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selinux/stable-5.1 PR 20190305

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Merge tag 'selinux-pr-20190305' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull SELinux updates from Paul Moore:
 "Nine SELinux patches for v5.1, all bug fixes.

  As far as I'm concerned, nothing really jumps out as risky or special
  to me, but each commit has a decent description so you can judge for
  yourself. As usual, everything passes the selinux-testsuite; please
  merge for v5.1"

* tag 'selinux-pr-20190305' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: fix avc audit messages
  selinux: replace BUG_ONs with WARN_ONs in avc.c
  selinux: log invalid contexts in AVCs
  selinux: replace some BUG_ON()s with a WARN_ON()
  selinux: inline some AVC functions used only once
  selinux: do not override context on context mounts
  selinux: never allow relabeling on context mounts
  selinux: stop passing MAY_NOT_BLOCK to the AVC upon follow_link
  selinux: avoid silent denials in permissive mode under RCU walk
This commit is contained in:
Linus Torvalds 2019-03-07 12:12:45 -08:00
parent ae5906ceee 45189a1998
commit 3ac96c30cc
5 changed files with 176 additions and 127 deletions
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199
security/selinux/avc.c
View file

@ -129,75 +129,6 @@ static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
}
/**
* avc_dump_av - Display an access vector in human-readable form.
* @tclass: target security class
* @av: access vector
*/
static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
{
const char **perms;
int i, perm;
if (av == 0) {
audit_log_format(ab, " null");
return;
}
BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map));
perms = secclass_map[tclass-1].perms;
audit_log_format(ab, " {");
i = 0;
perm = 1;
while (i < (sizeof(av) * 8)) {
if ((perm & av) && perms[i]) {
audit_log_format(ab, " %s", perms[i]);
av &= ~perm;
}
i++;
perm <<= 1;
}
if (av)
audit_log_format(ab, " 0x%x", av);
audit_log_format(ab, " }");
}
/**
* avc_dump_query - Display a SID pair and a class in human-readable form.
* @ssid: source security identifier
* @tsid: target security identifier
* @tclass: target security class
*/
static void avc_dump_query(struct audit_buffer *ab, struct selinux_state *state,
u32 ssid, u32 tsid, u16 tclass)
{
int rc;
char *scontext;
u32 scontext_len;
rc = security_sid_to_context(state, ssid, &scontext, &scontext_len);
if (rc)
audit_log_format(ab, "ssid=%d", ssid);
else {
audit_log_format(ab, "scontext=%s", scontext);
kfree(scontext);
}
rc = security_sid_to_context(state, tsid, &scontext, &scontext_len);
if (rc)
audit_log_format(ab, " tsid=%d", tsid);
else {
audit_log_format(ab, " tcontext=%s", scontext);
kfree(scontext);
}
BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map));
audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
}
/**
* avc_init - Initialize the AVC.
*
@ -735,11 +666,36 @@ static struct avc_node *avc_insert(struct selinux_avc *avc,
static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
{
struct common_audit_data *ad = a;
audit_log_format(ab, "avc: %s ",
ad->selinux_audit_data->denied ? "denied" : "granted");
avc_dump_av(ab, ad->selinux_audit_data->tclass,
ad->selinux_audit_data->audited);
audit_log_format(ab, " for ");
struct selinux_audit_data *sad = ad->selinux_audit_data;
u32 av = sad->audited;
const char **perms;
int i, perm;
audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted");
if (av == 0) {
audit_log_format(ab, " null");
return;
}
perms = secclass_map[sad->tclass-1].perms;
audit_log_format(ab, " {");
i = 0;
perm = 1;
while (i < (sizeof(av) * 8)) {
if ((perm & av) && perms[i]) {
audit_log_format(ab, " %s", perms[i]);
av &= ~perm;
}
i++;
perm <<= 1;
}
if (av)
audit_log_format(ab, " 0x%x", av);
audit_log_format(ab, " } for ");
}
/**
@ -751,14 +707,47 @@ static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
{
struct common_audit_data *ad = a;
audit_log_format(ab, " ");
avc_dump_query(ab, ad->selinux_audit_data->state,
ad->selinux_audit_data->ssid,
