diff options
Diffstat (limited to 'kernel/sys.c')
| -rw-r--r-- | kernel/sys.c | 202 |
1 files changed, 158 insertions, 44 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index e83ddbb..e9ad444 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1236,15 +1236,14 @@ SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len) SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim) { - if (resource >= RLIM_NLIMITS) - return -EINVAL; - else { - struct rlimit value; - task_lock(current->group_leader); - value = current->signal->rlim[resource]; - task_unlock(current->group_leader); - return copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0; - } + struct rlimit value; + int ret; + + ret = do_prlimit(current, resource, NULL, &value); + if (!ret) + ret = copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0; + + return ret; } #ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT @@ -1272,44 +1271,89 @@ SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource, #endif -SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim) +static inline bool rlim64_is_infinity(__u64 rlim64) { - struct rlimit new_rlim, *old_rlim; - int retval; +#if BITS_PER_LONG < 64 + return rlim64 >= ULONG_MAX; +#else + return rlim64 == RLIM64_INFINITY; +#endif +} + +static void rlim_to_rlim64(const struct rlimit *rlim, struct rlimit64 *rlim64) +{ + if (rlim->rlim_cur == RLIM_INFINITY) + rlim64->rlim_cur = RLIM64_INFINITY; + else + rlim64->rlim_cur = rlim->rlim_cur; + if (rlim->rlim_max == RLIM_INFINITY) + rlim64->rlim_max = RLIM64_INFINITY; + else + rlim64->rlim_max = rlim->rlim_max; +} + +static void rlim64_to_rlim(const struct rlimit64 *rlim64, struct rlimit *rlim) +{ + if (rlim64_is_infinity(rlim64->rlim_cur)) + rlim->rlim_cur = RLIM_INFINITY; + else + rlim->rlim_cur = (unsigned long)rlim64->rlim_cur; + if (rlim64_is_infinity(rlim64->rlim_max)) + rlim->rlim_max = RLIM_INFINITY; + else + rlim->rlim_max = (unsigned long)rlim64->rlim_max; +} + +/* make sure you are allowed to change @tsk limits before calling this */ +int do_prlimit(struct task_struct *tsk, unsigned int resource, + struct rlimit *new_rlim, struct rlimit *old_rlim) +{ + struct rlimit *rlim; + int retval = 0; if (resource >= RLIM_NLIMITS) return -EINVAL; - if (copy_from_user(&new_rlim, rlim, sizeof(*rlim))) - return -EFAULT; - if (new_rlim.rlim_cur > new_rlim.rlim_max) - return -EINVAL; - old_rlim = current->signal->rlim + resource; - if ((new_rlim.rlim_max > old_rlim->rlim_max) && - !capable(CAP_SYS_RESOURCE)) - return -EPERM; - if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open) - return -EPERM; - - retval = security_task_setrlimit(resource, &new_rlim); - if (retval) - return retval; - - if (resource == RLIMIT_CPU && new_rlim.rlim_cur == 0) { - /* - * The caller is asking for an immediate RLIMIT_CPU - * expiry. But we use the zero value to mean "it was - * never set". So let's cheat and make it one second - * instead - */ - new_rlim.rlim_cur = 1; + if (new_rlim) { + if (new_rlim->rlim_cur > new_rlim->rlim_max) + return -EINVAL; + if (resource == RLIMIT_NOFILE && + new_rlim->rlim_max > sysctl_nr_open) + return -EPERM; } - task_lock(current->group_leader); - *old_rlim = new_rlim; - task_unlock(current->group_leader); - - if (resource != RLIMIT_CPU) + /* protect tsk->signal and tsk->sighand from disappearing */ + read_lock(&tasklist_lock); + if (!tsk->sighand) { + retval = -ESRCH; goto out; + } + + rlim = tsk->signal->rlim + resource; + task_lock(tsk->group_leader); + if (new_rlim) { + if (new_rlim->rlim_max > rlim->rlim_max && + !capable(CAP_SYS_RESOURCE)) + retval = -EPERM; + if (!retval) + retval = security_task_setrlimit(tsk->group_leader, + resource, new_rlim); + if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) { + /* + * The caller is asking for an immediate RLIMIT_CPU + * expiry. But we use the zero value to mean "it was + * never set". So let's cheat and make it one second + * instead + */ + new_rlim->rlim_cur = 1; + } + } + if (!retval) { + if (old_rlim) + *old_rlim = *rlim; + if (new_rlim) + *rlim = *new_rlim; + } + task_unlock(tsk->group_leader); /* * RLIMIT_CPU handling. Note that the kernel fails to return an error @@ -1317,14 +1361,84 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim) * very long-standing error, and fixing it now risks breakage of * applications, so we live with it */ - if (new_rlim.rlim_cur == RLIM_INFINITY) - goto out; - - update_rlimit_cpu(new_rlim.rlim_cur); + if (!retval && new_rlim && resource == RLIMIT_CPU && + new_rlim->rlim_cur != RLIM_INFINITY) + update_rlimit_cpu(tsk, new_rlim->rlim_cur); out: + read_unlock(&tasklist_lock); + return retval; +} + +/* rcu lock must be held */ +static int check_prlimit_permission(struct task_struct *task) +{ + const struct cred *cred = current_cred(), *tcred; + + tcred = __task_cred(task); + if ((cred->uid != tcred->euid || + cred->uid != tcred->suid || + cred->uid != tcred->uid || + cred->gid != tcred->egid || + cred->gid != tcred->sgid || + cred->gid != tcred->gid) && + !capable(CAP_SYS_RESOURCE)) { + return -EPERM; + } + return 0; } +SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource, + const struct rlimit64 __user *, new_rlim, + struct rlimit64 __user *, old_rlim) +{ + struct rlimit64 old64, new64; + struct rlimit old, new; + struct task_struct *tsk; + int ret; + + if (new_rlim) { + if (copy_from_user(&new64, new_rlim, sizeof(new64))) + return -EFAULT; + rlim64_to_rlim(&new64, &new); + } + + rcu_read_lock(); + tsk = pid ? find_task_by_vpid(pid) : current; + if (!tsk) { + rcu_read_unlock(); + return -ESRCH; + } + ret = check_prlimit_permission(tsk); + if (ret) { + rcu_read_unlock(); + return ret; + } + get_task_struct(tsk); + rcu_read_unlock(); + + ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL, + old_rlim ? &old : NULL); + + if (!ret && old_rlim) { + rlim_to_rlim64(&old, &old64); + if (copy_to_user(old_rlim, &old64, sizeof(old64))) + ret = -EFAULT; + } + + put_task_struct(tsk); + return ret; +} + +SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim) +{ + struct rlimit new_rlim; + + if (copy_from_user(&new_rlim, rlim, sizeof(*rlim))) + return -EFAULT; + return do_prlimit(current, resource, &new_rlim, NULL); +} + /* * It would make sense to put struct rusage in the task_struct, * except that would make the task_struct be *really big*. 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