// SPDX-License-Identifier: GPL-2.0-only
/*
* AppArmor security module
*
* This file contains AppArmor policy attachment and domain transitions
*
* Copyright (C) 2002-2008 Novell/SUSE
* Copyright 2009-2010 Canonical Ltd.
*/
#include <linux/errno.h>
#include <linux/fdtable.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/syscalls.h>
#include <linux/personality.h>
#include <linux/xattr.h>
#include <linux/user_namespace.h>
#include "include/audit.h"
#include "include/apparmorfs.h"
#include "include/cred.h"
#include "include/domain.h"
#include "include/file.h"
#include "include/ipc.h"
#include "include/match.h"
#include "include/path.h"
#include "include/policy.h"
#include "include/policy_ns.h"
/**
* may_change_ptraced_domain - check if can change profile on ptraced task
* @to_cred: cred of task changing domain
* @to_label: profile to change to (NOT NULL)
* @info: message if there is an error
*
* Check if current is ptraced and if so if the tracing task is allowed
* to trace the new domain
*
* Returns: %0 or error if change not allowed
*/
static int may_change_ptraced_domain(const struct cred *to_cred,
struct aa_label *to_label,
const char **info)
{
struct task_struct *tracer;
struct aa_label *tracerl = NULL;
const struct cred *tracer_cred = NULL;
int error = 0;
rcu_read_lock();
tracer = ptrace_parent(current);
if (tracer) {
/* released below */
tracerl = aa_get_task_label(tracer);
tracer_cred = get_task_cred(tracer);
}
/* not ptraced */
if (!tracer || unconfined(tracerl))
goto out;
error = aa_may_ptrace(tracer_cred, tracerl, to_cred, to_label,
PTRACE_MODE_ATTACH);
out:
rcu_read_unlock();
aa_put_label(tracerl);
put_cred(tracer_cred);
if (error)
*info = "ptrace prevents transition";
return error;
}
/**** TODO: dedup to aa_label_match - needs perm and dfa, merging
* specifically this is an exact copy of aa_label_match except
* aa_compute_perms is replaced with aa_compute_fperms
* and policy->dfa with file->dfa
****/
/* match a profile and its associated ns component if needed
* Assumes visibility test has already been done.
* If a subns profile is not to be matched should be prescreened with
* visibility test.
*/
static inline aa_state_t match_component(struct aa_profile *profile,
struct aa_profile *tp,
bool stack, aa_state_t state)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
const char *ns_name;
if (stack)
state = aa_dfa_match(rules->file->dfa, state, "&");
if (profile->ns == tp->ns)
return aa_dfa_match(rules->file->dfa, state, tp->base.hname);
/* try matching with namespace name and then profile */
ns_name = aa_ns_name(profile->ns, tp->ns, true);
state = aa_dfa_match_len(rules->file->dfa, state, ":", 1);
state = aa_dfa_match(rules->file->dfa, state, ns_name);
state = aa_dfa_match_len(rules->file->dfa, state, ":", 1);
return aa_dfa_match(rules->file->dfa, state, tp->base.hname);
}
/**
* label_compound_match - find perms for full compound label
* @profile: profile to find perms for
* @label: label to check access permissions for
* @stack: whether this is a stacking request
* @state: state to start match in
* @subns: whether to do permission checks on components in a subns
* @request: permissions to request
* @perms: perms struct to set
*
* Returns: 0 on success else ERROR
*
* For the label A//&B//&C this does the perm match for A//&B//&C
* @perms should be preinitialized with allperms OR a previous permission
* check to be stacked.
*/
static int label_compound_match(struct aa_profile *profile,
struct aa_label *label, bool stack,
aa_state_t state, bool subns, u32 request,
struct aa_perms *perms)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
struct aa_profile *tp;
struct label_it i;
struct path_cond cond = { };
/* find first subcomponent that is visible */
label_for_each(i, label, tp) {
if (!aa_ns_visible(profile->ns, tp->ns, subns))
continue;
state = match_component(profile, tp, stack, state);
if (!state)
goto fail;
goto next;
}
/* no component visible */
*perms = allperms;
return 0;
next:
label_for_each_cont(i, label, tp) {
if (!aa_ns_visible(profile->ns, tp->ns, subns))
continue;
state = aa_dfa_match(rules->file->dfa, state, "//&");
state = match_component(profile, tp, false, state);
if (!state)
goto fail;
}
*perms = *(aa_lookup_fperms(rules->file, state, &cond));
aa_apply_modes_to_perms(profile, perms);
if ((perms->allow & request) != request)
return -EACCES;
return 0;
fail:
*perms = nullperms;
return -EACCES;
}
/**
* label_components_match - find perms for all subcomponents of a label
* @profile: profile to find perms for
* @label: label to check access permissions for
* @stack: whether this is a stacking request
* @start: state to start match in
* @subns: whether to do permission checks on components in a subns
* @request: permissions to request
* @perms: an initialized perms struct to add accumulation to
*
* Returns: 0 on success else ERROR
*
* For the label A//&B//&C this does the perm match for each of A and B and C
* @perms should be preinitialized with allperms OR a previous permission
* check to be stacked.
