| // 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/file.h> |
| #include <linux/mount.h> |
| #include <linux/syscalls.h> |
| #include <linux/tracehook.h> |
| #include <linux/personality.h> |
| #include <linux/xattr.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 |
| * @start: state to start match in |
| * @subns: whether to do permission checks on components in a subns |
| * @request: permissions to request |
| * @perms: perms struct to set |
| * |
| * Returns: 0 on success else ERROR |
| * |
| * For the label A//&B//&C this does the perm match for A//&B//&C |
| * @perms should be preinitialized with allperms OR a previous permission |
| * check to be stacked. |
| */ |
| static int label_compound_match(struct aa_profile *profile, |
| struct aa_label *label, bool stack, |
| unsigned int state, bool subns, u32 request, |
| struct aa_perms *perms) |
| { |
| struct aa_profile *tp; |
| struct label_it i; |
| struct path_cond cond = { }; |
| |
| /* find first subcomponent that is visible */ |
| label_for_each(i, label, tp) { |
| if (!aa_ns_visible(profile->ns, tp->ns, subns)) |
| continue; |
| state = match_component(profile, tp, stack, state); |
| if (!state) |
| goto fail; |
| goto next; |
| } |
| |
| /* no component visible */ |
| *perms = allperms; |
| return 0; |
| |
| next: |
| label_for_each_cont(i, label, tp) { |
| if (!aa_ns_visible(profile->ns, tp->ns, subns)) |
| continue; |
| state = aa_dfa_match(profile->file.dfa, state, "//&"); |
| state = match_component(profile, tp, false, state); |
| if (!state) |
| goto fail; |
| } |
| *perms = aa_compute_fperms(profile->file.dfa, state, &cond); |
| aa_apply_modes_to_perms(profile, perms); |
| if ((perms->allow & request) != request) |
| return -EACCES; |
| |
| return 0; |
| |
| fail: |
| *perms = nullperms; |
| return -EACCES; |
| } |
| |
| /** |
| * label_components_match - find perms for all subcomponents of a label |
| * @profile: profile to find perms for |
| * @label: label to check access permissions for |
| * @stack: whether this is a stacking request |
| * @start: state to start match in |
| * @subns: whether to do permission checks on components in a subns |
| * @request: permissions to request |
| * @perms: an initialized perms struct to add accumulation to |
| * |
| * Returns: 0 on success else ERROR |
| * |
| * For the label A//&B//&C this does the perm match for each of A and B and C |
| * @perms should be preinitialized with allperms OR a previous permission |
| * check to be stacked. |
| */ |
| static int label_components_match(struct aa_profile *profile, |
| struct aa_label *label, bool stack, |
| unsigned int start, bool subns, u32 request, |
| struct aa_perms *perms) |
| { |
| struct aa_profile *tp; |
| struct label_it i; |
| struct aa_perms tmp; |
| struct path_cond cond = { }; |
| unsigned int state = 0; |
| |
| /* find first subcomponent to test */ |
| label_for_each(i, label, tp) { |
| if (!aa_ns_visible(profile->ns, tp->ns, subns)) |
| continue; |
| state = match_component(profile, tp, stack, start); |
| if (!state) |
| goto fail; |
| goto next; |
| } |
| |
| /* no subcomponents visible - no change in perms */ |
| return 0; |
| |
| next: |
| tmp = aa_compute_fperms(profile->file.dfa, state, &cond); |
| aa_apply_modes_to_perms(profile, &tmp); |
| aa_perms_accum(perms, &tmp); |
| label_for_each_cont(i, label, tp) { |
| if (!aa_ns_visible(profile->ns, tp->ns, subns)) |
| continue; |
| state = match_component(profile, tp, stack, start); |
| if (!state) |
| goto fail; |
| tmp = aa_compute_fperms(profile->file.dfa, state, &cond); |
| aa_apply_modes_to_perms(profile, &tmp); |
| aa_perms_accum(perms, &tmp); |
| } |
| |
| if ((perms->allow & request) != request) |
| return -EACCES; |
| |
| return 0; |
| |
| fail: |
| *perms = nullperms; |
| return -EACCES; |
| } |
| |
| /** |
| * label_match - do a multi-component label match |
| * @profile: profile to match against (NOT NULL) |
| * @label: label to match (NOT NULL) |
| * @stack: whether this is a stacking request |
| * @state: state to start in |
| * @subns: whether to match subns components |
| * @request: permission request |
| * @perms: Returns computed perms (NOT NULL) |
| * |
| * Returns: the state the match finished in, may be the none matching state |
| */ |
| static int label_match(struct aa_profile *profile, struct aa_label *label, |
| bool stack, unsigned int state, bool subns, u32 request, |
| struct aa_perms *perms) |
| { |
| int error; |
| |
| *perms = nullperms; |
| error = label_compound_match(profile, label, stack, state, subns, |
| request, perms); |
| if (!error) |
| return error; |
| |
| *perms = allperms; |
| return label_components_match(profile, label, stack, state, subns, |
| request, perms); |
| } |
| |
| /******* end TODO: dedup *****/ |
| |
| /** |
| * change_profile_perms - find permissions for change_profile |
| * @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(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 = 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; |
| } |
| /* fall through - 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; |
| struct path_cond cond = { |
| file_inode(bprm->file)->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, |
| file_inode(bprm->file)->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) |
| * @onexec: whether this transition is to take place immediately or at exec |
| * @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; |
| } |