[PATCH] lsm: security_task_getsecid_subj() -> security_current_getsecid_subj()
Casey Schaufler
casey at schaufler-ca.com
Sat Nov 20 00:42:45 UTC 2021
On 11/19/2021 2:52 PM, Paul Moore wrote:
> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul at paul-moore.com> wrote:
>> The security_task_getsecid_subj() LSM hook invites misuse by allowing
>> callers to specify a task even though the hook is only safe when the
>> current task is referenced. Fix this by removing the task_struct
>> argument to the hook, requiring LSM implementations to use the
>> current task. While we are changing the hook declaration we also
>> rename the function to security_current_getsecid_subj() in an effort
>> to reinforce that the hook captures the subjective credentials of the
>> current task and not an arbitrary task on the system.
>>
>> Signed-off-by: Paul Moore <paul at paul-moore.com>
>> ---
>> include/linux/lsm_hook_defs.h | 3 +--
>> include/linux/lsm_hooks.h | 8 +++-----
>> include/linux/security.h | 4 ++--
>> kernel/audit.c | 4 ++--
>> kernel/auditfilter.c | 3 +--
>> kernel/auditsc.c | 10 +++++++++-
>> net/netlabel/netlabel_unlabeled.c | 2 +-
>> net/netlabel/netlabel_user.h | 2 +-
>> security/apparmor/lsm.c | 13 ++++++++++---
>> security/integrity/ima/ima_appraise.c | 2 +-
>> security/integrity/ima/ima_main.c | 14 +++++++-------
>> security/security.c | 6 +++---
>> security/selinux/hooks.c | 19 +++----------------
>> security/smack/smack.h | 16 ----------------
>> security/smack/smack_lsm.c | 9 ++++-----
>> 15 files changed, 48 insertions(+), 67 deletions(-)
> I never saw any comments, positive or negative, on this patch so I'll
> plan on merging it early next week. If you've got objections, now is
> the time to speak up.
It's OK by me.
Reviewed-by: Casey Schaufler <casey at schaufler-ca.com>
>
>> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
>> index 2adeea44c0d5..8d04b18155a3 100644
>> --- a/include/linux/lsm_hook_defs.h
>> +++ b/include/linux/lsm_hook_defs.h
>> @@ -205,8 +205,7 @@ LSM_HOOK(int, 0, task_fix_setgid, struct cred *new, const struct cred * old,
>> LSM_HOOK(int, 0, task_setpgid, struct task_struct *p, pid_t pgid)
>> LSM_HOOK(int, 0, task_getpgid, struct task_struct *p)
>> LSM_HOOK(int, 0, task_getsid, struct task_struct *p)
>> -LSM_HOOK(void, LSM_RET_VOID, task_getsecid_subj,
>> - struct task_struct *p, u32 *secid)
>> +LSM_HOOK(void, LSM_RET_VOID, current_getsecid_subj, u32 *secid)
>> LSM_HOOK(void, LSM_RET_VOID, task_getsecid_obj,
>> struct task_struct *p, u32 *secid)
>> LSM_HOOK(int, 0, task_setnice, struct task_struct *p, int nice)
>> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
>> index 5c4c5c0602cb..9f5b93011ecb 100644
>> --- a/include/linux/lsm_hooks.h
>> +++ b/include/linux/lsm_hooks.h
>> @@ -716,11 +716,9 @@
>> * @p.
>> * @p contains the task_struct for the process.
>> * Return 0 if permission is granted.
>> - * @task_getsecid_subj:
>> - * Retrieve the subjective security identifier of the task_struct in @p
>> - * and return it in @secid. Special care must be taken to ensure that @p
>> - * is the either the "current" task, or the caller has exclusive access
>> - * to @p.
>> + * @current_getsecid_subj:
>> + * Retrieve the subjective security identifier of the current task and
>> + * return it in @secid.
>> * In case of failure, @secid will be set to zero.
