2 * AppArmor security module
4 * This file contains AppArmor policy attachment and domain transitions
6 * Copyright (C) 2002-2008 Novell/SUSE
7 * Copyright 2009-2010 Canonical Ltd.
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation, version 2 of the
15 #include <linux/errno.h>
16 #include <linux/fdtable.h>
17 #include <linux/file.h>
18 #include <linux/mount.h>
19 #include <linux/syscalls.h>
20 #include <linux/tracehook.h>
21 #include <linux/personality.h>
23 #include "include/audit.h"
24 #include "include/apparmorfs.h"
25 #include "include/context.h"
26 #include "include/domain.h"
27 #include "include/file.h"
28 #include "include/ipc.h"
29 #include "include/match.h"
30 #include "include/path.h"
31 #include "include/policy.h"
34 * aa_free_domain_entries - free entries in a domain table
35 * @domain: the domain table to free (MAYBE NULL)
37 void aa_free_domain_entries(struct aa_domain
*domain
)
44 for (i
= 0; i
< domain
->size
; i
++)
45 kzfree(domain
->table
[i
]);
46 kzfree(domain
->table
);
52 * may_change_ptraced_domain - check if can change profile on ptraced task
53 * @to_profile: profile to change to (NOT NULL)
55 * Check if current is ptraced and if so if the tracing task is allowed
56 * to trace the new domain
58 * Returns: %0 or error if change not allowed
60 static int may_change_ptraced_domain(struct aa_profile
*to_profile
)
62 struct task_struct
*tracer
;
63 struct aa_profile
*tracerp
= NULL
;
67 tracer
= ptrace_parent(current
);
70 tracerp
= aa_get_task_profile(tracer
);
73 if (!tracer
|| unconfined(tracerp
))
76 error
= aa_may_ptrace(tracerp
, to_profile
, PTRACE_MODE_ATTACH
);
80 aa_put_profile(tracerp
);
86 * change_profile_perms - find permissions for change_profile
87 * @profile: the current profile (NOT NULL)
88 * @ns: the namespace being switched to (NOT NULL)
89 * @name: the name of the profile to change to (NOT NULL)
90 * @request: requested perms
91 * @start: state to start matching in
93 * Returns: permission set
95 static struct file_perms
change_profile_perms(struct aa_profile
*profile
,
96 struct aa_namespace
*ns
,
97 const char *name
, u32 request
,
100 struct file_perms perms
;
101 struct path_cond cond
= { };
104 if (unconfined(profile
)) {
105 perms
.allow
= AA_MAY_CHANGE_PROFILE
| AA_MAY_ONEXEC
;
106 perms
.audit
= perms
.quiet
= perms
.kill
= 0;
108 } else if (!profile
->file
.dfa
) {
110 } else if ((ns
== profile
->ns
)) {
111 /* try matching against rules with out namespace prepended */
112 aa_str_perms(profile
->file
.dfa
, start
, name
, &cond
, &perms
);
113 if (COMBINED_PERM_MASK(perms
) & request
)
117 /* try matching with namespace name and then profile */
118 state
= aa_dfa_match(profile
->file
.dfa
, start
, ns
->base
.name
);
119 state
= aa_dfa_match_len(profile
->file
.dfa
, state
, ":", 1);
120 aa_str_perms(profile
->file
.dfa
, state
, name
, &cond
, &perms
);
126 * __attach_match_ - find an attachment match
127 * @name - to match against (NOT NULL)
128 * @head - profile list to walk (NOT NULL)
130 * Do a linear search on the profiles in the list. There is a matching
131 * preference where an exact match is preferred over a name which uses
132 * expressions to match, and matching expressions with the greatest
133 * xmatch_len are preferred.
