| /* |
| * Copyright 2024, The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "apf_interpreter.h" |
| |
| #include <string.h> /* For memcmp, memcpy, memset */ |
| |
| #if __GNUC__ >= 7 || __clang__ |
| #define FALLTHROUGH __attribute__((fallthrough)) |
| #else |
| #define FALLTHROUGH |
| #endif |
| |
| typedef enum { False, True } Boolean; |
| |
| /* Begin include of apf_defs.h */ |
| typedef int8_t s8; |
| typedef int16_t s16; |
| typedef int32_t s32; |
| |
| typedef uint8_t u8; |
| typedef uint16_t u16; |
| typedef uint32_t u32; |
| |
| typedef enum { |
| error_program = -2, |
| error_packet = -1, |
| nomatch = False, |
| match = True, |
| } match_result_type; |
| |
| #define ETH_P_IP 0x0800 |
| #define ETH_P_IPV6 0x86DD |
| |
| #define ETH_HLEN 14 |
| #define IPV4_HLEN 20 |
| #define IPV6_HLEN 40 |
| #define TCP_HLEN 20 |
| #define UDP_HLEN 8 |
| |
| #define FUNC(x) x; x |
| /* End include of apf_defs.h */ |
| /* Begin include of apf.h */ |
| /* |
| * Copyright 2024, The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef ANDROID_APF_APF_H |
| #define ANDROID_APF_APF_H |
| |
| /* A brief overview of APF: |
| * |
| * APF machine is composed of: |
| * 1. A read-only program consisting of bytecodes as described below. |
| * 2. Two 32-bit registers, called R0 and R1. |
| * 3. Sixteen 32-bit temporary memory slots (cleared between packets). |
| * 4. A read-only packet. |
| * 5. An optional read-write transmit buffer. |
| * The program is executed by the interpreter below and parses the packet |
| * to determine if the application processor (AP) should be woken up to |
| * handle the packet or if it can be dropped. The program may also choose |
| * to allocate/transmit/deallocate the transmit buffer. |
| * |
| * APF bytecode description: |
| * |
| * The APF interpreter uses big-endian byte order for loads from the packet |
| * and for storing immediates in instructions. |
| * |
| * Each instruction starts with a byte composed of: |
| * Top 5 bits form "opcode" field, see *_OPCODE defines below. |
| * Next 2 bits form "size field", which indicates the length of an immediate |
| * value which follows the first byte. Values in this field: |
| * 0 => immediate value is 0 and no bytes follow. |
| * 1 => immediate value is 1 byte big. |
| * 2 => immediate value is 2 bytes big. |
| * 3 => immediate value is 4 bytes big. |
| * Bottom bit forms "register" field, which (usually) indicates which register |
| * this instruction operates on. |
| * |
| * There are four main categories of instructions: |
| * Load instructions |
| * These instructions load byte(s) of the packet into a register. |
| * They load either 1, 2 or 4 bytes, as determined by the "opcode" field. |
| * They load into the register specified by the "register" field. |
| * The immediate value that follows the first byte of the instruction is |
| * the byte offset from the beginning of the packet to load from. |
| * There are "indexing" loads which add the value in R1 to the byte offset |
| * to load from. The "opcode" field determines which loads are "indexing". |
| * Arithmetic instructions |
| * These instructions perform simple operations, like addition, on register |
| * values. The result of these instructions is always written into R0. One |
| * argument of the arithmetic operation is R0's value. The other argument |
| * of the arithmetic operation is determined by the "register" field: |
| * If the "register" field is 0 then the immediate value following |
| * the first byte of the instruction is used as the other argument |
| * to the arithmetic operation. |
| * If the "register" field is 1 then R1's value is used as the other |
| * argument to the arithmetic operation. |
| * Conditional jump instructions |
| * These instructions compare register R0's value with another value, and if |
| * the comparison succeeds, jump (i.e. adjust the program counter). The |
| * immediate value that follows the first byte of the instruction |
| * represents the jump target offset, i.e. the value added to the program |
| * counter if the comparison succeeds. The other value compared is |
| * determined by the "register" field: |
| * If the "register" field is 0 then another immediate value |
| * follows the jump target offset. This immediate value is of the |
| * same size as the jump target offset, and represents the value |
| * to compare against. |
| * If the "register" field is 1 then register R1's value is |
| * compared against. |
| * The type of comparison (e.g. equal to, greater than etc) is determined |
| * by the "opcode" field. The comparison interprets both values being |
| * compared as unsigned values. |
| * Miscellaneous instructions |
| * Instructions for: |
| * - allocating/transmitting/deallocating transmit buffer |
| * - building the transmit packet (copying bytes into it) |
| * - read/writing data section |
| * |
| * Miscellaneous details: |
| * |
| * Pre-filled temporary memory slot values |
| * When the APF program begins execution, six of the sixteen memory slots |
| * are pre-filled by the interpreter with values that may be useful for |
| * programs: |
| * #0 to #7 are zero initialized. |
| * Slot #8 is initialized with apf version (on APF >4). |
| * Slot #9 this is slot #15 with greater resolution (1/16384ths of a second) |
| * Slot #10 starts at zero, implicitly used as tx buffer output pointer. |
| * Slot #11 contains the size (in bytes) of the APF program. |
| * Slot #12 contains the total size of the APF program + data. |
| * Slot #13 is filled with the IPv4 header length. This value is calculated |
| * by loading the first byte of the IPv4 header and taking the |
