linux/security/apparmor/include/audit.h
GUO Zihua 9a95c5bfbf ima: Avoid blocking in RCU read-side critical section
A panic happens in ima_match_policy:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
PGD 42f873067 P4D 0
Oops: 0000 [#1] SMP NOPTI
CPU: 5 PID: 1286325 Comm: kubeletmonit.sh
Kdump: loaded Tainted: P
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
               BIOS 0.0.0 02/06/2015
RIP: 0010:ima_match_policy+0x84/0x450
Code: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39
      7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d
      f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea
      44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f
RSP: 0018:ff71570009e07a80 EFLAGS: 00010207
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200
RDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739
R10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970
R13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001
FS:  00007f5195b51740(0000)
GS:ff3e278b12d40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ima_get_action+0x22/0x30
 process_measurement+0xb0/0x830
 ? page_add_file_rmap+0x15/0x170
 ? alloc_set_pte+0x269/0x4c0
 ? prep_new_page+0x81/0x140
 ? simple_xattr_get+0x75/0xa0
 ? selinux_file_open+0x9d/0xf0
 ima_file_check+0x64/0x90
 path_openat+0x571/0x1720
 do_filp_open+0x9b/0x110
 ? page_counter_try_charge+0x57/0xc0
 ? files_cgroup_alloc_fd+0x38/0x60
 ? __alloc_fd+0xd4/0x250
 ? do_sys_open+0x1bd/0x250
 do_sys_open+0x1bd/0x250
 do_syscall_64+0x5d/0x1d0
 entry_SYSCALL_64_after_hwframe+0x65/0xca

Commit c7423dbdbc ("ima: Handle -ESTALE returned by
ima_filter_rule_match()") introduced call to ima_lsm_copy_rule within a
RCU read-side critical section which contains kmalloc with GFP_KERNEL.
This implies a possible sleep and violates limitations of RCU read-side
critical sections on non-PREEMPT systems.

Sleeping within RCU read-side critical section might cause
synchronize_rcu() returning early and break RCU protection, allowing a
UAF to happen.

The root cause of this issue could be described as follows:
|	Thread A	|	Thread B	|
|			|ima_match_policy	|
|			|  rcu_read_lock	|
|ima_lsm_update_rule	|			|
|  synchronize_rcu	|			|
|			|    kmalloc(GFP_KERNEL)|
|			|      sleep		|
==> synchronize_rcu returns early
|  kfree(entry)		|			|
|			|    entry = entry->next|
==> UAF happens and entry now becomes NULL (or could be anything).
|			|    entry->action	|
==> Accessing entry might cause panic.

To fix this issue, we are converting all kmalloc that is called within
RCU read-side critical section to use GFP_ATOMIC.

Fixes: c7423dbdbc ("ima: Handle -ESTALE returned by ima_filter_rule_match()")
Cc: stable@vger.kernel.org
Signed-off-by: GUO Zihua <guozihua@huawei.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2024-06-13 14:26:50 -04:00

