| Message ID | 20240428091045.85513-1-guozihua@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] ima: Avoid blocking in RCU read-side critical section | expand |
On 4/28/2024 2:10 AM, GUO Zihua wrote: > A panic happens in ima_match_policy: You need to add linux-security-module@vger.kernel.org to your CC list. > > 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> > --- > > v2: > Changed the audit_rule_init security hook to accept a new GFP flag, as > per Stephen's suggestion. > > --- > include/linux/lsm_hook_defs.h | 2 +- > include/linux/security.h | 5 +++-- > kernel/auditfilter.c | 5 +++-- > security/apparmor/audit.c | 6 +++--- > security/apparmor/include/audit.h | 2 +- > security/integrity/ima/ima_policy.c | 8 +++++--- > security/security.c | 6 ++++-- > security/selinux/include/audit.h | 4 +++- > security/selinux/ss/services.c | 5 +++-- > security/smack/smack_lsm.c | 3 ++- > 10 files changed, 28 insertions(+), 18 deletions(-) > > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index 334e00efbde4..7e539f6f8c67 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -412,7 +412,7 @@ LSM_HOOK(void, LSM_RET_VOID, key_post_create_or_update, struct key *keyring, > > #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) > diff --git a/include/linux/security.h b/include/linux/security.h > index 41a8f667bdfa..5122e3ad83b1 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -2048,7 +2048,8 @@ static inline void security_key_post_create_or_update(struct key *keyring, > > #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); > @@ -2056,7 +2057,7 @@ 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; > } > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c > index be8c680121e4..d6ef4f4f9cba 100644 > --- a/kernel/auditfilter.c > +++ b/kernel/auditfilter.c > @@ -529,7 +529,8 @@ 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) { > @@ -799,7 +800,7 @@ 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) { > 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_policy.c b/security/integrity/ima/ima_policy.c > index c0556907c2e6..216ffe388ce5 100644 > --- a/security/integrity/ima/ima_policy.c > +++ b/security/integrity/ima/ima_policy.c > @@ -410,7 +410,7 @@ 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_ATOMIC); > if (!nentry) > return NULL; > > @@ -425,7 +425,8 @@ 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_ATOMIC); > if (!nentry->lsm[i].rule) > pr_warn("rule for LSM \'%s\' is undefined\n", > nentry->lsm[i].args_p); > @@ -1140,7 +1141,8 @@ 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 0a9a0ac3f266..4fd3c839353e 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -5331,15 +5331,17 @@ 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 e88b1b6c4adb..ded250e525e9 100644 > --- a/security/selinux/ss/services.c > +++ b/security/selinux/ss/services.c > @@ -3508,7 +3508,8 @@ 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; > @@ -3549,7 +3550,7 @@ 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 146667937811..a4943628d75a 100644 > --- a/security/smack/smack_lsm.c > +++ b/security/smack/smack_lsm.c > @@ -4696,7 +4696,8 @@ static int smack_post_notification(const struct cred *w_cred, > * 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;
Hi Scott, On Sun, 2024-04-28 at 09:10 +0000, GUO Zihua wrote: > diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c > index c0556907c2e6..216ffe388ce5 100644 > --- a/security/integrity/ima/ima_policy.c > +++ b/security/integrity/ima/ima_policy.c > @@ -410,7 +410,7 @@ 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_ATOMIC); > if (!nentry) > return NULL; > > @@ -425,7 +425,8 @@ 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_ATOMIC); > if (!nentry->lsm[i].rule) > pr_warn("rule for LSM \'%s\' is undefined\n", > nentry->lsm[i].args_p); If only the call to ima_lsm_copy_rule() in ima_match_rules() needs to be GFP_ATOMIC, then pass the gfp type. thanks, Mimi > @@ -1140,7 +1141,8 @@ 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/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 334e00efbde4..7e539f6f8c67 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -412,7 +412,7 @@ LSM_HOOK(void, LSM_RET_VOID, key_post_create_or_update, struct key *keyring, #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) diff --git a/include/linux/security.h b/include/linux/security.h index 41a8f667bdfa..5122e3ad83b1 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -2048,7 +2048,8 @@ static inline void security_key_post_create_or_update(struct key *keyring, #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); @@ -2056,7 +2057,7 @@ 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; } diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index be8c680121e4..d6ef4f4f9cba 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -529,7 +529,8 @@ 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) { @@ -799,7 +800,7 @@ 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) { 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_policy.c b/security/integrity/ima/ima_policy.c index c0556907c2e6..216ffe388ce5 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -410,7 +410,7 @@ 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_ATOMIC); if (!nentry) return NULL; @@ -425,7 +425,8 @@ 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_ATOMIC); if (!nentry->lsm[i].rule) pr_warn("rule for LSM \'%s\' is undefined\n", nentry->lsm[i].args_p); @@ -1140,7 +1141,8 @@ 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 0a9a0ac3f266..4fd3c839353e 100644 --- a/security/security.c +++ b/security/security.c @@ -5331,15 +5331,17 @@ 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 e88b1b6c4adb..ded250e525e9 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -3508,7 +3508,8 @@ 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; @@ -3549,7 +3550,7 @@ 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 146667937811..a4943628d75a 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -4696,7 +4696,8 @@ static int smack_post_notification(const struct cred *w_cred, * 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;
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> --- v2: Changed the audit_rule_init security hook to accept a new GFP flag, as per Stephen's suggestion. --- include/linux/lsm_hook_defs.h | 2 +- include/linux/security.h | 5 +++-- kernel/auditfilter.c | 5 +++-- security/apparmor/audit.c | 6 +++--- security/apparmor/include/audit.h | 2 +- security/integrity/ima/ima_policy.c | 8 +++++--- security/security.c | 6 ++++-- security/selinux/include/audit.h | 4 +++- security/selinux/ss/services.c | 5 +++-- security/smack/smack_lsm.c | 3 ++- 10 files changed, 28 insertions(+), 18 deletions(-)