/* * AppArmor security module * * This file contains AppArmor mediation of files * * Copyright (C) 1998-2008 Novell/SUSE * Copyright 2009-2010 Canonical Ltd. * * 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. */ #include "include/apparmor.h"#include "include/audit.h"#include "include/file.h"#include "include/match.h"#include "include/path.h"#include "include/policy.h" struct file_perms nullperms;  /** * audit_file_mask - convert mask to permission string * @buffer: buffer to write string to (NOT NULL) * @mask: permission mask to convert */static void audit_file_mask(struct audit_buffer *ab, u32 mask){	char str[10]; 	char *m = str; 	if (mask & AA_EXEC_MMAP)		*m++ = 'm';	if (mask & (MAY_READ | AA_MAY_META_READ))		*m++ = 'r';	if (mask & (MAY_WRITE | AA_MAY_META_WRITE | AA_MAY_CHMOD |		    AA_MAY_CHOWN))		*m++ = 'w';	else if (mask & MAY_APPEND)		*m++ = 'a';	if (mask & AA_MAY_CREATE)		*m++ = 'c';	if (mask & AA_MAY_DELETE)		*m++ = 'd';	if (mask & AA_MAY_LINK)		*m++ = 'l';	if (mask & AA_MAY_LOCK)		*m++ = 'k';	if (mask & MAY_EXEC)		*m++ = 'x';	*m = '\0'; 	audit_log_string(ab, str);} /** * file_audit_cb - call back for file specific audit fields * @ab: audit_buffer  (NOT NULL) * @va: audit struct to audit values of  (NOT NULL) */static void file_audit_cb(struct audit_buffer *ab, void *va){	struct common_audit_data *sa = va;	uid_t fsuid = current_fsuid(); 	if (sa->aad->fs.request & AA_AUDIT_FILE_MASK) {		audit_log_format(ab, " requested_mask=");		audit_file_mask(ab, sa->aad->fs.request);	}	if (sa->aad->fs.denied & AA_AUDIT_FILE_MASK) {		audit_log_format(ab, " denied_mask=");		audit_file_mask(ab, sa->aad->fs.denied);	}	if (sa->aad->fs.request & AA_AUDIT_FILE_MASK) {		audit_log_format(ab, " fsuid=%d", fsuid);		audit_log_format(ab, " ouid=%d", sa->aad->fs.ouid);	} 	if (sa->aad->fs.target) {		audit_log_format(ab, " target=");		audit_log_untrustedstring(ab, sa->aad->fs.target);	}} /** * aa_audit_file - handle the auditing of file operations * @profile: the profile being enforced  (NOT NULL) * @perms: the permissions computed for the request (NOT NULL) * @gfp: allocation flags * @op: operation being mediated * @request: permissions requested * @name: name of object being mediated (MAYBE NULL) * @target: name of target (MAYBE NULL) * @ouid: object uid * @info: extra information message (MAYBE NULL) * @error: 0 if operation allowed else failure error code * * Returns: %0 or error on failure */int aa_audit_file(struct aa_profile *profile, struct file_perms *perms,		  gfp_t gfp, int op, u32 request, const char *name,		  const char *target, uid_t ouid, const char *info, int error){	int type = AUDIT_APPARMOR_AUTO;	struct common_audit_data sa;	struct apparmor_audit_data aad = {0,};	sa.type = LSM_AUDIT_DATA_NONE;	sa.aad = &aad;	aad.op = op,	aad.fs.request = request;	aad.name = name;	aad.fs.target = target;	aad.fs.ouid = ouid;	aad.info = info;	aad.error = error; 	if (likely(!sa.aad->error)) {		u32 mask = perms->audit; 		if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))			mask = 0xffff; 		/* mask off perms that are not being force audited */		sa.aad->fs.request &= mask; 		if (likely(!sa.aad->fs.request))			return 0;		type = AUDIT_APPARMOR_AUDIT;	} else {		/* only report permissions that were denied */		sa.aad->fs.request = sa.aad->fs.request & ~perms->allow; 		if (sa.aad->fs.request & perms->kill)			type = AUDIT_APPARMOR_KILL; 		/* quiet known rejects, assumes quiet and kill do not overlap */		if ((sa.aad->fs.request & perms->quiet) &&		    AUDIT_MODE(profile) != AUDIT_NOQUIET &&		    AUDIT_MODE(profile) != AUDIT_ALL)			sa.aad->fs.request &= ~perms->quiet; 		if (!sa.aad->fs.request)			return COMPLAIN_MODE(profile) ? 0 : sa.aad->error;	} 	sa.aad->fs.denied = sa.aad->fs.request & ~perms->allow;	return aa_audit(type, profile, gfp, &sa, file_audit_cb);} /** * map_old_perms - map old file perms layout to the new layout * @old: permission set in old mapping * * Returns: new permission mapping */static u32 map_old_perms(u32 old){	u32 new = old & 0xf;	if (old & MAY_READ)		new |= AA_MAY_META_READ;	if (old & MAY_WRITE)		new |= AA_MAY_META_WRITE | AA_MAY_CREATE | AA_MAY_DELETE |			AA_MAY_CHMOD | AA_MAY_CHOWN;	if (old & 0x10)		new |= AA_MAY_LINK;	/* the old mapping lock and link_subset flags where overlaid	 * and use was determined by part of a pair that they were in	 */	if (old & 0x20)		new |= AA_MAY_LOCK | AA_LINK_SUBSET;	if (old & 0x40)	/* AA_EXEC_MMAP */		new |= AA_EXEC_MMAP; 	return new;} /** * compute_perms - convert dfa compressed perms to internal perms * @dfa: dfa to compute perms for   (NOT NULL) * @state: state in dfa * @cond:  conditions to consider  (NOT NULL) * * TODO: convert from dfa + state to permission entry, do computation conversion *       at load time. * * Returns: computed permission set */static struct file_perms compute_perms(struct aa_dfa *dfa, unsigned int state,				       struct path_cond *cond){	struct file_perms perms; 	/* FIXME: change over to new dfa format	 * currently file perms are encoded in the dfa, new format	 * splits the permissions from the dfa.  This mapping can be	 * done at profile load	 */	perms.kill = 0; 	if (current_fsuid() == cond->uid) {		perms.allow = map_old_perms(dfa_user_allow(dfa, state));		perms.audit = map_old_perms(dfa_user_audit(dfa, state));		perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));		perms.xindex = dfa_user_xindex(dfa, state);	} else {		perms.allow = map_old_perms(dfa_other_allow(dfa, state));		perms.audit = map_old_perms(dfa_other_audit(dfa, state));		perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));		perms.xindex = dfa_other_xindex(dfa, state);	}	perms.allow |= AA_MAY_META_READ; 	/* change_profile wasn't determined by ownership in old mapping */	if (ACCEPT_TABLE(dfa)[state] & 0x80000000)		perms.allow |= AA_MAY_CHANGE_PROFILE;	if (ACCEPT_TABLE(dfa)[state] & 0x40000000)		perms.allow |= AA_MAY_ONEXEC; 	return perms;} /** * aa_str_perms - find permission that match @name * @dfa: to match against  (MAYBE NULL) * @state: state to start matching in * @name: string to match against dfa  (NOT NULL) * @cond: conditions to consider for permission set computation  (NOT NULL) * @perms: Returns - the permissions found when matching @name * * Returns: the final state in @dfa when beginning @start and walking @name */unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,			  const char *name, struct path_cond *cond,			  struct file_perms *perms){	unsigned int state;	if (!dfa) {		*perms = nullperms;		return DFA_NOMATCH;	} 	state = aa_dfa_match(dfa, start, name);	*perms = compute_perms(dfa, state, cond); 	return state;} /** * is_deleted - test if a file has been completely unlinked * @dentry: dentry of file to test for deletion  (NOT NULL) * * Returns: %1 if deleted else %0 */static inline bool is_deleted(struct dentry *dentry){	if (d_unlinked(dentry) && dentry->d_inode->i_nlink == 0)		return 1;	return 0;} /** * aa_path_perm - do permissions check & audit for @path * @op: operation being checked * @profile: profile being enforced  (NOT NULL) * @path: path to check permissions of  (NOT NULL) * @flags: any additional path flags beyond what the profile specifies * @request: requested permissions * @cond: conditional info for this request  (NOT NULL) * * Returns: %0 else error if access denied or other error */int aa_path_perm(int op, struct aa_profile *profile, struct path *path,		 int flags, u32 request, struct path_cond *cond){	char *buffer = NULL;	struct file_perms perms = {};	const char *name, *info = NULL;	int error; 	flags |= profile->path_flags | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 0);	error = aa_path_name(path, flags, &buffer, &name, &info);	if (error) {		if (error == -ENOENT && is_deleted(path->dentry)) {			/* Access to open files that are deleted are			 * give a pass (implicit delegation)			 */			error = 0;			info = NULL;			perms.allow = request;		}	} else {		aa_str_perms(profile->file.dfa, profile->file.start, name, cond,			     &perms);		if (request & ~perms.allow)			error = -EACCES;	}	error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request, name,			      NULL, cond->uid, info, error);	kfree(buffer); 	return error;} /** * xindex_is_subset - helper for aa_path_link * @link: link permission set * @target: target permission set * * test target x permissions are equal