From 19439d05b88dafc4e55d9ffce84ccc27cf8b2bcc Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Thu, 14 Jan 2010 17:28:10 -0500 Subject: selinux: change the handling of unknown classes If allow_unknown==deny, SELinux treats an undefined kernel security class as an error condition rather than as a typical permission denial and thus does not allow permissions on undefined classes even when in permissive mode. Change the SELinux logic so that this case is handled as a typical permission denial, subject to the usual permissive mode and permissive domain handling. Also drop the 'requested' argument from security_compute_av() and helpers as it is a legacy of the original security server interface and is unused. Changes: - Handle permissive domains consistently by moving up the test for a permissive domain. - Make security_compute_av_user() consistent with security_compute_av(); the only difference now is that security_compute_av() performs mapping between the kernel-private class and permission indices and the policy values. In the userspace case, this mapping is handled by libselinux. - Moved avd_init inside the policy lock. Based in part on a patch by Paul Moore . Reported-by: Andrew Worsley Signed-off-by: Stephen D. Smalley Reviewed-by: Paul Moore Signed-off-by: James Morris --- security/selinux/avc.c | 5 +- security/selinux/include/security.h | 10 +- security/selinux/selinuxfs.c | 7 +- security/selinux/ss/services.c | 186 ++++++++++++++++-------------------- 4 files changed, 88 insertions(+), 120 deletions(-) (limited to 'security/selinux') diff --git a/security/selinux/avc.c b/security/selinux/avc.c index f2dde268165a..3ee9b6a8beb6 100644 --- a/security/selinux/avc.c +++ b/security/selinux/avc.c @@ -746,9 +746,7 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid, else avd = &avd_entry; - rc = security_compute_av(ssid, tsid, tclass, requested, avd); - if (rc) - goto out; + security_compute_av(ssid, tsid, tclass, avd); rcu_read_lock(); node = avc_insert(ssid, tsid, tclass, avd); } else { @@ -770,7 +768,6 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid, } rcu_read_unlock(); -out: return rc; } diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h index 2553266ad793..022cf067aa3f 100644 --- a/security/selinux/include/security.h +++ b/security/selinux/include/security.h @@ -96,13 +96,11 @@ struct av_decision { /* definitions of av_decision.flags */ #define AVD_FLAGS_PERMISSIVE 0x0001 -int security_compute_av(u32 ssid, u32 tsid, - u16 tclass, u32 requested, - struct av_decision *avd); +void security_compute_av(u32 ssid, u32 tsid, + u16 tclass, struct av_decision *avd); -int security_compute_av_user(u32 ssid, u32 tsid, - u16 tclass, u32 requested, - struct av_decision *avd); +void security_compute_av_user(u32 ssid, u32 tsid, + u16 tclass, struct av_decision *avd); int security_transition_sid(u32 ssid, u32 tsid, u16 tclass, u32 *out_sid); diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c index fab36fdf2769..b7bb0f5ec07c 100644 --- a/security/selinux/selinuxfs.c +++ b/security/selinux/selinuxfs.c @@ -494,7 +494,6 @@ static ssize_t sel_write_access(struct file *file, char *buf, size_t size) char *scon, *tcon; u32 ssid, tsid; u16 tclass; - u32 req; struct av_decision avd; ssize_t length; @@ -512,7 +511,7 @@ static ssize_t sel_write_access(struct file *file, char *buf, size_t size) goto out; length = -EINVAL; - if (sscanf(buf, "%s %s %hu %x", scon, tcon, &tclass, &req) != 4) + if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3) goto out2; length = security_context_to_sid(scon, strlen(scon)+1, &ssid); @@ -522,9 +521,7 @@ static ssize_t sel_write_access(struct file *file, char *buf, size_t