ad->selinux_audit_data->tsid,
ad->selinux_audit_data->tclass);
if (ad->selinux_audit_data->denied) {
audit_log_format(ab, " permissive=%u",
ad->selinux_audit_data->result ? 0 : 1);
struct selinux_audit_data *sad = ad->selinux_audit_data;
char *scontext;
u32 scontext_len;
int rc;
rc = security_sid_to_context(sad->state, sad->ssid, &scontext,
&scontext_len);
if (rc)
audit_log_format(ab, " ssid=%d", sad->ssid);
else {
audit_log_format(ab, " scontext=%s", scontext);
kfree(scontext);
}
rc = security_sid_to_context(sad->state, sad->tsid, &scontext,
&scontext_len);
if (rc)
audit_log_format(ab, " tsid=%d", sad->tsid);
else {
audit_log_format(ab, " tcontext=%s", scontext);
kfree(scontext);
}
audit_log_format(ab, " tclass=%s", secclass_map[sad->tclass-1].name);
if (sad->denied)
audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
/* in case of invalid context report also the actual context string */
rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
&scontext_len);
if (!rc && scontext) {
audit_log_format(ab, " srawcon=%s", scontext);
kfree(scontext);
}
rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext,
&scontext_len);
if (!rc && scontext) {
audit_log_format(ab, " trawcon=%s", scontext);
kfree(scontext);
}
}
@ -772,6 +761,9 @@ noinline int slow_avc_audit(struct selinux_state *state,
struct common_audit_data stack_data;
struct selinux_audit_data sad;
if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
return -EINVAL;
if (!a) {
a = &stack_data;
a->type = LSM_AUDIT_DATA_NONE;
@ -838,6 +830,7 @@ int __init avc_add_callback(int (*callback)(u32 event), u32 events)
* @ssid,@tsid,@tclass : identifier of an AVC entry
* @seqno : sequence number when decision was made
* @xpd: extended_perms_decision to be added to the node
* @flags: the AVC_* flags, e.g. AVC_NONBLOCKING, AVC_EXTENDED_PERMS, or 0.
*
* if a valid AVC entry doesn't exist,this function returns -ENOENT.
* if kmalloc() called internal returns NULL, this function returns -ENOMEM.
@ -856,6 +849,22 @@ static int avc_update_node(struct selinux_avc *avc,
struct hlist_head *head;
spinlock_t *lock;
/*
* If we are in a non-blocking code path, e.g. VFS RCU walk,
* then we must not add permissions to a cache entry
* because we cannot safely audit the denial. Otherwise,
* during the subsequent blocking retry (e.g. VFS ref walk), we
* will find the permissions already granted in the cache entry
* and won't audit anything at all, leading to silent denials in
* permissive mode that only appear when in enforcing mode.
*
* See the corresponding handling in slow_avc_audit(), and the
* logic in selinux_inode_permission for the MAY_NOT_BLOCK flag,
* which is transliterated into AVC_NONBLOCKING.
*/
if (flags & AVC_NONBLOCKING)
return 0;
node = avc_alloc_node(avc);
if (!node) {
rc = -ENOMEM;
@ -1050,7 +1059,8 @@ int avc_has_extended_perms(struct selinux_state *state,
int rc = 0, rc2;
xp_node = &local_xp_node;
BUG_ON(!requested);
if (WARN_ON(!requested))
return -EACCES;
rcu_read_lock();
@ -1115,7 +1125,7 @@ int avc_has_extended_perms(struct selinux_state *state,
* @tsid: target security identifier
* @tclass: target security class
* @requested: requested permissions, interpreted based on @tclass
* @flags: AVC_STRICT or 0
* @flags: AVC_STRICT, AVC_NONBLOCKING, or 0
* @avd: access vector decisions
*
* Check the AVC to determine whether the @requested permissions are granted
@ -1140,7 +1150,8 @@ inline int avc_has_perm_noaudit(struct selinux_state *state,
int rc = 0;
u32 denied;
BUG_ON(!requested);
if (WARN_ON(!requested))
return -EACCES;
rcu_read_lock();
@ -1191,24 +1202,6 @@ int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
return rc;
}
int avc_has_perm_flags(struct selinux_state *state,
u32 ssid, u32 tsid, u16 tclass, u32 requested,
struct common_audit_data *auditdata,
int flags)
{
struct av_decision avd;
int rc, rc2;
rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
&avd);
rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
auditdata, flags);
if (rc2)
return rc2;
return rc;
}
u32 avc_policy_seqno(struct selinux_state *state)
{
return state->avc->avc_cache.latest_notif;

