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Merge tag 'seccomp-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux into next

This commit is contained in:
James Morris 2014-07-19 17:40:49 +10:00
parent 2ccf4661f3 c2e1f2e30d
commit fd33c43677
22 changed files with 472 additions and 81 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
MAINTAINERS
View File

@ -7953,6 +7953,16 @@ S: Maintained
F: drivers/mmc/host/sdhci.*
F: drivers/mmc/host/sdhci-pltfm.[ch]
SECURE COMPUTING
M: Kees Cook <keescook@chromium.org>
T: git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git seccomp
S: Supported
F: kernel/seccomp.c
F: include/uapi/linux/seccomp.h
F: include/linux/seccomp.h
K: \bsecure_computing
K: \bTIF_SECCOMP\b
SECURE DIGITAL HOST CONTROLLER INTERFACE, OPEN FIRMWARE BINDINGS (SDHCI-OF)
M: Anton Vorontsov <anton@enomsg.org>
L: linuxppc-dev@lists.ozlabs.org

1
arch/Kconfig
View File

@ -321,6 +321,7 @@ config HAVE_ARCH_SECCOMP_FILTER
- secure_computing is called from a ptrace_event()-safe context
- secure_computing return value is checked and a return value of -1
results in the system call being skipped immediately.
- seccomp syscall wired up
config SECCOMP_FILTER
def_bool y

1
arch/arm/include/uapi/asm/unistd.h
View File

@ -409,6 +409,7 @@
#define __NR_sched_setattr (__NR_SYSCALL_BASE+380)
#define __NR_sched_getattr (__NR_SYSCALL_BASE+381)
#define __NR_renameat2 (__NR_SYSCALL_BASE+382)
#define __NR_seccomp (__NR_SYSCALL_BASE+383)
/*
* This may need to be greater than __NR_last_syscall+1 in order to

1
arch/arm/kernel/calls.S
View File

@ -392,6 +392,7 @@
/* 380 */ CALL(sys_sched_setattr)
CALL(sys_sched_getattr)
CALL(sys_renameat2)
CALL(sys_seccomp)
#ifndef syscalls_counted
.equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
#define syscalls_counted

15
arch/mips/include/uapi/asm/unistd.h
View File

@ -372,16 +372,17 @@
#define __NR_sched_setattr (__NR_Linux + 349)
#define __NR_sched_getattr (__NR_Linux + 350)
#define __NR_renameat2 (__NR_Linux + 351)
#define __NR_seccomp (__NR_Linux + 352)
/*
* Offset of the last Linux o32 flavoured syscall
*/
#define __NR_Linux_syscalls 351
#define __NR_Linux_syscalls 352
#endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
#define __NR_O32_Linux 4000
#define __NR_O32_Linux_syscalls 351
#define __NR_O32_Linux_syscalls 352
#if _MIPS_SIM == _MIPS_SIM_ABI64
@ -701,16 +702,17 @@
#define __NR_sched_setattr (__NR_Linux + 309)
#define __NR_sched_getattr (__NR_Linux + 310)
#define __NR_renameat2 (__NR_Linux + 311)
#define __NR_seccomp (__NR_Linux + 312)
/*
* Offset of the last Linux 64-bit flavoured syscall
*/
#define __NR_Linux_syscalls 311
#define __NR_Linux_syscalls 312
#endif /* _MIPS_SIM == _MIPS_SIM_ABI64 */
#define __NR_64_Linux 5000
#define __NR_64_Linux_syscalls 311
#define __NR_64_Linux_syscalls 312
#if _MIPS_SIM == _MIPS_SIM_NABI32
@ -1034,15 +1036,16 @@
#define __NR_sched_setattr (__NR_Linux + 313)
#define __NR_sched_getattr (__NR_Linux + 314)
#define __NR_renameat2 (__NR_Linux + 315)
#define __NR_seccomp (__NR_Linux + 316)
/*
* Offset of the last N32 flavoured syscall
*/
#define __NR_Linux_syscalls 315
#define __NR_Linux_syscalls 316
#endif /* _MIPS_SIM == _MIPS_SIM_NABI32 */
#define __NR_N32_Linux 6000
#define __NR_N32_Linux_syscalls 315
#define __NR_N32_Linux_syscalls 316
#endif /* _UAPI_ASM_UNISTD_H */

