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Wed, 6 Nov 2024 19:39:28 +0000 From: Juntong Deng To: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, memxor@gmail.com, snorcht@gmail.com, brauner@kernel.org Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH bpf-next v3 1/4] bpf/crib: Introduce task_file open-coded iterator kfuncs Date: Wed, 6 Nov 2024 19:38:45 +0000 Message-ID: X-Mailer: git-send-email 2.39.5 In-Reply-To: References: X-ClientProxiedBy: LO4P265CA0280.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:37a::17) To AM6PR03MB5848.eurprd03.prod.outlook.com (2603:10a6:20b:e4::10) X-Microsoft-Original-Message-ID: <20241106193848.160447-1-juntong.deng@outlook.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: AM6PR03MB5848:EE_|AS2PR03MB9792:EE_ X-MS-Office365-Filtering-Correlation-Id: cb6fa12a-530c-48c8-2e90-08dcfe9aba1a X-Microsoft-Antispam: BCL:0;ARA:14566002|461199028|15080799006|19110799003|5072599009|8060799006|3412199025|440099028; 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In addition, this patch adds bpf_iter_task_file_get_fd() getter to get the file descriptor corresponding to the file in the current iteration. The reference to struct file acquired by the previous bpf_iter_task_file_next() is released in the next bpf_iter_task_file_next(), and the last reference is released in the last bpf_iter_task_file_next() that returns NULL. In the bpf_iter_task_file_destroy(), if the iterator does not iterate to the end, then the last struct file reference is released at this time. Signed-off-by: Juntong Deng --- kernel/bpf/helpers.c | 4 ++ kernel/bpf/task_iter.c | 96 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 100 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 395221e53832..1f0f7ca1c47a 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -3096,6 +3096,10 @@ BTF_ID_FLAGS(func, bpf_iter_css_destroy, KF_ITER_DESTROY) BTF_ID_FLAGS(func, bpf_iter_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS | KF_RCU_PROTECTED) BTF_ID_FLAGS(func, bpf_iter_task_next, KF_ITER_NEXT | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_iter_task_destroy, KF_ITER_DESTROY) +BTF_ID_FLAGS(func, bpf_iter_task_file_new, KF_ITER_NEW | KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_iter_task_file_next, KF_ITER_NEXT | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_iter_task_file_get_fd) +BTF_ID_FLAGS(func, bpf_iter_task_file_destroy, KF_ITER_DESTROY) BTF_ID_FLAGS(func, bpf_dynptr_adjust) BTF_ID_FLAGS(func, bpf_dynptr_is_null) BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly) diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index 5af9e130e500..32e15403a5a6 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -1031,6 +1031,102 @@ __bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it) { } +struct bpf_iter_task_file { + __u64 __opaque[3]; +} __aligned(8); + +struct bpf_iter_task_file_kern { + struct task_struct *task; + struct file *file; + int fd; +} __aligned(8); + +/** + * bpf_iter_task_file_new() - Initialize a new task file iterator for a task, + * used to iterate over all files opened by a specified task + * + * @it: the new bpf_iter_task_file to be created + * @task: a pointer pointing to a task to be iterated over + */ +__bpf_kfunc int bpf_iter_task_file_new(struct bpf_iter_task_file *it, + struct task_struct *task) +{ + struct bpf_iter_task_file_kern *kit = (void *)it; + + BUILD_BUG_ON(sizeof(struct bpf_iter_task_file_kern) > sizeof(struct bpf_iter_task_file)); + BUILD_BUG_ON(__alignof__(struct bpf_iter_task_file_kern) != + __alignof__(struct bpf_iter_task_file)); + + kit->task = task; + kit->fd = -1; + kit->file = NULL; + + return 0; +} + +/** + * bpf_iter_task_file_next() - Get the next file in bpf_iter_task_file + * + * bpf_iter_task_file_next acquires a reference to the returned struct file. + * + * The reference to struct file acquired by the previous + * bpf_iter_task_file_next() is released in the next bpf_iter_task_file_next(), + * and the last reference is released in the last bpf_iter_task_file_next() + * that returns NULL. + * + * @it: the bpf_iter_task_file to be checked + * + * @returns a pointer to the struct file of the next file if further files + * are available, otherwise returns NULL + */ +__bpf_kfunc struct file *bpf_iter_task_file_next(struct bpf_iter_task_file *it) +{ + struct bpf_iter_task_file_kern *kit = (void *)it; + + if (kit->file) + fput(kit->file); + + kit->fd++; + + rcu_read_lock(); + kit->file = task_lookup_next_fdget_rcu(kit->task, &kit->fd); + rcu_read_unlock(); + + return kit->file; +} + +/** + * bpf_iter_task_file_get_fd() - Get the file descriptor corresponding to + * the file in the current iteration + * + * @it: the bpf_iter_task_file to be checked + * + * @returns the file descriptor. If -1 is returned, it means the iteration + * has not started yet. + */ +__bpf_kfunc int bpf_iter_task_file_get_fd(struct bpf_iter_task_file *it__iter) +{ + struct bpf_iter_task_file_kern *kit = (void *)it__iter; + + return kit->fd; +} + +/** + * bpf_iter_task_file_destroy() - Destroy a bpf_iter_task_file + * + * If the iterator does not iterate to the end, then the last + * struct file reference is released at this time. + * + * @it: the bpf_iter_task_file to be destroyed + */ +__bpf_kfunc void bpf_iter_task_file_destroy(struct bpf_iter_task_file *it) +{ + struct bpf_iter_task_file_kern *kit = (void *)it; + + if (kit->file) + fput(kit->file); +} + __bpf_kfunc_end_defs(); DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);