Skip to content

Commit

Permalink
selinux: store role transitions in a hash table
Browse files Browse the repository at this point in the history 
Currently, they are stored in a linked list, which adds significant
overhead to security_transition_sid(). On Fedora, with 428 role
transitions in policy, converting this list to a hash table cuts down
its run time by about 50%. This was measured by running 'stress-ng --msg
1 --msg-ops 100000' under perf with and without this patch.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
  • Loading branch information
Ondrej Mosnacek authored and Paul Moore committed Apr 17, 2020
1 parent 433e3aa commit e67b2ec
Show file tree
Hide file tree
Showing 3 changed files with 107 additions and 60 deletions.
138 changes: 92 additions & 46 deletions security/selinux/ss/policydb.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -352,6 +352,13 @@ static int range_tr_destroy(void *key, void *datum, void *p)
return 0;
}

static int role_tr_destroy(void *key, void *datum, void *p)
{
kfree(key);
kfree(datum);
return 0;
}

static void ocontext_destroy(struct ocontext *c, int i)
{
if (!c)
Expand Down Expand Up @@ -458,6 +465,30 @@ static int rangetr_cmp(struct hashtab *h, const void *k1, const void *k2)
return v;
}

static u32 role_trans_hash(struct hashtab *h, const void *k)
{
const struct role_trans_key *key = k;

return (key->role + (key->type << 3) + (key->tclass << 5)) &
(h->size - 1);
}

static int role_trans_cmp(struct hashtab *h, const void *k1, const void *k2)
{
const struct role_trans_key *key1 = k1, *key2 = k2;
int v;

v = key1->role - key2->role;
if (v)
return v;

v = key1->type - key2->type;
if (v)
return v;

return key1->tclass - key2->tclass;
}

/*
* Initialize a policy database structure.
*/
Expand Down Expand Up @@ -728,7 +759,6 @@ void policydb_destroy(struct policydb *p)
struct genfs *g, *gtmp;
int i;
struct role_allow *ra, *lra = NULL;
struct role_trans *tr, *ltr = NULL;

for (i = 0; i < SYM_NUM; i++) {
cond_resched();
Expand Down Expand Up @@ -775,12 +805,8 @@ void policydb_destroy(struct policydb *p)

cond_policydb_destroy(p);

for (tr = p->role_tr; tr; tr = tr->next) {
cond_resched();
kfree(ltr);
ltr = tr;
}
kfree(ltr);
hashtab_map(p->role_tr, role_tr_destroy, NULL);
hashtab_destroy(p->role_tr);

for (ra = p->role_allow; ra; ra = ra->next) {
cond_resched();
Expand Down Expand Up @@ -2251,7 +2277,8 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
int policydb_read(struct policydb *p, void *fp)
{
struct role_allow *ra, *lra;
struct role_trans *tr, *ltr;
struct role_trans_key *rtk = NULL;
struct role_trans_datum *rtd = NULL;
int i, j, rc;
__le32 buf[4];
u32 len, nprim, nel;
Expand Down Expand Up @@ -2416,39 +2443,50 @@ int policydb_read(struct policydb *p, void *fp)
if (rc)
goto bad;
nel = le32_to_cpu(buf[0]);
ltr = NULL;

p->role_tr = hashtab_create(role_trans_hash, role_trans_cmp, nel);
if (!p->role_tr)
goto bad;
for (i = 0; i < nel; i++) {
rc = -ENOMEM;
tr = kzalloc(sizeof(*tr), GFP_KERNEL);
if (!tr)
rtk = kmalloc(sizeof(*rtk), GFP_KERNEL);
if (!rtk)
goto bad;
if (ltr)
ltr->next = tr;
else
p->role_tr = tr;

rc = -ENOMEM;
rtd = kmalloc(sizeof(*rtd), GFP_KERNEL);
if (!rtd)
goto bad;

rc = next_entry(buf, fp, sizeof(u32)*3);
if (rc)
goto bad;

rc = -EINVAL;
tr->role = le32_to_cpu(buf[0]);
tr->type = le32_to_cpu(buf[1]);
tr->new_role = le32_to_cpu(buf[2]);
rtk->role = le32_to_cpu(buf[0]);
rtk->type = le32_to_cpu(buf[1]);
rtd->new_role = le32_to_cpu(buf[2]);
if (p->policyvers >= POLICYDB_VERSION_ROLETRANS) {
rc = next_entry(buf, fp, sizeof(u32));
if (rc)
goto bad;
tr->tclass = le32_to_cpu(buf[0]);
rtk->tclass = le32_to_cpu(buf[0]);
} else
tr->tclass = p->process_class;
rtk->tclass = p->process_class;

rc = -EINVAL;
if (!policydb_role_isvalid(p, tr->role) ||
!policydb_type_isvalid(p, tr->type) ||
!policydb_class_isvalid(p, tr->tclass) ||
!policydb_role_isvalid(p, tr->new_role))
if (!policydb_role_isvalid(p, rtk->role) ||
!policydb_type_isvalid(p, rtk->type) ||
!policydb_class_isvalid(p, rtk->tclass) ||
!policydb_role_isvalid(p, rtd->new_role))
goto bad;