| * bottom 4 bits and multiplying their value by 4. This value is |
| * set to zero if the first 4 bits after the link layer header are |
| * not 4, indicating not IPv4. |
| * Slot #14 is filled with size of the packet in bytes, including the |
| * ethernet link-layer header. |
| * Slot #15 is filled with the filter age in seconds. This is the number of |
| * seconds since the host installed the program. This may |
| * be used by filters that should have a particular lifetime. For |
| * example, it can be used to rate-limit particular packets to one |
| * every N seconds. |
| * Special jump targets: |
| * When an APF program executes a jump to the byte immediately after the last |
| * byte of the progam (i.e., one byte past the end of the program), this |
| * signals the program has completed and determined the packet should be |
| * passed to the AP. |
| * When an APF program executes a jump two bytes past the end of the program, |
| * this signals the program has completed and determined the packet should |
| * be dropped. |
| * Jump if byte sequence doesn't match: |
| * This is a special instruction to facilitate matching long sequences of |
| * bytes in the packet. Initially it is encoded like a conditional jump |
| * instruction with two exceptions: |
| * The first byte of the instruction is always followed by two immediate |
| * fields: The first immediate field is the jump target offset like other |
| * conditional jump instructions. The second immediate field specifies the |
| * number of bytes to compare. |
| * These two immediate fields are followed by a sequence of bytes. These |
| * bytes are compared with the bytes in the packet starting from the |
| * position specified by the value of the register specified by the |
| * "register" field of the instruction. |
| */ |
| |
| /* Number of temporary memory slots, see ldm/stm instructions. */ |
| #define MEMORY_ITEMS 16 |
| /* Upon program execution, some temporary memory slots are prefilled: */ |
| |
| typedef union { |
| struct { |
| u32 pad[8]; /* 0..7 */ |
| u32 apf_version; /* 8: Initialized with apf_version() */ |
| u32 filter_age_16384ths; /* 9: Age since filter installed in 1/16384 seconds. */ |
| u32 tx_buf_offset; /* 10: Offset in tx_buf where next byte will be written */ |
| u32 program_size; /* 11: Size of program (in bytes) */ |
| u32 ram_len; /* 12: Total size of program + data, ie. ram_len */ |
| u32 ipv4_header_size; /* 13: 4*([APF_FRAME_HEADER_SIZE]&15) */ |
| u32 packet_size; /* 14: Size of packet in bytes. */ |
| u32 filter_age; /* 15: Age since filter installed in seconds. */ |
| } named; |
| u32 slot[MEMORY_ITEMS]; |
| } memory_type; |
| |
| /* ---------------------------------------------------------------------------------------------- */ |
| |
| /* Standard opcodes. */ |
| |
| /* Unconditionally pass (if R=0) or drop (if R=1) packet and optionally increment counter. |
| * An optional non-zero unsigned immediate value can be provided to encode the counter number. |
| * The counter is located (-4 * counter number) bytes from the end of the data region. |
| * It is a U32 big-endian value and is always incremented by 1. |
| * This is more or less equivalent to: lddw R0, -4*N; add R0, 1; stdw R0, -4*N; {pass,drop} |
| * e.g. "pass", "pass 1", "drop", "drop 1" |
| */ |
| #define PASSDROP_OPCODE 0 |
| |
| #define LDB_OPCODE 1 /* Load 1 byte from immediate offset, e.g. "ldb R0, [5]" */ |
| #define LDH_OPCODE 2 /* Load 2 bytes from immediate offset, e.g. "ldh R0, [5]" */ |
| #define LDW_OPCODE 3 /* Load 4 bytes from immediate offset, e.g. "ldw R0, [5]" */ |
| #define LDBX_OPCODE 4 /* Load 1 byte from immediate offset plus register, e.g. "ldbx R0, [5+R0]" */ |
| #define LDHX_OPCODE 5 /* Load 2 bytes from immediate offset plus register, e.g. "ldhx R0, [5+R0]" */ |
| #define LDWX_OPCODE 6 /* Load 4 bytes from immediate offset plus register, e.g. "ldwx R0, [5+R0]" */ |
| #define ADD_OPCODE 7 /* Add, e.g. "add R0,5" */ |
| #define MUL_OPCODE 8 /* Multiply, e.g. "mul R0,5" */ |
| #define DIV_OPCODE 9 /* Divide, e.g. "div R0,5" */ |
| #define AND_OPCODE 10 /* And, e.g. "and R0,5" */ |
| #define OR_OPCODE 11 /* Or, e.g. "or R0,5" */ |
| #define SH_OPCODE 12 /* Left shift, e.g. "sh R0, 5" or "sh R0, -5" (shifts right) */ |
| #define LI_OPCODE 13 /* Load signed immediate, e.g. "li R0,5" */ |
| #define JMP_OPCODE 14 /* Unconditional jump, e.g. "jmp label" */ |
| #define JEQ_OPCODE 15 /* Compare equal and branch, e.g. "jeq R0,5,label" */ |
| #define JNE_OPCODE 16 /* Compare not equal and branch, e.g. "jne R0,5,label" */ |
| #define JGT_OPCODE 17 /* Compare greater than and branch, e.g. "jgt R0,5,label" */ |
| #define JLT_OPCODE 18 /* Compare less than and branch, e.g. "jlt R0,5,label" */ |
| #define JSET_OPCODE 19 /* Compare any bits set and branch, e.g. "jset R0,5,label" */ |
| #define JBSMATCH_OPCODE 20 /* Compare byte sequence [R=0 not] equal, e.g. "jbsne R0,2,label,0x1122" */ |
| /* NOTE: Only APFv6+ implements R=1 'jbseq' version */ |
| #define EXT_OPCODE 21 /* Immediate value is one of *_EXT_OPCODE */ |
| #define LDDW_OPCODE 22 /* Load 4 bytes from data address (register + signed imm): "lddw R0, [5+R1]" */ |
| /* LDDW/STDW in APFv6+ *mode* load/store from counter specified in imm. */ |
| #define STDW_OPCODE 23 /* Store 4 bytes to data address (register + signed imm): "stdw R0, [5+R1]" */ |
| |
| /* Write 1, 2 or 4 byte immediate to the output buffer and auto-increment the output buffer pointer. |
| * Immediate length field specifies size of write. R must be 0. imm_len != 0. |
| * e.g. "write 5" |
| */ |
| #define WRITE_OPCODE 24 |
| |
| /* Copy bytes from input packet/APF program/data region to output buffer and |
