// SPDX-License-Identifier: GPL-2.0-only /* * AppArmor security module * * This file contains AppArmor af_unix fine grained mediation * * Copyright 2023 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 #include #include "include/audit.h" #include "include/af_unix.h" #include "include/apparmor.h" #include "include/file.h" #include "include/label.h" #include "include/path.h" #include "include/policy.h" #include "include/cred.h" static inline struct sock *aa_unix_sk(struct unix_sock *u) { return &u->sk; } static int unix_fs_perm(const char *op, u32 mask, const struct cred *subj_cred, struct aa_label *label, struct path *path) { AA_BUG(!label); AA_BUG(!path); if (unconfined(label) || !label_mediates(label, AA_CLASS_FILE)) return 0; mask &= NET_FS_PERMS; /* if !u->path.dentry socket is being shutdown - implicit delegation * until obj delegation is supported */ if (path->dentry) { /* the sunpath may not be valid for this ns so use the path */ struct inode *inode = path->dentry->d_inode; vfsuid_t vfsuid = i_uid_into_vfsuid(mnt_idmap(path->mnt), inode); struct path_cond cond = { .uid = vfsuid_into_kuid(vfsuid), .mode = inode->i_mode, }; return aa_path_perm(op, subj_cred, label, path, PATH_SOCK_COND, mask, &cond); } /* else implicitly delegated */ return 0; } /* match_addr special constants */ #define ABSTRACT_ADDR "\x00" /* abstract socket addr */ #define ANONYMOUS_ADDR "\x01" /* anonymous endpoint, no addr */ #define DISCONNECTED_ADDR "\x02" /* addr is another namespace */ #define SHUTDOWN_ADDR "\x03" /* path addr is shutdown and cleared */ #define FS_ADDR "/" /* path addr in fs */ static aa_state_t match_addr(struct aa_dfa *dfa, aa_state_t state, struct sockaddr_un *addr, int addrlen) { if (addr) /* include leading \0 */ state = aa_dfa_match_len(dfa, state, addr->sun_path, unix_addr_len(addrlen)); else state = aa_dfa_match_len(dfa, state, ANONYMOUS_ADDR, 1); /* todo: could change to out of band for cleaner separation */ state = aa_dfa_null_transition(dfa, state); return state; } static aa_state_t match_to_local(struct aa_policydb *policy, aa_state_t state, u32 request, int type, int protocol, struct sockaddr_un *addr, int addrlen, struct aa_perms **p, const char **info) { state = aa_match_to_prot(policy, state, request, PF_UNIX, type, protocol, NULL, info); if (state) { state = match_addr(policy->dfa, state, addr, addrlen); if (state) { /* todo: local label matching */ state = aa_dfa_null_transition(policy->dfa, state); if (!state) *info = "failed local label match"; } else { *info = "failed local address match"; } } return state; } struct sockaddr_un *aa_sunaddr(const struct unix_sock *u, int *addrlen) { struct unix_address *addr; /* memory barrier is sufficient see note in net/unix/af_unix.c */ addr = smp_load_acquire(&u->addr); if (addr) { *addrlen = addr->len; return addr->name; } *addrlen = 0; return NULL; } static aa_state_t match_to_sk(struct aa_policydb *policy, aa_state_t state, u32 request, struct unix_sock *u, struct aa_perms **p, const char **info) { int addrlen; struct sockaddr_un *addr = aa_sunaddr(u, &addrlen); return match_to_local(policy, state, request, u->sk.sk_type, u->sk.sk_protocol, addr, addrlen, p, info); } #define CMD_ADDR 1 #define CMD_LISTEN 2 #define CMD_OPT 4 static aa_state_t match_to_cmd(struct aa_policydb *policy, aa_state_t state, u32 request, struct unix_sock *u, char cmd, struct aa_perms **p, const char **info) { AA_BUG(!p); state = match_to_sk(policy, state, request, u, p, info); if (state && !*p) { state = aa_dfa_match_len(policy->dfa, state, &cmd, 1); if (!state) *info = "failed cmd selection match"; } return state; } static aa_state_t match_to_peer(struct aa_policydb *policy, aa_state_t state, u32 request, struct unix_sock *u, struct sockaddr_un *peer_addr, int peer_addrlen, struct aa_perms **p, const char **info) { AA_BUG(!p); state = match_to_cmd(policy, state, request, u, CMD_ADDR, p, info); if (state && !