[PATCH v33 11/29] LSM: Use lsmblob in security_current_getsecid

Casey Schaufler
2022-03-10T23:52:14Z

Change the security_current_getsecid_subj() and
security_task_getsecid_obj() interfaces to fill in
a lsmblob structure instead of a u32 secid in support of
LSM stacking. Audit interfaces will need to collect all
possible secids for possible reporting.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: linux-integrity@vger.kernel.org
Cc: linux-audit@redhat.com
Cc: netdev@vger.kernel.org
---
drivers/android/binder.c | 6 +--
include/linux/security.h | 13 ++++---
kernel/audit.c | 16 +++-----
kernel/auditfilter.c | 4 +-
kernel/auditsc.c | 25 ++++++------
net/netlabel/netlabel_unlabeled.c | 5 ++-
net/netlabel/netlabel_user.h | 6 ++-
security/integrity/ima/ima_appraise.c | 12 +++---
security/integrity/ima/ima_main.c | 55 +++++++++++++++------------
security/security.c | 25 +++++++++---
10 files changed, 95 insertions(+), 72 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 381a4fddd4a5..bae8440ffc73 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2980,16 +2980,16 @@ static void binder_transaction(struct binder_proc *proc,
t->priority = task_nice(current);

if (target_node && target_node->txn_security_ctx) {
- u32 secid;
struct lsmblob blob;
size_t added_size;
+ u32 secid;

security_cred_getsecid(proc->cred, &secid);
/*
- * Later in this patch set security_task_getsecid() will
+ * Later in this patch set security_cred_getsecid() will
* provide a lsmblob instead of a secid. lsmblob_init
* is used to ensure that all the secids in the lsmblob
- * get the value returned from security_task_getsecid(),
+ * get the value returned from security_cred_getsecid(),
* which means that the one expected by
* security_secid_to_secctx() will be set.
*/
diff --git a/include/linux/security.h b/include/linux/security.h
index 1814516509ec..5f20c0c68f67 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -502,8 +502,8 @@ 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_current_getsecid_subj(u32 *secid);
-void security_task_getsecid_obj(struct task_struct *p, u32 *secid);
+void security_current_getsecid_subj(struct lsmblob *blob);
+void security_task_getsecid_obj(struct task_struct *p, struct lsmblob *blob);
int security_task_setnice(struct task_struct *p, int nice);
int security_task_setioprio(struct task_struct *p, int ioprio);
int security_task_getioprio(struct task_struct *p);
@@ -1199,14 +1199,15 @@ static inline int security_task_getsid(struct task_struct *p)
return 0;
}

-static inline void security_current_getsecid_subj(u32 *secid)
+static inline void security_current_getsecid_subj(struct lsmblob *blob)
{
- *secid = 0;
+ lsmblob_init(blob, 0);
}

-static inline void security_task_getsecid_obj(struct task_struct *p, u32 *secid)
+static inline void security_task_getsecid_obj(struct task_struct *p,
+ struct lsmblob *blob)
{
- *secid = 0;
+ lsmblob_init(blob, 0);
}

static inline int security_task_setnice(struct task_struct *p, int nice)
diff --git a/kernel/audit.c b/kernel/audit.c
index 40d8cb824eae..17ac6e74b5bd 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2154,19 +2154,12 @@ int audit_log_task_context(struct audit_buffer *ab)
char *ctx = NULL;
unsigned len;
int error;
- u32 sid;
struct lsmblob blob;

- security_current_getsecid_subj(&sid);
- if (!sid)
+ security_current_getsecid_subj(&blob);
+ if (!lsmblob_is_set(&blob))
return 0;

