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Commit 3b06b3eb authored by Tyler Hicks's avatar Tyler Hicks
Browse files

eCryptfs: Fix new inode race condition 

Only unlock and d_add() new inodes after the plaintext inode size has
been read from the lower filesystem. This fixes a race condition that
was sometimes seen during a multi-job kernel build in an eCryptfs mount.

https://bugzilla.kernel.org/show_bug.cgi?id=36002



Signed-off-by: default avatarTyler Hicks <tyhicks@linux.vnet.ibm.com>
Reported-by: default avatarDavid <david@unsolicited.net>
Tested-by: default avatarDavid <david@unsolicited.net>
parent 5ccf9203

fs/ecryptfs/crypto.c

+2 −2
Original line number Diff line number Diff line
@@ -1568,11 +1568,11 @@ int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode) 
}



int ecryptfs_read_and_validate_xattr_region(char *page_virt,

					    struct dentry *ecryptfs_dentry)

					    struct inode *inode)

{

	int rc;



	rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry->d_inode);

	rc = ecryptfs_read_xattr_region(page_virt, inode);

	if (rc)

		goto out;

	if (!contains_ecryptfs_marker(page_virt	+ ECRYPTFS_FILE_SIZE_BYTES)) {

fs/ecryptfs/ecryptfs_kernel.h

+2 −2
Original line number Diff line number Diff line
@@ -662,7 +662,7 @@ void ecryptfs_write_crypt_stat_flags(char *page_virt, 
int ecryptfs_read_and_validate_header_region(char *data,

					     struct inode *ecryptfs_inode);

int ecryptfs_read_and_validate_xattr_region(char *page_virt,

					    struct dentry *ecryptfs_dentry);

					    struct inode *inode);

u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes);

int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code);

void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
@@ -753,7 +753,7 @@ int ecryptfs_privileged_open(struct file **lower_file, 
			     struct dentry *lower_dentry,

			     struct vfsmount *lower_mnt,

			     const struct cred *cred);

int ecryptfs_get_lower_file(struct dentry *ecryptfs_dentry);

int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode);

void ecryptfs_put_lower_file(struct inode *inode);

int

ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,

fs/ecryptfs/file.c

+1 −1
Original line number Diff line number Diff line
@@ -191,7 +191,7 @@ static int ecryptfs_open(struct inode *inode, struct file *file) 
				      | ECRYPTFS_ENCRYPTED);

	}

	mutex_unlock(&crypt_stat->cs_mutex);

	rc = ecryptfs_get_lower_file(ecryptfs_dentry);

	rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);

	if (rc) {

		printk(KERN_ERR "%s: Error attempting to initialize "

			"the lower file for the dentry with name "

fs/ecryptfs/inode.c

+22 −20
Original line number Diff line number Diff line
@@ -259,7 +259,8 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry) 
				"context; rc = [%d]\n", rc);

		goto out;

	}

	rc = ecryptfs_get_lower_file(ecryptfs_dentry);

	rc = ecryptfs_get_lower_file(ecryptfs_dentry,

				     ecryptfs_dentry->d_inode);

	if (rc) {

		printk(KERN_ERR "%s: Error attempting to initialize "

			"the lower file for the dentry with name "
@@ -350,50 +351,51 @@ static int ecryptfs_lookup_interpose(struct dentry *ecryptfs_dentry, 
		       __func__, rc);

		goto out;

	}

	if (!S_ISREG(inode->i_mode)) {

		if (inode->i_state & I_NEW)

			unlock_new_inode(inode);

		d_add(ecryptfs_dentry, inode);

	if (S_ISDIR(lower_inode->i_mode))

		goto out;

	if (S_ISLNK(lower_inode->i_mode))

		goto out;

	if (special_file(lower_inode->i_mode))

		goto out;

	}

	/* Released in this function */

	page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);

	if (!page_virt) {

		printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",

		       __func__);

		rc = -ENOMEM;

		make_bad_inode(inode);

		goto out;

	}

	rc = ecryptfs_get_lower_file(ecryptfs_dentry);

	rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);

	if (rc) {

		printk(KERN_ERR "%s: Error attempting to initialize "

			"the lower file for the dentry with name "

			"[%s]; rc = [%d]\n", __func__,

			ecryptfs_dentry->d_name.name, rc);

		make_bad_inode(inode);

		goto out_free_kmem;

	}

	put_lower = 1;

	crypt_stat = &ecryptfs_inode_to_private(

					ecryptfs_dentry->d_inode)->crypt_stat;

	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;

	/* TODO: lock for crypt_stat comparison */

	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))

			ecryptfs_set_default_sizes(crypt_stat);

	rc = ecryptfs_read_and_validate_header_region(page_virt,

						      ecryptfs_dentry->d_inode);

	rc = ecryptfs_read_and_validate_header_region(page_virt, inode);

	if (rc) {

		memset(page_virt, 0, PAGE_CACHE_SIZE);

		rc = ecryptfs_read_and_validate_xattr_region(page_virt,

							     ecryptfs_dentry);

							     inode);

		if (rc) {

			rc = 0;

			goto out_free_kmem;

			goto unlock_inode;

		}

		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;

	}

	ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);

	ecryptfs_i_size_init(page_virt, inode);

unlock_inode:

	if (inode->i_state & I_NEW)

		unlock_new_inode(inode);

	d_add(ecryptfs_dentry, inode);

out_free_kmem:

	kmem_cache_free(ecryptfs_header_cache_2, page_virt);

	goto out;
@@ -403,7 +405,7 @@ static int ecryptfs_lookup_interpose(struct dentry *ecryptfs_dentry, 
	d_drop(ecryptfs_dentry);

out:

	if (put_lower)

		ecryptfs_put_lower_file(ecryptfs_dentry->d_inode);

		ecryptfs_put_lower_file(inode);

	return rc;

}
@@ -843,7 +845,7 @@ static int truncate_upper(struct dentry *dentry, struct iattr *ia, 
		lower_ia->ia_valid &= ~ATTR_SIZE;

		return 0;

	}

	rc = ecryptfs_get_lower_file(dentry);

	rc = ecryptfs_get_lower_file(dentry, inode);

	if (rc)

		return rc;

	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
@@ -999,7 +1001,7 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia) 


		mount_crypt_stat = &ecryptfs_superblock_to_private(

			dentry->d_sb)->mount_crypt_stat;

		rc = ecryptfs_get_lower_file(dentry);

		rc = ecryptfs_get_lower_file(dentry, inode);

		if (rc) {

			mutex_unlock(&crypt_stat->cs_mutex);

			goto out;

fs/ecryptfs/main.c

+3 −3
Original line number Diff line number Diff line
@@ -135,12 +135,12 @@ static int ecryptfs_init_lower_file(struct dentry *dentry, 
	return rc;

}



int ecryptfs_get_lower_file(struct dentry *dentry)

int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode)

{

	struct ecryptfs_inode_info *inode_info =

		ecryptfs_inode_to_private(dentry->d_inode);

	struct ecryptfs_inode_info *inode_info;

	int count, rc = 0;



	inode_info = ecryptfs_inode_to_private(inode);

	mutex_lock(&inode_info->lower_file_mutex);

	count = atomic_inc_return(&inode_info->lower_file_count);

	if (WARN_ON_ONCE(count < 1))