From 6326948f940dc3f77066d5cdc44ba6afe67830c0 Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Wed, 29 Sep 2021 11:01:21 -0400 Subject: [PATCH] lsm: security_task_getsecid_subj() -> security_current_getsecid_subj() 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. Reviewed-by: Serge Hallyn Reviewed-by: Casey Schaufler Signed-off-by: Paul Moore --- 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 | 11 ++++++++++- 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, 49 insertions(+), 67 deletions(-) diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index df8de62f4710..ae2228f0711d 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -206,8 +206,7 @@ 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 d45b6f6e27fd..52c1990644b9 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -719,11 +719,9 @@ * @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 bbf44a466832..bb301963e333 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -418,7 +418,7 @@ 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); @@ -1119,7 +1119,7 @@ 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 d75acb014ccd..4173e771650c 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -1368,8 +1368,7 @@ 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 b517947bfa48..fce5d43a933f 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -666,7 +666,16 @@ 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 0d6585056f3d..4f0eecb67dde 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_current_label(); + *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 c88167a414b4..edb922b8bf4a 100644 --- a/security/security.c +++ b/security/security.c @@ -1808,12 +1808,12 @@ 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 62d30c0a30c2..726175254f60 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 */ @@ -4205,9 +4192,9 @@ 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) @@ -7159,7 +7146,7 @@ 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 efd35b07c7f8..14b279cc75c9 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -2067,15 +2067,14 @@ 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; } @@ -4807,7 +4806,7 @@ 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),