diff options
Diffstat (limited to 'security/apparmor/domain.c')
| -rw-r--r-- | security/apparmor/domain.c | 1495 |
1 files changed, 1495 insertions, 0 deletions
diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c new file mode 100644 index 000000000..543105cf7 --- /dev/null +++ b/security/apparmor/domain.c @@ -0,0 +1,1495 @@ +// 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" + +/** + * may_change_ptraced_domain - check if can change profile on ptraced task + * @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_fperms(&(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_fperms(&(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_fperms(&(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 + * + * + * 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_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, 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) { + u32 index, 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(attach->xmatch.dfa, + state); + /* Check xattr value */ + state = aa_dfa_match_len(attach->xmatch.dfa, state, + value, size); + index = ACCEPT_TABLE(attach->xmatch.dfa)[state]; + perm = attach->xmatch.perms[index].allow; + if (!(perm & 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; + u32 index, perm; + + state = aa_dfa_leftmatch(attach->xmatch.dfa, + attach->xmatch.start[AA_CLASS_XMATCH], + name, &count); + index = ACCEPT_TABLE(attach->xmatch.dfa)[state]; + perm = attach->xmatch.perms[index].allow; + /* any accepting state means a valid match. */ + if (perm & 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) + */ +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; + + 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 = rules->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_ruleset *rules = list_first_entry(&profile->rules, + typeof(*rules), list); + 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 = rules->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(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_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(&(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); + 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_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(&(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); +} + +/* 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)); + 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) && !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(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) && + !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(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)); + 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); + 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); + } + } + 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); + + /* + * 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(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. + */ + 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(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)); + + 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); + + 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); + 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) && !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_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) && !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(subj_cred, + 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); + put_cred(subj_cred); + + return error; +} |