diff mbox series

[PATCHv3,bpf-next,04/26] bpf: Add pid filter support for uprobe_multi link

Message ID 20230630083344.984305-5-jolsa@kernel.org (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf: Add multi uprobe link | expand

Checks

Context Check Description
netdev/series_format fail Series longer than 15 patches (and no cover letter)
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1736 this patch: 1736
netdev/cc_maintainers warning 6 maintainers not CCed: linux-trace-kernel@vger.kernel.org mhiramat@kernel.org kpsingh@kernel.org martin.lau@linux.dev song@kernel.org rostedt@goodmis.org
netdev/build_clang fail Errors and warnings before: 188 this patch: 189
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1735 this patch: 1735
netdev/checkpatch warning WARNING: line length of 81 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next-VM_Test-1 success Logs for ${{ matrix.test }} on ${{ matrix.arch }} with ${{ matrix.toolchain_full }}
bpf/vmtest-bpf-next-VM_Test-2 success Logs for ShellCheck
bpf/vmtest-bpf-next-VM_Test-3 success Logs for build for aarch64 with gcc
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Commit Message

Jiri Olsa June 30, 2023, 8:33 a.m. UTC 
Adding support to specify pid for uprobe_multi link and the uprobes
are created only for task with given pid value.

Using the consumer.filter filter callback for that, so the task gets
filtered during the uprobe installation.

We still need to check the task during runtime in the uprobe handler,
because the handler could get executed if there's another system
wide consumer on the same uprobe (thanks Oleg for the insight).

Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/uapi/linux/bpf.h       |  1 +
 kernel/bpf/syscall.c           |  2 +-
 kernel/trace/bpf_trace.c       | 33 +++++++++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  1 +
 4 files changed, 36 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4103f395593b..347c5ed6286b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1593,6 +1593,7 @@  union bpf_attr {
 				__aligned_u64	offsets;
 				__aligned_u64	ref_ctr_offsets;
 				__aligned_u64	cookies;
+				__u32		pid;
 			} uprobe_multi;
 		};
 	} link_create;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index affad356c603..c16b9f80099d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4680,7 +4680,7 @@  static int bpf_map_do_batch(const union bpf_attr *attr,
 	return err;
 }
 
-#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.cookies
+#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.pid
 static int link_create(union bpf_attr *attr, bpfptr_t uattr)
 {
 	struct bpf_prog *prog;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 4657df8f884e..4ef51fd0497f 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2955,6 +2955,7 @@  struct bpf_uprobe_multi_link {
 	struct bpf_link link;
 	u32 cnt;
 	struct bpf_uprobe *uprobes;
+	struct task_struct *task;
 };
 
 struct bpf_uprobe_multi_run_ctx {
@@ -2981,6 +2982,8 @@  static void bpf_uprobe_multi_link_release(struct bpf_link *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);
+	if (umulti_link->task)
+		put_task_struct(umulti_link->task);
 }
 
 static void bpf_uprobe_multi_link_dealloc(struct bpf_link *link)
@@ -3011,6 +3014,9 @@  static int uprobe_prog_run(struct bpf_uprobe *uprobe,
 	struct bpf_run_ctx *old_run_ctx;
 	int err = 0;
 
+	if (link->task && current != link->task)
+		return 0;
+
 	might_fault();
 
 	migrate_disable();
@@ -3033,6 +3039,16 @@  static int uprobe_prog_run(struct bpf_uprobe *uprobe,
 	return err;
 }
 
+static bool
+uprobe_multi_link_filter(struct uprobe_consumer *con, enum uprobe_filter_ctx ctx,
+			 struct mm_struct *mm)
+{
+	struct bpf_uprobe *uprobe;
+
+	uprobe = container_of(con, struct bpf_uprobe, consumer);
+	return uprobe->link->task->mm == mm;
+}
+
 static int
 uprobe_multi_link_handler(struct uprobe_consumer *con, struct pt_regs *regs)
 {
@@ -3066,12 +3082,14 @@  int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	unsigned long *ref_ctr_offsets = NULL;
 	struct bpf_link_primer link_primer;
 	struct bpf_uprobe *uprobes = NULL;
+	struct task_struct *task = NULL;
 	unsigned long __user *uoffsets;
 	u64 __user *ucookies;
 	void __user *upath;
 	u32 flags, cnt, i;
 	struct path path;
 	char *name;
+	pid_t pid;
 	int err;
 
 	/* no support for 32bit archs yet */
@@ -3115,6 +3133,15 @@  int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 		goto error_path_put;
 	}
 
+	pid = attr->link_create.uprobe_multi.pid;
+	if (pid) {
+		rcu_read_lock();
+		task = get_pid_task(find_vpid(pid), PIDTYPE_PID);
+		rcu_read_unlock();
+		if (!task)
+			goto error_path_put;
+	}
+
 	err = -ENOMEM;
 
 	link = kzalloc(sizeof(*link), GFP_KERNEL);
@@ -3149,11 +3176,15 @@  int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 			uprobes[i].consumer.ret_handler = uprobe_multi_link_ret_handler;
 		else
 			uprobes[i].consumer.handler = uprobe_multi_link_handler;
+
+		if (pid)
+			uprobes[i].consumer.filter = uprobe_multi_link_filter;
 	}
 
 	link->cnt = cnt;
 	link->uprobes = uprobes;
 	link->path = path;
+	link->task = task;
 
 	bpf_link_init(&link->link, BPF_LINK_TYPE_UPROBE_MULTI,
 		      &bpf_uprobe_multi_link_lops, prog);
@@ -3182,6 +3213,8 @@  int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	kvfree(ref_ctr_offsets);
 	kvfree(uprobes);
 	kfree(link);
+	if (task)
+		put_task_struct(task);
 error_path_put:
 	path_put(&path);
 	return err;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 4103f395593b..347c5ed6286b 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1593,6 +1593,7 @@  union bpf_attr {
 				__aligned_u64	offsets;
 				__aligned_u64	ref_ctr_offsets;
 				__aligned_u64	cookies;
+				__u32		pid;
 			} uprobe_multi;
 		};
 	} link_create;