From patchwork Wed Aug 7 23:40:19 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13756859 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B7ECF2B9A1; Wed, 7 Aug 2024 23:40:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723074033; cv=none; b=X9PRCXJEj1zCYWzU3EyY8+qaScZ8wUGxDhqjPrGtLbisKzW8NBDLVlhKMtLPqB9Sw4sw5JirVogw72R4dQY2zFsYbrkUcDNNAchClLVUYxiwt/aSm7fVdRtE9nf5T7TMTV0iyI5qKaAa34qYDPwP66hV7bHm2zWYeYDhL+LK4C8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723074033; c=relaxed/simple; bh=LhsF060tXwoM+zxKKNcrqH5+R35WgWDhOc3Ca3+wrt8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=E0sWTA7PzXzQ5Ohh2IrwpNLZ1xdu9//ckbJClIINW3xkozwsI/5dv+HKpffgOGsYspj57u8Vn+bPLOiGDh5MX7s7Bb2UcylkJh3jmsqLqxs+JmvyhlJLG+BrKngH7nDHixL4eQiSXFfwdln2irOzmOfBjsiJfpW8O3ZVUYWYDzQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZFBTjG4T; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZFBTjG4T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 32805C32781; Wed, 7 Aug 2024 23:40:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723074033; bh=LhsF060tXwoM+zxKKNcrqH5+R35WgWDhOc3Ca3+wrt8=; h=From:To:Cc:Subject:Date:From; b=ZFBTjG4T6PXcNNfxt/LKxPL4ukaBBRA8o6QbsfrnRo3XqpS7mqaQJIjtphHL769WZ i9SrlvEaJGuZLY/QNiQtcB7zKg6noT3I8gGv+hIJeTFYOdvrmh9zb4ektVj/zQMXb9 dIaVIyCgyDkSDJW2sYsn7xtqzbokBZ6oSIOXTfJS3Z3W6iGsqS+1N2XVJ5x0qEU1VT YYVol4l74GBfbQqOsdWK2j9B0J0gmXKrRGEH13TQkTrVwd/wAvtgPHAdx2SXCjNs1O GOG+vVojGkHI3BPpvFdm6FMcPSknFhWvQHDfhEwSqGlCLfjy8AAxJZsrKWdjXqBGkx tgfPb8dLRxg1w== From: Andrii Nakryiko To: bpf@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, adobriyan@gmail.com, shakeel.butt@linux.dev, hannes@cmpxchg.org, ak@linux.intel.com, osandov@osandov.com, song@kernel.org, jannh@google.com, linux-fsdevel@vger.kernel.org, willy@infradead.org, Andrii Nakryiko Subject: [PATCH v4 bpf-next 00/10] Harden and extend ELF build ID parsing logic Date: Wed, 7 Aug 2024 16:40:19 -0700 Message-ID: <20240807234029.456316-1-andrii@kernel.org> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The goal of this patch set is to extend existing ELF build ID parsing logic, currently mostly used by BPF subsystem, with support for working in sleepable mode in which memory faults are allowed and can be relied upon to fetch relevant parts of ELF file to find and fetch .note.gnu.build-id information. This is useful and important for BPF subsystem itself, but also for PROCMAP_QUERY ioctl(), built atop of /proc//maps functionality (see [0]), which makes use of the same build_id_parse() functionality. PROCMAP_QUERY is always called from sleepable user process context, so it doesn't have to suffer from current restrictions of build_id_parse() which are due to the NMI context assumption. Along the way, we harden the logic to avoid TOCTOU, overflow, out-of-bounds access problems. This is the very first patch, which can be backported to older releases, if necessary. We also lift existing limitations of only working as long as ELF program headers and build ID note section is contained strictly within the very first page of ELF file. We achieve all of the above without duplication of logic between sleepable and non-sleepable modes through freader abstraction that manages underlying folio from page cache (on demand) and gives a simple to use direct memory access interface. With that, single page restrictions and adding sleepable mode support is rather straightforward. We also extend existing set of BPF selftests with a few tests targeting build ID logic across sleepable and non-sleepabe contexts (we utilize sleepable and non-sleepable uprobes for that). [0] https://lore.kernel.org/linux-mm/20240627170900.1672542-4-andrii@kernel.org/ v3->v4: - fix few more potential overflow and out-of-bounds access issues (Andi); - use purely folio-based implementation for freader (Matthew); v2->v3: - remove unneeded READ_ONCE()s and force phoff to u64 for 32-bit mode (Andi); - moved hardening fixes to the front for easier backporting (Jann); - call freader_cleanup() from build_id_parse_buf() for consistency (Jiri); v1->v2: - ensure MADV_PAGEOUT works reliably by paging data in first (Shakeel); - to fix BPF CI build optionally define MADV_POPULATE_READ in selftest. Andrii Nakryiko (10): lib/buildid: harden build ID parsing logic lib/buildid: add single folio-based file reader abstraction lib/buildid: take into account e_phoff when fetching program headers lib/buildid: remove single-page limit for PHDR search lib/buildid: rename build_id_parse() into build_id_parse_nofault() lib/buildid: implement sleepable build_id_parse() API lib/buildid: don't limit .note.gnu.build-id to the first page in ELF bpf: decouple stack_map_get_build_id_offset() from perf_callchain_entry bpf: wire up sleepable bpf_get_stack() and bpf_get_task_stack() helpers selftests/bpf: add build ID tests include/linux/bpf.h | 2 + include/linux/buildid.h | 4 +- kernel/bpf/stackmap.c | 131 ++++-- kernel/events/core.c | 2 +- kernel/trace/bpf_trace.c | 5 +- lib/buildid.c | 389 +++++++++++++----- tools/testing/selftests/bpf/Makefile | 5 +- .../selftests/bpf/prog_tests/build_id.c | 118 ++++++ .../selftests/bpf/progs/test_build_id.c | 31 ++ tools/testing/selftests/bpf/uprobe_multi.c | 41 ++ tools/testing/selftests/bpf/uprobe_multi.ld | 11 + 11 files changed, 598 insertions(+), 141 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/build_id.c create mode 100644 tools/testing/selftests/bpf/progs/test_build_id.c create mode 100644 tools/testing/selftests/bpf/uprobe_multi.ld