>> * @task_getsecid_obj:
>> * Retrieve the objective security identifier of the task_struct in @p
>> diff --git a/include/linux/security.h b/include/linux/security.h
>> index 5b7288521300..24190cf61858 100644
>> --- a/include/linux/security.h
>> +++ b/include/linux/security.h
>> @@ -417,7 +417,7 @@ int security_task_fix_setgid(struct cred *new, const struct cred *old,
>> int security_task_setpgid(struct task_struct *p, pid_t pgid);
>> int security_task_getpgid(struct task_struct *p);
>> int security_task_getsid(struct task_struct *p);
>> -void security_task_getsecid_subj(struct task_struct *p, u32 *secid);
>> +void security_current_getsecid_subj(u32 *secid);
>> void security_task_getsecid_obj(struct task_struct *p, u32 *secid);
>> int security_task_setnice(struct task_struct *p, int nice);
>> int security_task_setioprio(struct task_struct *p, int ioprio);
>> @@ -1112,7 +1112,7 @@ static inline int security_task_getsid(struct task_struct *p)
>> return 0;
>> }
>>
>> -static inline void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
>> +static inline void security_current_getsecid_subj(u32 *secid)
>> {
>> *secid = 0;
>> }
>> diff --git a/kernel/audit.c b/kernel/audit.c
>> index 121d37e700a6..d4084751cfe6 100644
>> --- a/kernel/audit.c
>> +++ b/kernel/audit.c
>> @@ -2132,7 +2132,7 @@ int audit_log_task_context(struct audit_buffer *ab)
>> int error;
>> u32 sid;
>>
>> - security_task_getsecid_subj(current, &sid);
>> + security_current_getsecid_subj(&sid);
>> if (!sid)
>> return 0;
>>
>> @@ -2353,7 +2353,7 @@ int audit_signal_info(int sig, struct task_struct *t)
>> audit_sig_uid = auid;
>> else
>> audit_sig_uid = uid;
>> - security_task_getsecid_subj(current, &audit_sig_sid);
>> + security_current_getsecid_subj(&audit_sig_sid);
>> }
>>
>> return audit_signal_info_syscall(t);
>> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
>> index db2c6b59dfc3..f4ebd2f1cfca 100644
>> --- a/kernel/auditfilter.c
>> +++ b/kernel/auditfilter.c
>> @@ -1359,8 +1359,7 @@ int audit_filter(int msgtype, unsigned int listtype)
>> case AUDIT_SUBJ_SEN:
>> case AUDIT_SUBJ_CLR:
>> if (f->lsm_rule) {
>> - security_task_getsecid_subj(current,
>> - &sid);
>> + security_current_getsecid_subj(&sid);
>> result = security_audit_rule_match(sid,
>> f->type, f->op, f->lsm_rule);
>> }
>> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
>> index 8dd73a64f921..e0987ee71b8f 100644
>> --- a/kernel/auditsc.c
>> +++ b/kernel/auditsc.c
>> @@ -673,7 +673,15 @@ static int audit_filter_rules(struct task_struct *tsk,
>> logged upon error */
>> if (f->lsm_rule) {
>> if (need_sid) {
>> - security_task_getsecid_subj(tsk, &sid);
>> + /* @tsk should always be equal to
>> + * @current with the exception of
>> + * fork()/copy_process() in which case
>> + * the new @tsk creds are still a dup
>> + * of @current's creds so we can still
>> + * use security_current_getsecid_subj()
>> + * here even though it always refs
>> + * @current's creds */
>> + security_current_getsecid_subj(&sid);
>> need_sid = 0;
>> }
>> result = security_audit_rule_match(sid, f->type,
>> diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
>> index 566ba4397ee4..8490e46359ae 100644
>> --- a/net/netlabel/netlabel_unlabeled.c
>> +++ b/net/netlabel/netlabel_unlabeled.c
>> @@ -1537,7 +1537,7 @@ int __init netlbl_unlabel_defconf(void)
>> /* Only the kernel is allowed to call this function and the only time
>> * it is called is at bootup before the audit subsystem is reporting
>> * messages so don't worry to much about these values. */
>> - security_task_getsecid_subj(current, &audit_info.secid);
>> + security_current_getsecid_subj(&audit_info.secid);
>> audit_info.loginuid = GLOBAL_ROOT_UID;
>> audit_info.sessionid = 0;
>>
>> diff --git a/net/netlabel/netlabel_user.h b/net/netlabel/netlabel_user.h
>> index 6190cbf94bf0..d6c5b31eb4eb 100644
>> --- a/net/netlabel/netlabel_user.h
>> +++ b/net/netlabel/netlabel_user.h
>> @@ -32,7 +32,7 @@
>> */
>> static inline void netlbl_netlink_auditinfo(struct netlbl_audit *audit_info)
>> {
>> - security_task_getsecid_subj(current, &audit_info->secid);
>> + security_current_getsecid_subj(&audit_info->secid);
>> audit_info->loginuid = audit_get_loginuid(current);
