diff options
Diffstat (limited to 'security')
| -rw-r--r-- | security/apparmor/domain.c | 35 | ||||
| -rw-r--r-- | security/commoncap.c | 7 | ||||
| -rw-r--r-- | security/selinux/hooks.c | 10 | ||||
| -rw-r--r-- | security/yama/yama_lsm.c | 63 |
4 files changed, 100 insertions, 15 deletions
diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c index 6327685c101..b81ea10a17a 100644 --- a/security/apparmor/domain.c +++ b/security/apparmor/domain.c @@ -394,6 +394,11 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm) new_profile = find_attach(ns, &ns->base.profiles, name); if (!new_profile) goto cleanup; + /* + * NOTE: Domain transitions from unconfined are allowed + * even when no_new_privs is set because this aways results + * in a further reduction of permissions. + */ goto apply; } @@ -455,6 +460,16 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm) /* fail exec */ error = -EACCES; + /* + * Policy has specified a domain transition, if no_new_privs then + * fail the exec. + */ + if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) { + aa_put_profile(new_profile); + error = -EPERM; + goto cleanup; + } + if (!new_profile) goto audit; @@ -609,6 +624,14 @@ int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) const char *target = NULL, *info = NULL; int error = 0; + /* + * Fail explicitly requested domain transitions if no_new_privs. + * There is no exception for unconfined as change_hat is not + * available. + */ + if (current->no_new_privs) + return -EPERM; + /* released below */ cred = get_current_cred(); cxt = cred->security; @@ -750,6 +773,18 @@ int aa_change_profile(const char *ns_name, const char *hname, bool onexec, cxt = cred->security; profile = aa_cred_profile(cred); + /* + * Fail explicitly requested domain transitions if no_new_privs + * and not unconfined. + * Domain transitions from unconfined are allowed even when + * no_new_privs is set because this aways results in a reduction + * of permissions. + */ + if (current->no_new_privs && !unconfined(profile)) { + put_cred(cred); + return -EPERM; + } + if (ns_name) { /* released below */ ns = aa_find_namespace(profile->ns, ns_name); diff --git a/security/commoncap.c b/security/commoncap.c index 71a166a0597..f80d1160939 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -512,14 +512,17 @@ skip: /* Don't let someone trace a set[ug]id/setpcap binary with the revised - * credentials unless they have the appropriate permit + * credentials unless they have the appropriate permit. + * + * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. */ if ((new->euid != old->uid || new->egid != old->gid || !cap_issubset(new->cap_permitted, old->cap_permitted)) && bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) { /* downgrade; they get no more than they had, and maybe less */ - if (!capable(CAP_SETUID)) { + if (!capable(CAP_SETUID) || + (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { new->euid = new->uid; new->egid = new->gid; } diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index d85b793c932..0b06685787b 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2016,6 +2016,13 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm) new_tsec->sid = old_tsec->exec_sid; /* Reset exec SID on execve. */ new_tsec->exec_sid = 0; + + /* + * Minimize confusion: if no_new_privs and a transition is + * explicitly requested, then fail the exec. + */ + if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) + return -EPERM; } else { /* Check for a default transition on this program. */ rc = security_transition_sid(old_tsec->sid, isec->sid, @@ -2029,7 +2036,8 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm) ad.selinux_audit_data = &sad; ad.u.path = bprm->file->f_path; - if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) + if ((bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) || + (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) new_tsec->sid = old_tsec->sid; if (new_tsec->sid == old_tsec->sid) { diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index 573723843a0..c852f7472ad 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -18,7 +18,12 @@ #include <linux/prctl.h> #include <linux/ratelimit.h> -static int ptrace_scope = 1; +#define YAMA_SCOPE_DISABLED 0 +#define YAMA_SCOPE_RELATIONAL 1 +#define YAMA_SCOPE_CAPABILITY 2 +#define YAMA_SCOPE_NO_ATTACH 3 + +static int ptrace_scope = YAMA_SCOPE_RELATIONAL; /* describe a ptrace relationship for potential exception */ struct ptrace_relation { @@ -251,17 +256,32 @@ static int yama_ptrace_access_check(struct task_struct *child, return rc; /* require ptrace target be a child of ptracer on attach */ - if (mode == PTRACE_MODE_ATTACH && - ptrace_scope && - !task_is_descendant(current, child) && - !ptracer_exception_found(current, child) && - !capable(CAP_SYS_PTRACE)) - rc = -EPERM; + if (mode == PTRACE_MODE_ATTACH) { + switch (ptrace_scope) { + case YAMA_SCOPE_DISABLED: + /* No additional restrictions. */ + break; + case YAMA_SCOPE_RELATIONAL: + if (!task_is_descendant(current, child) && + !ptracer_exception_found(current, child) && + !capable(CAP_SYS_PTRACE)) + rc = -EPERM; + break; + case YAMA_SCOPE_CAPABILITY: + if (!capable(CAP_SYS_PTRACE)) + rc = -EPERM; + break; + case YAMA_SCOPE_NO_ATTACH: + default: + rc = -EPERM; + break; + } + } if (rc) { char name[sizeof(current->comm)]; - printk_ratelimited(KERN_NOTICE "ptrace of non-child" - " pid %d was attempted by: %s (pid %d)\n", + printk_ratelimited(KERN_NOTICE + "ptrace of pid %d was attempted by: %s (pid %d)\n", child->pid, get_task_comm(name, current), current->pid); @@ -279,8 +299,27 @@ static struct security_operations yama_ops = { }; #ifdef CONFIG_SYSCTL +static int yama_dointvec_minmax(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + int rc; + + if (write && !capable(CAP_SYS_PTRACE)) + return -EPERM; + + rc = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + if (rc) + return rc; + + /* Lock the max value if it ever gets set. */ + if (write && *(int *)table->data == *(int *)table->extra2) + table->extra1 = table->extra2; + + return rc; +} + static int zero; -static int one = 1; +static int max_scope = YAMA_SCOPE_NO_ATTACH; struct ctl_path yama_sysctl_path[] = { { .procname = "kernel", }, @@ -294,9 +333,9 @@ static struct ctl_table yama_sysctl_table[] = { .data = &ptrace_scope, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec_minmax, + .proc_handler = yama_dointvec_minmax, .extra1 = &zero, - .extra2 = &one, + .extra2 = &max_scope, }, { } }; |