![Zubin Mithra](/assets/img/avatar_default.png)
Syzkaller reported a OOB-read with the stacktrace below. This occurs
inside __aa_lookupn_ns as `n` is not initialized. `n` is obtained from
aa_splitn_fqname. In cases where `name` is invalid, aa_splitn_fqname
returns without initializing `ns_name` and `ns_len`.
Fix this by always initializing `ns_name` and `ns_len`.
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
__asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
memcmp+0xe3/0x160 lib/string.c:861
strnstr+0x4b/0x70 lib/string.c:934
__aa_lookupn_ns+0xc1/0x570 security/apparmor/policy_ns.c:209
aa_lookupn_ns+0x88/0x1e0 security/apparmor/policy_ns.c:240
aa_fqlookupn_profile+0x1b9/0x1010 security/apparmor/policy.c:468
fqlookupn_profile+0x80/0xc0 security/apparmor/label.c:1844
aa_label_strn_parse+0xa3a/0x1230 security/apparmor/label.c:1908
aa_label_parse+0x42/0x50 security/apparmor/label.c:1943
aa_change_profile+0x513/0x3510 security/apparmor/domain.c:1362
apparmor_setprocattr+0xaa4/0x1150 security/apparmor/lsm.c:658
security_setprocattr+0x66/0xc0 security/security.c:1298
proc_pid_attr_write+0x301/0x540 fs/proc/base.c:2555
__vfs_write+0x119/0x9f0 fs/read_write.c:485
vfs_write+0x1fc/0x560 fs/read_write.c:549
ksys_write+0x101/0x260 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fixes: 3b0aaf5866
("apparmor: add lib fn to find the "split" for fqnames")
Reported-by: syzbot+61e4b490d9d2da591b50@syzkaller.appspotmail.com
Signed-off-by: Zubin Mithra <zsm@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: John Johansen <john.johansen@canonical.com>
530 lines
13 KiB
C
530 lines
13 KiB
C
/*
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* AppArmor security module
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*
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* This file contains basic common functions used in AppArmor
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*
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* Copyright (C) 1998-2008 Novell/SUSE
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* Copyright 2009-2010 Canonical Ltd.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*/
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#include <linux/ctype.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/vmalloc.h>
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#include "include/audit.h"
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#include "include/apparmor.h"
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#include "include/lib.h"
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#include "include/perms.h"
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#include "include/policy.h"
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struct aa_perms nullperms;
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struct aa_perms allperms = { .allow = ALL_PERMS_MASK,
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.quiet = ALL_PERMS_MASK,
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.hide = ALL_PERMS_MASK };
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/**
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* aa_split_fqname - split a fqname into a profile and namespace name
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* @fqname: a full qualified name in namespace profile format (NOT NULL)
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* @ns_name: pointer to portion of the string containing the ns name (NOT NULL)
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*
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* Returns: profile name or NULL if one is not specified
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*
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* Split a namespace name from a profile name (see policy.c for naming
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* description). If a portion of the name is missing it returns NULL for
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* that portion.
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*
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* NOTE: may modify the @fqname string. The pointers returned point
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* into the @fqname string.
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*/
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char *aa_split_fqname(char *fqname, char **ns_name)
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{
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char *name = strim(fqname);
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*ns_name = NULL;
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if (name[0] == ':') {
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char *split = strchr(&name[1], ':');
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*ns_name = skip_spaces(&name[1]);
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if (split) {
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/* overwrite ':' with \0 */
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*split++ = 0;
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if (strncmp(split, "//", 2) == 0)
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split += 2;
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name = skip_spaces(split);
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} else
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/* a ns name without a following profile is allowed */
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name = NULL;
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}
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if (name && *name == 0)
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name = NULL;
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return name;
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}
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/**
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* skipn_spaces - Removes leading whitespace from @str.
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* @str: The string to be stripped.
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*
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* Returns a pointer to the first non-whitespace character in @str.
