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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/fs.h>#include <linux/anon_inodes.h>#include <linux/filter.h>#include <linux/bpf.h>#include <linux/rcupdate_trace.h>
struct bpf_iter_target_info { struct list_head list; const struct bpf_iter_reg *reg_info; u32 btf_id; /* cached value */};
struct bpf_iter_link { struct bpf_link link; struct bpf_iter_aux_info aux; struct bpf_iter_target_info *tinfo;};
struct bpf_iter_priv_data { struct bpf_iter_target_info *tinfo; const struct bpf_iter_seq_info *seq_info; struct bpf_prog *prog; u64 session_id; u64 seq_num; bool done_stop; u8 target_private[] __aligned(8);};
static struct list_head targets = LIST_HEAD_INIT(targets);static DEFINE_MUTEX(targets_mutex);
/* protect bpf_iter_link changes */static DEFINE_MUTEX(link_mutex);
/* incremented on every opened seq_file */static atomic64_t session_id;
static int prepare_seq_file(struct file *file, struct bpf_iter_link *link);
static void bpf_iter_inc_seq_num(struct seq_file *seq){ struct bpf_iter_priv_data *iter_priv;
iter_priv = container_of(seq->private, struct bpf_iter_priv_data, target_private); iter_priv->seq_num++;}
static void bpf_iter_dec_seq_num(struct seq_file *seq){ struct bpf_iter_priv_data *iter_priv;
iter_priv = container_of(seq->private, struct bpf_iter_priv_data, target_private); iter_priv->seq_num--;}
static void bpf_iter_done_stop(struct seq_file *seq){ struct bpf_iter_priv_data *iter_priv;
iter_priv = container_of(seq->private, struct bpf_iter_priv_data, target_private); iter_priv->done_stop = true;}
static inline bool bpf_iter_target_support_resched(const struct bpf_iter_target_info *tinfo){ return tinfo->reg_info->feature & BPF_ITER_RESCHED;}
static bool bpf_iter_support_resched(struct seq_file *seq){ struct bpf_iter_priv_data *iter_priv;
iter_priv = container_of(seq->private, struct bpf_iter_priv_data, target_private); return bpf_iter_target_support_resched(iter_priv->tinfo);}
/* maximum visited objects before bailing out */#define MAX_ITER_OBJECTS 1000000
/* bpf_seq_read, a customized and simpler version for bpf iterator. * The following are differences from seq_read(): * . fixed buffer size (PAGE_SIZE << 3) * . assuming NULL ->llseek() * . stop() may call bpf program, handling potential overflow there */static ssize_t bpf_seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos){ struct seq_file *seq = file->private_data; size_t n, offs, copied = 0; int err = 0, num_objs = 0; bool can_resched; void *p;
mutex_lock(&seq->lock);
if (!seq->buf) { seq->size = PAGE_SIZE << 3; seq->buf = kvmalloc(seq->size, GFP_KERNEL); if (!seq->buf) { err = -ENOMEM; goto done; } }
if (seq->count) { n = min(seq->count, size); err = copy_to_user(buf, seq->buf + seq->from, n); if (err) { err = -EFAULT; goto done; } seq->count -= n; seq->from += n; copied = n; goto done; }
seq->from = 0; p = seq->op->start(seq, &seq->index); if (!p) goto stop; if (IS_ERR(p)) { err = PTR_ERR(p); seq->op->stop(seq, p); seq->count = 0; goto done; }
err = seq->op->show(seq, p); if (err > 0) { /* object is skipped, decrease seq_num, so next * valid object can reuse the same seq_num. */ bpf_iter_dec_seq_num(seq); seq->count = 0; } else if (err < 0 || seq_has_overflowed(seq)) { if (!err) err = -E2BIG; seq->op->stop(seq, p); seq->count = 0; goto done; }
can_resched = bpf_iter_support_resched(seq); while (1) { loff_t pos = seq->index;
num_objs++; offs = seq->count; p = seq->op->next(seq, p, &seq->index); if (pos == seq->index) { pr_info_ratelimited("buggy seq_file .next function %ps " "did not updated position index\n", seq->op->next); seq->index++; }