208 lines
4.8 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* AppArmor security module
*
* This file contains AppArmor auditing function definitions.
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2010 Canonical Ltd.
*/
#ifndef __AA_AUDIT_H
#define __AA_AUDIT_H
#include <linux/audit.h>
#include <linux/fs.h>
#include <linux/lsm_audit.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include "file.h"
#include "label.h"
extern const char *const audit_mode_names[];
#define AUDIT_MAX_INDEX 5
enum audit_mode {
AUDIT_NORMAL, /* follow normal auditing of accesses */
AUDIT_QUIET_DENIED, /* quiet all denied access messages */
AUDIT_QUIET, /* quiet all messages */
AUDIT_NOQUIET, /* do not quiet audit messages */
AUDIT_ALL /* audit all accesses */
};
enum audit_type {
AUDIT_APPARMOR_AUDIT,
AUDIT_APPARMOR_ALLOWED,
AUDIT_APPARMOR_DENIED,
AUDIT_APPARMOR_HINT,
AUDIT_APPARMOR_STATUS,
AUDIT_APPARMOR_ERROR,
AUDIT_APPARMOR_KILL,
AUDIT_APPARMOR_AUTO
};
#define OP_NULL NULL
#define OP_SYSCTL "sysctl"
#define OP_CAPABLE "capable"
#define OP_UNLINK "unlink"
#define OP_MKDIR "mkdir"
#define OP_RMDIR "rmdir"
#define OP_MKNOD "mknod"
#define OP_TRUNC "truncate"
#define OP_LINK "link"
#define OP_SYMLINK "symlink"
#define OP_RENAME_SRC "rename_src"
#define OP_RENAME_DEST "rename_dest"
#define OP_CHMOD "chmod"
#define OP_CHOWN "chown"
#define OP_GETATTR "getattr"
#define OP_OPEN "open"
#define OP_FRECEIVE "file_receive"
#define OP_FPERM "file_perm"
#define OP_FLOCK "file_lock"
#define OP_FMMAP "file_mmap"
#define OP_FMPROT "file_mprotect"
#define OP_INHERIT "file_inherit"
#define OP_PIVOTROOT "pivotroot"
#define OP_MOUNT "mount"
#define OP_UMOUNT "umount"
#define OP_CREATE "create"
#define OP_POST_CREATE "post_create"
#define OP_BIND "bind"
#define OP_CONNECT "connect"
#define OP_LISTEN "listen"
#define OP_ACCEPT "accept"
#define OP_SENDMSG "sendmsg"
#define OP_RECVMSG "recvmsg"
#define OP_GETSOCKNAME "getsockname"
#define OP_GETPEERNAME "getpeername"
#define OP_GETSOCKOPT "getsockopt"
#define OP_SETSOCKOPT "setsockopt"
#define OP_SHUTDOWN "socket_shutdown"
#define OP_PTRACE "ptrace"
#define OP_SIGNAL "signal"
#define OP_EXEC "exec"
#define OP_CHANGE_HAT "change_hat"
#define OP_CHANGE_PROFILE "change_profile"
#define OP_CHANGE_ONEXEC "change_onexec"
#define OP_STACK "stack"
#define OP_STACK_ONEXEC "stack_onexec"
#define OP_SETPROCATTR "setprocattr"
#define OP_SETRLIMIT "setrlimit"
#define OP_PROF_REPL "profile_replace"
#define OP_PROF_LOAD "profile_load"
#define OP_PROF_RM "profile_remove"
#define OP_USERNS_CREATE "userns_create"
#define OP_URING_OVERRIDE "uring_override"
#define OP_URING_SQPOLL "uring_sqpoll"
struct apparmor_audit_data {
int error;
int type;
u16 class;
const char *op;
const struct cred *subj_cred;
struct aa_label *subj_label;
const char *name;
const char *info;
u32 request;
u32 denied;
union {
/* these entries require a custom callback fn */
struct {
struct aa_label *peer;
union {
struct {
const char *target;
kuid_t ouid;
} fs;
struct {
int rlim;
unsigned long max;
} rlim;
struct {
int signal;
int unmappedsig;
};
struct {
int type, protocol;
struct sock *peer_sk;
void *addr;
int addrlen;
} net;
};
};
struct {
struct aa_profile *profile;
const char *ns;
long pos;
} iface;
struct {
const char *src_name;
const char *type;
const char *trans;
const char *data;
unsigned long flags;
} mnt;
struct {
struct aa_label *target;
} uring;
};
struct common_audit_data common;
};
/* macros for dealing with apparmor_audit_data structure */
#define aad(SA) (container_of(SA, struct apparmor_audit_data, common))
#define aad_of_va(VA) aad((struct common_audit_data *)(VA))
#define DEFINE_AUDIT_DATA(NAME, T, C, X) \
/* TODO: cleanup audit init so we don't need _aad = {0,} */ \
struct apparmor_audit_data NAME = { \
.class = (C), \
.op = (X), \
.common.type = (T), \
.common.u.tsk = NULL, \
.common.apparmor_audit_data = &NAME, \
};
void aa_audit_msg(int type, struct apparmor_audit_data *ad,
void (*cb) (struct audit_buffer *, void *));
int aa_audit(int type, struct aa_profile *profile,
struct apparmor_audit_data *ad,
void (*cb) (struct audit_buffer *, void *));
#define aa_audit_error(ERROR, AD, CB) \
({ \
(AD)->error = (ERROR); \
aa_audit_msg(AUDIT_APPARMOR_ERROR, (AD), (CB)); \
(AD)->error; \
})
static inline int complain_error(int error)
{
if (error == -EPERM || error == -EACCES)
return 0;
return error;
}
void aa_audit_rule_free(void *vrule);
int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule, gfp_t gfp);
int aa_audit_rule_known(struct audit_krule *rule);
int aa_audit_rule_match(u32 sid, u32 field, u32 op, void *vrule);
#endif /* __AA_AUDIT_H */