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Commit 8eb988c7 authored by Mimi Zohar's avatar Mimi Zohar Committed by Al Viro
Browse files

fix ima breakage 



The "Untangling ima mess, part 2 with counters" patch messed
up the counters.  Based on conversations with Al Viro, this patch
streamlines ima_path_check() by removing the counter maintaince.
The counters are now updated independently, from measuring the file,
in __dentry_open() and alloc_file() by calling ima_counts_get().
ima_path_check() is called from nfsd and do_filp_open().
It also did not measure all files that should have been measured.
Reason: ima_path_check() got bogus value passed as mask.
[AV: mea culpa]
[AV: add missing nfsd bits]

Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 1e41568d

fs/namei.c

+2 −4
Original line number Diff line number Diff line
@@ -1736,8 +1736,7 @@ do_last: 
		if (nd.root.mnt)

			path_put(&nd.root);

		if (!IS_ERR(filp)) {

			error = ima_path_check(&filp->f_path, filp->f_mode &

				       (MAY_READ | MAY_WRITE | MAY_EXEC));

			error = ima_path_check(filp, acc_mode);

			if (error) {

				fput(filp);

				filp = ERR_PTR(error);
@@ -1797,8 +1796,7 @@ ok: 
	}

	filp = nameidata_to_filp(&nd);

	if (!IS_ERR(filp)) {

		error = ima_path_check(&filp->f_path, filp->f_mode &

			       (MAY_READ | MAY_WRITE | MAY_EXEC));

		error = ima_path_check(filp, acc_mode);

		if (error) {

			fput(filp);

			filp = ERR_PTR(error);

fs/nfsd/vfs.c

+1 −2
Original line number Diff line number Diff line
@@ -752,8 +752,7 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, 
			    flags, current_cred());

	if (IS_ERR(*filp))

		host_err = PTR_ERR(*filp);

	host_err = ima_path_check(&(*filp)->f_path,

				  access & (MAY_READ | MAY_WRITE | MAY_EXEC));

	host_err = ima_path_check(*filp, access);

out_nfserr:

	err = nfserrno(host_err);

out:

include/linux/ima.h

+2 −2
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ struct linux_binprm; 
extern int ima_bprm_check(struct linux_binprm *bprm);

extern int ima_inode_alloc(struct inode *inode);

extern void ima_inode_free(struct inode *inode);

extern int ima_path_check(struct path *path, int mask);

extern int ima_path_check(struct file *file, int mask);

extern void ima_file_free(struct file *file);

extern int ima_file_mmap(struct file *file, unsigned long prot);

extern void ima_counts_get(struct file *file);
@@ -38,7 +38,7 @@ static inline void ima_inode_free(struct inode *inode) 
	return;

}



static inline int ima_path_check(struct path *path, int mask)

static inline int ima_path_check(struct file *file, int mask)

{

	return 0;

}

security/integrity/ima/ima_main.c

+92 −144
Original line number Diff line number Diff line
@@ -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

 */
@@ -98,6 +128,47 @@ static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode) 
		iint->writecount++;

}



/*

 * 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

 */
@@ -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;