| * auto-increment the output buffer pointer. |
| * Register bit is used to specify the source of data copy. |
| * R=0 means copy from packet. |
| * R=1 means copy from APF program/data region. |
| * The source offset is stored in imm1, copy length is stored in u8 imm2. |
| * e.g. "pktcopy 0, 16" or "datacopy 0, 16" |
| */ |
| #define PKTDATACOPY_OPCODE 25 |
| |
| /* ---------------------------------------------------------------------------------------------- */ |
| |
| /* Extended opcodes. */ |
| /* These all have an opcode of EXT_OPCODE and specify the actual opcode in the immediate field. */ |
| |
| #define LDM_EXT_OPCODE 0 /* Load from temporary memory, e.g. "ldm R0,5" */ |
| /* Values 0-15 represent loading the different temporary memory slots. */ |
| #define STM_EXT_OPCODE 16 /* Store to temporary memory, e.g. "stm R0,5" */ |
| /* Values 16-31 represent storing to the different temporary memory slots. */ |
| #define NOT_EXT_OPCODE 32 /* Not, e.g. "not R0" */ |
| #define NEG_EXT_OPCODE 33 /* Negate, e.g. "neg R0" */ |
| #define SWAP_EXT_OPCODE 34 /* Swap, e.g. "swap R0,R1" */ |
| #define MOV_EXT_OPCODE 35 /* Move, e.g. "move R0,R1" */ |
| |
| /* Allocate writable output buffer. |
| * R=0: register R0 specifies the length |
| * R=1: length provided in u16 imm2 |
| * e.g. "allocate R0" or "allocate 123" |
| * On failure automatically executes 'pass 3' |
| */ |
| #define ALLOCATE_EXT_OPCODE 36 |
| /* Transmit and deallocate the buffer (transmission can be delayed until the program |
| * terminates). Length of buffer is the output buffer pointer (0 means discard). |
| * R=1 iff udp style L4 checksum |
| * u8 imm2 - ip header offset from start of buffer (255 for non-ip packets) |
| * u8 imm3 - offset from start of buffer to store L4 checksum (255 for no L4 checksum) |
| * u8 imm4 - offset from start of buffer to begin L4 checksum calculation (present iff imm3 != 255) |
| * u16 imm5 - partial checksum value to include in L4 checksum (present iff imm3 != 255) |
| * "e.g. transmit" |
| */ |
| #define TRANSMIT_EXT_OPCODE 37 |
| /* Write 1, 2 or 4 byte value from register to the output buffer and auto-increment the |
| * output buffer pointer. |
| * e.g. "ewrite1 r0" or "ewrite2 r1" |
| */ |
| #define EWRITE1_EXT_OPCODE 38 |
| #define EWRITE2_EXT_OPCODE 39 |
| #define EWRITE4_EXT_OPCODE 40 |
| |
| /* Copy bytes from input packet/APF program/data region to output buffer and |
| * auto-increment the output buffer pointer. |
| * Register bit is used to specify the source of data copy. |
| * R=0 means copy from packet. |
| * R=1 means copy from APF program/data region. |
| * The source offset is stored in R0, copy length is stored in u8 imm2 or R1. |
| * e.g. "epktcopy r0, 16", "edatacopy r0, 16", "epktcopy r0, r1", "edatacopy r0, r1" |
| */ |
| #define EPKTDATACOPYIMM_EXT_OPCODE 41 |
| #define EPKTDATACOPYR1_EXT_OPCODE 42 |
| /* Jumps if the UDP payload content (starting at R0) does [not] match one |
| * of the specified QNAMEs in question records, applying case insensitivity. |
| * SAFE version PASSES corrupt packets, while the other one DROPS. |
| * R=0/1 meaning 'does not match'/'matches' |
| * R0: Offset to UDP payload content |
| * imm1: Extended opcode |
| * imm2: Jump label offset |
| * imm3(u8): Question type (PTR/SRV/TXT/A/AAAA) |
| * imm4(bytes): null terminated list of null terminated LV-encoded QNAMEs |
| * e.g.: "jdnsqeq R0,label,0xc,\002aa\005local\0\0", "jdnsqne R0,label,0xc,\002aa\005local\0\0" |
| */ |
| #define JDNSQMATCH_EXT_OPCODE 43 |
| #define JDNSQMATCHSAFE_EXT_OPCODE 45 |
| /* Jumps if the UDP payload content (starting at R0) does [not] match one |
| * of the specified NAMEs in answers/authority/additional records, applying |
| * case insensitivity. |
| * SAFE version PASSES corrupt packets, while the other one DROPS. |
| * R=0/1 meaning 'does not match'/'matches' |
| * R0: Offset to UDP payload content |
| * imm1: Extended opcode |
| * imm2: Jump label offset |
| * imm3(bytes): null terminated list of null terminated LV-encoded NAMEs |
| * e.g.: "jdnsaeq R0,label,0xc,\002aa\005local\0\0", "jdnsane R0,label,0xc,\002aa\005local\0\0" |
| */ |
| #define JDNSAMATCH_EXT_OPCODE 44 |
| #define JDNSAMATCHSAFE_EXT_OPCODE 46 |
| |
| /* Jump if register is [not] one of the list of values |
| * R bit - specifies the register (R0/R1) to test |
| * imm1: Extended opcode |
| * imm2: Jump label offset |
| * imm3(u8): top 5 bits - number of following u8/be16/be32 values - 1 |
| * middle 2 bits - 1..4 length of immediates |
| * bottom 1 bit - =0 jmp if in set, =1 if not in set |
| * imm4(imm3 * 1/2/3/4 bytes): the *UNIQUE* values to compare against |
| */ |
| #define JONEOF_EXT_OPCODE 47 |
| |
| /* This extended opcode is used to implement PKTDATACOPY_OPCODE */ |
| #define PKTDATACOPYIMM_EXT_OPCODE 65536 |
| |
| #define EXTRACT_OPCODE(i) (((i) >> 3) & 31) |
| #define EXTRACT_REGISTER(i) ((i) & 1) |
| #define EXTRACT_IMM_LENGTH(i) (((i) >> 1) & 3) |
| |
| #endif /* ANDROID_APF_APF_H */ |
| /* End include of apf.h */ |
| /* Begin include of apf_utils.h */ |
| static u32 read_be16(const u8* buf) { |
| return buf[0] * 256u + buf[1]; |
| } |
| |
| static void store_be16(u8* const buf, const u16 v) { |
| buf[0] = (u8)(v >> 8); |
| buf[1] = (u8)v; |
| } |
| |
| static u8 uppercase(u8 c) { |
| return (c >= 'a') && (c <= 'z') ? c - ('a' - 'A') : c; |
| } |
| /* End include of apf_utils.h */ |
| /* Begin include of apf_dns.h */ |
| /** |
| * Compares a (Q)NAME starting at udp[*ofs] with the target name. |
| * |
| * @param needle - non-NULL - pointer to DNS encoded target name to match against. |
| * example: [11]_googlecast[4]_tcp[5]local[0] (where [11] is a byte with value 11) |