*p) { state = match_addr(policy->dfa, state, peer_addr, peer_addrlen); if (!state) *info = "failed peer address match"; } return state; } static aa_state_t match_label(struct aa_profile *profile, struct aa_ruleset *rule, aa_state_t state, u32 request, struct aa_profile *peer, struct aa_perms *p, struct apparmor_audit_data *ad) { AA_BUG(!profile); AA_BUG(!peer); ad->peer = &peer->label; if (state && !p) { state = aa_dfa_match(rule->policy->dfa, state, peer->base.hname); if (!state) ad->info = "failed peer label match"; } return aa_do_perms(profile, rule->policy, state, request, p, ad); } /* unix sock creation comes before we know if the socket will be an fs * socket * v6 - semantics are handled by mapping in profile load * v7 - semantics require sock create for tasks creating an fs socket. * v8 - same as v7 */ static int profile_create_perm(struct aa_profile *profile, int family, int type, int protocol, struct apparmor_audit_data *ad) { struct aa_ruleset *rules = profile->label.rules[0]; aa_state_t state; AA_BUG(!profile); AA_BUG(profile_unconfined(profile)); state = RULE_MEDIATES_v9NET(rules); if (state) { state = aa_match_to_prot(rules->policy, state, AA_MAY_CREATE, PF_UNIX, type, protocol, NULL, &ad->info); return aa_do_perms(profile, rules->policy, state, AA_MAY_CREATE, NULL, ad); } return aa_profile_af_perm(profile, ad, AA_MAY_CREATE, family, type, protocol); } static int profile_sk_perm(struct aa_profile *profile, struct apparmor_audit_data *ad, u32 request, struct sock *sk, struct path *path) { struct aa_ruleset *rules = profile->label.rules[0]; struct aa_perms *p = NULL; aa_state_t state; AA_BUG(!profile); AA_BUG(!sk); AA_BUG(profile_unconfined(profile)); state = RULE_MEDIATES_v9NET(rules); if (state) { if (is_unix_fs(sk)) return unix_fs_perm(ad->op, request, ad->subj_cred, &profile->label, &unix_sk(sk)->path); state = match_to_sk(rules->policy, state, request, unix_sk(sk), &p, &ad->info); return aa_do_perms(profile, rules->policy, state, request, p, ad); } return aa_profile_af_sk_perm(profile, ad, request, sk); } static int profile_bind_perm(struct aa_profile *profile, struct sock *sk, struct apparmor_audit_data *ad) { struct aa_ruleset *rules = profile->label.rules[0]; struct aa_perms *p = NULL; aa_state_t state; AA_BUG(!profile); AA_BUG(!sk); AA_BUG(!ad); AA_BUG(profile_unconfined(profile)); state = RULE_MEDIATES_v9NET(rules); if (state) { if (is_unix_addr_fs(ad->net.addr, ad->net.addrlen)) /* under v7-9 fs hook handles bind */ return 0; /* bind for abstract socket */ state = match_to_local(rules->policy, state, AA_MAY_BIND, sk->sk_type, sk->sk_protocol, unix_addr(ad->net.addr), ad->net.addrlen, &p, &ad->info); return aa_do_perms(profile, rules->policy, state, AA_MAY_BIND, p, ad); } return aa_profile_af_sk_perm(profile, ad, AA_MAY_BIND, sk); } static int profile_listen_perm(struct aa_profile *profile, struct sock *sk, int backlog, struct apparmor_audit_data *ad) { struct aa_ruleset *rules = profile->label.rules[0]; struct aa_perms *p = NULL; aa_state_t state; AA_BUG(!profile); AA_BUG(!sk); AA_BUG(!ad); AA_BUG(profile_unconfined(profile)); state = RULE_MEDIATES_v9NET(rules); if (state) { __be16 b = cpu_to_be16(backlog); if (is_unix_fs(sk)) return unix_fs_perm(ad->op, AA_MAY_LISTEN, ad->subj_cred, &profile->label, &unix_sk(sk)->path); state = match_to_cmd(rules->policy, state, AA_MAY_LISTEN, unix_sk(sk), CMD_LISTEN, &p, &ad->info); if (state && !p) { state = aa_dfa_match_len(rules->policy->dfa, state, (char *) &b, 2); if (!state) ad->info = "failed listen backlog match"; } return aa_do_perms(profile, rules->policy, state, AA_MAY_LISTEN, p, ad); } return aa_profile_af_sk_perm(profile, ad, AA_MAY_LISTEN, sk); } static int profile_accept_perm(struct aa_profile *profile, struct sock *sk, struct apparmor_audit_data *ad) { struct