diff options
| author | Kenny Yu <kennyyu@fb.com> | 2022-01-24 19:54:01 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-01-25 04:59:27 +0100 |
| commit | 376040e47334c6dc6a939a32197acceb00fe4acf (patch) | |
| tree | 19b75a8c70bc27d8569ebdaf18079494a525bd82 /kernel/bpf/helpers.c | |
| parent | bpf: Add support for bpf iterator programs to use sleepable helpers (diff) | |
| download | linux-376040e47334c6dc6a939a32197acceb00fe4acf.tar.xz linux-376040e47334c6dc6a939a32197acceb00fe4acf.zip | |
bpf: Add bpf_copy_from_user_task() helper
This adds a helper for bpf programs to read the memory of other
tasks.
As an example use case at Meta, we are using a bpf task iterator program
and this new helper to print C++ async stack traces for all threads of
a given process.
Signed-off-by: Kenny Yu <kennyyu@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220124185403.468466-3-kennyyu@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/helpers.c')
| -rw-r--r-- | kernel/bpf/helpers.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 01cfdf40c838..ed2780b76cc1 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -16,6 +16,7 @@ #include <linux/pid_namespace.h> #include <linux/proc_ns.h> #include <linux/security.h> +#include <linux/btf_ids.h> #include "../../lib/kstrtox.h" @@ -671,6 +672,39 @@ const struct bpf_func_proto bpf_copy_from_user_proto = { .arg3_type = ARG_ANYTHING, }; +BPF_CALL_5(bpf_copy_from_user_task, void *, dst, u32, size, + const void __user *, user_ptr, struct task_struct *, tsk, u64, flags) +{ + int ret; + + /* flags is not used yet */ + if (unlikely(flags)) + return -EINVAL; + + if (unlikely(!size)) + return 0; + + ret = access_process_vm(tsk, (unsigned long)user_ptr, dst, size, 0); + if (ret == size) + return 0; + + memset(dst, 0, size); + /* Return -EFAULT for partial read */ + return ret < 0 ? ret : -EFAULT; +} + +const struct bpf_func_proto bpf_copy_from_user_task_proto = { + .func = bpf_copy_from_user_task, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_UNINIT_MEM, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, + .arg3_type = ARG_ANYTHING, + .arg4_type = ARG_PTR_TO_BTF_ID, + .arg4_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK], + .arg5_type = ARG_ANYTHING +}; + BPF_CALL_2(bpf_per_cpu_ptr, const void *, ptr, u32, cpu) { if (cpu >= nr_cpu_ids) |