map to make sure that all callers and callees have the same
* prog_type and JITed flag
*/
enum bpf_prog_type owner_prog_type;
bool owner_jited;
union {
char value[0] __aligned(8);
struct bpf_prog *prog[0] __aligned(8);
};
};
#define MAX_TAIL_CALL_CNT 32
u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
void bpf_prog_array_map_clear(struct bpf_map *map);
bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
net: sock: allow eBPF programs to be attached to sockets introduce new setsockopt() command: setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd, sizeof(prog_fd)) where prog_fd was received from syscall bpf(BPF_PROG_LOAD, attr, ...) and attr->prog_type == BPF_PROG_TYPE_SOCKET_FILTER setsockopt() calls bpf_prog_get() which increments refcnt of the program, so it doesn't get unloaded while socket is using the program. The same eBPF program can be attached to multiple sockets. User task exit automatically closes socket which calls sk_filter_uncharge() which decrements refcnt of eBPF program Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-02 07:06:35 +08:00
#ifdef CONFIG_BPF_SYSCALL
ebpf: make internal bpf API independent of CONFIG_BPF_SYSCALL ifdefs Socket filter code and other subsystems with upcoming eBPF support should not need to deal with the fact that we have CONFIG_BPF_SYSCALL defined or not. Having the bpf syscall as a config option is a nice thing and I'd expect it to stay that way for expert users (I presume one day the default setting of it might change, though), but code making use of it should not care if it's actually enabled or not. Instead, hide this via header files and let the rest deal with it. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:44 +08:00
void bpf_register_prog_type(struct bpf_prog_type_list *tl);
ebpf: move CONFIG_BPF_SYSCALL-only function declarations Masami noted that it would be better to hide the remaining CONFIG_BPF_SYSCALL-only function declarations within the BPF header ifdef, w/o else path dummy alternatives since these functions are not supposed to have a user outside of CONFIG_BPF_SYSCALL. Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Reference: http://article.gmane.org/gmane.linux.kernel.api/8658 Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-02 22:21:55 +08:00
void bpf_register_map_type(struct bpf_map_type_list *tl);
ebpf: make internal bpf API independent of CONFIG_BPF_SYSCALL ifdefs Socket filter code and other subsystems with upcoming eBPF support should not need to deal with the fact that we have CONFIG_BPF_SYSCALL defined or not. Having the bpf syscall as a config option is a nice thing and I'd expect it to stay that way for expert users (I presume one day the default setting of it might change, though), but code making use of it should not care if it's actually enabled or not. Instead, hide this via header files and let the rest deal with it. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:44 +08:00
struct bpf_prog *bpf_prog_get(u32 ufd);
ebpf: move CONFIG_BPF_SYSCALL-only function declarations Masami noted that it would be better to hide the remaining CONFIG_BPF_SYSCALL-only function declarations within the BPF header ifdef, w/o else path dummy alternatives since these functions are not supposed to have a user outside of CONFIG_BPF_SYSCALL. Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Reference: http://article.gmane.org/gmane.linux.kernel.api/8658 Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-02 22:21:55 +08:00
void bpf_prog_put(struct bpf_prog *prog);
struct bpf_map *bpf_map_get(struct fd f);
void bpf_map_put(struct bpf_map *map);
/* verify correctness of eBPF program */
bpf: allow extended BPF programs access skb fields introduce user accessible mirror of in-kernel 'struct sk_buff': struct __sk_buff { __u32 len; __u32 pkt_type; __u32 mark; __u32 queue_mapping; }; bpf programs can do: int bpf_prog(struct __sk_buff *skb) { __u32 var = skb->pkt_type; which will be compiled to bpf assembler as: dst_reg = *(u32 *)(src_reg + 4) // 4 == offsetof(struct __sk_buff, pkt_type) bpf verifier will check validity of access and will convert it to: dst_reg = *(u8 *)(src_reg + offsetof(struct sk_buff, __pkt_type_offset)) dst_reg &= 7 since skb->pkt_type is a bitfield. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 02:57:42 +08:00
int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);
net: sock: allow eBPF programs to be attached to sockets introduce new setsockopt() command: setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd, sizeof(prog_fd)) where prog_fd was received from syscall bpf(BPF_PROG_LOAD, attr, ...) and attr->prog_type == BPF_PROG_TYPE_SOCKET_FILTER setsockopt() calls bpf_prog_get() which increments refcnt of the program, so it doesn't get unloaded while socket is using the program. The same eBPF program can be attached to multiple sockets. User task exit automatically closes socket which calls sk_filter_uncharge() which decrements refcnt of eBPF program Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-02 07:06:35 +08:00
#else
ebpf: make internal bpf API independent of CONFIG_BPF_SYSCALL ifdefs Socket filter code and other subsystems with upcoming eBPF support should not need to deal with the fact that we have CONFIG_BPF_SYSCALL defined or not. Having the bpf syscall as a config option is a nice thing and I'd expect it to stay that way for expert users (I presume one day the default setting of it might change, though), but code making use of it should not care if it's actually enabled or not. Instead, hide this via header files and let the rest deal with it. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:44 +08:00
static inline void bpf_register_prog_type(struct bpf_prog_type_list *tl)