1
arch/mips/kernel/scall32-o32.S
View File

@ -578,3 +578,4 @@ EXPORT(sys_call_table)
PTR sys_sched_setattr
PTR sys_sched_getattr /* 4350 */
PTR sys_renameat2
PTR sys_seccomp

1
arch/mips/kernel/scall64-64.S
View File

@ -431,4 +431,5 @@ EXPORT(sys_call_table)
PTR sys_sched_setattr
PTR sys_sched_getattr /* 5310 */
PTR sys_renameat2
PTR sys_seccomp
.size sys_call_table,.-sys_call_table

1
arch/mips/kernel/scall64-n32.S
View File

@ -424,4 +424,5 @@ EXPORT(sysn32_call_table)
PTR sys_sched_setattr
PTR sys_sched_getattr
PTR sys_renameat2 /* 6315 */
PTR sys_seccomp
.size sysn32_call_table,.-sysn32_call_table

1
arch/mips/kernel/scall64-o32.S
View File

@ -557,4 +557,5 @@ EXPORT(sys32_call_table)
PTR sys_sched_setattr
PTR sys_sched_getattr /* 4350 */
PTR sys_renameat2
PTR sys_seccomp
.size sys32_call_table,.-sys32_call_table

1
arch/x86/syscalls/syscall_32.tbl
View File

@ -360,3 +360,4 @@
351 i386 sched_setattr sys_sched_setattr
352 i386 sched_getattr sys_sched_getattr
353 i386 renameat2 sys_renameat2
354 i386 seccomp sys_seccomp

1
arch/x86/syscalls/syscall_64.tbl
View File

@ -323,6 +323,7 @@
314 common sched_setattr sys_sched_setattr
315 common sched_getattr sys_sched_getattr
316 common renameat2 sys_renameat2
317 common seccomp sys_seccomp
#
# x32-specific system call numbers start at 512 to avoid cache impact

6
fs/exec.c
View File

@ -1216,7 +1216,7 @@ EXPORT_SYMBOL(install_exec_creds);
/*
* determine how safe it is to execute the proposed program
* - the caller must hold ->cred_guard_mutex to protect against
* PTRACE_ATTACH
* PTRACE_ATTACH or seccomp thread-sync
*/
static void check_unsafe_exec(struct linux_binprm *bprm)
{
@ -1234,7 +1234,7 @@ 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;
@ -1272,7 +1272,7 @@ 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? */

18
include/linux/sched.h
View File

@ -1307,13 +1307,12 @@ 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;
unsigned long atomic_flags; /* Flags needing atomic access. */
pid_t pid;
pid_t tgid;
@ -1967,6 +1966,19 @@ static inline void memalloc_noio_restore(unsigned int flags)
current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
}
/* Per-process atomic flags. */
#define PFA_NO_NEW_PRIVS 0x00000001 /* May not gain new privileges. */
static inline bool task_no_new_privs(struct task_struct *p)
{
return test_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags);
}
static inline void task_set_no_new_privs(struct task_struct *p)
{
set_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags);
}
/*
* task->jobctl flags
*/

8
include/linux/seccomp.h
View File

@ -3,6 +3,8 @@
#include <uapi/linux/seccomp.h>
#define SECCOMP_FILTER_FLAG_MASK (SECCOMP_FILTER_FLAG_TSYNC)
#ifdef CONFIG_SECCOMP
#include <linux/thread_info.h>
@ -14,11 +16,11 @@ struct seccomp_filter;
*
* @mode: indicates one of the valid values above for controlled
* system calls available to a process.
* @filter: The metadata and ruleset for determining what system calls
* are allowed for a task.
* @filter: must always point to a valid seccomp-filter or NULL as it is
* accessed without locking during system call entry.
*
* @filter must only be accessed from the context of current as there
* is no locking.
* is no read locking.
*/
struct seccomp {
int mode;