- /*
- * lsmblob_init sets all values in the lsmblob to sid.
- * This is temporary until security_task_getsecid is converted
- * to use a lsmblob, which happens later in this patch set.
- */
- lsmblob_init(&blob, sid);
error = security_secid_to_secctx(&blob, &ctx, &len);

if (error) {
@@ -2375,6 +2368,7 @@ int audit_set_loginuid(kuid_t loginuid)
int audit_signal_info(int sig, struct task_struct *t)
{
kuid_t uid = current_uid(), auid;
+ struct lsmblob blob;

if (auditd_test_task(t) &&
(sig == SIGTERM || sig == SIGHUP ||
@@ -2385,7 +2379,9 @@ int audit_signal_info(int sig, struct task_struct *t)
audit_sig_uid = auid;
else
audit_sig_uid = uid;
- security_current_getsecid_subj(&audit_sig_sid);
+ security_current_getsecid_subj(&blob);
+ /* scaffolding until audit_sig_sid is converted */
+ audit_sig_sid = blob.secid[0];
}

return audit_signal_info_syscall(t);
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 15cd4fe35e9c..39ded5cb2429 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1339,7 +1339,6 @@ int audit_filter(int msgtype, unsigned int listtype)
struct audit_field *f = &e->rule.fields[i];
struct lsmblob blob;
pid_t pid;
- u32 sid;

switch (f->type) {
case AUDIT_PID:
@@ -1369,8 +1368,7 @@ int audit_filter(int msgtype, unsigned int listtype)
case AUDIT_SUBJ_SEN:
case AUDIT_SUBJ_CLR:
if (f->lsm_str) {
- security_current_getsecid_subj(&sid);
- lsmblob_init(&blob, sid);
+ security_current_getsecid_subj(&blob);
result = security_audit_rule_match(
&blob, f->type, f->op,
&f->lsm_rules);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 598e0de45b04..2570bf5979e0 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -467,7 +467,6 @@ static int audit_filter_rules(struct task_struct *tsk,
{
const struct cred *cred;
int i, need_sid = 1;
- u32 sid;
struct lsmblob blob;
unsigned int sessionid;

@@ -676,17 +675,9 @@ static int audit_filter_rules(struct task_struct *tsk,
* here even though it always refs
* @current's creds
*/
- security_current_getsecid_subj(&sid);
+ security_current_getsecid_subj(&blob);
need_sid = 0;
}
- /*
- * lsmblob_init sets all values in the lsmblob
- * to sid. This is temporary until
- * security_task_getsecid() is converted to
- * provide a lsmblob, which happens later in
- * this patch set.
- */
- lsmblob_init(&blob, sid);
result = security_audit_rule_match(&blob,
f->type, f->op,
&f->lsm_rules);
@@ -2712,12 +2703,15 @@ int __audit_sockaddr(int len, void *a)
void __audit_ptrace(struct task_struct *t)
{
struct audit_context *context = audit_context();
+ struct lsmblob blob;

context->target_pid = task_tgid_nr(t);
context->target_auid = audit_get_loginuid(t);
context->target_uid = task_uid(t);
context->target_sessionid = audit_get_sessionid(t);
- security_task_getsecid_obj(t, &context->target_sid);
+ security_task_getsecid_obj(t, &blob);
+ /* scaffolding - until target_sid is converted */
+ context->target_sid = blob.secid[0];
memcpy(context->target_comm, t->comm, TASK_COMM_LEN);
}

@@ -2733,6 +2727,7 @@ int audit_signal_info_syscall(struct task_struct *t)
struct audit_aux_data_pids *axp;
struct audit_context *ctx = audit_context();
kuid_t t_uid = task_uid(t);
+ struct lsmblob blob;

if (!audit_signals || audit_dummy_context())
return 0;
@@ -2744,7 +2739,9 @@ int audit_signal_info_syscall(struct task_struct *t)
ctx->target_auid = audit_get_loginuid(t);
ctx->target_uid = t_uid;
ctx->target_sessionid = audit_get_sessionid(t);
- security_task_getsecid_obj(t, &ctx->target_sid);
+ security_task_getsecid_obj(t, &blob);
+ /* scaffolding until target_sid is converted */
+ ctx->target_sid = blob.secid[0];
memcpy(ctx->target_comm, t->comm, TASK_COMM_LEN);
return 0;
}
@@ -2765,7 +2762,9 @@ int audit_signal_info_syscall(struct task_struct *t)
axp->target_auid[axp->pid_count] = audit_get_loginuid(t);
axp->target_uid[axp->pid_count] = t_uid;
axp->target_sessionid[axp->pid_count] = audit_get_sessionid(t);
- security_task_getsecid_obj(t, &axp->target_sid[axp->pid_count]);
+ security_task_getsecid_obj(t, &blob);
+ /* scaffolding until target_sid is converted */
+ axp->target_sid[axp->pid_count] = blob.secid[0];
memcpy(axp->target_comm[axp->pid_count], t->comm, TASK_COMM_LEN);
axp->pid_count++;

diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index 0a99663e6edb..c86df6ead742 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -1562,11 +1562,14 @@ int __init netlbl_unlabel_defconf(void)
int ret_val;
struct netlbl_dom_map *entry;
struct netlbl_audit audit_info;
+ struct lsmblob blob;

/* 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_current_getsecid_subj(&audit_info.secid);
+ security_current_getsecid_subj(&blob);
+ /* scaffolding until audit_info.secid is converted */
+ audit_info.secid = blob.secid[0];
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 d6c5b31eb4eb..3d5610ed5f0e 100644
--- a/net/netlabel/netlabel_user.h
+++ b/net/netlabel/netlabel_user.h
@@ -32,7 +32,11 @@
*/
static inline void netlbl_netlink_auditinfo(struct netlbl_audit *audit_info)
{
- security_current_getsecid_subj(&audit_info->secid);
+ struct lsmblob blob;
+
+ security_current_getsecid_subj(&blob);
+ /* scaffolding until secid is converted */
+ audit_info->secid = blob.secid[0];
audit_info->loginuid = audit_get_loginuid(current);
audit_info->sessionid = audit_get_sessionid(current);
}
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 17232bbfb9f9..217d20c60e1d 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -71,15 +71,17 @@ bool is_ima_appraise_enabled(void)
int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
int mask, enum ima_hooks func)
{
- u32 secid;
+ struct lsmblob blob;

if (!ima_appraise)
return 0;

- 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);
+ security_current_getsecid_subj(&blob);
+ /* scaffolding the .secid[0] */
+ return ima_match_policy(mnt_userns, inode, current_cred(),
+ blob.secid[0], func, mask,
+ IMA_APPRAISE | IMA_HASH, NULL, NULL, NULL,
+ NULL);
}

static int ima_fix_xattr(struct dentry *dentry,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 8c6e4514d494..6abbaa97bbeb 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -405,12 +405,13 @@ static int process_measurement(struct file *file, const struct cred *cred,
*/
int ima_file_mmap(struct file *file, unsigned long prot)
{
- u32 secid;
+ struct lsmblob blob;

if (file && (prot & PROT_EXEC)) {
- security_current_getsecid_subj(&secid);
- return process_measurement(file, current_cred(), secid, NULL,
- 0, MAY_EXEC, MMAP_CHECK);
+ security_current_getsecid_subj(&blob);
+ /* scaffolding - until process_measurement changes */
+ return process_measurement(file, current_cred(), blob.secid[0],
+ NULL, 0, MAY_EXEC, MMAP_CHECK);
}

return 0;
@@ -436,9 +437,9 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
char *pathbuf = NULL;
const char *pathname = NULL;
struct inode *inode;
+ struct lsmblob blob;
int result = 0;
int action;
- u32 secid;
int pcr;

/* Is mprotect making an mmap'ed file executable? */
@@ -446,11 +447,11 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
!(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
return 0;

- security_current_getsecid_subj(&secid);
+ security_current_getsecid_subj(&blob);
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,
- &pcr, &template, NULL, NULL);
+ current_cred(), blob.secid[0], MAY_EXEC,
+ MMAP_CHECK, &pcr, &template, NULL, NULL);

/* Is the mmap'ed file in policy? */
if (!(action & (IMA_MEASURE | IMA_APPRAISE_SUBMASK)))
@@ -486,10 +487,12 @@ int ima_bprm_check(struct linux_binprm *bprm)
{
int ret;
u32 secid;
+ struct lsmblob blob;

- security_current_getsecid_subj(&secid);
- ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
- MAY_EXEC, BPRM_CHECK);
+ security_current_getsecid_subj(&blob);
+ /* scaffolding until process_measurement changes */
+ ret = process_measurement(bprm->file, current_cred(), blob.secid[0],
+ NULL, 0, MAY_EXEC, BPRM_CHECK);
if (ret)
return ret;

