Commit 93c98a48 authored by John Johansen's avatar John Johansen

apparmor: move exec domain mediation to using labels

Signed-off-by: default avatarJohn Johansen <john.johansen@canonical.com>
parent 5379a331
...@@ -87,42 +87,236 @@ static int may_change_ptraced_domain(struct aa_label *to_label, ...@@ -87,42 +87,236 @@ static int may_change_ptraced_domain(struct aa_label *to_label,
return error; 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 unsigned int match_component(struct aa_profile *profile,
struct aa_profile *tp,
bool stack, unsigned int state)
{
const char *ns_name;
if (stack)
state = aa_dfa_match(profile->file.dfa, state, "&");
if (profile->ns == tp->ns)
return aa_dfa_match(profile->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(profile->file.dfa, state, ":", 1);
state = aa_dfa_match(profile->file.dfa, state, ns_name);
state = aa_dfa_match_len(profile->file.dfa, state, ":", 1);
return aa_dfa_match(profile->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
* @start: 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,
unsigned int state, bool subns, u32 request,
struct aa_perms *perms)
{
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(profile->file.dfa, state, "//&");
state = match_component(profile, tp, false, state);
if (!state)
goto fail;
}
*perms = aa_compute_fperms(profile->file.dfa, 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,
unsigned int start, bool subns, u32 request,
struct aa_perms *perms)
{
struct aa_profile *tp;
struct label_it i;
struct aa_perms tmp;
struct path_cond cond = { };
unsigned int 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_compute_fperms(profile->file.dfa, 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_compute_fperms(profile->file.dfa, 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, unsigned int 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 * change_profile_perms - find permissions for change_profile
* @profile: the current profile (NOT NULL) * @profile: the current profile (NOT NULL)
* @ns: the namespace being switched to (NOT NULL) * @target: label to transition to (NOT NULL)
* @name: the name of the profile to change to (NOT NULL) * @stack: whether this is a stacking request
* @request: requested perms * @request: requested perms
* @start: state to start matching in * @start: state to start matching in
* *
*
* Returns: permission set * 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 struct aa_perms change_profile_perms(struct aa_profile *profile, static int change_profile_perms(struct aa_profile *profile,
struct aa_ns *ns, struct aa_label *target, bool stack,
const char *name, u32 request, u32 request, unsigned int start,
unsigned int 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);
}
static struct aa_perms change_profile_perms_wrapper(struct aa_profile *profile,
struct aa_profile *target,
u32 request,
unsigned int start)
{ {
struct aa_perms perms; struct aa_perms perms;
struct path_cond cond = { };
unsigned int state;
if (profile_unconfined(profile)) { if (profile_unconfined(profile)) {
perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC; perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC;
perms.audit = perms.quiet = perms.kill = 0; perms.audit = perms.quiet = perms.kill = 0;
return perms; return perms;
} else if (!profile->file.dfa) {
return nullperms;
} else if ((ns == profile->ns)) {
/* try matching against rules with out namespace prepended */
aa_str_perms(profile->file.dfa, start, name, &cond, &perms);
if (COMBINED_PERM_MASK(perms) & request)
return perms;
} }
/* try matching with namespace name and then profile */ if (change_profile_perms(profile, &target->label, false, request,
state = aa_dfa_match(profile->file.dfa, start, ns->base.name); start, &perms))
state = aa_dfa_match_len(profile->file.dfa, state, ":", 1); return nullperms;
aa_str_perms(profile->file.dfa, state, name, &cond, &perms);
return perms; return perms;
} }
...@@ -173,10 +367,10 @@ static struct aa_profile *__attach_match(const char *name, ...@@ -173,10 +367,10 @@ static struct aa_profile *__attach_match(const char *name,
* @list: list to search (NOT NULL) * @list: list to search (NOT NULL)
* @name: the executable name to match against (NOT NULL) * @name: the executable name to match against (NOT NULL)
* *
* Returns: profile or NULL if no match found * Returns: label or NULL if no match found
*/ */
static struct aa_profile *find_attach(struct aa_ns *ns, static struct aa_label *find_attach(struct aa_ns *ns, struct list_head *list,
struct list_head *list, const char *name) const char *name)
{ {
struct aa_profile *profile; struct aa_profile *profile;
...@@ -184,49 +378,7 @@ static struct aa_profile *find_attach(struct aa_ns *ns, ...@@ -184,49 +378,7 @@ static struct aa_profile *find_attach(struct aa_ns *ns,
profile = aa_get_profile(__attach_match(name, list)); profile = aa_get_profile(__attach_match(name, list));
rcu_read_unlock(); rcu_read_unlock();
return profile; return profile ? &profile->label : NULL;
}
/**
* separate_fqname - separate the namespace and profile names
* @fqname: the fqname name to split (NOT NULL)
* @ns_name: the namespace name if it exists (NOT NULL)
*
* This is the xtable equivalent routine of aa_split_fqname. It finds the
* split in an xtable fqname which contains an embedded \0 instead of a :
* if a namespace is specified. This is done so the xtable is constant and
* isn't re-split on every lookup.
