// 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 #include #include #include #include #include #include #include #include #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_condperms(current_fsuid(), 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_condperms(current_fsuid(), 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_condperms(current_fsuid(), 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_mediates(profile, AA_CLASS_FILE)) { 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) { struct aa_perms *perms; /* * 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); perms = aa_lookup_perms(attach->xmatch, state); if (!(perms->allow & 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; struct aa_perms *perms; state = aa_dfa_leftmatch(attach->xmatch->dfa, attach->xmatch->start[AA_CLASS_XMATCH], name, &count); perms = aa_lookup_perms(attach->xmatch, state); /* any accepting state means a valid match. */ if (perms->allow & 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) * @name will always be set with the last name tried */ 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; const char *next; 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 (next = rules->file->trans.table[index]; next; next = next_name(xtype, next)) { const char *lookup = (*next == '&') ? next + 1 : next; *name = next; if (xindex & AA_X_CHILD) { /* TODO: switich to parse to get stack of child */ struct aa_profile *new = aa_find_child(profile, lookup); if (new) /* release by caller */ return &new->label; continue; } label = aa_label_parse(&profile->label, lookup, GFP_KERNEL, true, false); if (!IS_ERR_OR_NULL(label)) /* release by caller */ return label; } return NULL; } /** * 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_label *stack = NULL; struct aa_ns *ns = profile->ns; u32 xtype = xindex & AA_X_TYPE_MASK; 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 */ /* released by caller * if null for both stack and direct want to try fallback*/ new = x_table_lookup(profile, xindex, lookupname); if (!new || **lookupname != '&') break; stack = new; new = NULL; 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; } /* fallback transition check */ 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_merge(base, stack, GFP_KERNEL); /* null on error */ aa_put_label(base); } aa_put_label(stack); /* 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_mediates(profile, AA_CLASS_FILE) || (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) { AA_DEBUG(DEBUG_DOMAIN, "name lookup ix on error"); error = 0; new = aa_get_newest_label(&profile->label); } name = bprm->filename; goto audit; } if (!profile_mediates(profile, AA_CLASS_FILE)) { new = find_attach(bprm, profile->ns, &profile->ns->base.profiles, name, &info); if (new) { AA_DEBUG(DEBUG_DOMAIN, "unconfined attached to new label"); return new; } AA_DEBUG(DEBUG_DOMAIN, "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, true); 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_mediates(profile, AA_CLASS_FILE)) { /* 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_mediates(profile, AA_CLASS_FILE) || (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) { AA_DEBUG(DEBUG_DOMAIN, "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, false); } /* 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, false)); 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) && label_mediates(label, AA_CLASS_FILE) && !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) && label_mediates(label, AA_CLASS_FILE) && !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, false)); 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, false); 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, false); } } 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); if (!label_mediates(label, AA_CLASS_FILE)) { info = "unconfined can not change_hat"; error = -EPERM; goto fail; } /* * 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 mediation must be done before the subset test */ if (task_no_new_privs(current) && !ctx->nnp) ctx->nnp = aa_get_label(label); /* return -EPERM when unconfined doesn't have children to avoid * changing the traditional error code for unconfined. */ if (unconfined(label)) { struct label_it i; bool empty = true; rcu_read_lock(); label_for_each_in_ns(i, labels_ns(label), label, profile) { empty &= list_empty(&profile->base.profiles); } rcu_read_unlock(); if (empty) { 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. * label_mediates(label, AA_CLASS_FILE) == true here */ if (task_no_new_privs(current) && !aa_label_is_unconfined_subset(new, ctx->nnp)) { /* not an apparmor denial per se, so don't log it */ AA_DEBUG(DEBUG_DOMAIN, "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. * label_mediates(label, AA_CLASS_FILE) == true here */ if (task_no_new_privs(current) && !aa_label_is_unconfined_subset(previous, ctx->nnp)) { /* not an apparmor denial per se, so don't log it */ AA_DEBUG(DEBUG_DOMAIN, "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, false)); 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, false); 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) && label_mediates(label, AA_CLASS_FILE) && !ctx->nnp) ctx->nnp = aa_get_label(label); if (!fqname || !*fqname) { aa_put_label(label); AA_DEBUG(DEBUG_DOMAIN, "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 && !label_mediates(label, AA_CLASS_FILE) && 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, false)); 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) && label_mediates(label, AA_CLASS_FILE) && !aa_label_is_unconfined_subset(new, ctx->nnp)) { /* not an apparmor denial per se, so don't log it */ AA_DEBUG(DEBUG_DOMAIN, "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, false)); out: aa_put_label(new); aa_put_label(target); aa_put_label(label); put_cred(subj_cred); return error; }