/* * AppArmor security module * * This file contains AppArmor functions for unpacking policy loaded from * userspace. * * Copyright (C) 1998-2008 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. * * AppArmor uses a serialized binary format for loading policy. To find * policy format documentation look in Documentation/security/apparmor.txt * All policy is validated before it is used. */ #include #include #include #include "include/apparmor.h" #include "include/audit.h" #include "include/context.h" #include "include/crypto.h" #include "include/match.h" #include "include/policy.h" #include "include/policy_unpack.h" #define K_ABI_MASK 0x3ff #define FORCE_COMPLAIN_FLAG 0x800 #define VERSION_LT(X, Y) (((X) & K_ABI_MASK) < ((Y) & K_ABI_MASK)) #define VERSION_GT(X, Y) (((X) & K_ABI_MASK) > ((Y) & K_ABI_MASK)) #define v5 5 /* base version */ #define v6 6 /* per entry policydb mediation check */ #define v7 7 /* full network masking */ /* * The AppArmor interface treats data as a type byte followed by the * actual data. The interface has the notion of a a named entry * which has a name (AA_NAME typecode followed by name string) followed by * the entries typecode and data. Named types allow for optional * elements and extensions to be added and tested for without breaking * backwards compatibility. */ enum aa_code { AA_U8, AA_U16, AA_U32, AA_U64, AA_NAME, /* same as string except it is items name */ AA_STRING, AA_BLOB, AA_STRUCT, AA_STRUCTEND, AA_LIST, AA_LISTEND, AA_ARRAY, AA_ARRAYEND, }; /* * aa_ext is the read of the buffer containing the serialized profile. The * data is copied into a kernel buffer in apparmorfs and then handed off to * the unpack routines. */ struct aa_ext { void *start; void *end; void *pos; /* pointer to current position in the buffer */ u32 version; }; /* audit callback for unpack fields */ static void audit_cb(struct audit_buffer *ab, void *va) { struct common_audit_data *sa = va; if (sa->aad->iface.target) { struct aa_profile *name = sa->aad->iface.target; audit_log_format(ab, " name="); audit_log_untrustedstring(ab, name->base.hname); } if (sa->aad->iface.pos) audit_log_format(ab, " offset=%ld", sa->aad->iface.pos); } /** * audit_iface - do audit message for policy unpacking/load/replace/remove * @new: profile if it has been allocated (MAYBE NULL) * @name: name of the profile being manipulated (MAYBE NULL) * @info: any extra info about the failure (MAYBE NULL) * @e: buffer position info * @error: error code * * Returns: %0 or error */ static int audit_iface(struct aa_profile *new, const char *name, const char *info, struct aa_ext *e, int error) { struct aa_profile *profile = __aa_current_profile(); struct common_audit_data sa; struct apparmor_audit_data aad = {0,}; sa.type = LSM_AUDIT_DATA_NONE; sa.aad = &aad; if (e) aad.iface.pos = e->pos - e->start; aad.iface.target = new; aad.name = name; aad.info = info; aad.error = error; return aa_audit(AUDIT_APPARMOR_STATUS, profile, GFP_KERNEL, &sa, audit_cb); } void aa_loaddata_kref(struct kref *kref) { struct aa_loaddata *d = container_of(kref, struct aa_loaddata, count); if (d) { kzfree(d->hash); kvfree(d); } } /* test if read will be in packed data bounds */ static bool inbounds(struct aa_ext *e, size_t size) { return (size <= e->end - e->pos); } /** * aa_u16_chunck - test and do bounds checking for a u16 size based chunk * @e: serialized data read head (NOT NULL) * @chunk: start address for chunk of data (NOT NULL) * * Returns: the size of chunk found with the read head at the end of the chunk. */ static size_t unpack_u16_chunk(struct aa_ext *e, char **chunk) { size_t size = 0; if (!inbounds(e, sizeof(u16))) return 0; size = le16_to_cpu(get_unaligned((u16 *) e->pos)); e->pos += sizeof(u16); if (!inbounds(e, size)) return 0; *chunk = e->pos; e->pos += size; return size; } /* unpack control byte */ static