*
* Either the profile or namespace name may be optional but if the namespace
* is specified the profile name termination must be present. This results
* in the following possible encodings:
* profile_name\0
* :ns_name\0profile_name\0
* :ns_name\0\0
*
* NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table
*
* Returns: profile name if it is specified else NULL
*/
static const char *separate_fqname(const char *fqname, const char **ns_name)
{
const char *name;
if (fqname[0] == ':') {
/* In this case there is guaranteed to be two \0 terminators
* in the string. They are verified at load time by
* by unpack_trans_table
*/
*ns_name = fqname + 1; /* skip : */
name = *ns_name + strlen(*ns_name) + 1;
if (!*name)
name = NULL;
} else {
*ns_name = NULL;
name = fqname;
}
return name;
} }
static const char *next_name(int xtype, const char *name) static const char *next_name(int xtype, const char *name)
...@@ -238,295 +390,477 @@ static const char *next_name(int xtype, const char *name) ...@@ -238,295 +390,477 @@ static const char *next_name(int xtype, const char *name)
* x_table_lookup - lookup an x transition name via transition table * x_table_lookup - lookup an x transition name via transition table
* @profile: current profile (NOT NULL) * @profile: current profile (NOT NULL)
* @xindex: index into x transition table * @xindex: index into x transition table
* @name: returns: name tested to find label (NOT NULL)
* *
* Returns: refcounted profile, or NULL on failure (MAYBE NULL) * Returns: refcounted label, or NULL on failure (MAYBE NULL)
*/ */
static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex) static struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
const char **name)
{ {
struct aa_profile *new_profile = NULL; struct aa_label *label = NULL;
struct aa_ns *ns = profile->ns;
u32 xtype = xindex & AA_X_TYPE_MASK; u32 xtype = xindex & AA_X_TYPE_MASK;
int index = xindex & AA_X_INDEX_MASK; int index = xindex & AA_X_INDEX_MASK;
const char *name;
/* index is guaranteed to be in range, validated at load time */ AA_BUG(!name);
for (name = profile->file.trans.table[index]; !new_profile && name;
name = next_name(xtype, name)) {
struct aa_ns *new_ns;
const char *xname = NULL;
new_ns = NULL; /* 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 = profile->file.trans.table[index]; !label && *name;
*name = next_name(xtype, *name)) {
if (xindex & AA_X_CHILD) { if (xindex & AA_X_CHILD) {
struct aa_profile *new_profile;
/* release by caller */ /* release by caller */
new_profile = aa_find_child(profile, name); new_profile = aa_find_child(profile, *name);
if (new_profile)
label = &new_profile->label;
continue; continue;
} else if (*name == ':') {
/* switching namespace */
const char *ns_name;
xname = name = separate_fqname(name, &ns_name);
if (!xname)
/* no name so use profile name */
xname = profile->base.hname;
if (*ns_name == '@') {
/* TODO: variable support */
;
}
/* released below */
new_ns = aa_find_ns(ns, ns_name);
if (!new_ns)
continue;
} else if (*name == '@') {
/* TODO: variable support */
continue;
} else {
/* basic namespace lookup */
xname = name;
} }
label = aa_label_parse(&profile->label, *name, GFP_ATOMIC,
/* released by caller */ true, false);
new_profile = aa_lookup_profile(new_ns ? new_ns : ns, xname); if (IS_ERR(label))
aa_put_ns(new_ns); label = NULL;
} }
/* released by caller */ /* released by caller */
return new_profile;
return label;
} }
/** /**
* x_to_profile - get target profile for a given xindex * x_to_label - get target label for a given xindex
* @profile: current profile (NOT NULL) * @profile: current profile (NOT NULL)
* @name: name to lookup (NOT NULL) * @name: name to lookup (NOT NULL)
* @xindex: index into x transition table * @xindex: index into x transition table
* @lookupname: returns: name used in lookup if one was specified (NOT NULL)
* *