aa_ruleset *rules = profile->label.rules[0]; struct aa_perms *p = NULL; aa_state_t state; AA_BUG(!profile); AA_BUG(!sk); AA_BUG(!ad); AA_BUG(profile_unconfined(profile)); state = RULE_MEDIATES_v9NET(rules); if (state) { if (is_unix_fs(sk)) return unix_fs_perm(ad->op, AA_MAY_ACCEPT, ad->subj_cred, &profile->label, &unix_sk(sk)->path); state = match_to_sk(rules->policy, state, AA_MAY_ACCEPT, unix_sk(sk), &p, &ad->info); return aa_do_perms(profile, rules->policy, state, AA_MAY_ACCEPT, p, ad); } return aa_profile_af_sk_perm(profile, ad, AA_MAY_ACCEPT, sk); } static int profile_opt_perm(struct aa_profile *profile, u32 request, struct sock *sk, int optname, struct apparmor_audit_data *ad) { struct aa_ruleset *rules = profile->label.rules[0]; struct aa_perms *p = NULL; aa_state_t state; AA_BUG(!profile); AA_BUG(!sk); AA_BUG(!ad); AA_BUG(profile_unconfined(profile)); state = RULE_MEDIATES_v9NET(rules); if (state) { __be16 b = cpu_to_be16(optname); if (is_unix_fs(sk)) return unix_fs_perm(ad->op, request, ad->subj_cred, &profile->label, &unix_sk(sk)->path); state = match_to_cmd(rules->policy, state, request, unix_sk(sk), CMD_OPT, &p, &ad->info); if (state && !p) { state = aa_dfa_match_len(rules->policy->dfa, state, (char *) &b, 2); if (!state) ad->info = "failed sockopt match"; } return aa_do_perms(profile, rules->policy, state, request, p, ad); } return aa_profile_af_sk_perm(profile, ad, request, sk); } /* null peer_label is allowed, in which case the peer_sk label is used */ static int profile_peer_perm(struct aa_profile *profile, u32 request, struct sock *sk, struct path *path, struct sockaddr_un *peer_addr, int peer_addrlen, struct path *peer_path, struct aa_label *peer_label, struct apparmor_audit_data *ad) { struct aa_ruleset *rules = profile->label.rules[0]; struct aa_perms *p = NULL; aa_state_t state; AA_BUG(!profile); AA_BUG(profile_unconfined(profile)); AA_BUG(!sk); AA_BUG(!peer_label); AA_BUG(!ad); state = RULE_MEDIATES_v9NET(rules); if (state) { struct aa_profile *peerp; if (peer_path) return unix_fs_perm(ad->op, request, ad->subj_cred, &profile->label, peer_path); else if (path) return unix_fs_perm(ad->op, request, ad->subj_cred, &profile->label, path); state = match_to_peer(rules->policy, state, request, unix_sk(sk), peer_addr, peer_addrlen, &p, &ad->info); return fn_for_each_in_ns(peer_label, peerp, match_label(profile, rules, state, request, peerp, p, ad)); } return aa_profile_af_sk_perm(profile, ad, request, sk); } /* -------------------------------- */ int aa_unix_create_perm(struct aa_label *label, int family, int type, int protocol) { if (!unconfined(label)) { struct aa_profile *profile; DEFINE_AUDIT_NET(ad, OP_CREATE, current_cred(), NULL, family, type, protocol); return fn_for_each_confined(label, profile, profile_create_perm(profile, family, type, protocol, &ad)); } return 0; } static int aa_unix_label_sk_perm(const struct cred *subj_cred, struct aa_label *label, const char *op, u32 request, struct sock *sk, struct path *path) { if (!unconfined(label)) { struct aa_profile *profile; DEFINE_AUDIT_SK(ad, op, subj_cred, sk); return fn_for_each_confined(label, profile, profile_sk_perm(profile, &ad, request, sk, path)); } return 0; } /* revalidation, get/set attr, shutdown */ int aa_unix_sock_perm(const char *op, u32 request, struct socket *sock) { struct aa_label *label; int error; label = begin_current_label_crit_section(); error = aa_unix_label_sk_perm(current_cred(), label, op, request, sock->sk, is_unix_fs(sock->sk) ? &unix_sk(sock->sk)->path : NULL); end_current_label_crit_section(label); return error; } static int valid_addr(struct sockaddr *addr, int addr_len) { struct sockaddr_un *sunaddr = unix_addr(addr); /* addr_len == offsetof(struct sockaddr_un, sun_path) is autobind */ if (addr_len < offsetof(struct sockaddr_un, sun_path) || addr_len > sizeof(*sunaddr)) return -EINVAL; return 0; } int aa_unix_bind_perm(struct socket *sock, struct sockaddr *addr, int addrlen) { struct aa_profile *profile; struct aa_label *label; int error = 0; error = valid_addr(addr, addrlen); if (error) return error; label = begin_current_label_crit_section(); /* fs bind is handled by mknod */ if (!unconfined(label)) { DEFINE_AUDIT_SK(ad, OP_BIND, current_cred(), sock->sk); ad.net.addr = unix_addr(addr); ad.net.addrlen = addrlen; error = fn_for_each_confined(label, profile, profile_bind_perm(profile, sock->sk, &ad)); } end_current_label_crit_section(label); return error; } /* * unix connections are covered by the * - unix_stream_connect (stream) and unix_may_send hooks (dgram) * - fs connect is handled by open * This is just here to document this is not needed for af_unix * int aa_unix_connect_perm(struct socket *sock, struct sockaddr *address, int addrlen) { return 0; } */ int aa_unix_listen_perm(struct socket *sock, int backlog) { struct aa_profile *profile; struct aa_label *label; int error = 0; label = begin_current_label_crit_section(); if (!unconfined(label)) { DEFINE_AUDIT_SK(ad, OP_LISTEN, current_cred(), sock->sk); error = fn_for_each_confined(label, profile, profile_listen_perm(profile, sock->sk, backlog, &ad)); } end_current_label_crit_section(label); return error; } /* ability of sock to connect, not peer address binding */ int aa_unix_accept_perm(struct socket *sock, struct socket *newsock) { struct aa_profile *profile; struct aa_label *label; int error = 0; label = begin_current_label_crit_section(); if (!unconfined(label)) { DEFINE_AUDIT_SK(ad, OP_ACCEPT, current_cred(), sock->sk); error = fn_for_each_confined(label, profile, profile_accept_perm(profile, sock->sk, &ad)); } end_current_label_crit_section(label); return error; } /* * dgram handled by unix_may_sendmsg, right to send on stream done at connect * could do per msg unix_stream here, but connect + socket transfer is * sufficient. This is just here to document this is not needed for af_unix * * sendmsg, recvmsg int aa_unix_msg_perm(const char *op, u32 request, struct socket *sock, struct msghdr *msg, int size) { return 0; } */ int aa_unix_opt_perm(const char *op, u32 request, struct socket *sock, int level, int optname) { struct aa_profile *profile; struct aa_label *label; int error = 0; label = begin_current_label_crit_section(); if (!unconfined(label)) { DEFINE_AUDIT_SK(ad, op, current_cred(), sock->sk); error = fn_for_each_confined(label, profile, profile_opt_perm(profile, request, sock->sk, optname, &ad)); } end_current_label_crit_section(label); return error; } static int unix_peer_perm(const struct cred *subj_cred, struct aa_label *label, const char *op, u32 request, struct sock *sk, struct path *path, struct sockaddr_un *peer_addr, int peer_addrlen, struct path *peer_path, struct aa_label *peer_label) { struct aa_profile *profile; DEFINE_AUDIT_SK(ad, op, subj_cred, sk); ad.net.peer.addr = peer_addr; ad.net.peer.addrlen = peer_addrlen; return fn_for_each_confined(label, profile, profile_peer_perm(profile, request, sk, path, peer_addr, peer_addrlen, peer_path, peer_label, &ad)); } /** * * Requires: lock held on both @sk and @peer_sk * called by unix_stream_connect, unix_may_send */ int aa_unix_peer_perm(const struct cred *subj_cred, struct aa_label *label, const char *op, u32 request, struct sock *sk, struct sock *peer_sk, struct aa_label *peer_label) { struct unix_sock *peeru = unix_sk(peer_sk); struct unix_sock *u = unix_sk(sk); int plen; struct sockaddr_un *paddr = aa_sunaddr(unix_sk(peer_sk), &plen); AA_BUG(!label); AA_BUG(!sk); AA_BUG(!peer_sk); AA_BUG(!peer_label); return unix_peer_perm(subj_cred, label, op, request, sk, is_unix_fs(sk) ? &u->path : NULL, paddr, plen, is_unix_fs(peer_sk) ? &peeru->path : NULL, peer_label); } /* sk_plabel for comparison only */ static void update_sk_ctx(struct sock *sk, struct aa_label *label, struct aa_label *plabel) { struct aa_label *l, *old; struct aa_sk_ctx *ctx = aa_sock(sk); bool update_sk; rcu_read_lock(); update_sk = (plabel && (plabel != rcu_access_pointer(ctx->peer_lastupdate) || !aa_label_is_subset(plabel, rcu_dereference(ctx->peer)))) || !