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apparmor: move change_hat mediation to using labels
Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen
parent
93c98a484c
commit
89dbf1962a
1 changed files with 201 additions and 102 deletions
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@ -884,19 +884,153 @@ int apparmor_bprm_secureexec(struct linux_binprm *bprm)
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* Functions for self directed profile change
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*/
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/**
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* new_compound_name - create an hname with @n2 appended to @n1
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* @n1: base of hname (NOT NULL)
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* @n2: name to append (NOT NULL)
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/* helper fn for change_hat
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*
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* Returns: new name or NULL on error
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* Returns: label for hat transition OR ERR_PTR. Does NOT return NULL
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*/
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static char *new_compound_name(const char *n1, const char *n2)
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static struct aa_label *build_change_hat(struct aa_profile *profile,
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const char *name, bool sibling)
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{
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char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL);
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if (name)
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sprintf(name, "%s//%s", n1, n2);
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return name;
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struct aa_profile *root, *hat = NULL;
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const char *info = NULL;
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int error = 0;
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if (sibling && PROFILE_IS_HAT(profile)) {
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root = aa_get_profile_rcu(&profile->parent);
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} else if (!sibling && !PROFILE_IS_HAT(profile)) {
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root = aa_get_profile(profile);
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} else {
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info = "conflicting target types";
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error = -EPERM;
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goto audit;
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}
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hat = aa_find_child(root, name);
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if (!hat) {
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error = -ENOENT;
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if (COMPLAIN_MODE(profile)) {
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hat = aa_new_null_profile(profile, true, name,
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GFP_KERNEL);
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if (!hat) {
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info = "failed null profile create";
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error = -ENOMEM;
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}
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}
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}
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aa_put_profile(root);
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audit:
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aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT,
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name, hat ? hat->base.hname : NULL,
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hat ? &hat->label : NULL, GLOBAL_ROOT_UID, NULL,
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error);
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if (!hat || (error && error != -ENOENT))
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return ERR_PTR(error);
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/* if hat && error - complain mode, already audited and we adjust for
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* complain mode allow by returning hat->label
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*/
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return &hat->label;
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}
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/* helper fn for changing into a hat
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*
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* Returns: label for hat transition or ERR_PTR. Does not return NULL
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*/
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static struct aa_label *change_hat(struct aa_label *label, const char *hats[],
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int count, int flags)
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{
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struct aa_profile *profile, *root, *hat = NULL;
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struct aa_label *new;
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struct label_it it;
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bool sibling = false;
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const char *name, *info = NULL;
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int i, error;
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AA_BUG(!label);
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AA_BUG(!hats);
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AA_BUG(count < 1);
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if (PROFILE_IS_HAT(labels_profile(label)))
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sibling = true;
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/*find first matching hat */
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for (i = 0; i < count && !hat; i++) {
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name = hats[i];
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label_for_each_in_ns(it, labels_ns(label), label, profile) {
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if (sibling && PROFILE_IS_HAT(profile)) {
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root = aa_get_profile_rcu(&profile->parent);
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} else if (!sibling && !PROFILE_IS_HAT(profile)) {
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root = aa_get_profile(profile);
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} else { /* conflicting change type */
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info = "conflicting targets types";
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error = -EPERM;
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goto fail;
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}
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hat = aa_find_child(root, name);
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aa_put_profile(root);
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if (!hat) {
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if (!COMPLAIN_MODE(profile))
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goto outer_continue;
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/* complain mode succeed as if hat */
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} else if (!PROFILE_IS_HAT(hat)) {
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info = "target not hat";
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error = -EPERM;
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aa_put_profile(hat);
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goto fail;
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}
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aa_put_profile(hat);
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}
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/* found a hat for all profiles in ns */
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goto build;
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outer_continue:
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;
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}
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/* no hats that match, find appropriate error
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*
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* In complain mode audit of the failure is based off of the first
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* hat supplied. This is done due how userspace interacts with
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* change_hat.
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*/
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name = NULL;
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label_for_each_in_ns(it, labels_ns(label), label, profile) {
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if (!list_empty(&profile->base.profiles)) {
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info = "hat not found";
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error = -ENOENT;
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goto fail;
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}
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}
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info = "no hats defined";
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error = -ECHILD;
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fail:
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label_for_each_in_ns(it, labels_ns(label), label, profile) {
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/*
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* no target as it has failed to be found or built
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*
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* change_hat uses probing and should not log failures
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* related to missing hats
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*/
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/* TODO: get rid of GLOBAL_ROOT_UID */
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if (count > 1 || COMPLAIN_MODE(profile)) {
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aa_audit_file(profile, &nullperms, OP_CHANGE_HAT,
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AA_MAY_CHANGEHAT, name, NULL, NULL,
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GLOBAL_ROOT_UID, info, error);
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}
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}
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return ERR_PTR(error);
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build:
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new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
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build_change_hat(profile, name, sibling),
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aa_get_label(&profile->label));
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if (!new) {
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info = "label build failed";
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error = -ENOMEM;
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goto fail;
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} /* else if (IS_ERR) build_change_hat has logged error so return new */
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return new;
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}
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/**
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@ -906,23 +1040,24 @@ static char *new_compound_name(const char *n1, const char *n2)
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* @token: magic value to validate the hat change
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* @flags: flags affecting behavior of the change
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*
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* Returns %0 on success, error otherwise.
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*
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* Change to the first profile specified in @hats that exists, and store
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* the @hat_magic in the current task context. If the count == 0 and the
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* @token matches that stored in the current task context, return to the
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* top level profile.
