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 Commitc7423dbdbc
("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:
Родитель
0edae06b4c
Коммит
a38e02265c
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@ -379,7 +379,7 @@ LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **_buffer)
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#ifdef CONFIG_AUDIT
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#ifdef CONFIG_AUDIT
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LSM_HOOK(int, 0, audit_rule_init, u32 field, u32 op, char *rulestr,
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LSM_HOOK(int, 0, audit_rule_init, u32 field, u32 op, char *rulestr,
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void **lsmrule)
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void **lsmrule, gfp_t gfp)
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LSM_HOOK(int, 0, audit_rule_known, struct audit_krule *krule)
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LSM_HOOK(int, 0, audit_rule_known, struct audit_krule *krule)
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LSM_HOOK(int, 0, audit_rule_match, u32 secid, u32 field, u32 op, void *lsmrule)
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LSM_HOOK(int, 0, audit_rule_match, u32 secid, u32 field, u32 op, void *lsmrule)
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LSM_HOOK(void, LSM_RET_VOID, audit_rule_free, void *lsmrule)
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LSM_HOOK(void, LSM_RET_VOID, audit_rule_free, void *lsmrule)
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@ -1896,7 +1896,8 @@ static inline int security_key_getsecurity(struct key *key, char **_buffer)
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#ifdef CONFIG_AUDIT
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#ifdef CONFIG_AUDIT
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#ifdef CONFIG_SECURITY
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#ifdef CONFIG_SECURITY
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int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule);
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int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule,
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gfp_t gfp);
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int security_audit_rule_known(struct audit_krule *krule);
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int security_audit_rule_known(struct audit_krule *krule);
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int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule);
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int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule);
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void security_audit_rule_free(void *lsmrule);
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void security_audit_rule_free(void *lsmrule);
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@ -1904,7 +1905,7 @@ void security_audit_rule_free(void *lsmrule);
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#else
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#else
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static inline int security_audit_rule_init(u32 field, u32 op, char *rulestr,
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static inline int security_audit_rule_init(u32 field, u32 op, char *rulestr,
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void **lsmrule)
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void **lsmrule, gfp_t gfp)
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{
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{
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return 0;
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return 0;
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}
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}
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@ -521,7 +521,8 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
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entry->rule.buflen += f_val;
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entry->rule.buflen += f_val;
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f->lsm_str = str;
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f->lsm_str = str;
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err = security_audit_rule_init(f->type, f->op, str,
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err = security_audit_rule_init(f->type, f->op, str,
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(void **)&f->lsm_rule);
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(void **)&f->lsm_rule,
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GFP_KERNEL);
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/* Keep currently invalid fields around in case they
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/* Keep currently invalid fields around in case they
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* become valid after a policy reload. */
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* become valid after a policy reload. */
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if (err == -EINVAL) {
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if (err == -EINVAL) {
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@ -790,7 +791,7 @@ static inline int audit_dupe_lsm_field(struct audit_field *df,
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/* our own (refreshed) copy of lsm_rule */
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/* our own (refreshed) copy of lsm_rule */
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ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
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ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
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(void **)&df->lsm_rule);
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(void **)&df->lsm_rule, GFP_KERNEL);
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/* Keep currently invalid fields around in case they
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/* Keep currently invalid fields around in case they
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* become valid after a policy reload. */
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* become valid after a policy reload. */
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if (ret == -EINVAL) {
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if (ret == -EINVAL) {
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@ -173,7 +173,7 @@ void aa_audit_rule_free(void *vrule)
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}
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}
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}
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}
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int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
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int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule, gfp_t gfp)
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{
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{
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struct aa_audit_rule *rule;
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struct aa_audit_rule *rule;
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@ -186,14 +186,14 @@ int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
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return -EINVAL;
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return -EINVAL;
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}
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}
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rule = kzalloc(sizeof(struct aa_audit_rule), GFP_KERNEL);
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rule = kzalloc(sizeof(struct aa_audit_rule), gfp);
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if (!rule)
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if (!rule)
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return -ENOMEM;
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return -ENOMEM;
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/* Currently rules are treated as coming from the root ns */
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/* Currently rules are treated as coming from the root ns */
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rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr,
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rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr,
