![John Johansen](/assets/img/avatar_default.png)
The aad macro can replace aad strings when it is not intended to. Switch to a fn macro so it is only applied when intended. Also at the same time cleanup audit_data initialization by putting common boiler plate behind a macro, and dropping the gfp_t parameter which will become useless. Signed-off-by: John Johansen <john.johansen@canonical.com>
460 lines
13 KiB
C
460 lines
13 KiB
C
/*
|
|
* 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;
|
|
kuid_t fsuid = current_fsuid();
|
|
|
|
if (aad(sa)->fs.request & AA_AUDIT_FILE_MASK) {
|
|
audit_log_format(ab, " requested_mask=");
|
|
audit_file_mask(ab, aad(sa)->fs.request);
|
|
}
|
|
if (aad(sa)->fs.denied & AA_AUDIT_FILE_MASK) {
|
|
audit_log_format(ab, " denied_mask=");
|
|
audit_file_mask(ab, aad(sa)->fs.denied);
|
|
}
|
|
if (aad(sa)->fs.request & AA_AUDIT_FILE_MASK) {
|
|
audit_log_format(ab, " fsuid=%d",
|
|
from_kuid(&init_user_ns, fsuid));
|
|
audit_log_format(ab, " ouid=%d",
|
|
from_kuid(&init_user_ns, aad(sa)->fs.ouid));
|
|
}
|
|
|
|
if (aad(sa)->fs.target) {
|
|
audit_log_format(ab, " target=");
|
|
audit_log_untrustedstring(ab, aad(sa)->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,
|
|
const char *op, u32 request, const char *name,
|
|
const char *target, kuid_t ouid, const char *info, int error)
|
|
{
|
|
int type = AUDIT_APPARMOR_AUTO;
|
|
DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
|
|
|
|
sa.u.tsk = NULL;
|
|
aad(&sa)->fs.request = request;
|
|
aad(&sa)->name = name;
|
|
aad(&sa)->fs.target = target;
|
|
aad(&sa)->fs.ouid = ouid;
|
|
aad(&sa)->info = info;
|
|
aad(&sa)->error = error;
|
|
sa.u.tsk = NULL;
|
|
|
|
if (likely(!aad(&sa)->error)) {
|
|
u32 mask = perms->audit;
|
|
|
|
if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
|
|
mask = 0xffff;
|
|
|
|
/* mask off perms that are not being force audited */
|
|
aad(&sa)->fs.request &= mask;
|
|
|
|
if (likely(!aad(&sa)->fs.request))
|
|
return 0;
|
|
type = AUDIT_APPARMOR_AUDIT;
|
|
} else {
|
|
/* only report permissions that were denied */
|
|
aad(&sa)->fs.request = aad(&sa)->fs.request & ~perms->allow;
|
|
AA_BUG(!aad(&sa)->fs.request);
|
|
|
|
if (aad(&sa)->fs.request & perms->kill)
|
|
type = AUDIT_APPARMOR_KILL;
|
|
|
|
/* quiet known rejects, assumes quiet and kill do not overlap */
|
|
if ((aad(&sa)->fs.request & perms->quiet) &&
|
|
AUDIT_MODE(profile) != AUDIT_NOQUIET &&
|
|
AUDIT_MODE(profile) != AUDIT_ALL)
|
|
aad(&sa)->fs.request &= ~perms->quiet;
|
|
|
|
if (!aad(&sa)->fs.request)
|
|
return COMPLAIN_MODE(profile) ? 0 : aad(&sa)->error;
|
|
}
|
|
|
|
aad(&sa)->fs.denied = aad(&sa)->fs.request & ~perms->allow;
|
|
return aa_audit(type, profile, &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 (uid_eq(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) && d_backing_inode(dentry)->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(const char *op, struct aa_profile *profile,
|
|
const 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, 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,
|
|
const struct path *new_dir, struct dentry *new_dentry)
|
|
{
|
|
struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
|
|
struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
|
|
struct path_cond cond = {
|
|
d_backing_inode(old_dentry)->i_uid,
|
|
d_backing_inode(old_dentry)->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, 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(const char *op, struct aa_profile *profile, struct file *file,
|
|
u32 request)
|
|
{
|
|
struct path_cond cond = {
|
|
.uid = file_inode(file)->i_uid,
|
|
.mode = file_inode(file)->i_mode
|
|
};
|
|
|
|
return aa_path_perm(op, profile, &file->f_path, PATH_DELEGATE_DELETED,
|
|
request, &cond);
|
|
}
|