From 99c55f7d47c0dc6fc64729f37bf435abf43f4c60 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:16:57 -0700 Subject: 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 Signed-off-by: David S. Miller --- include/linux/bpf.h | 41 +++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/bpf.h | 23 +++++++++++++++++++++++ 2 files changed, 64 insertions(+) create mode 100644 include/linux/bpf.h (limited to 'include') diff --git a/include/linux/bpf.h b/include/linux/bpf.h new file mode 100644 index 000000000000..48014a71f0fe --- /dev/null +++ b/include/linux/bpf.h @@ -0,0 +1,41 @@ +/* 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 +#include + +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 *); +}; + +struct bpf_map { + atomic_t refcnt; + enum bpf_map_type map_type; + u32 key_size; + u32 value_size; + u32 max_entries; + struct bpf_map_ops *ops; + struct work_struct work; +}; + +struct bpf_map_type_list { + struct list_head list_node; + struct bpf_map_ops *ops; + enum bpf_map_type type; +}; + +void bpf_register_map_type(struct bpf_map_type_list *tl); +void bpf_map_put(struct bpf_map *map); + +#endif /* _LINUX_BPF_H */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 479ed0b6be16..f58a10f9670c 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -62,4 +62,27 @@ struct bpf_insn { __s32 imm; /* signed immediate constant */ }; +/* BPF syscall commands */ +enum bpf_cmd { + /* create a map with given type and attributes + * fd = bpf(BPF_MAP_CREATE, union bpf_attr *, u32 size) + * returns fd or negative error + * map is deleted when fd is closed + */ + BPF_MAP_CREATE, +}; + +enum bpf_map_type { + BPF_MAP_TYPE_UNSPEC, +}; + +union bpf_attr { + struct { /* anonymous struct used by BPF_MAP_CREATE command */ + __u32 map_type; /* one of enum bpf_map_type */ + __u32 key_size; /* size of key in bytes */ + __u32 value_size; /* size of value in bytes */ + __u32 max_entries; /* max number of entries in a map */ + }; +} __attribute__((aligned(8))); + #endif /* _UAPI__LINUX_BPF_H__ */ -- cgit v1.2.3 From 749730ce42a2121e1c88350d69478bff3994b10a Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:16:58 -0700 Subject: bpf: enable bpf syscall on x64 and i386 done as separate commit to ease conflict resolution Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/syscalls.h | 3 ++- include/uapi/asm-generic/unistd.h | 4 +++- 2 files changed, 5 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 0f86d85a9ce4..bda9b81357cc 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -65,6 +65,7 @@ struct old_linux_dirent; struct perf_event_attr; struct file_handle; struct sigaltstack; +union bpf_attr; #include #include @@ -875,5 +876,5 @@ asmlinkage long sys_seccomp(unsigned int op, unsigned int flags, const char __user *uargs); asmlinkage long sys_getrandom(char __user *buf, size_t count, unsigned int flags); - +asmlinkage long sys_bpf(int cmd, union bpf_attr *attr, unsigned int size); #endif diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index 11d11bc5c78f..22749c134117 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -705,9 +705,11 @@ __SYSCALL(__NR_seccomp, sys_seccomp) __SYSCALL(__NR_getrandom, sys_getrandom) #define __NR_memfd_create 279 __SYSCALL(__NR_memfd_create, sys_memfd_create) +#define __NR_bpf 280 +__SYSCALL(__NR_bpf, sys_bpf) #undef __NR_syscalls -#define __NR_syscalls 280 +#define __NR_syscalls 281 /* * All syscalls below here should go away really, -- cgit v1.2.3 From db20fd2b01087bdfbe30bce314a198eefedcc42e Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:16:59 -0700 Subject: 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 Signed-off-by: David S. Miller --- include/linux/bpf.h | 8 ++++++++ include/uapi/linux/bpf.h | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+) (limited to 'include') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 48014a71f0fe..2887f3f9da59 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -9,6 +9,7 @@ #include #include +#include struct bpf_map; @@ -17,6 +18,12 @@ 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 *); + 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); + int (*map_update_elem)(struct bpf_map *map, void *key, void *value); + int (*map_delete_elem)(struct bpf_map *map, void *key); }; struct bpf_map { @@ -37,5 +44,6 @@ struct bpf_map_type_list { void bpf_register_map_type(struct bpf_map_type_list *tl); void bpf_map_put(struct bpf_map *map); +struct bpf_map *bpf_map_get(struct fd f); #endif /* _LINUX_BPF_H */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index f58a10f9670c..395cabd2ca0a 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -70,6 +70,35 @@ enum bpf_cmd { * map is deleted when fd is closed */ BPF_MAP_CREATE, + + /* lookup key in a given map + * 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 + */ + BPF_MAP_LOOKUP_ELEM, + + /* 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 + */ + BPF_MAP_UPDATE_ELEM, + + /* find and delete elem by key in a given map + * err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size) + * Using attr->map_fd, attr->key + * returns zero or negative error + */ + BPF_MAP_DELETE_ELEM, + + /* lookup key in a given map and 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 + * returns zero and stores next key or negative error + */ + BPF_MAP_GET_NEXT_KEY, }; enum bpf_map_type { @@ -83,6 +112,15 @@ union bpf_attr { __u32 value_size; /* size of value in bytes */ __u32 max_entries; /* max number of entries in a map */ }; + + struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ + __u32 map_fd; + __aligned_u64 key; + union { + __aligned_u64 value; + __aligned_u64 next_key; + }; + }; } __attribute__((aligned(8))); #endif /* _UAPI__LINUX_BPF_H__ */ -- cgit v1.2.3 From 09756af46893c18839062976c3252e93a1beeba7 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:17:00 -0700 Subject: 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 Signed-off-by: David S. Miller --- include/linux/bpf.h | 38 ++++++++++++++++++++++++++++++++++++++ include/linux/filter.h | 8 ++------ include/uapi/linux/bpf.h | 26 ++++++++++++++++++++++++++ 3 files changed, 66 insertions(+), 6 deletions(-) (limited to 'include') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2887f3f9da59..92979182be81 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -46,4 +46,42 @@ void bpf_register_map_type(struct bpf_map_type_list *tl); void bpf_map_put(struct bpf_map *map); struct bpf_map *bpf_map_get(struct fd f); +/* 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; +}; + +struct bpf_verifier_ops { + /* return eBPF function prototype for verification */ + const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id); +}; + +struct bpf_prog_type_list { + struct list_head list_node; + struct bpf_verifier_ops *ops; + enum bpf_prog_type type; +}; + +void bpf_register_prog_type(struct bpf_prog_type_list *tl); + +struct bpf_prog; + +struct bpf_prog_aux { + atomic_t refcnt; + bool is_gpl_compatible; + enum bpf_prog_type prog_type; + struct bpf_verifier_ops *ops; + struct bpf_map **used_maps; + u32 used_map_cnt; + struct bpf_prog *prog; + struct work_struct work; +}; + +void bpf_prog_put(struct bpf_prog *prog); +struct bpf_prog *bpf_prog_get(u32 ufd); + #endif /* _LINUX_BPF_H */ diff --git a/include/linux/filter.h b/include/linux/filter.h index 1a0bc6d134d7..4ffc0958d85e 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -21,6 +21,7 @@ struct sk_buff; struct sock; struct seccomp_data; +struct bpf_prog_aux; /* ArgX, context and stack frame pointer register positions. Note, * Arg1, Arg2, Arg3, etc are used as argument mappings of function @@ -300,17 +301,12 @@ struct bpf_binary_header { u8 image[]; }; -struct bpf_work_struct { - struct bpf_prog *prog; - struct work_struct work; -}; - struct bpf_prog { u16 pages; /* Number of allocated pages */ bool jited; /* Is our filter JIT'ed? */ u32 len; /* Number of filter blocks */ struct sock_fprog_kern *orig_prog; /* Original BPF program */ - struct bpf_work_struct *work; /* Deferred free work struct */ + struct bpf_prog_aux *aux; /* Auxiliary fields */ unsigned int (*bpf_func)(const struct sk_buff *skb, const struct bpf_insn *filter); /* Instructions for interpreter */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 395cabd2ca0a..424f442016e7 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -99,12 +99,23 @@ enum bpf_cmd { * returns zero and stores next key or negative error */ BPF_MAP_GET_NEXT_KEY, + + /* verify and load eBPF program + * prog_fd = bpf(BPF_PROG_LOAD, union bpf_attr *attr, u32 size) + * Using attr->prog_type, attr->insns, attr->license + * returns fd or negative error + */ + BPF_PROG_LOAD, }; enum bpf_map_type { BPF_MAP_TYPE_UNSPEC, }; +enum bpf_prog_type { + BPF_PROG_TYPE_UNSPEC, +}; + union bpf_attr { struct { /* anonymous struct used by BPF_MAP_CREATE command */ __u32 map_type; /* one of enum bpf_map_type */ @@ -121,6 +132,21 @@ union bpf_attr { __aligned_u64 next_key; }; }; + + struct { /* anonymous struct used by BPF_PROG_LOAD command */ + __u32 prog_type; /* one of enum bpf_prog_type */ + __u32 insn_cnt; + __aligned_u64 insns; + __aligned_u64 license; + }; } __attribute__((aligned(8))); +/* integer value in 'imm' field of BPF_CALL instruction selects which helper + * function eBPF program intends to call + */ +enum bpf_func_id { + BPF_FUNC_unspec, + __BPF_FUNC_MAX_ID, +}; + #endif /* _UAPI__LINUX_BPF_H__ */ -- cgit v1.2.3 From 51580e798cb61b0fc63fa3aa6c5c975375aa0550 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:17:02 -0700 Subject: bpf: verifier (add docs) this patch adds all of eBPF verfier documentation and empty bpf_check() The end goal for the verifier is to statically check safety of the program. Verifier will catch: - loops - out of range jumps - unreachable instructions - invalid instructions - uninitialized register access - uninitialized stack access - misaligned stack access - out of range stack access - invalid calling convention More details in Documentation/networking/filter.txt Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/bpf.