2
include/linux/syscalls.h
View File

@ -866,4 +866,6 @@ asmlinkage long sys_process_vm_writev(pid_t pid,
asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type,
unsigned long idx1, unsigned long idx2);
asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags);
asmlinkage long sys_seccomp(unsigned int op, unsigned int flags,
const char __user *uargs);
#endif

4
include/uapi/asm-generic/unistd.h
View File

@ -699,9 +699,11 @@ __SYSCALL(__NR_sched_setattr, sys_sched_setattr)
__SYSCALL(__NR_sched_getattr, sys_sched_getattr)
#define __NR_renameat2 276
__SYSCALL(__NR_renameat2, sys_renameat2)
#define __NR_seccomp 277
__SYSCALL(__NR_seccomp, sys_seccomp)
#undef __NR_syscalls
#define __NR_syscalls 277
#define __NR_syscalls 278
/*
* All syscalls below here should go away really,

7
include/uapi/linux/seccomp.h
View File

@ -10,6 +10,13 @@
#define SECCOMP_MODE_STRICT 1 /* uses hard-coded filter. */
#define SECCOMP_MODE_FILTER 2 /* uses user-supplied filter. */
/* Valid operations for seccomp syscall. */
#define SECCOMP_SET_MODE_STRICT 0
#define SECCOMP_SET_MODE_FILTER 1
/* Valid flags for SECCOMP_SET_MODE_FILTER */
#define SECCOMP_FILTER_FLAG_TSYNC 1
/*
* All BPF programs must return a 32-bit value.
* The bottom 16-bits are for optional return data.

49
kernel/fork.c
View File

@ -315,6 +315,15 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
goto free_ti;
tsk->stack = ti;
#ifdef CONFIG_SECCOMP
/*
* We must handle setting up seccomp filters once we're under
* the sighand lock in case orig has changed between now and
* then. Until then, filter must be NULL to avoid messing up
* the usage counts on the error path calling free_task.
*/
tsk->seccomp.filter = NULL;
#endif
setup_thread_stack(tsk, orig);
clear_user_return_notifier(tsk);
@ -1081,6 +1090,39 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
return 0;
}
static void copy_seccomp(struct task_struct *p)
{
#ifdef CONFIG_SECCOMP
/*
* Must be called with sighand->lock held, which is common to
* all threads in the group. Holding cred_guard_mutex is not
* needed because this new task is not yet running and cannot
* be racing exec.
*/
BUG_ON(!spin_is_locked(&current->sighand->siglock));
/* Ref-count the new filter user, and assign it. */
get_seccomp_filter(current);
p->seccomp = current->seccomp;
/*
* Explicitly enable no_new_privs here in case it got set
* between the task_struct being duplicated and holding the
* sighand lock. The seccomp state and nnp must be in sync.
*/
if (task_no_new_privs(current))
task_set_no_new_privs(p);
/*
* If the parent gained a seccomp mode after copying thread
* flags and between before we held the sighand lock, we have
* to manually enable the seccomp thread flag here.
*/
if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
set_tsk_thread_flag(p, TIF_SECCOMP);
#endif
}
SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
{
current->clear_child_tid = tidptr;
@ -1196,7 +1238,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
goto fork_out;
ftrace_graph_init_task(p);
get_seccomp_filter(p);
rt_mutex_init_task(p);
@ -1436,6 +1477,12 @@ static struct task_struct *copy_process(unsigned long clone_flags,
spin_lock(&current->sighand->siglock);
/*
* Copy seccomp details explicitly here, in case they were changed
* before holding sighand lock.
*/
copy_seccomp(p);
/*
* Process group and session signals need to be delivered to just the
* parent before the fork or both the parent and the child after the