bool unpack_X(struct aa_ext *e, enum aa_code code) { if (!inbounds(e, 1)) return 0; if (*(u8 *) e->pos != code) return 0; e->pos++; return 1; } /** * unpack_nameX - check is the next element is of type X with a name of @name * @e: serialized data extent information (NOT NULL) * @code: type code * @name: name to match to the serialized element. (MAYBE NULL) * * check that the next serialized data element is of type X and has a tag * name @name. If @name is specified then there must be a matching * name element in the stream. If @name is NULL any name element will be * skipped and only the typecode will be tested. * * Returns 1 on success (both type code and name tests match) and the read * head is advanced past the headers * * Returns: 0 if either match fails, the read head does not move */ static bool unpack_nameX(struct aa_ext *e, enum aa_code code, const char *name) { /* * May need to reset pos if name or type doesn't match */ void *pos = e->pos; /* * Check for presence of a tagname, and if present name size * AA_NAME tag value is a u16. */ if (unpack_X(e, AA_NAME)) { char *tag = NULL; size_t size = unpack_u16_chunk(e, &tag); /* if a name is specified it must match. otherwise skip tag */ if (name && (!size || strcmp(name, tag))) goto fail; } else if (name) { /* if a name is specified and there is no name tag fail */ goto fail; } /* now check if type code matches */ if (unpack_X(e, code)) return 1; fail: e->pos = pos; return 0; } static bool unpack_u32(struct aa_ext *e, u32 *data, const char *name) { if (unpack_nameX(e, AA_U32, name)) { if (!inbounds(e, sizeof(u32))) return 0; if (data) *data = le32_to_cpu(get_unaligned((u32 *) e->pos)); e->pos += sizeof(u32); return 1; } return 0; } static bool unpack_u64(struct aa_ext *e, u64 *data, const char *name) { if (unpack_nameX(e, AA_U64, name)) { if (!inbounds(e, sizeof(u64))) return 0; if (data) *data = le64_to_cpu(get_unaligned((u64 *) e->pos)); e->pos += sizeof(u64); return 1; } return 0; } static size_t unpack_array(struct aa_ext *e, const char *name) { if (unpack_nameX(e, AA_ARRAY, name)) { int size; if (!inbounds(e, sizeof(u16))) return 0; size = (int)le16_to_cpu(get_unaligned((u16 *) e->pos)); e->pos += sizeof(u16); return size; } return 0; } static size_t unpack_blob(struct aa_ext *e, char **blob, const char *name) { if (unpack_nameX(e, AA_BLOB, name)) { u32 size; if (!inbounds(e, sizeof(u32))) return 0; size = le32_to_cpu(get_unaligned((u32 *) e->pos)); e->pos += sizeof(u32); if (inbounds(e, (size_t) size)) { *blob = e->pos; e->pos += size; return size; } } return 0; } static int unpack_str(struct aa_ext *e, const char **string, const char *name) { char *src_str; size_t size = 0; void *pos = e->pos; *string = NULL; if (unpack_nameX(e, AA_STRING, name)) { size = unpack_u16_chunk(e, &src_str); if (size) { /* strings are null terminated, length is size - 1 */ if (src_str[size - 1] != 0) goto fail; *string = src_str; } } return size; fail: e->pos = pos; return 0; } static int unpack_strdup(struct aa_ext *e, char **string, const char *name) { const char *tmp; void *pos = e->pos; int res = unpack_str(e, &tmp, name); *string = NULL; if (!res) return 0; *string = kmemdup(tmp, res, GFP_KERNEL); if (!*string) { e->pos = pos; return 0; } return res; } #define DFA_VALID_PERM_MASK 0xffffffff #define DFA_VALID_PERM2_MASK 0xffffffff /** * verify_accept - verify the accept tables of a dfa * @dfa: dfa to verify accept tables of (NOT NULL) * @flags: flags governing dfa * * Returns: 1 if valid accept tables else 0 if error */ static bool verify_accept(struct aa_dfa *dfa, int flags) { int i; /* verify accept permissions */ for (i = 0; i < dfa->tables[YYTD_ID_ACCEPT]->td_lolen; i++) { int mode = ACCEPT_TABLE(dfa)[i]; if (mode & ~DFA_VALID_PERM_MASK) return 0; if (ACCEPT_TABLE2(dfa)[i] & ~DFA_VALID_PERM2_MASK) return 0; } return 