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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * AppArmor security module
- *
- * This file contains AppArmor policy attachment and domain transitions
- *
- * Copyright (C) 2002-2008 Novell/SUSE
- * Copyright 2009-2010 Canonical Ltd.
- */
- #include <linux/errno.h>
- #include <linux/fdtable.h>
- #include <linux/fs.h>
- #include <linux/file.h>
- #include <linux/mount.h>
- #include <linux/syscalls.h>
- #include <linux/personality.h>
- #include <linux/xattr.h>
- #include <linux/user_namespace.h>
- #include "include/audit.h"
- #include "include/apparmorfs.h"
- #include "include/cred.h"
- #include "include/domain.h"
- #include "include/file.h"
- #include "include/ipc.h"
- #include "include/match.h"
- #include "include/path.h"
- #include "include/policy.h"
- #include "include/policy_ns.h"
- /**
- * aa_free_domain_entries - free entries in a domain table
- * @domain: the domain table to free (MAYBE NULL)
- */
- void aa_free_domain_entries(struct aa_domain *domain)
- {
- int i;
- if (domain) {
- if (!domain->table)
- return;
- for (i = 0; i < domain->size; i++)
- kfree_sensitive(domain->table[i]);
- kfree_sensitive(domain->table);
- domain->table = NULL;
- }
- }
- /**
- * may_change_ptraced_domain - check if can change profile on ptraced task
- * @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(struct aa_label *to_label,
- const char **info)
- {
- struct task_struct *tracer;
- struct aa_label *tracerl = NULL;
- int error = 0;
- rcu_read_lock();
- tracer = ptrace_parent(current);
- if (tracer)
- /* released below */
- tracerl = aa_get_task_label(tracer);
- /* not ptraced */
- if (!tracer || unconfined(tracerl))
- goto out;
- error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
- out:
- rcu_read_unlock();
- aa_put_label(tracerl);
- 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 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
- * @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,
- 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
- * @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
- *
- *
- * 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, 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);
- }
- /**
- * 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, unsigned int state)
- {
- int i;
- ssize_t size;
- struct dentry *d;
- char *value = NULL;
- int value_size = 0, ret = profile->xattr_count;
- if (!bprm || !profile->xattr_count)
- return 0;
- might_sleep();
- /* transition from exec match to xattr set */
- state = aa_dfa_outofband_transition(profile->xmatch, state);
- d = bprm->file->f_path.dentry;
- for (i = 0; i < profile->xattr_count; i++) {
- size = vfs_getxattr_alloc(&init_user_ns, d, profile->xattrs[i],
- &value, value_size, GFP_KERNEL);
- if (size >= 0) {
- u32 perm;
- /*
- * Check the xattr presence before value. This ensure
- * that not present xattr can be distinguished from a 0
- * length value or rule that matches any value
- */
- state = aa_dfa_null_transition(profile->xmatch, state);
- /* Check xattr value */
- state = aa_dfa_match_len(profile->xmatch, state, value,
- size);
- perm = dfa_user_allow(profile->xmatch, state);
- if (!(perm & MAY_EXEC)) {
- ret = -EINVAL;
- goto out;
- }
- }
- /* transition to next element */
- state = aa_dfa_outofband_transition(profile->xmatch, 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) {
- 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 (profile->xmatch) {
- unsigned int state, count;
- u32 perm;
- state = aa_dfa_leftmatch(profile->xmatch, DFA_START,
- name, &count);
- perm = dfa_user_allow(profile->xmatch, state);
- /* any accepting state means a valid match. */
- if (perm & MAY_EXEC) {
- int ret = 0;
- if (count < candidate_len)
- continue;
- if (bprm && profile->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, profile->xmatch_len);
- candidate_xattrs = ret;
- conflict = false;
- }
- } else if (!strcmp(profile->base.name, name)) {
- /*
- * old exact non-re match, without conditionals such
- * as xattrs. no more searching required
- */
- candidate = profile;
- goto out;
- }
- }
- if (!candidate || conflict) {
- if (conflict)
- *info = "conflicting profile attachments";
- rcu_read_unlock();
- return NULL;
- }
- out:
- candidate = aa_get_newest_profile(candidate);
- rcu_read_unlock();
- return &candidate->label;
- }
- static const char *next_name(int xtype, const char *name)
- {
- return NULL;
- }
- /**
- * x_table_lookup - lookup an x transition name via transition table
- * @profile: current profile (NOT NULL)
- * @xindex: index into x transition table
- * @name: returns: name tested to find label (NOT NULL)
- *
- * Returns: refcounted label, or NULL on failure (MAYBE NULL)
- */
- struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
- const char **name)
- {
- struct aa_label *label = NULL;
- u32 xtype = xindex & AA_X_TYPE_MASK;
