The `bpf_printk!` macro is a helper providing a convenient way to invoke the
`bpf_trace_printk` and `bpf_trace_vprintk` BPF helpers. It is implemented as
a macro because it requires variadic arguments.
Change it from `[i8; 16]` to `[u8; 18]`. `i8` arrays cannot be easily used in
Rust for converting to string (i.e. with `core::str::from_utf8_unchecked`)
and developers have to convert them themselves with unsafe code.
Using u8 arrays lets developers to just convert it with
`core::str::from_utf8_unchecked` without any limitations.
Example:
https://github.com/vadorovsky/aya-examples/blob/main/clone/clone-ebpf/src/main.rs
Signed-off-by: Michal Rostecki <vadorovsky@gmail.com>
This change adds two new helpers:
* bpf_probe_read_user_str_bytes
* bpf_probe_read_kernel_str_bytes
Those new helpers are returning a bytes slice (`&[u8]`) with a length
equal to the length of probed, null-terminated string. When using those
helpers, users don't have to manually check for length and create such
slices themselves. They also make converting to `str` way more
convenient, for example:
```rust
let my_str = unsafe {
core::str::from_utf8_unchecked(
bpf_probe_read_user_str_bytes(user_ptr, &mut buf)?
)
};
```
This change also deprecates the old helpers, since their names are
confusing (they have nothing to do with Rust `str`) and using them
requires writing boilerplate code (for checking the length and making
eBPF verifier happy):
* bpf_probe_read_user_str
* bpf_probe_read_kernel_str
Tested on:
516b29af68
Signed-off-by: Michal Rostecki <vadorovsky@gmail.com>
Before this change, documentation of helper functions (defined by us,
not bindings) were not visible, because `use gen::*` was overriding them
with helpers coming from aya-bpf-bindings, which have the same names and
no docs.
Signed-off-by: Michal Rostecki <vadorovsky@gmail.com>
This helper allows to write to mutable pointers in the userspace, which
come from userspace functions that uprobes attach to.
Signed-off-by: Michal Rostecki <mrostecki@opensuse.org>
This patch adds some documentation to aya-bpf/helpers and adds documentation
for the module itself and for all of the wrappers currently defined in the module.
It also implements the rest of the bpf_probe_read_* wrappers that were missing from this
file. In the future, it probably also makes sense to add some bpf_probe_read_* wrappers
that can read directly into a map pointer, avoiding the BPF stack altogether. I'm going to
call this out of scope for this PR, but plan to submit a subsequent one that addresses
this use case.
Signed-off-by: William Findlay <william@williamfindlay.com>
Until we add another set of bpf_probe_read_* wrappers for reading into a map pointer,
users need access to the underlying bpf_probe_read helper, which is clobbered by this
module. This patch enables direct access to the underlying helpers::gen module to support
such use cases.
In my view, it would also probably make sense to just not export helpers::gen::* and force
the user to opt into helpers::gen, but this can be decided on later.
Signed-off-by: William Findlay <william@williamfindlay.com>
Quentin JEROME
abhijeetbhagat
Joel Höner
Michal Rostecki
tirex
Kenjiro Nakayama
Michal Rostecki
Dan Everton
Alessandro Decina
William Findlay