*/
static int label_components_match(struct aa_profile *profile,
struct aa_label *label, bool stack,
aa_state_t start, bool subns, u32 request,
struct aa_perms *perms)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
struct aa_profile *tp;
struct label_it i;
struct aa_perms tmp;
struct path_cond cond = { };
aa_state_t state = 0;
/* find first subcomponent to test */
label_for_each(i, label, tp) {
if (!aa_ns_visible(profile->ns, tp->ns, subns))
continue;
state = match_component(profile, tp, stack, start);
if (!state)
goto fail;
goto next;
}
/* no subcomponents visible - no change in perms */
return 0;
next:
tmp = *(aa_lookup_fperms(rules->file, state, &cond));
aa_apply_modes_to_perms(profile, &tmp);
aa_perms_accum(perms, &tmp);
label_for_each_cont(i, label, tp) {
if (!aa_ns_visible(profile->ns, tp->ns, subns))
continue;
state = match_component(profile, tp, stack, start);
if (!state)
goto fail;
tmp = *(aa_lookup_fperms(rules->file, state, &cond));
aa_apply_modes_to_perms(profile, &tmp);
aa_perms_accum(perms, &tmp);
}
if ((perms->allow & request) != request)
return -EACCES;
return 0;
fail:
*perms = nullperms;
return -EACCES;
}
/**
* label_match - do a multi-component label match
* @profile: profile to match against (NOT NULL)
* @label: label to match (NOT NULL)
* @stack: whether this is a stacking request
* @state: state to start in
* @subns: whether to match subns components
* @request: permission request
* @perms: Returns computed perms (NOT NULL)
*
* Returns: the state the match finished in, may be the none matching state
*/
static int label_match(struct aa_profile *profile, struct aa_label *label,
bool stack, aa_state_t state, bool subns, u32 request,
struct aa_perms *perms)
{
int error;
*perms = nullperms;
error = label_compound_match(profile, label, stack, state, subns,
request, perms);
if (!error)
return error;
*perms = allperms;
return label_components_match(profile, label, stack, state, subns,
request, perms);
}
/******* end TODO: dedup *****/
/**
* change_profile_perms - find permissions for change_profile
* @profile: the current profile (NOT NULL)
* @target: label to transition to (NOT NULL)
* @stack: whether this is a stacking request
* @request: requested perms
* @start: state to start matching in
* @perms: Returns computed perms (NOT NULL)
*
*
* Returns: permission set
*
* currently only matches full label A//&B//&C or individual components A, B, C
* not arbitrary combinations. Eg. A//&B, C
*/
static int change_profile_perms(struct aa_profile *profile,
struct aa_label *target, bool stack,
u32 request, aa_state_t start,
struct aa_perms *perms)
{
if (profile_unconfined(profile)) {
perms->allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
perms->audit = perms->quiet = perms->kill = 0;
return 0;
}
/* TODO: add profile in ns screening */
return label_match(profile, target, stack, start, true, request, perms);
}
/**
* aa_xattrs_match - check whether a file matches the xattrs defined in profile
* @bprm: binprm struct for the process to validate
* @profile: profile to match against (NOT NULL)
* @state: state to start match in
*
* Returns: number of extended attributes that matched, or < 0 on error
*/
static int aa_xattrs_match(const struct linux_binprm *bprm,
struct aa_profile *profile, aa_state_t state)
{
int i;
struct dentry *d;
char *value = NULL;
struct aa_attachment *attach = &profile->attach;
int size, value_size = 0, ret = attach->xattr_count;
if (!bprm || !attach->xattr_count)
return 0;
might_sleep();
/* transition from exec match to xattr set */
state = aa_dfa_outofband_transition(attach->xmatch->dfa, state);
d = bprm->file->f_path.dentry;
for (i = 0; i < attach->xattr_count; i++) {
size = vfs_getxattr_alloc(&nop_mnt_idmap, d, attach->xattrs[i],
&value, value_size, GFP_KERNEL);
if (size >= 0) {
u32 index, perm;
/*
* Check the xattr presence before value. This ensure
* that not present xattr can be distinguished from a 0
* length value or rule that matches any value
*/
state = aa_dfa_null_transition(attach->xmatch->dfa,
state);
/* Check xattr value */
state = aa_dfa_match_len(attach->xmatch->dfa, state,
value, size);
index = ACCEPT_TABLE(attach->xmatch->dfa)[state];
perm = attach->xmatch->perms[index].allow;
if (!(perm & MAY_EXEC)) {
ret = -EINVAL;
goto out;
}
}
/* transition to next element */
state = aa_dfa_outofband_transition(attach->xmatch->dfa, state);
if (size < 0) {
/*
* No xattr match, so verify if transition to
* next element was valid. IFF so the xattr
* was optional.
*/
if (!state) {
ret = -EINVAL;
goto out;
}
/* don't count missing optional xattr as matched */
ret--;
}
}
out:
kfree(value);
return ret;
}
/**
* find_attach - do attachment search for unconfined processes
* @bprm: binprm structure of transitioning task
* @ns: the current namespace (NOT NULL)
* @head: profile list to walk (NOT NULL)
* @name: to match against (NOT NULL)
* @info: info message if there was an error (NOT NULL)
*
* Do a linear search on the profiles in the list. There is a matching
* preference where an exact match is preferred over a name which uses
* expressions to match, and matching expressions with the greatest
* xmatch_len are preferred.
