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Tue, 17 Mar 2026 04:18:52 -0700 (PDT) Received: from localhost ([2a03:2880:10ff:74::]) by smtp.gmail.com with ESMTPSA id 5614622812f47-4673415d291sm11065422b6e.6.2026.03.17.04.18.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 04:18:50 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Eduard Zingerman , Tejun Heo , Dan Schatzberg , kkd@meta.com, kernel-team@meta.com Subject: [PATCH bpf-next v1 0/4] Allow variable offsets for syscall PTR_TO_CTX Date: Tue, 17 Mar 2026 04:18:45 -0700 Message-ID: <20260317111850.2107846-1-memxor@gmail.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1284; h=from:subject; bh=KFlFJ4ciiOxf/VtyvH918HFgXG4tkPSLar79PYdP5L8=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBpuTHi2k7z1x312OB2Y1la0qb+diqD7d/qZZnzhIkK KiWkNtaJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCabkx4gAKCRBM4MiGSL8RyqD3EA CPvv7HWj1tI2rkNw6BoDO4q1Nk6vLvEQSZ//1Lphf1eTR4MkR0le2RtxG9fOYNbL9BwB5hMe5xJuRT 8Hs3JMhUL5xAS455KJ2RzXxBkaR2qxdVmZXq8GnJKHTclg0phyOip7cgW72YOx9DWvmqYBUK3SrcdQ RxLx+7CSU/tH5Nm0QgqtiLmGfOvGTQHpi/jCawZkwLJl/B/DhW8f7+7abT58oogRBjTsIoHgI5ygxB dcJOtGP8SBDH3d7VA372SGRYAEERZfAhDS0mOUCnrvt4cr6GXr+fBCs+xre3K05R5vd0LeCJ8jrslD uXzh1hZF9WjLWs/SVWE8Kn9BmDg+TQeXl4f3gPYnSt9Vqqr678ByyZAmIXEbdh8vWWY72QWjCbSiM1 2KpfAMU0vaoOFPbyLRXT9jxJT6ZtBs7Yeqy6QdPsrKOy3Z3NGI5ErnspfpXMerj5eBIJMOTwYy5RTy cmJVWGyokheJqQI5v+N08v1INwVUA1v02vmiyPgumyQYUBH+9N2eRnSWlZKDpCPZE7ubP5mzBXM8fd RmQdwJq71WuymtC9OPXXRQD/K1VeTYj1mazw/aHtXJ84Vqgi8GhpvtEdeiR8s4ROvIWJpHutNpteY7 XQb+YdCSDQ0Vcnp7YbA7GnfXcrNncGO1K5h7VDPbPAxkqUtOgqVs1eQds35w== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA Content-Transfer-Encoding: 8bit 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. 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 Kumar Kartikeya Dwivedi (4): bpf: Support variable offsets for syscall PTR_TO_CTX selftests/bpf: Adjust syscall ctx variable offset tests bpf: Reject modified syscall PTR_TO_CTX for global subprogs selftests/bpf: Test modified syscall ctx for global subprog kernel/bpf/verifier.c | 62 ++- .../selftests/bpf/prog_tests/verifier.c | 34 +- .../selftests/bpf/progs/verifier_ctx.c | 356 +++++++++++++++--- .../bpf/progs/verifier_global_subprogs.c | 43 ++- .../selftests/bpf/test_kmods/bpf_testmod.c | 2 +- 5 files changed, 409 insertions(+), 88 deletions(-) base-commit: 2364959abecb052d7b798ae51d0626edec8b9288 -- 2.52.0