414
kernel/seccomp.c
View File

@ -18,15 +18,17 @@
#include <linux/compat.h>
#include <linux/sched.h>
#include <linux/seccomp.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
/* #define SECCOMP_DEBUG 1 */
#ifdef CONFIG_SECCOMP_FILTER
#include <asm/syscall.h>
#include <linux/filter.h>
#include <linux/pid.h>
#include <linux/ptrace.h>
#include <linux/security.h>
#include <linux/slab.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>
@ -172,21 +174,24 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
*/
static u32 seccomp_run_filters(int syscall)
{
struct seccomp_filter *f;
struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
struct seccomp_data sd;
u32 ret = SECCOMP_RET_ALLOW;
/* Ensure unexpected behavior doesn't result in failing open. */
if (WARN_ON(current->seccomp.filter == NULL))
if (unlikely(WARN_ON(f == NULL)))
return SECCOMP_RET_KILL;
/* Make sure cross-thread synced filter points somewhere sane. */
smp_read_barrier_depends();
populate_seccomp_data(&sd);
/*
* All filters in the list are evaluated and the lowest BPF return
* value always takes priority (ignoring the DATA).
*/
for (f = current->seccomp.filter; f; f = f->prev) {
for (; f; f = f->prev) {
u32 cur_ret = SK_RUN_FILTER(f->prog, (void *)&sd);
if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
@ -194,29 +199,159 @@ static u32 seccomp_run_filters(int syscall)
}
return ret;
}
#endif /* CONFIG_SECCOMP_FILTER */
static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
{
BUG_ON(!spin_is_locked(&current->sighand->siglock));
if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
return false;
return true;
}
static inline void seccomp_assign_mode(struct task_struct *task,
unsigned long seccomp_mode)
{
BUG_ON(!spin_is_locked(&task->sighand->siglock));
task->seccomp.mode = seccomp_mode;
/*
* Make sure TIF_SECCOMP cannot be set before the mode (and
* filter) is set.
*/
smp_mb__before_atomic();
set_tsk_thread_flag(task, TIF_SECCOMP);
}
#ifdef CONFIG_SECCOMP_FILTER
/* Returns 1 if the parent is an ancestor of the child. */
static int is_ancestor(struct seccomp_filter *parent,
struct seccomp_filter *child)
{
/* NULL is the root ancestor. */
if (parent == NULL)
return 1;
for (; child; child = child->prev)
if (child == parent)
return 1;
return 0;
}
/**
* seccomp_attach_filter: Attaches a seccomp filter to current.
* seccomp_can_sync_threads: checks if all threads can be synchronized
*
* Expects sighand and cred_guard_mutex locks to be held.
*
* Returns 0 on success, -ve on error, or the pid of a thread which was
* either not in the correct seccomp mode or it did not have an ancestral
* seccomp filter.
*/
static inline pid_t seccomp_can_sync_threads(void)
{
struct task_struct *thread, *caller;
BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
BUG_ON(!spin_is_locked(&current->sighand->siglock));
/* Validate all threads being eligible for synchronization. */
caller = current;
for_each_thread(caller, thread) {
pid_t failed;
/* Skip current, since it is initiating the sync. */
if (thread == caller)
continue;
if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
(thread->seccomp.mode == SECCOMP_MODE_FILTER &&
is_ancestor(thread->seccomp.filter,
caller->seccomp.filter)))
continue;
/* Return the first thread that cannot be synchronized. */
failed = task_pid_vnr(thread);
/* If the pid cannot be resolved, then return -ESRCH */
if (unlikely(WARN_ON(failed == 0)))
failed = -ESRCH;
return failed;
}
return 0;
}
/**
* seccomp_sync_threads: sets all threads to use current's filter
*
* Expects sighand and cred_guard_mutex locks to be held, and for
* seccomp_can_sync_threads() to have returned success already
