From 89dbf1962aa636341658c26034c0e113cc9d1776 Mon Sep 17 00:00:00 2001 From: John Johansen Date: Fri, 9 Jun 2017 17:01:43 -0700 Subject: apparmor: move change_hat mediation to using labels Signed-off-by: John Johansen --- security/apparmor/domain.c | 303 ++++++++++++++++++++++++++++++--------------- 1 file changed, 201 insertions(+), 102 deletions(-) (limited to 'security') diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c index cb8509373ea3..a1d73033b42e 100644 --- a/security/apparmor/domain.c +++ b/security/apparmor/domain.c @@ -884,19 +884,153 @@ int apparmor_bprm_secureexec(struct linux_binprm *bprm) * Functions for self directed profile change */ -/** - * new_compound_name - create an hname with @n2 appended to @n1 - * @n1: base of hname (NOT NULL) - * @n2: name to append (NOT NULL) + +/* helper fn for change_hat * - * Returns: new name or NULL on error + * Returns: label for hat transition OR ERR_PTR. Does NOT return NULL */ -static char *new_compound_name(const char *n1, const char *n2) +static struct aa_label *build_change_hat(struct aa_profile *profile, + const char *name, bool sibling) { - char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL); - if (name) - sprintf(name, "%s//%s", n1, n2); - return name; + 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_null_profile(profile, true, name, + GFP_KERNEL); + if (!hat) { + info = "failed null profile create"; + error = -ENOMEM; + } + } + } + aa_put_profile(root); + +audit: + aa_audit_file(profile, &nullperms, OP_CHANGE_HAT, AA_MAY_CHANGEHAT, + name, hat ? hat->base.hname : NULL, + hat ? &hat->label : NULL, GLOBAL_ROOT_UID, NULL, + 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(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(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(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; } /** @@ -906,23 +1040,24 @@ static char *new_compound_name(const char *n1, const char *n2) * @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. * - * Returns %0 on success, error otherwise. + * 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 *cred; struct aa_task_ctx *ctx; - struct aa_label *label, *previous_label; - struct aa_profile *profile, *hat = NULL; - char *name = NULL; - int i; + struct aa_label *label, *previous, *new = NULL, *target = NULL; + struct aa_profile *profile; struct aa_perms perms = {}; - const char *target = NULL, *info = NULL; + const char *info = NULL; int error = 0; /* @@ -930,118 +1065,82 @@ int aa_change_hat(const char *hats[], int count, u64 token, int flags) * There is no exception for unconfined as change_hat is not * available. */ - if (task_no_new_privs(current)) + if (task_no_new_privs(current)) { + /* not an apparmor denial per se, so don't log it */ + AA_DEBUG("no_new_privs - change_hat denied"); return -EPERM; + } /* released below */ cred = get_current_cred(); ctx = cred_ctx(cred); label = aa_get_newest_cred_label(cred); - previous_label = aa_get_newest_label(ctx->previous); - profile = labels_profile(label); + previous = aa_get_newest_label(ctx->previous); if (unconfined(label)) { - info = "unconfined"; + info = "unconfined can not change_hat"; error = -EPERM; - goto audit; + goto fail; } if (count) { - /* attempting to change into a new hat or switch to a sibling */ - struct aa_profile *root; - if (PROFILE_IS_HAT(profile)) - root = aa_get_profile_rcu(&profile->parent); - else - root = aa_get_profile(profile); - - /* find first matching hat */ - for (i = 0; i < count && !hat; i++) - /* released below */ - hat = aa_find_child(root, hats[i]); - if (!hat) { - if (!COMPLAIN_MODE(root) || (flags & AA_CHANGE_TEST)) { - if (list_empty(&root->base.profiles)) - error = -ECHILD; - else - error = -ENOENT; - aa_put_profile(root); - goto out; - } - - /* - * In complain mode and failed to match any hats. - * Audit the failure is based off of the first hat - * supplied. This is done due how userspace - * interacts with change_hat. - * - * TODO: Add logging of all failed hats - */ - - /* freed below */ - name = new_compound_name(root->base.hname, hats[0]); - aa_put_profile(root); - target = name; - /* released below */ - hat = aa_new_null_profile(profile, true, hats[0], - GFP_KERNEL); - if (!hat) { - info = "failed null profile create"; - error = -ENOMEM; - goto audit; - } - } else { - aa_put_profile(root); - target = hat->base.hname; - if (!PROFILE_IS_HAT(hat)) { - info = "target not hat"; - error = -EPERM; - goto audit; - } + new = change_hat(label, hats, count, flags); + AA_BUG(!new); + if (IS_ERR(new)) { + error = PTR_ERR(new); + new = NULL; + /* already audited */ + goto out; } - error = may_change_ptraced_domain(&hat->label, &info); - if (error) { - info = "ptraced"; - error = -EPERM; - goto audit; - } + error = may_change_ptraced_domain(new, &info); + if (error) + goto fail; - if (!(flags & AA_CHANGE_TEST)) { - error = aa_set_current_hat(&hat->label, token); - if (error == -EACCES) - /* kill task in case of brute force attacks */ - perms.kill = AA_MAY_CHANGEHAT; - else if (name && !error) - /* reset error for learning of new hats */ - error = -ENOENT; - } - } else if (previous_label) { - /* Return to saved profile. Kill task if restore fails + 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)) { + /* Return to saved label. Kill task if restore fails * to avoid brute force attacks */ - target = previous_label->hname; + target = previous; error = aa_restore_previous_label(token); - perms.kill = AA_MAY_CHANGEHAT; - } else - /* ignore restores when there is no saved profile */ - goto out; - -audit: - if (!(flags & AA_CHANGE_TEST)) - error = aa_audit_file(profile, &perms, OP_CHANGE_HAT, - AA_MAY_CHANGEHAT, NULL, target, NULL, - GLOBAL_ROOT_UID, info, error); + if (error) { + if (error == -EACCES) + goto kill; + goto fail; + } + } /* else ignore @flags && restores when there is no saved profile */ out: - aa_put_profile(hat); - kfree(name); + aa_put_label(new); + aa_put_label(previous); aa_put_label(label); - aa_put_label(previous_label); put_cred(cred); return error; + +kill: + info = "failed token match"; + perms.kill = AA_MAY_CHANGEHAT; + +fail: + fn_for_each_in_ns(label, profile, + aa_audit_file(profile, &perms, OP_CHANGE_HAT, + AA_MAY_CHANGEHAT, NULL, NULL, target, + GLOBAL_ROOT_UID, info, error)); + + goto out; } + + /** * aa_change_profile - perform a one-way profile transition * @fqname: name of profile may include namespace (NOT NULL) -- cgit v1.2.3