linux-stable/security/selinux/ima.c
Linus Torvalds c269497d24 selinux/stable-5.18 PR 20220321
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Merge tag 'selinux-pr-20220321' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "We've got a number of SELinux patches queued up, the highlights are:

   - Fixup the security_fs_context_parse_param() LSM hook so it executes
     all of the LSM hook implementations unless a serious error occurs.

     We also correct the SELinux hook implementation so that it returns
     zero on success.

   - In addition to a few SELinux mount option parsing fixes, we
     simplified the parsing by moving it earlier in the process.

     The logic was that it was unlikely an admin/user would use the new
     mount API and not have the policy loaded before passing the SELinux
     options.

   - Properly fixed the LSM/SELinux/SCTP hooks with the addition of the
     security_sctp_assoc_established() hook.

     This work was done in conjunction with the netdev folks and should
     complete the move of the SCTP labeling from the endpoints to the
     associations.

   - Fixed a variety of sparse warnings caused by changes in the "__rcu"
     markings of some core kernel structures.

   - Ensure we access the superblock's LSM security blob using the
     stacking-safe accessors.

   - Added the ability for the kernel to always allow FIOCLEX and
     FIONCLEX if the "ioctl_skip_cloexec" policy capability is
     specified.

   - Various constifications improvements, type casting improvements,
     additional return value checks, and dead code/parameter removal.

   - Documentation fixes"

* tag 'selinux-pr-20220321' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: (23 commits)
  selinux: shorten the policy capability enum names
  docs: fix 'make htmldocs' warning in SCTP.rst
  selinux: allow FIOCLEX and FIONCLEX with policy capability
  selinux: use correct type for context length
  selinux: drop return statement at end of void functions
  security: implement sctp_assoc_established hook in selinux
  security: add sctp_assoc_established hook
  selinux: parse contexts for mount options early
  selinux: various sparse fixes
  selinux: try to use preparsed sid before calling parse_sid()
  selinux: Fix selinux_sb_mnt_opts_compat()
  LSM: general protection fault in legacy_parse_param
  selinux: fix a type cast problem in cred_init_security()
  selinux: drop unused macro
  selinux: simplify cred_init_security
  selinux: do not discard const qualifier in cast
  selinux: drop unused parameter of avtab_insert_node
  selinux: drop cast to same type
  selinux: enclose macro arguments in parenthesis
  selinux: declare name parameter of hash_eval const
  ...
2022-03-21 20:47:54 -07:00

125 lines
2.9 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2021 Microsoft Corporation
*
* Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
*
* Measure critical data structures maintainted by SELinux
* using IMA subsystem.
*/
#include <linux/vmalloc.h>
#include <linux/ima.h>
#include "security.h"
#include "ima.h"
/*
* selinux_ima_collect_state - Read selinux configuration settings
*
* @state: selinux_state
*
* On success returns the configuration settings string.
* On error, returns NULL.
*/
static char *selinux_ima_collect_state(struct selinux_state *state)
{
const char *on = "=1;", *off = "=0;";
char *buf;
int buf_len, len, i, rc;
buf_len = strlen("initialized=0;enforcing=0;checkreqprot=0;") + 1;
len = strlen(on);
for (i = 0; i < __POLICYDB_CAP_MAX; i++)
buf_len += strlen(selinux_policycap_names[i]) + len;
buf = kzalloc(buf_len, GFP_KERNEL);
if (!buf)
return NULL;
rc = strscpy(buf, "initialized", buf_len);
WARN_ON(rc < 0);
rc = strlcat(buf, selinux_initialized(state) ? on : off, buf_len);
WARN_ON(rc >= buf_len);
rc = strlcat(buf, "enforcing", buf_len);
WARN_ON(rc >= buf_len);
rc = strlcat(buf, enforcing_enabled(state) ? on : off, buf_len);
WARN_ON(rc >= buf_len);
rc = strlcat(buf, "checkreqprot", buf_len);
WARN_ON(rc >= buf_len);
rc = strlcat(buf, checkreqprot_get(state) ? on : off, buf_len);
WARN_ON(rc >= buf_len);
for (i = 0; i < __POLICYDB_CAP_MAX; i++) {
rc = strlcat(buf, selinux_policycap_names[i], buf_len);
WARN_ON(rc >= buf_len);
rc = strlcat(buf, state->policycap[i] ? on : off, buf_len);
WARN_ON(rc >= buf_len);
}
return buf;
}
/*
* selinux_ima_measure_state_locked - Measure SELinux state and hash of policy
*
* @state: selinux state struct
*/
void selinux_ima_measure_state_locked(struct selinux_state *state)
{
char *state_str = NULL;
void *policy = NULL;
size_t policy_len;
int rc = 0;
lockdep_assert_held(&state->policy_mutex);
state_str = selinux_ima_collect_state(state);
if (!state_str) {
pr_err("SELinux: %s: failed to read state.\n", __func__);
return;
}
ima_measure_critical_data("selinux", "selinux-state",
state_str, strlen(state_str), false,
NULL, 0);
kfree(state_str);
/*
* Measure SELinux policy only after initialization is completed.
*/
if (!selinux_initialized(state))
return;
rc = security_read_state_kernel(state, &policy, &policy_len);
if (rc) {
pr_err("SELinux: %s: failed to read policy %d.\n", __func__, rc);
return;
}
ima_measure_critical_data("selinux", "selinux-policy-hash",
policy, policy_len, true,
NULL, 0);
vfree(policy);
}
/*
* selinux_ima_measure_state - Measure SELinux state and hash of policy
*
* @state: selinux state struct
*/
void selinux_ima_measure_state(struct selinux_state *state)
{
lockdep_assert_not_held(&state->policy_mutex);
mutex_lock(&state->policy_mutex);
selinux_ima_measure_state_locked(state);
mutex_unlock(&state->policy_mutex);
}