[RFC PATCH v2] selinux: Fix kmemleak after disabling selinux runtime
From: Chen Jun
Date: Wed Oct 28 2020 - 21:21:32 EST
From: Chen Jun <c00424029@xxxxxxxxxx>
Kmemleak will report a problem after using
"echo 1 > /sys/fs/selinux/disable" to disable selinux on runtime.
kmemleak report：
unreferenced object 0xffff901281c208a0 (size 96):
comm "swapper/0", pid 1, jiffies 4294668265 (age 692.799s)
hex dump (first 32 bytes):
00 40 c8 81 12 90 ff ff 03 00 00 00 05 00 00 00 .@..............
03 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<0000000014622ef8>] selinux_sb_alloc_security+0x1b/0xa0
[<00000000044914e1>] security_sb_alloc+0x1d/0x30
[<000000009f9d5ffd>] alloc_super+0xa7/0x310
[<000000003c5f0b5b>] sget_fc+0xca/0x230
[<00000000367a9996>] vfs_get_super+0x37/0x110
[<000000001c47e818>] vfs_get_tree+0x20/0xc0
[<00000000d239b404>] fc_mount+0x9/0x30
[<00000000708a102f>] vfs_kern_mount.part.36+0x6a/0x80
[<000000005db542fe>] kern_mount+0x1b/0x30
[<0000000051919f9f>] init_sel_fs+0x8b/0x119
[<000000000f328fe0>] do_one_initcall+0x3f/0x1d0
[<000000008a6ceb81>] kernel_init_freeable+0x1b4/0x1f2
[<000000003a425dcd>] kernel_init+0x5/0x110
[<000000004e8d6c9d>] ret_from_fork+0x22/0x30
"echo 1 > /sys/fs/selinux/disable" will delete the hooks.
Any memory alloced by calling HOOKFUNCTION (like call_int_hook(sb_alloc_security, 0, sb))
has no chance to be freed after deleting hooks.
Add a flag to mark a hook not be delete when deleting hooks.
Signed-off-by: Chen Jun <chenjun102@xxxxxxxxxx>
---
include/linux/lsm_hooks.h | 6 +++++-
security/selinux/hooks.c | 20 ++++++++++----------
2 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index c503f7ab8afb..85de731b0c74 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1554,6 +1554,7 @@ struct security_hook_list {
struct hlist_head *head;
union security_list_options hook;
char *lsm;
+ bool no_del;
} __randomize_layout;
/*
@@ -1582,6 +1583,8 @@ struct lsm_blob_sizes {
*/
#define LSM_HOOK_INIT(HEAD, HOOK) \
{ .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } }
+#define LSM_HOOK_INIT_NO_DEL(HEAD, HOOK) \
+ { .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK }, .no_del = 1 }
extern struct security_hook_heads security_hook_heads;
extern char *lsm_names;
@@ -1638,7 +1641,8 @@ static inline void security_delete_hooks(struct security_hook_list *hooks,
int i;
for (i = 0; i < count; i++)
- hlist_del_rcu(&hooks[i].list);
+ if (!hooks[i].no_del)
+ hlist_del_rcu(&hooks[i].list);
}
#endif /* CONFIG_SECURITY_SELINUX_DISABLE */
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6b1826fc3658..daff084fd1c7 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6974,8 +6974,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(bprm_committing_creds, selinux_bprm_committing_creds),
LSM_HOOK_INIT(bprm_committed_creds, selinux_bprm_committed_creds),
- LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
- LSM_HOOK_INIT(sb_free_mnt_opts, selinux_free_mnt_opts),
+ LSM_HOOK_INIT_NO_DEL(sb_free_security, selinux_sb_free_security),
+ LSM_HOOK_INIT_NO_DEL(sb_free_mnt_opts, selinux_free_mnt_opts),
LSM_HOOK_INIT(sb_remount, selinux_sb_remount),
LSM_HOOK_INIT(sb_kern_mount, selinux_sb_kern_mount),
