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Tue, 17 Mar 2026 04:19:02 -0700 (PDT) Received: from localhost ([2a03:2880:10ff:74::]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-67bc91174fbsm10954607eaf.4.2026.03.17.04.19.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2026 04:19:00 -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 4/4] selftests/bpf: Test modified syscall ctx for global subprog Date: Tue, 17 Mar 2026 04:18:49 -0700 Message-ID: <20260317111850.2107846-5-memxor@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260317111850.2107846-1-memxor@gmail.com> References: <20260317111850.2107846-1-memxor@gmail.com> 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=1913; h=from:subject; bh=xMU+jRWr1qQYwGaXBcSqzxc6rNeNL978Dgd8RrkBUu8=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBpuTHjoFrAySbjqZ6cgfv+p0aa9gORoNyuxA0+NiFs Q6OjwJuJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCabkx4wAKCRBM4MiGSL8RylfzD/ 4qLPrej350aB21DPGHcws0VAB8K7D9xJz2NFDQUpvhmYbffTG7jF0lDYCiUAq9MF/jFSgOSY37v2B3 FnzV5yDwju4WefZJJ9lLvMsNaV5ak1NKwO0B/rzbSqxFBi8V1GCdYJUjjZIYlXYrwdcNdb0Rzlb6FW oWqfNsHApx12o4V9Mw5HD2iJTJT3M+XVM0/fIfnAMZSpu5qZctkLW7E0k/DdSd1Sf/+Zq8WPORowy/ LmNzjfohCr7vvdgY2GKH49qQxoDiskfY3y0uA6EATCVGKA3v/wglkkA2fdDvfTJwa70IXds2Z0ERdi 8oT6SYwEsqSR1t6pBSWT9NbdL93Pe0PeAdYvHOuBckZecL8lJGmbnbPA74/T26u2BQR4i5SwuXJHTg o32TQqLibmVkHacJS0jLG5l93CMuS5u2JY0hi9xZ3f10FqEjJbJ3yFB+UYiv7xK2UjLGp/NbBIXxxu fNbgFc80JyV69zYOvVGvtt5UvQx68ppQ9BPKELzEVz6/gToiMyX8WIrR1YPx8PI6MVAXLhRlAJD13I y2dBuJB/Zq5UFX8FzzaPuJw56oZLKj9VhFAxgnwogr5dOFx1cob6CVgHg3gztGE3gs70F96fFqJqUR aM86wnDny5SUcn4L5s/D+s6td/m+S7vIgkc4AGDjJtVv5dMQpOxM1tCWAuEA== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA Content-Transfer-Encoding: 8bit Ensure that global subprogs can only accept an unmodified PTR_TO_CTX for syscall programs. For all other program types, fixed or variable offsets on PTR_TO_CTX is rejected when passed into an argument of any call instruction type, through the unified logic of check_func_arg_reg_off. Finally, add a positive example of a case that should succeed with all our previous changes. Signed-off-by: Kumar Kartikeya Dwivedi --- .../bpf/progs/verifier_global_subprogs.c | 42 +++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_global_subprogs.c b/tools/testing/selftests/bpf/progs/verifier_global_subprogs.c index 2250fc31574d..0c14adaddb90 100644 --- a/tools/testing/selftests/bpf/progs/verifier_global_subprogs.c +++ b/tools/testing/selftests/bpf/progs/verifier_global_subprogs.c @@ -357,6 +357,48 @@ int arg_tag_ctx_syscall(void *ctx) return tracing_subprog_void(ctx) + tracing_subprog_u64(ctx) + tp_whatever(ctx); } +__weak int syscall_array_bpf_for(void *ctx __arg_ctx) +{ + int *arr = ctx; + int i; + + bpf_for(i, 0, 100) + arr[i] *= i; + + return 0; +} + +SEC("?syscall") +__success __log_level(2) +int arg_tag_ctx_syscall_bpf_for(void *ctx) +{ + return syscall_array_bpf_for(ctx); +} + +SEC("?syscall") +__failure __log_level(2) +__msg("arg#0 of syscall prog must have zero offset") +int arg_tag_ctx_syscall_fixed_off_bad(void *ctx) +{ + char *p = ctx; + + p += 8; + return subprog_ctx_tag(p); +} + +SEC("?syscall") +__failure __log_level(2) +__msg("arg#0 of syscall prog must have zero offset") +int arg_tag_ctx_syscall_var_off_bad(void *ctx) +{ + __u64 off = bpf_get_prandom_u32(); + char *p = ctx; + + off &= 4; + p += off; + return subprog_ctx_tag(p); +} + __weak int subprog_dynptr(struct bpf_dynptr *dptr) { long *d, t, buf[1] = {}; -- 2.52.0