* without dropping the locks.
*
*/
static inline void seccomp_sync_threads(void)
{
struct task_struct *thread, *caller;
BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
BUG_ON(!spin_is_locked(&current->sighand->siglock));
/* Synchronize all threads. */
caller = current;
for_each_thread(caller, thread) {
/* Skip current, since it needs no changes. */
if (thread == caller)
continue;
/* Get a task reference for the new leaf node. */
get_seccomp_filter(caller);
/*
* Drop the task reference to the shared ancestor since
* current's path will hold a reference. (This also
* allows a put before the assignment.)
*/
put_seccomp_filter(thread);
smp_store_release(&thread->seccomp.filter,
caller->seccomp.filter);
/*
* Opt the other thread into seccomp if needed.
* As threads are considered to be trust-realm
* equivalent (see ptrace_may_access), it is safe to
* allow one thread to transition the other.
*/
if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) {
/*
* Don't let an unprivileged task work around
* the no_new_privs restriction by creating
* a thread that sets it up, enters seccomp,
* then dies.
*/
if (task_no_new_privs(caller))
task_set_no_new_privs(thread);
seccomp_assign_mode(thread, SECCOMP_MODE_FILTER);
}
}
}
/**
* seccomp_prepare_filter: Prepares a seccomp filter for use.
* @fprog: BPF program to install
*
* Returns 0 on success or an errno on failure.
* Returns filter on success or an ERR_PTR on failure.
*/
static long seccomp_attach_filter(struct sock_fprog *fprog)
static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
{
struct seccomp_filter *filter;
unsigned long fp_size = fprog->len * sizeof(struct sock_filter);
unsigned long total_insns = fprog->len;
unsigned long fp_size;
struct sock_filter *fp;
int new_len;
long ret;
if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
return -EINVAL;
for (filter = current->seccomp.filter; filter; filter = filter->prev)
total_insns += filter->prog->len + 4; /* include a 4 instr penalty */
if (total_insns > MAX_INSNS_PER_PATH)
return -ENOMEM;
return ERR_PTR(-EINVAL);
BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
fp_size = fprog->len * sizeof(struct sock_filter);
/*
* Installing a seccomp filter requires that the task has
@ -224,14 +359,14 @@ static long seccomp_attach_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 -EACCES;
return ERR_PTR(-EACCES);
fp = kzalloc(fp_size, GFP_KERNEL|__GFP_NOWARN);
if (!fp)
return -ENOMEM;
return ERR_PTR(-ENOMEM);
/* Copy the instructions from fprog. */
ret = -EFAULT;
@ -275,13 +410,7 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
sk_filter_select_runtime(filter->prog);
/*
* If there is an existing filter, make it the prev and don't drop its
* task reference.
*/
filter->prev = current->seccomp.filter;
current->seccomp.filter = filter;
return 0;
return filter;
free_filter_prog:
kfree(filter->prog);
@ -289,19 +418,20 @@ free_filter:
kfree(filter);
free_prog:
kfree(fp);
return ret;
return ERR_PTR(ret);
}
/**
* seccomp_attach_user_filter - attaches a user-supplied sock_fprog
* seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
* @user_filter: pointer to the user data containing a sock_fprog.
*
* Returns 0 on success and non-zero otherwise.
*/
static long seccomp_attach_user_filter(char __user *user_filter)
static struct seccomp_filter *
seccomp_prepare_user_filter(const char __user *user_filter)
{
struct sock_fprog fprog;
long ret = -EFAULT;
struct seccomp_filter *filter = ERR_PTR(-EFAULT);
#ifdef CONFIG_COMPAT
if (is_compat_task()) {
@ -314,9 +444,56 @@ static long seccomp_attach_user_filter(char __user *user_filter)
#endif
