From b733eeade4204423711793595c3c8d78a2fa8b2e Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 9 Aug 2023 10:34:17 +0200 Subject: [PATCH] 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 Reviewed-by: Oleg Nesterov Signed-off-by: Jiri Olsa Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20230809083440.3209381-6-jolsa@kernel.org Signed-off-by: Alexei Starovoitov --- 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 --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index d7f4f50b1e58..8790b3962e4b 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1642,6 +1642,7 @@ union bpf_attr { __aligned_u64 cookies; __u32 cnt; __u32 flags; + __u32 pid; } uprobe_multi; }; } link_create; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ef17cd05262e..10666d17b9e3 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4882,7 +4882,7 @@ err_put: return err; } -#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.flags +#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 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; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index d7f4f50b1e58..8790b3962e4b 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1642,6 +1642,7 @@ union bpf_attr { __aligned_u64 cookies; __u32 cnt; __u32 flags; + __u32 pid; } uprobe_multi; }; } link_create; -- 2.11.0