* find profile for a transition index * find label for a transition index
* *
* Returns: refcounted profile or NULL if not found available * Returns: refcounted label or NULL if not found available
*/ */
static struct aa_profile *x_to_profile(struct aa_profile *profile, static struct aa_label *x_to_label(struct aa_profile *profile,
const char *name, u32 xindex) const char *name, u32 xindex,
const char **lookupname,
const char **info)
{ {
struct aa_profile *new_profile = NULL; struct aa_label *new = NULL;
struct aa_ns *ns = profile->ns; struct aa_ns *ns = profile->ns;
u32 xtype = xindex & AA_X_TYPE_MASK; u32 xtype = xindex & AA_X_TYPE_MASK;
const char *stack = NULL;
switch (xtype) { switch (xtype) {
case AA_X_NONE: case AA_X_NONE:
/* fail exec unless ix || ux fallback - handled by caller */ /* fail exec unless ix || ux fallback - handled by caller */
return NULL; *lookupname = NULL;
break;
case AA_X_TABLE:
/* TODO: fix when perm mapping done at unload */
stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
if (*stack != '&') {
/* released by caller */
new = x_table_lookup(profile, xindex, lookupname);
stack = NULL;
break;
}
/* fall through to X_NAME */
case AA_X_NAME: case AA_X_NAME:
if (xindex & AA_X_CHILD) if (xindex & AA_X_CHILD)
/* released by caller */ /* released by caller */
new_profile = find_attach(ns, &profile->base.profiles, new = find_attach(ns, &profile->base.profiles,
name); name);
else else
/* released by caller */ /* released by caller */
new_profile = find_attach(ns, &ns->base.profiles, new = find_attach(ns, &ns->base.profiles,
name); name);
break; *lookupname = name;
case AA_X_TABLE:
/* released by caller */
new_profile = x_table_lookup(profile, xindex);
break; 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_ATOMIC, true, false);
if (IS_ERR(new))
new = NULL;
aa_put_label(base);
}
/* released by caller */ /* released by caller */
return new_profile; return new;
} }
/** static struct aa_label *profile_transition(struct aa_profile *profile,
* apparmor_bprm_set_creds - set the new creds on the bprm struct const struct linux_binprm *bprm,
* @bprm: binprm for the exec (NOT NULL) char *buffer, struct path_cond *cond,
* bool *secure_exec)
* Returns: %0 or error on failure
*/
int apparmor_bprm_set_creds(struct linux_binprm *bprm)
{ {
struct aa_task_ctx *ctx; struct aa_label *new = NULL;
struct aa_label *label; const char *info = NULL, *name = NULL, *target = NULL;
struct aa_profile *profile, *new_profile = NULL; unsigned int state = profile->file.start;
struct aa_ns *ns;
char *buffer = NULL;
unsigned int state;
struct aa_perms perms = {}; struct aa_perms perms = {};
struct path_cond cond = { bool nonewprivs = false;
file_inode(bprm->file)->i_uid,
file_inode(bprm->file)->i_mode
};
const char *name = NULL, *info = NULL;
int error = 0; int error = 0;
if (bprm->cred_prepared) AA_BUG(!profile);
return 0; AA_BUG(!bprm);
AA_BUG(!buffer);
ctx = cred_ctx(bprm->cred);
AA_BUG(!ctx);
label = aa_get_newest_label(ctx->label);
profile = labels_profile(label);
/* buffer freed below, name is pointer into buffer */
get_buffers(buffer);
/*
* get the namespace from the replacement profile as replacement
* can change the namespace
*/
ns = profile->ns;
state = profile->file.start;
error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer, error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
&name, &info, profile->disconnected); &name, &info, profile->disconnected);
if (error) { if (error) {
if (profile_unconfined(profile) || if (profile_unconfined(profile) ||
(profile->label.flags & FLAG_IX_ON_NAME_ERROR)) (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
AA_DEBUG("name lookup ix on error");
error = 0; error = 0;
new = aa_get_newest_label(&profile->label);
}
name = bprm->filename; name = bprm->filename;
goto audit; goto audit;
} }
/* Test for onexec first as onexec directives override other
* x transitions.
