[PATCHv2 bpf-next 01/24] bpf: Add multi uprobe link

Jiri Olsa
2023-06-20T08:36:04Z

Adding new multi uprobe link that allows to attach bpf program
to multiple uprobes.

Uprobes to attach are specified via new link_create uprobe_multi
union:

struct {
__u32 flags;
__u32 cnt;
__aligned_u64 path;
__aligned_u64 offsets;
__aligned_u64 ref_ctr_offsets;
} uprobe_multi;

Uprobes are defined for single binary specified in path and multiple
calling sites specified in offsets array with optional reference
counters specified in ref_ctr_offsets array. All specified arrays
have length of 'cnt'.

The 'flags' supports single bit for now that marks the uprobe as
return probe.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
include/linux/trace_events.h | 6 +
include/uapi/linux/bpf.h | 14 ++
kernel/bpf/syscall.c | 12 +-
kernel/trace/bpf_trace.c | 237 +++++++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 14 ++
5 files changed, 281 insertions(+), 2 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 0e373222a6df..b0db245fc0f5 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -749,6 +749,7 @@ int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
u32 *fd_type, const char **buf,
u64 *probe_offset, u64 *probe_addr);
int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
+int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
#else
static inline unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
{
@@ -795,6 +796,11 @@ bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
return -EOPNOTSUPP;
}
+static inline int
+bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+ return -EOPNOTSUPP;
+}
#endif

enum {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index a7b5e91dd768..bfbc1246b220 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1035,6 +1035,7 @@ enum bpf_attach_type {
BPF_TRACE_KPROBE_MULTI,
BPF_LSM_CGROUP,
BPF_STRUCT_OPS,
+ BPF_TRACE_UPROBE_MULTI,
__MAX_BPF_ATTACH_TYPE
};

@@ -1052,6 +1053,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_KPROBE_MULTI = 8,
BPF_LINK_TYPE_STRUCT_OPS = 9,
BPF_LINK_TYPE_NETFILTER = 10,
+ BPF_LINK_TYPE_UPROBE_MULTI = 11,

MAX_BPF_LINK_TYPE,
};
@@ -1169,6 +1171,11 @@ enum bpf_link_type {
*/
#define BPF_F_KPROBE_MULTI_RETURN (1U << 0)

+/* link_create.uprobe_multi.flags used in LINK_CREATE command for
+ * BPF_TRACE_UPROBE_MULTI attach type to create return probe.
+ */
+#define BPF_F_UPROBE_MULTI_RETURN (1U << 0)
+
/* When BPF ldimm64's insn[0].src_reg != 0 then this can have
* the following extensions:
*
@@ -1578,6 +1585,13 @@ union bpf_attr {
__s32 priority;
__u32 flags;
} netfilter;
+ struct {
+ __u32 flags;
+ __u32 cnt;
+ __aligned_u64 path;
+ __aligned_u64 offsets;
+ __aligned_u64 ref_ctr_offsets;
+ } uprobe_multi;
};
} link_create;

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index a75c54b6f8a3..a96e46cd407e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3516,6 +3516,11 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
return prog->enforce_expected_attach_type &&
prog->expected_attach_type != attach_type ?
-EINVAL : 0;
+ case BPF_PROG_TYPE_KPROBE:
+ if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI &&
+ attach_type != BPF_TRACE_KPROBE_MULTI)
+ return -EINVAL;
+ fallthrough;
default:
return 0;
}
@@ -4681,7 +4686,8 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)
break;
case BPF_PROG_TYPE_KPROBE:
if (attr->link_create.attach_type != BPF_PERF_EVENT &&
- attr->link_create.attach_type != BPF_TRACE_KPROBE_MULTI) {
+ attr->link_create.attach_type != BPF_TRACE_KPROBE_MULTI &&
+ attr->link_create.attach_type != BPF_TRACE_UPROBE_MULTI) {
ret = -EINVAL;
goto out;
}
@@ -4748,8 +4754,10 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)
case BPF_PROG_TYPE_KPROBE:
if (attr->link_create.attach_type == BPF_PERF_EVENT)
ret = bpf_perf_link_attach(attr, prog);
- else
+ else if (attr->link_create.attach_type == BPF_TRACE_KPROBE_MULTI)
ret = bpf_kprobe_multi_link_attach(attr, prog);
+ else if (attr->link_create.attach_type == BPF_TRACE_UPROBE_MULTI)
+ ret = bpf_uprobe_multi_link_attach(attr, prog);
break;
default:
ret = -EINVAL;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 2bc41e6ac9fe..806ea9fd210d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -23,6 +23,7 @@
#include <linux/sort.h>
#include <linux/key.h>
#include <linux/verification.h>
+#include <linux/namei.h>

