selftests/bpf: Test rhtab kptr cancellation semanticsgrafted

Resizable hash-map updates and deletions must not perform full special-field
destruction in their caller context. In particular, a referenced kptr must
remain attached to the allocation until the memory allocator destructor can
release it safely.

Add separate coverage for both affected paths. The update test stores a task
kptr, replaces the ordinary value bytes with BPF_EXIST, and verifies that the
kptr survived. The delete test removes an element and exchanges its kptr
through the still-valid map-value pointer before the allocation is reclaimed.

Both cases observe a NULL kptr when rhtab uses bpf_obj_free_fields(). They
recover and release the reference after rhtab switches to cancellation
semantics.

Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
[ kkd: Split update and delete coverage and rewrote the commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904104203.345917-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 100 insertions, 0 deletions

diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c
new file mode 100644
index 000000000..495bb765d
--- /dev/null
+++ b/security/ipe/ipe.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
+ */
+#include <uapi/linux/lsm.h>
+
+#include "ipe.h"
+#include "eval.h"
+#include "hooks.h"
+
+extern const char *const ipe_boot_policy;
+bool ipe_enabled;
+
+static struct lsm_blob_sizes ipe_blobs __ro_after_init = {
+	.lbs_superblock = sizeof(struct ipe_superblock),
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+	.lbs_bdev = sizeof(struct ipe_bdev),
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
+	.lbs_inode = sizeof(struct ipe_inode),
+#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
+};
+
+static const struct lsm_id ipe_lsmid = {
+	.name = "ipe",
+	.id = LSM_ID_IPE,
+};
+
+struct ipe_superblock *ipe_sb(const struct super_block *sb)
+{
+	return sb->s_security + ipe_blobs.lbs_superblock;
+}
+
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+struct ipe_bdev *ipe_bdev(struct block_device *b)
+{
+	return b->bd_security + ipe_blobs.lbs_bdev;
+}
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+
+#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
+struct ipe_inode *ipe_inode(const struct inode *inode)
+{
+	return inode->i_security + ipe_blobs.lbs_inode;
+}
+#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
+
+static struct security_hook_list ipe_hooks[] __ro_after_init = {
+	LSM_HOOK_INIT(bprm_check_security, ipe_bprm_check_security),
+	LSM_HOOK_INIT(bprm_creds_for_exec, ipe_bprm_creds_for_exec),
+	LSM_HOOK_INIT(mmap_file, ipe_mmap_file),
+	LSM_HOOK_INIT(file_mprotect, ipe_file_mprotect),
+	LSM_HOOK_INIT(kernel_read_file, ipe_kernel_read_file),
+	LSM_HOOK_INIT(kernel_load_data, ipe_kernel_load_data),
+	LSM_HOOK_INIT(initramfs_populated, ipe_unpack_initramfs),
+#ifdef CONFIG_IPE_PROP_DM_VERITY
+	LSM_HOOK_INIT(bdev_free_security, ipe_bdev_free_security),
+	LSM_HOOK_INIT(bdev_setintegrity, ipe_bdev_setintegrity),
+#endif /* CONFIG_IPE_PROP_DM_VERITY */
+#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
+	LSM_HOOK_INIT(inode_setintegrity, ipe_inode_setintegrity),
+#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
+};
+
+/**
+ * ipe_init() - Entry point of IPE.
+ *
+ * This is called at LSM init, which happens occurs early during kernel
+ * start up. During this phase, IPE registers its hooks and loads the
+ * builtin boot policy.
+ *
+ * Return:
+ * * %0		- OK
+ * * %-ENOMEM	- Out of memory (OOM)
+ */
+static int __init ipe_init(void)
+{
+	struct ipe_policy *p = NULL;
+
+	security_add_hooks(ipe_hooks, ARRAY_SIZE(ipe_hooks), &ipe_lsmid);
+	ipe_enabled = true;
+
+	if (ipe_boot_policy) {
+		p = ipe_new_policy(ipe_boot_policy, strlen(ipe_boot_policy),
+				   NULL, 0);
+		if (IS_ERR(p))
+			return PTR_ERR(p);
+
+		rcu_assign_pointer(ipe_active_policy, p);
+	}
+
+	return 0;
+}
+
+DEFINE_LSM(ipe) = {
+	.id = &ipe_lsmid,
+	.init = ipe_init,
+	.blobs = &ipe_blobs,
+	.initcall_fs = ipe_init_securityfs,
+};