Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932169AbaFKD1i (ORCPT ); Tue, 10 Jun 2014 23:27:38 -0400 Received: from smtp.outflux.net ([198.145.64.163]:59160 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751634AbaFKD0M (ORCPT ); Tue, 10 Jun 2014 23:26:12 -0400 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , Andy Lutomirski , Oleg Nesterov , Will Drewry , Julien Tinnes , David Drysdale , Alexei Starovoitov , John Johansen , Andrew Morton , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v6 4/9] seccomp: move no_new_privs into seccomp Date: Tue, 10 Jun 2014 20:25:16 -0700 Message-Id: <1402457121-8410-5-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1402457121-8410-1-git-send-email-keescook@chromium.org> References: <1402457121-8410-1-git-send-email-keescook@chromium.org> X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since seccomp transitions between threads requires updates to the no_new_privs flag to be atomic, changes must be atomic. This moves the nnp flag into the seccomp field as a separate unsigned long for atomic access. Signed-off-by: Kees Cook Acked-by: Andy Lutomirski --- fs/exec.c | 4 ++-- include/linux/sched.h | 13 ++++++++++--- include/linux/seccomp.h | 8 +++++++- kernel/seccomp.c | 2 +- kernel/sys.c | 4 ++-- security/apparmor/domain.c | 4 ++-- 6 files changed, 24 insertions(+), 11 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 238b7aa26f68..614fcb993739 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1233,7 +1233,7 @@ static void check_unsafe_exec(struct linux_binprm *bprm) * This isn't strictly necessary, but it makes it harder for LSMs to * mess up. */ - if (current->no_new_privs) + if (task_no_new_privs(current)) bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS; t = p; @@ -1271,7 +1271,7 @@ int prepare_binprm(struct linux_binprm *bprm) bprm->cred->egid = current_egid(); if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) && - !current->no_new_privs && + !task_no_new_privs(current) && kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) && kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) { /* Set-uid? */ diff --git a/include/linux/sched.h b/include/linux/sched.h index ea74596014a2..50b41affb7b1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1307,9 +1307,6 @@ struct task_struct { * execve */ unsigned in_iowait:1; - /* task may not gain privileges */ - unsigned no_new_privs:1; - /* Revert to default priority/policy when forking */ unsigned sched_reset_on_fork:1; unsigned sched_contributes_to_load:1; @@ -2525,6 +2522,16 @@ static inline void task_unlock(struct task_struct *p) spin_unlock(&p->alloc_lock); } +static inline bool task_no_new_privs(struct task_struct *p) +{ + return test_bit(SECCOMP_FLAG_NO_NEW_PRIVS, &p->seccomp.flags); +} + +static inline void task_set_no_new_privs(struct task_struct *p) +{ + set_bit(SECCOMP_FLAG_NO_NEW_PRIVS, &p->seccomp.flags); +} + extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, unsigned long *flags); diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index 9ff98b4bfe2e..6a5e2d0ec912 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -3,6 +3,8 @@ #include +#define SECCOMP_FLAG_NO_NEW_PRIVS 0 /* task may not gain privs */ + #ifdef CONFIG_SECCOMP #include @@ -16,6 +18,7 @@ struct seccomp_filter; * system calls available to a process. * @filter: must always point to a valid seccomp-filter or NULL as it is * accessed without locking during system call entry. + * @flags: flags under task->sighand->siglock lock * * @filter must only be accessed from the context of current as there * is no read locking. @@ -23,6 +26,7 @@ struct seccomp_filter; struct seccomp { int mode; struct seccomp_filter *filter; + unsigned long flags; }; extern int __secure_computing(int); @@ -51,7 +55,9 @@ static inline int seccomp_mode(struct seccomp *s) #include -struct seccomp { }; +struct seccomp { + unsigned long flags; +}; struct seccomp_filter { }; static inline int secure_computing(int this_syscall) { return 0; } diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 33655302b658..7ec99b99e400 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -219,7 +219,7 @@ static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) * This avoids scenarios where unprivileged tasks can affect the * behavior of privileged children. */ - if (!current->no_new_privs && + if (!task_no_new_privs(current) && security_capable_noaudit(current_cred(), current_user_ns(), CAP_SYS_ADMIN) != 0) return ERR_PTR(-EACCES); diff --git a/kernel/sys.c b/kernel/sys.c index 66a751ebf9d9..ce8129192a26 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1990,12 +1990,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, if (arg2 != 1 || arg3 || arg4 || arg5) return -EINVAL; - current->no_new_privs = 1; + task_set_no_new_privs(current); break; case PR_GET_NO_NEW_PRIVS: if (arg2 || arg3 || arg4 || arg5) return -EINVAL; - return current->no_new_privs ? 1 : 0; + return task_no_new_privs(current) ? 1 : 0; case PR_GET_THP_DISABLE: if (arg2 || arg3 || arg4 || arg5) return -EINVAL; diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c index 452567d3a08e..d97cba3e3849 100644 --- a/security/apparmor/domain.c +++ b/security/apparmor/domain.c @@ -621,7 +621,7 @@ int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) * There is no exception for unconfined as change_hat is not * available. */ - if (current->no_new_privs) + if (task_no_new_privs(current)) return -EPERM; /* released below */ @@ -776,7 +776,7 @@ int aa_change_profile(const char *ns_name, const char *hname, bool onexec, * no_new_privs is set because this aways results in a reduction * of permissions. */ - if (current->no_new_privs && !unconfined(profile)) { + if (task_no_new_privs(current) && !unconfined(profile)) { put_cred(cred); return -EPERM; } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/