| * @param needle_bound - non-NULL - points at first invalid byte past needle. |
| * @param udp - non-NULL - pointer to the start of the UDP payload (DNS header). |
| * @param udp_len - length of the UDP payload. |
| * @param ofs - non-NULL - pointer to the offset of the beginning of the (Q)NAME. |
| * On non-error return will be updated to point to the first unread offset, |
| * ie. the next position after the (Q)NAME. |
| * |
| * @return 1 if matched, 0 if not matched, -1 if error in packet, -2 if error in program. |
| */ |
| FUNC(match_result_type apf_internal_match_single_name(const u8* needle, |
| const u8* const needle_bound, |
| const u8* const udp, |
| const u32 udp_len, |
| u32* const ofs)) { |
| u32 first_unread_offset = *ofs; |
| Boolean is_qname_match = True; |
| int lvl; |
| |
| /* DNS names are <= 255 characters including terminating 0, since >= 1 char + '.' per level => max. 127 levels */ |
| for (lvl = 1; lvl <= 127; ++lvl) { |
| if (*ofs >= udp_len) return error_packet; |
| u8 v = udp[(*ofs)++]; |
| if (v >= 0xC0) { /* RFC 1035 4.1.4 - handle message compression */ |
| if (*ofs >= udp_len) return error_packet; |
| u8 w = udp[(*ofs)++]; |
| if (*ofs > first_unread_offset) first_unread_offset = *ofs; |
| u32 new_ofs = (v - 0xC0) * 256 + w; |
| if (new_ofs >= *ofs) return error_packet; /* RFC 1035 4.1.4 allows only backward pointers */ |
| *ofs = new_ofs; |
| } else if (v > 63) { |
| return error_packet; /* RFC 1035 2.3.4 - label size is 1..63. */ |
| } else if (v) { |
| u8 label_size = v; |
| if (*ofs + label_size > udp_len) return error_packet; |
| if (needle >= needle_bound) return error_program; |
| if (is_qname_match) { |
| u8 len = *needle++; |
| if (len == label_size) { |
| if (needle + label_size > needle_bound) return error_program; |
| while (label_size--) { |
| u8 w = udp[(*ofs)++]; |
| is_qname_match &= (uppercase(w) == *needle++); |
| } |
| } else { |
| if (len != 0xFF) is_qname_match = False; |
| *ofs += label_size; |
| } |
| } else { |
| is_qname_match = False; |
| *ofs += label_size; |
| } |
| } else { /* reached the end of the name */ |
| if (first_unread_offset > *ofs) *ofs = first_unread_offset; |
| return (is_qname_match && *needle == 0) ? match : nomatch; |
| } |
| } |
| return error_packet; /* too many dns domain name levels */ |
| } |
| |
| /** |
| * Check if DNS packet contains any of the target names with the provided |
| * question_type. |
| * |
| * @param needles - non-NULL - pointer to DNS encoded target nameS to match against. |
| * example: [3]foo[3]com[0][3]bar[3]net[0][0] -- note ends with an extra NULL byte. |
| * @param needle_bound - non-NULL - points at first invalid byte past needles. |
| * @param udp - non-NULL - pointer to the start of the UDP payload (DNS header). |
| * @param udp_len - length of the UDP payload. |
| * @param question_type - question type to match against or -1 to match answers. |
| * |
| * @return 1 if matched, 0 if not matched, -1 if error in packet, -2 if error in program. |
| */ |
| FUNC(match_result_type apf_internal_match_names(const u8* needles, |
| const u8* const needle_bound, |
| const u8* const udp, |
| const u32 udp_len, |
| const int question_type)) { |
| if (udp_len < 12) return error_packet; /* lack of dns header */ |
| |
| /* dns header: be16 tid, flags, num_{questions,answers,authority,additional} */ |
| u32 num_questions = read_be16(udp + 4); |
| u32 num_answers = read_be16(udp + 6) + read_be16(udp + 8) + read_be16(udp + 10); |
| |
| /* loop until we hit final needle, which is a null byte */ |
| while (True) { |
| if (needles >= needle_bound) return error_program; |
| if (!*needles) return nomatch; /* we've run out of needles without finding a match */ |
| u32 ofs = 12; /* dns header is 12 bytes */ |
| u32 i; |
| /* match questions */ |
| for (i = 0; i < num_questions; ++i) { |
| match_result_type m = apf_internal_match_single_name(needles, needle_bound, udp, udp_len, &ofs); |
| if (m < nomatch) return m; |
| if (ofs + 2 > udp_len) return error_packet; |
| int qtype = (int)read_be16(udp + ofs); |
| ofs += 4; /* skip be16 qtype & qclass */ |
| if (question_type == -1) continue; |
| if (m == nomatch) continue; |
| if (qtype == 0xFF /* QTYPE_ANY */ || qtype == question_type) return match; |
| } |
| /* match answers */ |
| if (question_type == -1) for (i = 0; i < num_answers; ++i) { |
| match_result_type m = apf_internal_match_single_name(needles, needle_bound, udp, udp_len, &ofs); |
| if (m < nomatch) return m; |
| ofs += 8; /* skip be16 type, class & be32 ttl */ |
| if (ofs + 2 > udp_len) return error_packet; |
| ofs += 2 + read_be16(udp + ofs); /* skip be16 rdata length field, plus length bytes */ |
| if (m == match) return match; |
| } |
| /* move needles pointer to the next needle. */ |
| do { |
| u8 len = *needles++; |
| if (len == 0xFF) continue; |
| if (len > 63) return error_program; |
| needles += len; |
| if (needles >= needle_bound) return error_program; |
| } while (*needles); |
| needles++; /* skip the NULL byte at the end of *a* DNS name */ |
| } |
| } |
| /* End include of apf_dns.h */ |
| /* Begin include of apf_checksum.h */ |
| /** |
| * Calculate big endian 16-bit sum of a buffer (max 128kB), |
| * then fold and negate it, producing a 16-bit result in [0..FFFE]. |
| */ |
| FUNC(u16 apf_internal_calc_csum(u32 sum, const u8* const buf, const s32 len)) { |
| s32 i; |
| for (i = 0; i < len; ++i) sum += buf[i] * ((i & 1) ? 1 : 256); |
| |
| sum = (sum & 0xFFFF) + (sum >> 16); /* max after this is 1FFFE */ |
| u16 csum = sum + (sum >> 16); |
| return ~csum; /* assuming sum > 0 on input, this is in [0..FFFE] */ |
| } |
| |
| static u16 fix_udp_csum(u16 csum) { |
| return csum ? csum : 0xFFFF; |
| } |
| |