*
* Requires: @head not be shared or have appropriate locks held
*
* Returns: label or NULL if no match found
*/
static struct aa_label *find_attach(const struct linux_binprm *bprm,
struct aa_ns *ns, struct list_head *head,
const char *name, const char **info)
{
int candidate_len = 0, candidate_xattrs = 0;
bool conflict = false;
struct aa_profile *profile, *candidate = NULL;
AA_BUG(!name);
AA_BUG(!head);
rcu_read_lock();
restart:
list_for_each_entry_rcu(profile, head, base.list) {
struct aa_attachment *attach = &profile->attach;
if (profile->label.flags & FLAG_NULL &&
&profile->label == ns_unconfined(profile->ns))
continue;
/* Find the "best" matching profile. Profiles must
* match the path and extended attributes (if any)
* associated with the file. A more specific path
* match will be preferred over a less specific one,
* and a match with more matching extended attributes
* will be preferred over one with fewer. If the best
* match has both the same level of path specificity
* and the same number of matching extended attributes
* as another profile, signal a conflict and refuse to
* match.
*/
if (attach->xmatch->dfa) {
unsigned int count;
aa_state_t state;
u32 index, perm;
state = aa_dfa_leftmatch(attach->xmatch->dfa,
attach->xmatch->start[AA_CLASS_XMATCH],
name, &count);
index = ACCEPT_TABLE(attach->xmatch->dfa)[state];
perm = attach->xmatch->perms[index].allow;
/* any accepting state means a valid match. */
if (perm & MAY_EXEC) {
int ret = 0;
if (count < candidate_len)
continue;
if (bprm && attach->xattr_count) {
long rev = READ_ONCE(ns->revision);
if (!aa_get_profile_not0(profile))
goto restart;
rcu_read_unlock();
ret = aa_xattrs_match(bprm, profile,
state);
rcu_read_lock();
aa_put_profile(profile);
if (rev !=
READ_ONCE(ns->revision))
/* policy changed */
goto restart;
/*
* Fail matching if the xattrs don't
* match
*/
if (ret < 0)
continue;
}
/*
* TODO: allow for more flexible best match
*
* The new match isn't more specific
* than the current best match
*/
if (count == candidate_len &&
ret <= candidate_xattrs) {
/* Match is equivalent, so conflict */
if (ret == candidate_xattrs)
conflict = true;
continue;
}
/* Either the same length with more matching
* xattrs, or a longer match
*/
candidate = profile;
candidate_len = max(count, attach->xmatch_len);
candidate_xattrs = ret;
conflict = false;
}
} else if (!strcmp(profile->base.name, name)) {
/*
* old exact non-re match, without conditionals such
* as xattrs. no more searching required
*/
candidate = profile;
goto out;
}
}
if (!candidate || conflict) {
if (conflict)
*info = "conflicting profile attachments";
rcu_read_unlock();
return NULL;
}
out:
candidate = aa_get_newest_profile(candidate);
rcu_read_unlock();
return &candidate->label;
}
static const char *next_name(int xtype, const char *name)
{
return NULL;
}
/**
* x_table_lookup - lookup an x transition name via transition table
* @profile: current profile (NOT NULL)
* @xindex: index into x transition table
* @name: returns: name tested to find label (NOT NULL)
*
* Returns: refcounted label, or NULL on failure (MAYBE NULL)
*/
struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
const char **name)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
struct aa_label *label = NULL;
u32 xtype = xindex & AA_X_TYPE_MASK;
int index = xindex & AA_X_INDEX_MASK;
AA_BUG(!name);
/* index is guaranteed to be in range, validated at load time */
/* TODO: move lookup parsing to unpack time so this is a straight
* index into the resultant label
*/
for (*name = rules->file->trans.table[index]; !label && *name;
*name = next_name(xtype, *name)) {
if (xindex & AA_X_CHILD) {
struct aa_profile *new_profile;
/* release by caller */
new_profile = aa_find_child(profile, *name);
if (new_profile)
label = &new_profile->label;
continue;
}
label = aa_label_parse(&profile->label, *name, GFP_KERNEL,
true, false);
if (IS_ERR(label))
label = NULL;
}
/* released by caller */
return label;
}
/**
* x_to_label - get target label for a given xindex
* @profile: current profile (NOT NULL)
* @bprm: binprm structure of transitioning task
* @name: name to lookup (NOT NULL)
* @xindex: index into x transition table
* @lookupname: returns: name used in lookup if one was specified (NOT NULL)
* @info: info message if there was an error (NOT NULL)
*
* find label for a transition index
*
* Returns: refcounted label or NULL if not found available
*/
static struct aa_label *x_to_label(struct aa_profile *profile,
const struct linux_binprm *bprm,
const char *name, u32 xindex,
const char **lookupname,
const char **info)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
struct aa_label *new = NULL;
struct aa_ns *ns = profile->ns;
u32 xtype = xindex & AA_X_TYPE_MASK;
const char *stack = NULL;
switch (xtype) {
case AA_X_NONE:
/* fail exec unless ix || ux fallback - handled by caller */
*lookupname = NULL;
break;
