From patchwork Thu Nov 30 14:01:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 13474427 Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB1DE196 for ; Thu, 30 Nov 2023 06:00:19 -0800 (PST) Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4SgyWL1lJsz4f3lwY for ; Thu, 30 Nov 2023 22:00:14 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 3D6081A085E for ; Thu, 30 Nov 2023 22:00:16 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP1 (Coremail) with SMTP id cCh0CgBXWhBslWhlJ5NxCQ--.49902S4; Thu, 30 Nov 2023 22:00:14 +0800 (CST) From: Hou Tao To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Andrii Nakryiko , Song Liu , Hao Luo , Yonghong Song , Daniel Borkmann , KP Singh , Stanislav Fomichev , Jiri Olsa , John Fastabend , "Paul E . McKenney" , houtao1@huawei.com Subject: [PATCH bpf v4 0/7] bpf: Fix the release of inner map Date: Thu, 30 Nov 2023 22:01:13 +0800 Message-Id: <20231130140120.1736235-1-houtao@huaweicloud.com> X-Mailer: git-send-email 2.29.2 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: cCh0CgBXWhBslWhlJ5NxCQ--.49902S4 X-Coremail-Antispam: 1UD129KBjvJXoWxAry7Zw1rCF1kKw1fKw4rZrb_yoWrAw47pF WrKr45Krs7try2vwsrGw47Wa4rtws5Ga4Ygr13Gr4rA3y5XryfZryIgFW5CF9xur93t34F vw1avas5W34DZFDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkFb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I 0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1l42xK82IY c2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s 026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF 0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0x vE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2 jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07UWE__UUUUU= X-CM-SenderInfo: xkrx3t3r6k3tpzhluzxrxghudrp/ X-Patchwork-Delegate: bpf@iogearbox.net From: Hou Tao Hi, The patchset aims to fix the release of inner map in map array or map htab. The release of inner map is different with normal map. For normal map, the map is released after the bpf program which uses the map is destroyed, because the bpf program tracks the used maps. However bpf program can not track the used inner map because these inner map may be updated or deleted dynamically, and for now the ref-counter of inner map is decreased after the inner map is remove from outer map, so the inner map may be freed before the bpf program, which is accessing the inner map, exits and there will be use-after-free problem as demonstrated by patch #6. The patchset fixes the problem by deferring the release of inner map. The freeing of inner map is deferred according to the sleepable attributes of the bpf programs which own the outer map. Patch #1 fixes the warning when running the newly-added selftest under interpreter mode. Patch #2 adds more parameters to .map_fd_put_ptr() to prepare for the fix. Patch #3 fixes the incorrect value of need_defer when freeing the fd array. Patch #4 fixes the potential use-after-free problem by using call_rcu_tasks_trace() and call_rcu() to wait for one tasks trace RCU GP and one RCU GP unconditionally. Patch #5 optimizes the free of inner map by removing the unnecessary RCU GP waiting. Patch #6 adds a selftest to demonstrate the potential use-after-free problem. Patch #7 updates a selftest to update outer map in syscall bpf program. Please see individual patches for more details. And comments are always welcome. Change Log: v4: * patch #2: don't use "deferred", use "need_defer" uniformly * patch #3: newly-added, fix the incorrect value of need_defer during fd array free. * patch #4: doesn't consider the case in which bpf map is not used by any bpf program and only use sleepable_refcnt to remove unnecessary tasks trace RCU GP (Alexei) * patch #4: remove memory barriers added due to cautiousness (Alexei) v3: https://lore.kernel.org/bpf/20231124113033.503338-1-houtao@huaweicloud.com * multiple variable renamings (Martin) * define BPF_MAP_RCU_GP/BPF_MAP_RCU_TT_GP as bit (Martin) * use call_rcu() and its variants instead of synchronize_rcu() (Martin) * remove unnecessary mask in bpf_map_free_deferred() (Martin) * place atomic_or() and the related smp_mb() together (Martin) * add patch #6 to demonstrate that updating outer map in syscall program is dead-lock free (Alexei) * update comments about the memory barrier in bpf_map_fd_put_ptr() * update commit message for patch #3 and #4 to describe more details v2: https://lore.kernel.org/bpf/20231113123324.3914612-1-houtao@huaweicloud.com * defer the invocation of ops->map_free() instead of bpf_map_put() (Martin) * update selftest to make it being reproducible under JIT mode (Martin) * remove unnecessary preparatory patches v1: https://lore.kernel.org/bpf/20231107140702.1891778-1-houtao@huaweicloud.com Hou Tao (7): bpf: Check rcu_read_lock_trace_held() before calling bpf map helpers bpf: Add map and need_defer parameters to .map_fd_put_ptr() bpf: Set need_defer as false when clearing fd array during map free bpf: Defer the free of inner map when necessary bpf: Optimize the free of inner map selftests/bpf: Add test cases for inner map selftests/bpf: Test outer map update operations in syscall program include/linux/bpf.h | 15 +- kernel/bpf/arraymap.c | 34 +++-- kernel/bpf/core.c | 4 + kernel/bpf/hashtab.c | 6 +- kernel/bpf/helpers.c | 13 +- kernel/bpf/map_in_map.c | 17 ++- kernel/bpf/map_in_map.h | 2 +- kernel/bpf/syscall.c | 40 ++++- kernel/bpf/verifier.c | 4 +- .../selftests/bpf/prog_tests/map_in_map.c | 141 ++++++++++++++++++ .../selftests/bpf/prog_tests/syscall.c | 30 +++- .../selftests/bpf/progs/access_map_in_map.c | 93 ++++++++++++ tools/testing/selftests/bpf/progs/syscall.c | 91 ++++++++++- 13 files changed, 449 insertions(+), 41 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/map_in_map.c create mode 100644 tools/testing/selftests/bpf/progs/access_map_in_map.c