apparmor: fix locking when creating a new complain profile.

Break the per cpu buffer atomic section when creating a new null
complain profile. In learning mode this won't matter and we can
safely re-aquire the buffer.

This fixes the following lockdep BUG trace
   nov. 14 14:09:09 cyclope audit[7152]: AVC apparmor="ALLOWED" operation="exec" profile="/usr/sbin/sssd" name="/usr/sbin/adcli" pid=7152 comm="sssd_be" requested_mask="x" denied_mask="x" fsuid=0 ouid=0 target="/usr/sbin/sssd//null-/usr/sbin/adcli"
    nov. 14 14:09:09 cyclope kernel: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747
    nov. 14 14:09:09 cyclope kernel: in_atomic(): 1, irqs_disabled(): 0, pid: 7152, name: sssd_be
    nov. 14 14:09:09 cyclope kernel: 1 lock held by sssd_be/7152:
    nov. 14 14:09:09 cyclope kernel:  #0:  (&sig->cred_guard_mutex){....}, at: [<ffffffff8182d53e>] prepare_bprm_creds+0x4e/0x100
    nov. 14 14:09:09 cyclope kernel: CPU: 3 PID: 7152 Comm: sssd_be Not tainted 4.14.0prahal+intel #150
    nov. 14 14:09:09 cyclope kernel: Hardware name: LENOVO 20CDCTO1WW/20CDCTO1WW, BIOS GQET53WW (1.33 ) 09/15/2017
    nov. 14 14:09:09 cyclope kernel: Call Trace:
    nov. 14 14:09:09 cyclope kernel:  dump_stack+0xb0/0x135
    nov. 14 14:09:09 cyclope kernel:  ? _atomic_dec_and_lock+0x15b/0x15b
    nov. 14 14:09:09 cyclope kernel:  ? lockdep_print_held_locks+0xc4/0x130
    nov. 14 14:09:09 cyclope kernel:  ___might_sleep+0x29c/0x320
    nov. 14 14:09:09 cyclope kernel:  ? rq_clock+0xf0/0xf0
    nov. 14 14:09:09 cyclope kernel:  ? __kernel_text_address+0xd/0x40
    nov. 14 14:09:09 cyclope kernel:  __might_sleep+0x95/0x190
    nov. 14 14:09:09 cyclope kernel:  ? aa_new_null_profile+0x50a/0x960
    nov. 14 14:09:09 cyclope kernel:  __mutex_lock+0x13e/0x1a20
    nov. 14 14:09:09 cyclope kernel:  ? aa_new_null_profile+0x50a/0x960
    nov. 14 14:09:09 cyclope kernel:  ? save_stack+0x43/0xd0
    nov. 14 14:09:09 cyclope kernel:  ? kmem_cache_alloc_trace+0x13f/0x290
    nov. 14 14:09:09 cyclope kernel:  ? mutex_lock_io_nested+0x1880/0x1880
    nov. 14 14:09:09 cyclope kernel:  ? profile_transition+0x932/0x2d40
    nov. 14 14:09:09 cyclope kernel:  ? apparmor_bprm_set_creds+0x1479/0x1f70
    nov. 14 14:09:09 cyclope kernel:  ? security_bprm_set_creds+0x5a/0x80
    nov. 14 14:09:09 cyclope kernel:  ? prepare_binprm+0x366/0x980
    nov. 14 14:09:09 cyclope kernel:  ? do_execveat_common.isra.30+0x12a9/0x2350
    nov. 14 14:09:09 cyclope kernel:  ? SyS_execve+0x2c/0x40
    nov. 14 14:09:09 cyclope kernel:  ? do_syscall_64+0x228/0x650
    nov. 14 14:09:09 cyclope kernel:  ? entry_SYSCALL64_slow_path+0x25/0x25
    nov. 14 14:09:09 cyclope kernel:  ? deactivate_slab.isra.62+0x49d/0x5e0
    nov. 14 14:09:09 cyclope kernel:  ? save_stack_trace+0x16/0x20
    nov. 14 14:09:09 cyclope kernel:  ? init_object+0x88/0x90
    nov. 14 14:09:09 cyclope kernel:  ? ___slab_alloc+0x520/0x590
    nov. 14 14:09:09 cyclope kernel:  ? ___slab_alloc+0x520/0x590
    nov. 14 14:09:09 cyclope kernel:  ? aa_alloc_proxy+0xab/0x200
    nov. 14 14:09:09 cyclope kernel:  ? lock_downgrade+0x7e0/0x7e0
    nov. 14 14:09:09 cyclope kernel:  ? memcg_kmem_get_cache+0x970/0x970
    nov. 14 14:09:09 cyclope kernel:  ? kasan_unpoison_shadow+0x35/0x50
    nov. 14 14:09:09 cyclope kernel:  ? kasan_unpoison_shadow+0x35/0x50
    nov. 14 14:09:09 cyclope kernel:  ? kasan_kmalloc+0xad/0xe0
    nov. 14 14:09:09 cyclope kernel:  ? aa_alloc_proxy+0xab/0x200
    nov. 14 14:09:09 cyclope kernel:  ? kmem_cache_alloc_trace+0x13f/0x290