| /** |
| * Calculate and store packet checksums and return dscp. |
| * |
| * @param pkt - pointer to the very start of the to-be-transmitted packet, |
| * ie. the start of the ethernet header (if one is present) |
| * WARNING: at minimum 266 bytes of buffer pointed to by 'pkt' pointer |
| * *MUST* be writable. |
| * (IPv4 header checksum is a 2 byte value, 10 bytes after ip_ofs, |
| * which has a maximum value of 254. Thus 254[ip_ofs] + 10 + 2[u16] = 266) |
| * |
| * @param len - length of the packet (this may be < 266). |
| * @param ip_ofs - offset from beginning of pkt to IPv4 or IPv6 header: |
| * IP version detected based on top nibble of this byte, |
| * for IPv4 we will calculate and store IP header checksum, |
| * but only for the first 20 bytes of the header, |
| * prior to calling this the IPv4 header checksum field |
| * must be initialized to the partial checksum of the IPv4 |
| * options (0 if none) |
| * 255 means there is no IP header (for example ARP) |
| * DSCP will be retrieved from this IP header (0 if none). |
| * @param partial_csum - additional value to include in L4 checksum |
| * @param csum_start - offset from beginning of pkt to begin L4 checksum |
| * calculation (until end of pkt specified by len) |
| * @param csum_ofs - offset from beginning of pkt to store L4 checksum |
| * 255 means do not calculate/store L4 checksum |
| * @param udp - True iff we should generate a UDP style L4 checksum (0 -> 0xFFFF) |
| * |
| * @return 6-bit DSCP value [0..63], garbage on parse error. |
| */ |
| FUNC(int apf_internal_csum_and_return_dscp(u8* const pkt, const s32 len, const u8 ip_ofs, |
| const u16 partial_csum, const u8 csum_start, const u8 csum_ofs, const Boolean udp)) { |
| if (csum_ofs < 255) { |
| /* note that apf_internal_calc_csum() treats negative lengths as zero */ |
| u32 csum = apf_internal_calc_csum(partial_csum, pkt + csum_start, len - csum_start); |
| if (udp) csum = fix_udp_csum(csum); |
| store_be16(pkt + csum_ofs, csum); |
| } |
| if (ip_ofs < 255) { |
| u8 ip = pkt[ip_ofs] >> 4; |
| if (ip == 4) { |
| store_be16(pkt + ip_ofs + 10, apf_internal_calc_csum(0, pkt + ip_ofs, IPV4_HLEN)); |
| return pkt[ip_ofs + 1] >> 2; /* DSCP */ |
| } else if (ip == 6) { |
| return (read_be16(pkt + ip_ofs) >> 6) & 0x3F; /* DSCP */ |
| } |
| } |
| return 0; |
| } |
| /* End include of apf_checksum.h */ |
| |
| /* User hook for interpreter debug tracing. */ |
| #ifdef APF_TRACE_HOOK |
| extern void APF_TRACE_HOOK(u32 pc, const u32* regs, const u8* program, |
| u32 program_len, const u8 *packet, u32 packet_len, |
| const u32* memory, u32 ram_len); |
| #else |
| #define APF_TRACE_HOOK(pc, regs, program, program_len, packet, packet_len, memory, memory_len) \ |
| do { /* nop*/ \ |
| } while (0) |
| #endif |
| |
| /* Return code indicating "packet" should accepted. */ |
| #define PASS_PACKET 1 |
| /* Return code indicating "packet" should be dropped. */ |
| #define DROP_PACKET 0 |
| /* Verify an internal condition and accept packet if it fails. */ |
| #define ASSERT_RETURN(c) if (!(c)) return PASS_PACKET |
| /* If "c" is of an unsigned type, generate a compile warning that gets promoted to an error. */ |
| /* This makes bounds checking simpler because ">= 0" can be avoided. Otherwise adding */ |
| /* superfluous ">= 0" with unsigned expressions generates compile warnings. */ |
| #define ENFORCE_UNSIGNED(c) ((c)==(u32)(c)) |
| |
| u32 apf_version(void) { |
| return 20240315; |
| } |
| |
| typedef struct { |
| void *caller_ctx; /* Passed in to interpreter, passed through to alloc/transmit. */ |
| u8* tx_buf; /* The output buffer pointer */ |
| u32 tx_buf_len; /* The length of the output buffer */ |
| u8* program; /* Pointer to program/data buffer */ |
| u32 program_len; /* Length of the program */ |
| u32 ram_len; /* Length of the entire apf program/data region */ |
| const u8* packet; /* Pointer to input packet buffer */ |
| u32 packet_len; /* Length of the input packet buffer */ |
| /* u8 err_code; // */ |
| u8 v6; /* Set to 1 by first jmpdata (APFv6+) instruction */ |
| u32 pc; /* Program counter. */ |
| u32 R[2]; /* Register values. */ |
| memory_type mem; /* Memory slot values. */ |
| } apf_context; |
| |
| FUNC(int apf_internal_do_transmit_buffer(apf_context* ctx, u32 pkt_len, u8 dscp)) { |
| int ret = apf_transmit_buffer(ctx->caller_ctx, ctx->tx_buf, pkt_len, dscp); |
| ctx->tx_buf = NULL; |
| ctx->tx_buf_len = 0; |
| return ret; |
| } |
| |
| static int do_discard_buffer(apf_context* ctx) { |
| return apf_internal_do_transmit_buffer(ctx, 0 /* pkt_len */, 0 /* dscp */); |
| } |
| |
| /* Decode the imm length, does not do range checking. */ |
| /* But note that program is at least 20 bytes shorter than ram, so first few */ |
| /* immediates can always be safely decoded without exceeding ram buffer. */ |
| static u32 decode_imm(apf_context* ctx, u32 length) { |
| u32 i, v = 0; |
| for (i = 0; i < length; ++i) v = (v << 8) | ctx->program[ctx->pc++]; |
| return v; |
| } |
| |
| #define DECODE_U8() (ctx->program[ctx->pc++]) |
| |
| static u16 decode_be16(apf_context* ctx) { |
| u16 v = ctx->program[ctx->pc++]; |
| v <<= 8; |
| v |= ctx->program[ctx->pc++]; |
| return v; |
| } |
| |
| static int do_apf_run(apf_context* ctx) { |
| /* Is offset within ram bounds? */ |
| #define IN_RAM_BOUNDS(p) (ENFORCE_UNSIGNED(p) && (p) < ctx->ram_len) |
| /* Is offset within packet bounds? */ |
| #define IN_PACKET_BOUNDS(p) (ENFORCE_UNSIGNED(p) && (p) < ctx->packet_len) |
| /* Is access to offset |p| length |size| within data bounds? */ |
| #define IN_DATA_BOUNDS(p, size) (ENFORCE_UNSIGNED(p) && \ |
| ENFORCE_UNSIGNED(size) && \ |
| (p) + (size) <= ctx->ram_len && \ |