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* if all whitespace will return NULL
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*/
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const char *skipn_spaces(const char *str, size_t n)
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{
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for (; n && isspace(*str); --n)
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++str;
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if (n)
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return (char *)str;
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return NULL;
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}
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const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
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size_t *ns_len)
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{
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const char *end = fqname + n;
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const char *name = skipn_spaces(fqname, n);
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*ns_name = NULL;
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*ns_len = 0;
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if (!name)
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return NULL;
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if (name[0] == ':') {
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char *split = strnchr(&name[1], end - &name[1], ':');
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*ns_name = skipn_spaces(&name[1], end - &name[1]);
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if (!*ns_name)
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return NULL;
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if (split) {
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*ns_len = split - *ns_name;
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if (*ns_len == 0)
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*ns_name = NULL;
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split++;
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if (end - split > 1 && strncmp(split, "//", 2) == 0)
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split += 2;
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name = skipn_spaces(split, end - split);
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} else {
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/* a ns name without a following profile is allowed */
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name = NULL;
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*ns_len = end - *ns_name;
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}
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}
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if (name && *name == 0)
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name = NULL;
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return name;
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}
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/**
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* aa_info_message - log a none profile related status message
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* @str: message to log
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*/
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void aa_info_message(const char *str)
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{
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if (audit_enabled) {
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DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, NULL);
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aad(&sa)->info = str;
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aa_audit_msg(AUDIT_APPARMOR_STATUS, &sa, NULL);
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}
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printk(KERN_INFO "AppArmor: %s\n", str);
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}
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__counted char *aa_str_alloc(int size, gfp_t gfp)
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{
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struct counted_str *str;
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str = kmalloc(sizeof(struct counted_str) + size, gfp);
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if (!str)
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return NULL;
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kref_init(&str->count);
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return str->name;
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}
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void aa_str_kref(struct kref *kref)
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{
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kfree(container_of(kref, struct counted_str, count));
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}
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const char aa_file_perm_chrs[] = "xwracd km l ";
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const char *aa_file_perm_names[] = {
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"exec",
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"write",
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"read",
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"append",
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"create",
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"delete",
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"open",
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"rename",
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"setattr",
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"getattr",
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"setcred",
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"getcred",
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"chmod",
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"chown",
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"chgrp",
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"lock",
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"mmap",
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"mprot",
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"link",
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"snapshot",
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"unknown",
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"unknown",
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"unknown",
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"unknown",
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"unknown",
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"unknown",
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"unknown",
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"unknown",
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"stack",
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"change_onexec",
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"change_profile",
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"change_hat",
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};
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/**
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* aa_perm_mask_to_str - convert a perm mask to its short string
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* @str: character buffer to store string in (at least 10 characters)
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* @str_size: size of the @str buffer
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* @chrs: NUL-terminated character buffer of permission characters
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* @mask: permission mask to convert
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*/
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void aa_perm_mask_to_str(char *str, size_t str_size, const char *chrs, u32 mask)
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{
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unsigned int i, perm = 1;
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size_t num_chrs = strlen(chrs);
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for (i = 0; i < num_chrs; perm <<= 1, i++) {
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if (mask & perm) {
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/* Ensure that one byte is left for NUL-termination */
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if (WARN_ON_ONCE(str_size <= 1))
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break;
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*str++ = chrs[i];
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str_size--;
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}
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}
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*str = '\0';
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}
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void aa_audit_perm_names(struct audit_buffer *ab, const char * const *names,
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u32 mask)
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{
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const char *fmt = "%s";
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unsigned int i, perm = 1;
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bool prev = false;
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for (i = 0; i < 32; perm <<= 1, i++) {
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if (mask & perm) {
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audit_log_format(ab, fmt, names[i]);
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if (!prev) {
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prev = true;
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fmt = " %s";
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}
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}
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}
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}
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void aa_audit_perm_mask(struct audit_buffer *ab, u32 mask, const char *chrs,
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u32 chrsmask, const char * const *names, u32 namesmask)
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{
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char str[33];
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audit_log_format(ab, "\"");
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if ((mask & chrsmask) && chrs) {
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aa_perm_mask_to_str(str, sizeof(str), chrs, mask & chrsmask);
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mask &= ~chrsmask;
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audit_log_format(ab, "%s", str);
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if (mask & namesmask)
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audit_log_format(ab, " ");
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}
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if ((mask & namesmask) && names)
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aa_audit_perm_names(ab, names, mask & namesmask);
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audit_log_format(ab, "\"");
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}
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/**
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* aa_audit_perms_cb - generic callback fn for auditing perms
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* @ab: audit buffer (NOT NULL)
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* @va: audit struct to audit values of (NOT NULL)
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*/
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static void aa_audit_perms_cb(struct audit_buffer *ab, void *va)
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{
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struct common_audit_data *sa = va;
