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 * @task: task we want to change profile of (NOT NULL)
54 * @to_profile: profile to change to (NOT NULL)
56 * Check if the task is ptraced and if so if the tracing task is allowed
57 * to trace the new domain
59 * Returns: %0 or error if change not allowed
61 static int may_change_ptraced_domain(struct task_struct
*task
,
62 struct aa_profile
*to_profile
)
64 struct task_struct
*tracer
;
65 struct aa_profile
*tracerp
= NULL
;
69 tracer
= ptrace_parent(task
);
72 tracerp
= aa_get_task_profile(tracer
);
75 if (!tracer
|| unconfined(tracerp
))
78 error
= aa_may_ptrace(tracer
, tracerp
, to_profile
, PTRACE_MODE_ATTACH
);
82 aa_put_profile(tracerp
);
88 * change_profile_perms - find permissions for change_profile
89 * @profile: the current profile (NOT NULL)
90 * @ns: the namespace being switched to (NOT NULL)
91 * @name: the name of the profile to change to (NOT NULL)
92 * @request: requested perms
93 * @start: state to start matching in
95 * Returns: permission set
97 static struct file_perms
change_profile_perms(struct aa_profile
*profile
,
98 struct aa_namespace
*ns
,
99 const char *name
, u32 request
,
102 struct file_perms perms
;
103 struct path_cond cond
= { };
106 if (unconfined(profile
)) {
107 perms
.allow
= AA_MAY_CHANGE_PROFILE
| AA_MAY_ONEXEC
;
108 perms
.audit
= perms
.quiet
= perms
.kill
= 0;
110 } else if (!profile
->file
.dfa
) {
112 } else if ((ns
== profile
->ns
)) {
113 /* try matching against rules with out namespace prepended */
114 aa_str_perms(profile
->file
.dfa
, start
, name
, &cond
, &perms
);
115 if (COMBINED_PERM_MASK(perms
) & request
)
119 /* try matching with namespace name and then profile */
120 state
= aa_dfa_match(profile
->file
.dfa
, start
, ns
->base
.name
);
121 state
= aa_dfa_match_len(profile
->file
.dfa
, state
, ":", 1);
122 aa_str_perms(profile
->file
.dfa
, state
, name
, &cond
, &perms
);
128 * __attach_match_ - find an attachment match
129 * @name - to match against (NOT NULL)
130 * @head - profile list to walk (NOT NULL)
132 * Do a linear search on the profiles in the list. There is a matching
133 * preference where an exact match is preferred over a name which uses
134 * expressions to match, and matching expressions with the greatest
135 * xmatch_len are preferred.
137 * Requires: @head not be shared or have appropriate locks held
139 * Returns: profile or NULL if no match found
141 static struct aa_profile
*__attach_match(const char *name
,
142 struct list_head
*head
)
145 struct aa_profile
*profile
, *candidate
= NULL
;
147 list_for_each_entry_rcu(profile
, head
, base
.list
) {
148 if (profile
->flags
& PFLAG_NULL
)
150 if (profile
->xmatch
&& profile
->xmatch_len
> len
) {
151 unsigned int state
= aa_dfa_match(profile
->xmatch
,
153 u32 perm
= dfa_user_allow(profile
->xmatch
, state
);
154 /* any accepting state means a valid match. */
155 if (perm
& MAY_EXEC
) {
157 len
= profile
->xmatch_len
;
159 } else if (!strcmp(profile
->base
.name
, name
))
160 /* exact non-re match, no more searching required */
168 * find_attach - do attachment search for unconfined processes
169 * @ns: the current namespace (NOT NULL)
170 * @list: list to search (NOT NULL)
171 * @name: the executable name to match against (NOT NULL)
173 * Returns: profile or NULL if no match found
175 static struct aa_profile
*find_attach(struct aa_namespace
*ns
,
176 struct list_head
*list
, const char *name
)
178 struct aa_profile
*profile
;
181 profile
= aa_get_profile(__attach_match(name
, list
));
188 * separate_fqname - separate the namespace and profile names
189 * @fqname: the fqname name to split (NOT NULL)
190 * @ns_name: the namespace name if it exists (NOT NULL)
192 * This is the xtable equivalent routine of aa_split_fqname. It finds the
193 * split in an xtable fqname which contains an embedded \0 instead of a :
194 * if a namespace is specified. This is done so the xtable is constant and
195 * isn't re-split on every lookup.
