{ "variable-offset ctx access", .insns = { /* Get an unknown value */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), /* add it to skb. We now have either &skb->len or * &skb->pkt_type, but we don't know which */ BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_2), /* dereference it */ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, 0), BPF_EXIT_INSN(), }, .errstr = "variable ctx access var_off=(0x0; 0x4)", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, { "variable-offset stack access", .insns = { /* Fill the top 8 bytes of the stack */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 8), /* add it to fp. We now have either fp-4 or fp-8, but * we don't know which */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* dereference it */ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0), BPF_EXIT_INSN(), }, .errstr = "variable stack access var_off=(0xfffffffffffffff8; 0x4)", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, { "indirect variable-offset stack access, unbounded", .insns = { BPF_MOV64_IMM(BPF_REG_2, 6), BPF_MOV64_IMM(BPF_REG_3, 28), /* Fill the top 16 bytes of the stack. */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0), BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value. */ BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_1, offsetof(struct bpf_sock_ops, bytes_received)), /* Check the lower bound but don't check the upper one. */ BPF_JMP_IMM(BPF_JSLT, BPF_REG_4, 0, 4), /* Point the lower bound to initialized stack. Offset is now in range * from fp-16 to fp+0x7fffffffffffffef, i.e. max value is unbounded. */ BPF_ALU64_IMM(BPF_SUB, BPF_REG_4, 16), BPF_ALU64_REG(BPF_ADD, BPF_REG_4, BPF_REG_10), BPF_MOV64_IMM(BPF_REG_5, 8), /* Dereference it indirectly. */ BPF_EMIT_CALL(BPF_FUNC_getsockopt), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .errstr = "R4 unbounded indirect variable offset stack access", .result = REJECT, .prog_type = BPF_PROG_TYPE_SOCK_OPS, }, { "indirect variable-offset stack access, max out of bound", .insns = { /* Fill the top 8 bytes of the stack */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 8), /* add it to fp. We now have either fp-4 or fp-8, but * we don't know which */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* dereference it indirectly */ BPF_LD_MAP_FD(BPF_REG_1, 0), BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .fixup_map_hash_8b = { 5 }, .errstr = "R2 max value is outside of stack bound", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, { "indirect variable-offset stack access, min out of bound", .insns = { /* Fill the top 8 bytes of the stack */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 516), /* add it to fp. We now have either fp-516 or fp-512, but * we don't know which */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* dereference it indirectly */ BPF_LD_MAP_FD(BPF_REG_1, 0), BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .fixup_map_hash_8b = { 5 }, .errstr = "R2 min value is outside of stack bound", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, { "indirect variable-offset stack access, max_off+size > max_initialized", .insns = { /* Fill only the second from top 8 bytes of the stack. */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0), /* Get an unknown value. */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned. */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16), /* Add it to fp. We now have either fp-12 or fp-16, but we don't know * which. fp-12 size 8 is partially uninitialized stack. */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* Dereference it indirectly. */ BPF_LD_MAP_FD(BPF_REG_1, 0), BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .fixup_map_hash_8b = { 5 }, .errstr = "invalid indirect read from stack var_off", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, { "indirect variable-offset stack access, min_off < min_initialized", .insns = { /* Fill only the top 8 bytes of the stack. */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned. */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16), /* Add it to fp. We now have either fp-12 or fp-16, but we don't know * which. fp-16 size 8 is partially uninitialized stack. */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* Dereference it indirectly. */ BPF_LD_MAP_FD(BPF_REG_1, 0), BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .fixup_map_hash_8b = { 5 }, .errstr = "invalid indirect read from stack var_off", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, { "indirect variable-offset stack access, priv vs unpriv", .insns = { /* Fill the top 16 bytes of the stack. */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0), BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value. */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned. */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16), /* Add it to fp. We now have either fp-12 or fp-16, we don't know * which, but either way it points to initialized stack. */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* Dereference it indirectly. */ BPF_LD_MAP_FD(BPF_REG_1, 0), BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .fixup_map_hash_8b = { 6 }, .errstr_unpriv = "R2 stack pointer arithmetic goes out of range, prohibited for !root", .result_unpriv = REJECT, .result = ACCEPT, .prog_type = BPF_PROG_TYPE_CGROUP_SKB, }, { "indirect variable-offset stack access, uninitialized", .insns = { BPF_MOV64_IMM(BPF_REG_2, 6), BPF_MOV64_IMM(BPF_REG_3, 28), /* Fill the top 16 bytes of the stack. */ BPF_ST_MEM(BPF_W, BPF_REG_10, -16, 0), BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value. */ BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1, 0), /* Make it small and 4-byte aligned. */ BPF_ALU64_IMM(BPF_AND, BPF_REG_4, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_4, 16), /* Add it to fp. We now have either fp-12 or fp-16, we don't know * which, but either way it points to initialized stack. */ BPF_ALU64_REG(BPF_ADD, BPF_REG_4, BPF_REG_10), BPF_MOV64_IMM(BPF_REG_5, 8), /* Dereference it indirectly. */ BPF_EMIT_CALL(BPF_FUNC_getsockopt), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .errstr = "invalid indirect read from stack var_off", .result = REJECT, .prog_type = BPF_PROG_TYPE_SOCK_OPS, }, { "indirect variable-offset stack access, ok", .insns = { /* Fill the top 16 bytes of the stack. */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0), BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), /* Get an unknown value. */ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), /* Make it small and 4-byte aligned. */ BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 16), /* Add it to fp. We now have either fp-12 or fp-16, we don't know * which, but either way it points to initialized stack. */ BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), /* Dereference it indirectly. */ BPF_LD_MAP_FD(BPF_REG_1, 0), BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN(), }, .fixup_map_hash_8b = { 6 }, .result = ACCEPT, .prog_type = BPF_PROG_TYPE_LWT_IN, },