Unverified Commit a2d2329e authored by Christian Brauner's avatar Christian Brauner
Browse files

ima: handle idmapped mounts 

IMA does sometimes access the inode's i_uid and compares it against the
rules' fowner. Enable IMA to handle idmapped mounts by passing down the
mount's user namespace. We simply make use of the helpers we introduced
before. If the initial user namespace is passed nothing changes so
non-idmapped mounts will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-27-christian.brauner@ubuntu.com


Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
parent 3cee6079

fs/attr.c

+1 −1
Original line number Diff line number Diff line
@@ -401,7 +401,7 @@ int notify_change(struct user_namespace *mnt_userns, struct dentry *dentry, 


	if (!error) {

		fsnotify_change(dentry, ia_valid);

		ima_inode_post_setattr(dentry);

		ima_inode_post_setattr(mnt_userns, dentry);

		evm_inode_post_setattr(dentry, ia_valid);

	}

fs/namei.c

+2 −2
Original line number Diff line number Diff line
@@ -3422,7 +3422,7 @@ struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns, 
		inode->i_state |= I_LINKABLE;

		spin_unlock(&inode->i_lock);

	}

	ima_post_create_tmpfile(inode);

	ima_post_create_tmpfile(mnt_userns, inode);

	return child;



out_err:
@@ -3750,7 +3750,7 @@ static long do_mknodat(int dfd, const char __user *filename, umode_t mode, 
			error = vfs_create(mnt_userns, path.dentry->d_inode,

					   dentry, mode, true);

			if (!error)

				ima_post_path_mknod(dentry);

				ima_post_path_mknod(mnt_userns, dentry);

			break;

		case S_IFCHR: case S_IFBLK:

			error = vfs_mknod(mnt_userns, path.dentry->d_inode,

include/linux/ima.h

+12 −6
Original line number Diff line number Diff line
@@ -16,7 +16,8 @@ struct linux_binprm; 
#ifdef CONFIG_IMA

extern int ima_bprm_check(struct linux_binprm *bprm);

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

extern void ima_post_create_tmpfile(struct inode *inode);

extern void ima_post_create_tmpfile(struct user_namespace *mnt_userns,

				    struct inode *inode);

extern void ima_file_free(struct file *file);

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

extern int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot);
@@ -27,7 +28,8 @@ extern int ima_read_file(struct file *file, enum kernel_read_file_id id, 
			 bool contents);

extern int ima_post_read_file(struct file *file, void *buf, loff_t size,

			      enum kernel_read_file_id id);

extern void ima_post_path_mknod(struct dentry *dentry);

extern void ima_post_path_mknod(struct user_namespace *mnt_userns,

				struct dentry *dentry);

extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);

extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size);

extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size);
@@ -68,7 +70,8 @@ static inline int ima_file_check(struct file *file, int mask) 
	return 0;

}



static inline void ima_post_create_tmpfile(struct inode *inode)

static inline void ima_post_create_tmpfile(struct user_namespace *mnt_userns,

					   struct inode *inode)

{

}
@@ -112,7 +115,8 @@ static inline int ima_post_read_file(struct file *file, void *buf, loff_t size, 
	return 0;

}



static inline void ima_post_path_mknod(struct dentry *dentry)

static inline void ima_post_path_mknod(struct user_namespace *mnt_userns,

				       struct dentry *dentry)

{

	return;

}
@@ -153,7 +157,8 @@ static inline void ima_post_key_create_or_update(struct key *keyring, 


#ifdef CONFIG_IMA_APPRAISE

extern bool is_ima_appraise_enabled(void);

extern void ima_inode_post_setattr(struct dentry *dentry);

extern void ima_inode_post_setattr(struct user_namespace *mnt_userns,

				   struct dentry *dentry);

extern int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,

		       const void *xattr_value, size_t xattr_value_len);

extern int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name);
@@ -163,7 +168,8 @@ static inline bool is_ima_appraise_enabled(void) 
	return 0;

}



static inline void ima_inode_post_setattr(struct dentry *dentry)

static inline void ima_inode_post_setattr(struct user_namespace *mnt_userns,

					  struct dentry *dentry)

{

	return;

}

security/integrity/ima/ima.h

+12 −7
Original line number Diff line number Diff line
@@ -253,8 +253,9 @@ static inline void ima_process_queued_keys(void) {} 
#endif /* CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS */



/* LIM API function definitions */

int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,

		   int mask, enum ima_hooks func, int *pcr,

int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,

		   const struct cred *cred, u32 secid, int mask,

		   enum ima_hooks func, int *pcr,

		   struct ima_template_desc **template_desc,

		   const char *keyring);

int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func);
@@ -266,7 +267,8 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file, 
			   struct evm_ima_xattr_data *xattr_value,

			   int xattr_len, const struct modsig *modsig, int pcr,

			   struct ima_template_desc *template_desc);

void process_buffer_measurement(struct inode *inode, const void *buf, int size,

void process_buffer_measurement(struct user_namespace *mnt_userns,

				struct inode *inode, const void *buf, int size,

				const char *eventname, enum ima_hooks func,

				int pcr, const char *keyring);

void ima_audit_measurement(struct integrity_iint_cache *iint,
@@ -281,8 +283,9 @@ void ima_free_template_entry(struct ima_template_entry *entry); 
const char *ima_d_path(const struct path *path, char **pathbuf, char *filename);



/* IMA policy related functions */

int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid,

		     enum ima_hooks func, int mask, int flags, int *pcr,

int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,

		     const struct cred *cred, u32 secid, enum ima_hooks func,

		     int mask, int flags, int *pcr,

		     struct ima_template_desc **template_desc,

		     const char *keyring);

void ima_init_policy(void);
@@ -313,7 +316,8 @@ int ima_appraise_measurement(enum ima_hooks func, 
			     struct file *file, const unsigned char *filename,

			     struct evm_ima_xattr_data *xattr_value,

			     int xattr_len, const struct modsig *modsig);

int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func);

int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,

		      int mask, enum ima_hooks func);

void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file);

enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,

					   enum ima_hooks func);
@@ -340,7 +344,8 @@ static inline int ima_appraise_measurement(enum ima_hooks func, 
	return INTEGRITY_UNKNOWN;

}



static inline int ima_must_appraise(struct inode *inode, int mask,

static inline int ima_must_appraise(struct user_namespace *mnt_userns,

				    struct inode *inode, int mask,

				    enum ima_hooks func)

{

	return 0;

security/integrity/ima/ima_api.c

+6 −4
Original line number Diff line number Diff line
@@ -162,6 +162,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename, 


/**

 * ima_get_action - appraise & measure decision based on policy.

 * @mnt_userns:	user namespace of the mount the inode was found from

 * @inode: pointer to the inode associated with the object being validated

 * @cred: pointer to credentials structure to validate

 * @secid: secid of the task being validated
@@ -183,8 +184,9 @@ void ima_add_violation(struct file *file, const unsigned char *filename, 
 * Returns IMA_MEASURE, IMA_APPRAISE mask.

 *

 */

int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,

		   int mask, enum ima_hooks func, int *pcr,

int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,

		   const struct cred *cred, u32 secid, int mask,

		   enum ima_hooks func, int *pcr,

		   struct ima_template_desc **template_desc,

		   const char *keyring)

{
@@ -192,8 +194,8 @@ int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid, 


	flags &= ima_policy_flag;



	return ima_match_policy(inode, cred, secid, func, mask, flags, pcr,

				template_desc, keyring);

	return ima_match_policy(mnt_userns, inode, cred, secid, func, mask,

				flags, pcr, template_desc, keyring);

}



/*