| (p) + (size) >= (p)) /* catch wraparounds */ |
| /* Accept packet if not within ram bounds */ |
| #define ASSERT_IN_RAM_BOUNDS(p) ASSERT_RETURN(IN_RAM_BOUNDS(p)) |
| /* Accept packet if not within packet bounds */ |
| #define ASSERT_IN_PACKET_BOUNDS(p) ASSERT_RETURN(IN_PACKET_BOUNDS(p)) |
| /* Accept packet if not within data bounds */ |
| #define ASSERT_IN_DATA_BOUNDS(p, size) ASSERT_RETURN(IN_DATA_BOUNDS(p, size)) |
| |
| /* Counters start at end of RAM and count *backwards* so this array takes negative integers. */ |
| u32 *counter = (u32*)(ctx->program + ctx->ram_len); |
| |
| ASSERT_IN_PACKET_BOUNDS(ETH_HLEN); |
| /* Only populate if IP version is IPv4. */ |
| if ((ctx->packet[ETH_HLEN] & 0xf0) == 0x40) { |
| ctx->mem.named.ipv4_header_size = (ctx->packet[ETH_HLEN] & 15) * 4; |
| } |
| /* Count of instructions remaining to execute. This is done to ensure an */ |
| /* upper bound on execution time. It should never be hit and is only for */ |
| /* safety. Initialize to the number of bytes in the program which is an */ |
| /* upper bound on the number of instructions in the program. */ |
| u32 instructions_remaining = ctx->program_len; |
| |
| /* Is access to offset |p| length |size| within output buffer bounds? */ |
| #define IN_OUTPUT_BOUNDS(p, size) (ENFORCE_UNSIGNED(p) && \ |
| ENFORCE_UNSIGNED(size) && \ |
| (p) + (size) <= ctx->tx_buf_len && \ |
| (p) + (size) >= (p)) |
| /* Accept packet if not write within allocated output buffer */ |
| #define ASSERT_IN_OUTPUT_BOUNDS(p, size) ASSERT_RETURN(IN_OUTPUT_BOUNDS(p, size)) |
| |
| do { |
| APF_TRACE_HOOK(ctx->pc, ctx->R, ctx->program, ctx->program_len, |
| ctx->packet, ctx->packet_len, ctx->mem.slot, ctx->ram_len); |
| if (ctx->pc == ctx->program_len + 1) return DROP_PACKET; |
| if (ctx->pc >= ctx->program_len) return PASS_PACKET; |
| |
| const u8 bytecode = ctx->program[ctx->pc++]; |
| const u32 opcode = EXTRACT_OPCODE(bytecode); |
| const u32 reg_num = EXTRACT_REGISTER(bytecode); |
| #define REG (ctx->R[reg_num]) |
| #define OTHER_REG (ctx->R[reg_num ^ 1]) |
| /* All instructions have immediate fields, so load them now. */ |
| const u32 len_field = EXTRACT_IMM_LENGTH(bytecode); |
| u32 imm = 0; |
| s32 signed_imm = 0; |
| if (len_field != 0) { |
| const u32 imm_len = 1 << (len_field - 1); |
| imm = decode_imm(ctx, imm_len); /* 1st imm, at worst bytes 1-4 past opcode/program_len */ |
| /* Sign extend imm into signed_imm. */ |
| signed_imm = (s32)(imm << ((4 - imm_len) * 8)); |
| signed_imm >>= (4 - imm_len) * 8; |
| } |
| |
| /* See comment at ADD_OPCODE for the reason for ARITH_REG/arith_imm/arith_signed_imm. */ |
| #define ARITH_REG (ctx->R[reg_num & ctx->v6]) |
| u32 arith_imm = (ctx->v6) ? (len_field ? imm : OTHER_REG) : (reg_num ? ctx->R[1] : imm); |
| s32 arith_signed_imm = (ctx->v6) ? (len_field ? signed_imm : (s32)OTHER_REG) : (reg_num ? (s32)ctx->R[1] : signed_imm); |
| |
| u32 pktcopy_src_offset = 0; /* used for various pktdatacopy opcodes */ |
| switch (opcode) { |
| case PASSDROP_OPCODE: { /* APFv6+ */ |
| if (len_field > 2) return PASS_PACKET; /* max 64K counters (ie. imm < 64K) */ |
| if (imm) { |
| if (4 * imm > ctx->ram_len) return PASS_PACKET; |
| counter[-(s32)imm]++; |
| } |
| return reg_num ? DROP_PACKET : PASS_PACKET; |
| } |
| case LDB_OPCODE: |
| case LDH_OPCODE: |
| case LDW_OPCODE: |
| case LDBX_OPCODE: |
| case LDHX_OPCODE: |
| case LDWX_OPCODE: { |
| u32 offs = imm; |
| /* Note: this can overflow and actually decrease offs. */ |
| if (opcode >= LDBX_OPCODE) offs += ctx->R[1]; |
| ASSERT_IN_PACKET_BOUNDS(offs); |
| u32 load_size = 0; |
| switch (opcode) { |
| case LDB_OPCODE: |
| case LDBX_OPCODE: |
| load_size = 1; |
| break; |
| case LDH_OPCODE: |
| case LDHX_OPCODE: |
| load_size = 2; |
| break; |
| case LDW_OPCODE: |
| case LDWX_OPCODE: |
| load_size = 4; |
| break; |
| /* Immediately enclosing switch statement guarantees */ |
| /* opcode cannot be any other value. */ |
| } |
| const u32 end_offs = offs + (load_size - 1); |
| /* Catch overflow/wrap-around. */ |
| ASSERT_RETURN(end_offs >= offs); |
| ASSERT_IN_PACKET_BOUNDS(end_offs); |
| u32 val = 0; |
| while (load_size--) val = (val << 8) | ctx->packet[offs++]; |
| REG = val; |
| break; |
| } |
| case JMP_OPCODE: |
| if (reg_num && !ctx->v6) { /* APFv6+ */ |
| /* First invocation of APFv6 jmpdata instruction */ |
| counter[-1] = 0x12345678; /* endianness marker */ |
| counter[-2]++; /* total packets ++ */ |
| ctx->v6 = (u8)True; |
| } |
| /* This can jump backwards. Infinite looping prevented by instructions_remaining. */ |
| ctx->pc += imm; |
| break; |
| case JEQ_OPCODE: |
| case JNE_OPCODE: |
| case JGT_OPCODE: |
| case JLT_OPCODE: |
| case JSET_OPCODE: { |
| /* with len_field == 0, we have imm == 0 and thus a jmp +0, ie. a no-op */ |
| if (len_field == 0) break; |
| /* Load second immediate field. */ |
| u32 cmp_imm = 0; |
| if (reg_num == 1) { |
| cmp_imm = ctx->R[1]; |
| } else { |
| u32 cmp_imm_len = 1 << (len_field - 1); |
| cmp_imm = decode_imm(ctx, cmp_imm_len); /* 2nd imm, at worst 8 bytes past prog_len */ |
| } |
| switch (opcode) { |
| case JEQ_OPCODE: if (ctx->R[0] == cmp_imm) ctx->pc += imm; break; |
| case JNE_OPCODE: if (ctx->R[0] != cmp_imm) ctx->pc += imm; break; |
| case JGT_OPCODE: if (ctx->R[0] > cmp_imm) ctx->pc += imm; break; |
| case JLT_OPCODE: if (ctx->R[0] < cmp_imm) ctx->pc += imm; break; |
| case JSET_OPCODE: if (ctx->R[0] & cmp_imm) ctx->pc += imm; break; |
| } |
| break; |
| } |
| case JBSMATCH_OPCODE: { |
| /* with len_field == 0, we have imm == cmp_imm == 0 and thus a jmp +0, ie. a no-op */ |
| if (len_field == 0) break; |
| /* Load second immediate field. */ |
| u32 cmp_imm_len = 1 << (len_field - 1); |
