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ima: Avoid blocking in RCU read-side critical section 

commit 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34 upstream.

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>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
GUO Zihua 2024-05-07 01:25:41 +00:00 коммит произвёл Greg Kroah-Hartman
Родитель 0edae06b4c
Коммит a38e02265c
11 изменённых файлов: 34 добавлений и 22 удалений
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2
include/linux/lsm_hook_defs.h
Просмотреть файл

@ -379,7 +379,7 @@ LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **_buffer)
#ifdef CONFIG_AUDIT
LSM_HOOK(int, 0, audit_rule_init, u32 field, u32 op, char *rulestr,
void **lsmrule)
void **lsmrule, gfp_t gfp)
LSM_HOOK(int, 0, audit_rule_known, struct audit_krule *krule)
LSM_HOOK(int, 0, audit_rule_match, u32 secid, u32 field, u32 op, void *lsmrule)
LSM_HOOK(void, LSM_RET_VOID, audit_rule_free, void *lsmrule)

5
include/linux/security.h
Просмотреть файл

@ -1896,7 +1896,8 @@ static inline int security_key_getsecurity(struct key *key, char **_buffer)
#ifdef CONFIG_AUDIT
#ifdef CONFIG_SECURITY
int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule);
int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule,
gfp_t gfp);
int security_audit_rule_known(struct audit_krule *krule);
int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule);
void security_audit_rule_free(void *lsmrule);
@ -1904,7 +1905,7 @@ void security_audit_rule_free(void *lsmrule);
#else
static inline int security_audit_rule_init(u32 field, u32 op, char *rulestr,
void **lsmrule)
void **lsmrule, gfp_t gfp)
{
return 0;
}

5
kernel/auditfilter.c
Просмотреть файл

@ -521,7 +521,8 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
entry->rule.buflen += f_val;
f->lsm_str = str;
err = security_audit_rule_init(f->type, f->op, str,
(void **)&f->lsm_rule);
(void **)&f->lsm_rule,
GFP_KERNEL);
/* Keep currently invalid fields around in case they
* become valid after a policy reload. */
if (err == -EINVAL) {
@ -790,7 +791,7 @@ static inline int audit_dupe_lsm_field(struct audit_field *df,
/* our own (refreshed) copy of lsm_rule */
ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
(void **)&df->lsm_rule);
(void **)&df->lsm_rule, GFP_KERNEL);
/* Keep currently invalid fields around in case they
* become valid after a policy reload. */
if (ret == -EINVAL) {

6
security/apparmor/audit.c
Просмотреть файл

@ -173,7 +173,7 @@ void aa_audit_rule_free(void *vrule)
}
}
int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule, gfp_t gfp)
{
struct aa_audit_rule *rule;
@ -186,14 +186,14 @@ int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
return -EINVAL;
}
rule = kzalloc(sizeof(struct aa_audit_rule), GFP_KERNEL);
rule = kzalloc(sizeof(struct aa_audit_rule), gfp);
if (!rule)
return -ENOMEM;
/* Currently rules are treated as coming from the root ns */
rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr,
GFP_KERNEL, true, false);
gfp, true, false);
if (IS_ERR(rule->label)) {
int err = PTR_ERR(rule->label);
aa_audit_rule_free(rule);

2
security/apparmor/include/audit.h
Просмотреть файл

@ -186,7 +186,7 @@ static inline int complain_error(int error)
}
void aa_audit_rule_free(void *vrule);
int aa_audit_rule_init(u32 field, u32 op, char *rulestr, 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);

2
security/integrity/ima/ima.h
Просмотреть файл

@ -428,7 +428,7 @@ static inline void ima_free_modsig(struct modsig *modsig)
#else
static inline int ima_filter_rule_init(u32 field, u32 op, char *rulestr,
void **lsmrule)
void **lsmrule, gfp_t gfp)
{
return -EINVAL;
}

