1avc_has_perm(3) SELinux API documentation avc_has_perm(3)
2
6 avc_has_perm, avc_has_perm_noaudit, avc_audit, avc_entry_ref_init -
7 obtain and audit SELinux access decisions
8
10 #include <selinux/selinux.h>
11 #include <selinux/avc.h>
12 void avc_entry_ref_init(struct avc_entry_ref *aeref);
14 int avc_has_perm(security_id_t ssid, security_id_t tsid,
16 security_class_t tclass, access_vector_t requested,
17 struct avc_entry_ref *aeref, void *auditdata);
18 int avc_has_perm_noaudit(security_id_t ssid, security_id_t tsid,
20 security_class_t tclass, access_vector_t requested,
21 struct avc_entry_ref *aeref, struct av_decision *avd);
22 void avc_audit(security_id_t ssid, security_id_t tsid,
24 security_class_t tclass, access_vector_t requested,
25 struct av_decision *avd, int result, void *auditdata);
26
28 avc_entry_ref_init() initializes an avc_entry_ref structure; see ENTRY
29 REFERENCES below. This function may be implemented as a macro.
30 avc_has_perm() checks whether the requested permissions are granted for
32 subject SID ssid and target SID tsid, interpreting the permissions
33 based on tclass and updating aeref, if non-NULL, to refer to a cache
34 entry with the resulting decision. The granting or denial of permis‐
35 sions is audited in accordance with the policy. The auditdata parame‐
36 ter is for supplemental auditing; see avc_audit() below.
37 avc_has_perm_noaudit() behaves as avc_has_perm() without producing an
39 audit message. The access decision is returned in avd and can be
40 passed to avc_audit() explicitly.
41 avc_audit() produces an audit message for the access query represented
43 by ssid, tsid, tclass, and requested, with a decision represented by
44 avd. Pass the value returned by avc_has_perm_noaudit() as result. The
45 auditdata parameter is passed to the user-supplied func_audit callback
46 and can be used to add supplemental information to the audit message;
47 see avc_init(3).
48
50 Entry references can be used to speed cache performance for repeated
51 queries on the same subject and target. The userspace AVC will check
52 the aeref argument, if supplied, before searching the cache on a per‐
53 mission query. After a query is performed, aeref will be updated to
54 reference the cache entry for that query. A subsequent query on the
55 same subject and target will then have the decision at hand without
56 having to walk the cache.
57 After declaring an avc_entry_ref structure, use avc_entry_ref_init() to
59 initialize it before passing it to avc_has_perm() or
60 avc_has_perm_noaudit() for the first time. Using an uninitialized
61 structure will produce undefined behavior.
62
64 If requested permissions are granted, zero is returned. If requested
65 permissions are denied or an error occurred, -1 is returned and errno
66 is set appropriately.
67 In permissive mode, zero will be returned and errno unchanged even if
69 permissions were denied. avc_has_perm() will still produce an audit
70 message in this case.
71
73 EACCES A requested permission was denied.
74 EINVAL The tclass and/or the security contexts referenced by ssid and
76 tsid are not recognized by the currently loaded policy.
77 ENOMEM An attempt to allocate memory failed.
79
81 Internal errors encountered by the userspace AVC may cause certain val‐
82 ues of errno to be returned unexpectedly. For example, netlink socket
83 errors may produce EACCES or EINVAL. Make sure that userspace object
84 managers are granted appropriate access to netlink by the policy.
85
87 Eamon Walsh <ewalsh@tycho.nsa.gov>
88
90 avc_init(3), avc_context_to_sid(3), avc_cache_stats(3),
91 avc_add_callback(3), security_compute_av(3), selinux(8)
92 27 May 2004 avc_has_perm(3)