| u32 cmp_imm = decode_imm(ctx, cmp_imm_len); /* 2nd imm, at worst 8 bytes past prog_len */ |
| /* cmp_imm is size in bytes of data to compare. */ |
| /* pc is offset of program bytes to compare. */ |
| /* imm is jump target offset. */ |
| /* R0 is offset of packet bytes to compare. */ |
| if (cmp_imm > 0xFFFF) return PASS_PACKET; |
| Boolean do_jump = !reg_num; |
| /* pc < program_len < ram_len < 2GiB, thus pc + cmp_imm cannot wrap */ |
| if (!IN_RAM_BOUNDS(ctx->pc + cmp_imm - 1)) return PASS_PACKET; |
| ASSERT_IN_PACKET_BOUNDS(ctx->R[0]); |
| const u32 last_packet_offs = ctx->R[0] + cmp_imm - 1; |
| ASSERT_RETURN(last_packet_offs >= ctx->R[0]); |
| ASSERT_IN_PACKET_BOUNDS(last_packet_offs); |
| do_jump ^= !memcmp(ctx->program + ctx->pc, ctx->packet + ctx->R[0], cmp_imm); |
| /* skip past comparison bytes */ |
| ctx->pc += cmp_imm; |
| if (do_jump) ctx->pc += imm; |
| break; |
| } |
| /* There is a difference in APFv4 and APFv6 arithmetic behaviour! */ |
| /* APFv4: R[0] op= Rbit ? R[1] : imm; (and it thus doesn't make sense to have R=1 && len_field>0) */ |
| /* APFv6+: REG op= len_field ? imm : OTHER_REG; (note: this is *DIFFERENT* with R=1 len_field==0) */ |
| /* Furthermore APFv4 uses unsigned imm (except SH), while APFv6 uses signed_imm for ADD/AND/SH. */ |
| case ADD_OPCODE: ARITH_REG += (ctx->v6) ? (u32)arith_signed_imm : arith_imm; break; |
| case MUL_OPCODE: ARITH_REG *= arith_imm; break; |
| case AND_OPCODE: ARITH_REG &= (ctx->v6) ? (u32)arith_signed_imm : arith_imm; break; |
| case OR_OPCODE: ARITH_REG |= arith_imm; break; |
| case DIV_OPCODE: { /* see above comment! */ |
| const u32 div_operand = arith_imm; |
| ASSERT_RETURN(div_operand); |
| ARITH_REG /= div_operand; |
| break; |
| } |
| case SH_OPCODE: { /* see above comment! */ |
| if (arith_signed_imm >= 0) |
| ARITH_REG <<= arith_signed_imm; |
| else |
| ARITH_REG >>= -arith_signed_imm; |
| break; |
| } |
| case LI_OPCODE: |
| REG = (u32)signed_imm; |
| break; |
| case PKTDATACOPY_OPCODE: |
| pktcopy_src_offset = imm; |
| imm = PKTDATACOPYIMM_EXT_OPCODE; |
| FALLTHROUGH; |
| case EXT_OPCODE: |
| if (/* imm >= LDM_EXT_OPCODE && -- but note imm is u32 and LDM_EXT_OPCODE is 0 */ |
| imm < (LDM_EXT_OPCODE + MEMORY_ITEMS)) { |
| REG = ctx->mem.slot[imm - LDM_EXT_OPCODE]; |
| } else if (imm >= STM_EXT_OPCODE && imm < (STM_EXT_OPCODE + MEMORY_ITEMS)) { |
| ctx->mem.slot[imm - STM_EXT_OPCODE] = REG; |
| } else switch (imm) { |
| case NOT_EXT_OPCODE: REG = ~REG; break; |
| case NEG_EXT_OPCODE: REG = -REG; break; |
| case MOV_EXT_OPCODE: REG = OTHER_REG; break; |
| case SWAP_EXT_OPCODE: { |
| u32 tmp = REG; |
| REG = OTHER_REG; |
| OTHER_REG = tmp; |
| break; |
| } |
| case ALLOCATE_EXT_OPCODE: |
| ASSERT_RETURN(ctx->tx_buf == NULL); |
| if (reg_num == 0) { |
| ctx->tx_buf_len = REG; |
| } else { |
| ctx->tx_buf_len = decode_be16(ctx); /* 2nd imm, at worst 6 B past prog_len */ |
| } |
| /* checksumming functions requires minimum 266 byte buffer for correctness */ |
| if (ctx->tx_buf_len < 266) ctx->tx_buf_len = 266; |
| ctx->tx_buf = apf_allocate_buffer(ctx->caller_ctx, ctx->tx_buf_len); |
| if (!ctx->tx_buf) { /* allocate failure */ |
| ctx->tx_buf_len = 0; |
| counter[-3]++; |
| return PASS_PACKET; |
| } |
| memset(ctx->tx_buf, 0, ctx->tx_buf_len); |
| ctx->mem.named.tx_buf_offset = 0; |
| break; |
| case TRANSMIT_EXT_OPCODE: |
| ASSERT_RETURN(ctx->tx_buf); |
| u32 pkt_len = ctx->mem.named.tx_buf_offset; |
| /* If pkt_len > allocate_buffer_len, it means sth. wrong */ |
| /* happened and the tx_buf should be deallocated. */ |
| if (pkt_len > ctx->tx_buf_len) { |
| do_discard_buffer(ctx); |
| return PASS_PACKET; |
| } |
| /* tx_buf_len cannot be large because we'd run out of RAM, */ |
| /* so the above unsigned comparison effectively guarantees casting pkt_len */ |
| /* to a signed value does not result in it going negative. */ |
| u8 ip_ofs = DECODE_U8(); /* 2nd imm, at worst 5 B past prog_len */ |
| u8 csum_ofs = DECODE_U8(); /* 3rd imm, at worst 6 B past prog_len */ |
| u8 csum_start = 0; |
| u16 partial_csum = 0; |
| if (csum_ofs < 255) { |
| csum_start = DECODE_U8(); /* 4th imm, at worst 7 B past prog_len */ |
| partial_csum = decode_be16(ctx); /* 5th imm, at worst 9 B past prog_len */ |
| } |
| int dscp = apf_internal_csum_and_return_dscp(ctx->tx_buf, (s32)pkt_len, ip_ofs, |
| partial_csum, csum_start, csum_ofs, |
| (Boolean)reg_num); |
| int ret = apf_internal_do_transmit_buffer(ctx, pkt_len, dscp); |
| if (ret) { counter[-4]++; return PASS_PACKET; } /* transmit failure */ |
| break; |
| case EPKTDATACOPYIMM_EXT_OPCODE: /* 41 */ |
| case EPKTDATACOPYR1_EXT_OPCODE: /* 42 */ |
| pktcopy_src_offset = ctx->R[0]; |
| FALLTHROUGH; |
| case PKTDATACOPYIMM_EXT_OPCODE: { /* 65536 */ |
| u32 copy_len = ctx->R[1]; |
| if (imm != EPKTDATACOPYR1_EXT_OPCODE) { |
| copy_len = DECODE_U8(); /* 2nd imm, at worst 8 bytes past prog_len */ |
| } |
| ASSERT_RETURN(ctx->tx_buf); |
| u32 dst_offs = ctx->mem.named.tx_buf_offset; |
| ASSERT_IN_OUTPUT_BOUNDS(dst_offs, copy_len); |
| if (reg_num == 0) { /* copy from packet */ |
| ASSERT_IN_PACKET_BOUNDS(pktcopy_src_offset); |
| const u32 last_packet_offs = pktcopy_src_offset + copy_len - 1; |
| ASSERT_RETURN(last_packet_offs >= pktcopy_src_offset); |
| ASSERT_IN_PACKET_BOUNDS(last_packet_offs); |
| memcpy(ctx->tx_buf + dst_offs, ctx->packet + pktcopy_src_offset, copy_len); |
| } else { /* copy from data */ |
| ASSERT_IN_RAM_BOUNDS(pktcopy_src_offset + copy_len - 1); |
| memcpy(ctx->tx_buf + dst_offs, ctx->program + pktcopy_src_offset, copy_len); |
| } |
| dst_offs += copy_len; |
| ctx->mem.named.tx_buf_offset = dst_offs; |
| break; |
| } |
| case JDNSQMATCH_EXT_OPCODE: /* 43 */ |
| case JDNSAMATCH_EXT_OPCODE: /* 44 */ |
