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bpf: Add bpf_copy_from_user_task() helper

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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>
This commit is contained in:
Kenny Yu 2022-01-24 10:54:01 -08:00 committed by Andrii Nakryiko
parent fb0b8a7cea
commit a9491bb920
1 changed files with 11 additions and 0 deletions
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11
include/uapi/linux/bpf.h
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@ -5076,6 +5076,16 @@ union bpf_attr {
* associated to *xdp_md*, at *offset*.
* Return
* 0 on success, or a negative error in case of failure.
*
* long bpf_copy_from_user_task(void *dst, u32 size, const void *user_ptr, struct task_struct *tsk, u64 flags)
* Description
* Read *size* bytes from user space address *user_ptr* in *tsk*'s
* address space, and stores the data in *dst*. *flags* is not
* used yet and is provided for future extensibility. This helper
* can only be used by sleepable programs.
* Return
* 0 on success, or a negative error in case of failure. On error
* *dst* buffer is zeroed out.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -5269,6 +5279,7 @@ union bpf_attr {
FN(xdp_get_buff_len), \
FN(xdp_load_bytes), \
FN(xdp_store_bytes), \
FN(copy_from_user_task), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper