From 737d0646a83cdc65c070a9de61a1ef106cca5ff1 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 12 May 2022 15:07:12 -0700 Subject: libbpf: Add safer high-level wrappers for map operations Add high-level API wrappers for most common and typical BPF map operations that works directly on instances of struct bpf_map * (so you don't have to call bpf_map__fd()) and validate key/value size expectations. These helpers require users to specify key (and value, where appropriate) sizes when performing lookup/update/delete/etc. This forces user to actually think and validate (for themselves) those. This is a good thing as user is expected by kernel to implicitly provide correct key/value buffer sizes and kernel will just read/write necessary amount of data. If it so happens that user doesn't set up buffers correctly (which bit people for per-CPU maps especially) kernel either randomly overwrites stack data or return -EFAULT, depending on user's luck and circumstances. These high-level APIs are meant to prevent such unpleasant and hard to debug bugs. This patch also adds bpf_map_delete_elem_flags() low-level API and requires passing flags to bpf_map__delete_elem() API for consistency across all similar APIs, even though currently kernel doesn't expect any extra flags for BPF_MAP_DELETE_ELEM operation. List of map operations that get these high-level APIs: - bpf_map_lookup_elem; - bpf_map_update_elem; - bpf_map_delete_elem; - bpf_map_lookup_and_delete_elem; - bpf_map_get_next_key. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220512220713.2617964-1-andrii@kernel.org --- tools/lib/bpf/bpf.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'tools/lib/bpf/bpf.c') diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c index 5660268e103f..4677644d80f4 100644 --- a/tools/lib/bpf/bpf.c +++ b/tools/lib/bpf/bpf.c @@ -639,6 +639,20 @@ int bpf_map_delete_elem(int fd, const void *key) return libbpf_err_errno(ret); } +int bpf_map_delete_elem_flags(int fd, const void *key, __u64 flags) +{ + union bpf_attr attr; + int ret; + + memset(&attr, 0, sizeof(attr)); + attr.map_fd = fd; + attr.key = ptr_to_u64(key); + attr.flags = flags; + + ret = sys_bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr)); + return libbpf_err_errno(ret); +} + int bpf_map_get_next_key(int fd, const void *key, void *next_key) { union bpf_attr attr; -- cgit v1.2.3