@@ -510,10 +513,11 @@ int ima_bprm_check(struct linux_binprm *bprm)
*/
int ima_file_check(struct file *file, int mask)
{
- u32 secid;
+ struct lsmblob blob;

- security_current_getsecid_subj(&secid);
- return process_measurement(file, current_cred(), secid, NULL, 0,
+ security_current_getsecid_subj(&blob);
+ /* scaffolding until process_measurement changes */
+ return process_measurement(file, current_cred(), blob.secid[0], NULL, 0,
mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
MAY_APPEND), FILE_CHECK);
}
@@ -689,7 +693,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
bool contents)
{
enum ima_hooks func;
- u32 secid;
+ struct lsmblob blob;

/*
* Do devices using pre-allocated memory run the risk of the
@@ -709,8 +713,9 @@ 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_current_getsecid_subj(&secid);
- return process_measurement(file, current_cred(), secid, NULL,
+ security_current_getsecid_subj(&blob);
+ /* scaffolding - until process_measurement changes */
+ return process_measurement(file, current_cred(), blob.secid[0], NULL,
0, MAY_READ, func);
}

@@ -739,7 +744,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
enum kernel_read_file_id read_id)
{
enum ima_hooks func;
- u32 secid;
+ struct lsmblob blob;

/* permit signed certs */
if (!file && read_id == READING_X509_CERTIFICATE)
@@ -752,9 +757,10 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
}

func = read_idmap[read_id] ?: FILE_CHECK;
- security_current_getsecid_subj(&secid);
- return process_measurement(file, current_cred(), secid, buf, size,
- MAY_READ, func);
+ security_current_getsecid_subj(&blob);
+ /* scaffolding - until process_measurement changes */
+ return process_measurement(file, current_cred(), blob.secid[0], buf,
+ size, MAY_READ, func);
}

/**
@@ -882,7 +888,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
int digest_hash_len = hash_digest_size[ima_hash_algo];
int violation = 0;
int action = 0;
- u32 secid;
+ struct lsmblob blob;

if (digest && digest_len < digest_hash_len)
return -EINVAL;
@@ -905,9 +911,10 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
* buffer measurements.
*/
if (func) {
- security_current_getsecid_subj(&secid);
+ security_current_getsecid_subj(&blob);
+ /* scaffolding */
action = ima_get_action(mnt_userns, inode, current_cred(),
- secid, 0, func, &pcr, &template,
+ blob.secid[0], 0, func, &pcr, &template,
func_data, NULL);
if (!(action & IMA_MEASURE) && !digest)
return -ENOENT;
diff --git a/security/security.c b/security/security.c
index 815200684bcf..e33fa677181d 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1909,17 +1909,30 @@ int security_task_getsid(struct task_struct *p)
return call_int_hook(task_getsid, 0, p);
}

-void security_current_getsecid_subj(u32 *secid)
+void security_current_getsecid_subj(struct lsmblob *blob)
{
- *secid = 0;
- call_void_hook(current_getsecid_subj, secid);
+ struct security_hook_list *hp;
+
+ lsmblob_init(blob, 0);
+ hlist_for_each_entry(hp, &security_hook_heads.current_getsecid_subj,
+ list) {
+ if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
+ continue;
+ hp->hook.current_getsecid_subj(&blob->secid[hp->lsmid->slot]);
+ }
}
EXPORT_SYMBOL(security_current_getsecid_subj);

-void security_task_getsecid_obj(struct task_struct *p, u32 *secid)
+void security_task_getsecid_obj(struct task_struct *p, struct lsmblob *blob)
{
- *secid = 0;
- call_void_hook(task_getsecid_obj, p, secid);
+ struct security_hook_list *hp;
+
+ lsmblob_init(blob, 0);
+ hlist_for_each_entry(hp, &security_hook_heads.task_getsecid_obj, list) {
+ if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
+ continue;
+ hp->hook.task_getsecid_obj(p, &blob->secid[hp->lsmid->slot]);
+ }
}
EXPORT_SYMBOL(security_task_getsecid_obj);

--
2.31.1