diff options
Diffstat (limited to 'security/apparmor/domain.c')
| -rw-r--r-- | security/apparmor/domain.c | 823 |
1 files changed, 823 insertions, 0 deletions
diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c new file mode 100644 index 000000000000..08bbe6397a7f --- /dev/null +++ b/security/apparmor/domain.c @@ -0,0 +1,823 @@ +/* + * 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 "include/audit.h" +#include "include/apparmorfs.h" +#include "include/context.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" + +/** + * 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 + * @task: task we want to change profile of (NOT NULL) + * @to_profile: profile to change to (NOT NULL) + * + * Check if the task 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 task_struct *task, + struct aa_profile *to_profile) +{ + struct task_struct *tracer; + struct cred *cred = NULL; + struct aa_profile *tracerp = NULL; + int error = 0; + + rcu_read_lock(); + tracer = tracehook_tracer_task(task); + if (tracer) { + /* released below */ + cred = get_task_cred(tracer); + tracerp = aa_cred_profile(cred); + } + rcu_read_unlock(); + + /* not ptraced */ + if (!tracer || unconfined(tracerp)) + goto out; + + error = aa_may_ptrace(tracer, tracerp, to_profile, PTRACE_MODE_ATTACH); + +out: + if (cred) + put_cred(cred); + + return error; +} + +/** + * change_profile_perms - find permissions for change_profile + * @profile: the current profile (NOT NULL) + * @ns: the namespace being switched to (NOT NULL) + * @name: the name of the profile to change to (NOT NULL) + * @request: requested perms + * @start: state to start matching in + * + * Returns: permission set + */ +static struct file_perms change_profile_perms(struct aa_profile *profile, + struct aa_namespace *ns, + const char *name, u32 request, + unsigned int start) +{ + struct file_perms perms; + struct path_cond cond = { }; + unsigned int state; + + if (unconfined(profile)) { + perms.allow = AA_MAY_CHANGE_PROFILE | AA_MAY_ONEXEC; + perms.audit = perms.quiet = perms.kill = 0; + return perms; + } else if (!profile->file.dfa) { + return nullperms; + } else if ((ns == profile->ns)) { + /* try matching against rules with out namespace prepended */ + aa_str_perms(profile->file.dfa, start, name, &cond, &perms); + if (COMBINED_PERM_MASK(perms) & request) + return perms; + } + + /* try matching with namespace name and then profile */ + state = aa_dfa_match(profile->file.dfa, start, ns->base.name); + state = aa_dfa_match_len(profile->file.dfa, state, ":", 1); + aa_str_perms(profile->file.dfa, state, name, &cond, &perms); + + return perms; +} + +/** + * __attach_match_ - find an attachment match + * @name - to match against (NOT NULL) + * @head - profile list to walk (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 char *name, + struct list_head *head) +{ + int len = 0; + struct aa_profile *profile, *candidate = NULL; + + list_for_each_entry(profile, head, base.list) { + if (profile->flags & PFLAG_NULL) + continue; + if (profile->xmatch && profile->xmatch_len > len) { + unsigned int state = aa_dfa_match(profile->xmatch, + DFA_START, name); + u32 perm = dfa_user_allow(profile->xmatch, state); + /* any accepting state means a valid match. */ + if (perm & MAY_EXEC) { + candidate = profile; + len = profile->xmatch_len; + } + } else if (!strcmp(profile->base.name, name)) + /* exact non-re match, no more searching required */ + return profile; + } + + return candidate; +} + +/** + * find_attach - do attachment search for unconfined processes + * @ns: the current namespace (NOT NULL) + * @list: list to search (NOT NULL) + * @name: the executable name to match against (NOT NULL) + * + * Returns: profile or NULL if no match found + */ +static struct aa_profile *find_attach(struct aa_namespace *ns, + struct list_head *list, const char *name) +{ + struct aa_profile *profile; + + read_lock(&ns->lock); + profile = aa_get_profile(__attach_match(name, list)); + read_unlock(&ns->lock); + + return profile; +} + +/** + * separate_fqname - separate the namespace and profile names + * @fqname: the fqname name to split (NOT NULL) + * @ns_name: the namespace name if it exists (NOT NULL) + * + * This is the xtable equivalent routine of aa_split_fqname. It finds the + * split in an xtable fqname which contains an embedded \0 instead of a : + * if a namespace is specified. This is done so the xtable is constant and + * isn't re-split on every lookup. + * + * Either the profile or namespace name may be optional but if the namespace + * is specified the profile name termination must be present. This results + * in the following possible encodings: + * profile_name\0 + * :ns_name\0profile_name\0 + * :ns_name\0\0 + * + * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table + * + * Returns: profile name if it is specified else NULL + */ +static const char *separate_fqname(const char *fqname, const char **ns_name) +{ + const char *name; + + if (fqname[0] == ':') { + /* In this case there is guaranteed to be two \0 terminators + * in the string. They are verified at load time by + * by unpack_trans_table + */ + *ns_name = fqname + 1; /* skip : */ + name = *ns_name + strlen(*ns_name) + 1; + if (!*name) + name = NULL; + } else { + *ns_name = NULL; + name = fqname; + } + + return name; +} + +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 + * + * Returns: refcounted profile, or NULL on failure (MAYBE NULL) + */ +static struct aa_profile *x_table_lookup(struct aa_profile *profile, u32 xindex) +{ + struct aa_profile *new_profile = NULL; + struct aa_namespace *ns = profile->ns; + u32 xtype = xindex & AA_X_TYPE_MASK; + int index = xindex & AA_X_INDEX_MASK; + const char *name; + + /* index is guaranteed to be in range, validated at load time */ + for (name = profile->file.trans.table[index]; !new_profile && name; + name = next_name(xtype, name)) { + struct aa_namespace *new_ns; + const char *xname = NULL; + + new_ns = NULL; + if (xindex & AA_X_CHILD) { + /* release by caller */ + new_profile = aa_find_child(profile, name); + continue; + } else if (*name == ':') { + /* switching namespace */ + const char *ns_name; + xname = name = separate_fqname(name, &ns_name); + if (!xname) + /* no name so use profile name */ + xname = profile->base.hname; + if (*ns_name == '@') { + /* TODO: variable support */ + ; + } + /* released below */ + new_ns = aa_find_namespace(ns, ns_name); + if (!new_ns) + continue; + } else if (*name == '@') { + /* TODO: variable support */ + continue; + } else { + /* basic namespace lookup */ + xname = name; + } + + /* released by caller */ + new_profile = aa_lookup_profile(new_ns ? new_ns : ns, xname); + aa_put_namespace(new_ns); + } + + /* released by caller */ + return new_profile; +} + +/** + * x_to_profile - get target profile for a given xindex + * @profile: current profile (NOT NULL) + * @name: name to lookup (NOT NULL) + * @xindex: index into x transition table + * + * find profile for a transition index + * + * Returns: refcounted profile or NULL if not found available + */ +static struct aa_profile *x_to_profile(struct aa_profile *profile, + const char *name, u32 xindex) +{ + struct aa_profile *new_profile = NULL; + struct aa_namespace *ns = profile->ns; + u32 xtype = xindex & AA_X_TYPE_MASK; + + switch (xtype) { + case AA_X_NONE: + /* fail exec unless ix || ux fallback - handled by caller */ + return NULL; + case AA_X_NAME: + if (xindex & AA_X_CHILD) + /* released by caller */ + new_profile = find_attach(ns, &profile->base.profiles, + name); + else + /* released by caller */ + new_profile = find_attach(ns, &ns->base.profiles, + name); + break; + case AA_X_TABLE: + /* released by caller */ + new_profile = x_table_lookup(profile, xindex); + break; + } + + /* released by caller */ + return new_profile; +} + +/** + * 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 + */ +int apparmor_bprm_set_creds(struct linux_binprm *bprm) +{ + struct aa_task_cxt *cxt; + struct aa_profile *profile, *new_profile = NULL; + struct aa_namespace *ns; + char *buffer = NULL; + unsigned int state; + struct file_perms perms = {}; + struct path_cond cond = { + bprm->file->f_path.dentry->d_inode->i_uid, + bprm->file->f_path.dentry->d_inode->i_mode + }; + const char *name = NULL, *target = NULL, *info = NULL; + int error = cap_bprm_set_creds(bprm); + if (error) + return error; + + if (bprm->cred_prepared) + return 0; + + cxt = bprm->cred->security; + BUG_ON(!cxt); + + profile = aa_get_profile(aa_newest_version(cxt->profile)); + /* + * get the namespace from the replacement profile as replacement + * can change the namespace + */ + ns = profile->ns; + state = profile->file.start; + + /* buffer freed below, name is pointer into buffer */ + error = aa_get_name(&bprm->file->f_path, profile->path_flags, &buffer, + &name); + if (error) { + if (profile->flags & + (PFLAG_IX_ON_NAME_ERROR | PFLAG_UNCONFINED)) + error = 0; + info = "Exec failed name resolution"; + name = bprm->filename; + goto audit; + } + + /* Test for onexec first as onexec directives override other + * x transitions. + */ + if (unconfined(profile)) { + /* unconfined task */ + if (cxt->onexec) + /* change_profile on exec already been granted */ + new_profile = aa_get_profile(cxt->onexec); + else + new_profile = find_attach(ns, &ns->base.profiles, name); + if (!new_profile) + goto cleanup; + goto apply; + } + + /* find exec permissions for name */ + state = aa_str_perms(profile->file.dfa, state, name, &cond, &perms); + if (cxt->onexec) { + struct file_perms cp; + info = "change_profile onexec"; + if (!(perms.allow & AA_MAY_ONEXEC)) + 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); + cp = change_profile_perms(profile, cxt->onexec->ns, name, + AA_MAY_ONEXEC, state); + + if (!(cp.allow & AA_MAY_ONEXEC)) + goto audit; + new_profile = aa_get_profile(aa_newest_version(cxt->onexec)); + goto apply; + } + + if (perms.allow & MAY_EXEC) { + /* exec permission determine how to transition */ + new_profile = x_to_profile(profile, name, perms.xindex); + if (!new_profile) { + if (perms.xindex & AA_X_INHERIT) { + /* (p|c|n)ix - don't change profile but do + * use the newest version, which was picked + * up above when getting profile + */ + info = "ix fallback"; + new_profile = aa_get_profile(profile); + goto x_clear; + } else if (perms.xindex & AA_X_UNCONFINED) { + new_profile = aa_get_profile(ns->unconfined); + info = "ux fallback"; + } else { + error = -ENOENT; + info = "profile not found"; + } + } + } else if (COMPLAIN_MODE(profile)) { + /* no exec permission - are we in learning mode */ + new_profile = aa_new_null_profile(profile, 0); + if (!new_profile) { + error = -ENOMEM; + info = "could not create null profile"; + } else { + error = -EACCES; + target = new_profile->base.hname; + } + perms.xindex |= AA_X_UNSAFE; + } else + /* fail exec */ + error = -EACCES; + + if (!new_profile) + goto audit; + + if (bprm->unsafe & LSM_UNSAFE_SHARE) { + /* FIXME: currently don't mediate shared state */ + ; + } + + if (bprm->unsafe & (LSM_UNSAFE_PTRACE | LSM_UNSAFE_PTRACE_CAP)) { + error = may_change_ptraced_domain(current, new_profile); + if (error) { + aa_put_profile(new_profile); + goto audit; + } + } + + /* Determine if secure exec is needed. + * Can be at this point for the following reasons: + * 1. unconfined switching to confined + * 2. confined switching to different confinement + * 3. confined switching to unconfined + * + * Cases 2 and 3 are marked as requiring secure exec + * (unless policy specified "unsafe exec") + * + * bprm->unsafe is used to cache the AA_X_UNSAFE permission + * to avoid having to recompute in secureexec + */ + if (!