case AA_X_TABLE:
/* TODO: fix when perm mapping done at unload */
stack = rules->file->trans.table[xindex & AA_X_INDEX_MASK];
if (*stack != '&') {
/* released by caller */
new = x_table_lookup(profile, xindex, lookupname);
stack = NULL;
break;
}
fallthrough; /* to X_NAME */
case AA_X_NAME:
if (xindex & AA_X_CHILD)
/* released by caller */
new = find_attach(bprm, ns, &profile->base.profiles,
name, info);
else
/* released by caller */
new = find_attach(bprm, ns, &ns->base.profiles,
name, info);
*lookupname = name;
break;
}
if (!new) {
if (xindex & AA_X_INHERIT) {
/* (p|c|n)ix - don't change profile but do
* use the newest version
*/
*info = "ix fallback";
/* no profile && no error */
new = aa_get_newest_label(&profile->label);
} else if (xindex & AA_X_UNCONFINED) {
new = aa_get_newest_label(ns_unconfined(profile->ns));
*info = "ux fallback";
}
}
if (new && stack) {
/* base the stack on post domain transition */
struct aa_label *base = new;
new = aa_label_parse(base, stack, GFP_KERNEL, true, false);
if (IS_ERR(new))
new = NULL;
aa_put_label(base);
}
/* released by caller */
return new;
}
static struct aa_label *profile_transition(const struct cred *subj_cred,
struct aa_profile *profile,
const struct linux_binprm *bprm,
char *buffer, struct path_cond *cond,
bool *secure_exec)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
struct aa_label *new = NULL;
const char *info = NULL, *name = NULL, *target = NULL;
aa_state_t state = rules->file->start[AA_CLASS_FILE];
struct aa_perms perms = {};
bool nonewprivs = false;
int error = 0;
AA_BUG(!profile);
AA_BUG(!bprm);
AA_BUG(!buffer);
error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
&name, &info, profile->disconnected);
if (error) {
if (profile_unconfined(profile) ||
(profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
AA_DEBUG("name lookup ix on error");
error = 0;
new = aa_get_newest_label(&profile->label);
}
name = bprm->filename;
goto audit;
}
if (profile_unconfined(profile)) {
new = find_attach(bprm, profile->ns,
&profile->ns->base.profiles, name, &info);
if (new) {
AA_DEBUG("unconfined attached to new label");
return new;
}
AA_DEBUG("unconfined exec no attachment");
return aa_get_newest_label(&profile->label);
}
/* find exec permissions for name */
state = aa_str_perms(rules->file, state, name, cond, &perms);
if (perms.allow & MAY_EXEC) {
/* exec permission determine how to transition */
new = x_to_label(profile, bprm, name, perms.xindex, &target,
&info);
if (new && new->proxy == profile->label.proxy && info) {
/* hack ix fallback - improve how this is detected */
goto audit;
} else if (!new) {
error = -EACCES;
info = "profile transition not found";
/* remove MAY_EXEC to audit as failure */
perms.allow &= ~MAY_EXEC;
}
} else if (COMPLAIN_MODE(profile)) {
/* no exec permission - learning mode */
struct aa_profile *new_profile = NULL;
new_profile = aa_new_learning_profile(profile, false, name,
GFP_KERNEL);
if (!new_profile) {
error = -ENOMEM;
info = "could not create null profile";
} else {
error = -EACCES;
new = &new_profile->label;
}
perms.xindex |= AA_X_UNSAFE;
} else
/* fail exec */
error = -EACCES;
if (!new)
goto audit;
if (!(perms.xindex & AA_X_UNSAFE)) {
if (DEBUG_ON) {
dbg_printk("apparmor: scrubbing environment variables"
" for %s profile=", name);
aa_label_printk(new, GFP_KERNEL);
dbg_printk("\n");
}
*secure_exec = true;
}
audit:
aa_audit_file(subj_cred, profile, &perms, OP_EXEC, MAY_EXEC, name,
target, new,
cond->uid, info, error);
if (!new || nonewprivs) {
aa_put_label(new);
return ERR_PTR(error);
}
return new;
}
static int profile_onexec(const struct cred *subj_cred,
struct aa_profile *profile, struct aa_label *onexec,
bool stack, const struct linux_binprm *bprm,
char *buffer, struct path_cond *cond,
bool *secure_exec)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
aa_state_t state = rules->file->start[AA_CLASS_FILE];
struct aa_perms perms = {};
const char *xname = NULL, *info = "change_profile onexec";
int error = -EACCES;
AA_BUG(!profile);
AA_BUG(!onexec);
AA_BUG(!bprm);
AA_BUG(!buffer);
if (profile_unconfined(profile)) {
/* change_profile on exec already granted */
/*
* NOTE: Domain transitions from unconfined are allowed
* even when no_new_privs is set because this aways results
* in a further reduction of permissions.
*/
return 0;
}
error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
&xname, &info, profile->disconnected);
if (error) {
if (profile_unconfined(profile) ||
(profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
AA_DEBUG("name lookup ix on error");
error = 0;
}
xname = bprm->filename;
goto audit;
}
/* find exec permissions for name */
state = aa_str_perms(rules->file, state, xname, cond, &perms);
if (!(perms.allow & AA_MAY_ONEXEC)) {
info = "no change_onexec valid for executable";
goto audit;
}
/* test if this exec can be paired with change_profile onexec.