OR a subset of link x permissions * this is done as part of the subset test, where a hardlink must have * a subset of permissions that the target has. * * Returns: %1 if subset else %0 */static inline bool xindex_is_subset(u32 link, u32 target){	if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||	    ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))		return 0; 	return 1;} /** * aa_path_link - Handle hard link permission check * @profile: the profile being enforced  (NOT NULL) * @old_dentry: the target dentry  (NOT NULL) * @new_dir: directory the new link will be created in  (NOT NULL) * @new_dentry: the link being created  (NOT NULL) * * Handle the permission test for a link & target pair.  Permission * is encoded as a pair where the link permission is determined * first, and if allowed, the target is tested.  The target test * is done from the point of the link match (not start of DFA) * making the target permission dependent on the link permission match. * * The subset test if required forces that permissions granted * on link are a subset of the permission granted to target. * * Returns: %0 if allowed else error */int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,		 struct path *new_dir, struct dentry *new_dentry){	struct path link = { new_dir->mnt, new_dentry };	struct path target = { new_dir->mnt, old_dentry };	struct path_cond cond = {		old_dentry->d_inode->i_uid,		old_dentry->d_inode->i_mode	};	char *buffer = NULL, *buffer2 = NULL;	const char *lname, *tname = NULL, *info = NULL;	struct file_perms lperms, perms;	u32 request = AA_MAY_LINK;	unsigned int state;	int error; 	lperms = nullperms; 	/* buffer freed below, lname is pointer in buffer */	error = aa_path_name(&link, profile->path_flags, &buffer, &lname,			     &info);	if (error)		goto audit; 	/* buffer2 freed below, tname is pointer in buffer2 */	error = aa_path_name(&target, profile->path_flags, &buffer2, &tname,			     &info);	if (error)		goto audit; 	error = -EACCES;	/* aa_str_perms - handles the case of the dfa being NULL */	state = aa_str_perms(profile->file.dfa, profile->file.start, lname,			     &cond, &lperms); 	if (!(lperms.allow & AA_MAY_LINK))		goto audit; 	/* test to see if target can be paired with link */	state = aa_dfa_null_transition(profile->file.dfa, state);	aa_str_perms(profile->file.dfa, state, tname, &cond, &perms); 	/* force audit/quiet masks for link are stored in the second entry	 * in the link pair.	 */	lperms.audit = perms.audit;	lperms.quiet = perms.quiet;	lperms.kill = perms.kill; 	if (!(perms.allow & AA_MAY_LINK)) {		info = "target restricted";		goto audit;	} 	/* done if link subset test is not required */	if (!(perms.allow & AA_LINK_SUBSET))		goto done_tests; 	/* Do link perm subset test requiring allowed permission on link are a	 * subset of the allowed permissions on target.	 */	aa_str_perms(profile->file.dfa, profile->file.start, tname, &cond,		     &perms); 	/* AA_MAY_LINK is not considered in the subset test */	request = lperms.allow & ~AA_MAY_LINK;	lperms.allow &= perms.allow | AA_MAY_LINK; 	request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);	if (request & ~lperms.allow) {		goto audit;	} else if ((lperms.allow & MAY_EXEC) &&		   !xindex_is_subset(lperms.xindex, perms.xindex)) {		lperms.allow &= ~MAY_EXEC;		request |= MAY_EXEC;		info = "link not subset of target";		goto audit;	} done_tests:	error = 0; audit:	error = aa_audit_file(profile, &lperms, GFP_KERNEL, OP_LINK, request,			      lname, tname, cond.uid, info, error);	kfree(buffer);	kfree(buffer2); 	return error;} /** * aa_file_perm - do permission revalidation check & audit for @file * @op: operation being checked * @profile: profile being enforced   (NOT NULL) * @file: file to revalidate access permissions on  (NOT NULL) * @request: requested permissions * * Returns: %0 if access allowed else error */int aa_file_perm(int op, struct aa_profile *profile, struct file *file,		 u32 request){	struct path_cond cond = {		.uid = file->f_path.dentry->d_inode->i_uid,		.mode = file->f_path.dentry->d_inode->i_mode	}; 	return aa_path_perm(op, profile, &file->f_path, PATH_DELEGATE_DELETED,			    request, &cond);}