    nov. 14 14:09:09 cyclope kernel:  ? aa_alloc_proxy+0xab/0x200
    nov. 14 14:09:09 cyclope kernel:  ? aa_alloc_proxy+0xab/0x200
    nov. 14 14:09:09 cyclope kernel:  ? _raw_spin_unlock+0x22/0x30
    nov. 14 14:09:09 cyclope kernel:  ? vec_find+0xa0/0xa0
    nov. 14 14:09:09 cyclope kernel:  ? aa_label_init+0x6f/0x230
    nov. 14 14:09:09 cyclope kernel:  ? __label_insert+0x3e0/0x3e0
    nov. 14 14:09:09 cyclope kernel:  ? kmem_cache_alloc_trace+0x13f/0x290
    nov. 14 14:09:09 cyclope kernel:  ? aa_alloc_profile+0x58/0x200
    nov. 14 14:09:09 cyclope kernel:  mutex_lock_nested+0x16/0x20
    nov. 14 14:09:09 cyclope kernel:  ? mutex_lock_nested+0x16/0x20
    nov. 14 14:09:09 cyclope kernel:  aa_new_null_profile+0x50a/0x960
    nov. 14 14:09:09 cyclope kernel:  ? aa_fqlookupn_profile+0xdc0/0xdc0
    nov. 14 14:09:09 cyclope kernel:  ? aa_compute_fperms+0x4b5/0x640
    nov. 14 14:09:09 cyclope kernel:  ? disconnect.isra.2+0x1b0/0x1b0
    nov. 14 14:09:09 cyclope kernel:  ? aa_str_perms+0x8d/0xe0
    nov. 14 14:09:09 cyclope kernel:  profile_transition+0x932/0x2d40
    nov. 14 14:09:09 cyclope kernel:  ? up_read+0x1a/0x40
    nov. 14 14:09:09 cyclope kernel:  ? ext4_xattr_get+0x15c/0xaf0 [ext4]
    nov. 14 14:09:09 cyclope kernel:  ? x_table_lookup+0x190/0x190
    nov. 14 14:09:09 cyclope kernel:  ? ext4_xattr_ibody_get+0x590/0x590 [ext4]
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock+0x9/0x10
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock+0x9/0x10
    nov. 14 14:09:09 cyclope kernel:  ? ext4_xattr_security_get+0x1a/0x20 [ext4]
    nov. 14 14:09:09 cyclope kernel:  ? __vfs_getxattr+0x6d/0xa0
    nov. 14 14:09:09 cyclope kernel:  ? get_vfs_caps_from_disk+0x114/0x720
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock+0x9/0x10
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock+0x9/0x10
    nov. 14 14:09:09 cyclope kernel:  ? tsc_resume+0x10/0x10
    nov. 14 14:09:09 cyclope kernel:  ? get_vfs_caps_from_disk+0x720/0x720
    nov. 14 14:09:09 cyclope kernel:  ? native_sched_clock_from_tsc+0x201/0x2b0
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock+0x9/0x10
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock_cpu+0x1b/0x170
    nov. 14 14:09:09 cyclope kernel:  ? find_held_lock+0x3c/0x1e0
    nov. 14 14:09:09 cyclope kernel:  ? rb_insert_color_cached+0x1660/0x1660
    nov. 14 14:09:09 cyclope kernel:  apparmor_bprm_set_creds+0x1479/0x1f70
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock+0x9/0x10
    nov. 14 14:09:09 cyclope kernel:  ? handle_onexec+0x31d0/0x31d0
    nov. 14 14:09:09 cyclope kernel:  ? tsc_resume+0x10/0x10
    nov. 14 14:09:09 cyclope kernel:  ? graph_lock+0xd0/0xd0
    nov. 14 14:09:09 cyclope kernel:  ? tsc_resume+0x10/0x10
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock_cpu+0x1b/0x170
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock+0x9/0x10
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock+0x9/0x10
    nov. 14 14:09:09 cyclope kernel:  ? sched_clock_cpu+0x1b/0x170
    nov. 14 14:09:09 cyclope kernel:  ? find_held_lock+0x3c/0x1e0
    nov. 14 14:09:09 cyclope kernel:  security_bprm_set_creds+0x5a/0x80
    nov. 14 14:09:09 cyclope kernel:  prepare_binprm+0x366/0x980
    nov. 14 14:09:09 cyclope kernel:  ? install_exec_creds+0x150/0x150
    nov. 14 14:09:09 cyclope kernel:  ? __might_fault+0x89/0xb0
    nov. 14 14:09:09 cyclope kernel:  ? up_read+0x40/0x40
    nov. 14 14:09:09 cyclope kernel:  ? get_user_arg_ptr.isra.18+0x2c/0x70
    nov. 14 14:09:09 cyclope kernel:  ? count.isra.20.constprop.32+0x7c/0xf0