#include <net/bpf_sk_storage.h>

@@ -2912,3 +2913,239 @@ static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx)
return 0;
}
#endif
+
+#ifdef CONFIG_UPROBES
+struct bpf_uprobe_multi_link;
+
+struct bpf_uprobe {
+ struct bpf_uprobe_multi_link *link;
+ loff_t offset;
+ struct uprobe_consumer consumer;
+};
+
+struct bpf_uprobe_multi_link {
+ struct path path;
+ struct bpf_link link;
+ u32 cnt;
+ struct bpf_uprobe *uprobes;
+};
+
+struct bpf_uprobe_multi_run_ctx {
+ struct bpf_run_ctx run_ctx;
+ unsigned long entry_ip;
+};
+
+static void bpf_uprobe_unregister(struct path *path, struct bpf_uprobe *uprobes,
+ u32 cnt)
+{
+ u32 i;
+
+ for (i = 0; i < cnt; i++) {
+ uprobe_unregister(d_real_inode(path->dentry), uprobes[i].offset,
+ &uprobes[i].consumer);
+ }
+}
+
+static void bpf_uprobe_multi_link_release(struct bpf_link *link)
+{
+ struct bpf_uprobe_multi_link *umulti_link;
+
+ umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
+ bpf_uprobe_unregister(&umulti_link->path, umulti_link->uprobes, umulti_link->cnt);
+ path_put(&umulti_link->path);
+}
+
+static void bpf_uprobe_multi_link_dealloc(struct bpf_link *link)
+{
+ struct bpf_uprobe_multi_link *umulti_link;
+
+ umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
+ kvfree(umulti_link->uprobes);
+ kfree(umulti_link);
+}
+
+static const struct bpf_link_ops bpf_uprobe_multi_link_lops = {
+ .release = bpf_uprobe_multi_link_release,
+ .dealloc = bpf_uprobe_multi_link_dealloc,
+};
+
+static int uprobe_prog_run(struct bpf_uprobe *uprobe,
+ unsigned long entry_ip,
+ struct pt_regs *regs)
+{
+ struct bpf_uprobe_multi_link *link = uprobe->link;
+ struct bpf_uprobe_multi_run_ctx run_ctx = {
+ .entry_ip = entry_ip,
+ };
+ struct bpf_prog *prog = link->link.prog;
+ struct bpf_run_ctx *old_run_ctx;
+ int err = 0;
+
+ might_fault();
+
+ rcu_read_lock_trace();
+ migrate_disable();
+
+ if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
+ goto out;
+
+ old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
+
+ if (!prog->aux->sleepable)
+ rcu_read_lock();
+
+ err = bpf_prog_run(link->link.prog, regs);
+
+ if (!prog->aux->sleepable)
+ rcu_read_unlock();
+
+ bpf_reset_run_ctx(old_run_ctx);
+
+out:
+ __this_cpu_dec(bpf_prog_active);
+ migrate_enable();
+ rcu_read_unlock_trace();
+ return err;
+}
+
+static int
+uprobe_multi_link_handler(struct uprobe_consumer *con, struct pt_regs *regs)
+{
+ struct bpf_uprobe *uprobe;
+
+ uprobe = container_of(con, struct bpf_uprobe, consumer);
+ return uprobe_prog_run(uprobe, instruction_pointer(regs), regs);
+}
+
+static int
+uprobe_multi_link_ret_handler(struct uprobe_consumer *con, unsigned long func, struct pt_regs *regs)
+{
+ struct bpf_uprobe *uprobe;
+
+ uprobe = container_of(con, struct bpf_uprobe, consumer);
+ return uprobe_prog_run(uprobe, func, regs);
+}
+
+int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+ unsigned long __user *uref_ctr_offsets, ref_ctr_offset = 0;
+ struct bpf_uprobe_multi_link *link = NULL;
+ unsigned long __user *uoffsets, offset;
+ unsigned long *ref_ctr_offsets = NULL;
+ struct bpf_link_primer link_primer;
+ struct bpf_uprobe *uprobes = NULL;
+ void __user *upath;
+ u32 flags, cnt, i;
+ struct path path;
+ char *name;
+ int err;
+
+ /* no support for 32bit archs yet */
+ if (sizeof(u64) != sizeof(void *))
+ return -EOPNOTSUPP;
+
+ if (prog->expected_attach_type != BPF_TRACE_UPROBE_MULTI)
+ return -EINVAL;
+
+ flags = attr->link_create.uprobe_multi.flags;
+ if (flags & ~BPF_F_UPROBE_MULTI_RETURN)