if (IS_ERR_OR_NULL(p)) break;
/* got a valid next object, increase seq_num */ bpf_iter_inc_seq_num(seq);
if (seq->count >= size) break;
if (num_objs >= MAX_ITER_OBJECTS) { if (offs == 0) { err = -EAGAIN; seq->op->stop(seq, p); goto done; } break; }
err = seq->op->show(seq, p); if (err > 0) { bpf_iter_dec_seq_num(seq); seq->count = offs; } else if (err < 0 || seq_has_overflowed(seq)) { seq->count = offs; if (offs == 0) { if (!err) err = -E2BIG; seq->op->stop(seq, p); goto done; } break; }
if (can_resched) cond_resched(); }stop: offs = seq->count; if (IS_ERR(p)) { seq->op->stop(seq, NULL); err = PTR_ERR(p); goto done; } /* bpf program called if !p */ seq->op->stop(seq, p); if (!p) { if (!seq_has_overflowed(seq)) { bpf_iter_done_stop(seq); } else { seq->count = offs; if (offs == 0) { err = -E2BIG; goto done; } } }
n = min(seq->count, size); err = copy_to_user(buf, seq->buf, n); if (err) { err = -EFAULT; goto done; } copied = n; seq->count -= n; seq->from = n;done: if (!copied) copied = err; else *ppos += copied; mutex_unlock(&seq->lock); return copied;}
static const struct bpf_iter_seq_info *__get_seq_info(struct bpf_iter_link *link){ const struct bpf_iter_seq_info *seq_info;
if (link->aux.map) { seq_info = link->aux.map->ops->iter_seq_info; if (seq_info) return seq_info; }
return link->tinfo->reg_info->seq_info;}
static int iter_open(struct inode *inode, struct file *file){ struct bpf_iter_link *link = inode->i_private;
return prepare_seq_file(file, link);}
static int iter_release(struct inode *inode, struct file *file){ struct bpf_iter_priv_data *iter_priv; struct seq_file *seq;
seq = file->private_data; if (!seq) return 0;
iter_priv = container_of(seq->private, struct bpf_iter_priv_data, target_private);
if (iter_priv->seq_info->fini_seq_private) iter_priv->seq_info->fini_seq_private(seq->private);
bpf_prog_put(iter_priv->prog); seq->private = iter_priv;
return seq_release_private(inode, file);}
const struct file_operations bpf_iter_fops = { .open = iter_open, .read = bpf_seq_read, .release = iter_release,};
/* The argument reg_info will be cached in bpf_iter_target_info. * The common practice is to declare target reg_info as * a const static variable and passed as an argument to * bpf_iter_reg_target(). */int bpf_iter_reg_target(const struct bpf_iter_reg *reg_info){ struct bpf_iter_target_info *tinfo;
tinfo = kzalloc_obj(*tinfo); if (!tinfo) return -ENOMEM;
tinfo->reg_info = reg_info; INIT_LIST_HEAD(&tinfo->list);
mutex_lock(&targets_mutex); list_add(&tinfo->list, &targets); mutex_unlock(&targets_mutex);
return 0;}
void bpf_iter_unreg_target(const struct bpf_iter_reg *reg_info){ struct bpf_iter_target_info *tinfo; bool found = false;
mutex_lock(&targets_mutex); list_for_each_entry(tinfo, &targets, list) { if (reg_info == tinfo->reg_info) { list_del(&tinfo->list); kfree(tinfo); found = true; break; } } mutex_unlock(&targets_mutex);
WARN_ON(found == false);}
static void cache_btf_id(struct bpf_iter_target_info *tinfo, struct bpf_prog *prog){ tinfo->btf_id = prog->aux->attach_btf_id;}
int bpf_iter_prog_supported(struct bpf_prog *prog){ const char *attach_fname = prog->aux->attach_func_name; struct bpf_iter_target_info *tinfo = NULL, *iter; u32 prog_btf_id = prog->aux->attach_btf_id; const char *prefix = BPF_ITER_FUNC_PREFIX; int prefix_len = strlen(prefix);
if (strncmp(attach_fname, prefix, prefix_len)) return -EINVAL;
mutex_lock(&targets_mutex); list_for_each_entry(iter, &targets, list) { if (iter->btf_id && iter->btf_id == prog_btf_id) { tinfo = iter; break; } if (!strcmp(attach_fname + prefix_len, iter->reg_info->target)) { cache_btf_id(iter, prog); tinfo = iter; break; } } mutex_unlock(&targets_mutex);