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if (aad(sa)->request) {
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audit_log_format(ab, " requested_mask=");
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aa_audit_perm_mask(ab, aad(sa)->request, aa_file_perm_chrs,
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PERMS_CHRS_MASK, aa_file_perm_names,
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PERMS_NAMES_MASK);
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}
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if (aad(sa)->denied) {
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audit_log_format(ab, "denied_mask=");
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aa_audit_perm_mask(ab, aad(sa)->denied, aa_file_perm_chrs,
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PERMS_CHRS_MASK, aa_file_perm_names,
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PERMS_NAMES_MASK);
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}
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audit_log_format(ab, " peer=");
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aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
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FLAGS_NONE, GFP_ATOMIC);
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}
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/**
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* aa_apply_modes_to_perms - apply namespace and profile flags to perms
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* @profile: that perms where computed from
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* @perms: perms to apply mode modifiers to
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*
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* TODO: split into profile and ns based flags for when accumulating perms
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*/
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void aa_apply_modes_to_perms(struct aa_profile *profile, struct aa_perms *perms)
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{
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switch (AUDIT_MODE(profile)) {
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case AUDIT_ALL:
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perms->audit = ALL_PERMS_MASK;
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/* fall through */
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case AUDIT_NOQUIET:
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perms->quiet = 0;
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break;
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case AUDIT_QUIET:
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perms->audit = 0;
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/* fall through */
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case AUDIT_QUIET_DENIED:
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perms->quiet = ALL_PERMS_MASK;
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break;
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}
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if (KILL_MODE(profile))
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perms->kill = ALL_PERMS_MASK;
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else if (COMPLAIN_MODE(profile))
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perms->complain = ALL_PERMS_MASK;
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/*
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* TODO:
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* else if (PROMPT_MODE(profile))
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* perms->prompt = ALL_PERMS_MASK;
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*/
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}
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static u32 map_other(u32 x)
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{
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return ((x & 0x3) << 8) | /* SETATTR/GETATTR */
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((x & 0x1c) << 18) | /* ACCEPT/BIND/LISTEN */
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((x & 0x60) << 19); /* SETOPT/GETOPT */
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}
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void aa_compute_perms(struct aa_dfa *dfa, unsigned int state,
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struct aa_perms *perms)
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{
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*perms = (struct aa_perms) {
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.allow = dfa_user_allow(dfa, state),
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.audit = dfa_user_audit(dfa, state),
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.quiet = dfa_user_quiet(dfa, state),
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};
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/* for v5 perm mapping in the policydb, the other set is used
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* to extend the general perm set
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*/
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perms->allow |= map_other(dfa_other_allow(dfa, state));
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perms->audit |= map_other(dfa_other_audit(dfa, state));
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perms->quiet |= map_other(dfa_other_quiet(dfa, state));
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// perms->xindex = dfa_user_xindex(dfa, state);
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}
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/**
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* aa_perms_accum_raw - accumulate perms with out masking off overlapping perms
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* @accum - perms struct to accumulate into
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* @addend - perms struct to add to @accum
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*/
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void aa_perms_accum_raw(struct aa_perms *accum, struct aa_perms *addend)
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{
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accum->deny |= addend->deny;
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accum->allow &= addend->allow & ~addend->deny;
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accum->audit |= addend->audit & addend->allow;
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accum->quiet &= addend->quiet & ~addend->allow;
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accum->kill |= addend->kill & ~addend->allow;
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accum->stop |= addend->stop & ~addend->allow;
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accum->complain |= addend->complain & ~addend->allow & ~addend->deny;
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accum->cond |= addend->cond & ~addend->allow & ~addend->deny;
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accum->hide &= addend->hide & ~addend->allow;
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accum->prompt |= addend->prompt & ~addend->allow & ~addend->deny;
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}
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/**
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* aa_perms_accum - accumulate perms, masking off overlapping perms
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* @accum - perms struct to accumulate into
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* @addend - perms struct to add to @accum
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*/
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void aa_perms_accum(struct aa_perms *accum, struct aa_perms *addend)
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{
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accum->deny |= addend->deny;
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accum->allow &= addend->allow & ~accum->deny;
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accum->audit |= addend->audit & accum->allow;
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accum->quiet &= addend->quiet & ~accum->allow;
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accum->kill |= addend->kill & ~accum->allow;
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accum->stop |= addend->stop & ~accum->allow;
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accum->complain |= addend->complain & ~accum->allow & ~accum->deny;
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accum->cond |= addend->cond & ~accum->allow & ~accum->deny;
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accum->hide &= addend->hide & ~accum->allow;
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accum->prompt |= addend->prompt & ~accum->allow & ~accum->deny;
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}
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void aa_profile_match_label(struct aa_profile *profile, struct aa_label *label,
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int type, u32 request, struct aa_perms *perms)
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{
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/* TODO: doesn't yet handle extended types */
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unsigned int state;
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state = aa_dfa_next(profile->policy.dfa,
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profile->policy.start[AA_CLASS_LABEL],
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type);
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aa_label_match(profile, label, state, false, request, perms);
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}
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/* currently unused */
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int aa_profile_label_perm(struct aa_profile *profile, struct aa_profile *target,
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u32 request, int type, u32 *deny,
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struct common_audit_data *sa)
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{
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struct aa_perms perms;
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aad(sa)->label = &profile->label;
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aad(sa)->peer = &target->label;
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aad(sa)->request = request;
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aa_profile_match_label(profile, &target->label, type, request, &perms);
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aa_apply_modes_to_perms(profile, &perms);
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*deny |= request & perms.deny;
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return aa_check_perms(profile, &perms, request, sa, aa_audit_perms_cb);
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}
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/**
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* aa_check_perms - do audit mode selection based on perms set
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* @profile: profile being checked
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* @perms: perms computed for the request
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* @request: requested perms
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* @deny: Returns: explicit deny set
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* @sa: initialized audit structure (MAY BE NULL if not auditing)
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* @cb: callback fn for type specific fields (MAY BE NULL)
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*
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* Returns: 0 if permission else error code
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*
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* Note: profile audit modes need to be set before calling by setting the
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* perm masks appropriately.