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GFP_KERNEL, true, false);
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gfp, true, false);
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if (IS_ERR(rule->label)) {
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if (IS_ERR(rule->label)) {
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int err = PTR_ERR(rule->label);
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int err = PTR_ERR(rule->label);
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aa_audit_rule_free(rule);
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aa_audit_rule_free(rule);
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@ -186,7 +186,7 @@ static inline int complain_error(int error)
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}
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}
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void aa_audit_rule_free(void *vrule);
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void aa_audit_rule_free(void *vrule);
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int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule);
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int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule, gfp_t gfp);
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int aa_audit_rule_known(struct audit_krule *rule);
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int aa_audit_rule_known(struct audit_krule *rule);
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int aa_audit_rule_match(u32 sid, u32 field, u32 op, void *vrule);
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int aa_audit_rule_match(u32 sid, u32 field, u32 op, void *vrule);
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@ -428,7 +428,7 @@ static inline void ima_free_modsig(struct modsig *modsig)
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#else
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#else
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static inline int ima_filter_rule_init(u32 field, u32 op, char *rulestr,
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static inline int ima_filter_rule_init(u32 field, u32 op, char *rulestr,
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void **lsmrule)
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void **lsmrule, gfp_t gfp)
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{
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{
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return -EINVAL;
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return -EINVAL;
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}
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}
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@ -370,7 +370,8 @@ static void ima_free_rule(struct ima_rule_entry *entry)
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kfree(entry);
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kfree(entry);
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}
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}
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static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
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static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry,
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gfp_t gfp)
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{
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{
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struct ima_rule_entry *nentry;
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struct ima_rule_entry *nentry;
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int i;
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int i;
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@ -379,7 +380,7 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
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* Immutable elements are copied over as pointers and data; only
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* Immutable elements are copied over as pointers and data; only
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* lsm rules can change
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* lsm rules can change
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*/
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*/
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nentry = kmemdup(entry, sizeof(*nentry), GFP_KERNEL);
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nentry = kmemdup(entry, sizeof(*nentry), gfp);
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if (!nentry)
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if (!nentry)
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return NULL;
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return NULL;
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@ -394,7 +395,8 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
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ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
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ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
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nentry->lsm[i].args_p,
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nentry->lsm[i].args_p,
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&nentry->lsm[i].rule);
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&nentry->lsm[i].rule,
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gfp);
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if (!nentry->lsm[i].rule)
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if (!nentry->lsm[i].rule)
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pr_warn("rule for LSM \'%s\' is undefined\n",
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pr_warn("rule for LSM \'%s\' is undefined\n",
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nentry->lsm[i].args_p);
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nentry->lsm[i].args_p);
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@ -407,7 +409,7 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry)
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int i;
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int i;
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struct ima_rule_entry *nentry;
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struct ima_rule_entry *nentry;
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nentry = ima_lsm_copy_rule(entry);
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nentry = ima_lsm_copy_rule(entry, GFP_KERNEL);
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if (!nentry)
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if (!nentry)
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return -ENOMEM;
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return -ENOMEM;
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@ -618,7 +620,7 @@ retry:
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}
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}
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if (rc == -ESTALE && !rule_reinitialized) {
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if (rc == -ESTALE && !rule_reinitialized) {
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lsm_rule = ima_lsm_copy_rule(rule);
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lsm_rule = ima_lsm_copy_rule(rule, GFP_ATOMIC);
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if (lsm_rule) {
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if (lsm_rule) {
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rule_reinitialized = true;
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rule_reinitialized = true;
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goto retry;
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goto retry;
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@ -1080,7 +1082,8 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry,
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entry->lsm[lsm_rule].type = audit_type;
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entry->lsm[lsm_rule].type = audit_type;
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result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal,
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result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal,
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entry->lsm[lsm_rule].args_p,
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entry->lsm[lsm_rule].args_p,
