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authorDavid Vernet <void@manifault.com>2024-04-05 16:30:40 +0200
committerAndrii Nakryiko <andrii@kernel.org>2024-04-05 19:56:09 +0200
commita8e03b6bbb2cc7cf387d1ce335e4ce4c3bdfef9b (patch)
treeb3cc4c808a9367175e898d47b876ed5bddfc0298 /kernel/bpf/helpers.c
parentbpf, docs: Editorial nits in instruction-set.rst (diff)
downloadlinux-a8e03b6bbb2cc7cf387d1ce335e4ce4c3bdfef9b.tar.xz
linux-a8e03b6bbb2cc7cf387d1ce335e4ce4c3bdfef9b.zip
bpf: Allow invoking kfuncs from BPF_PROG_TYPE_SYSCALL progs
Currently, a set of core BPF kfuncs (e.g. bpf_task_*, bpf_cgroup_*, bpf_cpumask_*, etc) cannot be invoked from BPF_PROG_TYPE_SYSCALL programs. The whitelist approach taken for enabling kfuncs makes sense: it not safe to call these kfuncs from every program type. For example, it may not be safe to call bpf_task_acquire() in an fentry to free_task(). BPF_PROG_TYPE_SYSCALL, on the other hand, is a perfectly safe program type from which to invoke these kfuncs, as it's a very controlled environment, and we should never be able to run into any of the typical problems such as recursive invoations, acquiring references on freeing kptrs, etc. Being able to invoke these kfuncs would be useful, as BPF_PROG_TYPE_SYSCALL can be invoked with BPF_PROG_RUN, and would therefore enable user space programs to synchronously call into BPF to manipulate these kptrs. This patch therefore enables invoking the aforementioned core kfuncs from BPF_PROG_TYPE_SYSCALL progs. Signed-off-by: David Vernet <void@manifault.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/bpf/20240405143041.632519-2-void@manifault.com
Diffstat (limited to 'kernel/bpf/helpers.c')
-rw-r--r--kernel/bpf/helpers.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index d9e7aca8ae9e..8cde717137bd 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2653,6 +2653,7 @@ static int __init kfunc_init(void)
ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &generic_kfunc_set);
ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &generic_kfunc_set);
ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &generic_kfunc_set);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &generic_kfunc_set);
ret = ret ?: register_btf_id_dtor_kfuncs(generic_dtors,
ARRAY_SIZE(generic_dtors),
THIS_MODULE);