rc = hashtab_insert(p->role_tr, rtk, rtd);
if (rc)
goto bad;
ltr = tr;

rtk = NULL;
rtd = NULL;
}

rc = next_entry(buf, fp, sizeof(u32));
Expand Down Expand Up @@ -2536,6 +2574,8 @@ int policydb_read(struct policydb *p, void *fp)
out:
return rc;
bad:
kfree(rtk);
kfree(rtd);
policydb_destroy(p);
goto out;
}
Expand Down Expand Up @@ -2653,39 +2693,45 @@ static int cat_write(void *vkey, void *datum, void *ptr)
return 0;
}

static int role_trans_write(struct policydb *p, void *fp)
static int role_trans_write_one(void *key, void *datum, void *ptr)
{
struct role_trans *r = p->role_tr;
struct role_trans *tr;
struct role_trans_key *rtk = key;
struct role_trans_datum *rtd = datum;
struct policy_data *pd = ptr;
void *fp = pd->fp;
struct policydb *p = pd->p;
__le32 buf[3];
size_t nel;
int rc;

nel = 0;
for (tr = r; tr; tr = tr->next)
nel++;
buf[0] = cpu_to_le32(nel);
rc = put_entry(buf, sizeof(u32), 1, fp);
buf[0] = cpu_to_le32(rtk->role);
buf[1] = cpu_to_le32(rtk->type);
buf[2] = cpu_to_le32(rtd->new_role);
rc = put_entry(buf, sizeof(u32), 3, fp);
if (rc)
return rc;
for (tr = r; tr; tr = tr->next) {
buf[0] = cpu_to_le32(tr->role);
buf[1] = cpu_to_le32(tr->type);
buf[2] = cpu_to_le32(tr->new_role);
rc = put_entry(buf, sizeof(u32), 3, fp);
if (p->policyvers >= POLICYDB_VERSION_ROLETRANS) {
buf[0] = cpu_to_le32(rtk->tclass);
rc = put_entry(buf, sizeof(u32), 1, fp);
if (rc)
return rc;
if (p->policyvers >= POLICYDB_VERSION_ROLETRANS) {
buf[0] = cpu_to_le32(tr->tclass);
rc = put_entry(buf, sizeof(u32), 1, fp);
if (rc)
return rc;
}
}

return 0;
}

static int role_trans_write(struct policydb *p, void *fp)
{
struct policy_data pd = { .p = p, .fp = fp };
__le32 buf[1];
int rc;

buf[0] = cpu_to_le32(p->role_tr->nel);
rc = put_entry(buf, sizeof(u32), 1, fp);
if (rc)
return rc;

return hashtab_map(p->role_tr, role_trans_write_one, &pd);
}

static int role_allow_write(struct role_allow *r, void *fp)
{
struct role_allow *ra;
Expand Down
8 changes: 5 additions & 3 deletions security/selinux/ss/policydb.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -81,12 +81,14 @@ struct role_datum {
struct ebitmap types; /* set of authorized types for role */
};

struct role_trans {
struct role_trans_key {
u32 role; /* current role */
u32 type; /* program executable type, or new object type */
u32 tclass; /* process class, or new object class */
};

struct role_trans_datum {
u32 new_role; /* new role */
struct role_trans *next;
};

struct filename_trans_key {
Expand Down Expand Up @@ -261,7 +263,7 @@ struct policydb {
struct avtab te_avtab;

/* role transitions */
struct role_trans *role_tr;
struct hashtab *role_tr;

/* file transitions with the last path component */
/* quickly exclude lookups when parent ttype has no rules */
Expand Down
21 changes: 10 additions & 11 deletions security/selinux/ss/services.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1731,7 +1731,6 @@ static int security_compute_sid(struct selinux_state *state,
struct class_datum *cladatum = NULL;
struct context *scontext, *tcontext, newcontext;
struct sidtab_entry *sentry, *tentry;
struct role_trans *roletr = NULL;
struct avtab_key avkey;
struct avtab_datum *avdatum;
struct avtab_node *node;
Expand Down Expand Up @@ -1864,16 +1863,16 @@ static int security_compute_sid(struct selinux_state *state,
/* Check for class-specific changes. */
if (specified & AVTAB_TRANSITION) {
/* Look for a role transition rule. */
for (roletr = policydb->role_tr; roletr;
roletr = roletr->next) {
if ((roletr->role == scontext->role) &&
(roletr->type == tcontext->type) &&
(roletr->tclass == tclass)) {
/* Use the role transition rule. */
newcontext.role = roletr->new_role;
break;
}
}
struct role_trans_datum *rtd;
struct role_trans_key rtk = {
.role = scontext->role,
.type = tcontext->type,
.tclass = tclass,
};

rtd = hashtab_search(policydb->role_tr, &rtk);
if (rtd)
newcontext.role = rtd->new_role;
}

/* Set the MLS attributes.
Expand Down

0 comments on commit e67b2ec

Please sign in to comment.