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&entry->lsm[lsm_rule].rule);
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&entry->lsm[lsm_rule].rule,
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GFP_KERNEL);
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if (!entry->lsm[lsm_rule].rule) {
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if (!entry->lsm[lsm_rule].rule) {
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pr_warn("rule for LSM \'%s\' is undefined\n",
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pr_warn("rule for LSM \'%s\' is undefined\n",
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entry->lsm[lsm_rule].args_p);
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entry->lsm[lsm_rule].args_p);
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@ -2587,9 +2587,11 @@ int security_key_getsecurity(struct key *key, char **_buffer)
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#ifdef CONFIG_AUDIT
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#ifdef CONFIG_AUDIT
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int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule)
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int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule,
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gfp_t gfp)
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{
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{
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return call_int_hook(audit_rule_init, 0, field, op, rulestr, lsmrule);
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return call_int_hook(audit_rule_init, 0, field, op, rulestr, lsmrule,
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gfp);
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}
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}
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int security_audit_rule_known(struct audit_krule *krule)
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int security_audit_rule_known(struct audit_krule *krule)
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@ -18,12 +18,14 @@
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* @op: the operater the rule uses
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* @op: the operater the rule uses
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* @rulestr: the text "target" of the rule
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* @rulestr: the text "target" of the rule
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* @rule: pointer to the new rule structure returned via this
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* @rule: pointer to the new rule structure returned via this
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* @gfp: GFP flag used for kmalloc
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*
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*
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* Returns 0 if successful, -errno if not. On success, the rule structure
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* Returns 0 if successful, -errno if not. On success, the rule structure
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* will be allocated internally. The caller must free this structure with
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* will be allocated internally. The caller must free this structure with
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* selinux_audit_rule_free() after use.
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* selinux_audit_rule_free() after use.
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*/
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*/
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int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **rule);
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int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **rule,
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gfp_t gfp);
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/**
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/**
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* selinux_audit_rule_free - free an selinux audit rule structure.
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* selinux_audit_rule_free - free an selinux audit rule structure.
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@ -3560,7 +3560,8 @@ void selinux_audit_rule_free(void *vrule)
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}
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}
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}
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}
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int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
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int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule,
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gfp_t gfp)
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{
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{
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struct selinux_state *state = &selinux_state;
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struct selinux_state *state = &selinux_state;
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struct selinux_policy *policy;
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struct selinux_policy *policy;
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@ -3601,7 +3602,7 @@ int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
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return -EINVAL;
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return -EINVAL;
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}
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}
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tmprule = kzalloc(sizeof(struct selinux_audit_rule), GFP_KERNEL);
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tmprule = kzalloc(sizeof(struct selinux_audit_rule), gfp);
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if (!tmprule)
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if (!tmprule)
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return -ENOMEM;
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return -ENOMEM;
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@ -4487,11 +4487,13 @@ static int smack_post_notification(const struct cred *w_cred,
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* @op: required testing operator (=, !=, >, <, ...)
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* @op: required testing operator (=, !=, >, <, ...)
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* @rulestr: smack label to be audited
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* @rulestr: smack label to be audited
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* @vrule: pointer to save our own audit rule representation
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* @vrule: pointer to save our own audit rule representation
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* @gfp: type of the memory for the allocation
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*
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*
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* Prepare to audit cases where (@field @op @rulestr) is true.
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* Prepare to audit cases where (@field @op @rulestr) is true.
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* The label to be audited is created if necessay.
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* The label to be audited is created if necessay.
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*/
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*/
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static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
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static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule,
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gfp_t gfp)
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{
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{
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struct smack_known *skp;
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struct smack_known *skp;
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char **rule = (char **)vrule;
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char **rule = (char **)vrule;
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