- int index = xindex & AA_X_INDEX_MASK;
- AA_BUG(!name);
- /* index is guaranteed to be in range, validated at load time */
- /* TODO: move lookup parsing to unpack time so this is a straight
- * index into the resultant label
- */
- for (*name = profile->file.trans.table[index]; !label && *name;
- *name = next_name(xtype, *name)) {
- if (xindex & AA_X_CHILD) {
- struct aa_profile *new_profile;
- /* release by caller */
- new_profile = aa_find_child(profile, *name);
- if (new_profile)
- label = &new_profile->label;
- continue;
- }
- label = aa_label_parse(&profile->label, *name, GFP_KERNEL,
- true, false);
- if (IS_ERR(label))
- label = NULL;
- }
- /* released by caller */
- return label;
- }
- /**
- * x_to_label - get target label for a given xindex
- * @profile: current profile (NOT NULL)
- * @bprm: binprm structure of transitioning task
- * @name: name to lookup (NOT NULL)
- * @xindex: index into x transition table
- * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
- *
- * 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_label *new = NULL;
- struct aa_ns *ns = profile->ns;
- u32 xtype = xindex & AA_X_TYPE_MASK;
- const char *stack = NULL;
- switch (xtype) {
- case AA_X_NONE:
- /* fail exec unless ix || ux fallback - handled by caller */
- *lookupname = NULL;
- break;
- case AA_X_TABLE:
- /* TODO: fix when perm mapping done at unload */
- stack = profile->file.trans.table[xindex & AA_X_INDEX_MASK];
- if (*stack != '&') {
- /* released by caller */
- new = x_table_lookup(profile, xindex, lookupname);
- stack = NULL;
- break;
- }
- fallthrough; /* to X_NAME */
- case AA_X_NAME:
- if (xindex & AA_X_CHILD)
- /* released by caller */
- new = find_attach(bprm, ns, &profile->base.profiles,
- name, info);
- else
- /* released by caller */
- new = find_attach(bprm, ns, &ns->base.profiles,
- name, info);
- *lookupname = name;
- break;
- }
- if (!new) {
- if (xindex & AA_X_INHERIT) {
- /* (p|c|n)ix - don't change profile but do
- * use the newest version
- */
- *info = "ix fallback";
- /* no profile && no error */
- new = aa_get_newest_label(&profile->label);
- } else if (xindex & AA_X_UNCONFINED) {
- new = aa_get_newest_label(ns_unconfined(profile->ns));
- *info = "ux fallback";
- }
- }
- if (new && stack) {
- /* base the stack on post domain transition */
- struct aa_label *base = new;
- new = aa_label_parse(base, stack, GFP_KERNEL, true, false);
- if (IS_ERR(new))
- new = NULL;
- aa_put_label(base);
- }
- /* released by caller */
- return new;
- }
- static struct aa_label *profile_transition(struct aa_profile *profile,
- const struct linux_binprm *bprm,
- char *buffer, struct path_cond *cond,
- bool *secure_exec)
- {
- struct aa_label *new = NULL;
- const char *info = NULL, *name = NULL, *target = NULL;
- unsigned int state = profile->file.start;
- struct aa_perms perms = {};
- bool nonewprivs = false;
- int error = 0;
- AA_BUG(!profile);
- AA_BUG(!bprm);
- AA_BUG(!buffer);
- error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
- &name, &info, profile->disconnected);
- if (error) {
- if (profile_unconfined(profile) ||
- (profile->label.flags & FLAG_IX_ON_NAME_ERROR)) {
- AA_DEBUG("name lookup ix on error");
- error = 0;
- new = aa_get_newest_label(&profile->label);
- }
- name = bprm->filename;
- goto audit;
- }
- if (profile_unconfined(profile)) {
- new = find_attach(bprm, profile->ns,
- &profile->ns->base.profiles, name, &info);
- if (new) {
- AA_DEBUG("unconfined attached to new label");
- return new;
- }
- AA_DEBUG("unconfined exec no attachment");
- return aa_get_newest_label(&profile->label);
- }
- /* find exec permissions for name */
- state = aa_str_perms(profile->file.dfa, 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_null_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(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;
- }
- /* 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;
- }
- 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(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_KERNEL,
- aa_get_newest_label(onexec),
- profile_transition(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(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(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_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;
- struct aa_profile *profile;
- char *buffer = NULL;
- const char *info = NULL;
- int error = 0;
- bool unsafe = false;
- kuid_t i_uid = i_uid_into_mnt(file_mnt_user_ns(bprm->file),
- file_inode(bprm->file));
- struct path_cond cond = {
- i_uid,
- file_inode(bprm->file)->i_mode
- };
- ctx = task_ctx(current);
- AA_BUG(!cred_label(bprm->cred));
- AA_BUG(!ctx);
- label = aa_get_newest_label(cred_label(bprm->cred));
- /*
- * Detect no new privs being set, and store the label it
- * occurred under. Ideally this would happen when nnp
- * is set but there isn't a good way to do that yet.