(perms.xindex & AA_X_UNSAFE)) { + AA_DEBUG("scrubbing environment variables for %s profile=%s\n", + name, new_profile->base.hname); + bprm->unsafe |= AA_SECURE_X_NEEDED; + } +apply: + target = new_profile->base.hname; + /* when transitioning profiles clear unsafe personality bits */ + bprm->per_clear |= PER_CLEAR_ON_SETID; + +x_clear: + aa_put_profile(cxt->profile); + /* transfer new profile reference will be released when cxt is freed */ + cxt->profile = new_profile; + + /* clear out all temporary/transitional state from the context */ + aa_put_profile(cxt->previous); + aa_put_profile(cxt->onexec); + cxt->previous = NULL; + cxt->onexec = NULL; + cxt->token = 0; + +audit: + error = aa_audit_file(profile, &perms, GFP_KERNEL, OP_EXEC, MAY_EXEC, + name, target, cond.uid, info, error); + +cleanup: + aa_put_profile(profile); + kfree(buffer); + + return error; +} + +/** + * apparmor_bprm_secureexec - determine if secureexec is needed + * @bprm: binprm for exec (NOT NULL) + * + * Returns: %1 if secureexec is needed else %0 + */ +int apparmor_bprm_secureexec(struct linux_binprm *bprm) +{ + int ret = cap_bprm_secureexec(bprm); + + /* the decision to use secure exec is computed in set_creds + * and stored in bprm->unsafe. + */ + if (!ret && (bprm->unsafe & AA_SECURE_X_NEEDED)) + ret = 1; + + return ret; +} + +/** + * apparmor_bprm_committing_creds - do task cleanup on committing new creds + * @bprm: binprm for the exec (NOT NULL) + */ +void apparmor_bprm_committing_creds(struct linux_binprm *bprm) +{ + struct aa_profile *profile = __aa_current_profile(); + struct aa_task_cxt *new_cxt = bprm->cred->security; + + /* bail out if unconfined or not changing profile */ + if ((new_cxt->profile == profile) || + (unconfined(new_cxt->profile))) + return; + + current->pdeath_signal = 0; + + /* reset soft limits and set hard limits for the new profile */ + __aa_transition_rlimits(profile, new_cxt->profile); +} + +/** + * apparmor_bprm_commited_cred - do cleanup after new creds committed + * @bprm: binprm for the exec (NOT NULL) + */ +void apparmor_bprm_committed_creds(struct linux_binprm *bprm) +{ + /* TODO: cleanup signals - ipc mediation */ + return; +} + +/* + * Functions for self directed profile change + */ + +/** + * new_compound_name - create an hname with @n2 appended to @n1 + * @n1: base of hname (NOT NULL) + * @n2: name to append (NOT NULL) + * + * Returns: new name or NULL on error + */ +static char *new_compound_name(const char *n1, const char *n2) +{ + char *name = kmalloc(strlen(n1) + strlen(n2) + 3, GFP_KERNEL); + if (name) + sprintf(name, "%s//%s", n1, n2); + return name; +} + +/** + * 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 + * @permtest: true if this is just a permission test + * + * 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. + * + * Returns %0 on success, error otherwise. + */ +int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) +{ + const struct cred *cred; + struct aa_task_cxt *cxt; + struct aa_profile *profile, *previous_profile, *hat = NULL; + char *name = NULL; + int i; + struct file_perms perms = {}; + const char *target = NULL, *info = NULL; + int error = 0; + + /* released below */ + cred = get_current_cred(); + cxt = cred->security; + profile = aa_cred_profile(cred); + previous_profile = cxt->previous; + + if (unconfined(profile)) { + info = "unconfined"; + error = -EPERM; + goto audit; + } + + if (count) { + /* attempting to change into a new hat or switch to a sibling */ + struct aa_profile *root; + root = PROFILE_IS_HAT(profile) ? profile->parent : profile; + + /* find first matching hat */ + for (i = 0; i < count && !hat; i++) + /* released below */ + hat = aa_find_child(root, hats[i]); + if (!hat) { + if (!COMPLAIN_MODE(root) || permtest) { + if (list_empty(&root->base.profiles)) + error = -ECHILD; + else + error = -ENOENT; + goto out; + } + + /* + * In complain mode and failed to match any hats. + * Audit the failure is based off of the first hat + * supplied. This is done due how userspace + * interacts with change_hat. + * + * TODO: Add logging of all failed hats + */ + + /* freed below */ + name = new_compound_name(root->base.hname, hats[0]); + target = name; + /* released below */ + hat = aa_new_null_profile(profile, 1); + if (!hat) { + info = "failed null profile create"; + error = -ENOMEM; + goto audit; + } + } else { + target = hat->base.hname; + if (!PROFILE_IS_HAT(hat)) { + info = "target not hat"; + error = -EPERM; + goto audit; + } + } + + error = may_change_ptraced_domain(current, hat); + if (error) { + info = "ptraced"; + error = -EPERM; + goto audit; + } + + if (!permtest) { + error = aa_set_current_hat(hat, token); + if (error == -EACCES) + /* kill task in case of brute force attacks */ + perms.kill = AA_MAY_CHANGEHAT; + else if (name && !error) + /* reset error for learning of new hats */ + error = -ENOENT; + } + } else if (previous_profile) { + /* Return to saved profile. Kill task if restore fails + * to avoid brute force attacks + */ + target = previous_profile->base.hname; + error = aa_restore_previous_profile(token); + perms.kill = AA_MAY_CHANGEHAT; + } else + /* ignore restores when there is no saved profile */ + goto out; + +audit: + if (!permtest) + error = aa_audit_file(profile, &perms, GFP_KERNEL, + OP_CHANGE_HAT, AA_MAY_CHANGEHAT, NULL, + target, 0, info, error); + +out: + aa_put_profile(hat); + kfree(name); + put_cred(cred); + + return error; +} + +/** + * aa_change_profile - perform a one-way profile transition + * @ns_name: name of the profile namespace to change to (MAYBE NULL) + * @hname: name of profile to change to (MAYBE NULL) + * @onexec: whether this transition is to take place immediately or at exec + * @permtest: true if this is just a permission test + * + * 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 *ns_name, const char *hname, bool onexec, + bool permtest) +{ + const struct cred *cred; + struct aa_task_cxt *cxt; + struct aa_profile *profile, *target = NULL; + struct aa_namespace *ns = NULL; + struct file_perms perms = {}; + const char *name = NULL, *info = NULL; + int op, error = 0; + u32 request; + + if (!hname && !ns_name) + return -EINVAL; + + if (onexec) { + request = AA_MAY_ONEXEC; + op = OP_CHANGE_ONEXEC; + } else { + request = AA_MAY_CHANGE_PROFILE; + op = OP_CHANGE_PROFILE; + } + + cred = get_current_cred(); + cxt = cred->security; + profile = aa_cred_profile(cred); + + if (ns_name) { + /* released below */ + ns = aa_find_namespace(profile->ns, ns_name); + if (!ns) { + /* we don't create new namespace in complain mode */ + name = ns_name; + info = "namespace not found"; + error = -ENOENT; + goto audit; + } + } else + /* released below */ + ns = aa_get_namespace(profile->ns); + + /* if the name was not specified, use the name of the current profile */ + if (!hname) { + if (unconfined(profile)) + hname = ns->unconfined->base.hname; + else + hname = profile->base.hname; + } + + perms = change_profile_perms(profile, ns, hname, request, + profile->file.start); + if (!(perms.allow & request)) { + error = -EACCES; + goto audit; + } + + /* released below */ + target = aa_lookup_profile(ns, hname); + if (!target) { + info = "profile not found"; + error = -ENOENT; + if (permtest || !COMPLAIN_MODE(profile)) + goto audit; + /* released below */ + target = aa_new_null_profile(profile, 0); + if (!target) { + info = "failed null profile create"; + error = -ENOMEM; + goto audit; + } + } + + /* check if tracing task is allowed to trace target domain */ + error = may_change_ptraced_domain(current, target); + if (error) { + info = "ptrace prevents transition"; + goto audit; + } + + if (permtest) + goto audit; + + if (onexec) + error = aa_set_current_onexec(target); + else + error = aa_replace_current_profile(target); + +audit: + if (!permtest) + error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request, + name, hname, 0, info, error); + + aa_put_namespace(ns); + aa_put_profile(target); + put_cred(cred); + + return error; +} |