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Subject[PATCH bpf-next v2 1/3] bpf: add destructive kfunc flag
Date
Add KF_DESTRUCTIVE flag for destructive functions. Functions with this
flag set will require CAP_SYS_BOOT capabilities.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
---
include/linux/btf.h | 1 +
kernel/bpf/verifier.c | 5 +++++
2 files changed, 6 insertions(+)

diff --git a/include/linux/btf.h b/include/linux/btf.h
index cdb376d53238..51a0961c84e3 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -49,6 +49,7 @@
* for this case.
*/
#define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */
+#define KF_DESTRUCTIVE (1 << 5) /* kfunc performs destructive actions */

struct btf;
struct btf_member;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 096fdac70165..e52ca1631d3f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7584,6 +7584,11 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
func_name);
return -EACCES;
}
+ if (*kfunc_flags & KF_DESTRUCTIVE && !capable(CAP_SYS_BOOT)) {
+ verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capabilities\n");
+ return -EACCES;
+ }
+
acq = *kfunc_flags & KF_ACQUIRE;

/* Check the arguments */
--
2.35.3
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