- *
- * Testing for unconfined must be done before the subset test
- */
- if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
- !ctx->nnp)
- ctx->nnp = aa_get_label(label);
- /* buffer freed below, name is pointer into buffer */
- buffer = aa_get_buffer(false);
- if (!buffer) {
- error = -ENOMEM;
- goto done;
- }
- /* Test for onexec first as onexec override other x transitions. */
- if (ctx->onexec)
- new = handle_onexec(label, ctx->onexec, ctx->token,
- bprm, buffer, &cond, &unsafe);
- else
- new = fn_label_build(label, profile, GFP_KERNEL,
- 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;
- }
- /* Policy has specified a domain transitions. If no_new_privs and
- * confined ensure the transition is to confinement that is subset
- * of the confinement when the task entered no new privs.
- *
- * NOTE: Domain transitions from unconfined and to stacked
- * subsets are allowed even when no_new_privs is set because this
- * aways results in a further reduction of permissions.
- */
- if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
- !unconfined(label) &&
- !aa_label_is_unconfined_subset(new, ctx->nnp)) {
- error = -EPERM;
- info = "no new privs";
- goto audit;
- }
- if (bprm->unsafe & LSM_UNSAFE_SHARE) {
- /* FIXME: currently don't mediate shared state */
- ;
- }
- if (bprm->unsafe & (LSM_UNSAFE_PTRACE)) {
- /* TODO: test needs to be profile of label to new */
- error = may_change_ptraced_domain(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(profile, &nullperms, OP_EXEC, MAY_EXEC,
- bprm->filename, NULL, new,
- i_uid, info, error));
- aa_put_label(new);
- goto done;
- }
- /*
- * Functions for self directed profile change
- */
- /* helper fn for change_hat
- *
- * Returns: label for hat transition OR ERR_PTR. Does NOT return NULL
- */
- static struct aa_label *build_change_hat(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_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, info,
- error);
- if (!hat || (error && error != -ENOENT))
- return ERR_PTR(error);
- /* if hat && error - complain mode, already audited and we adjust for
- * complain mode allow by returning hat->label
- */
- return &hat->label;
- }
- /* helper fn for changing into a hat
- *
- * Returns: label for hat transition or ERR_PTR. Does not return NULL
- */
- static struct aa_label *change_hat(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;
- }
- /**
- * 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 *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 */
- cred = get_current_cred();
- label = aa_get_newest_cred_label(cred);
- previous = aa_get_newest_label(ctx->previous);
- /*
- * Detect no new privs being set, and store the label it
- * occurred under. Ideally this would happen when nnp
- * is set but there isn't a good way to do that yet.
- *
- * Testing for unconfined must be done before the subset test
- */
- if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
- ctx->nnp = aa_get_label(label);
- if (unconfined(label)) {
- info = "unconfined can not change_hat";
- error = -EPERM;
- goto fail;
- }
- if (count) {
- new = change_hat(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(new, &info);
- if (error)
- goto fail;
- /*
- * no new privs prevents domain transitions that would
- * reduce restrictions.
- */
- if (task_no_new_privs(current) && !unconfined(label) &&
- !aa_label_is_unconfined_subset(new, ctx->nnp)) {
- /* not an apparmor denial per se, so don't log it */
- AA_DEBUG("no_new_privs - change_hat denied");
- error = -EPERM;
- goto out;
- }
- if (flags & AA_CHANGE_TEST)
- goto out;
- target = new;
- error = aa_set_current_hat(new, token);
- if (error == -EACCES)
- /* kill task in case of brute force attacks */
- goto kill;
- } else if (previous && !(flags & AA_CHANGE_TEST)) {
- /*
- * no new privs prevents domain transitions that would
- * reduce restrictions.