135 * Requires: @head not be shared or have appropriate locks held
137 * Returns: profile or NULL if no match found
139 static struct aa_profile
*__attach_match(const char *name
,
140 struct list_head
*head
)
143 struct aa_profile
*profile
, *candidate
= NULL
;
145 list_for_each_entry_rcu(profile
, head
, base
.list
) {
146 if (profile
->flags
& PFLAG_NULL
)
148 if (profile
->xmatch
&& profile
->xmatch_len
> len
) {
149 unsigned int state
= aa_dfa_match(profile
->xmatch
,
151 u32 perm
= dfa_user_allow(profile
->xmatch
, state
);
152 /* any accepting state means a valid match. */
153 if (perm
& MAY_EXEC
) {
155 len
= profile
->xmatch_len
;
157 } else if (!strcmp(profile
->base
.name
, name
))
158 /* exact non-re match, no more searching required */
166 * find_attach - do attachment search for unconfined processes
167 * @ns: the current namespace (NOT NULL)
168 * @list: list to search (NOT NULL)
169 * @name: the executable name to match against (NOT NULL)
171 * Returns: profile or NULL if no match found
173 static struct aa_profile
*find_attach(struct aa_namespace
*ns
,
174 struct list_head
*list
, const char *name
)
176 struct aa_profile
*profile
;
179 profile
= aa_get_profile(__attach_match(name
, list
));
186 * separate_fqname - separate the namespace and profile names
187 * @fqname: the fqname name to split (NOT NULL)
188 * @ns_name: the namespace name if it exists (NOT NULL)
190 * This is the xtable equivalent routine of aa_split_fqname. It finds the
191 * split in an xtable fqname which contains an embedded \0 instead of a :
192 * if a namespace is specified. This is done so the xtable is constant and
193 * isn't re-split on every lookup.
195 * Either the profile or namespace name may be optional but if the namespace
196 * is specified the profile name termination must be present. This results
197 * in the following possible encodings:
199 * :ns_name\0profile_name\0
202 * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table
204 * Returns: profile name if it is specified else NULL
206 static const char *separate_fqname(const char *fqname
, const char **ns_name
)
210 if (fqname
[0] == ':') {
211 /* In this case there is guaranteed to be two \0 terminators
212 * in the string. They are verified at load time by
213 * by unpack_trans_table
215 *ns_name
= fqname
+ 1; /* skip : */
216 name
= *ns_name
+ strlen(*ns_name
) + 1;
227 static const char *next_name(int xtype
, const char *name
)
233 * x_table_lookup - lookup an x transition name via transition table
234 * @profile: current profile (NOT NULL)
235 * @xindex: index into x transition table
237 * Returns: refcounted profile, or NULL on failure (MAYBE NULL)
239 static struct aa_profile
*x_table_lookup(struct aa_profile
*profile
, u32 xindex
)
241 struct aa_profile
*new_profile
= NULL
;
242 struct aa_namespace
*ns
= profile
->ns
;
243 u32 xtype
= xindex
& AA_X_TYPE_MASK
;
244 int index
= xindex
& AA_X_INDEX_MASK
;
247 /* index is guaranteed to be in range, validated at load time */
248 for (name
= profile
->file
.trans
.table
[index
]; !new_profile
&& name
;
249 name
= next_name(xtype
, name
)) {
250 struct aa_namespace
*new_ns
;
251 const char *xname
= NULL
;
254 if (xindex
& AA_X_CHILD
) {
255 /* release by caller */
256 new_profile
= aa_find_child(profile
, name
);
258 } else if (*name
== ':') {
259 /* switching namespace */
261 xname
= name
= separate_fqname(name
, &ns_name
);
263 /* no name so use profile name */
264 xname
= profile
->base
.hname
;
265 if (*ns_name
== '@') {
266 /* TODO: variable support */
270 new_ns
= aa_find_namespace(ns
, ns_name
);
273 } else if (*name
== '@') {
274 /* TODO: variable support */
277 /* basic namespace lookup */
281 /* released by caller */
282 new_profile
= aa_lookup_profile(new_ns
? new_ns
: ns
, xname
);
283 aa_put_namespace(new_ns
);
286 /* released by caller */
291 * x_to_profile - get target profile for a given xindex
292 * @profile: current profile (NOT NULL)
293 * @name: name to lookup (NOT NULL)
294 * @xindex: index into x transition table
296 * find profile for a transition index
