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42e33c9af4
Kumar Kartikeya Dwivedi says:
====================
Allow variable offsets for syscall PTR_TO_CTX
Enable pointer modification with variable offsets accumulated in the
register for PTR_TO_CTX for syscall programs where it won't be
rewritten, and the context is user-supplied and checked against the max
offset. See patches for details. Fixed offset support landed in [0].
By combining this set with [0], examples like the one below should
succeed verification now.
SEC("syscall")
int prog(void *ctx) {
int *arr = ctx;
int i;
bpf_for(i, 0, 100)
arr[i] *= i;
return 0;
}
[0]: https://lore.kernel.org/bpf/20260227005725.1247305-1-memxor@gmail.com
Changelog:
----------
v4 -> v5
v4: https://lore.kernel.org/bpf/20260401122818.2240807-1-memxor@gmail.com
* Use is_var_ctx_off_allowed() consistently.
* Add acks. (Emil)
v3 -> v4
v3: https://lore.kernel.org/bpf/20260318103526.2590079-1-memxor@gmail.com
* Drop comment around describing choice of fixed or variable offsets. (Eduard)
* Simplify offset adjustment for different cases. (Eduard)
* Add PTR_TO_CTX case in __check_mem_access(). (Eduard)
* Drop aligned access constraint from syscall_prog_is_valid_access().
* Wrap naked checks for BPF_PROG_TYPE_SYSCALL in a utility function. (Eduard)
* Split tests into separate clean up and addition patches. (Eduard)
* Remove CAP_SYS_ADMIN changes. (Eduard)
* Enable unaligned access to syscall ctx, add tests.
* Add more tests for various corner cases.
* Add acks. (Puranjay, Mykyta)
v2 -> v3
v2: https://lore.kernel.org/bpf/20260318075133.1031781-1-memxor@gmail.com
* Prevent arg_type for KF_ARG_PTR_TO_CTX from applying to other cases
due to preceding fallthrough. (Gemini/Sashiko)
v1 -> v2
v1: https://lore.kernel.org/bpf/20260317111850.2107846-2-memxor@gmail.com
* Harden check_func_arg_reg_off check with ARG_PTR_TO_CTX.
* Add tests for unmodified ctx into tail calls.
* Squash unmodified ctx change into base commit.
* Add Reviewed-by's from Emil.
====================
Link: https://patch.msgid.link/20260406194403.1649608-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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