- */
- if (task_no_new_privs(current) && !unconfined(label) &&
- !aa_label_is_unconfined_subset(previous, ctx->nnp)) {
- /* not an apparmor denial per se, so don't log it */
- AA_DEBUG("no_new_privs - change_hat denied");
- error = -EPERM;
- goto out;
- }
- /* Return to saved label. Kill task if restore fails
- * to avoid brute force attacks
- */
- target = previous;
- error = aa_restore_previous_label(token);
- if (error) {
- if (error == -EACCES)
- goto kill;
- goto fail;
- }
- } /* else ignore @flags && restores when there is no saved profile */
- out:
- aa_put_label(new);
- aa_put_label(previous);
- aa_put_label(label);
- put_cred(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;
- }
- static int change_profile_perms_wrapper(const char *op, const char *name,
- struct aa_profile *profile,
- struct aa_label *target, bool stack,
- u32 request, struct aa_perms *perms)
- {
- const char *info = NULL;
- int error = 0;
- if (!error)
- error = change_profile_perms(profile, target, stack, request,
- profile->file.start, perms);
- if (error)
- error = aa_audit_file(profile, perms, op, request, name,
- NULL, target, GLOBAL_ROOT_UID, info,
- error);
- return error;
- }
- /**
- * 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);
- int error = 0;
- char *op;
- u32 request;
- label = aa_get_current_label();
- /*
- * Detect no new privs being set, and store the label it
- * occurred under. Ideally this would happen when nnp
- * is set but there isn't a good way to do that yet.
- *
- * Testing for unconfined must be done before the subset test
- */
- if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
- ctx->nnp = aa_get_label(label);
- if (!fqname || !*fqname) {
- aa_put_label(label);
- AA_DEBUG("no profile name");
- return -EINVAL;
- }
- if (flags & AA_CHANGE_ONEXEC) {
- request = AA_MAY_ONEXEC;
- if (stack)
- op = OP_STACK_ONEXEC;
- else
- op = OP_CHANGE_ONEXEC;
- } else {
- request = AA_MAY_CHANGE_PROFILE;
- if (stack)
- op = OP_STACK;
- else
- op = OP_CHANGE_PROFILE;
- }
- 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_null_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,
- 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(target, &info);
- if (error && !fn_for_each_in_ns(label, profile,
- COMPLAIN_MODE(profile)))
- goto audit;
- /* TODO: add permission check to allow this
- * if ((flags & AA_CHANGE_ONEXEC) && !current_is_single_threaded()) {
- * info = "not a single threaded task";
- * error = -EACCES;
- * goto audit;
- * }
- */
- if (flags & AA_CHANGE_TEST)
- goto out;
- /* stacking is always a subset, so only check the nonstack case */
- if (!stack) {
- new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
- aa_get_label(target),
- aa_get_label(&profile->label));
- /*
- * no new privs prevents domain transitions that would
- * reduce restrictions.
- */
- if (task_no_new_privs(current) && !unconfined(label) &&
- !aa_label_is_unconfined_subset(new, ctx->nnp)) {
- /* not an apparmor denial per se, so don't log it */
- AA_DEBUG("no_new_privs - change_hat denied");
- error = -EPERM;
- goto out;
- }
- }
- if (!(flags & AA_CHANGE_ONEXEC)) {
- /* only transition profiles in the current ns */
- if (stack)
- new = aa_label_merge(label, target, GFP_KERNEL);
- if (IS_ERR_OR_NULL(new)) {
- info = "failed to build target label";
- if (!new)
- error = -ENOMEM;
- else
- error = PTR_ERR(new);
- new = NULL;
- perms.allow = 0;
- goto audit;
- }
- error = aa_replace_current_label(new);
- } else {
- if (new) {
- aa_put_label(new);
- new = NULL;
- }
- /* full transition will be built in exec path */
- error = aa_set_current_onexec(target, stack);
- }
- audit:
- error = fn_for_each_in_ns(label, profile,
- aa_audit_file(profile, &perms, op, request, auditname,
- NULL, new ? new : target,
- GLOBAL_ROOT_UID, info, error));
- out:
- aa_put_label(new);
- aa_put_label(target);
- aa_put_label(label);
- return error;
- }
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