__aa_subj_label_is_cached(label, rcu_dereference(ctx->label)); rcu_read_unlock(); if (!update_sk) return; spin_lock(&unix_sk(sk)->lock); old = rcu_dereference_protected(ctx->label, lockdep_is_held(&unix_sk(sk)->lock)); l = aa_label_merge(old, label, GFP_ATOMIC); if (l) { if (l != old) { rcu_assign_pointer(ctx->label, l); aa_put_label(old); } else aa_put_label(l); } if (plabel && rcu_access_pointer(ctx->peer_lastupdate) != plabel) { old = rcu_dereference_protected(ctx->peer, lockdep_is_held(&unix_sk(sk)->lock)); if (old == plabel) { rcu_assign_pointer(ctx->peer_lastupdate, plabel); } else if (aa_label_is_subset(plabel, old)) { rcu_assign_pointer(ctx->peer_lastupdate, plabel); rcu_assign_pointer(ctx->peer, aa_get_label(plabel)); aa_put_label(old); } /* else race or a subset - don't update */ } spin_unlock(&unix_sk(sk)->lock); } static void update_peer_ctx(struct sock *sk, struct aa_sk_ctx *ctx, struct aa_label *label) { struct aa_label *l, *old; spin_lock(&unix_sk(sk)->lock); old = rcu_dereference_protected(ctx->peer, lockdep_is_held(&unix_sk(sk)->lock)); l = aa_label_merge(old, label, GFP_ATOMIC); if (l) { if (l != old) { rcu_assign_pointer(ctx->peer, l); aa_put_label(old); } else aa_put_label(l); } spin_unlock(&unix_sk(sk)->lock); } /* This fn is only checked if something has changed in the security * boundaries. Otherwise cached info off file is sufficient */ int aa_unix_file_perm(const struct cred *subj_cred, struct aa_label *label, const char *op, u32 request, struct file *file) { struct socket *sock = (struct socket *) file->private_data; struct sockaddr_un *addr, *peer_addr; int addrlen, peer_addrlen; struct aa_label *plabel = NULL; struct sock *peer_sk = NULL; u32 sk_req = request & ~NET_PEER_MASK; struct path path; bool is_sk_fs; int error = 0; AA_BUG(!label); AA_BUG(!sock); AA_BUG(!sock->sk); AA_BUG(sock->sk->sk_family != PF_UNIX); /* investigate only using lock via unix_peer_get() * addr only needs the memory barrier, but need to investigate * path */ unix_state_lock(sock->sk); peer_sk = unix_peer(sock->sk); if (peer_sk) sock_hold(peer_sk); is_sk_fs = is_unix_fs(sock->sk); addr = aa_sunaddr(unix_sk(sock->sk), &addrlen); path = unix_sk(sock->sk)->path; unix_state_unlock(sock->sk); if (is_sk_fs && peer_sk) sk_req = request; if (sk_req) { error = aa_unix_label_sk_perm(subj_cred, label, op, sk_req, sock->sk, is_sk_fs ? &path : NULL); } if (!peer_sk) goto out; peer_addr = aa_sunaddr(unix_sk(peer_sk), &peer_addrlen); struct path peer_path; peer_path = unix_sk(peer_sk)->path; if (!is_sk_fs && is_unix_fs(peer_sk)) { last_error(error, unix_fs_perm(op, request, subj_cred, label, is_unix_fs(peer_sk) ? &peer_path : NULL)); } else if (!is_sk_fs) { struct aa_label *plabel; struct aa_sk_ctx *pctx = aa_sock(peer_sk); rcu_read_lock(); plabel = aa_get_label_rcu(&pctx->label); rcu_read_unlock(); /* no fs check of aa_unix_peer_perm because conditions above * ensure they will never be done */ last_error(error, xcheck(unix_peer_perm(subj_cred, label, op, MAY_READ | MAY_WRITE, sock->sk, is_sk_fs ? &path : NULL, peer_addr, peer_addrlen, is_unix_fs(peer_sk) ? &peer_path : NULL, plabel), unix_peer_perm(file->f_cred, plabel, op, MAY_READ | MAY_WRITE, peer_sk, is_unix_fs(peer_sk) ? &peer_path : NULL, addr, addrlen, is_sk_fs ? &path : NULL, label))); if (!error && !__aa_subj_label_is_cached(plabel, label)) update_peer_ctx(peer_sk, pctx, label); } sock_put(peer_sk); out: /* update peer cache to latest successful perm check */ if (error == 0) update_sk_ctx(sock->sk, label, plabel); aa_put_label(plabel); return error; }