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 92979182be81..9dfeb36f8971 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -83,5 +83,7 @@ struct bpf_prog_aux { void bpf_prog_put(struct bpf_prog *prog); struct bpf_prog *bpf_prog_get(u32 ufd); +/* verify correctness of eBPF program */ +int bpf_check(struct bpf_prog *fp, union bpf_attr *attr); #endif /* _LINUX_BPF_H */ -- cgit v1.2.3 From cbd357008604925355ae7b54a09137dabb81b580 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:17:03 -0700 Subject: bpf: verifier (add ability to receive verification log) add optional attributes for BPF_PROG_LOAD syscall: union bpf_attr { struct { ... __u32 log_level; /* verbosity level of eBPF verifier */ __u32 log_size; /* size of user buffer */ __aligned_u64 log_buf; /* user supplied 'char *buffer' */ }; }; when log_level > 0 the verifier will return its verification log in the user supplied buffer 'log_buf' which can be used by program author to analyze why verifier rejected given program. 'Understanding eBPF verifier messages' section of Documentation/networking/filter.txt provides several examples of these messages, like the program: BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), BPF_LD_MAP_FD(BPF_REG_1, 0), BPF_CALL_FUNC(BPF_FUNC_map_lookup_elem), BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1), BPF_ST_MEM(BPF_DW, BPF_REG_0, 4, 0), BPF_EXIT_INSN(), will be rejected with the following multi-line message in log_buf: 0: (7a) *(u64 *)(r10 -8) = 0 1: (bf) r2 = r10 2: (07) r2 += -8 3: (b7) r1 = 0 4: (85) call 1 5: (15) if r0 == 0x0 goto pc+1 R0=map_ptr R10=fp 6: (7a) *(u64 *)(r0 +4) = 0 misaligned access off 4 size 8 The format of the output can change at any time as verifier evolves. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/uapi/linux/bpf.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 424f442016e7..31b0ac208a52 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -138,6 +138,9 @@ union bpf_attr { __u32 insn_cnt; __aligned_u64 insns; __aligned_u64 license; + __u32 log_level; /* verbosity level of verifier */ + __u32 log_size; /* size of user buffer */ + __aligned_u64 log_buf; /* user supplied buffer */ }; } __attribute__((aligned(8))); -- cgit v1.2.3 From 0246e64d9a5fcd4805198de59b9b5cf1f974eb41 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:17:04 -0700 Subject: bpf: handle pseudo BPF_LD_IMM64 insn eBPF programs passed from userspace are using pseudo BPF_LD_IMM64 instructions to refer to process-local map_fd. Scan the program for such instructions and if FDs are valid, convert them to 'struct bpf_map' pointers which will be used by verifier to check access to maps in bpf_map_lookup/update() calls. If program passes verifier, convert pseudo BPF_LD_IMM64 into generic by dropping BPF_PSEUDO_MAP_FD flag. Note that eBPF interpreter is generic and knows nothing about pseudo insns. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/filter.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include') diff --git a/include/linux/filter.h b/include/linux/filter.h index 4ffc0958d85e..ca95abd2bed1 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -145,6 +145,12 @@ struct bpf_prog_aux; .off = 0, \ .imm = ((__u64) (IMM)) >> 32 }) +#define BPF_PSEUDO_MAP_FD 1 + +/* pseudo BPF_LD_IMM64 insn used to refer to process-local map_fd */ +#define BPF_LD_MAP_FD(DST, MAP_FD) \ + BPF_LD_IMM64_RAW(DST, BPF_PSEUDO_MAP_FD, MAP_FD) + /* Short form of mov based on type, BPF_X: dst_reg = src_reg, BPF_K: dst_reg = imm32 */ #define BPF_MOV64_RAW(TYPE, DST, SRC, IMM) \ -- cgit v1.2.3 From 17a5267067f3c372fec9ffb798d6eaba6b5e6a4c Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:17:06 -0700 Subject: 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 Signed-off-by: David S. Miller --- include/linux/bpf.h | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) (limited to 'include') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 9dfeb36f8971..3cf91754a957 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -46,6 +46,31 @@ void bpf_register_map_type(struct bpf_map_type_list *tl); void bpf_map_put(struct bpf_map *map); struct bpf_map *bpf_map_get(struct fd f); +/* function argument constraints */ +enum bpf_arg_type { + ARG_ANYTHING = 0, /* any argument is ok */ + + /* 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 */ +}; + +/* 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 */ +}; + /* 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 @@ -53,11 +78,33 @@ struct bpf_map *bpf_map_get(struct fd f); struct bpf_func_proto { u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5); bool gpl_only; + 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 }; struct bpf_verifier_ops { /* return eBPF function prototype for verification */ const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id); + + /* 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); }; struct bpf_prog_type_list { -- cgit v1.2.3