*/
if (profile_unconfined(profile)) { if (profile_unconfined(profile)) {
/* unconfined task */ new = find_attach(profile->ns, &profile->ns->base.profiles,
if (ctx->onexec) name);
/* change_profile on exec already been granted */ if (new) {
new_profile = labels_profile(aa_get_label(ctx->onexec)); AA_DEBUG("unconfined attached to new label");
else return new;
new_profile = find_attach(ns, &ns->base.profiles, name); }
if (!new_profile) AA_DEBUG("unconfined exec no attachment");
goto cleanup; return aa_get_newest_label(&profile->label);
/*
* NOTE: Domain transitions from unconfined are allowed
* even when no_new_privs is set because this aways results
* in a further reduction of permissions.
*/
goto apply;
} }
/* find exec permissions for name */ /* find exec permissions for name */
state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms); state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
if (ctx->onexec) {
struct aa_perms cp;
info = "change_profile onexec";
new_profile = labels_profile(aa_get_newest_label(ctx->onexec));
if (!(perms.allow & AA_MAY_ONEXEC))
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(profile->file.dfa, state);
cp = change_profile_perms(profile, labels_ns(ctx->onexec),
labels_profile(ctx->onexec)->base.name,
AA_MAY_ONEXEC, state);
if (!(cp.allow & AA_MAY_ONEXEC))
goto audit;
goto apply;
}
if (perms.allow & MAY_EXEC) { if (perms.allow & MAY_EXEC) {
/* exec permission determine how to transition */ /* exec permission determine how to transition */
new_profile = x_to_profile(profile, name, perms.xindex); new = x_to_label(profile, name, perms.xindex, &target, &info);
if (!new_profile) { if (new && new->proxy == profile->label.proxy && info) {
if (perms.xindex & AA_X_INHERIT) { /* hack ix fallback - improve how this is detected */
/* (p|c|n)ix - don't change profile but do goto audit;
* use the newest version, which was picked } else if (!new) {
* up above when getting profile error = -EACCES;
*/ info = "profile transition not found";
info = "ix fallback"; /* remove MAY_EXEC to audit as failure */
new_profile = aa_get_profile(profile); perms.allow &= ~MAY_EXEC;
goto x_clear;
} else if (perms.xindex & AA_X_UNCONFINED) {
new_profile = aa_get_newest_profile(ns->unconfined);
info = "ux fallback";
} else {
error = -EACCES;
info = "profile not found";
/* remove MAY_EXEC to audit as failure */
perms.allow &= ~MAY_EXEC;
}
} }
} else if (COMPLAIN_MODE(profile)) { } else if (COMPLAIN_MODE(profile)) {
/* no exec permission - are we in learning mode */ /* no exec permission - learning mode */
new_profile = aa_new_null_profile(profile, false, name, struct aa_profile *new_profile = aa_new_null_profile(profile,
GFP_ATOMIC); false, name,
GFP_ATOMIC);
if (!new_profile) { if (!new_profile) {
error = -ENOMEM; error = -ENOMEM;
info = "could not create null profile"; info = "could not create null profile";
} else } else {
error = -EACCES; error = -EACCES;
new = &new_profile->label;
}
perms.xindex |= AA_X_UNSAFE; perms.xindex |= AA_X_UNSAFE;
} else } else
/* fail exec */ /* fail exec */
error = -EACCES; error = -EACCES;
/* if (!new)
* Policy has specified a domain transition, if no_new_privs then goto audit;
* fail the exec.
/* Policy has specified a domain transitions. if no_new_privs and
* confined and not transitioning to the current domain fail.
*
* NOTE: Domain transitions from unconfined and to stritly 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) { if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
!profile_unconfined(profile) &&
!aa_label_is_subset(new, &profile->label)) {
error = -EPERM; error = -EPERM;
goto cleanup; info = "no new privs";
nonewprivs = true;
perms.allow &= ~MAY_EXEC;
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_ATOMIC);
dbg_printk("\n");
}
*secure_exec = true;
} }
if (!new_profile) audit:
aa_audit_file(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(struct aa_profile *profile, struct aa_label *onexec,
bool stack, const struct linux_binprm *bprm,
char *buffer, struct path_cond *cond,
bool *secure_exec)
{
unsigned int state = profile->file.start;
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; goto audit;
}
/* find exec permissions for name */
state = aa_str_perms(profile->file.dfa, 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(profile->file.dfa, state);
error = change_profile_perms(profile, onexec, stack, AA_MAY_ONEXEC,
state, &perms);
if (error) {
perms.allow &= ~AA_MAY_ONEXEC;
goto audit;
}
/* Policy has specified a domain transitions. if no_new_privs and
* confined and not transitioning to the current domain fail.