1; } /** * unpack_dfa - unpack a file rule dfa * @e: serialized data extent information (NOT NULL) * * returns dfa or ERR_PTR or NULL if no dfa */ static struct aa_dfa *unpack_dfa(struct aa_ext *e) { char *blob = NULL; size_t size; struct aa_dfa *dfa = NULL; size = unpack_blob(e, &blob, "aadfa"); if (size) { /* * The dfa is aligned with in the blob to 8 bytes * from the beginning of the stream. * alignment adjust needed by dfa unpack */ size_t sz = blob - (char *) e->start - ((e->pos - e->start) & 7); size_t pad = ALIGN(sz, 8) - sz; int flags = TO_ACCEPT1_FLAG(YYTD_DATA32) | TO_ACCEPT2_FLAG(YYTD_DATA32) | DFA_FLAG_VERIFY_STATES; dfa = aa_dfa_unpack(blob + pad, size - pad, flags); if (IS_ERR(dfa)) return dfa; if (!verify_accept(dfa, flags)) goto fail; } return dfa; fail: aa_put_dfa(dfa); return ERR_PTR(-EPROTO); } /** * unpack_trans_table - unpack a profile transition table * @e: serialized data extent information (NOT NULL) * @profile: profile to add the accept table to (NOT NULL) * * Returns: 1 if table successfully unpacked */ static bool unpack_trans_table(struct aa_ext *e, struct aa_profile *profile) { void *pos = e->pos; /* exec table is optional */ if (unpack_nameX(e, AA_STRUCT, "xtable")) { int i, size; size = unpack_array(e, NULL); /* currently 4 exec bits and entries 0-3 are reserved iupcx */ if (size > 16 - 4) goto fail; profile->file.trans.table = kzalloc(sizeof(char *) * size, GFP_KERNEL); if (!profile->file.trans.table) goto fail; profile->file.trans.size = size; for (i = 0; i < size; i++) { char *str; int c, j, size2 = unpack_strdup(e, &str, NULL); /* unpack_strdup verifies that the last character is * null termination byte. */ if (!size2) goto fail; profile->file.trans.table[i] = str; /* verify that name doesn't start with space */ if (isspace(*str)) goto fail; /* count internal # of internal \0 */ for (c = j = 0; j < size2 - 2; j++) { if (!str[j]) c++; } if (*str == ':') { /* beginning with : requires an embedded \0, * verify that exactly 1 internal \0 exists * trailing \0 already verified by unpack_strdup */ if (c != 1) goto fail; /* first character after : must be valid */ if (!str[1]) goto fail; } else if (c) /* fail - all other cases with embedded \0 */ goto fail; } if (!unpack_nameX(e, AA_ARRAYEND, NULL)) goto fail; if (!unpack_nameX(e, AA_STRUCTEND, NULL)) goto fail; } return 1; fail: aa_free_domain_entries(&profile->file.trans); e->pos = pos; return 0; } static bool unpack_rlimits(struct aa_ext *e, struct aa_profile *profile) { void *pos = e->pos; /* rlimits are optional */ if (unpack_nameX(e, AA_STRUCT, "rlimits")) { int i, size; u32 tmp = 0; if (!unpack_u32(e, &tmp, NULL)) goto fail; profile->rlimits.mask = tmp; size = unpack_array(e, NULL); if (size > RLIM_NLIMITS) goto fail; for (i = 0; i < size; i++) { u64 tmp2 = 0; int a = aa_map_resource(i); if (!unpack_u64(e, &tmp2, NULL)) goto fail; profile->rlimits.limits[a].rlim_max = tmp2; } if (!unpack_nameX(e, AA_ARRAYEND, NULL)) goto fail; if (!unpack_nameX(e, AA_STRUCTEND, NULL)) goto fail; } return 1; fail: e->pos = pos; return 0; } /** * unpack_profile - unpack a serialized profile * @e: serialized data extent information (NOT NULL) * * NOTE: unpack profile sets audit struct if there is a failure */ static struct aa_profile *unpack_profile(struct aa_ext *e) { struct aa_profile *profile = NULL; const char *name = NULL; int i, error = -EPROTO; kernel_cap_t tmpcap; u32 tmp; /* check that we have the right struct being passed */ if (!unpack_nameX(e, AA_STRUCT, "profile")) goto fail; if (!unpack_str(e, &name, NULL)) goto fail; profile = aa_alloc_profile(name, GFP_KERNEL); if (!profile) return ERR_PTR(-ENOMEM); /* profile renaming is optional */ (void) unpack_str(e, &profile->rename, "rename"); /* attachment string is optional */ (void) unpack_str(e, &profile->attach, "attach"); /* xmatch is optional and may be