if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
goto out;
ret = seccomp_attach_filter(&fprog);
filter = seccomp_prepare_filter(&fprog);
out:
return ret;
return filter;
}
/**
* seccomp_attach_filter: validate and attach filter
* @flags: flags to change filter behavior
* @filter: seccomp filter to add to the current process
*
* Caller must be holding current->sighand->siglock lock.
*
* Returns 0 on success, -ve on error.
*/
static long seccomp_attach_filter(unsigned int flags,
struct seccomp_filter *filter)
{
unsigned long total_insns;
struct seccomp_filter *walker;
BUG_ON(!spin_is_locked(&current->sighand->siglock));
/* Validate resulting filter length. */
total_insns = filter->prog->len;
for (walker = current->seccomp.filter; walker; walker = walker->prev)
total_insns += walker->prog->len + 4; /* 4 instr penalty */
if (total_insns > MAX_INSNS_PER_PATH)
return -ENOMEM;
/* If thread sync has been requested, check that it is possible. */
if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
int ret;
ret = seccomp_can_sync_threads();
if (ret)
return ret;
}
/*
* If there is an existing filter, make it the prev and don't drop its
* task reference.
*/
filter->prev = current->seccomp.filter;
current->seccomp.filter = filter;
/* Now that the new filter is in place, synchronize to all threads. */
if (flags & SECCOMP_FILTER_FLAG_TSYNC)
seccomp_sync_threads();
return 0;
}
/* get_seccomp_filter - increments the reference count of the filter on @tsk */
@ -329,6 +506,14 @@ void get_seccomp_filter(struct task_struct *tsk)
atomic_inc(&orig->usage);
}
static inline void seccomp_filter_free(struct seccomp_filter *filter)
{
if (filter) {
sk_filter_free(filter->prog);
kfree(filter);
}
}
/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
void put_seccomp_filter(struct task_struct *tsk)
{
@ -337,8 +522,7 @@ void put_seccomp_filter(struct task_struct *tsk)
while (orig && atomic_dec_and_test(&orig->usage)) {
struct seccomp_filter *freeme = orig;
orig = orig->prev;
sk_filter_free(freeme->prog);
kfree(freeme);
seccomp_filter_free(freeme);
}
}
@ -382,12 +566,17 @@ static int mode1_syscalls_32[] = {
int __secure_computing(int this_syscall)
{
int mode = current->seccomp.mode;
int exit_sig = 0;
int *syscall;
u32 ret;
switch (mode) {
/*
* Make sure that any changes to mode from another thread have
* been seen after TIF_SECCOMP was seen.
*/
rmb();
switch (current->seccomp.mode) {
case SECCOMP_MODE_STRICT:
syscall = mode1_syscalls;
#ifdef CONFIG_COMPAT
@ -473,47 +662,152 @@ long prctl_get_seccomp(void)
}
/**
* prctl_set_seccomp: configures current->seccomp.mode
* @seccomp_mode: requested mode to use
* @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
*
* This function may be called repeatedly with a @seccomp_mode of
* SECCOMP_MODE_FILTER to install additional filters. Every filter
* successfully installed will be evaluated (in reverse order) for each system
* call the task makes.
* seccomp_set_mode_strict: internal function for setting strict seccomp
*
* Once current->seccomp.mode is non-zero, it may not be changed.
*
* Returns 0 on success or -EINVAL on failure.
*/
long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
static long seccomp_set_mode_strict(void)
{
const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
long ret = -EINVAL;
if (current->seccomp.mode &&
current->seccomp.mode != seccomp_mode)
spin_lock_irq(&current->sighand->siglock);
if (!seccomp_may_assign_mode(seccomp_mode))
goto out;
#ifdef TIF_NOTSC
disable_TSC();
#endif
seccomp_assign_mode(current, seccomp_mode);
ret = 0;
out:
spin_unlock_irq(&current->sighand->siglock);
return ret;
}
#ifdef CONFIG_SECCOMP_FILTER
/**
* seccomp_set_mode_filter: internal function for setting seccomp filter
* @flags: flags to change filter behavior
* @filter: struct sock_fprog containing filter
*
* This function may be called repeatedly to install additional filters.
* Every filter successfully installed will be evaluated (in reverse order)
* for each system call the task makes.
*
* Once current->seccomp.mode is non-zero, it may not be changed.
*
* Returns 0 on success or -EINVAL on failure.
*/
static long seccomp_set_mode_filter(unsigned int flags,
const char __user *filter)
{
const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
struct seccomp_filter *prepared = NULL;
long ret = -EINVAL;
/* Validate flags. */
if (flags & ~SECCOMP_FILTER_FLAG_MASK)
return -EINVAL;
/* Prepare the new filter before holding any locks. */
prepared = seccomp_prepare_user_filter(filter);
if (IS_ERR(prepared))
return PTR_ERR(prepared);
/*
* Make sure we cannot change seccomp or nnp state via TSYNC
* while another thread is in the middle of calling exec.
*/
if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
mutex_lock_killable(&current->signal->cred_guard_mutex))
goto out_free;
spin_lock_irq(&current->sighand->siglock);
if (!seccomp_may_assign_mode(seccomp_mode))
goto out;
ret = seccomp_attach_filter(flags, prepared);
if (ret)
goto out;
/* Do not free the successfully attached filter. */
prepared = NULL;
seccomp_assign_mode(current, seccomp_mode);
out:
spin_unlock_irq(&current->sighand->siglock);
if (flags & SECCOMP_FILTER_FLAG_TSYNC)
mutex_unlock(&current->signal->cred_guard_mutex);
out_free:
seccomp_filter_free(prepared);
return ret;
}
#else
static inline long seccomp_set_mode_filter(unsigned int flags,
const char __user *filter)
{
return -EINVAL;
}
#endif
/* Common entry point for both prctl and syscall. */
static long do_seccomp(unsigned int op, unsigned int flags,
const char __user *uargs)
{
switch (op) {
case SECCOMP_SET_MODE_STRICT:
if (flags != 0 || uargs != NULL)
return -EINVAL;
return seccomp_set_mode_strict();
case SECCOMP_SET_MODE_FILTER:
return seccomp_set_mode_filter(flags, uargs);
default:
return -EINVAL;
}
}
SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
const char __user *, uargs)
{
return do_seccomp(op, flags, uargs);
}
/**
* prctl_set_seccomp: configures current->seccomp.mode
* @seccomp_mode: requested mode to use
* @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
*
* Returns 0 on success or -EINVAL on failure.
*/
long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
{
unsigned int op;
char __user *uargs;
switch (seccomp_mode) {
case SECCOMP_MODE_STRICT:
ret = 0;
#ifdef TIF_NOTSC
disable_TSC();
#endif
op = SECCOMP_SET_MODE_STRICT;
/*
* Setting strict mode through prctl always ignored filter,
* so make sure it is always NULL here to pass the internal
* check in do_seccomp().
*/
uargs = NULL;
break;
#ifdef CONFIG_SECCOMP_FILTER
case SECCOMP_MODE_FILTER:
ret = seccomp_attach_user_filter(filter);
if (ret)
goto out;
op = SECCOMP_SET_MODE_FILTER;
uargs = filter;
break;
#endif
default:
goto out;
return -EINVAL;
}
current->seccomp.mode = seccomp_mode;
set_thread_flag(TIF_SECCOMP);
out:
return ret;
/* prctl interface doesn't have flags, so they are always zero. */
return do_seccomp(op, 0, uargs);
}

4
kernel/sys.c
View File

@ -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;

3
kernel/sys_ni.c
View File

@ -213,3 +213,6 @@ cond_syscall(compat_sys_open_by_handle_at);
/* compare kernel pointers */
cond_syscall(sys_kcmp);
/* operate on Secure Computing state */
cond_syscall(sys_seccomp);

4
security/apparmor/domain.c
View File

@ -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;
}