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*
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* Returns %0 on success, error otherwise.
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* change_hat only applies to profiles in the current ns, and each profile
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* in the ns must make the same transition otherwise change_hat will fail.
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*/
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int aa_change_hat(const char *hats[], int count, u64 token, int flags)
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{
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const struct cred *cred;
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struct aa_task_ctx *ctx;
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struct aa_label *label, *previous_label;
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struct aa_profile *profile, *hat = NULL;
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char *name = NULL;
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int i;
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struct aa_label *label, *previous, *new = NULL, *target = NULL;
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struct aa_profile *profile;
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struct aa_perms perms = {};
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const char *target = NULL, *info = NULL;
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const char *info = NULL;
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int error = 0;
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/*
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@ -930,118 +1065,82 @@ int aa_change_hat(const char *hats[], int count, u64 token, int flags)
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* There is no exception for unconfined as change_hat is not
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* available.
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*/
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if (task_no_new_privs(current))
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if (task_no_new_privs(current)) {
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/* not an apparmor denial per se, so don't log it */
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AA_DEBUG("no_new_privs - change_hat denied");
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return -EPERM;
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}
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/* released below */
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cred = get_current_cred();
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ctx = cred_ctx(cred);
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label = aa_get_newest_cred_label(cred);
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previous_label = aa_get_newest_label(ctx->previous);
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profile = labels_profile(label);
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previous = aa_get_newest_label(ctx->previous);
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if (unconfined(label)) {
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info = "unconfined";
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info = "unconfined can not change_hat";
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error = -EPERM;
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goto audit;
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goto fail;
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}
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if (count) {
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/* attempting to change into a new hat or switch to a sibling */
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struct aa_profile *root;
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if (PROFILE_IS_HAT(profile))
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root = aa_get_profile_rcu(&profile->parent);
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else
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root = aa_get_profile(profile);
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/* find first matching hat */
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for (i = 0; i < count && !hat; i++)
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/* released below */
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hat = aa_find_child(root, hats[i]);
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if (!hat) {
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if (!COMPLAIN_MODE(root) || (flags & AA_CHANGE_TEST)) {
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if (list_empty(&root->base.profiles))
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error = -ECHILD;
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else
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error = -ENOENT;
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aa_put_profile(root);
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new = change_hat(label, hats, count, flags);
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AA_BUG(!new);
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if (IS_ERR(new)) {
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error = PTR_ERR(new);
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new = NULL;
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/* already audited */
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goto out;
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}
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/*
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* In complain mode and failed to match any hats.
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* Audit the failure is based off of the first hat
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* supplied. This is done due how userspace
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* interacts with change_hat.
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*
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* TODO: Add logging of all failed hats
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*/
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error = may_change_ptraced_domain(new, &info);
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if (error)
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goto fail;
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/* freed below */
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name = new_compound_name(root->base.hname, hats[0]);
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aa_put_profile(root);
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target = name;
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/* released below */
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hat = aa_new_null_profile(profile, true, hats[0],
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GFP_KERNEL);
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if (!hat) {
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info = "failed null profile create";
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error = -ENOMEM;
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goto audit;
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}
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} else {
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aa_put_profile(root);
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target = hat->base.hname;
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if (!PROFILE_IS_HAT(hat)) {
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info = "target not hat";
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error = -EPERM;
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goto audit;
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}
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}
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if (flags & AA_CHANGE_TEST)
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goto out;
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error = may_change_ptraced_domain(&hat->label, &info);
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if (error) {
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info = "ptraced";
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error = -EPERM;
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goto audit;
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}
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if (!(flags & AA_CHANGE_TEST)) {
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error = aa_set_current_hat(&hat->label, token);
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target = new;
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error = aa_set_current_hat(new, token);
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if (error == -EACCES)
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/* kill task in case of brute force attacks */
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perms.kill = AA_MAY_CHANGEHAT;
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else if (name && !error)
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/* reset error for learning of new hats */
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error = -ENOENT;
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}
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} else if (previous_label) {
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/* Return to saved profile. Kill task if restore fails
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goto kill;
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} else if (previous && !(flags & AA_CHANGE_TEST)) {
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/* Return to saved label. Kill task if restore fails
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* to avoid brute force attacks
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*/
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target = previous_label->hname;
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target = previous;
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error = aa_restore_previous_label(token);
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perms.kill = AA_MAY_CHANGEHAT;
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} else
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/* ignore restores when there is no saved profile */
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goto out;
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audit:
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if (!(flags & AA_CHANGE_TEST))
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error = aa_audit_file(profile, &perms, OP_CHANGE_HAT,
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AA_MAY_CHANGEHAT, NULL, target, NULL,
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GLOBAL_ROOT_UID, info, error);
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if (error) {
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if (error == -EACCES)
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goto kill;
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goto fail;
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}
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} /* else ignore @flags && restores when there is no saved profile */
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out:
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aa_put_profile(hat);
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kfree(name);
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aa_put_label(new);
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aa_put_label(previous);
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aa_put_label(label);
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aa_put_label(previous_label);
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put_cred(cred);
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return error;
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kill:
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info = "failed token match";
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perms.kill = AA_MAY_CHANGEHAT;
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fail:
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fn_for_each_in_ns(label, profile,
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aa_audit_file(profile, &perms, OP_CHANGE_HAT,
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AA_MAY_CHANGEHAT, NULL, NULL, target,
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GLOBAL_ROOT_UID, info, error));
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goto out;
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}
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/**
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* aa_change_profile - perform a one-way profile transition
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* @fqname: name of profile may include namespace (NOT NULL)
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