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-rw-r--r--security/apparmor/policy_unpack.c703
1 files changed, 703 insertions, 0 deletions
diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
new file mode 100644
index 00000000..d6d9a57b
--- /dev/null
+++ b/security/apparmor/policy_unpack.c
@@ -0,0 +1,703 @@
+/*
+ * 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 <asm/unaligned.h>
+#include <linux/ctype.h>
+#include <linux/errno.h>
+
+#include "include/apparmor.h"
+#include "include/audit.h"
+#include "include/context.h"
+#include "include/match.h"
+#include "include/policy.h"
+#include "include/policy_unpack.h"
+#include "include/sid.h"
+
+/*
+ * 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 (NOT NULL)
+ * @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;
+ COMMON_AUDIT_DATA_INIT(&sa, NONE);
+ sa.aad.iface.pos = e->pos - e->start;
+ sa.aad.iface.target = new;
+ sa.aad.name = name;
+ sa.aad.info = info;
+ sa.aad.error = error;
+
+ return aa_audit(AUDIT_APPARMOR_STATUS, profile, GFP_KERNEL, &sa,
+ audit_cb);
+}
+
+/* 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;
+}
+
+/**
+ * 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.
+ */
+ size_t sz = blob - (char *)e->start;
+ size_t pad = ALIGN(sz, 8) - sz;
+ int flags = TO_ACCEPT1_FLAG(YYTD_DATA32) |
+ TO_ACCEPT2_FLAG(YYTD_DATA32);
+
+
+ if (aa_g_paranoid_load)
+ flags |= 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, size = unpack_strdup(e, &str, NULL);
+ /* unpack_strdup verifies that the last character is
+ * null termination byte.
+ */
+ if (!size)
+ 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 < size - 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 tmp = 0;
+ int a = aa_map_resource(i);
+ if (!unpack_u64(e, &tmp, NULL))
+ goto fail;
+ profile->rlimits.limits[a].rlim_max = tmp;
+ }
+ 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 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);
+ if (!profile)
+ return ERR_PTR(-ENOMEM);
+
+ /* profile renaming is optional */
+ (void) unpack_str(e, &profile->rename, "rename");
+
+ /* 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)
+ profile->flags |= PFLAG_HAT;
+ if (!unpack_u32(e, &tmp, NULL))
+ goto fail;
+ if (tmp)
+ profile->mode = APPARMOR_COMPLAIN;
+ 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_rlimits(e, profile))
+ goto fail;
+
+ /* 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;
+ }
+
+ if (!unpack_u32(e, &profile->file.start, "dfa_start"))
+ /* default start state */
+ profile->file.start = DFA_START;
+
+ 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_put_profile(profile);
+
+ return ERR_PTR(error);
+}
+
+/**
+ * verify_head - unpack serialized stream header
+ * @e: serialized data read head (NOT NULL)
+ * @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, const char **ns)
+{
+ int error = -EPROTONOSUPPORT;
+ /* get the interface version */
+ if (!unpack_u32(e, &e->version, "version")) {
+ audit_iface(NULL, NULL, "invalid profile format", e, error);
+ return error;
+ }
+
+ /* check that the interface version is currently supported */
+ if (e->version != 5) {
+ audit_iface(NULL, NULL, "unsupported interface version", e,
+ error);
+ return error;
+ }
+
+ /* read the namespace if present */
+ if (!unpack_str(e, ns, "namespace"))
+ *ns = NULL;
+
+ 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 (aa_g_paranoid_load) {
+ 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;
+}
+
+/**
+ * aa_unpack - unpack packed binary profile data loaded from user space
+ * @udata: user data copied to kmem (NOT NULL)
+ * @size: the size of the user data
+ * @ns: Returns namespace profile is in if specified else NULL (NOT NULL)
+ *
+ * Unpack user data and return refcounted allocated profile or ERR_PTR
+ *
+ * Returns: profile else error pointer if fails to unpack
+ */
+struct aa_profile *aa_unpack(void *udata, size_t size, const char **ns)
+{
+ struct aa_profile *profile = NULL;
+ int error;
+ struct aa_ext e = {
+ .start = udata,
+ .end = udata + size,
+ .pos = udata,
+ };
+
+ error = verify_header(&e, ns);
+ if (error)
+ return ERR_PTR(error);
+
+ profile = unpack_profile(&e);
+ if (IS_ERR(profile))
+ return profile;
+
+ error = verify_profile(profile);
+ if (error) {
+ aa_put_profile(profile);
+ profile = ERR_PTR(error);
+ }
+
+ /* return refcount */
+ return profile;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-10-31 23:04:41 +0000