size) if (length < 0) goto out2; - length = security_compute_av_user(ssid, tsid, tclass, req, &avd); - if (length < 0) - goto out2; + security_compute_av_user(ssid, tsid, tclass, &avd); length = scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%x %x %x %x %u %x", diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index 07ddc81d7b57..9ec24169ccd7 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -87,11 +87,10 @@ static u32 latest_granting; static int context_struct_to_string(struct context *context, char **scontext, u32 *scontext_len); -static int context_struct_compute_av(struct context *scontext, - struct context *tcontext, - u16 tclass, - u32 requested, - struct av_decision *avd); +static void context_struct_compute_av(struct context *scontext, + struct context *tcontext, + u16 tclass, + struct av_decision *avd); struct selinux_mapping { u16 value; /* policy value */ @@ -196,23 +195,6 @@ static u16 unmap_class(u16 tclass) return tclass; } -static u32 unmap_perm(u16 tclass, u32 tperm) -{ - if (tclass < current_mapping_size) { - unsigned i; - u32 kperm = 0; - - for (i = 0; i < current_mapping[tclass].num_perms; i++) - if (tperm & (1<allowed) == avd->allowed) return; /* no masked permission */ @@ -569,7 +549,6 @@ static void type_attribute_bounds_av(struct context *scontext, context_struct_compute_av(scontext, &lo_tcontext, tclass, - requested, &lo_avd); if ((lo_avd.allowed & avd->allowed) == avd->allowed) return; /* no masked permission */ @@ -586,7 +565,6 @@ static void type_attribute_bounds_av(struct context *scontext, context_struct_compute_av(&lo_scontext, &lo_tcontext, tclass, - requested, &lo_avd); if ((lo_avd.allowed & avd->allowed) == avd->allowed) return; /* no masked permission */ @@ -607,11 +585,10 @@ static void type_attribute_bounds_av(struct context *scontext, * Compute access vectors based on a context structure pair for * the permissions in a particular class. */ -static int context_struct_compute_av(struct context *scontext, - struct context *tcontext, - u16 tclass, - u32 requested, - struct av_decision *avd) +static void context_struct_compute_av(struct context *scontext, + struct context *tcontext, + u16 tclass, + struct av_decision *avd) { struct constraint_node *constraint; struct role_allow *ra; @@ -622,19 +599,14 @@ static int context_struct_compute_av(struct context *scontext, struct ebitmap_node *snode, *tnode; unsigned int i, j; - /* - * Initialize the access vectors to the default values. - */ avd->allowed = 0; avd->auditallow = 0; avd->auditdeny = 0xffffffff; - avd->seqno = latest_granting; - avd->flags = 0; if (unlikely(!tclass || tclass > policydb.p_classes.nprim)) { if (printk_ratelimit()) printk(KERN_WARNING "SELinux: Invalid class %hu\n", tclass); - return -EINVAL; + return; } tclass_datum = policydb.class_val_to_struct[tclass - 1]; @@ -705,9 +677,7 @@ static int context_struct_compute_av(struct context *scontext, * permission and notice it to userspace via audit. */ type_attribute_bounds_av(scontext, tcontext, - tclass, requested, avd); - - return 0; + tclass, avd); } static int security_validtrans_handle_fail(struct context *ocontext, @@ -886,110 +856,116 @@ out: return rc; } - -static int security_compute_av_core(u32 ssid, - u32 tsid, - u16 tclass, - u32 requested, - struct av_decision *avd) +static void avd_init(struct av_decision *avd) { - struct context *scontext = NULL, *tcontext = NULL; - int rc = 0; - - scontext = sidtab_search(&sidtab, ssid); - if (!scontext) { - printk(KERN_ERR "SELinux: %s: unrecognized SID %d\n", - __func__, ssid); - return -EINVAL; - } - tcontext = sidtab_search(&sidtab, tsid); - if (!tcontext) { - printk(KERN_ERR "SELinux: %s: unrecognized SID %d\n", - __func__, tsid); - return -EINVAL; - } - - rc = context_struct_compute_av(scontext, tcontext, tclass, - requested, avd); - - /* permissive domain? */ - if (ebitmap_get_bit(&policydb.permissive_map, scontext->type)) - avd->flags |= AVD_FLAGS_PERMISSIVE; - - return rc; + avd->allowed = 0; + avd->auditallow = 0; + avd->auditdeny = 0xffffffff; + avd->seqno = latest_granting; + avd->flags = 0; } + /** * security_compute_av - Compute access vector decisions. * @ssid: source security identifier * @tsid: target security identifier * @tclass: target security class - * @requested: requested permissions * @avd: access vector decisions * * Compute a set of access vector decisions based on the * SID pair (@ssid, @tsid) for the permissions in @tclass. - * Return -%EINVAL if any of the parameters are invalid or %0 - * if the access vector decisions were computed successfully. */ -int security_compute_av(u32 ssid, - u32 tsid, - u16 orig_tclass, - u32 orig_requested, - struct av_decision *avd) +void security_compute_av(u32 ssid, + u32 tsid, + u16 orig_tclass, + struct av_decision *avd) { u16 tclass; - u32 requested; - int rc; + struct context *scontext = NULL, *tcontext = NULL; read_lock(&policy_rwlock); - + avd_init(avd); if (!ss_initialized) goto allow; - requested = unmap_perm(orig_tclass, orig_requested); + scontext = sidtab_search(&sidtab, ssid); + if (!scontext) { + printk(KERN_ERR "SELinux: %s: unrecognized SID %d\n", + __func__, ssid); + goto out; + } + + /* permissive domain? */ + if (ebitmap_get_bit(&policydb.permissive_map, scontext->type)) + avd->flags |= AVD_FLAGS_PERMISSIVE; + + tcontext = sidtab_search(&sidtab, tsid); + if (!tcontext) { + printk(KERN_ERR "SELinux: %s: unrecognized SID %d\n", + __func__, tsid); + goto out; + } + tclass = unmap_class(orig_tclass); if (unlikely(orig_tclass && !tclass)) { if (policydb.allow_unknown) goto allow; - rc = -EINVAL; goto out; } - rc = security_compute_av_core(ssid, tsid, tclass, requested, avd); + context_struct_compute_av(scontext, tcontext, tclass, avd); map_decision(orig_tclass, avd, policydb.allow_unknown); out: read_unlock(&policy_rwlock); - return rc; + return; allow: avd->allowed = 0xffffffff; - avd->auditallow = 0; - avd->auditdeny = 0xffffffff; - avd->seqno = latest_granting; - avd->flags = 0; - rc = 0; goto out; } -int security_compute_av_user(u32 ssid, - u32 tsid, - u16 tclass, - u32 requested, - struct av_decision *avd) +void security_compute_av_user(u32 ssid, + u32 tsid, + u16 tclass, + struct av_decision *avd) { - int rc; + struct context *scontext = NULL, *tcontext = NULL; - if (!ss_initialized) { - avd->allowed = 0xffffffff; - avd->auditallow = 0; - avd->auditdeny = 0xffffffff; - avd->seqno = latest_granting; - return 0; + read_lock(&policy_rwlock); + avd_init(avd); + if (!ss_initialized) + goto allow; + + scontext = sidtab_search(&sidtab, ssid); + if (!scontext) { + printk(KERN_ERR "SELinux: %s: unrecognized SID %d\n", + __func__, ssid); + goto out; } - read_lock(&policy_rwlock); - rc = security_compute_av_core(ssid, tsid, tclass, requested, avd); + /* permissive domain? */ + if (ebitmap_get_bit(&policydb.permissive_map, scontext->type)) + avd->flags |= AVD_FLAGS_PERMISSIVE; + + tcontext = sidtab_search(&sidtab, tsid); + if (!tcontext) { + printk(KERN_ERR "SELinux: %s: unrecognized SID %d\n", + __func__, tsid); + goto out; + } + + if (unlikely(!tclass)) { + if (policydb.allow_unknown) + goto allow; + goto out; + } + + context_struct_compute_av(scontext, tcontext, tclass, avd); + out: read_unlock(&policy_rwlock); - return rc; + return; +allow: + avd->allowed = 0xffffffff; + goto out; } /* -- cgit v1.2.3-59-g8ed1b