Merge branch 'more-gen_loader-fixes-2'

Daniel Borkmann says:

====================
More gen_loader fixes #2

Another small follow-up from the sashiko findings about signed loaders.
In particular, closing the gap to reject exclusive maps in iterators.
====================

Link: https://patch.msgid.link/20260602133052.423725-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: Alexei Starovoitov

kernel/bpf/map_iter.c

@@ -112,6 +112,10 @@ static int bpf_iter_attach_map(struct bpf_prog *prog,
 	map = bpf_map_get_with_uref(linfo->map.map_fd);
 	if (IS_ERR(map))
 		return PTR_ERR(map);
+	if (map->excl_prog_sha) {
+		err = -EPERM;
+		goto put_map;
+	}
 
 	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||

tools/lib/bpf/gen_loader.c

@@ -160,10 +160,16 @@ void bpf_gen__init(struct bpf_gen *gen, int log_level, int nr_progs, int nr_maps
 
 static int add_data(struct bpf_gen *gen, const void *data, __u32 size)
 {
-	__u32 size8 = roundup(size, 8);
 	__u64 zero = 0;
+	__u32 size8;
 	void *prev;
 
+	if (size > INT32_MAX) {
+		gen->error = -ERANGE;
+		return 0;
+	}
+	size8 = roundup(size, 8);
+
 	if (realloc_data_buf(gen, size8))
 		return 0;
 	prev = gen->data_cur;

tools/testing/selftests/bpf/prog_tests/map_excl.c

@@ -7,6 +7,7 @@
 #include <bpf/btf.h>
 
 #include "map_excl.skel.h"
+#include "bpf_iter_bpf_array_map.skel.h"
 
 #ifndef SHA256_DIGEST_SIZE
 #define SHA256_DIGEST_SIZE	32
@@ -89,6 +90,42 @@ static void test_map_excl_no_map_in_map(void)
 	close(excl_fd);
 }
 
+static void test_map_excl_no_map_iter(void)
+{
+	__u8 hash[SHA256_DIGEST_SIZE] = {};
+	LIBBPF_OPTS(bpf_map_create_opts, excl_opts,
+		    .excl_prog_hash = hash,
+		    .excl_prog_hash_size = sizeof(hash));
+	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	struct bpf_iter_bpf_array_map *skel = NULL;
+	union bpf_iter_link_info linfo;
+	struct bpf_link *link;
+	int excl_fd;
+
+	excl_fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "excl_iter", 4, 8, 3, &excl_opts);
+	if (!ASSERT_OK_FD(excl_fd, "create exclusive map"))
+		return;
+
+	skel = bpf_iter_bpf_array_map__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "bpf_iter_bpf_array_map__open_and_load"))
+		goto out;
+
+	memset(&linfo, 0, sizeof(linfo));
+	linfo.map.map_fd = excl_fd;
+	opts.link_info = &linfo;
+	opts.link_info_len = sizeof(linfo);
+
+	link = bpf_program__attach_iter(skel->progs.dump_bpf_array_map, &opts);
+	if (!ASSERT_ERR_PTR(link, "reject exclusive map as iter target")) {
+		bpf_link__destroy(link);
+		goto out;
+	}
+	ASSERT_EQ(libbpf_get_error(link), -EPERM, "iter attach errno");
+out:
+	bpf_iter_bpf_array_map__destroy(skel);
+	close(excl_fd);
+}
+
 void test_map_excl(void)
 {
 	if (test__start_subtest("map_excl_allowed"))
@@ -97,4 +134,6 @@ void test_map_excl(void)
 		test_map_excl_denied();
 	if (test__start_subtest("map_excl_no_map_in_map"))
 		test_map_excl_no_map_in_map();
+	if (test__start_subtest("map_excl_no_map_iter"))
+		test_map_excl_no_map_iter();
 }

tools/testing/selftests/bpf/progs/verifier_map_ptr.c

@@ -72,17 +72,43 @@ __naked void bpf_map_ptr_write_rejected(void)
 
 /*
  * struct bpf_map starts with the SHA256 hash sha[32] at offset 0 (a readable
- * byte array), followed by the u32 excl field at offset 32. Reading a u32 at
- * offset 33 runs past the end of excl and is rejected.
+ * byte array), the u32 excl field at offset 32, and the ops pointer at offset
+ * 40. Reading a u32 at offset 41 reaches into the middle of the ops pointer,
+ * i.e. a partial pointer access, which is rejected.
  */
 SEC("socket")
 __description("bpf_map_ptr: read non-existent field rejected")
 __failure
-__msg("access beyond the end of member excl (mend:36) in struct bpf_map with off 33 size 4")
+__msg("cannot access ptr member ops with moff 40 in struct bpf_map with off 41 size 4")
 __failure_unpriv
 __msg_unpriv("access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN")
 __flag(BPF_F_ANY_ALIGNMENT)
 __naked void read_non_existent_field_rejected(void)
+{
+	asm volatile ("					\
+	r6 = 0;						\
+	r1 = %[map_array_48b] ll;			\
+	r6 = *(u32*)(r1 + 41);				\
+	r0 = 1;						\
+	exit;						\
+"	:
+	: __imm_addr(map_array_48b)
+	: __clobber_all);
+}
+
+/*
+ * The u32 excl field spans offsets 32..35 (mend 36). Reading a u32 at offset
+ * 33 starts inside excl but extends past its end, which the verifier rejects
+ * as an out-of-bounds scalar access.
+ */
+SEC("socket")
+__description("bpf_map_ptr: read beyond excl field rejected")
+__failure
+__msg("access beyond the end of member excl (mend:36) in struct bpf_map with off 33 size 4")
+__failure_unpriv
+__msg_unpriv("access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN")
+__flag(BPF_F_ANY_ALIGNMENT)
+__naked void read_beyond_excl_field_rejected(void)
 {
 	asm volatile ("					\
 	r6 = 0;						\
@@ -105,7 +131,7 @@ __naked void ptr_read_ops_field_accepted(void)
 	asm volatile ("					\
 	r6 = 0;						\
 	r1 = %[map_array_48b] ll;			\
-	r6 = *(u64*)(r1 + 0);				\
+	r6 = *(u64*)(r1 + 40);				\
 	r0 = 1;						\
 	exit;						\
 "	: