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selinuxfs.c
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// SPDX-License-Identifier: GPL-2.0-only
/* Updated: Karl MacMillan <kmacmillan@tresys.com>
*
* Added conditional policy language extensions
*
* Updated: Hewlett-Packard <paul@paul-moore.com>
*
* Added support for the policy capability bitmap
*
* Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
* Copyright (C) 2003 - 2004 Tresys Technology, LLC
* Copyright (C) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
*/
#include <linux/kernel.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/mount.h>
#include <linux/mutex.h>
#include <linux/namei.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/security.h>
#include <linux/major.h>
#include <linux/seq_file.h>
#include <linux/percpu.h>
#include <linux/audit.h>
#include <linux/uaccess.h>
#include <linux/kobject.h>
#include <linux/ctype.h>
/* selinuxfs pseudo filesystem for exporting the security policy API.
Based on the proc code and the fs/nfsd/nfsctl.c code. */
#include "flask.h"
#include "avc.h"
#include "avc_ss.h"
#include "security.h"
#include "objsec.h"
#include "conditional.h"
#include "ima.h"
enum sel_inos {
SEL_ROOT_INO = 2,
SEL_LOAD, /* load policy */
SEL_ENFORCE, /* get or set enforcing status */
SEL_CONTEXT, /* validate context */
SEL_ACCESS, /* compute access decision */
SEL_CREATE, /* compute create labeling decision */
SEL_RELABEL, /* compute relabeling decision */
SEL_USER, /* compute reachable user contexts */
SEL_POLICYVERS, /* return policy version for this kernel */
SEL_COMMIT_BOOLS, /* commit new boolean values */
SEL_MLS, /* return if MLS policy is enabled */
SEL_DISABLE, /* disable SELinux until next reboot */
SEL_MEMBER, /* compute polyinstantiation membership decision */
SEL_CHECKREQPROT, /* check requested protection, not kernel-applied one */
SEL_COMPAT_NET, /* whether to use old compat network packet controls */
SEL_REJECT_UNKNOWN, /* export unknown reject handling to userspace */
SEL_DENY_UNKNOWN, /* export unknown deny handling to userspace */
SEL_STATUS, /* export current status using mmap() */
SEL_POLICY, /* allow userspace to read the in kernel policy */
SEL_VALIDATE_TRANS, /* compute validatetrans decision */
SEL_INO_NEXT, /* The next inode number to use */
};
struct selinux_fs_info {
struct dentry *bool_dir;
unsigned int bool_num;
char **bool_pending_names;
int *bool_pending_values;
struct dentry *class_dir;
unsigned long last_class_ino;
bool policy_opened;
struct dentry *policycap_dir;
unsigned long last_ino;
struct super_block *sb;
};
static int selinux_fs_info_create(struct super_block *sb)
{
struct selinux_fs_info *fsi;
fsi = kzalloc(sizeof(*fsi), GFP_KERNEL);
if (!fsi)
return -ENOMEM;
fsi->last_ino = SEL_INO_NEXT - 1;
fsi->sb = sb;
sb->s_fs_info = fsi;
return 0;
}
static void selinux_fs_info_free(struct super_block *sb)
{
struct selinux_fs_info *fsi = sb->s_fs_info;
unsigned int i;
if (fsi) {
for (i = 0; i < fsi->bool_num; i++)
kfree(fsi->bool_pending_names[i]);
kfree(fsi->bool_pending_names);
kfree(fsi->bool_pending_values);
}
kfree(sb->s_fs_info);
sb->s_fs_info = NULL;
}
#define SEL_INITCON_INO_OFFSET 0x01000000
#define SEL_BOOL_INO_OFFSET 0x02000000
#define SEL_CLASS_INO_OFFSET 0x04000000
#define SEL_POLICYCAP_INO_OFFSET 0x08000000
#define SEL_INO_MASK 0x00ffffff
#define BOOL_DIR_NAME "booleans"
#define CLASS_DIR_NAME "class"
#define POLICYCAP_DIR_NAME "policy_capabilities"
#define TMPBUFLEN 12
static ssize_t sel_read_enforce(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
char tmpbuf[TMPBUFLEN];
ssize_t length;
length = scnprintf(tmpbuf, TMPBUFLEN, "%d",
enforcing_enabled());
return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}
#ifdef CONFIG_SECURITY_SELINUX_DEVELOP
static ssize_t sel_write_enforce(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char *page = NULL;
ssize_t length;
int scan_value;
bool old_value, new_value;
if (count >= PAGE_SIZE)
return -ENOMEM;
/* No partial writes. */
if (*ppos != 0)
return -EINVAL;
page = memdup_user_nul(buf, count);
if (IS_ERR(page))
return PTR_ERR(page);
length = -EINVAL;
if (sscanf(page, "%d", &scan_value) != 1)
goto out;
new_value = !!scan_value;
old_value = enforcing_enabled();
if (new_value != old_value) {
length = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__SETENFORCE,
NULL);
if (length)
goto out;
audit_log(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS,
"enforcing=%d old_enforcing=%d auid=%u ses=%u"
" enabled=1 old-enabled=1 lsm=selinux res=1",
new_value, old_value,
from_kuid(&init_user_ns, audit_get_loginuid(current)),
audit_get_sessionid(current));
enforcing_set(new_value);
if (new_value)
avc_ss_reset(0);
selnl_notify_setenforce(new_value);
selinux_status_update_setenforce(new_value);
if (!new_value)
call_blocking_lsm_notifier(LSM_POLICY_CHANGE, NULL);
selinux_ima_measure_state();
}
length = count;
out:
kfree(page);
return length;
}
#else
#define sel_write_enforce NULL
#endif
static const struct file_operations sel_enforce_ops = {
.read = sel_read_enforce,
.write = sel_write_enforce,
.llseek = generic_file_llseek,
};
static ssize_t sel_read_handle_unknown(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
char tmpbuf[TMPBUFLEN];
ssize_t length;
ino_t ino = file_inode(filp)->i_ino;
int handle_unknown = (ino == SEL_REJECT_UNKNOWN) ?
security_get_reject_unknown() :
!security_get_allow_unknown();
length = scnprintf(tmpbuf, TMPBUFLEN, "%d", handle_unknown);
return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}
static const struct file_operations sel_handle_unknown_ops = {
.read = sel_read_handle_unknown,
.llseek = generic_file_llseek,
};
static int sel_open_handle_status(struct inode *inode, struct file *filp)
{
struct page *status = selinux_kernel_status_page();
if (!status)
return -ENOMEM;
filp->private_data = status;
return 0;
}
static ssize_t sel_read_handle_status(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
struct page *status = filp->private_data;
BUG_ON(!status);
return simple_read_from_buffer(buf, count, ppos,
page_address(status),
sizeof(struct selinux_kernel_status));
}
static int sel_mmap_handle_status(struct file *filp,
struct vm_area_struct *vma)
{
struct page *status = filp->private_data;
unsigned long size = vma->vm_end - vma->vm_start;
BUG_ON(!status);
/* only allows one page from the head */
if (vma->vm_pgoff > 0 || size != PAGE_SIZE)
return -EIO;
/* disallow writable mapping */
if (vma->vm_flags & VM_WRITE)
return -EPERM;
/* disallow mprotect() turns it into writable */
vm_flags_clear(vma, VM_MAYWRITE);
return remap_pfn_range(vma, vma->vm_start,
page_to_pfn(status),
size, vma->vm_page_prot);
}
static const struct file_operations sel_handle_status_ops = {
.open = sel_open_handle_status,
.read = sel_read_handle_status,
.mmap = sel_mmap_handle_status,
.llseek = generic_file_llseek,
};
static ssize_t sel_write_disable(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char *page;
ssize_t length;
int new_value;
if (count >= PAGE_SIZE)
return -ENOMEM;
/* No partial writes. */
if (*ppos != 0)
return -EINVAL;
page = memdup_user_nul(buf, count);
if (IS_ERR(page))
return PTR_ERR(page);
if (sscanf(page, "%d", &new_value) != 1) {
length = -EINVAL;
goto out;
}
length = count;
if (new_value) {
pr_err("SELinux: https://github.com/SELinuxProject/selinux-kernel/wiki/DEPRECATE-runtime-disable\n");
pr_err("SELinux: Runtime disable is not supported, use selinux=0 on the kernel cmdline.\n");
}
out:
kfree(page);
return length;
}
static const struct file_operations sel_disable_ops = {
.write = sel_write_disable,
.llseek = generic_file_llseek,
};
static ssize_t sel_read_policyvers(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
char tmpbuf[TMPBUFLEN];
ssize_t length;
length = scnprintf(tmpbuf, TMPBUFLEN, "%u", POLICYDB_VERSION_MAX);
return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}
static const struct file_operations sel_policyvers_ops = {
.read = sel_read_policyvers,
.llseek = generic_file_llseek,
};
/* declaration for sel_write_load */
static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_dir,
unsigned int *bool_num, char ***bool_pending_names,
int **bool_pending_values);
static int sel_make_classes(struct selinux_policy *newpolicy,
struct dentry *class_dir,
unsigned long *last_class_ino);
/* declaration for sel_make_class_dirs */
static struct dentry *sel_make_dir(struct dentry *dir, const char *name,
unsigned long *ino);
/* declaration for sel_make_policy_nodes */
static struct dentry *sel_make_swapover_dir(struct super_block *sb,
unsigned long *ino);
static ssize_t sel_read_mls(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
char tmpbuf[TMPBUFLEN];
ssize_t length;
length = scnprintf(tmpbuf, TMPBUFLEN, "%d",
security_mls_enabled());
return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}
static const struct file_operations sel_mls_ops = {
.read = sel_read_mls,
.llseek = generic_file_llseek,
};
struct policy_load_memory {
size_t len;
void *data;
};
static int sel_open_policy(struct inode *inode, struct file *filp)
{
struct selinux_fs_info *fsi = inode->i_sb->s_fs_info;
struct policy_load_memory *plm = NULL;
int rc;
BUG_ON(filp->private_data);
mutex_lock(&selinux_state.policy_mutex);
rc = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__READ_POLICY, NULL);
if (rc)
goto err;
rc = -EBUSY;
if (fsi->policy_opened)
goto err;
rc = -ENOMEM;
plm = kzalloc(sizeof(*plm), GFP_KERNEL);
if (!plm)
goto err;
rc = security_read_policy(&plm->data, &plm->len);
if (rc)
goto err;
if ((size_t)i_size_read(inode) != plm->len) {
inode_lock(inode);
i_size_write(inode, plm->len);
inode_unlock(inode);
}
fsi->policy_opened = 1;
filp->private_data = plm;
mutex_unlock(&selinux_state.policy_mutex);
return 0;
err:
mutex_unlock(&selinux_state.policy_mutex);
if (plm)
vfree(plm->data);
kfree(plm);
return rc;
}
static int sel_release_policy(struct inode *inode, struct file *filp)
{
struct selinux_fs_info *fsi = inode->i_sb->s_fs_info;
struct policy_load_memory *plm = filp->private_data;
BUG_ON(!plm);
fsi->policy_opened = 0;
vfree(plm->data);
kfree(plm);
return 0;
}
static ssize_t sel_read_policy(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
struct policy_load_memory *plm = filp->private_data;
int ret;
ret = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__READ_POLICY, NULL);
if (ret)
return ret;
return simple_read_from_buffer(buf, count, ppos, plm->data, plm->len);
}
static vm_fault_t sel_mmap_policy_fault(struct vm_fault *vmf)
{
struct policy_load_memory *plm = vmf->vma->vm_file->private_data;
unsigned long offset;
struct page *page;
if (vmf->flags & (FAULT_FLAG_MKWRITE | FAULT_FLAG_WRITE))
return VM_FAULT_SIGBUS;
offset = vmf->pgoff << PAGE_SHIFT;
if (offset >= roundup(plm->len, PAGE_SIZE))
return VM_FAULT_SIGBUS;
page = vmalloc_to_page(plm->data + offset);
get_page(page);
vmf->page = page;
return 0;
}
static const struct vm_operations_struct sel_mmap_policy_ops = {
.fault = sel_mmap_policy_fault,
.page_mkwrite = sel_mmap_policy_fault,
};
static int sel_mmap_policy(struct file *filp, struct vm_area_struct *vma)
{
if (vma->vm_flags & VM_SHARED) {
/* do not allow mprotect to make mapping writable */
vm_flags_clear(vma, VM_MAYWRITE);
if (vma->vm_flags & VM_WRITE)
return -EACCES;
}
vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP);
vma->vm_ops = &sel_mmap_policy_ops;
return 0;
}
static const struct file_operations sel_policy_ops = {
.open = sel_open_policy,
.read = sel_read_policy,
.mmap = sel_mmap_policy,
.release = sel_release_policy,
.llseek = generic_file_llseek,
};
static void sel_remove_old_bool_data(unsigned int bool_num, char **bool_names,
int *bool_values)
{
u32 i;
/* bool_dir cleanup */
for (i = 0; i < bool_num; i++)
kfree(bool_names[i]);
kfree(bool_names);
kfree(bool_values);
}
static int sel_make_policy_nodes(struct selinux_fs_info *fsi,
struct selinux_policy *newpolicy)
{
int ret = 0;
struct dentry *tmp_parent, *tmp_bool_dir, *tmp_class_dir;
unsigned int bool_num = 0;
char **bool_names = NULL;
int *bool_values = NULL;
unsigned long tmp_ino = fsi->last_ino; /* Don't increment last_ino in this function */
tmp_parent = sel_make_swapover_dir(fsi->sb, &tmp_ino);
if (IS_ERR(tmp_parent))
return PTR_ERR(tmp_parent);
tmp_ino = fsi->bool_dir->d_inode->i_ino - 1; /* sel_make_dir will increment and set */
tmp_bool_dir = sel_make_dir(tmp_parent, BOOL_DIR_NAME, &tmp_ino);
if (IS_ERR(tmp_bool_dir)) {
ret = PTR_ERR(tmp_bool_dir);
goto out;
}
tmp_ino = fsi->class_dir->d_inode->i_ino - 1; /* sel_make_dir will increment and set */
tmp_class_dir = sel_make_dir(tmp_parent, CLASS_DIR_NAME, &tmp_ino);
if (IS_ERR(tmp_class_dir)) {
ret = PTR_ERR(tmp_class_dir);
goto out;
}
ret = sel_make_bools(newpolicy, tmp_bool_dir, &bool_num,
&bool_names, &bool_values);
if (ret)
goto out;
ret = sel_make_classes(newpolicy, tmp_class_dir,
&fsi->last_class_ino);
if (ret)
goto out;
lock_rename(tmp_parent, fsi->sb->s_root);
/* booleans */
d_exchange(tmp_bool_dir, fsi->bool_dir);
swap(fsi->bool_num, bool_num);
swap(fsi->bool_pending_names, bool_names);
swap(fsi->bool_pending_values, bool_values);
fsi->bool_dir = tmp_bool_dir;
/* classes */
d_exchange(tmp_class_dir, fsi->class_dir);
fsi->class_dir = tmp_class_dir;
unlock_rename(tmp_parent, fsi->sb->s_root);
out:
sel_remove_old_bool_data(bool_num, bool_names, bool_values);
/* Since the other temporary dirs are children of tmp_parent
* this will handle all the cleanup in the case of a failure before
* the swapover
*/
simple_recursive_removal(tmp_parent, NULL);
return ret;
}
static ssize_t sel_write_load(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct selinux_fs_info *fsi;
struct selinux_load_state load_state;
ssize_t length;
void *data = NULL;
/* no partial writes */
if (*ppos)
return -EINVAL;
/* no empty policies */
if (!count)
return -EINVAL;
mutex_lock(&selinux_state.policy_mutex);
length = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__LOAD_POLICY, NULL);
if (length)
goto out;
data = vmalloc(count);
if (!data) {
length = -ENOMEM;
goto out;
}
if (copy_from_user(data, buf, count) != 0) {
length = -EFAULT;
goto out;
}
length = security_load_policy(data, count, &load_state);
if (length) {
pr_warn_ratelimited("SELinux: failed to load policy\n");
goto out;
}
fsi = file_inode(file)->i_sb->s_fs_info;
length = sel_make_policy_nodes(fsi, load_state.policy);
if (length) {
pr_warn_ratelimited("SELinux: failed to initialize selinuxfs\n");
selinux_policy_cancel(&load_state);
goto out;
}
selinux_policy_commit(&load_state);
length = count;
audit_log(audit_context(), GFP_KERNEL, AUDIT_MAC_POLICY_LOAD,
"auid=%u ses=%u lsm=selinux res=1",
from_kuid(&init_user_ns, audit_get_loginuid(current)),
audit_get_sessionid(current));
out:
mutex_unlock(&selinux_state.policy_mutex);
vfree(data);
return length;
}
static const struct file_operations sel_load_ops = {
.write = sel_write_load,
.llseek = generic_file_llseek,
};
static ssize_t sel_write_context(struct file *file, char *buf, size_t size)
{
char *canon = NULL;
u32 sid, len;
ssize_t length;
length = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__CHECK_CONTEXT, NULL);
if (length)
goto out;
length = security_context_to_sid(buf, size, &sid, GFP_KERNEL);
if (length)
goto out;
length = security_sid_to_context(sid, &canon, &len);
if (length)
goto out;
length = -ERANGE;
if (len > SIMPLE_TRANSACTION_LIMIT) {
pr_err("SELinux: %s: context size (%u) exceeds "
"payload max\n", __func__, len);
goto out;
}
memcpy(buf, canon, len);
length = len;
out:
kfree(canon);
return length;
}
static ssize_t sel_read_checkreqprot(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
char tmpbuf[TMPBUFLEN];
ssize_t length;
length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
checkreqprot_get());
return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}
static ssize_t sel_write_checkreqprot(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char *page;
ssize_t length;
unsigned int new_value;
length = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__SETCHECKREQPROT,
NULL);
if (length)
return length;
if (count >= PAGE_SIZE)
return -ENOMEM;
/* No partial writes. */
if (*ppos != 0)
return -EINVAL;
page = memdup_user_nul(buf, count);
if (IS_ERR(page))
return PTR_ERR(page);
if (sscanf(page, "%u", &new_value) != 1) {
length = -EINVAL;
goto out;
}
length = count;
if (new_value) {
char comm[sizeof(current->comm)];
strscpy(comm, current->comm);
pr_err("SELinux: %s (%d) set checkreqprot to 1. This is no longer supported.\n",
comm, current->pid);
}
selinux_ima_measure_state();
out:
kfree(page);
return length;
}
static const struct file_operations sel_checkreqprot_ops = {
.read = sel_read_checkreqprot,
.write = sel_write_checkreqprot,
.llseek = generic_file_llseek,
};
static ssize_t sel_write_validatetrans(struct file *file,
const char __user *buf,
size_t count, loff_t *ppos)
{
char *oldcon = NULL, *newcon = NULL, *taskcon = NULL;
char *req = NULL;
u32 osid, nsid, tsid;
u16 tclass;
int rc;
rc = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__VALIDATE_TRANS, NULL);
if (rc)
goto out;
rc = -ENOMEM;
if (count >= PAGE_SIZE)
goto out;
/* No partial writes. */
rc = -EINVAL;
if (*ppos != 0)
goto out;
req = memdup_user_nul(buf, count);
if (IS_ERR(req)) {
rc = PTR_ERR(req);
req = NULL;
goto out;
}
rc = -ENOMEM;
oldcon = kzalloc(count + 1, GFP_KERNEL);
if (!oldcon)
goto out;
newcon = kzalloc(count + 1, GFP_KERNEL);
if (!newcon)
goto out;
taskcon = kzalloc(count + 1, GFP_KERNEL);
if (!taskcon)
goto out;
rc = -EINVAL;
if (sscanf(req, "%s %s %hu %s", oldcon, newcon, &tclass, taskcon) != 4)
goto out;
rc = security_context_str_to_sid(oldcon, &osid, GFP_KERNEL);
if (rc)
goto out;
rc = security_context_str_to_sid(newcon, &nsid, GFP_KERNEL);
if (rc)
goto out;
rc = security_context_str_to_sid(taskcon, &tsid, GFP_KERNEL);
if (rc)
goto out;
rc = security_validate_transition_user(osid, nsid, tsid, tclass);
if (!rc)
rc = count;
out:
kfree(req);
kfree(oldcon);
kfree(newcon);
kfree(taskcon);
return rc;
}
static const struct file_operations sel_transition_ops = {
.write = sel_write_validatetrans,
.llseek = generic_file_llseek,
};
/*
* Remaining nodes use transaction based IO methods like nfsd/nfsctl.c
*/
static ssize_t sel_write_access(struct file *file, char *buf, size_t size);
static ssize_t sel_write_create(struct file *file, char *buf, size_t size);
static ssize_t sel_write_relabel(struct file *file, char *buf, size_t size);
static ssize_t sel_write_user(struct file *file, char *buf, size_t size);
static ssize_t sel_write_member(struct file *file, char *buf, size_t size);
static ssize_t (*const write_op[])(struct file *, char *, size_t) = {
[SEL_ACCESS] = sel_write_access,
[SEL_CREATE] = sel_write_create,
[SEL_RELABEL] = sel_write_relabel,
[SEL_USER] = sel_write_user,
[SEL_MEMBER] = sel_write_member,
[SEL_CONTEXT] = sel_write_context,
};
static ssize_t selinux_transaction_write(struct file *file, const char __user *buf, size_t size, loff_t *pos)
{
ino_t ino = file_inode(file)->i_ino;
char *data;
ssize_t rv;
if (ino >= ARRAY_SIZE(write_op) || !write_op[ino])
return -EINVAL;
data = simple_transaction_get(file, buf, size);
if (IS_ERR(data))
return PTR_ERR(data);
rv = write_op[ino](file, data, size);
if (rv > 0) {
simple_transaction_set(file, rv);
rv = size;
}
return rv;
}
static const struct file_operations transaction_ops = {
.write = selinux_transaction_write,
.read = simple_transaction_read,
.release = simple_transaction_release,
.llseek = generic_file_llseek,
};
/*
* payload - write methods
* If the method has a response, the response should be put in buf,
* and the length returned. Otherwise return 0 or and -error.
*/
static ssize_t sel_write_access(struct file *file, char *buf, size_t size)
{
char *scon = NULL, *tcon = NULL;
u32 ssid, tsid;
u16 tclass;
struct av_decision avd;
ssize_t length;
length = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__COMPUTE_AV, NULL);
if (length)
goto out;
length = -ENOMEM;
scon = kzalloc(size + 1, GFP_KERNEL);
if (!scon)
goto out;
length = -ENOMEM;
tcon = kzalloc(size + 1, GFP_KERNEL);
if (!tcon)
goto out;
length = -EINVAL;
if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
goto out;
length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
if (length)
goto out;
length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
if (length)
goto out;
security_compute_av_user(ssid, tsid, tclass, &avd);
length = scnprintf(buf, SIMPLE_TRANSACTION_LIMIT,
"%x %x %x %x %u %x",
avd.allowed, 0xffffffff,
avd.auditallow, avd.auditdeny,
avd.seqno, avd.flags);
out:
kfree(tcon);
kfree(scon);
return length;
}
static ssize_t sel_write_create(struct file *file, char *buf, size_t size)
{
char *scon = NULL, *tcon = NULL;
char *namebuf = NULL, *objname = NULL;
u32 ssid, tsid, newsid;
u16 tclass;
ssize_t length;
char *newcon = NULL;
u32 len;
int nargs;
length = avc_has_perm(current_sid(), SECINITSID_SECURITY,
SECCLASS_SECURITY, SECURITY__COMPUTE_CREATE,
NULL);
if (length)
goto out;
length = -ENOMEM;
scon = kzalloc(size + 1, GFP_KERNEL);
if (!scon)
goto out;
length = -ENOMEM;
tcon = kzalloc(size + 1, GFP_KERNEL);
if (!tcon)
goto out;
length = -ENOMEM;
namebuf = kzalloc(size + 1, GFP_KERNEL);
if (!namebuf)
goto out;
length = -EINVAL;
nargs = sscanf(buf, "%s %s %hu %s", scon, tcon, &tclass, namebuf);
if (nargs < 3 || nargs > 4)
goto out;
if (nargs == 4) {
/*
* If and when the name of new object to be queried contains
* either whitespace or multibyte characters, they shall be
* encoded based on the percentage-encoding rule.
* If not encoded, the sscanf logic picks up only left-half
* of the supplied name; split by a whitespace unexpectedly.
*/
char *r, *w;
int c1, c2;
r = w = namebuf;
do {
c1 = *r++;
if (c1 == '+')
c1 = ' ';
else if (c1 == '%') {
c1 = hex_to_bin(*r++);
if (c1 < 0)
goto out;
c2 = hex_to_bin(*r++);
if (c2 < 0)
goto out;
c1 = (c1 << 4) | c2;
}
*w++ = c1;
} while (c1 != '\0');
objname = namebuf;
}
length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
if (length)
goto out;
length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
if (length)
goto out;
length = security_transition_sid_user(ssid, tsid, tclass,
objname, &newsid);
if (length)
goto out;
length = security_sid_to_context(newsid, &newcon, &len);
if (length)
goto out;
length = -ERANGE;
if (len > SIMPLE_TRANSACTION_LIMIT) {
pr_err("SELinux: %s: context size (%u) exceeds "
"payload max\n", __func__, len);
goto out;
}
memcpy(buf, newcon, len);
length = len;
out:
kfree(newcon);
kfree(namebuf);
kfree(tcon);