diff options
| -rw-r--r-- | Documentation/networking/filter.txt | 13 | ||||
| -rw-r--r-- | include/linux/filter.h | 1 | ||||
| -rw-r--r-- | include/uapi/linux/filter.h | 3 | ||||
| -rw-r--r-- | net/core/filter.c | 12 | ||||
| -rw-r--r-- | tools/net/bpf_exp.l | 1 | ||||
| -rw-r--r-- | tools/net/bpf_exp.y | 11 |
6 files changed, 39 insertions, 2 deletions
diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt index 81f940f4e884..82e1cb0b3da8 100644 --- a/Documentation/networking/filter.txt +++ b/Documentation/networking/filter.txt @@ -281,6 +281,7 @@ Possible BPF extensions are shown in the following table: cpu raw_smp_processor_id() vlan_tci vlan_tx_tag_get(skb) vlan_pr vlan_tx_tag_present(skb) + rand prandom_u32() These extensions can also be prefixed with '#'. Examples for low-level BPF: @@ -308,6 +309,18 @@ Examples for low-level BPF: ret #-1 drop: ret #0 +** icmp random packet sampling, 1 in 4 + ldh [12] + jne #0x800, drop + ldb [23] + jneq #1, drop + # get a random uint32 number + ld rand + mod #4 + jneq #1, drop + ret #-1 + drop: ret #0 + ** SECCOMP filter example: ld [4] /* offsetof(struct seccomp_data, arch) */ diff --git a/include/linux/filter.h b/include/linux/filter.h index 024fd03e5d18..759abf78dd61 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -223,6 +223,7 @@ enum { BPF_S_ANC_VLAN_TAG, BPF_S_ANC_VLAN_TAG_PRESENT, BPF_S_ANC_PAY_OFFSET, + BPF_S_ANC_RANDOM, }; #endif /* __LINUX_FILTER_H__ */ diff --git a/include/uapi/linux/filter.h b/include/uapi/linux/filter.h index 8eb9ccaa5b48..253b4d42cf2b 100644 --- a/include/uapi/linux/filter.h +++ b/include/uapi/linux/filter.h @@ -130,7 +130,8 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ #define SKF_AD_VLAN_TAG 44 #define SKF_AD_VLAN_TAG_PRESENT 48 #define SKF_AD_PAY_OFFSET 52 -#define SKF_AD_MAX 56 +#define SKF_AD_RANDOM 56 +#define SKF_AD_MAX 60 #define SKF_NET_OFF (-0x100000) #define SKF_LL_OFF (-0x200000) diff --git a/net/core/filter.c b/net/core/filter.c index cd58614660cf..78a636e60a0b 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -643,6 +643,12 @@ static u64 __get_raw_cpu_id(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) return raw_smp_processor_id(); } +/* note that this only generates 32-bit random numbers */ +static u64 __get_random_u32(u64 ctx, u64 A, u64 X, u64 r4, u64 r5) +{ + return (u64)prandom_u32(); +} + /* Register mappings for user programs. */ #define A_REG 0 #define X_REG 7 @@ -779,6 +785,7 @@ static bool convert_bpf_extensions(struct sock_filter *fp, case SKF_AD_OFF + SKF_AD_NLATTR: case SKF_AD_OFF + SKF_AD_NLATTR_NEST: case SKF_AD_OFF + SKF_AD_CPU: + case SKF_AD_OFF + SKF_AD_RANDOM: /* arg1 = ctx */ insn->code = BPF_ALU64 | BPF_MOV | BPF_X; insn->a_reg = ARG1_REG; @@ -812,6 +819,9 @@ static bool convert_bpf_extensions(struct sock_filter *fp, case SKF_AD_OFF + SKF_AD_CPU: insn->imm = __get_raw_cpu_id - __bpf_call_base; break; + case SKF_AD_OFF + SKF_AD_RANDOM: + insn->imm = __get_random_u32 - __bpf_call_base; + break; } break; @@ -1362,6 +1372,7 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen) ANCILLARY(VLAN_TAG); ANCILLARY(VLAN_TAG_PRESENT); ANCILLARY(PAY_OFFSET); + ANCILLARY(RANDOM); } /* ancillary operation unknown or unsupported */ @@ -1746,6 +1757,7 @@ void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to) [BPF_S_ANC_VLAN_TAG] = BPF_LD|BPF_B|BPF_ABS, [BPF_S_ANC_VLAN_TAG_PRESENT] = BPF_LD|BPF_B|BPF_ABS, [BPF_S_ANC_PAY_OFFSET] = BPF_LD|BPF_B|BPF_ABS, + [BPF_S_ANC_RANDOM] = BPF_LD|BPF_B|BPF_ABS, [BPF_S_LD_W_LEN] = BPF_LD|BPF_W|BPF_LEN, [BPF_S_LD_W_IND] = BPF_LD|BPF_W|BPF_IND, [BPF_S_LD_H_IND] = BPF_LD|BPF_H|BPF_IND, diff --git a/tools/net/bpf_exp.l b/tools/net/bpf_exp.l index bf7be77ddd62..833a96611da6 100644 --- a/tools/net/bpf_exp.l +++ b/tools/net/bpf_exp.l @@ -92,6 +92,7 @@ extern void yyerror(const char *str); "#"?("cpu") { return K_CPU; } "#"?("vlan_tci") { return K_VLANT; } "#"?("vlan_pr") { return K_VLANP; } +"#"?("rand") { return K_RAND; } ":" { return ':'; } "," { return ','; } diff --git a/tools/net/bpf_exp.y b/tools/net/bpf_exp.y index d15efc989ef5..e6306c51c26f 100644 --- a/tools/net/bpf_exp.y +++ b/tools/net/bpf_exp.y @@ -56,7 +56,7 @@ static void bpf_set_jmp_label(char *label, enum jmp_type type); %token OP_LDXI %token K_PKT_LEN K_PROTO K_TYPE K_NLATTR K_NLATTR_NEST K_MARK K_QUEUE K_HATYPE -%token K_RXHASH K_CPU K_IFIDX K_VLANT K_VLANP K_POFF +%token K_RXHASH K_CPU K_IFIDX K_VLANT K_VLANP K_POFF K_RAND %token ':' ',' '[' ']' '(' ')' 'x' 'a' '+' 'M' '*' '&' '#' '%' @@ -164,6 +164,9 @@ ldb | OP_LDB K_POFF { bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0, SKF_AD_OFF + SKF_AD_PAY_OFFSET); } + | OP_LDB K_RAND { + bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0, + SKF_AD_OFF + SKF_AD_RANDOM); } ; ldh @@ -212,6 +215,9 @@ ldh | OP_LDH K_POFF { bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0, SKF_AD_OFF + SKF_AD_PAY_OFFSET); } + | OP_LDH K_RAND { + bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0, + SKF_AD_OFF + SKF_AD_RANDOM); } ; ldi @@ -265,6 +271,9 @@ ld | OP_LD K_POFF { bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0, SKF_AD_OFF + SKF_AD_PAY_OFFSET); } + | OP_LD K_RAND { + bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0, + SKF_AD_OFF + SKF_AD_RANDOM); } | OP_LD 'M' '[' number ']' { bpf_set_curr_instr(BPF_LD | BPF_MEM, 0, 0, $4); } | OP_LD '[' 'x' '+' number ']' { |