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authorGUO Zihua <guozihua@huawei.com>2024-05-07 04:25:41 +0300
committerPaul Moore <paul@paul-moore.com>2024-06-13 21:26:50 +0300
commit9a95c5bfbf02a0a7f5983280fe284a0ff0836c34 (patch)
tree46e2fe55b0b3cbd9baca7f77b15bb9378160c751 /security
parent83a7eefedc9b56fe7bfeff13b6c7356688ffa670 (diff)
downloadlinux-9a95c5bfbf02a0a7f5983280fe284a0ff0836c34.tar.xz
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 c7423dbdbc9e ("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: c7423dbdbc9e ("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>
Diffstat (limited to 'security')
-rw-r--r--security/apparmor/audit.c6
-rw-r--r--security/apparmor/include/audit.h2
-rw-r--r--security/integrity/ima/ima.h2
-rw-r--r--security/integrity/ima/ima_policy.c15
-rw-r--r--security/security.c6
-rw-r--r--security/selinux/include/audit.h4
-rw-r--r--security/selinux/ss/services.c5
-rw-r--r--security/smack/smack_lsm.c4
8 files changed, 27 insertions, 17 deletions
diff --git a/security/apparmor/audit.c b/security/apparmor/audit.c
index 45beb1c5f747..6b5181c668b5 100644
--- a/security/apparmor/audit.c
+++ b/security/apparmor/audit.c
@@ -217,7 +217,7 @@ 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;
@@ -230,14 +230,14 @@ 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);
diff --git a/security/apparmor/include/audit.h b/security/apparmor/include/audit.h
index acbb03b9bd25..0c8cc86b417b 100644
--- a/security/apparmor/include/audit.h
+++ b/security/apparmor/include/audit.h
@@ -200,7 +200,7 @@ 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);
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 3e568126cd48..c51e24d24d1e 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -546,7 +546,7 @@ 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;
}
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index c0556907c2e6..09da8e639239 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -401,7 +401,8 @@ 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;
@@ -410,7 +411,7 @@ 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;
@@ -425,7 +426,8 @@ 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);
@@ -438,7 +440,7 @@ 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;
@@ -664,7 +666,7 @@ 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;
@@ -1140,7 +1142,8 @@ 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);
diff --git a/security/security.c b/security/security.c
index e5da848c50b9..e5ca08789f74 100644
--- a/security/security.c
+++ b/security/security.c
@@ -5332,15 +5332,17 @@ void security_key_post_create_or_update(struct key *keyring, struct key *key,
* @op: rule operator
* @rulestr: rule context
* @lsmrule: receive buffer for audit rule struct
+ * @gfp: GFP flag used for kmalloc
*
* Allocate and initialize an LSM audit rule structure.
*
* Return: Return 0 if @lsmrule has been successfully set, -EINVAL in case of
* an invalid rule.
*/
-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, field, op, rulestr, lsmrule);
+ return call_int_hook(audit_rule_init, field, op, rulestr, lsmrule, gfp);
}
/**
diff --git a/security/selinux/include/audit.h b/security/selinux/include/audit.h
index 52aca71210b4..29c7d4c86f6d 100644
--- a/security/selinux/include/audit.h
+++ b/security/selinux/include/audit.h
@@ -21,12 +21,14 @@
* @op: the operator 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.
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index f20e1968b7f7..e33e55384b75 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -3507,7 +3507,8 @@ 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;
@@ -3548,7 +3549,7 @@ 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;
context_init(&tmprule->au_ctxt);
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 70ba2841e181..f5cbec1e6a92 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4693,11 +4693,13 @@ 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;