298 * Returns: refcounted profile or NULL if not found available
300 static struct aa_profile
*x_to_profile(struct aa_profile
*profile
,
301 const char *name
, u32 xindex
)
303 struct aa_profile
*new_profile
= NULL
;
304 struct aa_namespace
*ns
= profile
->ns
;
305 u32 xtype
= xindex
& AA_X_TYPE_MASK
;
309 /* fail exec unless ix || ux fallback - handled by caller */
312 if (xindex
& AA_X_CHILD
)
313 /* released by caller */
314 new_profile
= find_attach(ns
, &profile
->base
.profiles
,
317 /* released by caller */
318 new_profile
= find_attach(ns
, &ns
->base
.profiles
,
322 /* released by caller */
323 new_profile
= x_table_lookup(profile
, xindex
);
327 /* released by caller */
332 * apparmor_bprm_set_creds - set the new creds on the bprm struct
333 * @bprm: binprm for the exec (NOT NULL)
335 * Returns: %0 or error on failure
337 int apparmor_bprm_set_creds(struct linux_binprm
*bprm
)
339 struct aa_task_cxt
*cxt
;
340 struct aa_profile
*profile
, *new_profile
= NULL
;
341 struct aa_namespace
*ns
;
344 struct file_perms perms
= {};
345 struct path_cond cond
= {
346 file_inode(bprm
->file
)->i_uid
,
347 file_inode(bprm
->file
)->i_mode
349 const char *name
= NULL
, *info
= NULL
;
352 if (bprm
->cred_prepared
)
355 cxt
= cred_cxt(bprm
->cred
);
358 profile
= aa_get_newest_profile(cxt
->profile
);
360 * get the namespace from the replacement profile as replacement
361 * can change the namespace
364 state
= profile
->file
.start
;
366 /* buffer freed below, name is pointer into buffer */
367 error
= aa_path_name(&bprm
->file
->f_path
, profile
->path_flags
, &buffer
,
370 if (unconfined(profile
) ||
371 (profile
->flags
& PFLAG_IX_ON_NAME_ERROR
))
373 name
= bprm
->filename
;
377 /* Test for onexec first as onexec directives override other
380 if (unconfined(profile
)) {
381 /* unconfined task */
383 /* change_profile on exec already been granted */
384 new_profile
= aa_get_profile(cxt
->onexec
);
386 new_profile
= find_attach(ns
, &ns
->base
.profiles
, name
);
390 * NOTE: Domain transitions from unconfined are allowed
391 * even when no_new_privs is set because this aways results
392 * in a further reduction of permissions.
397 /* find exec permissions for name */
398 state
= aa_str_perms(profile
->file
.dfa
, state
, name
, &cond
, &perms
);
400 struct file_perms cp
;
401 info
= "change_profile onexec";
402 new_profile
= aa_get_newest_profile(cxt
->onexec
);
403 if (!(perms
.allow
& AA_MAY_ONEXEC
))
406 /* test if this exec can be paired with change_profile onexec.
407 * onexec permission is linked to exec with a standard pairing
408 * exec\0change_profile
410 state
= aa_dfa_null_transition(profile
->file
.dfa
, state
);
411 cp
= change_profile_perms(profile
, cxt
->onexec
->ns
,
412 cxt
->onexec
->base
.name
,
413 AA_MAY_ONEXEC
, state
);
415 if (!(cp
.allow
& AA_MAY_ONEXEC
))
420 if (perms
.allow
& MAY_EXEC
) {
421 /* exec permission determine how to transition */
422 new_profile
= x_to_profile(profile
, name
, perms
.xindex
);
424 if (perms
.xindex
& AA_X_INHERIT
) {
425 /* (p|c|n)ix - don't change profile but do
426 * use the newest version, which was picked
427 * up above when getting profile
429 info
= "ix fallback";
430 new_profile
= aa_get_profile(profile
);
432 } else if (perms
.xindex
& AA_X_UNCONFINED
) {
433 new_profile
= aa_get_newest_profile(ns
->unconfined
);
434 info
= "ux fallback";
437 info
= "profile not found";
438 /* remove MAY_EXEC to audit as failure */
439 perms
.allow
&= ~MAY_EXEC
;
442 } else if (COMPLAIN_MODE(profile
)) {
443 /* no exec permission - are we in learning mode */
444 new_profile
= aa_new_null_profile(profile
, 0);
447 info
= "could not create null profile";
450 perms
.xindex
|= AA_X_UNSAFE
;
456 * Policy has specified a domain transition, if no_new_privs then
459 if (bprm
->unsafe
& LSM_UNSAFE_NO_NEW_PRIVS
) {
467 if (bprm
->unsafe
& LSM_UNSAFE_SHARE
) {
468 /* FIXME: currently don't mediate shared state */
472 if (bprm
->unsafe
& (LSM_UNSAFE_PTRACE
| LSM_UNSAFE_PTRACE_CAP
)) {
473 error
= may_change_ptraced_domain(new_profile
);
478 /* Determine if secure exec is needed.
479 * Can be at this point for the following reasons:
480 * 1. unconfined switching to confined
481 * 2. confined switching to different confinement
482 * 3. confined switching to unconfined
484 * Cases 2 and 3 are marked as requiring secure exec
485 * (unless policy specified "unsafe exec")
487 * bprm->unsafe is used to cache the AA_X_UNSAFE permission
488 * to avoid having to recompute in secureexec
490 if (!(perms
.xindex
& AA_X_UNSAFE
)) {
491 AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
492 name
, new_profile
->base
.hname
);
493 bprm
->unsafe
|= AA_SECURE_X_NEEDED
;
496 /* when transitioning profiles clear unsafe personality bits */
497 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
500 aa_put_profile(cxt
->profile
);
501 /* transfer new profile reference will be released when cxt is freed */
502 cxt
->profile
= new_profile
;
505 /* clear out all temporary/transitional state from the context */
506 aa_clear_task_cxt_trans(cxt
);
509 error
= aa_audit_file(profile
, &perms
, GFP_KERNEL
, OP_EXEC
, MAY_EXEC
,
511 new_profile
? new_profile
->base
.hname
: NULL
,
512 cond
.uid
, info
, error
);
515 aa_put_profile(new_profile
);
516 aa_put_profile(profile
);
523 * apparmor_bprm_secureexec - determine if secureexec is needed
524 * @bprm: binprm for exec (NOT NULL)
526 * Returns: %1 if secureexec is needed else %0
528 int apparmor_bprm_secureexec(struct linux_binprm
*bprm
)
530 /* the decision to use secure exec is computed in set_creds
531 * and stored in bprm->unsafe.
533 if (bprm
->unsafe
& AA_SECURE_X_NEEDED
)
540 * apparmor_bprm_committing_creds - do task cleanup on committing new creds
541 * @bprm: binprm for the exec (NOT NULL)
543 void apparmor_bprm_committing_creds(struct linux_binprm
*bprm
)
545 struct aa_profile
*profile
= __aa_current_profile();
546 struct aa_task_cxt
*new_cxt
= cred_cxt(bprm
->cred
);
548 /* bail out if unconfined or not changing profile */
549 if ((new_cxt
->profile
== profile
) ||
550 (unconfined(new_cxt
->profile
)))
553 current
->pdeath_signal
= 0;
555 /* reset soft limits and set hard limits for the new profile */
556 __aa_transition_rlimits(profile
, new_cxt
->profile
);
560 * apparmor_bprm_commited_cred - do cleanup after new creds committed
561 * @bprm: binprm for the exec (NOT NULL)
563 void apparmor_bprm_committed_creds(struct linux_binprm
*bprm
)
565 /* TODO: cleanup signals - ipc mediation */
570 * Functions for self directed profile change
574 * new_compound_name - create an hname with @n2 appended to @n1
575 * @n1: base of hname (NOT NULL)
576 * @n2: name to append (NOT NULL)
578 * Returns: new name or NULL on error
580 static char *new_compound_name(const char *n1
, const char *n2
)
582 char *name
= kmalloc(strlen(n1
) + strlen(n2
) + 3, GFP_KERNEL
);
584 sprintf(name
, "%s//%s", n1
, n2
);
589 * aa_change_hat - change hat to/from subprofile
590 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
591 * @count: number of hat names in @hats
592 * @token: magic value to validate the hat change
593 * @permtest: true if this is just a permission test
595 * Change to the first profile specified in @hats that exists, and store
596 * the @hat_magic in the current task context. If the count == 0 and the
597 * @token matches that stored in the current task context, return to the
600 * Returns %0 on success, error otherwise.
602 int aa_change_hat(const char *hats
[], int count
, u64 token
, bool permtest
)
604 const struct cred
*cred
;
605 struct aa_task_cxt
*cxt
;
606 struct aa_profile
*profile
, *previous_profile
, *hat
= NULL
;
609 struct file_perms perms
= {};
610 const char *target
= NULL
, *info
= NULL
;
614 * Fail explicitly requested domain transitions if no_new_privs.
615 * There is no exception for unconfined as change_hat is not
618 if (task_no_new_privs(current
))
622 cred
= get_current_cred();
623 cxt
= cred_cxt(cred
);
624 profile
= aa_get_newest_profile(aa_cred_profile(cred
));
625 previous_profile
= aa_get_newest_profile(cxt
->previous
);
627 if (unconfined(profile
)) {
634 /* attempting to change into a new hat or switch to a sibling */
635 struct aa_profile
*root
;
636 if (PROFILE_IS_HAT(profile
))
637 root
= aa_get_profile_rcu(&profile
->parent
);
639 root
= aa_get_profile(profile
);
641 /* find first matching hat */
642 for (i
= 0; i
< count
&& !hat
; i
++)
644 hat
= aa_find_child(root
, hats
[i
]);
646 if (!COMPLAIN_MODE(root
) || permtest
) {
647 if (list_empty(&root
->base
.profiles
))
651 aa_put_profile(root
);
656 * In complain mode and failed to match any hats.
