@@ -20,6 +20,7 @@
#include <linux/fprobe.h>
#include <linux/bsearch.h>
#include <linux/sort.h>
+#include <linux/xattr.h>
#include <net/bpf_sk_storage.h>
@@ -1181,6 +1182,47 @@ static const struct bpf_func_proto bpf_get_func_arg_cnt_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+ "kfuncs that are used in tracing/LSM BPF programs");
+
+ssize_t bpf_getxattr(struct dentry *dentry, struct inode *inode,
+ const char *name, void *value, int value__sz)
+{
+ return __vfs_getxattr(dentry, inode, name, value, value__sz);
+}
+
+__diag_pop();
+
+BTF_SET_START(bpf_trace_kfunc_ids)
+BTF_ID(func, bpf_getxattr)
+BTF_SET_END(bpf_trace_kfunc_ids)
+
+BTF_SET_START(bpf_trace_sleepable_kfunc_ids)
+BTF_ID(func, bpf_getxattr)
+BTF_SET_END(bpf_trace_sleepable_kfunc_ids)
+
+static const struct btf_kfunc_id_set bpf_trace_kfunc_set = {
+ .owner = THIS_MODULE,
+ .check_set = &bpf_trace_kfunc_ids,
+ .sleepable_set = &bpf_trace_sleepable_kfunc_ids,
+};
+
+static int __init bpf_trace_kfunc_init(void)
+{
+ int ret;
+
+ ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
+ &bpf_trace_kfunc_set);
+ if (!ret)
+ return ret;
+
+ return register_btf_kfunc_id_set(BPF_PROG_TYPE_LSM,
+ &bpf_trace_kfunc_set);
+
+}
+late_initcall(bpf_trace_kfunc_init);
+
static const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
LSMs like SELinux store security state in xattrs. bpf_getxattr enables BPF LSM to implement similar functionality. In combination with bpf_local_storage, xattrs can be used to develop more complex security policies. This kfunc wraps around __vfs_getxattr which can sleep and is, therefore, limited to sleepable programs using the newly added sleepable_set for kfuncs. Signed-off-by: KP Singh <kpsingh@kernel.org> --- kernel/trace/bpf_trace.c | 42 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+)