From 69d7feb651c4c3443665fb271207ec6364bc7250 Mon Sep 17 00:00:00 2001
From: Martin Teichmann <martin.teichmann@gmail.com>
Date: Sat, 25 Feb 2023 15:53:45 +0000
Subject: [PATCH] fix setting bits from data
---
ebpfcat/ebpf.py | 62 +++++++++++++++++++++++---------------------
ebpfcat/ebpf_test.py | 10 +++++++
2 files changed, 42 insertions(+), 30 deletions(-)
diff --git a/ebpfcat/ebpf.py b/ebpfcat/ebpf.py
index b74a64e..106f0be 100644
--- a/ebpfcat/ebpf.py
+++ b/ebpfcat/ebpf.py
@@ -968,38 +968,40 @@ class Memory(Expression):
def _set(self, value):
opcode = Opcode.STX
- if isinstance(self.fmt, tuple):
- pos, bits = self.fmt
- self.fmt = "B"
- if bits == 1:
- try:
- if value:
- value = self | (1 << pos)
- else:
- value = self & ~(1 << pos)
- except AssembleError:
- with ebpf.wtmp:
+ with ExitStack() as exitStack:
+ if isinstance(self.fmt, tuple):
+ pos, bits = self.fmt
+ self.fmt = "B"
+ if bits == 1:
+ try:
+ if value:
+ value = self | (1 << pos)
+ else:
+ value = self & ~(1 << pos)
+ except AssembleError:
+ exitStack.enter_context(self.ebpf.wtmp)
with value as Else:
- ebpf.wtmp = self | (1 << pos)
+ self.ebpf.wtmp = self | (1 << pos)
with Else:
- ebpf.wtmp = self & ~(1 << pos)
- else:
- mask = ((1 << bits) - 1) << pos
- value = (mask & (value << pos) | ~mask & self)
- elif isinstance(value, IAdd) and len(self.fmt) == 1:
- value = value.value
- opcode = Opcode.XADD
- elif not isinstance(value, Expression):
- if self.fmt == "x":
- value = Constant(self.ebpf, value)
- else:
- value = Constant(self.ebpf,
- *unpack(self.fmt, pack(self.fmt[-1], value)))
- if self.fmt == "x" and not value.fixed:
- value *= Expression.FIXED_BASE
- elif self.fmt != "x" and value.fixed:
- value /= Expression.FIXED_BASE
- with ExitStack() as exitStack:
+ self.ebpf.wtmp = self & ~(1 << pos)
+ value = self.ebpf.wtmp
+ else:
+ mask = ((1 << bits) - 1) << pos
+ value = (mask & (value << pos) | ~mask & self)
+ elif isinstance(value, IAdd) and len(self.fmt) == 1:
+ value = value.value
+ opcode = Opcode.XADD
+ elif not isinstance(value, Expression):
+ if self.fmt == "x":
+ value = Constant(self.ebpf, value)
+ else:
+ value = Constant(
+ self.ebpf,
+ *unpack(self.fmt, pack(self.fmt[-1], value)))
+ if self.fmt == "x" and not value.fixed:
+ value *= Expression.FIXED_BASE
+ elif self.fmt != "x" and value.fixed:
+ value /= Expression.FIXED_BASE
if isinstance(self.address, Sum):
dst = self.address.left.no
offset = self.address.right.value
diff --git a/ebpfcat/ebpf_test.py b/ebpfcat/ebpf_test.py
index aa81111..01b61ac 100644
--- a/ebpfcat/ebpf_test.py
+++ b/ebpfcat/ebpf_test.py
@@ -316,6 +316,8 @@ class Tests(TestCase):
with e.b:
e.a = 0
+ e.a = e.b
+
self.assertEqual(e.opcodes, [
Instruction(opcode=O.LD+O.B, dst=0, src=10, off=-1, imm=0),
Instruction(opcode=O.JSET, dst=0, src=0, off=1, imm=32),
@@ -343,6 +345,14 @@ class Tests(TestCase):
Instruction(opcode=O.JMP, dst=0, src=0, off=3, imm=0),
Instruction(opcode=O.LD+O.B, dst=0, src=10, off=-1, imm=0),
Instruction(opcode=O.AND, dst=0, src=0, off=0, imm=-33),
+ Instruction(opcode=O.STX+O.B, dst=10, src=0, off=-1, imm=0),
+ Instruction(opcode=O.LD+O.B, dst=2, src=10, off=-2, imm=0),
+ Instruction(opcode=O.JSET, dst=2, src=0, off=3, imm=120),
+ Instruction(opcode=O.LD+O.B, dst=0, src=10, off=-1, imm=0),
+ Instruction(opcode=O.AND, dst=0, src=0, off=0, imm=-33),
+ Instruction(opcode=O.JMP, dst=0, src=0, off=2, imm=0),
+ Instruction(opcode=O.LD+O.B, dst=0, src=10, off=-1, imm=0),
+ Instruction(opcode=O.OR, dst=0, src=0, off=0, imm=32),
Instruction(opcode=O.B+O.STX, dst=10, src=0, off=-1, imm=0)])
def test_local_subprog(self):
--
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