58
security/selinux/hooks.c
View file

@ -490,16 +490,10 @@ static int may_context_mount_inode_relabel(u32 sid,
return rc;
}
static int selinux_is_sblabel_mnt(struct super_block *sb)
static int selinux_is_genfs_special_handling(struct super_block *sb)
{
struct superblock_security_struct *sbsec = sb->s_security;
return sbsec->behavior == SECURITY_FS_USE_XATTR ||
sbsec->behavior == SECURITY_FS_USE_TRANS ||
sbsec->behavior == SECURITY_FS_USE_TASK ||
sbsec->behavior == SECURITY_FS_USE_NATIVE ||
/* Special handling. Genfs but also in-core setxattr handler */
!strcmp(sb->s_type->name, "sysfs") ||
/* Special handling. Genfs but also in-core setxattr handler */
return !strcmp(sb->s_type->name, "sysfs") ||
!strcmp(sb->s_type->name, "pstore") ||
!strcmp(sb->s_type->name, "debugfs") ||
!strcmp(sb->s_type->name, "tracefs") ||
@ -509,6 +503,34 @@ static int selinux_is_sblabel_mnt(struct super_block *sb)
!strcmp(sb->s_type->name, "cgroup2")));
}
static int selinux_is_sblabel_mnt(struct super_block *sb)
{
struct superblock_security_struct *sbsec = sb->s_security;
/*
* IMPORTANT: Double-check logic in this function when adding a new
* SECURITY_FS_USE_* definition!
*/
BUILD_BUG_ON(SECURITY_FS_USE_MAX != 7);
switch (sbsec->behavior) {
case SECURITY_FS_USE_XATTR:
case SECURITY_FS_USE_TRANS:
case SECURITY_FS_USE_TASK:
case SECURITY_FS_USE_NATIVE:
return 1;
case SECURITY_FS_USE_GENFS:
return selinux_is_genfs_special_handling(sb);
/* Never allow relabeling on context mounts */
case SECURITY_FS_USE_MNTPOINT:
case SECURITY_FS_USE_NONE:
default:
return 0;
}
}
static int sb_finish_set_opts(struct super_block *sb)
{
struct superblock_security_struct *sbsec = sb->s_security;
@ -2881,9 +2903,8 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct inode *inode,
if (IS_ERR(isec))
return PTR_ERR(isec);
return avc_has_perm_flags(&selinux_state,
sid, isec->sid, isec->sclass, FILE__READ, &ad,
rcu ? MAY_NOT_BLOCK : 0);
return avc_has_perm(&selinux_state,
sid, isec->sid, isec->sclass, FILE__READ, &ad);
}
static noinline int audit_inode_permission(struct inode *inode,
@ -2938,7 +2959,9 @@ static int selinux_inode_permission(struct inode *inode, int mask)
return PTR_ERR(isec);
rc = avc_has_perm_noaudit(&selinux_state,
sid, isec->sid, isec->sclass, perms, 0, &avd);
sid, isec->sid, isec->sclass, perms,
(flags & MAY_NOT_BLOCK) ? AVC_NONBLOCKING : 0,
&avd);
audited = avc_audit_required(perms, &avd, rc,
from_access ? FILE__AUDIT_ACCESS : 0,
&denied);
@ -3197,12 +3220,16 @@ static int selinux_inode_setsecurity(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
struct inode_security_struct *isec = inode_security_novalidate(inode);
struct superblock_security_struct *sbsec = inode->i_sb->s_security;
u32 newsid;
int rc;
if (strcmp(name, XATTR_SELINUX_SUFFIX))
return -EOPNOTSUPP;
if (!(sbsec->flags & SBLABEL_MNT))
return -EOPNOTSUPP;
if (!value || !size)
return -EACCES;
@ -6236,7 +6263,10 @@ static void selinux_inode_invalidate_secctx(struct inode *inode)
*/
static int selinux_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen)
{
return selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX, ctx, ctxlen, 0);
int rc = selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX,
ctx, ctxlen, 0);
/* Do not return error when suppressing label (SBLABEL_MNT not set). */
return rc == -EOPNOTSUPP ? 0 : rc;
}
/*