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*
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* If not auditing then complain mode is not enabled and the
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* error code will indicate whether there was an explicit deny
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* with a positive value.
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*/
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int aa_check_perms(struct aa_profile *profile, struct aa_perms *perms,
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u32 request, struct common_audit_data *sa,
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void (*cb)(struct audit_buffer *, void *))
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{
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int type, error;
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u32 denied = request & (~perms->allow | perms->deny);
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if (likely(!denied)) {
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/* mask off perms that are not being force audited */
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request &= perms->audit;
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if (!request || !sa)
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return 0;
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type = AUDIT_APPARMOR_AUDIT;
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error = 0;
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} else {
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error = -EACCES;
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if (denied & perms->kill)
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type = AUDIT_APPARMOR_KILL;
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else if (denied == (denied & perms->complain))
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type = AUDIT_APPARMOR_ALLOWED;
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else
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type = AUDIT_APPARMOR_DENIED;
|
|
|
|
if (denied == (denied & perms->hide))
|
|
error = -ENOENT;
|
|
|
|
denied &= ~perms->quiet;
|
|
if (!sa || !denied)
|
|
return error;
|
|
}
|
|
|
|
if (sa) {
|
|
aad(sa)->label = &profile->label;
|
|
aad(sa)->request = request;
|
|
aad(sa)->denied = denied;
|
|
aad(sa)->error = error;
|
|
aa_audit_msg(type, sa, cb);
|
|
}
|
|
|
|
if (type == AUDIT_APPARMOR_ALLOWED)
|
|
error = 0;
|
|
|
|
return error;
|
|
}
|
|
|
|
|
|
/**
|
|
* aa_policy_init - initialize a policy structure
|
|
* @policy: policy to initialize (NOT NULL)
|
|
* @prefix: prefix name if any is required. (MAYBE NULL)
|
|
* @name: name of the policy, init will make a copy of it (NOT NULL)
|
|
* @gfp: allocation mode
|
|
*
|
|
* Note: this fn creates a copy of strings passed in
|
|
*
|
|
* Returns: true if policy init successful
|
|
*/
|
|
bool aa_policy_init(struct aa_policy *policy, const char *prefix,
|
|
const char *name, gfp_t gfp)
|
|
{
|
|
char *hname;
|
|
|
|
/* freed by policy_free */
|
|
if (prefix) {
|
|
hname = aa_str_alloc(strlen(prefix) + strlen(name) + 3, gfp);
|
|
if (hname)
|
|
sprintf(hname, "%s//%s", prefix, name);
|
|
} else {
|
|
hname = aa_str_alloc(strlen(name) + 1, gfp);
|
|
if (hname)
|
|
strcpy(hname, name);
|
|
}
|
|
if (!hname)
|
|
return false;
|
|
policy->hname = hname;
|
|
/* base.name is a substring of fqname */
|
|
policy->name = basename(policy->hname);
|
|
INIT_LIST_HEAD(&policy->list);
|
|
INIT_LIST_HEAD(&policy->profiles);
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* aa_policy_destroy - free the elements referenced by @policy
|
|
* @policy: policy that is to have its elements freed (NOT NULL)
|
|
*/
|
|
void aa_policy_destroy(struct aa_policy *policy)
|
|
{
|
|
AA_BUG(on_list_rcu(&policy->profiles));
|
|
AA_BUG(on_list_rcu(&policy->list));
|
|
|
|
/* don't free name as its a subset of hname */
|
|
aa_put_str(policy->hname);
|
|
}
|