if (!tinfo) return -EINVAL;
return bpf_prog_ctx_arg_info_init(prog, tinfo->reg_info->ctx_arg_info, tinfo->reg_info->ctx_arg_info_size);}
const struct bpf_func_proto *bpf_iter_get_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog){ const struct bpf_iter_target_info *tinfo; const struct bpf_func_proto *fn = NULL;
mutex_lock(&targets_mutex); list_for_each_entry(tinfo, &targets, list) { if (tinfo->btf_id == prog->aux->attach_btf_id) { const struct bpf_iter_reg *reg_info;
reg_info = tinfo->reg_info; if (reg_info->get_func_proto) fn = reg_info->get_func_proto(func_id, prog); break; } } mutex_unlock(&targets_mutex);
return fn;}
static void bpf_iter_link_release(struct bpf_link *link){ struct bpf_iter_link *iter_link = container_of(link, struct bpf_iter_link, link);
if (iter_link->tinfo->reg_info->detach_target) iter_link->tinfo->reg_info->detach_target(&iter_link->aux);}
static void bpf_iter_link_dealloc(struct bpf_link *link){ struct bpf_iter_link *iter_link = container_of(link, struct bpf_iter_link, link);
kfree(iter_link);}
static int bpf_iter_link_replace(struct bpf_link *link, struct bpf_prog *new_prog, struct bpf_prog *old_prog){ int ret = 0;
mutex_lock(&link_mutex); if (old_prog && link->prog != old_prog) { ret = -EPERM; goto out_unlock; }
if (link->prog->type != new_prog->type || link->prog->expected_attach_type != new_prog->expected_attach_type || link->prog->aux->attach_btf_id != new_prog->aux->attach_btf_id) { ret = -EINVAL; goto out_unlock; }
old_prog = xchg(&link->prog, new_prog); bpf_prog_put(old_prog);
out_unlock: mutex_unlock(&link_mutex); return ret;}
static void bpf_iter_link_show_fdinfo(const struct bpf_link *link, struct seq_file *seq){ struct bpf_iter_link *iter_link = container_of(link, struct bpf_iter_link, link); bpf_iter_show_fdinfo_t show_fdinfo;
seq_printf(seq, "target_name:\t%s\n", iter_link->tinfo->reg_info->target);
show_fdinfo = iter_link->tinfo->reg_info->show_fdinfo; if (show_fdinfo) show_fdinfo(&iter_link->aux, seq);}
static int bpf_iter_link_fill_link_info(const struct bpf_link *link, struct bpf_link_info *info){ struct bpf_iter_link *iter_link = container_of(link, struct bpf_iter_link, link); char __user *ubuf = u64_to_user_ptr(info->iter.target_name); bpf_iter_fill_link_info_t fill_link_info; u32 ulen = info->iter.target_name_len; const char *target_name; u32 target_len;
if (!ulen ^ !ubuf) return -EINVAL;
target_name = iter_link->tinfo->reg_info->target; target_len = strlen(target_name); info->iter.target_name_len = target_len + 1;
if (ubuf) { if (ulen >= target_len + 1) { if (copy_to_user(ubuf, target_name, target_len + 1)) return -EFAULT; } else { char zero = '\0';
if (copy_to_user(ubuf, target_name, ulen - 1)) return -EFAULT; if (put_user(zero, ubuf + ulen - 1)) return -EFAULT; return -ENOSPC; } }
fill_link_info = iter_link->tinfo->reg_info->fill_link_info; if (fill_link_info) return fill_link_info(&iter_link->aux, info);
return 0;}
static const struct bpf_link_ops bpf_iter_link_lops = { .release = bpf_iter_link_release, .dealloc = bpf_iter_link_dealloc, .update_prog = bpf_iter_link_replace, .show_fdinfo = bpf_iter_link_show_fdinfo, .fill_link_info = bpf_iter_link_fill_link_info,};
bool bpf_link_is_iter(struct bpf_link *link){ return link->ops == &bpf_iter_link_lops;}
int bpf_iter_link_attach(const union bpf_attr *attr, bpfptr_t uattr, struct bpf_prog *prog){ struct bpf_iter_target_info *tinfo = NULL, *iter; struct bpf_link_primer link_primer; union bpf_iter_link_info linfo; struct bpf_iter_link *link; u32 prog_btf_id, linfo_len; bpfptr_t ulinfo; int err;