197 * Either the profile or namespace name may be optional but if the namespace
198 * is specified the profile name termination must be present. This results
199 * in the following possible encodings:
201 * :ns_name\0profile_name\0
204 * NOTE: the xtable fqname is pre-validated at load time in unpack_trans_table
206 * Returns: profile name if it is specified else NULL
208 static const char *separate_fqname(const char *fqname
, const char **ns_name
)
212 if (fqname
[0] == ':') {
213 /* In this case there is guaranteed to be two \0 terminators
214 * in the string. They are verified at load time by
215 * by unpack_trans_table
217 *ns_name
= fqname
+ 1; /* skip : */
218 name
= *ns_name
+ strlen(*ns_name
) + 1;
229 static const char *next_name(int xtype
, const char *name
)
235 * x_table_lookup - lookup an x transition name via transition table
236 * @profile: current profile (NOT NULL)
237 * @xindex: index into x transition table
239 * Returns: refcounted profile, or NULL on failure (MAYBE NULL)
241 static struct aa_profile
*x_table_lookup(struct aa_profile
*profile
, u32 xindex
)
243 struct aa_profile
*new_profile
= NULL
;
244 struct aa_namespace
*ns
= profile
->ns
;
245 u32 xtype
= xindex
& AA_X_TYPE_MASK
;
246 int index
= xindex
& AA_X_INDEX_MASK
;
249 /* index is guaranteed to be in range, validated at load time */
250 for (name
= profile
->file
.trans
.table
[index
]; !new_profile
&& name
;
251 name
= next_name(xtype
, name
)) {
252 struct aa_namespace
*new_ns
;
253 const char *xname
= NULL
;
256 if (xindex
& AA_X_CHILD
) {
257 /* release by caller */
258 new_profile
= aa_find_child(profile
, name
);
260 } else if (*name
== ':') {
261 /* switching namespace */
263 xname
= name
= separate_fqname(name
, &ns_name
);
265 /* no name so use profile name */
266 xname
= profile
->base
.hname
;
267 if (*ns_name
== '@') {
268 /* TODO: variable support */
272 new_ns
= aa_find_namespace(ns
, ns_name
);
275 } else if (*name
== '@') {
276 /* TODO: variable support */
279 /* basic namespace lookup */
283 /* released by caller */
284 new_profile
= aa_lookup_profile(new_ns
? new_ns
: ns
, xname
);
285 aa_put_namespace(new_ns
);
288 /* released by caller */
293 * x_to_profile - get target profile for a given xindex
294 * @profile: current profile (NOT NULL)
295 * @name: name to lookup (NOT NULL)
296 * @xindex: index into x transition table
298 * find profile for a transition index
300 * Returns: refcounted profile or NULL if not found available
302 static struct aa_profile
*x_to_profile(struct aa_profile
*profile
,
303 const char *name
, u32 xindex
)
305 struct aa_profile
*new_profile
= NULL
;
306 struct aa_namespace
*ns
= profile
->ns
;
307 u32 xtype
= xindex
& AA_X_TYPE_MASK
;
311 /* fail exec unless ix || ux fallback - handled by caller */
314 if (xindex
& AA_X_CHILD
)
315 /* released by caller */
316 new_profile
= find_attach(ns
, &profile
->base
.profiles
,
319 /* released by caller */
320 new_profile
= find_attach(ns
, &ns
->base
.profiles
,
324 /* released by caller */
325 new_profile
= x_table_lookup(profile
, xindex
);
329 /* released by caller */
334 * apparmor_bprm_set_creds - set the new creds on the bprm struct
335 * @bprm: binprm for the exec (NOT NULL)
337 * Returns: %0 or error on failure
339 int apparmor_bprm_set_creds(struct linux_binprm
*bprm
)
341 struct aa_task_cxt
*cxt
;
342 struct aa_profile
*profile
, *new_profile
= NULL
;
343 struct aa_namespace
*ns
;
346 struct file_perms perms
= {};
347 struct path_cond cond
= {
348 file_inode(bprm
->file
)->i_uid
,
349 file_inode(bprm
->file
)->i_mode
351 const char *name
= NULL
, *target
= NULL
, *info
= NULL
;
352 int error
= cap_bprm_set_creds(bprm
);
356 if (bprm
->cred_prepared
)
359 cxt
= cred_cxt(bprm
->cred
);
362 profile
= aa_get_newest_profile(cxt
->profile
);
364 * get the namespace from the replacement profile as replacement
365 * can change the namespace
368 state
= profile
->file
.start
;
370 /* buffer freed below, name is pointer into buffer */
371 error
= aa_path_name(&bprm
->file
->f_path
, profile
->path_flags
, &buffer
,
374 if (unconfined(profile
) ||
375 (profile
->flags
& PFLAG_IX_ON_NAME_ERROR
))
377 name
= bprm
->filename
;
381 /* Test for onexec first as onexec directives override other
384 if (unconfined(profile
)) {
385 /* unconfined task */
387 /* change_profile on exec already been granted */
388 new_profile
= aa_get_profile(cxt
->onexec
);
390 new_profile
= find_attach(ns
, &ns
->base
.profiles
, name
);
394 * NOTE: Domain transitions from unconfined are allowed
395 * even when no_new_privs is set because this aways results
396 * in a further reduction of permissions.
