@@ -3732,8 +3732,8 @@ static int do_setattr(u64 attr, void *value, size_t size)
struct task_smack *tsp = smack_cred(current_cred());
struct cred *new;
struct smack_known *skp;
- struct smack_known_list_elem *sklep;
- int rc;
+ char *labelstr;
+ int rc = 0;
if (!smack_privileged(CAP_MAC_ADMIN) && list_empty(&tsp->smk_relabel))
return -EPERM;
@@ -3744,28 +3744,41 @@ static int do_setattr(u64 attr, void *value, size_t size)
if (attr != LSM_ATTR_CURRENT)
return -EOPNOTSUPP;
- skp = smk_import_entry(value, size);
- if (IS_ERR(skp))
- return PTR_ERR(skp);
+ labelstr = smk_parse_smack(value, size);
+ if (IS_ERR(labelstr))
+ return PTR_ERR(labelstr);
/*
* No process is ever allowed the web ("@") label
* and the star ("*") label.
*/
- if (skp == &smack_known_web || skp == &smack_known_star)
- return -EINVAL;
+ if (labelstr[1] == '\0' /* '@', '*' */) {
+ const char c = labelstr[0];
+
+ if (c == *smack_known_web.smk_known ||
+ c == *smack_known_star.smk_known) {
+ rc = -EPERM;
+ goto free_labelstr;
+ }
+ }
if (!smack_privileged(CAP_MAC_ADMIN)) {
- rc = -EPERM;
+ const struct smack_known_list_elem *sklep;
list_for_each_entry(sklep, &tsp->smk_relabel, list)
- if (sklep->smk_label == skp) {
- rc = 0;
- break;
- }
- if (rc)
- return rc;
+ if (strcmp(sklep->smk_label->smk_known, labelstr) == 0)
+ goto free_labelstr;
+ rc = -EPERM;
}
+free_labelstr:
+ kfree(labelstr);
+ if (rc)
+ return -EPERM;
+
+ skp = smk_import_entry(value, size);
+ if (IS_ERR(skp))
+ return PTR_ERR(skp);
+
new = prepare_creds();
if (new == NULL)
return -ENOMEM;
If an unprivileged task is allowed to relabel itself (/smack/relabel-self is not empty), it can freely create new labels by writing their names into own /proc/PID/attr/smack/current This occurs because do_setattr() imports the provided label in advance, before checking "relabel-self" list. This change ensures that the "relabel-self" list is checked before importing the label. Fixes: 38416e53936e ("Smack: limited capability for changing process label") Signed-off-by: Konstantin Andreev <andreev@swemel.ru> --- v2: removed space between smack_known_web and .smk_known security/smack/smack_lsm.c | 41 +++++++++++++++++++++++++------------- 1 file changed, 27 insertions(+), 14 deletions(-)