diff options
author | Ingo Molnar <mingo@elte.hu> | 2009-03-31 13:53:43 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-03-31 13:53:43 +0200 |
commit | 7bee946358c3cb957d4aa648fc5ab3cad0b232d0 (patch) | |
tree | 693061ebde2abc35ecc846e5084630d7225aaaff /security/integrity/ima/ima_main.c | |
parent | d820ac4c2fa881079e6b689d2098adce337558ae (diff) | |
parent | 15f7176eb1cccec0a332541285ee752b935c1c85 (diff) |
Merge branch 'linus' into locking-for-linus
Conflicts:
lib/Kconfig.debug
Diffstat (limited to 'security/integrity/ima/ima_main.c')
-rw-r--r-- | security/integrity/ima/ima_main.c | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c new file mode 100644 index 00000000000..f4e7266f5ae --- /dev/null +++ b/security/integrity/ima/ima_main.c @@ -0,0 +1,327 @@ +/* + * 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_path_check. + */ +#include <linux/module.h> +#include <linux/file.h> +#include <linux/binfmts.h> +#include <linux/mount.h> +#include <linux/mman.h> + +#include "ima.h" + +int ima_initialized; + +char *ima_hash = "sha1"; +static int __init hash_setup(char *str) +{ + const char *op = "hash_setup"; + const char *hash = "sha1"; + int result = 0; + int audit_info = 0; + + if (strncmp(str, "md5", 3) == 0) { + hash = "md5"; + ima_hash = str; + } else if (strncmp(str, "sha1", 4) != 0) { + hash = "invalid_hash_type"; + result = 1; + } + integrity_audit_msg(AUDIT_INTEGRITY_HASH, NULL, NULL, op, hash, + result, audit_info); + return 1; +} +__setup("ima_hash=", hash_setup); + +/** + * ima_file_free - called on __fput() + * @file: pointer to file structure being freed + * + * Flag files that changed, based on i_version; + * and decrement the iint readcount/writecount. + */ +void ima_file_free(struct file *file) +{ + struct inode *inode = file->f_dentry->d_inode; + struct ima_iint_cache *iint; + + if (!ima_initialized || !S_ISREG(inode->i_mode)) + return; + iint = ima_iint_find_get(inode); + if (!iint) + return; + + mutex_lock(&iint->mutex); + if (iint->opencount <= 0) { + printk(KERN_INFO + "%s: %s open/free imbalance (r:%ld w:%ld o:%ld f:%ld)\n", + __FUNCTION__, file->f_dentry->d_name.name, + iint->readcount, iint->writecount, + iint->opencount, atomic_long_read(&file->f_count)); + if (!(iint->flags & IMA_IINT_DUMP_STACK)) { + dump_stack(); + iint->flags |= IMA_IINT_DUMP_STACK; + } + } + iint->opencount--; + + if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) + iint->readcount--; + + if (file->f_mode & FMODE_WRITE) { + iint->writecount--; + if (iint->writecount == 0) { + if (iint->version != inode->i_version) + iint->flags &= ~IMA_MEASURED; + } + } + mutex_unlock(&iint->mutex); + kref_put(&iint->refcount, iint_free); +} + +/* ima_read_write_check - reflect possible reading/writing errors in the PCR. + * + * When opening a file for read, if the file is already open for write, + * the file could change, resulting in a file measurement error. + * + * Opening a file for write, if the file is already open for read, results + * in a time of measure, time of use (ToMToU) error. + * + * In either case invalidate the PCR. + */ +enum iint_pcr_error { TOMTOU, OPEN_WRITERS }; +static void ima_read_write_check(enum iint_pcr_error error, + struct ima_iint_cache *iint, + struct inode *inode, + const unsigned char *filename) +{ + switch (error) { + case TOMTOU: + if (iint->readcount > 0) + ima_add_violation(inode, filename, "invalid_pcr", + "ToMToU"); + break; + case OPEN_WRITERS: + if (iint->writecount > 0) + ima_add_violation(inode, filename, "invalid_pcr", + "open_writers"); + break; + } +} + +static int get_path_measurement(struct ima_iint_cache *iint, struct file *file, + const unsigned char *filename) +{ + int rc = 0; + + if (IS_ERR(file)) { + pr_info("%s dentry_open failed\n", filename); + return rc; + } + iint->opencount++; + iint->readcount++; + + rc = ima_collect_measurement(iint, file); + if (!rc) + ima_store_measurement(iint, file, filename); + return rc; +} + +/** + * ima_path_check - based on policy, collect/store measurement. + * @path: contains a pointer to the path to be measured + * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE + * + * Measure the file being open for readonly, based on the + * ima_must_measure() policy decision. + * + * Keep 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. + * + * Return 0 on success, an error code on failure. + * (Based on the results of appraise_measurement().) + */ +int ima_path_check(struct path *path, int mask) +{ + struct inode *inode = path->dentry->d_inode; + struct ima_iint_cache *iint; + struct file *file = NULL; + int rc; + + if (!ima_initialized || !S_ISREG(inode->i_mode)) + return 0; + iint = ima_iint_find_insert_get(inode); + if (!iint) + return 0; + + mutex_lock(&iint->mutex); + iint->opencount++; + if ((mask & MAY_WRITE) || (mask == 0)) + iint->writecount++; + else if (mask & (MAY_READ | MAY_EXEC)) + iint->readcount++; + + rc = ima_must_measure(iint, inode, MAY_READ, PATH_CHECK); + if (rc < 0) + goto out; + + if ((mask & MAY_WRITE) || (mask == 0)) + ima_read_write_check(TOMTOU, iint, inode, + path->dentry->d_name.name); + + if ((mask & (MAY_WRITE | MAY_READ | MAY_EXEC)) != MAY_READ) + goto out; + + ima_read_write_check(OPEN_WRITERS, iint, inode, + path->dentry->d_name.name); + if (!(iint->flags & IMA_MEASURED)) { + struct dentry *dentry = dget(path->dentry); + struct vfsmount *mnt = mntget(path->mnt); + + file = dentry_open(dentry, mnt, O_RDONLY, current->cred); + rc = get_path_measurement(iint, file, dentry->d_name.name); + } +out: + mutex_unlock(&iint->mutex); + if (file) + fput(file); + kref_put(&iint->refcount, iint_free); + return 0; +} + +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; + + if (!ima_initialized || !S_ISREG(inode->i_mode)) + return 0; + iint = ima_iint_find_insert_get(inode); + if (!iint) + return -ENOMEM; + + 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); + kref_put(&iint->refcount, iint_free); + return rc; +} + +static void opencount_get(struct file *file) +{ + struct inode *inode = file->f_dentry->d_inode; + struct ima_iint_cache *iint; + + if (!ima_initialized || !S_ISREG(inode->i_mode)) + return; + iint = ima_iint_find_insert_get(inode); + if (!iint) + return; + mutex_lock(&iint->mutex); + iint->opencount++; + mutex_unlock(&iint->mutex); +} + +/** + * 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_shm_check - IPC shm and shmat create/fput a file + * + * Maintain the opencount for these files to prevent unnecessary + * imbalance messages. + */ +void ima_shm_check(struct file *file) +{ + opencount_get(file); + return; +} + +/** + * 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; +} + +static int __init init_ima(void) +{ + int error; + + ima_iintcache_init(); + 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"); |