diff options
Diffstat (limited to 'security/commoncap.c')
| -rw-r--r-- | security/commoncap.c | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/security/commoncap.c b/security/commoncap.c index cefad323a0b1..52ea01acb453 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -1302,21 +1302,38 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, & (old->securebits ^ arg2)) /*[1]*/ || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ - || (cap_capable(current_cred(), - current_cred()->user_ns, - CAP_SETPCAP, - CAP_OPT_NONE) != 0) /*[4]*/ /* * [1] no changing of bits that are locked * [2] no unlocking of locks * [3] no setting of unsupported bits - * [4] doing anything requires privilege (go read about - * the "sendmail capabilities bug") */ ) /* cannot change a locked bit */ return -EPERM; + /* + * Doing anything requires privilege (go read about the + * "sendmail capabilities bug"), except for unprivileged bits. + * Indeed, the SECURE_ALL_UNPRIVILEGED bits are not + * restrictions enforced by the kernel but by user space on + * itself. + */ + if (cap_capable(current_cred(), current_cred()->user_ns, + CAP_SETPCAP, CAP_OPT_NONE) != 0) { + const unsigned long unpriv_and_locks = + SECURE_ALL_UNPRIVILEGED | + SECURE_ALL_UNPRIVILEGED << 1; + const unsigned long changed = old->securebits ^ arg2; + + /* For legacy reason, denies non-change. */ + if (!changed) + return -EPERM; + + /* Denies privileged changes. */ + if (changed & ~unpriv_and_locks) + return -EPERM; + } + new = prepare_creds(); if (!new) return -ENOMEM; |