/* * AppArmor security module * * This file contains AppArmor policy attachment and domain transitions * * Copyright (C) 2002-2008 Novell/SUSE * Copyright 2009-2010 Canonical Ltd. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation, version 2 of the * License. */ #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++) kzfree(domain->table[i]); kzfree(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; /* transition from exec match to xattr set */ state = aa_dfa_null_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 value, not just presence */ 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_null_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; } /** * __attach_match_ - find an attachment match * @bprm - binprm structure of transitioning task * @name - to match against (NOT NULL) * @head - profile list to walk (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: profile or NULL if no match found */ static struct aa_profile *__attach_match(const struct linux_binprm *bprm, const char *name, struct list_head *head, 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); 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; if (count < candidate_len) continue; ret = aa_xattrs_match(bprm, profile, state); /* 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 */ return profile; } if (conflict) { *info = "conflicting profile attachments"; return NULL; } return candidate; } /** * find_attach - do attachment search for unconfined processes * @bprm - binprm structure of transitioning task * @ns: the current namespace (NOT NULL) * @list: list to search (NOT NULL) * @name: the executable name to match against (NOT NULL) * @info: info message if there was an error * * 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 *list, const char *name, const char **info) { struct aa_profile *profile; rcu_read_lock(); profile = aa_get_profile(__attach_match(bprm, name, list, info)); rcu_read_unlock(); return profile ? &profile->label : NULL; } 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_ATOMIC, 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_ATOMIC, 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; struct aa_profile *component; struct label_it i; 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 { /* verify that each component's xattr requirements are * met, and fail execution otherwise */ label_for_each(i, new, component) { if (aa_xattrs_match(bprm, component, state) < 0) { error = -EACCES; info = "required xattrs not present"; perms.allow &= ~MAY_EXEC; aa_put_label(new); new = NULL; goto audit; } } } } else if (COMPLAIN_MODE(profile)) { /* no exec permission - learning mode */ struct aa_profile *new_profile = NULL; char *n = kstrdup(name, GFP_ATOMIC); if (n) { /* name is ptr into buffer */ long pos = name - buffer; /* break per cpu buffer hold */ put_buffers(buffer); new_profile = aa_new_null_profile(profile, false, n, GFP_KERNEL); get_buffers(buffer); name = buffer + pos; strcpy((char *)name, n); kfree(n); } 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_ATOMIC); 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_ATOMIC); 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_ATOMIC, 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_ATOMIC, aa_label_merge(&profile->label, onexec, GFP_ATOMIC), 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_set_creds - set 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_set_creds(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 }; if (bprm->called_set_creds) return 0; 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 */ get_buffers(buffer); /* 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_ATOMIC, 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_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_ATOMIC); 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_ATOMIC); dbg_printk("\n"); } bprm->per_clear |= PER_CLEAR_ON_SETID; } aa_put_label(cred_label(bprm->cred)); /* transfer reference, released when cred is freed */ cred_label(bprm->cred) = new; done: aa_put_label(label); put_buffers(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_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_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_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; } label = aa_get_current_label(); 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_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"; 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; }