*
* NOTE: Domain transitions from unconfined and to stritly 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) &&
!profile_unconfined(profile) &&
!aa_label_is_subset(onexec, &profile->label)) {
error = -EPERM;
info = "no new privs";
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_ATOMIC);
dbg_printk("\n");
}
*secure_exec = true;
}
audit:
return aa_audit_file(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(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(profile, onexec, stack,
bprm, buffer, cond, unsafe));
if (error)
return ERR_PTR(error);
new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
aa_get_newest_label(onexec),
profile_transition(profile, bprm, buffer,
cond, unsafe));
} else {
/* TODO: determine how much we want to losen this */
error = fn_for_each_in_ns(label, profile,
profile_onexec(profile, onexec, stack, bprm,
buffer, cond, unsafe));
if (error)
return ERR_PTR(error);
new = fn_label_build_in_ns(label, profile, GFP_ATOMIC,
aa_label_merge(&profile->label, onexec,
GFP_ATOMIC),
profile_transition(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(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_set_creds - set 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_set_creds(struct linux_binprm *bprm)
{
struct aa_task_ctx *ctx;
struct aa_label *label, *new = NULL;
struct aa_profile *profile;
char *buffer = NULL;
const char *info = NULL;
int error = 0;
bool unsafe = false;
struct path_cond cond = {
file_inode(bprm->file)->i_uid,
file_inode(bprm->file)->i_mode
};
if (bprm->cred_prepared)
return 0;
ctx = cred_ctx(bprm->cred);
AA_BUG(!ctx);
label = aa_get_newest_label(ctx->label);
/* buffer freed below, name is pointer into buffer */
get_buffers(buffer);
/* Test for onexec first as onexec override other x transitions. */
if (ctx->onexec)
new = handle_onexec(label, ctx->onexec, ctx->token,
bprm, buffer, &cond, &unsafe);
else
new = fn_label_build(label, profile, GFP_ATOMIC,
profile_transition(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;
}
/* TODO: Add ns level no_new_privs subset test */
if (bprm->unsafe & LSM_UNSAFE_SHARE) { if (bprm->unsafe & LSM_UNSAFE_SHARE) {
/* FIXME: currently don't mediate shared state */ /* FIXME: currently don't mediate shared state */
; ;
} }
if (bprm->unsafe & LSM_UNSAFE_PTRACE) { if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
error = may_change_ptraced_domain(&new_profile->label, &info); /* TODO: test needs to be profile of label to new */
error = may_change_ptraced_domain(new, &info);
if (error) if (error)
goto audit; goto audit;
} }
/* Determine if secure exec is needed. if (unsafe) {
* Can be at this point for the following reasons: if (DEBUG_ON) {
* 1. unconfined switching to confined dbg_printk("scrubbing environment variables for %s "
* 2. confined switching to different confinement "label=", bprm->filename);
* 3. confined switching to unconfined aa_label_printk(new, GFP_ATOMIC);
* dbg_printk("\n");
* Cases 2 and 3 are marked as requiring secure exec }
* (unless policy specified "unsafe exec")
*
* bprm->unsafe is used to cache the AA_X_UNSAFE permission
* to avoid having to recompute in secureexec
*/
if (!(perms.xindex & AA_X_UNSAFE)) {
AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
name, new_profile->base.hname);
bprm->unsafe |= AA_SECURE_X_NEEDED; bprm->unsafe |= AA_SECURE_X_NEEDED;
} }
apply:
/* when transitioning profiles clear unsafe personality bits */
bprm->per_clear |= PER_CLEAR_ON_SETID;
x_clear: 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_ATOMIC);
dbg_printk("\n");
}
bprm->per_clear |= PER_CLEAR_ON_SETID;
}
aa_put_label(ctx->label); aa_put_label(ctx->label);
/* transfer new profile reference will be released when ctx is freed */ /* transfer reference, released when ctx is freed */
ctx->label = &new_profile->label; ctx->label = new;
new_profile = NULL;
/* clear out all temporary/transitional state from the context */ done:
/* clear out temporary/transitional state from the context */
aa_clear_task_ctx_trans(ctx); aa_clear_task_ctx_trans(ctx);
audit:
error = aa_audit_file(profile, &perms, OP_EXEC, MAY_EXEC, name,
new_profile ? new_profile->base.hname : NULL,
new_profile ? &new_profile->label : NULL,
cond.uid, info, error);
cleanup:
aa_put_profile(new_profile);
aa_put_label(label); aa_put_label(label);
put_buffers(buffer); put_buffers(buffer);
return error; return error;
audit:
error = fn_for_each(label, profile,
aa_audit_file(profile, &nullperms, OP_EXEC, MAY_EXEC,
bprm->filename, NULL, new,
file_inode(bprm->file)->i_uid, info,
error));
aa_put_label(new);
goto done;
} }
/** /**
...@@ -778,8 +1112,8 @@ int aa_change_profile(const char *fqname, int flags) ...@@ -778,8 +1112,8 @@ int aa_change_profile(const char *fqname, int flags)
} }
} }
perms = change_profile_perms(profile, target->ns, target->base.hname, perms = change_profile_perms_wrapper(profile, target, request,
request, profile->file.start); profile->file.start);
if (!(perms.allow & request)) { if (!(perms.allow & request)) {
error = -EACCES; error = -EACCES;
goto audit; goto audit;
......
...@@ -211,4 +211,89 @@ bool aa_policy_init(struct aa_policy *policy, const char *prefix, ...@@ -211,4 +211,89 @@ bool aa_policy_init(struct aa_policy *policy, const char *prefix,
const char *name, gfp_t gfp); const char *name, gfp_t gfp);
void aa_policy_destroy(struct aa_policy *policy); void aa_policy_destroy(struct aa_policy *policy);
#endif /* AA_LIB_H */
/*
* fn_label_build - abstract out the build of a label transition
* @L: label the transition is being computed for
* @P: profile parameter derived from L by this macro, can be passed to FN
* @GFP: memory allocation type to use
* @FN: fn to call for each profile transition. @P is set to the profile
*
* Returns: new label on success
* ERR_PTR if build @FN fails
* NULL if label_build fails due to low memory conditions
*
* @FN must return a label or ERR_PTR on failure. NULL is not allowed
*/
#define fn_label_build(L, P, GFP, FN) \
({ \
__label__ __cleanup, __done; \
struct aa_label *__new_; \
\
if ((L)->size > 1) { \
/* TODO: add cache of transitions already done */ \
struct label_it __i; \
int __j, __k, __count; \
DEFINE_VEC(label, __lvec); \
DEFINE_VEC(profile, __pvec); \
if (vec_setup(label, __lvec, (L)->size, (GFP))) { \
__new_ = NULL; \
goto __done; \
} \
__j = 0; \
label_for_each(__i, (L), (P)) { \
__new_ = (FN); \
AA_BUG(!__new_); \
if (IS_ERR(__new_)) \
goto __cleanup; \
__lvec[__j++] = __new_; \
} \
for (__j = __count = 0; __j < (L)->size; __j++) \
__count += __lvec[__j]->size; \
if (!vec_setup(profile, __pvec, __count, (GFP))) { \
for (__j = __k = 0; __j < (L)->size; __j++) { \
label_for_each(__i, __lvec[__j], (P)) \
__pvec[__k++] = aa_get_profile(P); \
} \
__count -= aa_vec_unique(__pvec, __count, 0); \
if (__count > 1) { \
__new_ = aa_vec_find_or_create_label(__pvec,\
__count, (GFP)); \
/* only fails if out of Mem */ \
if (!__new_) \
__new_ = NULL; \
} else \
__new_ = aa_get_label(&__pvec[0]->label); \
vec_cleanup(profile, __pvec, __count); \
} else \
__new_ = NULL; \
__cleanup: \
vec_cleanup(label, __lvec, (L)->size); \
} else { \
(P) = labels_profile(L); \
__new_ = (FN); \
} \
__done: \
if (!__new_) \
AA_DEBUG("label build failed\n"); \
(__new_); \
})
#define __fn_build_in_ns(NS, P, NS_FN, OTHER_FN) \
({ \
struct aa_label *__new; \
if ((P)->ns != (NS)) \
__new = (OTHER_FN); \
else \
__new = (NS_FN); \
(__new); \
})
#define fn_label_build_in_ns(L, P, GFP, NS_FN, OTHER_FN) \
({ \
fn_label_build((L), (P), (GFP), \
__fn_build_in_ns(labels_ns(L), (P), (NS_FN), (OTHER_FN))); \
})
#endif /* __AA_LIB_H */
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment