diff options
Diffstat (limited to 'security')
| -rw-r--r-- | security/integrity/ima/ima_main.c | 236 |
1 files changed, 92 insertions, 144 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index a89f44d5e030..75aee18f6163 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -84,6 +84,36 @@ out: return found; } +/* 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; + } +} + /* * Update the counts given an fmode_t */ @@ -99,6 +129,47 @@ static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode) } /* + * 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; + struct ima_iint_cache *iint; + int rc; + + if (!ima_initialized || !S_ISREG(inode->i_mode)) + return; + iint = ima_iint_find_get(inode); + if (!iint) + return; + mutex_lock(&iint->mutex); + rc = ima_must_measure(iint, inode, MAY_READ, PATH_CHECK); + if (rc < 0) + goto out; + + if (mode & FMODE_WRITE) { + ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name); + goto out; + } + ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name); +out: + ima_inc_counts(iint, file->f_mode); + mutex_unlock(&iint->mutex); + + kref_put(&iint->refcount, iint_free); +} + +/* * Decrement ima counts */ static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode, @@ -153,123 +224,6 @@ void ima_file_free(struct file *file) 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; - - ima_inc_counts(iint, file->f_mode); - - 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. - * - * Always return 0 and audit dentry_open failures. - * (Return code will be based upon measurement appraisal.) - */ -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_get(inode); - if (!iint) - return 0; - - mutex_lock(&iint->mutex); - - 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 | O_LARGEFILE, - current_cred()); - if (IS_ERR(file)) { - int audit_info = 0; - - integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, - dentry->d_name.name, - "add_measurement", - "dentry_open failed", - 1, audit_info); - file = NULL; - goto out; - } - 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; -} -EXPORT_SYMBOL_GPL(ima_path_check); - static int process_measurement(struct file *file, const unsigned char *filename, int mask, int function) { @@ -297,33 +251,6 @@ out: return rc; } -/* - * ima_counts_get - increment file counts - * - * - for IPC shm and shmat file. - * - for nfsd exported files. - * - * Increment the counts for these files to prevent unnecessary - * imbalance messages. - */ -void ima_counts_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_get(inode); - if (!iint) - return; - mutex_lock(&iint->mutex); - ima_inc_counts(iint, file->f_mode); - mutex_unlock(&iint->mutex); - - kref_put(&iint->refcount, iint_free); -} -EXPORT_SYMBOL_GPL(ima_counts_get); - /** * ima_file_mmap - based on policy, collect/store measurement. * @file: pointer to the file to be measured (May be NULL) @@ -369,6 +296,27 @@ int ima_bprm_check(struct linux_binprm *bprm) 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_path_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), + PATH_CHECK); + return 0; +} +EXPORT_SYMBOL_GPL(ima_path_check); + static int __init init_ima(void) { int error; |