if (attr->link_create.target_fd || attr->link_create.flags) return -EINVAL;
memset(&linfo, 0, sizeof(union bpf_iter_link_info));
ulinfo = make_bpfptr(attr->link_create.iter_info, uattr.is_kernel); linfo_len = attr->link_create.iter_info_len; if (bpfptr_is_null(ulinfo) ^ !linfo_len) return -EINVAL;
if (!bpfptr_is_null(ulinfo)) { err = bpf_check_uarg_tail_zero(ulinfo, sizeof(linfo), linfo_len); if (err) return err; linfo_len = min_t(u32, linfo_len, sizeof(linfo)); if (copy_from_bpfptr(&linfo, ulinfo, linfo_len)) return -EFAULT; }
prog_btf_id = prog->aux->attach_btf_id; mutex_lock(&targets_mutex); list_for_each_entry(iter, &targets, list) { if (iter->btf_id == prog_btf_id) { tinfo = iter; break; } } mutex_unlock(&targets_mutex); if (!tinfo) return -ENOENT;
/* Only allow sleepable program for resched-able iterator */ if (prog->sleepable && !bpf_iter_target_support_resched(tinfo)) return -EINVAL;
link = kzalloc_obj(*link, GFP_USER | __GFP_NOWARN); if (!link) return -ENOMEM;
bpf_link_init(&link->link, BPF_LINK_TYPE_ITER, &bpf_iter_link_lops, prog, attr->link_create.attach_type); link->tinfo = tinfo;
err = bpf_link_prime(&link->link, &link_primer); if (err) { kfree(link); return err; }
if (tinfo->reg_info->attach_target) { err = tinfo->reg_info->attach_target(prog, &linfo, &link->aux); if (err) { bpf_link_cleanup(&link_primer); return err; } }
return bpf_link_settle(&link_primer);}
static void init_seq_meta(struct bpf_iter_priv_data *priv_data, struct bpf_iter_target_info *tinfo, const struct bpf_iter_seq_info *seq_info, struct bpf_prog *prog){ priv_data->tinfo = tinfo; priv_data->seq_info = seq_info; priv_data->prog = prog; priv_data->session_id = atomic64_inc_return(&session_id); priv_data->seq_num = 0; priv_data->done_stop = false;}
static int prepare_seq_file(struct file *file, struct bpf_iter_link *link){ const struct bpf_iter_seq_info *seq_info = __get_seq_info(link); struct bpf_iter_priv_data *priv_data; struct bpf_iter_target_info *tinfo; struct bpf_prog *prog; u32 total_priv_dsize; struct seq_file *seq; int err = 0;
mutex_lock(&link_mutex); prog = link->link.prog; bpf_prog_inc(prog); mutex_unlock(&link_mutex);
tinfo = link->tinfo; total_priv_dsize = offsetof(struct bpf_iter_priv_data, target_private) + seq_info->seq_priv_size; priv_data = __seq_open_private(file, seq_info->seq_ops, total_priv_dsize); if (!priv_data) { err = -ENOMEM; goto release_prog; }
if (seq_info->init_seq_private) { err = seq_info->init_seq_private(priv_data->target_private, &link->aux); if (err) goto release_seq_file; }
init_seq_meta(priv_data, tinfo, seq_info, prog); seq = file->private_data; seq->private = priv_data->target_private;
return 0;
release_seq_file: seq_release_private(file->f_inode, file); file->private_data = NULL;release_prog: bpf_prog_put(prog); return err;}
int bpf_iter_new_fd(struct bpf_link *link){ struct bpf_iter_link *iter_link; unsigned int flags; int err;
if (link->ops != &bpf_iter_link_lops) return -EINVAL;
flags = O_RDONLY | O_CLOEXEC;
FD_PREPARE(fdf, flags, anon_inode_getfile("bpf_iter", &bpf_iter_fops, NULL, flags)); if (fdf.err) return fdf.err;
iter_link = container_of(link, struct bpf_iter_link, link); err = prepare_seq_file(fd_prepare_file(fdf), iter_link); if (err) return err; /* Automatic cleanup handles fput */
return fd_publish(fdf);}
struct bpf_prog *bpf_iter_get_info(struct bpf_iter_meta *meta, bool in_stop){ struct bpf_iter_priv_data *iter_priv; struct seq_file *seq; void *seq_priv;
seq = meta->seq; if (seq->file->f_op != &bpf_iter_fops) return NULL;
seq_priv = seq->private; iter_priv = container_of(seq_priv, struct bpf_iter_priv_data, target_private);
