linux/security/integrity/ima/ima_main.c

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/*
* Copyright (C) 2005,2006,2007,2008 IBM Corporation
*
* Authors:
* Reiner Sailer <sailer@watson.ibm.com>
* Serge Hallyn <serue@us.ibm.com>
* Kylene Hall <kylene@us.ibm.com>
* Mimi Zohar <zohar@us.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
* License.
*
* File: ima_main.c
* implements the IMA hooks: ima_bprm_check, ima_file_mmap,
* and ima_file_check.
*/
#include <linux/module.h>
#include <linux/file.h>
#include <linux/binfmts.h>
#include <linux/mount.h>
#include <linux/mman.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/slab.h>
#include "ima.h"
int ima_initialized;
char *ima_hash = "sha1";
static int __init hash_setup(char *str)
{
if (strncmp(str, "md5", 3) == 0)
ima_hash = "md5";
return 1;
}
__setup("ima_hash=", hash_setup);
struct ima_imbalance {
struct hlist_node node;
unsigned long fsmagic;
};
/*
* ima_limit_imbalance - emit one imbalance message per filesystem type
*
* Maintain list of filesystem types that do not measure files properly.
* Return false if unknown, true if known.
*/
static bool ima_limit_imbalance(struct file *file)
{
static DEFINE_SPINLOCK(ima_imbalance_lock);
static HLIST_HEAD(ima_imbalance_list);
struct super_block *sb = file->f_dentry->d_sb;
struct ima_imbalance *entry;
struct hlist_node *node;
bool found = false;
rcu_read_lock();
hlist_for_each_entry_rcu(entry, node, &ima_imbalance_list, node) {
if (entry->fsmagic == sb->s_magic) {
found = true;
break;
}
}
rcu_read_unlock();
if (found)
goto out;
entry = kmalloc(sizeof(*entry), GFP_NOFS);
if (!entry)
goto out;
entry->fsmagic = sb->s_magic;
spin_lock(&ima_imbalance_lock);
/*
* we could have raced and something else might have added this fs
* to the list, but we don't really care
*/
hlist_add_head_rcu(&entry->node, &ima_imbalance_list);
spin_unlock(&ima_imbalance_lock);
printk(KERN_INFO "IMA: unmeasured files on fsmagic: %lX\n",
entry->fsmagic);
out:
return found;
}
/*
* ima_counts_get - increment file counts
*
* Maintain read/write counters for all files, but only
* invalidate the PCR for measured files:
* - Opening a file for write when already open for read,
* results in a time of measure, time of use (ToMToU) error.
* - Opening a file for read when already open for write,
* could result in a file measurement error.
*
*/
void ima_counts_get(struct file *file)
{
struct dentry *dentry = file->f_path.dentry;
struct inode *inode = dentry->d_inode;
fmode_t mode = file->f_mode;
int rc;
bool send_tomtou = false, send_writers = false;
if (!S_ISREG(inode->i_mode))
return;
spin_lock(&inode->i_lock);
if (!ima_initialized)
goto out;
if (mode & FMODE_WRITE) {
if (inode->i_readcount && IS_IMA(inode))
send_tomtou = true;
goto out;
}
rc = ima_must_measure(NULL, inode, MAY_READ, FILE_CHECK);
if (rc < 0)
goto out;
if (atomic_read(&inode->i_writecount) > 0)
send_writers = true;
out:
/* remember the vfs deals with i_writecount */
if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
inode->i_readcount++;
spin_unlock(&inode->i_lock);
if (send_tomtou)
ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
"ToMToU");
if (send_writers)
ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
"open_writers");
}
/*
* Decrement ima counts
*/
static void ima_dec_counts(struct inode *inode, struct file *file)
{
mode_t mode = file->f_mode;
assert_spin_locked(&inode->i_lock);
if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
if (unlikely(inode->i_readcount == 0)) {
if (!ima_limit_imbalance(file)) {
printk(KERN_INFO "%s: open/free imbalance (r:%u)\n",
__func__, inode->i_readcount);
dump_stack();
}
return;
}
inode->i_readcount--;
}
}
static void ima_check_last_writer(struct ima_iint_cache *iint,
struct inode *inode,
struct file *file)
{
mode_t mode = file->f_mode;
BUG_ON(!mutex_is_locked(&iint->mutex));
assert_spin_locked(&inode->i_lock);
if (mode & FMODE_WRITE &&
atomic_read(&inode->i_writecount) == 1 &&
iint->version != inode->i_version)
iint->flags &= ~IMA_MEASURED;
}
static void ima_file_free_iint(struct ima_iint_cache *iint, struct inode *inode,
struct file *file)
{
mutex_lock(&iint->mutex);
spin_lock(&inode->i_lock);
ima_dec_counts(inode, file);
ima_check_last_writer(iint, inode, file);
spin_unlock(&inode->i_lock);
mutex_unlock(&iint->mutex);
}
static void ima_file_free_noiint(struct inode *inode, struct file *file)
{
spin_lock(&inode->i_lock);
ima_dec_counts(inode, file);
spin_unlock(&inode->i_lock);
}
/**
* ima_file_free - called on __fput()
* @file: pointer to file structure being freed
*
* Flag files that changed, based on i_version;
* and decrement the i_readcount.