| case JDNSQMATCHSAFE_EXT_OPCODE: /* 45 */ |
| case JDNSAMATCHSAFE_EXT_OPCODE: { /* 46 */ |
| const u32 imm_len = 1 << (len_field - 1); /* EXT_OPCODE, thus len_field > 0 */ |
| u32 jump_offs = decode_imm(ctx, imm_len); /* 2nd imm, at worst 8 B past prog_len */ |
| int qtype = -1; |
| if (imm & 1) { /* JDNSQMATCH & JDNSQMATCHSAFE are *odd* extended opcodes */ |
| qtype = DECODE_U8(); /* 3rd imm, at worst 9 bytes past prog_len */ |
| } |
| u32 udp_payload_offset = ctx->R[0]; |
| match_result_type match_rst = apf_internal_match_names(ctx->program + ctx->pc, |
| ctx->program + ctx->program_len, |
| ctx->packet + udp_payload_offset, |
| ctx->packet_len - udp_payload_offset, |
| qtype); |
| if (match_rst == error_program) return PASS_PACKET; |
| if (match_rst == error_packet) { |
| counter[-5]++; /* increment error dns packet counter */ |
| return (imm >= JDNSQMATCHSAFE_EXT_OPCODE) ? PASS_PACKET : DROP_PACKET; |
| } |
| while (ctx->pc + 1 < ctx->program_len && |
| (ctx->program[ctx->pc] || ctx->program[ctx->pc + 1])) { |
| ctx->pc++; |
| } |
| ctx->pc += 2; /* skip the final double 0 needle end */ |
| /* relies on reg_num in {0,1} and match_rst being {False=0, True=1} */ |
| if (!(reg_num ^ (u32)match_rst)) ctx->pc += jump_offs; |
| break; |
| } |
| case EWRITE1_EXT_OPCODE: |
| case EWRITE2_EXT_OPCODE: |
| case EWRITE4_EXT_OPCODE: { |
| ASSERT_RETURN(ctx->tx_buf); |
| const u32 write_len = 1 << (imm - EWRITE1_EXT_OPCODE); |
| ASSERT_IN_OUTPUT_BOUNDS(ctx->mem.named.tx_buf_offset, write_len); |
| u32 i; |
| for (i = 0; i < write_len; ++i) { |
| ctx->tx_buf[ctx->mem.named.tx_buf_offset++] = |
| (u8)(REG >> (write_len - 1 - i) * 8); |
| } |
| break; |
| } |
| case JONEOF_EXT_OPCODE: { |
| const u32 imm_len = 1 << (len_field - 1); /* ext opcode len_field guaranteed > 0 */ |
| u32 jump_offs = decode_imm(ctx, imm_len); /* 2nd imm, at worst 8 B past prog_len */ |
| u8 imm3 = DECODE_U8(); /* 3rd imm, at worst 9 bytes past prog_len */ |
| Boolean jmp = imm3 & 1; /* =0 jmp on match, =1 jmp on no match */ |
| u8 len = ((imm3 >> 1) & 3) + 1; /* size [1..4] in bytes of an element */ |
| u8 cnt = (imm3 >> 3) + 1; /* number [1..32] of elements in set */ |
| if (ctx->pc + cnt * len > ctx->program_len) return PASS_PACKET; |
| while (cnt--) { |
| u32 v = 0; |
| int i; |
| for (i = 0; i < len; ++i) v = (v << 8) | DECODE_U8(); |
| if (REG == v) jmp ^= True; |
| } |
| if (jmp) ctx->pc += jump_offs; |
| return PASS_PACKET; |
| } |
| default: /* Unknown extended opcode */ |
| return PASS_PACKET; /* Bail out */ |
| } |
| break; |
| case LDDW_OPCODE: |
| case STDW_OPCODE: |
| if (ctx->v6) { |
| if (!imm) return PASS_PACKET; |
| if (imm > 0xFFFF) return PASS_PACKET; |
| if (imm * 4 > ctx->ram_len) return PASS_PACKET; |
| if (opcode == LDDW_OPCODE) { |
| REG = counter[-(s32)imm]; |
| } else { |
| counter[-(s32)imm] = REG; |
| } |
| } else { |
| u32 offs = OTHER_REG + (u32)signed_imm; |
| /* Negative offsets wrap around the end of the address space. */ |
| /* This allows us to efficiently access the end of the */ |
| /* address space with one-byte immediates without using %=. */ |
| if (offs & 0x80000000) offs += ctx->ram_len; /* unsigned overflow intended */ |
| u32 size = 4; |
| ASSERT_IN_DATA_BOUNDS(offs, size); |
| if (opcode == LDDW_OPCODE) { |
| u32 val = 0; |
| while (size--) val = (val << 8) | ctx->program[offs++]; |
| REG = val; |
| } else { |
| u32 val = REG; |
| while (size--) { |
| ctx->program[offs++] = (val >> 24); |
| val <<= 8; |
| } |
| } |
| } |
| break; |
| case WRITE_OPCODE: { |
| ASSERT_RETURN(ctx->tx_buf); |
| ASSERT_RETURN(len_field); |
| const u32 write_len = 1 << (len_field - 1); |
| ASSERT_IN_OUTPUT_BOUNDS(ctx->mem.named.tx_buf_offset, write_len); |
| u32 i; |
| for (i = 0; i < write_len; ++i) { |
| ctx->tx_buf[ctx->mem.named.tx_buf_offset++] = |
| (u8)(imm >> (write_len - 1 - i) * 8); |
| } |
| break; |
| } |
| default: /* Unknown opcode */ |
| return PASS_PACKET; /* Bail out */ |
| } |
| } while (instructions_remaining--); |
| return PASS_PACKET; |
| } |
| |
| int apf_run(void* ctx, u32* const program, const u32 program_len, |
| const u32 ram_len, const u8* const packet, |
| const u32 packet_len, const u32 filter_age_16384ths) { |
| /* Due to direct 32-bit read/write access to counters at end of ram */ |
| /* APFv6 interpreter requires program & ram_len to be 4 byte aligned. */ |
| if (3 & (uintptr_t)program) return PASS_PACKET; |
| if (3 & ram_len) return PASS_PACKET; |
| |
| /* We rely on ram_len + 65536 not overflowing, so require ram_len < 2GiB */ |
| /* Similarly LDDW/STDW have special meaning for negative ram offsets. */ |
| /* We also don't want garbage like program_len == 0xFFFFFFFF */ |
| if ((program_len | ram_len) >> 31) return PASS_PACKET; |
| |
| /* APFv6 requires at least 5 u32 counters at the end of ram, this makes counter[-5]++ valid */ |
| /* This cannot wrap due to previous check. */ |
| if (program_len + 20 > ram_len) return PASS_PACKET; |
| |
| apf_context apf_ctx = {}; |
| apf_ctx.caller_ctx = ctx; |
| apf_ctx.program = (u8*)program; |
| apf_ctx.program_len = program_len; |
| apf_ctx.ram_len = ram_len; |
| apf_ctx.packet = packet; |
| apf_ctx.packet_len = packet_len; |
| /* Fill in pre-filled memory slot values. */ |
| apf_ctx.mem.named.program_size = program_len; |
| apf_ctx.mem.named.ram_len = ram_len; |
| apf_ctx.mem.named.packet_size = packet_len; |
| apf_ctx.mem.named.apf_version = apf_version(); |
| apf_ctx.mem.named.filter_age = filter_age_16384ths >> 14; |
| apf_ctx.mem.named.filter_age_16384ths = filter_age_16384ths; |
| |
| int ret = do_apf_run(&apf_ctx); |
| if (apf_ctx.tx_buf) do_discard_buffer(&apf_ctx); |
| return ret; |
| } |