+ return -EINVAL;
+
+ /*
+ * path, offsets and cnt are mandatory,
+ * ref_ctr_offsets is optional
+ */
+ upath = u64_to_user_ptr(attr->link_create.uprobe_multi.path);
+ uoffsets = u64_to_user_ptr(attr->link_create.uprobe_multi.offsets);
+ cnt = attr->link_create.uprobe_multi.cnt;
+ if (!upath || !uoffsets || !cnt)
+ return -EINVAL;
+
+ uref_ctr_offsets = u64_to_user_ptr(attr->link_create.uprobe_multi.ref_ctr_offsets);
+
+ name = strndup_user(upath, PATH_MAX);
+ if (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ return err;
+ }
+
+ err = kern_path(name, LOOKUP_FOLLOW, &path);
+ kfree(name);
+ if (err)
+ return err;
+
+ if (!d_is_reg(path.dentry)) {
+ err = -EINVAL;
+ goto error_path_put;
+ }
+
+ err = -ENOMEM;
+
+ link = kzalloc(sizeof(*link), GFP_KERNEL);
+ uprobes = kvcalloc(cnt, sizeof(*uprobes), GFP_KERNEL);
+ ref_ctr_offsets = kvcalloc(cnt, sizeof(*ref_ctr_offsets), GFP_KERNEL);
+
+ if (!uprobes || !ref_ctr_offsets || !link)
+ goto error_free;
+
+ for (i = 0; i < cnt; i++) {
+ if (uref_ctr_offsets && __get_user(ref_ctr_offset, uref_ctr_offsets + i)) {
+ err = -EFAULT;
+ goto error_free;
+ }
+ if (__get_user(offset, uoffsets + i)) {
+ err = -EFAULT;
+ goto error_free;
+ }
+
+ uprobes[i].offset = offset;
+ uprobes[i].link = link;
+
+ if (flags & BPF_F_UPROBE_MULTI_RETURN)
+ uprobes[i].consumer.ret_handler = uprobe_multi_link_ret_handler;
+ else
+ uprobes[i].consumer.handler = uprobe_multi_link_handler;
+
+ ref_ctr_offsets[i] = ref_ctr_offset;
+ }
+
+ link->cnt = cnt;
+ link->uprobes = uprobes;
+ link->path = path;
+
+ bpf_link_init(&link->link, BPF_LINK_TYPE_UPROBE_MULTI,
+ &bpf_uprobe_multi_link_lops, prog);
+
+ err = bpf_link_prime(&link->link, &link_primer);
+ if (err)
+ goto error_free;
+
+ for (i = 0; i < cnt; i++) {
+ err = uprobe_register_refctr(d_real_inode(link->path.dentry),
+ uprobes[i].offset, ref_ctr_offsets[i],
+ &uprobes[i].consumer);
+ if (err) {
+ bpf_uprobe_unregister(&path, uprobes, i);
+ bpf_link_cleanup(&link_primer);
+ kvfree(ref_ctr_offsets);
+ return err;
+ }
+ }
+
+ kvfree(ref_ctr_offsets);
+ return bpf_link_settle(&link_primer);
+
+error_free:
+ kvfree(ref_ctr_offsets);
+ kvfree(uprobes);
+ kfree(link);
+error_path_put:
+ path_put(&path);
+ return err;
+}
+#else /* !CONFIG_UPROBES */
+int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+ return -EOPNOTSUPP;
+}
+#endif /* CONFIG_UPROBES */
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index a7b5e91dd768..bfbc1246b220 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1035,6 +1035,7 @@ enum bpf_attach_type {
BPF_TRACE_KPROBE_MULTI,
BPF_LSM_CGROUP,
BPF_STRUCT_OPS,
+ BPF_TRACE_UPROBE_MULTI,
__MAX_BPF_ATTACH_TYPE
};

@@ -1052,6 +1053,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_KPROBE_MULTI = 8,
BPF_LINK_TYPE_STRUCT_OPS = 9,
BPF_LINK_TYPE_NETFILTER = 10,
+ BPF_LINK_TYPE_UPROBE_MULTI = 11,

MAX_BPF_LINK_TYPE,
};
@@ -1169,6 +1171,11 @@ enum bpf_link_type {
*/
#define BPF_F_KPROBE_MULTI_RETURN (1U << 0)

+/* link_create.uprobe_multi.flags used in LINK_CREATE command for
+ * BPF_TRACE_UPROBE_MULTI attach type to create return probe.
+ */
+#define BPF_F_UPROBE_MULTI_RETURN (1U << 0)
+
/* When BPF ldimm64's insn[0].src_reg != 0 then this can have
* the following extensions:
*
@@ -1578,6 +1585,13 @@ union bpf_attr {
__s32 priority;
__u32 flags;
} netfilter;
+ struct {
+ __u32 flags;
+ __u32 cnt;
+ __aligned_u64 path;
+ __aligned_u64 offsets;
+ __aligned_u64 ref_ctr_offsets;
+ } uprobe_multi;
};
} link_create;

--
2.41.0