diff options
| -rw-r--r-- | include/linux/bpf.h | 3 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 122 |
2 files changed, 91 insertions, 34 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 94a329b9da81..4fd91b7c95ea 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1070,13 +1070,16 @@ struct bpf_link; struct bpf_link_ops { void (*release)(struct bpf_link *link); + void (*dealloc)(struct bpf_link *link); }; void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops, struct bpf_prog *prog); +void bpf_link_defunct(struct bpf_link *link); void bpf_link_inc(struct bpf_link *link); void bpf_link_put(struct bpf_link *link); int bpf_link_new_fd(struct bpf_link *link); +struct file *bpf_link_new_file(struct bpf_link *link, int *reserved_fd); struct bpf_link *bpf_link_get_from_fd(u32 ufd); int bpf_obj_pin_user(u32 ufd, const char __user *pathname); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7ce0815793dd..b2f73ecacced 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2188,6 +2188,11 @@ void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops, link->prog = prog; } +void bpf_link_defunct(struct bpf_link *link) +{ + link->prog = NULL; +} + void bpf_link_inc(struct bpf_link *link) { atomic64_inc(&link->refcnt); @@ -2196,14 +2201,13 @@ void bpf_link_inc(struct bpf_link *link) /* bpf_link_free is guaranteed to be called from process context */ static void bpf_link_free(struct bpf_link *link) { - struct bpf_prog *prog; - - /* remember prog locally, because release below will free link memory */ - prog = link->prog; - /* extra clean up and kfree of container link struct */ - link->ops->release(link); - /* no more accesing of link members after this point */ - bpf_prog_put(prog); + if (link->prog) { + /* detach BPF program, clean up used resources */ + link->ops->release(link); + bpf_prog_put(link->prog); + } + /* free bpf_link and its containing memory */ + link->ops->dealloc(link); } static void bpf_link_put_deferred(struct work_struct *work) @@ -2281,6 +2285,33 @@ int bpf_link_new_fd(struct bpf_link *link) return anon_inode_getfd("bpf-link", &bpf_link_fops, link, O_CLOEXEC); } +/* Similar to bpf_link_new_fd, create anon_inode for given bpf_link, but + * instead of immediately installing fd in fdtable, just reserve it and + * return. Caller then need to either install it with fd_install(fd, file) or + * release with put_unused_fd(fd). + * This is useful for cases when bpf_link attachment/detachment are + * complicated and expensive operations and should be delayed until all the fd + * reservation and anon_inode creation succeeds. + */ +struct file *bpf_link_new_file(struct bpf_link *link, int *reserved_fd) +{ + struct file *file; + int fd; + + fd = get_unused_fd_flags(O_CLOEXEC); + if (fd < 0) + return ERR_PTR(fd); + + file = anon_inode_getfile("bpf_link", &bpf_link_fops, link, O_CLOEXEC); + if (IS_ERR(file)) { + put_unused_fd(fd); + return file; + } + + *reserved_fd = fd; + return file; +} + struct bpf_link *bpf_link_get_from_fd(u32 ufd) { struct fd f = fdget(ufd); @@ -2306,20 +2337,26 @@ struct bpf_tracing_link { static void bpf_tracing_link_release(struct bpf_link *link) { + WARN_ON_ONCE(bpf_trampoline_unlink_prog(link->prog)); +} + +static void bpf_tracing_link_dealloc(struct bpf_link *link) +{ struct bpf_tracing_link *tr_link = container_of(link, struct bpf_tracing_link, link); - WARN_ON_ONCE(bpf_trampoline_unlink_prog(link->prog)); kfree(tr_link); } static const struct bpf_link_ops bpf_tracing_link_lops = { .release = bpf_tracing_link_release, + .dealloc = bpf_tracing_link_dealloc, }; static int bpf_tracing_prog_attach(struct bpf_prog *prog) { struct bpf_tracing_link *link; + struct file *link_file; int link_fd, err; if (prog->expected_attach_type != BPF_TRACE_FENTRY && @@ -2337,20 +2374,24 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog) } bpf_link_init(&link->link, &bpf_tracing_link_lops, prog); - err = bpf_trampoline_link_prog(prog); - if (err) - goto out_free_link; + link_file = bpf_link_new_file(&link->link, &link_fd); + if (IS_ERR(link_file)) { + kfree(link); + err = PTR_ERR(link_file); + goto out_put_prog; + } - link_fd = bpf_link_new_fd(&link->link); - if (link_fd < 0) { - WARN_ON_ONCE(bpf_trampoline_unlink_prog(prog)); - err = link_fd; - goto out_free_link; + err = bpf_trampoline_link_prog(prog); + if (err) { + bpf_link_defunct(&link->link); + fput(link_file); + put_unused_fd(link_fd); + goto out_put_prog; } + + fd_install(link_fd, link_file); return link_fd; -out_free_link: - kfree(link); out_put_prog: bpf_prog_put(prog); return err; @@ -2368,19 +2409,28 @@ static void bpf_raw_tp_link_release(struct bpf_link *link) bpf_probe_unregister(raw_tp->btp, raw_tp->link.prog); bpf_put_raw_tracepoint(raw_tp->btp); +} + +static void bpf_raw_tp_link_dealloc(struct bpf_link *link) +{ + struct bpf_raw_tp_link *raw_tp = + container_of(link, struct bpf_raw_tp_link, link); + kfree(raw_tp); } static const struct bpf_link_ops bpf_raw_tp_lops = { .release = bpf_raw_tp_link_release, + .dealloc = bpf_raw_tp_link_dealloc, }; #define BPF_RAW_TRACEPOINT_OPEN_LAST_FIELD raw_tracepoint.prog_fd static int bpf_raw_tracepoint_open(const union bpf_attr *attr) { - struct bpf_raw_tp_link *raw_tp; + struct bpf_raw_tp_link *link; struct bpf_raw_event_map *btp; + struct file *link_file; struct bpf_prog *prog; const char *tp_name; char buf[128]; @@ -2431,28 +2481,32 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr) goto out_put_prog; } - raw_tp = kzalloc(sizeof(*raw_tp), GFP_USER); - if (!raw_tp) { + link = kzalloc(sizeof(*link), GFP_USER); + if (!link) { err = -ENOMEM; goto out_put_btp; } - bpf_link_init(&raw_tp->link, &bpf_raw_tp_lops, prog); - raw_tp->btp = btp; + bpf_link_init(&link->link, &bpf_raw_tp_lops, prog); + link->btp = btp; - err = bpf_probe_register(raw_tp->btp, prog); - if (err) - goto out_free_tp; + link_file = bpf_link_new_file(&link->link, &link_fd); + if (IS_ERR(link_file)) { + kfree(link); + err = PTR_ERR(link_file); + goto out_put_btp; + } - link_fd = bpf_link_new_fd(&raw_tp->link); - if (link_fd < 0) { - bpf_probe_unregister(raw_tp->btp, prog); - err = link_fd; - goto out_free_tp; + err = bpf_probe_register(link->btp, prog); + if (err) { + bpf_link_defunct(&link->link); + fput(link_file); + put_unused_fd(link_fd); + goto out_put_btp; } + + fd_install(link_fd, link_file); return link_fd; -out_free_tp: - kfree(raw_tp); out_put_btp: bpf_put_raw_tracepoint(btp); out_put_prog: |