>> audit_info->sessionid = audit_get_sessionid(current);
>> }
>> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
>> index f72406fe1bf2..fc21190c4f4f 100644
>> --- a/security/apparmor/lsm.c
>> +++ b/security/apparmor/lsm.c
>> @@ -728,7 +728,14 @@ static void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
>> return;
>> }
>>
>> -static void apparmor_task_getsecid(struct task_struct *p, u32 *secid)
>> +static void apparmor_current_getsecid_subj(u32 *secid)
>> +{
>> + struct aa_label *label = aa_get_task_label(current);
>> + *secid = label->secid;
>> + aa_put_label(label);
>> +}
>> +
>> +static void apparmor_task_getsecid_obj(struct task_struct *p, u32 *secid)
>> {
>> struct aa_label *label = aa_get_task_label(p);
>> *secid = label->secid;
>> @@ -1252,8 +1259,8 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
>>
>> LSM_HOOK_INIT(task_free, apparmor_task_free),
>> LSM_HOOK_INIT(task_alloc, apparmor_task_alloc),
>> - LSM_HOOK_INIT(task_getsecid_subj, apparmor_task_getsecid),
>> - LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid),
>> + LSM_HOOK_INIT(current_getsecid_subj, apparmor_current_getsecid_subj),
>> + LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid_obj),
>> LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
>> LSM_HOOK_INIT(task_kill, apparmor_task_kill),
>>
>> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
>> index dbba51583e7c..17232bbfb9f9 100644
>> --- a/security/integrity/ima/ima_appraise.c
>> +++ b/security/integrity/ima/ima_appraise.c
>> @@ -76,7 +76,7 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
>> if (!ima_appraise)
>> return 0;
>>
>> - security_task_getsecid_subj(current, &secid);
>> + security_current_getsecid_subj(&secid);
>> return ima_match_policy(mnt_userns, inode, current_cred(), secid,
>> func, mask, IMA_APPRAISE | IMA_HASH, NULL,
>> NULL, NULL, NULL);
>> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
>> index 465865412100..8c6e4514d494 100644
>> --- a/security/integrity/ima/ima_main.c
>> +++ b/security/integrity/ima/ima_main.c
>> @@ -408,7 +408,7 @@ int ima_file_mmap(struct file *file, unsigned long prot)
>> u32 secid;
>>
>> if (file && (prot & PROT_EXEC)) {
>> - security_task_getsecid_subj(current, &secid);
>> + security_current_getsecid_subj(&secid);
>> return process_measurement(file, current_cred(), secid, NULL,
>> 0, MAY_EXEC, MMAP_CHECK);
>> }
>> @@ -446,7 +446,7 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
>> !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
>> return 0;
>>
>> - security_task_getsecid_subj(current, &secid);
>> + security_current_getsecid_subj(&secid);
>> inode = file_inode(vma->vm_file);
>> action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
>> current_cred(), secid, MAY_EXEC, MMAP_CHECK,
>> @@ -487,7 +487,7 @@ int ima_bprm_check(struct linux_binprm *bprm)
>> int ret;
>> u32 secid;
>>
>> - security_task_getsecid_subj(current, &secid);
>> + security_current_getsecid_subj(&secid);
>> ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
>> MAY_EXEC, BPRM_CHECK);
>> if (ret)
>> @@ -512,7 +512,7 @@ int ima_file_check(struct file *file, int mask)
>> {
>> u32 secid;
>>
>> - security_task_getsecid_subj(current, &secid);
>> + security_current_getsecid_subj(&secid);
>> return process_measurement(file, current_cred(), secid, NULL, 0,
>> mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
>> MAY_APPEND), FILE_CHECK);
>> @@ -709,7 +709,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
>>
>> /* Read entire file for all partial reads. */
>> func = read_idmap[read_id] ?: FILE_CHECK;
>> - security_task_getsecid_subj(current, &secid);
>> + security_current_getsecid_subj(&secid);
>> return process_measurement(file, current_cred(), secid, NULL,
>> 0, MAY_READ, func);
>> }
>> @@ -752,7 +752,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
>> }
>>
>> func = read_idmap[read_id] ?: FILE_CHECK;
>> - security_task_getsecid_subj(current, &secid);
>> + security_current_getsecid_subj(&secid);
>> return process_measurement(file, current_cred(), secid, buf, size,
>> MAY_READ, func);
>> }
>> @@ -905,7 +905,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
>> * buffer measurements.
