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AJvYcCXV86mA9g+1Qb3EZ66EXsn+GH97VZkzlSFFoBOXNwWOIlbqVKIbJzefnym1Pilt+8BqdfU=@vger.kernel.org X-Gm-Message-State: AOJu0YyjpbAKwHwPfpQdyPk9xWeiQUXrDBPoieh9BpK8zkHCUrEPyBF9 7zRuDuE8hEUWOw5HI5oXhwcB03QJvmWhjg4gW8qApo6c08eBy+O3MAxduudtKjp02y7w/qqVdA= = X-Google-Smtp-Source: AGHT+IGi/7aTXmyQZ5xDW/bdnyQbVTiKVhfU9+rw9t4S3CgNTD13Tt0NOWPvtx8xXNuCQvdoJx73CMyzmQ== X-Received: from edsf19.prod.google.com ([2002:aa7:d853:0:b0:5d0:36d0:ad4a]) (user=elver job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6512:124a:b0:53d:e568:ac95 with SMTP id 2adb3069b0e04-53df00de101mr1532948e87.25.1732716613445; Wed, 27 Nov 2024 06:10:13 -0800 (PST) Date: Wed, 27 Nov 2024 15:09:36 +0100 In-Reply-To: <20241127140958.1828012-1-elver@google.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241127140958.1828012-1-elver@google.com> X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog Message-ID: <20241127140958.1828012-2-elver@google.com> Subject: [PATCH bpf-next v3 2/2] bpf: Refactor bpf_tracing_func_proto() and remove bpf_get_probe_write_proto() From: Marco Elver To: elver@google.com, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Nikola Grcevski , bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net With bpf_get_probe_write_proto() no longer printing a message, we can avoid it being a special case with its own permission check. Refactor bpf_tracing_func_proto() similar to bpf_base_func_proto() to have a section conditional on bpf_token_capable(CAP_SYS_ADMIN), where the proto for bpf_probe_write_user() is returned. Finally, remove the unnecessary bpf_get_probe_write_proto(). This simplifies the code, and adding additional CAP_SYS_ADMIN-only helpers in future avoids duplicating the same CAP_SYS_ADMIN check. Suggested-by: Andrii Nakryiko Signed-off-by: Marco Elver Acked-by: Jiri Olsa --- v3: * Fix where bpf_base_func_proto() is called - it needs to be last, because we may override protos (as is e.g. done for BPF_FUNC_get_smp_processor_id). v2: * New patch. --- kernel/trace/bpf_trace.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 0ab56af2e298..9b1d1fa4c06c 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -357,14 +357,6 @@ static const struct bpf_func_proto bpf_probe_write_user_proto = { .arg3_type = ARG_CONST_SIZE, }; -static const struct bpf_func_proto *bpf_get_probe_write_proto(void) -{ - if (!capable(CAP_SYS_ADMIN)) - return NULL; - - return &bpf_probe_write_user_proto; -} - #define MAX_TRACE_PRINTK_VARARGS 3 #define BPF_TRACE_PRINTK_SIZE 1024 @@ -1458,9 +1450,6 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_perf_event_read_proto; case BPF_FUNC_get_prandom_u32: return &bpf_get_prandom_u32_proto; - case BPF_FUNC_probe_write_user: - return security_locked_down(LOCKDOWN_BPF_WRITE_USER) < 0 ? - NULL : bpf_get_probe_write_proto(); case BPF_FUNC_probe_read_user: return &bpf_probe_read_user_proto; case BPF_FUNC_probe_read_kernel: @@ -1539,8 +1528,20 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_trace_vprintk: return bpf_get_trace_vprintk_proto(); default: - return bpf_base_func_proto(func_id, prog); + break; } + + if (bpf_token_capable(prog->aux->token, CAP_SYS_ADMIN)) { + switch (func_id) { + case BPF_FUNC_probe_write_user: + return security_locked_down(LOCKDOWN_BPF_WRITE_USER) < 0 ? + NULL : &bpf_probe_write_user_proto; + default: + break; + } + } + + return bpf_base_func_proto(func_id, prog); } static bool is_kprobe_multi(const struct bpf_prog *prog)