From f51ab800758689a67c312742ffdf9116e1e178c0 Mon Sep 17 00:00:00 2001
From: Tamir Duberstein <tamird@gmail.com>
Date: Sun, 2 Mar 2025 08:25:52 -0500
Subject: [PATCH] perf_buffer: attempt to preserve provenance
In tests, provide write provenance.
---
aya/src/maps/perf/perf_buffer.rs | 216 ++++++++++++++++---------------
1 file changed, 113 insertions(+), 103 deletions(-)
diff --git a/aya/src/maps/perf/perf_buffer.rs b/aya/src/maps/perf/perf_buffer.rs
index e04e1e2c..3fa4b0dd 100644
--- a/aya/src/maps/perf/perf_buffer.rs
+++ b/aya/src/maps/perf/perf_buffer.rs
@@ -145,28 +145,24 @@ impl PerfBuffer {
return Err(PerfBufferError::NoBuffers);
}
let header = self.buf().as_ptr();
- let base = header as usize + self.page_size;
+ let base = unsafe { header.byte_add(self.page_size) };
let mut events = Events { read: 0, lost: 0 };
let mut buf_n = 0;
- let fill_buf = |start_off, base, mmap_size, out_buf: &mut [u8]| {
+ let fill_buf = |start_off, base: *const u8, mmap_size, out_buf: &mut [u8]| {
let len = out_buf.len();
let end = (start_off + len) % mmap_size;
let start = start_off % mmap_size;
if start < end {
- out_buf.copy_from_slice(unsafe {
- slice::from_raw_parts((base + start) as *const u8, len)
- });
+ out_buf.copy_from_slice(unsafe { slice::from_raw_parts(base.add(start), len) });
} else {
let size = mmap_size - start;
unsafe {
- out_buf[..size]
- .copy_from_slice(slice::from_raw_parts((base + start) as *const u8, size));
- out_buf[size..]
- .copy_from_slice(slice::from_raw_parts(base as *const u8, len - size));
+ out_buf[..size].copy_from_slice(slice::from_raw_parts(base.add(start), size));
+ out_buf[size..].copy_from_slice(slice::from_raw_parts(base, len - size));
}
}
};
@@ -227,11 +223,11 @@ impl PerfBuffer {
let buf = &mut buffers[buf_n];
let event_start = tail % self.size;
- let event =
- unsafe { ptr::read_unaligned((base + event_start) as *const perf_event_header) };
+ let event: perf_event_header =
+ unsafe { ptr::read_unaligned(base.byte_add(event_start).cast()) };
let event_size = event.size as usize;
- match read_event(event_start, event.type_, base, buf) {
+ match read_event(event_start, event.type_, base.cast(), buf) {
Ok(Some((read, lost))) => {
if read > 0 {
buf_n += 1;
@@ -290,14 +286,15 @@ mod tests {
data: [u8; PAGE_SIZE * 2],
}
- fn fake_mmap(buf: &MMappedBuf) {
+ fn fake_mmap(buf: &mut MMappedBuf) {
+ let buf: *mut _ = buf;
override_syscall(|call| match call {
Syscall::PerfEventOpen { .. } | Syscall::PerfEventIoctl { .. } => {
Ok(crate::MockableFd::mock_signed_fd().into())
}
call => panic!("unexpected syscall: {:?}", call),
});
- TEST_MMAP_RET.with(|ret| *ret.borrow_mut() = buf as *const _ as *mut _);
+ TEST_MMAP_RET.with(|ret| *ret.borrow_mut() = buf.cast());
}
#[test]
@@ -318,27 +315,25 @@ mod tests {
#[test]
fn test_no_out_bufs() {
- let mmapped_buf = MMappedBuf {
+ let mut mmapped_buf = MMappedBuf {
data: [0; PAGE_SIZE * 2],
};
- fake_mmap(&mmapped_buf);
+ fake_mmap(&mut mmapped_buf);
let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
+
assert_matches!(buf.read_events(&mut []), Err(PerfBufferError::NoBuffers))
}
#[test]
- #[cfg_attr(
- miri,
- ignore = "`unsafe { (*header).data_tail = tail as u64 };` is attempting a write access using using a tag that only grants SharedReadOnly permission"
- )]
fn test_no_events() {
- let mmapped_buf = MMappedBuf {
+ let mut mmapped_buf = MMappedBuf {
data: [0; PAGE_SIZE * 2],
};
- fake_mmap(&mmapped_buf);
+ fake_mmap(&mut mmapped_buf);
let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
+
let out_buf = BytesMut::with_capacity(4);
