From 70ed506c3bbcfa846d4636b23051ca79fa4781f7 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 2 Mar 2020 20:31:57 -0800 Subject: bpf: Introduce pinnable bpf_link abstraction Introduce bpf_link abstraction, representing an attachment of BPF program to a BPF hook point (e.g., tracepoint, perf event, etc). bpf_link encapsulates ownership of attached BPF program, reference counting of a link itself, when reference from multiple anonymous inodes, as well as ensures that release callback will be called from a process context, so that users can safely take mutex locks and sleep. Additionally, with a new abstraction it's now possible to generalize pinning of a link object in BPF FS, allowing to explicitly prevent BPF program detachment on process exit by pinning it in a BPF FS and let it open from independent other process to keep working with it. Convert two existing bpf_link-like objects (raw tracepoint and tracing BPF program attachments) into utilizing bpf_link framework, making them pinnable in BPF FS. More FD-based bpf_links will be added in follow up patches. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200303043159.323675-2-andriin@fb.com --- include/linux/bpf.h | 13 +++ kernel/bpf/inode.c | 42 +++++++++- kernel/bpf/syscall.c | 223 +++++++++++++++++++++++++++++++++++++++++---------- 3 files changed, 232 insertions(+), 46 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6015a4daf118..f13c78c6f29d 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1056,6 +1056,19 @@ extern int sysctl_unprivileged_bpf_disabled; int bpf_map_new_fd(struct bpf_map *map, int flags); int bpf_prog_new_fd(struct bpf_prog *prog); +struct bpf_link; + +struct bpf_link_ops { + void (*release)(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_inc(struct bpf_link *link); +void bpf_link_put(struct bpf_link *link); +int bpf_link_new_fd(struct bpf_link *link); +struct bpf_link *bpf_link_get_from_fd(u32 ufd); + int bpf_obj_pin_user(u32 ufd, const char __user *pathname); int bpf_obj_get_user(const char __user *pathname, int flags); diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 5e40e7fccc21..95087d9f4ed3 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -25,6 +25,7 @@ enum bpf_type { BPF_TYPE_UNSPEC = 0, BPF_TYPE_PROG, BPF_TYPE_MAP, + BPF_TYPE_LINK, }; static void *bpf_any_get(void *raw, enum bpf_type type) @@ -36,6 +37,9 @@ static void *bpf_any_get(void *raw, enum bpf_type type) case BPF_TYPE_MAP: bpf_map_inc_with_uref(raw); break; + case BPF_TYPE_LINK: + bpf_link_inc(raw); + break; default: WARN_ON_ONCE(1); break; @@ -53,6 +57,9 @@ static void bpf_any_put(void *raw, enum bpf_type type) case BPF_TYPE_MAP: bpf_map_put_with_uref(raw); break; + case BPF_TYPE_LINK: + bpf_link_put(raw); + break; default: WARN_ON_ONCE(1); break; @@ -63,20 +70,32 @@ static void *bpf_fd_probe_obj(u32 ufd, enum bpf_type *type) { void *raw; - *type = BPF_TYPE_MAP; raw = bpf_map_get_with_uref(ufd); - if (IS_ERR(raw)) { + if (!IS_ERR(raw)) { + *type = BPF_TYPE_MAP; + return raw; + } + + raw = bpf_prog_get(ufd); + if (!IS_ERR(raw)) { *type = BPF_TYPE_PROG; - raw = bpf_prog_get(ufd); + return raw; } - return raw; + raw = bpf_link_get_from_fd(ufd); + if (!IS_ERR(raw)) { + *type = BPF_TYPE_LINK; + return raw; + } + + return ERR_PTR(-EINVAL); } static const struct inode_operations bpf_dir_iops; static const struct inode_operations bpf_prog_iops = { }; static const struct inode_operations bpf_map_iops = { }; +static const struct inode_operations bpf_link_iops = { }; static struct inode *bpf_get_inode(struct super_block *sb, const struct inode *dir, @@ -114,6 +133,8 @@ static int bpf_inode_type(const struct inode *inode, enum bpf_type *type) *type = BPF_TYPE_PROG; else if (inode->i_op == &bpf_map_iops) *type = BPF_TYPE_MAP; + else if (inode->i_op == &bpf_link_iops) + *type = BPF_TYPE_LINK; else return -EACCES; @@ -335,6 +356,12 @@ static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg) &bpffs_map_fops : &bpffs_obj_fops); } +static int bpf_mklink(struct dentry *dentry, umode_t mode, void *arg) +{ + return bpf_mkobj_ops(dentry, mode, arg, &bpf_link_iops, + &bpffs_obj_fops); +} + static struct dentry * bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags) { @@ -411,6 +438,9 @@ static int bpf_obj_do_pin(const char __user *pathname, void *raw, case BPF_TYPE_MAP: ret = vfs_mkobj(dentry, mode, bpf_mkmap, raw); break; + case BPF_TYPE_LINK: + ret = vfs_mkobj(dentry, mode, bpf_mklink, raw); + break; default: ret = -EPERM; } @@ -487,6 +517,8 @@ int bpf_obj_get_user(const char __user *pathname, int flags) ret = bpf_prog_new_fd(raw); else if (type == BPF_TYPE_MAP) ret = bpf_map_new_fd(raw, f_flags); + else if (type == BPF_TYPE_LINK) + ret = bpf_link_new_fd(raw); else return -ENOENT; @@ -504,6 +536,8 @@ static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type if (inode->i_op == &bpf_map_iops) return ERR_PTR(-EINVAL); + if (inode->i_op == &bpf_link_iops) + return ERR_PTR(-EINVAL); if (inode->i_op != &bpf_prog_iops) return ERR_PTR(-EACCES); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index c536c65256ad..13de65363ba2 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2173,24 +2173,154 @@ static int bpf_obj_get(const union bpf_attr *attr) attr->file_flags); } -static int bpf_tracing_prog_release(struct inode *inode, struct file *filp) +struct bpf_link { + atomic64_t refcnt; + const struct bpf_link_ops *ops; + struct bpf_prog *prog; + struct work_struct work; +}; + +void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops, + struct bpf_prog *prog) { - struct bpf_prog *prog = filp->private_data; + atomic64_set(&link->refcnt, 1); + link->ops = ops; + link->prog = prog; +} + +void bpf_link_inc(struct bpf_link *link) +{ + atomic64_inc(&link->refcnt); +} + +/* bpf_link_free is guaranteed to be called from process context */ +static void bpf_link_free(struct bpf_link *link) +{ + struct bpf_prog *prog; - WARN_ON_ONCE(bpf_trampoline_unlink_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); +} + +static void bpf_link_put_deferred(struct work_struct *work) +{ + struct bpf_link *link = container_of(work, struct bpf_link, work); + + bpf_link_free(link); +} + +/* bpf_link_put can be called from atomic context, but ensures that resources + * are freed from process context + */ +void bpf_link_put(struct bpf_link *link) +{ + if (!atomic64_dec_and_test(&link->refcnt)) + return; + + if (in_atomic()) { + INIT_WORK(&link->work, bpf_link_put_deferred); + schedule_work(&link->work); + } else { + bpf_link_free(link); + } +} + +static int bpf_link_release(struct inode *inode, struct file *filp) +{ + struct bpf_link *link = filp->private_data; + + bpf_link_put(link); return 0; } -static const struct file_operations bpf_tracing_prog_fops = { - .release = bpf_tracing_prog_release, +#ifdef CONFIG_PROC_FS +static const struct bpf_link_ops bpf_raw_tp_lops; +static const struct bpf_link_ops bpf_tracing_link_lops; +static const struct bpf_link_ops bpf_xdp_link_lops; + +static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp) +{ + const struct bpf_link *link = filp->private_data; + const struct bpf_prog *prog = link->prog; + char prog_tag[sizeof(prog->tag) * 2 + 1] = { }; + const char *link_type; + + if (link->ops == &bpf_raw_tp_lops) + link_type = "raw_tracepoint"; + else if (link->ops == &bpf_tracing_link_lops) + link_type = "tracing"; + else + link_type = "unknown"; + + bin2hex(prog_tag, prog->tag, sizeof(prog->tag)); + seq_printf(m, + "link_type:\t%s\n" + "prog_tag:\t%s\n" + "prog_id:\t%u\n", + link_type, + prog_tag, + prog->aux->id); +} +#endif + +const struct file_operations bpf_link_fops = { +#ifdef CONFIG_PROC_FS + .show_fdinfo = bpf_link_show_fdinfo, +#endif + .release = bpf_link_release, .read = bpf_dummy_read, .write = bpf_dummy_write, }; +int bpf_link_new_fd(struct bpf_link *link) +{ + return anon_inode_getfd("bpf-link", &bpf_link_fops, link, O_CLOEXEC); +} + +struct bpf_link *bpf_link_get_from_fd(u32 ufd) +{ + struct fd f = fdget(ufd); + struct bpf_link *link; + + if (!f.file) + return ERR_PTR(-EBADF); + if (f.file->f_op != &bpf_link_fops) { + fdput(f); + return ERR_PTR(-EINVAL); + } + + link = f.file->private_data; + bpf_link_inc(link); + fdput(f); + + return link; +} + +struct bpf_tracing_link { + struct bpf_link link; +}; + +static void bpf_tracing_link_release(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, +}; + static int bpf_tracing_prog_attach(struct bpf_prog *prog) { - int tr_fd, err; + struct bpf_tracing_link *link; + int link_fd, err; if (prog->expected_attach_type != BPF_TRACE_FENTRY && prog->expected_attach_type != BPF_TRACE_FEXIT && @@ -2199,58 +2329,61 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog) goto out_put_prog; } + link = kzalloc(sizeof(*link), GFP_USER); + if (!link) { + err = -ENOMEM; + goto out_put_prog; + } + bpf_link_init(&link->link, &bpf_tracing_link_lops, prog); + err = bpf_trampoline_link_prog(prog); if (err) - goto out_put_prog; + goto out_free_link; - tr_fd = anon_inode_getfd("bpf-tracing-prog", &bpf_tracing_prog_fops, - prog, O_CLOEXEC); - if (tr_fd < 0) { + link_fd = bpf_link_new_fd(&link->link); + if (link_fd < 0) { WARN_ON_ONCE(bpf_trampoline_unlink_prog(prog)); - err = tr_fd; - goto out_put_prog; + err = link_fd; + goto out_free_link; } - return tr_fd; + return link_fd; +out_free_link: + kfree(link); out_put_prog: bpf_prog_put(prog); return err; } -struct bpf_raw_tracepoint { +struct bpf_raw_tp_link { + struct bpf_link link; struct bpf_raw_event_map *btp; - struct bpf_prog *prog; }; -static int bpf_raw_tracepoint_release(struct inode *inode, struct file *filp) +static void bpf_raw_tp_link_release(struct bpf_link *link) { - struct bpf_raw_tracepoint *raw_tp = filp->private_data; + struct bpf_raw_tp_link *raw_tp = + container_of(link, struct bpf_raw_tp_link, link); - if (raw_tp->prog) { - bpf_probe_unregister(raw_tp->btp, raw_tp->prog); - bpf_prog_put(raw_tp->prog); - } + bpf_probe_unregister(raw_tp->btp, raw_tp->link.prog); bpf_put_raw_tracepoint(raw_tp->btp); kfree(raw_tp); - return 0; } -static const struct file_operations bpf_raw_tp_fops = { - .release = bpf_raw_tracepoint_release, - .read = bpf_dummy_read, - .write = bpf_dummy_write, +static const struct bpf_link_ops bpf_raw_tp_lops = { + .release = bpf_raw_tp_link_release, }; #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_tracepoint *raw_tp; + struct bpf_raw_tp_link *raw_tp; struct bpf_raw_event_map *btp; struct bpf_prog *prog; const char *tp_name; char buf[128]; - int tp_fd, err; + int