* onexec permission is linked to exec with a standard pairing
* exec\0change_profile
*/
state = aa_dfa_null_transition(rules->file->dfa, state);
error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
state, &perms);
if (error) {
perms.allow &= ~AA_MAY_ONEXEC;
goto audit;
}
if (!(perms.xindex & AA_X_UNSAFE)) {
if (DEBUG_ON) {
dbg_printk("apparmor: scrubbing environment "
"variables for %s label=", xname);
aa_label_printk(onexec, GFP_KERNEL);
dbg_printk("\n");
}
*secure_exec = true;
}
audit:
return aa_audit_file(subj_cred, profile, &perms, OP_EXEC,
AA_MAY_ONEXEC, xname,
NULL, onexec, cond->uid, info, error);
}
/* ensure none ns domain transitions are correctly applied with onexec */
static struct aa_label *handle_onexec(const struct cred *subj_cred,
struct aa_label *label,
struct aa_label *onexec, bool stack,
const struct linux_binprm *bprm,
char *buffer, struct path_cond *cond,
bool *unsafe)
{
struct aa_profile *profile;
struct aa_label *new;
int error;
AA_BUG(!label);
AA_BUG(!onexec);
AA_BUG(!bprm);
AA_BUG(!buffer);
if (!stack) {
error = fn_for_each_in_ns(label, profile,
profile_onexec(subj_cred, profile, onexec, stack,
bprm, buffer, cond, unsafe));
if (error)
return ERR_PTR(error);
new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
aa_get_newest_label(onexec),
profile_transition(subj_cred, profile, bprm,
buffer,
cond, unsafe));
} else {
/* TODO: determine how much we want to loosen this */
error = fn_for_each_in_ns(label, profile,
profile_onexec(subj_cred, profile, onexec, stack, bprm,
buffer, cond, unsafe));
if (error)
return ERR_PTR(error);
new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
aa_label_merge(&profile->label, onexec,
GFP_KERNEL),
profile_transition(subj_cred, profile, bprm,
buffer,
cond, unsafe));
}
if (new)
return new;
/* TODO: get rid of GLOBAL_ROOT_UID */
error = fn_for_each_in_ns(label, profile,
aa_audit_file(subj_cred, profile, &nullperms,
OP_CHANGE_ONEXEC,
AA_MAY_ONEXEC, bprm->filename, NULL,
onexec, GLOBAL_ROOT_UID,
"failed to build target label", -ENOMEM));
return ERR_PTR(error);
}
/**
* apparmor_bprm_creds_for_exec - Update the new creds on the bprm struct
* @bprm: binprm for the exec (NOT NULL)
*
* Returns: %0 or error on failure
*
* TODO: once the other paths are done see if we can't refactor into a fn
*/
int apparmor_bprm_creds_for_exec(struct linux_binprm *bprm)
{
struct aa_task_ctx *ctx;
struct aa_label *label, *new = NULL;
const struct cred *subj_cred;
struct aa_profile *profile;
char *buffer = NULL;
const char *info = NULL;
int error = 0;
bool unsafe = false;
vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(bprm->file),
file_inode(bprm->file));
struct path_cond cond = {
vfsuid_into_kuid(vfsuid),
file_inode(bprm->file)->i_mode
};
subj_cred = current_cred();
ctx = task_ctx(current);
AA_BUG(!cred_label(bprm->cred));
AA_BUG(!ctx);
label = aa_get_newest_label(cred_label(bprm->cred));
/*
* Detect no new privs being set, and store the label it
* occurred under. Ideally this would happen when nnp
* is set but there isn't a good way to do that yet.
*
* Testing for unconfined must be done before the subset test
*/
if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
!ctx->nnp)
ctx->nnp = aa_get_label(label);
/* buffer freed below, name is pointer into buffer */
buffer = aa_get_buffer(false);
if (!buffer) {
error = -ENOMEM;
goto done;
}
/* Test for onexec first as onexec override other x transitions. */
if (ctx->onexec)
new = handle_onexec(subj_cred, label, ctx->onexec, ctx->token,
bprm, buffer, &cond, &unsafe);
else
new = fn_label_build(label, profile, GFP_KERNEL,
profile_transition(subj_cred, profile, bprm,
buffer,
&cond, &unsafe));
AA_BUG(!new);
if (IS_ERR(new)) {
error = PTR_ERR(new);
goto done;
} else if (!new) {
error = -ENOMEM;
goto done;
}
/* Policy has specified a domain transitions. If no_new_privs and
* confined ensure the transition is to confinement that is subset
* of the confinement when the task entered no new privs.
*
* NOTE: Domain transitions from unconfined and to stacked
* subsets are allowed even when no_new_privs is set because this
* aways results in a further reduction of permissions.
