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authorJiri Olsa <jolsa@kernel.org>2023-08-09 10:34:17 +0200
committerAlexei Starovoitov <ast@kernel.org>2023-08-21 15:51:25 -0700
commitb733eeade4204423711793595c3c8d78a2fa8b2e (patch)
treea3bcec5145f10a15ebfca117823318529167f6f8 /kernel/trace
parent0b779b61f651851df5c5c42938a6c441eb1b5100 (diff)
bpf: Add pid filter support for uprobe_multi link
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> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20230809083440.3209381-6-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/bpf_trace.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 0d59cac30c7e..e45aebed62f5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3003,6 +3003,7 @@ 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 {
@@ -3035,6 +3036,8 @@ 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);
+ if (umulti_link->task)
+ put_task_struct(umulti_link->task);
path_put(&umulti_link->path);
kvfree(umulti_link->uprobes);
kfree(umulti_link);
@@ -3059,6 +3062,9 @@ 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;
+
if (sleepable)
rcu_read_lock_trace();
else
@@ -3079,6 +3085,16 @@ 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)
{
@@ -3112,12 +3128,14 @@ 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 */
@@ -3161,6 +3179,15 @@ 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);
@@ -3195,11 +3222,15 @@ 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);
@@ -3226,6 +3257,8 @@ error_free:
kvfree(ref_ctr_offsets);
kvfree(uprobes);
kfree(link);
+ if (task)
+ put_task_struct(task);
error_path_put:
path_put(&path);
return err;