*/
void ima_file_free(struct file *file)
{
struct inode *inode = file->f_dentry->d_inode;
struct ima_iint_cache *iint;
if (!iint_initialized || !S_ISREG(inode->i_mode))
return;
iint = ima_iint_find(inode);
if (iint)
ima_file_free_iint(iint, inode, file);
else
ima_file_free_noiint(inode, file);
}
static int process_measurement(struct file *file, const unsigned char *filename,
int mask, int function)
{
struct inode *inode = file->f_dentry->d_inode;
struct ima_iint_cache *iint;
int rc = 0;
if (!ima_initialized || !S_ISREG(inode->i_mode))
return 0;
rc = ima_must_measure(NULL, inode, mask, function);
if (rc != 0)
return rc;
retry:
iint = ima_iint_find(inode);
if (!iint) {
rc = ima_inode_alloc(inode);
if (!rc || rc == -EEXIST)
goto retry;
return rc;
}
mutex_lock(&iint->mutex);
rc = ima_must_measure(iint, inode, mask, function);
if (rc != 0)
goto out;
rc = ima_collect_measurement(iint, file);
if (!rc)
ima_store_measurement(iint, file, filename);
out:
mutex_unlock(&iint->mutex);
return rc;
}
/**
* ima_file_mmap - based on policy, collect/store measurement.
* @file: pointer to the file to be measured (May be NULL)
* @prot: contains the protection that will be applied by the kernel.
*
* Measure files being mmapped executable based on the ima_must_measure()
* policy decision.
*
* Return 0 on success, an error code on failure.
* (Based on the results of appraise_measurement().)
*/
int ima_file_mmap(struct file *file, unsigned long prot)
{
int rc;
if (!file)
return 0;
if (prot & PROT_EXEC)
rc = process_measurement(file, file->f_dentry->d_name.name,
MAY_EXEC, FILE_MMAP);
return 0;
}
/**
* ima_bprm_check - based on policy, collect/store measurement.
* @bprm: contains the linux_binprm structure
*
* The OS protects against an executable file, already open for write,
* from being executed in deny_write_access() and an executable file,
* already open for execute, from being modified in get_write_access().
* So we can be certain that what we verify and measure here is actually
* what is being executed.
*
* Return 0 on success, an error code on failure.
* (Based on the results of appraise_measurement().)
*/
int ima_bprm_check(struct linux_binprm *bprm)
{
int rc;
rc = process_measurement(bprm->file, bprm->filename,
MAY_EXEC, BPRM_CHECK);
return 0;
}
/**
* ima_path_check - based on policy, collect/store measurement.
* @file: pointer to the file to be measured
* @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
*
* Measure files based on the ima_must_measure() policy decision.
*
* Always return 0 and audit dentry_open failures.
* (Return code will be based upon measurement appraisal.)
*/
int ima_file_check(struct file *file, int mask)
{
int rc;
rc = process_measurement(file, file->f_dentry->d_name.name,
mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
FILE_CHECK);
return 0;
}
EXPORT_SYMBOL_GPL(ima_file_check);
static int __init init_ima(void)
{
int error;
error = ima_init();
ima_initialized = 1;
return error;
}
static void __exit cleanup_ima(void)
{
ima_cleanup();
}
late_initcall(init_ima); /* Start IMA after the TPM is available */
MODULE_DESCRIPTION("Integrity Measurement Architecture");
MODULE_LICENSE("GPL");