401 /* find exec permissions for name */
402 state
= aa_str_perms(profile
->file
.dfa
, state
, name
, &cond
, &perms
);
404 struct file_perms cp
;
405 info
= "change_profile onexec";
406 if (!(perms
.allow
& AA_MAY_ONEXEC
))
409 /* test if this exec can be paired with change_profile onexec.
410 * onexec permission is linked to exec with a standard pairing
411 * exec\0change_profile
413 state
= aa_dfa_null_transition(profile
->file
.dfa
, state
);
414 cp
= change_profile_perms(profile
, cxt
->onexec
->ns
,
415 cxt
->onexec
->base
.name
,
416 AA_MAY_ONEXEC
, state
);
418 if (!(cp
.allow
& AA_MAY_ONEXEC
))
420 new_profile
= aa_get_newest_profile(cxt
->onexec
);
424 if (perms
.allow
& MAY_EXEC
) {
425 /* exec permission determine how to transition */
426 new_profile
= x_to_profile(profile
, name
, perms
.xindex
);
428 if (perms
.xindex
& AA_X_INHERIT
) {
429 /* (p|c|n)ix - don't change profile but do
430 * use the newest version, which was picked
431 * up above when getting profile
433 info
= "ix fallback";
434 new_profile
= aa_get_profile(profile
);
436 } else if (perms
.xindex
& AA_X_UNCONFINED
) {
437 new_profile
= aa_get_newest_profile(ns
->unconfined
);
438 info
= "ux fallback";
441 info
= "profile not found";
442 /* remove MAY_EXEC to audit as failure */
443 perms
.allow
&= ~MAY_EXEC
;
446 } else if (COMPLAIN_MODE(profile
)) {
447 /* no exec permission - are we in learning mode */
448 new_profile
= aa_new_null_profile(profile
, 0);
451 info
= "could not create null profile";
454 target
= new_profile
->base
.hname
;
456 perms
.xindex
|= AA_X_UNSAFE
;
462 * Policy has specified a domain transition, if no_new_privs then
465 if (bprm
->unsafe
& LSM_UNSAFE_NO_NEW_PRIVS
) {
466 aa_put_profile(new_profile
);
474 if (bprm
->unsafe
& LSM_UNSAFE_SHARE
) {
475 /* FIXME: currently don't mediate shared state */
479 if (bprm
->unsafe
& (LSM_UNSAFE_PTRACE
| LSM_UNSAFE_PTRACE_CAP
)) {
480 error
= may_change_ptraced_domain(current
, new_profile
);
482 aa_put_profile(new_profile
);
487 /* Determine if secure exec is needed.