if (in_stop && iter_priv->done_stop) return NULL;
meta->session_id = iter_priv->session_id; meta->seq_num = iter_priv->seq_num;
return iter_priv->prog;}
int bpf_iter_run_prog(struct bpf_prog *prog, void *ctx){ struct bpf_run_ctx run_ctx, *old_run_ctx; int ret;
if (prog->sleepable) { rcu_read_lock_trace(); migrate_disable(); might_fault(); old_run_ctx = bpf_set_run_ctx(&run_ctx); ret = bpf_prog_run(prog, ctx); bpf_reset_run_ctx(old_run_ctx); migrate_enable(); rcu_read_unlock_trace(); } else { rcu_read_lock_dont_migrate(); old_run_ctx = bpf_set_run_ctx(&run_ctx); ret = bpf_prog_run(prog, ctx); bpf_reset_run_ctx(old_run_ctx); rcu_read_unlock_migrate(); }
/* bpf program can only return 0 or 1: * 0 : okay * 1 : retry the same object * The bpf_iter_run_prog() return value * will be seq_ops->show() return value. */ return ret == 0 ? 0 : -EAGAIN;}
BPF_CALL_4(bpf_for_each_map_elem, struct bpf_map *, map, void *, callback_fn, void *, callback_ctx, u64, flags){ return map->ops->map_for_each_callback(map, callback_fn, callback_ctx, flags);}
const struct bpf_func_proto bpf_for_each_map_elem_proto = { .func = bpf_for_each_map_elem, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_PTR_TO_FUNC, .arg3_type = ARG_PTR_TO_STACK_OR_NULL, .arg4_type = ARG_ANYTHING,};
BPF_CALL_4(bpf_loop, u32, nr_loops, void *, callback_fn, void *, callback_ctx, u64, flags){ bpf_callback_t callback = (bpf_callback_t)callback_fn; u64 ret; u32 i;
/* Note: these safety checks are also verified when bpf_loop * is inlined, be careful to modify this code in sync. See * function verifier.c:inline_bpf_loop. */ if (flags) return -EINVAL; if (nr_loops > BPF_MAX_LOOPS) return -E2BIG;
for (i = 0; i < nr_loops; i++) { ret = callback((u64)i, (u64)(long)callback_ctx, 0, 0, 0); /* return value: 0 - continue, 1 - stop and return */ if (ret) return i + 1; }
return i;}
const struct bpf_func_proto bpf_loop_proto = { .func = bpf_loop, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_ANYTHING, .arg2_type = ARG_PTR_TO_FUNC, .arg3_type = ARG_PTR_TO_STACK_OR_NULL, .arg4_type = ARG_ANYTHING,};
struct bpf_iter_num_kern { int cur; /* current value, inclusive */ int end; /* final value, exclusive */} __aligned(8);
__bpf_kfunc_start_defs();
__bpf_kfunc int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end){ struct bpf_iter_num_kern *s = (void *)it;
BUILD_BUG_ON(sizeof(struct bpf_iter_num_kern) != sizeof(struct bpf_iter_num)); BUILD_BUG_ON(__alignof__(struct bpf_iter_num_kern) != __alignof__(struct bpf_iter_num));
/* start == end is legit, it's an empty range and we'll just get NULL * on first (and any subsequent) bpf_iter_num_next() call */ if (start > end) { s->cur = s->end = 0; return -EINVAL; }
/* avoid overflows, e.g., if start == INT_MIN and end == INT_MAX */ if ((s64)end - (s64)start > BPF_MAX_LOOPS) { s->cur = s->end = 0; return -E2BIG; }
/* user will call bpf_iter_num_next() first, * which will set s->cur to exactly start value; * underflow shouldn't matter */ s->cur = start - 1; s->end = end;
return 0;}
__bpf_kfunc int *bpf_iter_num_next(struct bpf_iter_num* it){ struct bpf_iter_num_kern *s = (void *)it;
/* check failed initialization or if we are done (same behavior); * need to be careful about overflow, so convert to s64 for checks, * e.g., if s->cur == s->end == INT_MAX, we can't just do * s->cur + 1 >= s->end */ if ((s64)(s->cur + 1) >= s->end) { s->cur = s->end = 0; return NULL; }
s->cur++;
return &s->cur;}
__bpf_kfunc void bpf_iter_num_destroy(struct bpf_iter_num *it){ struct bpf_iter_num_kern *s = (void *)it;
s->cur = s->end = 0;}
__bpf_kfunc_end_defs();