{
}
static inline struct bpf_prog *bpf_prog_get(u32 ufd)
{
return ERR_PTR(-EOPNOTSUPP);
}
static inline void bpf_prog_put(struct bpf_prog *prog)
{
}
ebpf: move CONFIG_BPF_SYSCALL-only function declarations Masami noted that it would be better to hide the remaining CONFIG_BPF_SYSCALL-only function declarations within the BPF header ifdef, w/o else path dummy alternatives since these functions are not supposed to have a user outside of CONFIG_BPF_SYSCALL. Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Reference: http://article.gmane.org/gmane.linux.kernel.api/8658 Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-02 22:21:55 +08:00
#endif /* CONFIG_BPF_SYSCALL */
bpf: expand BPF syscall with program load/unload eBPF programs are similar to kernel modules. They are loaded by the user process and automatically unloaded when process exits. Each eBPF program is a safe run-to-completion set of instructions. eBPF verifier statically determines that the program terminates and is safe to execute. The following syscall wrapper can be used to load the program: int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int insn_cnt, const char *license) { union bpf_attr attr = { .prog_type = prog_type, .insns = ptr_to_u64(insns), .insn_cnt = insn_cnt, .license = ptr_to_u64(license), }; return bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); } where 'insns' is an array of eBPF instructions and 'license' is a string that must be GPL compatible to call helper functions marked gpl_only Upon succesful load the syscall returns prog_fd. Use close(prog_fd) to unload the program. User space tests and examples follow in the later patches Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:17:00 +08:00
bpf: allow eBPF programs to use maps expose bpf_map_lookup_elem(), bpf_map_update_elem(), bpf_map_delete_elem() map accessors to eBPF programs Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-11-14 09:36:49 +08:00
/* verifier prototypes for helper functions called from eBPF programs */
ebpf: constify various function pointer structs We can move bpf_map_ops and bpf_verifier_ops and other structs into ro section, bpf_map_type_list and bpf_prog_type_list into read mostly. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-01 19:31:42 +08:00
extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
extern const struct bpf_func_proto bpf_map_update_elem_proto;
extern const struct bpf_func_proto bpf_map_delete_elem_proto;
bpf: allow eBPF programs to use maps expose bpf_map_lookup_elem(), bpf_map_update_elem(), bpf_map_delete_elem() map accessors to eBPF programs Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-11-14 09:36:49 +08:00
ebpf: add prandom helper for packet sampling This work is similar to commit 4cd3675ebf74 ("filter: added BPF random opcode") and adds a possibility for packet sampling in eBPF. Currently, this is only possible in classic BPF and useful to combine sampling with f.e. packet sockets, possible also with tc. Example function proto-type looks like: u32 (*prandom_u32)(void) = (void *)BPF_FUNC_get_prandom_u32; Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 09:27:16 +08:00
extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
ebpf: add helper for obtaining current processor id This patch adds the possibility to obtain raw_smp_processor_id() in eBPF. Currently, this is only possible in classic BPF where commit da2033c28226 ("filter: add SKF_AD_RXHASH and SKF_AD_CPU") has added facilities for this. Perhaps most importantly, this would also allow us to track per CPU statistics with eBPF maps, or to implement a poor-man's per CPU data structure through eBPF maps. Example function proto-type looks like: u32 (*smp_processor_id)(void) = (void *)BPF_FUNC_get_smp_processor_id; Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 09:27:17 +08:00
extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
bpf: allow bpf programs to tail-call other bpf programs 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 <daniel@iogearbox.net> ========== - 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 <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-20 07:59:03 +08:00
extern const struct bpf_func_proto bpf_tail_call_proto;
ebpf: add prandom helper for packet sampling This work is similar to commit 4cd3675ebf74 ("filter: added BPF random opcode") and adds a possibility for packet sampling in eBPF. Currently, this is only possible in classic BPF and useful to combine sampling with f.e. packet sockets, possible also with tc. Example function proto-type looks like: u32 (*prandom_u32)(void) = (void *)BPF_FUNC_get_prandom_u32; Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 09:27:16 +08:00
bpf: introduce BPF syscall and maps BPF syscall is a multiplexor for a range of different operations on eBPF. This patch introduces syscall with single command to create a map. Next patch adds commands to access maps. 'maps' is a generic storage of different types for sharing data between kernel and userspace. Userspace example: /* this syscall wrapper creates a map with given type and attributes * and returns map_fd on success. * use close(map_fd) to delete the map */ int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size, int max_entries) { union bpf_attr attr = { .map_type = map_type, .key_size = key_size, .value_size = value_size, .max_entries = max_entries }; return bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); } 'union bpf_attr' is backwards compatible with future extensions. More details in Documentation/networking/filter.txt and in manpage Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 15:16:57 +08:00
#endif /* _LINUX_BPF_H */