657 * Audit the failure is based off of the first hat
658 * supplied. This is done due how userspace
659 * interacts with change_hat.
661 * TODO: Add logging of all failed hats
665 name
= new_compound_name(root
->base
.hname
, hats
[0]);
666 aa_put_profile(root
);
669 hat
= aa_new_null_profile(profile
, 1);
671 info
= "failed null profile create";
676 aa_put_profile(root
);
677 target
= hat
->base
.hname
;
678 if (!PROFILE_IS_HAT(hat
)) {
679 info
= "target not hat";
685 error
= may_change_ptraced_domain(hat
);
693 error
= aa_set_current_hat(hat
, token
);
694 if (error
== -EACCES
)
695 /* kill task in case of brute force attacks */
696 perms
.kill
= AA_MAY_CHANGEHAT
;
697 else if (name
&& !error
)
698 /* reset error for learning of new hats */
701 } else if (previous_profile
) {
702 /* Return to saved profile. Kill task if restore fails
703 * to avoid brute force attacks
705 target
= previous_profile
->base
.hname
;
706 error
= aa_restore_previous_profile(token
);
707 perms
.kill
= AA_MAY_CHANGEHAT
;
709 /* ignore restores when there is no saved profile */
714 error
= aa_audit_file(profile
, &perms
, GFP_KERNEL
,
715 OP_CHANGE_HAT
, AA_MAY_CHANGEHAT
, NULL
,
716 target
, GLOBAL_ROOT_UID
, info
, error
);
721 aa_put_profile(profile
);
722 aa_put_profile(previous_profile
);
729 * aa_change_profile - perform a one-way profile transition
730 * @ns_name: name of the profile namespace to change to (MAYBE NULL)
731 * @hname: name of profile to change to (MAYBE NULL)
732 * @onexec: whether this transition is to take place immediately or at exec
733 * @permtest: true if this is just a permission test
735 * Change to new profile @name. Unlike with hats, there is no way
736 * to change back. If @name isn't specified the current profile name is
738 * If @onexec then the transition is delayed until
741 * Returns %0 on success, error otherwise.
743 int aa_change_profile(const char *ns_name
, const char *hname
, bool onexec
,
746 const struct cred
*cred
;
747 struct aa_profile
*profile
, *target
= NULL
;
748 struct aa_namespace
*ns
= NULL
;
749 struct file_perms perms
= {};
750 const char *name
= NULL
, *info
= NULL
;
754 if (!hname
&& !ns_name
)
758 request
= AA_MAY_ONEXEC
;
759 op
= OP_CHANGE_ONEXEC
;
761 request
= AA_MAY_CHANGE_PROFILE
;
762 op
= OP_CHANGE_PROFILE
;
765 cred
= get_current_cred();
766 profile
= aa_cred_profile(cred
);
769 * Fail explicitly requested domain transitions if no_new_privs
770 * and not unconfined.
771 * Domain transitions from unconfined are allowed even when
772 * no_new_privs is set because this aways results in a reduction
775 if (task_no_new_privs(current
) && !unconfined(profile
)) {
782 ns
= aa_find_namespace(profile
->ns
, ns_name
);
784 /* we don't create new namespace in complain mode */
786 info
= "namespace not found";
792 ns
= aa_get_namespace(profile
->ns
);
794 /* if the name was not specified, use the name of the current profile */
796 if (unconfined(profile
))
797 hname
= ns
->unconfined
->base
.hname
;
799 hname
= profile
->base
.hname
;
802 perms
= change_profile_perms(profile
, ns
, hname
, request
,
803 profile
->file
.start
);
804 if (!(perms
.allow
& request
)) {
810 target
= aa_lookup_profile(ns
, hname
);
812 info
= "profile not found";
814 if (permtest
|| !COMPLAIN_MODE(profile
))
817 target
= aa_new_null_profile(profile
, 0);
819 info
= "failed null profile create";
825 /* check if tracing task is allowed to trace target domain */
826 error
= may_change_ptraced_domain(target
);
828 info
= "ptrace prevents transition";
836 error
= aa_set_current_onexec(target
);
838 error
= aa_replace_current_profile(target
);
842 error
= aa_audit_file(profile
, &perms
, GFP_KERNEL
, op
, request
,
843 name
, hname
, GLOBAL_ROOT_UID
, info
, error
);
845 aa_put_namespace(ns
);
846 aa_put_profile(target
);