    nov. 14 14:09:09 cyclope kernel:  do_execveat_common.isra.30+0x12a9/0x2350
    nov. 14 14:09:09 cyclope kernel:  ? prepare_bprm_creds+0x100/0x100
    nov. 14 14:09:09 cyclope kernel:  ? _raw_spin_unlock+0x22/0x30
    nov. 14 14:09:09 cyclope kernel:  ? deactivate_slab.isra.62+0x49d/0x5e0
    nov. 14 14:09:09 cyclope kernel:  ? save_stack_trace+0x16/0x20
    nov. 14 14:09:09 cyclope kernel:  ? init_object+0x88/0x90
    nov. 14 14:09:09 cyclope kernel:  ? ___slab_alloc+0x520/0x590
    nov. 14 14:09:09 cyclope kernel:  ? ___slab_alloc+0x520/0x590
    nov. 14 14:09:09 cyclope kernel:  ? kasan_check_write+0x14/0x20
    nov. 14 14:09:09 cyclope kernel:  ? memcg_kmem_get_cache+0x970/0x970
    nov. 14 14:09:09 cyclope kernel:  ? kasan_unpoison_shadow+0x35/0x50
    nov. 14 14:09:09 cyclope kernel:  ? glob_match+0x730/0x730
    nov. 14 14:09:09 cyclope kernel:  ? kmem_cache_alloc+0x225/0x280
    nov. 14 14:09:09 cyclope kernel:  ? getname_flags+0xb8/0x510
    nov. 14 14:09:09 cyclope kernel:  ? mm_fault_error+0x2e0/0x2e0
    nov. 14 14:09:09 cyclope kernel:  ? getname_flags+0xf6/0x510
    nov. 14 14:09:09 cyclope kernel:  ? ptregs_sys_vfork+0x10/0x10
    nov. 14 14:09:09 cyclope kernel:  SyS_execve+0x2c/0x40
    nov. 14 14:09:09 cyclope kernel:  do_syscall_64+0x228/0x650
    nov. 14 14:09:09 cyclope kernel:  ? syscall_return_slowpath+0x2f0/0x2f0
    nov. 14 14:09:09 cyclope kernel:  ? syscall_return_slowpath+0x167/0x2f0
    nov. 14 14:09:09 cyclope kernel:  ? prepare_exit_to_usermode+0x220/0x220
    nov. 14 14:09:09 cyclope kernel:  ? prepare_exit_to_usermode+0xda/0x220
    nov. 14 14:09:09 cyclope kernel:  ? perf_trace_sys_enter+0x1060/0x1060
    nov. 14 14:09:09 cyclope kernel:  ? __put_user_4+0x1c/0x30
    nov. 14 14:09:09 cyclope kernel:  entry_SYSCALL64_slow_path+0x25/0x25
    nov. 14 14:09:09 cyclope kernel: RIP: 0033:0x7f9320f23637
    nov. 14 14:09:09 cyclope kernel: RSP: 002b:00007fff783be338 EFLAGS: 00000202 ORIG_RAX: 000000000000003b
    nov. 14 14:09:09 cyclope kernel: RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9320f23637
    nov. 14 14:09:09 cyclope kernel: RDX: 0000558c35002a70 RSI: 0000558c3505bd10 RDI: 0000558c35018b90
    nov. 14 14:09:09 cyclope kernel: RBP: 0000558c34b63ae8 R08: 0000558c3505bd10 R09: 0000000000000080
    nov. 14 14:09:09 cyclope kernel: R10: 0000000000000095 R11: 0000000000000202 R12: 0000000000000001
    nov. 14 14:09:09 cyclope kernel: R13: 0000558c35018b90 R14: 0000558c3505bd18 R15: 0000558c3505bd10

Fixes: 4227c333f65c ("apparmor: Move path lookup to using preallocated buffers")
BugLink: http://bugs.launchpad.net/bugs/173228
Reported-by: Alban Browaeys <prahal@yahoo.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index ad456546df5b..04ba9d0718ea 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -561,9 +561,21 @@ static struct aa_label *profile_transition(struct aa_profile *profile,
 		}
 	} else if (COMPLAIN_MODE(profile)) {
 		/* no exec permission - learning mode */
-		struct aa_profile *new_profile = aa_new_null_profile(profile,
-							      false, name,
-							      GFP_ATOMIC);
+		struct aa_profile *new_profile = NULL;
+		char *n = kstrdup(name, GFP_ATOMIC);
+
+		if (n) {
+			/* name is ptr into buffer */
+			long pos = name - buffer;
+			/* break per cpu buffer hold */
+			put_buffers(buffer);
+			new_profile = aa_new_null_profile(profile, false, n,
+							  GFP_KERNEL);
+			get_buffers(buffer);
+			name = buffer + pos;
+			strcpy((char *)name, n);
+			kfree(n);
+		}
 		if (!new_profile) {
 			error = -ENOMEM;
 			info = "could not create null profile";