link_fd, err; if (CHECK_ATTR(BPF_RAW_TRACEPOINT_OPEN)) return -EINVAL; @@ -2302,21 +2435,20 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr) err = -ENOMEM; goto out_put_btp; } + bpf_link_init(&raw_tp->link, &bpf_raw_tp_lops, prog); raw_tp->btp = btp; - raw_tp->prog = prog; err = bpf_probe_register(raw_tp->btp, prog); if (err) goto out_free_tp; - tp_fd = anon_inode_getfd("bpf-raw-tracepoint", &bpf_raw_tp_fops, raw_tp, - O_CLOEXEC); - if (tp_fd < 0) { + link_fd = bpf_link_new_fd(&raw_tp->link); + if (link_fd < 0) { bpf_probe_unregister(raw_tp->btp, prog); - err = tp_fd; + err = link_fd; goto out_free_tp; } - return tp_fd; + return link_fd; out_free_tp: kfree(raw_tp); @@ -3266,15 +3398,21 @@ static int bpf_task_fd_query(const union bpf_attr *attr, if (err) goto out; - if (file->f_op == &bpf_raw_tp_fops) { - struct bpf_raw_tracepoint *raw_tp = file->private_data; - struct bpf_raw_event_map *btp = raw_tp->btp; + if (file->f_op == &bpf_link_fops) { + struct bpf_link *link = file->private_data; - err = bpf_task_fd_query_copy(attr, uattr, - raw_tp->prog->aux->id, - BPF_FD_TYPE_RAW_TRACEPOINT, - btp->tp->name, 0, 0); - goto put_file; + if (link->ops == &bpf_raw_tp_lops) { + struct bpf_raw_tp_link *raw_tp = + container_of(link, struct bpf_raw_tp_link, link); + struct bpf_raw_event_map *btp = raw_tp->btp; + + err = bpf_task_fd_query_copy(attr, uattr, + raw_tp->link.prog->aux->id, + BPF_FD_TYPE_RAW_TRACEPOINT, + btp->tp->name, 0, 0); + goto put_file; + } + goto out_not_supp; } event = perf_get_event(file); @@ -3294,6 +3432,7 @@ static int bpf_task_fd_query(const union bpf_attr *attr, goto put_file; } +out_not_supp: err = -ENOTSUPP; put_file: fput(file); -- cgit v1.2.3 From c016b68edc7a2adf3db0f11fb649797c1f9216ea Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 2 Mar 2020 20:31:58 -0800 Subject: libbpf: Add bpf_link pinning/unpinning With bpf_link abstraction supported by kernel explicitly, add pinning/unpinning API for links. Also allow to create (open) bpf_link from BPF FS file. This API allows to have an "ephemeral" FD-based BPF links (like raw tracepoint or fexit/freplace attachments) surviving user process exit, by pinning them in a BPF FS, which is an important use case for long-running BPF programs. As part of this, expose underlying FD for bpf_link. While legacy bpf_link's might not have a FD associated with them (which will be expressed as a bpf_link with fd=-1), kernel's abstraction is based around FD-based usage, so match it closely. This, subsequently, allows to have a generic pinning/unpinning API for generalized bpf_link. For some types of bpf_links kernel might not support pinning, in which case bpf_link__pin() will return error. With FD being part of generic bpf_link, also get rid of bpf_link_fd in favor of using vanialla bpf_link. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200303043159.323675-3-andriin@fb.com --- tools/lib/bpf/libbpf.c | 131 +++++++++++++++++++++++++++++++++++++---------- tools/lib/bpf/libbpf.h | 5 ++ tools/lib/bpf/libbpf.map | 5 ++ 3 files changed, 114 insertions(+), 27 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 996162801f7a..f8c4042e5855 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -6931,6 +6931,8 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, struct bpf_link { int (*detach)(struct bpf_link *link); int (*destroy)(struct bpf_link *link); + char *pin_path; /* NULL, if not pinned */ + int fd; /* hook FD, -1 if not applicable */ bool disconnected; }; @@ -6960,26 +6962,109 @@ int bpf_link__destroy(struct bpf_link *link) err = link->detach(link); if (link->destroy) link->destroy(link); + if (link->pin_path) + free(link->pin_path); free(link); return err; } -struct bpf_link_fd { - struct bpf_link link; /* has to be at the top of struct */ - int fd; /* hook FD */ -}; +int bpf_link__fd(const struct bpf_link *link) +{ + return link->fd; +} + +const char *bpf_link__pin_path(const struct bpf_link *link) +{ + return link->pin_path; +} + +static int bpf_link__detach_fd(struct bpf_link *link) +{ + return close(link->fd); +} + +struct bpf_link *bpf_link__open(const char *path) +{ + struct bpf_link *link; + int fd; + + fd = bpf_obj_get(path); + if (fd < 0) { + fd = -errno; + pr_warn("failed to open link at %s: %d\n", path, fd); + return ERR_PTR(fd); + } + + link = calloc(1, sizeof(*link)); + if (!link) { + close(fd); + return ERR_PTR(-ENOMEM); + } + link->detach = &bpf_link__detach_fd; + link->fd = fd; + + link->pin_path = strdup(path); + if (!link->pin_path) { + bpf_link__destroy(link); + return ERR_PTR(-ENOMEM); + } + + return link; +} + +int bpf_link__pin(struct bpf_link *link, const char *path) +{ + int err; + + if (link->pin_path) + return -EBUSY; + err = make_parent_dir(path); + if (err) + return err; + err = check_path(path); + if (err) + return err; + + link->pin_path = strdup(path); + if (!link->pin_path) + return -ENOMEM; + + if (bpf_obj_pin(link->fd, link->pin_path)) { + err = -errno; + zfree(&link->pin_path); + return err; + } + + pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path); + return 0; +} + +int bpf_link__unpin(struct bpf_link *link) +{ + int err; + + if (!link->pin_path) + return -EINVAL; + + err = unlink(link->pin_path); + if (err != 0) + return -errno; + + pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path); + zfree(&link->pin_path); + return 0; +} static int bpf_link__detach_perf_event(struct bpf_link *link) { - struct bpf_link_fd *l = (void *)link; int err; - err = ioctl(l->fd, PERF_EVENT_IOC_DISABLE, 0); + err = ioctl(link->fd, PERF_EVENT_IOC_DISABLE, 0); if (err) err = -errno; - close(l->fd); + close(link->fd); return err; } @@ -6987,7 +7072,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd) { char errmsg[STRERR_BUFSIZE]; - struct bpf_link_fd *link; + struct bpf_link *link; int prog_fd, err; if (pfd < 0) { @@ -7005,7 +7090,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); - link->link.detach = &bpf_link__detach_perf_event; + link->detach = &bpf_link__detach_perf_event; link->fd = pfd; if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) { @@ -7024,7 +7109,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); return ERR_PTR(err); } - return (struct bpf_link *)link; + return link; } /* @@ -7312,18 +7397,11 @@ out: return link; } -static int bpf_link__detach_fd(struct bpf_link *link) -{ - struct bpf_link_fd *l = (void *)link; - - return close(l->fd); -} - struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog, const char *tp_name) { char errmsg[STRERR_BUFSIZE]; - struct bpf_link_fd *link; + struct bpf_link *link; int prog_fd, pfd; prog_fd = bpf_program__fd(prog); @@ -7336,7 +7414,7 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog, link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); - link->link.detach = &bpf_link__detach_fd; + link->detach = &bpf_link__detach_fd; pfd = bpf_raw_tracepoint_open(tp_name, prog_fd); if (pfd < 0) { @@ -7348,7 +7426,7 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog, return ERR_PTR(pfd); } link->fd = pfd; - return (struct bpf_link *)link; + return link; } static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec, @@ -7362,7 +7440,7 @@ static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec, struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog) { char errmsg[STRERR_BUFSIZE]; - struct bpf_link_fd *link; + struct bpf_link *link; int prog_fd, pfd; prog_fd = bpf_program__fd(prog); @@ -7375,7 +7453,7 @@ struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog) link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); - link->link.detach = &bpf_link__detach_fd; + link->detach = &bpf_link__detach_fd; pfd = bpf_raw_tracepoint_open(NULL, prog_fd); if (pfd < 0) { @@ -7409,10 +7487,9 @@ struct bpf_link *bpf_program__attach(struct bpf_program *prog) static int bpf_link__detach_struct_ops(struct bpf_link *link) { - struct bpf_link_fd *l = (void *)link; __u32 zero = 0; - if (bpf_map_delete_elem(l->fd, &zero)) + if (bpf_map_delete_elem(link->fd, &zero)) return -errno; return 0; @@ -7421,7 +7498,7 @@ static int bpf_link__detach_struct_ops(struct bpf_link *link) struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map) { struct bpf_struct_ops *st_ops; - struct bpf_link_fd *link; + struct bpf_link *link; __u32 i, zero = 0; int err; @@ -7453,10 +7530,10 @@ struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map) return ERR_PTR(err); } - link->link.detach = bpf_link__detach_struct_ops; + link->detach = bpf_link__detach_struct_ops; link->fd = map->fd; - return (struct bpf_link *)link; + return link; } enum bpf_perf_event_ret diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 02fc58a21a7f..d38d7a629417 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -219,6 +219,11 @@ LIBBPF_API void bpf_program__unload(struct bpf_program *prog); struct bpf_link; +LIBBPF_API struct bpf_link *bpf_link__open(const char *path); +LIBBPF_API int bpf_link__fd(const struct bpf_link *link); +LIBBPF_API const char *bpf_link__pin_path(const struct bpf_link *link); +LIBBPF_API int bpf_link__pin(struct bpf_link *link, const char *path); +LIBBPF_API int bpf_link__unpin(struct bpf_link *link); LIBBPF_API void bpf_link__disconnect(struct bpf_link *link); LIBBPF_API int bpf_link__destroy(struct bpf_link *link); diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 7b014c8cdece..5129283c0284 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -238,5 +238,10 @@ LIBBPF_0.0.7 { LIBBPF_0.0.8 { global: + bpf_link__fd; + bpf_link__open; + bpf_link__pin; + bpf_link__pin_path; + bpf_link__unpin; bpf_program__set_attach_target; } LIBBPF_0.0.7; -- cgit v1.2.3 From 6489b8e1e3cf0eb8639e96610002837c53a677cd Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 2 Mar 2020 20:31:59 -0800 Subject: selftests/bpf: Add link pinning selftests Add selftests validating link pinning/unpinning and associated BPF link (attachment) lifetime. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200303043159.323675-4-andriin@fb.com --- .../selftests/bpf/prog_tests/link_pinning.c | 105 +++++++++++++++++++++ .../selftests/bpf/progs/test_link_pinning.c | 25 +++++ 2 files changed, 130 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/link_pinning.c create mode 100644 tools/testing/selftests/bpf/progs/test_link_pinning.c diff --git a/tools/testing/selftests/bpf/prog_tests/link_pinning.c b/tools/testing/selftests/bpf/prog_tests/link_pinning.c new file mode 100644 index 000000000000..a743288cf384 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/link_pinning.c @@ -0,0 +1,105 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Facebook */ + +#include +#include + +#include "test_link_pinning.skel.h" + +static int duration = 0; + +void test_link_pinning_subtest(struct bpf_program *prog, + struct test_link_pinning__bss *bss) +{ + const char *link_pin_path = "/sys/fs/bpf/pinned_link_test"; + struct stat statbuf = {}; + struct bpf_link *link; + int err, i; + + link = bpf_program__attach(prog); + if (CHECK(IS_ERR(link), "link_attach", "err: %ld\n", PTR_ERR(link))) + goto cleanup; + + bss->in = 1; + usleep(1); + CHECK(bss->out != 1, "res_check1", "exp %d, got %d\n", 1, bss->out); + + /* pin link */ + err = bpf_link__pin(link, link_pin_path); + if (CHECK(err, "link_pin", "err: %d\n", err)) + goto cleanup; + + CHECK(strcmp(link_pin_path, bpf_link__pin_path(link)), "pin_path1", + "exp %s, got %s\n", link_pin_path, bpf_link__pin_path(link)); + + /* check that link was pinned */ + err = stat(link_pin_path, &statbuf); + if (CHECK(err, "stat_link", "err %d errno %d\n", err, errno)) + goto cleanup; + + bss->in = 2; + usleep(1); + CHECK(bss->out != 2, "res_check2", "exp %d, got %d\n", 2, bss->out); + + /* destroy link, pinned link should keep program attached */ + bpf_link__destroy(link); + link = NULL; + + bss->in = 3; + usleep(1); + CHECK(bss->out != 3, "res_check3", "exp %d, got %d\n", 3, bss->out); + + /* re-open link from BPFFS */ + link = bpf_link__open(link_pin_path); + if (CHECK(IS_ERR(link), "link_open", "err: %ld\n", PTR_ERR(link))) + goto cleanup; + + CHECK(strcmp(link_pin_path, bpf_link__pin_path(link)), "pin_path2", + "exp %s, got %s\n", link_pin_path, bpf_link__pin_path(link)); + + /* unpin link from BPFFS, program still attached */ + err = bpf_link__unpin(link); + if (CHECK(err, "link_unpin", "err: %d\n", err)) + goto cleanup; + + /* still active, as we have FD open now */ + bss->in = 4; + usleep(1); + CHECK(bss->out != 4, "res_check4", "exp %d, got %d\n", 4, bss->out); + + bpf_link__destroy(link); + link = NULL; + + /* Validate it's finally detached. + * Actual detachment might get delayed a bit, so there is no reliable + * way to validate it immediately here, let's count up for long enough + * and see if eventually output stops being updated + */ + for (i = 5; i < 10000; i++) { + bss->in = i; + usleep(1); + if (bss->out == i - 1) + break; + } + CHECK(i == 10000, "link_attached", "got to iteration #%d\n", i); + +cleanup: + if (!IS_ERR(link)) + bpf_link__destroy(link); +} + +void test_link_pinning(void) +{ + struct test_link_pinning* skel; + + skel = test_link_pinning__open_and_load(); + if (CHECK(!skel, "skel_open", "failed to open skeleton\n")) + return; + + if (test__start_subtest("pin_raw_tp")) + test_link_pinning_subtest(skel->progs.raw_tp_prog, skel->bss); + if (test__start_subtest("pin_tp_btf")) + test_link_pinning_subtest(skel->progs.tp_btf_prog, skel->bss); + + test_link_pinning__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_link_pinning.c b/tools/testing/selftests/bpf/progs/test_link_pinning.c new file mode 100644 index 000000000000..bbf2a5264dc0 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_link_pinning.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Facebook */ + +#include +#include +#include + +int in = 0; +int out = 0; + +SEC("raw_tp/sys_enter") +int raw_tp_prog(const void *ctx) +{ + out = in; + return 0; +} + +SEC("tp_btf/sys_enter") +int tp_btf_prog(const void *ctx) +{ + out = in; + return 0; +} + +char _license[] SEC("license") = "GPL"; -- cgit v1.2.3