NULL */ profile->xmatch = unpack_dfa(e); if (IS_ERR(profile->xmatch)) { error = PTR_ERR(profile->xmatch); profile->xmatch = NULL; goto fail; } /* xmatch_len is not optional if xmatch is set */ if (profile->xmatch) { if (!unpack_u32(e, &tmp, NULL)) goto fail; profile->xmatch_len = tmp; } /* per profile debug flags (complain, audit) */ if (!unpack_nameX(e, AA_STRUCT, "flags")) goto fail; if (!unpack_u32(e, &tmp, NULL)) goto fail; if (tmp & PACKED_FLAG_HAT) profile->flags |= PFLAG_HAT; if (!unpack_u32(e, &tmp, NULL)) goto fail; if (tmp == PACKED_MODE_COMPLAIN || (e->version & FORCE_COMPLAIN_FLAG)) profile->mode = APPARMOR_COMPLAIN; else if (tmp == PACKED_MODE_KILL) profile->mode = APPARMOR_KILL; else if (tmp == PACKED_MODE_UNCONFINED) profile->mode = APPARMOR_UNCONFINED; if (!unpack_u32(e, &tmp, NULL)) goto fail; if (tmp) profile->audit = AUDIT_ALL; if (!unpack_nameX(e, AA_STRUCTEND, NULL)) goto fail; /* path_flags is optional */ if (unpack_u32(e, &profile->path_flags, "path_flags")) profile->path_flags |= profile->flags & PFLAG_MEDIATE_DELETED; else /* set a default value if path_flags field is not present */ profile->path_flags = PFLAG_MEDIATE_DELETED; if (!unpack_u32(e, &(profile->caps.allow.cap[0]), NULL)) goto fail; if (!unpack_u32(e, &(profile->caps.audit.cap[0]), NULL)) goto fail; if (!unpack_u32(e, &(profile->caps.quiet.cap[0]), NULL)) goto fail; if (!unpack_u32(e, &tmpcap.cap[0], NULL)) goto fail; if (unpack_nameX(e, AA_STRUCT, "caps64")) { /* optional upper half of 64 bit caps */ if (!unpack_u32(e, &(profile->caps.allow.cap[1]), NULL)) goto fail; if (!unpack_u32(e, &(profile->caps.audit.cap[1]), NULL)) goto fail; if (!unpack_u32(e, &(profile->caps.quiet.cap[1]), NULL)) goto fail; if (!unpack_u32(e, &(tmpcap.cap[1]), NULL)) goto fail; if (!unpack_nameX(e, AA_STRUCTEND, NULL)) goto fail; } if (unpack_nameX(e, AA_STRUCT, "capsx")) { /* optional extended caps mediation mask */ if (!unpack_u32(e, &(profile->caps.extended.cap[0]), NULL)) goto fail; if (!unpack_u32(e, &(profile->caps.extended.cap[1]), NULL)) goto fail; if (!unpack_nameX(e, AA_STRUCTEND, NULL)) goto fail; } if (!unpack_rlimits(e, profile)) goto fail; if (unpack_nameX(e, AA_STRUCT, "policydb")) { /* generic policy dfa - optional and may be NULL */ profile->policy.dfa = unpack_dfa(e); if (IS_ERR(profile->policy.dfa)) { error = PTR_ERR(profile->policy.dfa); profile->policy.dfa = NULL; goto fail; } else if (!profile->policy.dfa) { error = -EPROTO; goto fail; } if (!unpack_u32(e, &profile->policy.start[0], "start")) /* default start state */ profile->policy.start[0] = DFA_START; /* setup class index */ for (i = AA_CLASS_FILE; i <= AA_CLASS_LAST; i++) { profile->policy.start[i] = aa_dfa_next(profile->policy.dfa, profile->policy.start[0], i); } if (!unpack_nameX(e, AA_STRUCTEND, NULL)) goto fail; } else profile->policy.dfa = aa_get_dfa(nulldfa); /* get file rules */ profile->file.dfa = unpack_dfa(e); if (IS_ERR(profile->file.dfa)) { error = PTR_ERR(profile->file.dfa); profile->file.dfa = NULL; goto fail; } else if (profile->file.dfa) { if (!unpack_u32(e, &profile->file.start, "dfa_start")) /* default start state */ profile->file.start = DFA_START; } else if (profile->policy.dfa && profile->policy.start[AA_CLASS_FILE]) { profile->file.dfa = aa_get_dfa(profile->policy.dfa); profile->file.start = profile->policy.start[AA_CLASS_FILE]; } else profile->file.dfa = aa_get_dfa(nulldfa); if (!unpack_trans_table(e, profile)) goto fail; if (!unpack_nameX(e, AA_STRUCTEND, NULL)) goto fail; return profile; fail: if (profile) name = NULL; else if (!name) name = "unknown"; audit_iface(profile, name, "failed to unpack profile", e, error); aa_free_profile(profile); return ERR_PTR(error); } /** * verify_head - unpack serialized stream header * @e: serialized data read head (NOT NULL) * @required: whether the header is required or