assert_eq!(
buf.read_events(&mut [out_buf]).unwrap(),
@@ -346,13 +341,18 @@ mod tests {
);
}
+ fn write<T: Debug>(mmapped_buf: &mut MMappedBuf, offset: usize, value: T) -> usize {
+ let dst: *mut _ = mmapped_buf;
+ let head = offset + mem::size_of::<T>();
+ unsafe {
+ ptr::write_unaligned(dst.byte_add(PAGE_SIZE + offset).cast(), value);
+ mmapped_buf.mmap_page.data_head = head as u64;
+ }
+ head
+ }
+
#[test]
fn test_read_first_lost() {
- let mut mmapped_buf = MMappedBuf {
- data: [0; PAGE_SIZE * 2],
- };
- fake_mmap(&mmapped_buf);
-
#[repr(C)]
#[derive(Debug)]
struct LostSamples {
@@ -361,18 +361,27 @@ mod tests {
count: u64,
}
- let evt = LostSamples {
- header: perf_event_header {
- type_: PERF_RECORD_LOST as u32,
- misc: 0,
- size: mem::size_of::<LostSamples>() as u16,
- },
- id: 1,
- count: 0xCAFEBABE,
+ let mut mmapped_buf = MMappedBuf {
+ data: [0; PAGE_SIZE * 2],
};
- write(&mut mmapped_buf, 0, evt);
+ write(
+ &mut mmapped_buf,
+ 0,
+ LostSamples {
+ header: perf_event_header {
+ type_: PERF_RECORD_LOST as u32,
+ misc: 0,
+ size: mem::size_of::<LostSamples>() as u16,
+ },
+ id: 1,
+ count: 0xCAFEBABE,
+ },
+ );
+
+ fake_mmap(&mut mmapped_buf);
let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
+
let out_buf = BytesMut::with_capacity(0);
let events = buf.read_events(&mut [out_buf]).unwrap();
assert_eq!(events.lost, 0xCAFEBABE);
@@ -385,28 +394,22 @@ mod tests {
value: T,
}
- fn write<T: Debug>(mmapped_buf: &mut MMappedBuf, offset: usize, value: T) -> usize {
- let dst: *mut _ = mmapped_buf;
- unsafe {
- ptr::write_unaligned(dst.byte_add(PAGE_SIZE + offset).cast(), value);
- mmapped_buf.mmap_page.data_head = (offset + mem::size_of::<T>()) as u64;
- mmapped_buf.mmap_page.data_head as usize
- }
- }
-
fn write_sample<T: Debug>(mmapped_buf: &mut MMappedBuf, offset: usize, value: T) -> usize {
- let sample = PerfSample {
- s_hdr: Sample {
- header: perf_event_header {
- type_: PERF_RECORD_SAMPLE as u32,
- misc: 0,
- size: mem::size_of::<PerfSample<T>>() as u16,
+ write(
+ mmapped_buf,
+ offset,
+ PerfSample {
+ s_hdr: Sample {
+ header: perf_event_header {
+ type_: PERF_RECORD_SAMPLE as u32,
+ misc: 0,
+ size: mem::size_of::<PerfSample<T>>() as u16,
+ },
+ size: mem::size_of::<T>() as u32,
},
- size: mem::size_of::<T>() as u32,
+ value,
},
- value,
- };
- write(mmapped_buf, offset, sample)
+ )
}
fn u32_from_buf(buf: &[u8]) -> u32 {
@@ -422,11 +425,12 @@ mod tests {
let mut mmapped_buf = MMappedBuf {
data: [0; PAGE_SIZE * 2],
};
- fake_mmap(&mmapped_buf);
- let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
write_sample(&mut mmapped_buf, 0, 0xCAFEBABEu32);
+ fake_mmap(&mut mmapped_buf);
+ let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
+
let mut out_bufs = [BytesMut::with_capacity(4)];
let events = buf.read_events(&mut out_bufs).unwrap();
@@ -439,12 +443,13 @@ mod tests {
let mut mmapped_buf = MMappedBuf {
data: [0; PAGE_SIZE * 2],
};
- fake_mmap(&mmapped_buf);
- let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
let next = write_sample(&mut mmapped_buf, 0, 0xCAFEBABEu32);
write_sample(&mut mmapped_buf, next, 0xBADCAFEu32);
+ fake_mmap(&mut mmapped_buf);
+ let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
+
let mut out_bufs = [BytesMut::with_capacity(4)];
let events = buf.read_events(&mut out_bufs).unwrap();
@@ -461,12 +466,13 @@ mod tests {
let mut mmapped_buf = MMappedBuf {
data: [0; PAGE_SIZE * 2],
};
- fake_mmap(&mmapped_buf);
- let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
let next = write_sample(&mut mmapped_buf, 0, 0xCAFEBABEu32);