LSM_HOOK_INIT(sb_show_options, selinux_sb_show_options),
@@ -7081,7 +7081,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ismaclabel, selinux_ismaclabel),
LSM_HOOK_INIT(secctx_to_secid, selinux_secctx_to_secid),
- LSM_HOOK_INIT(release_secctx, selinux_release_secctx),
+ LSM_HOOK_INIT_NO_DEL(release_secctx, selinux_release_secctx),
LSM_HOOK_INIT(inode_invalidate_secctx, selinux_inode_invalidate_secctx),
LSM_HOOK_INIT(inode_notifysecctx, selinux_inode_notifysecctx),
LSM_HOOK_INIT(inode_setsecctx, selinux_inode_setsecctx),
@@ -7107,7 +7107,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(socket_getpeersec_stream,
selinux_socket_getpeersec_stream),
LSM_HOOK_INIT(socket_getpeersec_dgram, selinux_socket_getpeersec_dgram),
- LSM_HOOK_INIT(sk_free_security, selinux_sk_free_security),
+ LSM_HOOK_INIT_NO_DEL(sk_free_security, selinux_sk_free_security),
LSM_HOOK_INIT(sk_clone_security, selinux_sk_clone_security),
LSM_HOOK_INIT(sk_getsecid, selinux_sk_getsecid),
LSM_HOOK_INIT(sock_graft, selinux_sock_graft),
@@ -7121,7 +7121,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(secmark_refcount_inc, selinux_secmark_refcount_inc),
LSM_HOOK_INIT(secmark_refcount_dec, selinux_secmark_refcount_dec),
LSM_HOOK_INIT(req_classify_flow, selinux_req_classify_flow),
- LSM_HOOK_INIT(tun_dev_free_security, selinux_tun_dev_free_security),
+ LSM_HOOK_INIT_NO_DEL(tun_dev_free_security, selinux_tun_dev_free_security),
LSM_HOOK_INIT(tun_dev_create, selinux_tun_dev_create),
LSM_HOOK_INIT(tun_dev_attach_queue, selinux_tun_dev_attach_queue),
LSM_HOOK_INIT(tun_dev_attach, selinux_tun_dev_attach),
@@ -7130,7 +7130,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ib_pkey_access, selinux_ib_pkey_access),
LSM_HOOK_INIT(ib_endport_manage_subnet,
selinux_ib_endport_manage_subnet),
- LSM_HOOK_INIT(ib_free_security, selinux_ib_free_security),
+ LSM_HOOK_INIT_NO_DEL(ib_free_security, selinux_ib_free_security),
#endif
#ifdef CONFIG_SECURITY_NETWORK_XFRM
LSM_HOOK_INIT(xfrm_policy_free_security, selinux_xfrm_policy_free),
@@ -7144,7 +7144,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
#endif
#ifdef CONFIG_KEYS
- LSM_HOOK_INIT(key_free, selinux_key_free),
+ LSM_HOOK_INIT_NO_DEL(key_free, selinux_key_free),
LSM_HOOK_INIT(key_permission, selinux_key_permission),
LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
#ifdef CONFIG_KEY_NOTIFICATIONS
@@ -7162,13 +7162,13 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(bpf, selinux_bpf),
LSM_HOOK_INIT(bpf_map, selinux_bpf_map),
LSM_HOOK_INIT(bpf_prog, selinux_bpf_prog),
- LSM_HOOK_INIT(bpf_map_free_security, selinux_bpf_map_free),
- LSM_HOOK_INIT(bpf_prog_free_security, selinux_bpf_prog_free),
+ LSM_HOOK_INIT_NO_DEL(bpf_map_free_security, selinux_bpf_map_free),
+ LSM_HOOK_INIT_NO_DEL(bpf_prog_free_security, selinux_bpf_prog_free),
#endif
#ifdef CONFIG_PERF_EVENTS
LSM_HOOK_INIT(perf_event_open, selinux_perf_event_open),
- LSM_HOOK_INIT(perf_event_free, selinux_perf_event_free),
+ LSM_HOOK_INIT_NO_DEL(perf_event_free, selinux_perf_event_free),
LSM_HOOK_INIT(perf_event_read, selinux_perf_event_read),
LSM_HOOK_INIT(perf_event_write, selinux_perf_event_write),
#endif
--
2.25.0