*/
if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
!unconfined(label) &&
!aa_label_is_unconfined_subset(new, ctx->nnp)) {
error = -EPERM;
info = "no new privs";
goto audit;
}
if (bprm->unsafe & LSM_UNSAFE_SHARE) {
/* FIXME: currently don't mediate shared state */
;
}
if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
/* TODO: test needs to be profile of label to new */
error = may_change_ptraced_domain(bprm->cred, new, &info);
if (error)
goto audit;
}
if (unsafe) {
if (DEBUG_ON) {
dbg_printk("scrubbing environment variables for %s "
"label=", bprm->filename);
aa_label_printk(new, GFP_KERNEL);
dbg_printk("\n");
}
bprm->secureexec = 1;
}
if (label->proxy != new->proxy) {
/* when transitioning clear unsafe personality bits */
if (DEBUG_ON) {
dbg_printk("apparmor: clearing unsafe personality "
"bits. %s label=", bprm->filename);
aa_label_printk(new, GFP_KERNEL);
dbg_printk("\n");
}
bprm->per_clear |= PER_CLEAR_ON_SETID;
}
aa_put_label(cred_label(bprm->cred));
/* transfer reference, released when cred is freed */
set_cred_label(bprm->cred, new);
done:
aa_put_label(label);
aa_put_buffer(buffer);
return error;
audit:
error = fn_for_each(label, profile,
aa_audit_file(current_cred(), profile, &nullperms,
OP_EXEC, MAY_EXEC,
bprm->filename, NULL, new,
vfsuid_into_kuid(vfsuid), info, error));
aa_put_label(new);
goto done;
}
/*
* Functions for self directed profile change
*/
/* helper fn for change_hat
*
* Returns: label for hat transition OR ERR_PTR. Does NOT return NULL
*/
static struct aa_label *build_change_hat(const struct cred *subj_cred,
struct aa_profile *profile,
const char *name, bool sibling)
{
struct aa_profile *root, *hat = NULL;
const char *info = NULL;
int error = 0;
if (sibling && PROFILE_IS_HAT(profile)) {
root = aa_get_profile_rcu(&profile->parent);
} else if (!sibling && !PROFILE_IS_HAT(profile)) {
root = aa_get_profile(profile);
} else {
info = "conflicting target types";
error = -EPERM;
goto audit;
}
hat = aa_find_child(root, name);
if (!hat) {
error = -ENOENT;
if (COMPLAIN_MODE(profile)) {
hat = aa_new_learning_profile(profile, true, name,
GFP_KERNEL);
if (!hat) {
info = "failed null profile create";
error = -ENOMEM;
}
}
}
aa_put_profile(root);
audit:
aa_audit_file(subj_cred, profile, &nullperms, OP_CHANGE_HAT,
AA_MAY_CHANGEHAT,
name, hat ? hat->base.hname : NULL,
hat ? &hat->label : NULL, GLOBAL_ROOT_UID, info,
error);
if (!hat || (error && error != -ENOENT))
return ERR_PTR(error);
/* if hat && error - complain mode, already audited and we adjust for
* complain mode allow by returning hat->label
*/
return &hat->label;
}
/* helper fn for changing into a hat
*
* Returns: label for hat transition or ERR_PTR. Does not return NULL
*/
static struct aa_label *change_hat(const struct cred *subj_cred,
struct aa_label *label, const char *hats[],
int count, int flags)
{
struct aa_profile *profile, *root, *hat = NULL;
struct aa_label *new;
struct label_it it;
bool sibling = false;
const char *name, *info = NULL;
int i, error;
AA_BUG(!label);
AA_BUG(!hats);
AA_BUG(count < 1);
if (PROFILE_IS_HAT(labels_profile(label)))
sibling = true;
/*find first matching hat */
for (i = 0; i < count && !hat; i++) {
name = hats[i];
label_for_each_in_ns(it, labels_ns(label), label, profile) {
if (sibling && PROFILE_IS_HAT(profile)) {
root = aa_get_profile_rcu(&profile->parent);
} else if (!sibling && !PROFILE_IS_HAT(profile)) {
root = aa_get_profile(profile);
} else { /* conflicting change type */
info = "conflicting targets types";
error = -EPERM;
goto fail;
}
hat = aa_find_child(root, name);
aa_put_profile(root);
if (!hat) {
if (!COMPLAIN_MODE(profile))
goto outer_continue;
/* complain mode succeed as if hat */
} else if (!PROFILE_IS_HAT(hat)) {
info = "target not hat";
error = -EPERM;
aa_put_profile(hat);
goto fail;
}
aa_put_profile(hat);
}
/* found a hat for all profiles in ns */
goto build;
outer_continue:
;
}
/* no hats that match, find appropriate error
*
* In complain mode audit of the failure is based off of the first
* hat supplied. This is done due how userspace interacts with
* change_hat.
