| Message ID | AM6PR03MB50807D3E0975E184C4D1D0FB99042@AM6PR03MB5080.eurprd03.prod.outlook.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | bpf: Add open-coded style process file iterator and bpf_fget_task() kfunc | expand |
On 12/17/24 3:37 PM, Juntong Deng wrote: > This patch adds the open-coded iterator style process file iterator > kfuncs bpf_iter_task_file_{new,next,destroy} that iterates over all > files opened by the specified process. > > bpf_iter_task_file_next returns a pointer to bpf_iter_task_file_item, > which currently contains *task, *file, fd. This is an extensible > structure that enables compatibility with different versions > through CO-RE. > > 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 <juntong.deng@outlook.com> > --- > kernel/bpf/helpers.c | 3 ++ > kernel/bpf/task_iter.c | 91 ++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 94 insertions(+) > > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c > index cd5f9884d85b..61a652bea0ba 100644 > --- a/kernel/bpf/helpers.c > +++ b/kernel/bpf/helpers.c > @@ -3147,6 +3147,9 @@ 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_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 98d9b4c0daff..149a95762f68 100644 > --- a/kernel/bpf/task_iter.c > +++ b/kernel/bpf/task_iter.c > @@ -1027,6 +1027,97 @@ __bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it) > { > } > > +struct bpf_iter_task_file_item { > + struct task_struct *task; > + struct file *file; > + unsigned int fd; > +} __aligned(8); We probably do not __aligned(8) here as alignment has been guaranteed in struct bpf_iter_task_file_kern. > + > +struct bpf_iter_task_file { > + __u64 __opaque[4]; > +} __aligned(8); > + > +struct bpf_iter_task_file_kern { > + struct bpf_iter_task_file_item item; > + unsigned int next_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; > + struct bpf_iter_task_file_item *item = &kit->item; > + > + 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)); > + > + item->task = get_task_struct(task); > + item->file = NULL; > + item->fd = 0; > + kit->next_fd = 0; > + > + 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 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 bpf_iter_task_file_item > + */ > +__bpf_kfunc struct bpf_iter_task_file_item *bpf_iter_task_file_next(struct bpf_iter_task_file *it) > +{ > + struct bpf_iter_task_file_kern *kit = (void *)it; > + struct bpf_iter_task_file_item *item = &kit->item; > + > + if (item->file) > + fput(item->file); > + > + item->file = fget_task_next(item->task, &kit->next_fd); > + item->fd = kit->next_fd; > + > + kit->next_fd++; > + > + if (!item->file) > + return NULL; Maybe move the above if statement right after iterm->file = fget_task_next(item->task, &kit->next_fd); to make code more coherent? > + > + return item; > +} > + > +/** > + * 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; > + struct bpf_iter_task_file_item *item = &kit->item; > + > + if (item->file) > + fput(item->file); > + > + put_task_struct(item->task); > +} > + > __bpf_kfunc_end_defs(); > > DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index cd5f9884d85b..61a652bea0ba 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -3147,6 +3147,9 @@ 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_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 98d9b4c0daff..149a95762f68 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -1027,6 +1027,97 @@ __bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it) { } +struct bpf_iter_task_file_item { + struct task_struct *task; + struct file *file; + unsigned int fd; +} __aligned(8); + +struct bpf_iter_task_file { + __u64 __opaque[4]; +} __aligned(8); + +struct bpf_iter_task_file_kern { + struct bpf_iter_task_file_item item; + unsigned int next_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; + struct bpf_iter_task_file_item *item = &kit->item; + + 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)); + + item->task = get_task_struct(task); + item->file = NULL; + item->fd = 0; + kit->next_fd = 0; + + 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 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 bpf_iter_task_file_item + */ +__bpf_kfunc struct bpf_iter_task_file_item *bpf_iter_task_file_next(struct bpf_iter_task_file *it) +{ + struct bpf_iter_task_file_kern *kit = (void *)it; + struct bpf_iter_task_file_item *item = &kit->item; + + if (item->file) + fput(item->file); + + item->file = fget_task_next(item->task, &kit->next_fd); + item->fd = kit->next_fd; + + kit->next_fd++; + + if (!item->file) + return NULL; + + return item; +} + +/** + * 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; + struct bpf_iter_task_file_item *item = &kit->item; + + if (item->file) + fput(item->file); + + put_task_struct(item->task); +} + __bpf_kfunc_end_defs(); DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
This patch adds the open-coded iterator style process file iterator kfuncs bpf_iter_task_file_{new,next,destroy} that iterates over all files opened by the specified process. bpf_iter_task_file_next returns a pointer to bpf_iter_task_file_item, which currently contains *task, *file, fd. This is an extensible structure that enables compatibility with different versions through CO-RE. 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 <juntong.deng@outlook.com> --- kernel/bpf/helpers.c | 3 ++ kernel/bpf/task_iter.c | 91 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 94 insertions(+)