15
security/integrity/ima/ima_policy.c
Просмотреть файл

@ -370,7 +370,8 @@ static void ima_free_rule(struct ima_rule_entry *entry)
kfree(entry);
}
static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry,
gfp_t gfp)
{
struct ima_rule_entry *nentry;
int i;
@ -379,7 +380,7 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
* Immutable elements are copied over as pointers and data; only
* lsm rules can change
*/
nentry = kmemdup(entry, sizeof(*nentry), GFP_KERNEL);
nentry = kmemdup(entry, sizeof(*nentry), gfp);
if (!nentry)
return NULL;
@ -394,7 +395,8 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
nentry->lsm[i].args_p,
&nentry->lsm[i].rule);
&nentry->lsm[i].rule,
gfp);
if (!nentry->lsm[i].rule)
pr_warn("rule for LSM \'%s\' is undefined\n",
nentry->lsm[i].args_p);
@ -407,7 +409,7 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry)
int i;
struct ima_rule_entry *nentry;
nentry = ima_lsm_copy_rule(entry);
nentry = ima_lsm_copy_rule(entry, GFP_KERNEL);
if (!nentry)
return -ENOMEM;
@ -618,7 +620,7 @@ retry:
}
if (rc == -ESTALE && !rule_reinitialized) {
lsm_rule = ima_lsm_copy_rule(rule);
lsm_rule = ima_lsm_copy_rule(rule, GFP_ATOMIC);
if (lsm_rule) {
rule_reinitialized = true;
goto retry;
@ -1080,7 +1082,8 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry,
entry->lsm[lsm_rule].type = audit_type;
result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal,
entry->lsm[lsm_rule].args_p,
&entry->lsm[lsm_rule].rule);
&entry->lsm[lsm_rule].rule,
GFP_KERNEL);
if (!entry->lsm[lsm_rule].rule) {
pr_warn("rule for LSM \'%s\' is undefined\n",
entry->lsm[lsm_rule].args_p);

6
security/security.c
Просмотреть файл

@ -2587,9 +2587,11 @@ int security_key_getsecurity(struct key *key, char **_buffer)
#ifdef CONFIG_AUDIT
int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule)
int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule,
gfp_t gfp)
{
return call_int_hook(audit_rule_init, 0, field, op, rulestr, lsmrule);
return call_int_hook(audit_rule_init, 0, field, op, rulestr, lsmrule,
gfp);
}
int security_audit_rule_known(struct audit_krule *krule)

4
security/selinux/include/audit.h
Просмотреть файл

@ -18,12 +18,14 @@
* @op: the operater the rule uses
* @rulestr: the text "target" of the rule
* @rule: pointer to the new rule structure returned via this
* @gfp: GFP flag used for kmalloc
*
* Returns 0 if successful, -errno if not. On success, the rule structure
* will be allocated internally. The caller must free this structure with
* selinux_audit_rule_free() after use.
*/
int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **rule);
int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **rule,
gfp_t gfp);
/**
* selinux_audit_rule_free - free an selinux audit rule structure.

5
security/selinux/ss/services.c
Просмотреть файл

@ -3560,7 +3560,8 @@ void selinux_audit_rule_free(void *vrule)
}
}
int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule,
gfp_t gfp)
{
struct selinux_state *state = &selinux_state;
struct selinux_policy *policy;
@ -3601,7 +3602,7 @@ int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
return -EINVAL;
}
tmprule = kzalloc(sizeof(struct selinux_audit_rule), GFP_KERNEL);
tmprule = kzalloc(sizeof(struct selinux_audit_rule), gfp);
if (!tmprule)
return -ENOMEM;

4
security/smack/smack_lsm.c
Просмотреть файл

@ -4487,11 +4487,13 @@ static int smack_post_notification(const struct cred *w_cred,
* @op: required testing operator (=, !=, >, <, ...)
* @rulestr: smack label to be audited
* @vrule: pointer to save our own audit rule representation
* @gfp: type of the memory for the allocation
*
* Prepare to audit cases where (@field @op @rulestr) is true.
* The label to be audited is created if necessay.
*/
static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule,
gfp_t gfp)
{
struct smack_known *skp;
char **rule = (char **)vrule;