*/
name = NULL;
label_for_each_in_ns(it, labels_ns(label), label, profile) {
if (!list_empty(&profile->base.profiles)) {
info = "hat not found";
error = -ENOENT;
goto fail;
}
}
info = "no hats defined";
error = -ECHILD;
fail:
label_for_each_in_ns(it, labels_ns(label), label, profile) {
/*
* no target as it has failed to be found or built
*
* change_hat uses probing and should not log failures
* related to missing hats
*/
/* TODO: get rid of GLOBAL_ROOT_UID */
if (count > 1 || COMPLAIN_MODE(profile)) {
aa_audit_file(subj_cred, profile, &nullperms,
OP_CHANGE_HAT,
AA_MAY_CHANGEHAT, name, NULL, NULL,
GLOBAL_ROOT_UID, info, error);
}
}
return ERR_PTR(error);
build:
new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
build_change_hat(subj_cred, profile, name,
sibling),
aa_get_label(&profile->label));
if (!new) {
info = "label build failed";
error = -ENOMEM;
goto fail;
} /* else if (IS_ERR) build_change_hat has logged error so return new */
return new;
}
/**
* aa_change_hat - change hat to/from subprofile
* @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
* @count: number of hat names in @hats
* @token: magic value to validate the hat change
* @flags: flags affecting behavior of the change
*
* Returns %0 on success, error otherwise.
*
* Change to the first profile specified in @hats that exists, and store
* the @hat_magic in the current task context. If the count == 0 and the
* @token matches that stored in the current task context, return to the
* top level profile.
*
* change_hat only applies to profiles in the current ns, and each profile
* in the ns must make the same transition otherwise change_hat will fail.
*/
int aa_change_hat(const char *hats[], int count, u64 token, int flags)
{
const struct cred *subj_cred;
struct aa_task_ctx *ctx = task_ctx(current);
struct aa_label *label, *previous, *new = NULL, *target = NULL;
struct aa_profile *profile;
struct aa_perms perms = {};
const char *info = NULL;
int error = 0;
/* released below */
subj_cred = get_current_cred();
label = aa_get_newest_cred_label(subj_cred);
previous = aa_get_newest_label(ctx->previous);
/*
* Detect no new privs being set, and store the label it
* occurred under. Ideally this would happen when nnp
* is set but there isn't a good way to do that yet.
*
* Testing for unconfined must be done before the subset test
*/
if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
ctx->nnp = aa_get_label(label);
if (unconfined(label)) {
info = "unconfined can not change_hat";
error = -EPERM;
goto fail;
}
if (count) {
new = change_hat(subj_cred, label, hats, count, flags);
AA_BUG(!new);
if (IS_ERR(new)) {
error = PTR_ERR(new);
new = NULL;
/* already audited */
goto out;
}
/* target cred is the same as current except new label */
error = may_change_ptraced_domain(subj_cred, new, &info);
if (error)
goto fail;
/*
* no new privs prevents domain transitions that would
* reduce restrictions.
*/
if (task_no_new_privs(current) && !unconfined(label) &&
!aa_label_is_unconfined_subset(new, ctx->nnp)) {
/* not an apparmor denial per se, so don't log it */
AA_DEBUG("no_new_privs - change_hat denied");
error = -EPERM;
goto out;
}
if (flags & AA_CHANGE_TEST)
goto out;
target = new;
error = aa_set_current_hat(new, token);
if (error == -EACCES)
/* kill task in case of brute force attacks */
goto kill;
} else if (previous && !(flags & AA_CHANGE_TEST)) {
/*
* no new privs prevents domain transitions that would
* reduce restrictions.
*/
if (task_no_new_privs(current) && !unconfined(label) &&
!aa_label_is_unconfined_subset(previous, ctx->nnp)) {
/* not an apparmor denial per se, so don't log it */
AA_DEBUG("no_new_privs - change_hat denied");
error = -EPERM;
goto out;
}
/* Return to saved label. Kill task if restore fails
* to avoid brute force attacks
*/
target = previous;
error = aa_restore_previous_label(token);
if (error) {
if (error == -EACCES)
goto kill;
goto fail;
}
} /* else ignore @flags && restores when there is no saved profile */
out:
aa_put_label(new);
aa_put_label(previous);
aa_put_label(label);
put_cred(subj_cred);
return error;
kill:
info = "failed token match";
perms.kill = AA_MAY_CHANGEHAT;
fail:
fn_for_each_in_ns(label, profile,
aa_audit_file(subj_cred, profile, &perms, OP_CHANGE_HAT,
AA_MAY_CHANGEHAT, NULL, NULL, target,
GLOBAL_ROOT_UID, info, error));
goto out;
}
static int change_profile_perms_wrapper(const char *op, const char *name,
const struct cred *subj_cred,
struct aa_profile *profile,
struct aa_label *target, bool stack,
u32 request, struct aa_perms *perms)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
const char *info = NULL;
int error = 0;
if (!error)
error = change_profile_perms(profile, target, stack, request,
rules->file->start[AA_CLASS_FILE],
perms);
if (error)
error = aa_audit_file(subj_cred, profile, perms, op, request,
name,
NULL, target, GLOBAL_ROOT_UID, info,
error);
return error;
}
static const char *stack_msg = "change_profile unprivileged unconfined converted to stacking";
/**
* aa_change_profile - perform a one-way profile transition
* @fqname: name of profile may include namespace (NOT NULL)
* @flags: flags affecting change behavior
*
* Change to new profile @name. Unlike with hats, there is no way
* to change back. If @name isn't specified the current profile name is
* used.
* If @onexec then the transition is delayed until
* the next exec.
*
* Returns %0 on success, error otherwise.
