Function report

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:kernel\bpf\verifier.c Create Date:2022-07-28 13:04:45
Last Modify:2022-05-19 20:02:10 Copyright©Brick
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Annotation kernel can get tool activityDownload SCCTChinese

Name:vert load instructions that access fields of a context type into a* sequence of instructions that access fields of the underlying structure:* struct __sk_buff -> struct sk_buff* struct bpf_sock_ops -> struct sock

Proto:static int convert_ctx_accesses(struct bpf_verifier_env *env)

Type:int

Parameter:

TypeParameterName
struct bpf_verifier_env *env
8748  ops = ops
8749  delta = 0
8750  insn_cnt = Number of filter blocks
8757  If gen_prologue || seen_direct_write Then
8758  If Not gen_prologue Then
8759  verbose(env, "bpf verifier is misconfigured\n")
8760  Return -EINVAL
8762  cnt = gen_prologue(insn_buf, seen_direct_write, BPF program being verified )
8764  If cnt >= ARRAY_SIZE - get the number of elements in array @arr*@arr: array to be sized(insn_buf) Then
8765  verbose(env, "bpf verifier is misconfigured\n")
8766  Return -EINVAL
8767  Else if cnt Then
8768  new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt)
8769  If Not new_prog Then Return -ENOMEM
8772  BPF program being verified = new_prog
8773  delta += cnt - 1
8777  If bpf_prog_is_dev_bound( Auxiliary fields ) Then Return 0
8780  insn = insnsi + delta
8782  When i < insn_cnt cycle
8785  If opcode == ( BPF_LDX | BPF_MEM | 8-bit ) || opcode == ( BPF_LDX | BPF_MEM | 16-bit ) || opcode == ( BPF_LDX | BPF_MEM | 32-bit ) || opcode == ( BPF_LDX | BPF_MEM | double word (64-bit) ) Then type = BPF_READ
8790  Else if opcode == ( BPF_STX | BPF_MEM | 8-bit ) || opcode == ( BPF_STX | BPF_MEM | 16-bit ) || opcode == ( BPF_STX | BPF_MEM | 32-bit ) || opcode == ( BPF_STX | BPF_MEM | double word (64-bit) ) Then type = BPF_WRITE
8795  Else Continue
8798  If type == BPF_WRITE && stack slot to be cleared Then
8800  struct bpf_insn patch[] = {Memory store, *(uint *) (dst_reg + off16) = imm32 (double word (64-bit) , BPF_REG_FP, stack slot to be cleared , 0), * insn, }
8815  cnt = ARRAY_SIZE - get the number of elements in array @arr*@arr: array to be sized(patch)
8816  new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt)
8817  If Not new_prog Then Return -ENOMEM
8820  delta += cnt - 1
8821  BPF program being verified = new_prog
8822  insn = insnsi + i + delta
8823  Continue
8827  Case pointer type for load/store insns == g points to bpf_context
8828  If Not convert_ctx_access Then Continue
8830  convert_ctx_access = convert_ctx_access
8831  Break
8832  Case pointer type for load/store insns == g points to struct bpf_sock
8833  Case pointer type for load/store insns == g points to sock_common
8836  Case pointer type for load/store insns == g points to struct tcp_sock
8839  Case pointer type for load/store insns == g points to struct xdp_sock
8842  Case pointer type for load/store insns == g points to kernel struct
8843  If type == BPF_WRITE Then
8844  verbose(env, "Writes through BTF pointers are not allowed\n")
8845  Return -EINVAL
8847  opcode = BPF_LDX | unused opcode to mark special load instruction. Same as BPF_ABS | ld/ldx fields ( opcode )
8848  num_exentries++
8849  Continue
8850  Default
8851  Continue
8854  ctx_field_size = the ctx field size for load insn, maybe 0
8855  size = BPF_LDST_BYTES(insn)
8862  is_narrower_load = size < ctx_field_size
8863  size_default = bpf_ctx_off_adjust_machine(ctx_field_size)
8864  off = signed offset
8865  If is_narrower_load Then
8868  If type == BPF_WRITE Then
8869  verbose(env, "bpf verifier narrow ctx access misconfigured\n")
8870  Return -EINVAL
8873  size_code = 16-bit
8874  If ctx_field_size == 4 Then size_code = 32-bit
8876  Else if ctx_field_size == 8 Then size_code = double word (64-bit)
8879  signed offset = off & ~(size_default - 1)
8880  opcode = BPF_LDX | BPF_MEM | size_code
8883  target_size = 0
8884  cnt = convert_ctx_access(type, insn, insn_buf, BPF program being verified , & target_size)
8886  If cnt == 0 || cnt >= ARRAY_SIZE - get the number of elements in array @arr*@arr: array to be sized(insn_buf) || ctx_field_size && Not target_size Then
8888  verbose(env, "bpf verifier is misconfigured\n")
8889  Return -EINVAL
8892  If is_narrower_load && size < target_size Then
8912  new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt)
8913  If Not new_prog Then Return -ENOMEM
8916  delta += cnt - 1
8919  BPF program being verified = new_prog
8920  insn = insnsi + i + delta
8923  Return 0
Caller
NameDescribe
bpf_check