optional * @ns: Returns - namespace if one is specified else NULL (NOT NULL) * * Returns: error or 0 if header is good */ static int verify_header(struct aa_ext *e, int required, const char **ns) { int error = -EPROTONOSUPPORT; const char *name = NULL; *ns = NULL; /* get the interface version */ if (!unpack_u32(e, &e->version, "version")) { if (required) { audit_iface(NULL, NULL, "invalid profile format", e, error); return error; } } /* Check that the interface version is currently supported. * if not specified use previous version * Mask off everything that is not kernel abi version */ if (VERSION_LT(e->version, v5) && VERSION_GT(e->version, v7)) { audit_iface(NULL, NULL, "unsupported interface version", e, error); return error; } /* read the namespace if present */ if (unpack_str(e, &name, "namespace")) { if (*ns && strcmp(*ns, name)) audit_iface(NULL, NULL, "invalid ns change", e, error); else if (!*ns) *ns = name; } return 0; } static bool verify_xindex(int xindex, int table_size) { int index, xtype; xtype = xindex & AA_X_TYPE_MASK; index = xindex & AA_X_INDEX_MASK; if (xtype == AA_X_TABLE && index >= table_size) return 0; return 1; } /* verify dfa xindexes are in range of transition tables */ static bool verify_dfa_xindex(struct aa_dfa *dfa, int table_size) { int i; for (i = 0; i < dfa->tables[YYTD_ID_ACCEPT]->td_lolen; i++) { if (!verify_xindex(dfa_user_xindex(dfa, i), table_size)) return 0; if (!verify_xindex(dfa_other_xindex(dfa, i), table_size)) return 0; } return 1; } /** * verify_profile - Do post unpack analysis to verify profile consistency * @profile: profile to verify (NOT NULL) * * Returns: 0 if passes verification else error */ static int verify_profile(struct aa_profile *profile) { if (profile->file.dfa && !verify_dfa_xindex(profile->file.dfa, profile->file.trans.size)) { audit_iface(profile, NULL, "Invalid named transition", NULL, -EPROTO); return -EPROTO; } return 0; } void aa_load_ent_free(struct aa_load_ent *ent) { if (ent) { aa_put_profile(ent->rename); aa_put_profile(ent->old); aa_put_profile(ent->new); kzfree(ent); } } struct aa_load_ent *aa_load_ent_alloc(void) { struct aa_load_ent *ent = kzalloc(sizeof(*ent), GFP_KERNEL); if (ent) INIT_LIST_HEAD(&ent->list); return ent; } /** * aa_unpack - unpack packed binary profile(s) data loaded from user space * @udata: user data copied to kmem (NOT NULL) * @lh: list to place unpacked profiles in a aa_repl_ws * @ns: Returns namespace profile is in if specified else NULL (NOT NULL) * * Unpack user data and return refcounted allocated profile(s) stored in * @lh in order of discovery, with the list chain stored in base.list * or error * * Returns: profile(s) on @lh else error pointer if fails to unpack */ int aa_unpack(struct aa_loaddata *udata, struct list_head *lh, const char **ns) { struct aa_load_ent *tmp, *ent; struct aa_profile *profile = NULL; int error; struct aa_ext e = { .start = udata->data, .end = udata->data + udata->size, .pos = udata->data, }; *ns = NULL; while (e.pos < e.end) { void *start; error = verify_header(&e, e.pos == e.start, ns); if (error) goto fail; start = e.pos; profile = unpack_profile(&e); if (IS_ERR(profile)) { error = PTR_ERR(profile); goto fail; } error = verify_profile(profile); if (error) goto fail_profile; error = aa_calc_profile_hash(profile, e.version, start, e.pos - start); if (error) goto fail_profile; ent = aa_load_ent_alloc(); if (!ent) { error = -ENOMEM; goto fail_profile; } ent->new = profile; list_add_tail(&ent->list, lh); } udata->abi = e.version & K_ABI_MASK; udata->hash = aa_calc_hash(udata->data, udata->size); if (IS_ERR(udata->hash)) { error = PTR_ERR(udata->hash); udata->hash = NULL; goto fail; } return 0; fail_profile: aa_put_profile(profile); fail: list_for_each_entry_safe(ent, tmp, lh, list) { list_del_init(&ent->list); aa_load_ent_free(ent); } return error; }