*/
int aa_change_profile(const char *fqname, int flags)
{
struct aa_label *label, *new = NULL, *target = NULL;
struct aa_profile *profile;
struct aa_perms perms = {};
const char *info = NULL;
const char *auditname = fqname; /* retain leading & if stack */
bool stack = flags & AA_CHANGE_STACK;
struct aa_task_ctx *ctx = task_ctx(current);
const struct cred *subj_cred = get_current_cred();
int error = 0;
char *op;
u32 request;
label = aa_get_current_label();
/*
* Detect no new privs being set, and store the label it
* occurred under. Ideally this would happen when nnp
* is set but there isn't a good way to do that yet.
*
* Testing for unconfined must be done before the subset test
*/
if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
ctx->nnp = aa_get_label(label);
if (!fqname || !*fqname) {
aa_put_label(label);
AA_DEBUG("no profile name");
return -EINVAL;
}
if (flags & AA_CHANGE_ONEXEC) {
request = AA_MAY_ONEXEC;
if (stack)
op = OP_STACK_ONEXEC;
else
op = OP_CHANGE_ONEXEC;
} else {
request = AA_MAY_CHANGE_PROFILE;
if (stack)
op = OP_STACK;
else
op = OP_CHANGE_PROFILE;
}
/* This should move to a per profile test. Requires pushing build
* into callback
*/
if (!stack && unconfined(label) &&
label == &labels_ns(label)->unconfined->label &&
aa_unprivileged_unconfined_restricted &&
/* TODO: refactor so this check is a fn */
cap_capable(current_cred(), &init_user_ns, CAP_MAC_OVERRIDE,
CAP_OPT_NOAUDIT)) {
/* regardless of the request in this case apparmor
* stacks against unconfined so admin set policy can't be
* by-passed
*/
stack = true;
perms.audit = request;
(void) fn_for_each_in_ns(label, profile,
aa_audit_file(subj_cred, profile, &perms, op,
request, auditname, NULL, target,
GLOBAL_ROOT_UID, stack_msg, 0));
perms.audit = 0;
}
if (*fqname == '&') {
stack = true;
/* don't have label_parse() do stacking */
fqname++;
}
target = aa_label_parse(label, fqname, GFP_KERNEL, true, false);
if (IS_ERR(target)) {
struct aa_profile *tprofile;
info = "label not found";
error = PTR_ERR(target);
target = NULL;
/*
* TODO: fixme using labels_profile is not right - do profile
* per complain profile
*/
if ((flags & AA_CHANGE_TEST) ||
!COMPLAIN_MODE(labels_profile(label)))
goto audit;
/* released below */
tprofile = aa_new_learning_profile(labels_profile(label), false,
fqname, GFP_KERNEL);
if (!tprofile) {
info = "failed null profile create";
error = -ENOMEM;
goto audit;
}
target = &tprofile->label;
goto check;
}
/*
* self directed transitions only apply to current policy ns
* TODO: currently requiring perms for stacking and straight change
* stacking doesn't strictly need this. Determine how much
* we want to loosen this restriction for stacking
*
* if (!stack) {
*/
error = fn_for_each_in_ns(label, profile,
change_profile_perms_wrapper(op, auditname,
subj_cred,
profile, target, stack,
request, &perms));
if (error)
/* auditing done in change_profile_perms_wrapper */
goto out;
/* } */
check:
/* check if tracing task is allowed to trace target domain */
error = may_change_ptraced_domain(subj_cred, target, &info);
if (error && !fn_for_each_in_ns(label, profile,
COMPLAIN_MODE(profile)))
goto audit;
/* TODO: add permission check to allow this
* if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
* info = "not a single threaded task";
* error = -EACCES;
* goto audit;
* }
*/
if (flags & AA_CHANGE_TEST)
goto out;
/* stacking is always a subset, so only check the nonstack case */
if (!stack) {
new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
aa_get_label(target),
aa_get_label(&profile->label));
/*
* no new privs prevents domain transitions that would
* reduce restrictions.
*/
if (task_no_new_privs(current) && !unconfined(label) &&
!aa_label_is_unconfined_subset(new, ctx->nnp)) {
/* not an apparmor denial per se, so don't log it */
AA_DEBUG("no_new_privs - change_hat denied");
error = -EPERM;
goto out;
}
}
if (!(flags & AA_CHANGE_ONEXEC)) {
/* only transition profiles in the current ns */
if (stack)
new = aa_label_merge(label, target, GFP_KERNEL);
if (IS_ERR_OR_NULL(new)) {
info = "failed to build target label";
if (!new)
error = -ENOMEM;
else
error = PTR_ERR(new);
new = NULL;
perms.allow = 0;
goto audit;
}
error = aa_replace_current_label(new);
} else {
if (new) {
aa_put_label(new);
new = NULL;
}
/* full transition will be built in exec path */
aa_set_current_onexec(target, stack);
}
audit:
error = fn_for_each_in_ns(label, profile,
aa_audit_file(subj_cred,
profile, &perms, op, request, auditname,
NULL, new ? new : target,
GLOBAL_ROOT_UID, info, error));
out:
aa_put_label(new);
aa_put_label(target);
aa_put_label(label);
put_cred(subj_cred);
return error;
}
Codebase Browser
linux