488 * Can be at this point for the following reasons:
489 * 1. unconfined switching to confined
490 * 2. confined switching to different confinement
491 * 3. confined switching to unconfined
493 * Cases 2 and 3 are marked as requiring secure exec
494 * (unless policy specified "unsafe exec")
496 * bprm->unsafe is used to cache the AA_X_UNSAFE permission
497 * to avoid having to recompute in secureexec
499 if (!(perms
.xindex
& AA_X_UNSAFE
)) {
500 AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
501 name
, new_profile
->base
.hname
);
502 bprm
->unsafe
|= AA_SECURE_X_NEEDED
;
505 target
= new_profile
->base
.hname
;
506 /* when transitioning profiles clear unsafe personality bits */
507 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
510 aa_put_profile(cxt
->profile
);
511 /* transfer new profile reference will be released when cxt is freed */
512 cxt
->profile
= new_profile
;
514 /* clear out all temporary/transitional state from the context */
515 aa_clear_task_cxt_trans(cxt
);
518 error
= aa_audit_file(profile
, &perms
, GFP_KERNEL
, OP_EXEC
, MAY_EXEC
,
519 name
, target
, cond
.uid
, info
, error
);
522 aa_put_profile(profile
);
529 * apparmor_bprm_secureexec - determine if secureexec is needed
530 * @bprm: binprm for exec (NOT NULL)
532 * Returns: %1 if secureexec is needed else %0
534 int apparmor_bprm_secureexec(struct linux_binprm
*bprm
)
536 int ret
= cap_bprm_secureexec(bprm
);
538 /* the decision to use secure exec is computed in set_creds
539 * and stored in bprm->unsafe.
541 if (!ret
&& (bprm
->unsafe
& AA_SECURE_X_NEEDED
))
548 * apparmor_bprm_committing_creds - do task cleanup on committing new creds
549 * @bprm: binprm for the exec (NOT NULL)
551 void apparmor_bprm_committing_creds(struct linux_binprm
*bprm
)
553 struct aa_profile
*profile
= __aa_current_profile();
554 struct aa_task_cxt
*new_cxt
= cred_cxt(bprm
->cred
);
556 /* bail out if unconfined or not changing profile */
557 if ((new_cxt
->profile
== profile
) ||
558 (unconfined(new_cxt
->profile
)))
561 current
->pdeath_signal
= 0;
563 /* reset soft limits and set hard limits for the new profile */
564 __aa_transition_rlimits(profile
, new_cxt
->profile
);
568 * apparmor_bprm_commited_cred - do cleanup after new creds committed
569 * @bprm: binprm for the exec (NOT NULL)
571 void apparmor_bprm_committed_creds(struct linux_binprm
*bprm
)
573 /* TODO: cleanup signals - ipc mediation */
578 * Functions for self directed profile change
582 * new_compound_name - create an hname with @n2 appended to @n1
583 * @n1: base of hname (NOT NULL)
584 * @n2: name to append (NOT NULL)
586 * Returns: new name or NULL on error
588 static char *new_compound_name(const char *n1
, const char *n2
)
590 char *name
= kmalloc(strlen(n1
) + strlen(n2
) + 3, GFP_KERNEL
);
592 sprintf(name
, "%s//%s", n1
, n2
);
597 * aa_change_hat - change hat to/from subprofile
598 * @hats: vector of hat names to try changing into (MAYBE NULL if @count == 0)
599 * @count: number of hat names in @hats
600 * @token: magic value to validate the hat change
601 * @permtest: true if this is just a permission test
603 * Change to the first profile specified in @hats that exists, and store
604 * the @hat_magic in the current task context. If the count == 0 and the
605 * @token matches that stored in the current task context, return to the
608 * Returns %0 on success, error otherwise.
610 int aa_change_hat(const char *hats
[], int count
, u64 token
, bool permtest
)
612 const struct cred
*cred
;
613 struct aa_task_cxt
*cxt
;
614 struct aa_profile
*profile
, *previous_profile
, *hat
= NULL
;
617 struct file_perms perms
= {};
618 const char *target
= NULL
, *info
= NULL
;
622 * Fail explicitly requested domain transitions if no_new_privs.
623 * There is no exception for unconfined as change_hat is not
626 if (current
->no_new_privs
)
630 cred
= get_current_cred();
631 cxt
= cred_cxt(cred
);
632 profile
= aa_cred_profile(cred
);
633 previous_profile
= cxt
->previous
;
635 if (unconfined(profile
)) {
642 /* attempting to change into a new hat or switch to a sibling */
643 struct aa_profile
*root
;
644 if (PROFILE_IS_HAT(profile
))
645 root
= aa_get_profile_rcu(&profile
->parent
);
647 root
= aa_get_profile(profile
);
649 /* find first matching hat */
650 for (i
= 0; i
< count
&& !hat
; i
++)
652 hat
= aa_find_child(root
, hats
[i
]);
654 if (!COMPLAIN_MODE(root
) || permtest
) {
655 if (list_empty(&root
->base
.profiles
))
659 aa_put_profile(root
);
664 * In complain mode and failed to match any hats.