>> */
>> if (func) {
>> - security_task_getsecid_subj(current, &secid);
>> + security_current_getsecid_subj(&secid);
>> action = ima_get_action(mnt_userns, inode, current_cred(),
>> secid, 0, func, &pcr, &template,
>> func_data, NULL);
>> diff --git a/security/security.c b/security/security.c
>> index 9ffa9e9c5c55..827bd161f8b0 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -1807,12 +1807,12 @@ int security_task_getsid(struct task_struct *p)
>> return call_int_hook(task_getsid, 0, p);
>> }
>>
>> -void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
>> +void security_current_getsecid_subj(u32 *secid)
>> {
>> *secid = 0;
>> - call_void_hook(task_getsecid_subj, p, secid);
>> + call_void_hook(current_getsecid_subj, secid);
>> }
>> -EXPORT_SYMBOL(security_task_getsecid_subj);
>> +EXPORT_SYMBOL(security_current_getsecid_subj);
>>
>> void security_task_getsecid_obj(struct task_struct *p, u32 *secid)
>> {
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index e7ebd45ca345..5c766b901f66 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -229,19 +229,6 @@ static inline u32 cred_sid(const struct cred *cred)
>> return tsec->sid;
>> }
>>
>> -/*
>> - * get the subjective security ID of a task
>> - */
>> -static inline u32 task_sid_subj(const struct task_struct *task)
>> -{
>> - u32 sid;
>> -
>> - rcu_read_lock();
>> - sid = cred_sid(rcu_dereference(task->cred));
>> - rcu_read_unlock();
>> - return sid;
>> -}
>> -
>> /*
>> * get the objective security ID of a task
>> */
>> @@ -4222,9 +4209,9 @@ static int selinux_task_getsid(struct task_struct *p)
>> PROCESS__GETSESSION, NULL);
>> }
>>
>> -static void selinux_task_getsecid_subj(struct task_struct *p, u32 *secid)
>> +static void selinux_current_getsecid_subj(u32 *secid)
>> {
>> - *secid = task_sid_subj(p);
>> + *secid = current_sid();
>> }
>>
>> static void selinux_task_getsecid_obj(struct task_struct *p, u32 *secid)
>> @@ -7221,7 +7208,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>> LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
>> LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),
>> LSM_HOOK_INIT(task_getsid, selinux_task_getsid),
>> - LSM_HOOK_INIT(task_getsecid_subj, selinux_task_getsecid_subj),
>> + LSM_HOOK_INIT(current_getsecid_subj, selinux_current_getsecid_subj),
>> LSM_HOOK_INIT(task_getsecid_obj, selinux_task_getsecid_obj),
>> LSM_HOOK_INIT(task_setnice, selinux_task_setnice),
>> LSM_HOOK_INIT(task_setioprio, selinux_task_setioprio),
>> diff --git a/security/smack/smack.h b/security/smack/smack.h
>> index 99c3422596ab..fc837dcebf96 100644
>> --- a/security/smack/smack.h
>> +++ b/security/smack/smack.h
>> @@ -389,22 +389,6 @@ static inline struct smack_known *smk_of_task(const struct task_smack *tsp)
>> return tsp->smk_task;
>> }
>>
>> -static inline struct smack_known *smk_of_task_struct_subj(
>> - const struct task_struct *t)
>> -{
>> - struct smack_known *skp;
>> - const struct cred *cred;
>> -
>> - rcu_read_lock();
>> -
>> - cred = rcu_dereference(t->cred);
>> - skp = smk_of_task(smack_cred(cred));
>> -
>> - rcu_read_unlock();
>> -
>> - return skp;
>> -}
>> -
>> static inline struct smack_known *smk_of_task_struct_obj(
>> const struct task_struct *t)
>> {
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index 21a0e7c3b8de..40e1d764e616 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -2061,15 +2061,14 @@ static int smack_task_getsid(struct task_struct *p)
>> }
>>
>> /**
>> - * smack_task_getsecid_subj - get the subjective secid of the task
>> - * @p: the task
>> + * smack_current_getsecid_subj - get the subjective secid of the current task
>> * @secid: where to put the result
>> *
>> * Sets the secid to contain a u32 version of the task's subjective smack label.
>> */
>> -static void smack_task_getsecid_subj(struct task_struct *p, u32 *secid)
>> +static void smack_current_getsecid_subj(u32 *secid)
>> {
>> - struct smack_known *skp = smk_of_task_struct_subj(p);
>> + struct smack_known *skp = smk_of_current();
>>
>> *secid = skp->smk_secid;
>> }
>> @@ -4756,7 +4755,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
>> LSM_HOOK_INIT(task_setpgid, smack_task_setpgid),
>> LSM_HOOK_INIT(task_getpgid, smack_task_getpgid),
>> LSM_HOOK_INIT(task_getsid, smack_task_getsid),
>> - LSM_HOOK_INIT(task_getsecid_subj, smack_task_getsecid_subj),
>> + LSM_HOOK_INIT(current_getsecid_subj, smack_current_getsecid_subj),
>> LSM_HOOK_INIT(task_getsecid_obj, smack_task_getsecid_obj),
>> LSM_HOOK_INIT(task_setnice, smack_task_setnice),
>> LSM_HOOK_INIT(task_setioprio, smack_task_setioprio),
>>
>
More information about the Linux-security-module-archive
mailing list