6
security/selinux/include/avc.h
View file

@ -142,6 +142,7 @@ static inline int avc_audit(struct selinux_state *state,
#define AVC_STRICT 1 /* Ignore permissive mode. */
#define AVC_EXTENDED_PERMS 2 /* update extended permissions */
#define AVC_NONBLOCKING 4 /* non blocking */
int avc_has_perm_noaudit(struct selinux_state *state,
u32 ssid, u32 tsid,
u16 tclass, u32 requested,
@ -152,11 +153,6 @@ int avc_has_perm(struct selinux_state *state,
u32 ssid, u32 tsid,
u16 tclass, u32 requested,
struct common_audit_data *auditdata);
int avc_has_perm_flags(struct selinux_state *state,
u32 ssid, u32 tsid,
u16 tclass, u32 requested,
struct common_audit_data *auditdata,
int flags);
int avc_has_extended_perms(struct selinux_state *state,
u32 ssid, u32 tsid, u16 tclass, u32 requested,

3
security/selinux/include/security.h
View file

@ -255,6 +255,9 @@ int security_sid_to_context(struct selinux_state *state, u32 sid,
int security_sid_to_context_force(struct selinux_state *state,
u32 sid, char **scontext, u32 *scontext_len);
int security_sid_to_context_inval(struct selinux_state *state,
u32 sid, char **scontext, u32 *scontext_len);
int security_context_to_sid(struct selinux_state *state,
const char *scontext, u32 scontext_len,
u32 *out_sid, gfp_t gfp);

37
security/selinux/ss/services.c
View file

@ -1280,7 +1280,8 @@ const char *security_get_initial_sid_context(u32 sid)
static int security_sid_to_context_core(struct selinux_state *state,
u32 sid, char **scontext,
u32 *scontext_len, int force)
u32 *scontext_len, int force,
int only_invalid)
{
struct policydb *policydb;
struct sidtab *sidtab;
@ -1325,8 +1326,14 @@ static int security_sid_to_context_core(struct selinux_state *state,
rc = -EINVAL;
goto out_unlock;
}
rc = context_struct_to_string(policydb, context, scontext,
scontext_len);
if (only_invalid && !context->len) {
scontext = NULL;
scontext_len = 0;
rc = 0;
} else {
rc = context_struct_to_string(policydb, context, scontext,
scontext_len);
}
out_unlock:
read_unlock(&state->ss->policy_rwlock);
out:
@ -1348,14 +1355,34 @@ int security_sid_to_context(struct selinux_state *state,
u32 sid, char **scontext, u32 *scontext_len)
{
return security_sid_to_context_core(state, sid, scontext,
scontext_len, 0);
scontext_len, 0, 0);
}
int security_sid_to_context_force(struct selinux_state *state, u32 sid,
char **scontext, u32 *scontext_len)
{
return security_sid_to_context_core(state, sid, scontext,
scontext_len, 1);
scontext_len, 1, 0);
}
/**
* security_sid_to_context_inval - Obtain a context for a given SID if it
* is invalid.
* @sid: security identifier, SID
* @scontext: security context
* @scontext_len: length in bytes
*
* Write the string representation of the context associated with @sid
* into a dynamically allocated string of the correct size, but only if the
* context is invalid in the current policy. Set @scontext to point to
* this string (or NULL if the context is valid) and set @scontext_len to
* the length of the string (or 0 if the context is valid).
*/
int security_sid_to_context_inval(struct selinux_state *state, u32 sid,
char **scontext, u32 *scontext_len)
{
return security_sid_to_context_core(state, sid, scontext,
scontext_len, 1, 1);
}
/*