665 * Audit the failure is based off of the first hat
666 * supplied. This is done due how userspace
667 * interacts with change_hat.
669 * TODO: Add logging of all failed hats
673 name
= new_compound_name(root
->base
.hname
, hats
[0]);
674 aa_put_profile(root
);
677 hat
= aa_new_null_profile(profile
, 1);
679 info
= "failed null profile create";
684 aa_put_profile(root
);
685 target
= hat
->base
.hname
;
686 if (!PROFILE_IS_HAT(hat
)) {
687 info
= "target not hat";
693 error
= may_change_ptraced_domain(current
, hat
);
701 error
= aa_set_current_hat(hat
, token
);
702 if (error
== -EACCES
)
703 /* kill task in case of brute force attacks */
704 perms
.kill
= AA_MAY_CHANGEHAT
;
705 else if (name
&& !error
)
706 /* reset error for learning of new hats */
709 } else if (previous_profile
) {
710 /* Return to saved profile. Kill task if restore fails
711 * to avoid brute force attacks
713 target
= previous_profile
->base
.hname
;
714 error
= aa_restore_previous_profile(token
);
715 perms
.kill
= AA_MAY_CHANGEHAT
;
717 /* ignore restores when there is no saved profile */
722 error
= aa_audit_file(profile
, &perms
, GFP_KERNEL
,
723 OP_CHANGE_HAT
, AA_MAY_CHANGEHAT
, NULL
,
724 target
, GLOBAL_ROOT_UID
, info
, error
);
735 * aa_change_profile - perform a one-way profile transition
736 * @ns_name: name of the profile namespace to change to (MAYBE NULL)
737 * @hname: name of profile to change to (MAYBE NULL)
738 * @onexec: whether this transition is to take place immediately or at exec
739 * @permtest: true if this is just a permission test
741 * Change to new profile @name. Unlike with hats, there is no way
742 * to change back. If @name isn't specified the current profile name is
744 * If @onexec then the transition is delayed until
747 * Returns %0 on success, error otherwise.
749 int aa_change_profile(const char *ns_name
, const char *hname
, bool onexec
,
752 const struct cred
*cred
;
753 struct aa_profile
*profile
, *target
= NULL
;
754 struct aa_namespace
*ns
= NULL
;
755 struct file_perms perms
= {};
756 const char *name
= NULL
, *info
= NULL
;
760 if (!hname
&& !ns_name
)
764 request
= AA_MAY_ONEXEC
;
765 op
= OP_CHANGE_ONEXEC
;
767 request
= AA_MAY_CHANGE_PROFILE
;
768 op
= OP_CHANGE_PROFILE
;
771 cred
= get_current_cred();
772 profile
= aa_cred_profile(cred
);
775 * Fail explicitly requested domain transitions if no_new_privs
776 * and not unconfined.
777 * Domain transitions from unconfined are allowed even when
778 * no_new_privs is set because this aways results in a reduction
781 if (current
->no_new_privs
&& !unconfined(profile
)) {
788 ns
= aa_find_namespace(profile
->ns
, ns_name
);
790 /* we don't create new namespace in complain mode */
792 info
= "namespace not found";
798 ns
= aa_get_namespace(profile
->ns
);
800 /* if the name was not specified, use the name of the current profile */
802 if (unconfined(profile
))
803 hname
= ns
->unconfined
->base
.hname
;
805 hname
= profile
->base
.hname
;
808 perms
= change_profile_perms(profile
, ns
, hname
, request
,
809 profile
->file
.start
);
810 if (!(perms
.allow
& request
)) {
816 target
= aa_lookup_profile(ns
, hname
);
818 info
= "profile not found";
820 if (permtest
|| !COMPLAIN_MODE(profile
))
823 target
= aa_new_null_profile(profile
, 0);
825 info
= "failed null profile create";
831 /* check if tracing task is allowed to trace target domain */
832 error
= may_change_ptraced_domain(current
, target
);
834 info
= "ptrace prevents transition";
842 error
= aa_set_current_onexec(target
);
844 error
= aa_replace_current_profile(target
);
848 error
= aa_audit_file(profile
, &perms
, GFP_KERNEL
, op
, request
,
849 name
, hname
, GLOBAL_ROOT_UID
, info
, error
);
851 aa_put_namespace(ns
);
852 aa_put_profile(target
);