write_sample(&mut mmapped_buf, next, 0xBADCAFEu32);
+ fake_mmap(&mut mmapped_buf);
+ let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
+
let mut out_bufs = (0..3)
.map(|_| BytesMut::with_capacity(4))
.collect::<Vec<_>>();
@@ -482,12 +488,13 @@ mod tests {
let mut mmapped_buf = MMappedBuf {
data: [0; PAGE_SIZE * 2],
};
- fake_mmap(&mmapped_buf);
- let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
let offset = PAGE_SIZE - mem::size_of::<PerfSample<u32>>();
- mmapped_buf.mmap_page.data_tail = offset as u64;
write_sample(&mut mmapped_buf, offset, 0xCAFEBABEu32);
+ mmapped_buf.mmap_page.data_tail = offset as u64;
+
+ fake_mmap(&mut mmapped_buf);
+ let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
let mut out_bufs = [BytesMut::with_capacity(4)];
@@ -501,31 +508,31 @@ mod tests {
let mut mmapped_buf = MMappedBuf {
data: [0; PAGE_SIZE * 2],
};
- fake_mmap(&mmapped_buf);
- let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
-
- let header = perf_event_header {
- type_: PERF_RECORD_SAMPLE as u32,
- misc: 0,
- size: mem::size_of::<PerfSample<u64>>() as u16,
- };
let offset = PAGE_SIZE - mem::size_of::<perf_event_header>() - 2;
+ write(
+ &mut mmapped_buf,
+ offset,
+ perf_event_header {
+ type_: PERF_RECORD_SAMPLE as u32,
+ misc: 0,
+ size: mem::size_of::<PerfSample<u64>>() as u16,
+ },
+ );
mmapped_buf.mmap_page.data_tail = offset as u64;
- write(&mut mmapped_buf, offset, header);
- #[cfg(target_endian = "little")]
- {
- write(&mut mmapped_buf, PAGE_SIZE - 2, 0x0004u16);
- write(&mut mmapped_buf, 0, 0x0000u16);
- }
- #[cfg(target_endian = "big")]
- {
- write(&mut mmapped_buf, PAGE_SIZE - 2, 0x0000u16);
- write(&mut mmapped_buf, 0, 0x0004u16);
- }
+ let (left, right) = if cfg!(target_endian = "little") {
+ (0x0004u16, 0x0000u16)
+ } else {
+ (0x0000u16, 0x0004u16)
+ };
+ write(&mut mmapped_buf, PAGE_SIZE - 2, left);
+ write(&mut mmapped_buf, 0, right);
write(&mut mmapped_buf, 2, 0xBAADCAFEu32);
+ fake_mmap(&mut mmapped_buf);
+ let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
+
let mut out_bufs = [BytesMut::with_capacity(8)];
let events = buf.read_events(&mut out_bufs).unwrap();
@@ -538,31 +545,34 @@ mod tests {
let mut mmapped_buf = MMappedBuf {
data: [0; PAGE_SIZE * 2],
};
- fake_mmap(&mmapped_buf);
- let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
- let sample = PerfSample {
- s_hdr: Sample {
- header: perf_event_header {
- type_: PERF_RECORD_SAMPLE as u32,
- misc: 0,
- size: mem::size_of::<PerfSample<u64>>() as u16,
- },
- size: mem::size_of::<u64>() as u32,
- },
- #[cfg(target_endian = "little")]
- value: 0xCAFEBABEu32,
- #[cfg(target_endian = "big")]
- value: 0xBAADCAFEu32,
+ let (left, right) = if cfg!(target_endian = "little") {
+ (0xCAFEBABEu32, 0xBAADCAFEu32)
+ } else {
+ (0xBAADCAFEu32, 0xCAFEBABEu32)
};
let offset = PAGE_SIZE - mem::size_of::<PerfSample<u32>>();
+ write(
+ &mut mmapped_buf,
+ offset,
+ PerfSample {
+ s_hdr: Sample {
+ header: perf_event_header {
+ type_: PERF_RECORD_SAMPLE as u32,
+ misc: 0,
+ size: mem::size_of::<PerfSample<u64>>() as u16,
+ },
+ size: mem::size_of::<u64>() as u32,
+ },
+ value: left,
+ },
+ );
+ write(&mut mmapped_buf, 0, right);
mmapped_buf.mmap_page.data_tail = offset as u64;
- write(&mut mmapped_buf, offset, sample);
- #[cfg(target_endian = "little")]
- write(&mut mmapped_buf, 0, 0xBAADCAFEu32);
- #[cfg(target_endian = "big")]
- write(&mut mmapped_buf, 0, 0xCAFEBABEu32);
+
+ fake_mmap(&mut mmapped_buf);
+ let mut buf = PerfBuffer::open(1, PAGE_SIZE, 1).unwrap();
let mut out_bufs = [BytesMut::with_capacity(8)];