diff options
| author | Akinobu Mita <akinobu.mita@gmail.com> | 2017-05-09 09:47:55 +1000 |
|---|---|---|
| committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2017-05-09 13:09:16 +1000 |
| commit | 904b217260ee31e9d1e073515c3ba00e0e17399a (patch) | |
| tree | c3eae13373bd4cfb756fd8c431c8d9a42c729fda | |
| parent | 1d4f895858b21464ee6ae628fae641d56a0a7ceb (diff) | |
fault-inject: simplify access check for fail-nth
The fail-nth file is created with 0666 and the access is permitted if
and only if the task is current.
This file is owned by the currnet user. So we can create it with 0644 and
allow the owner to write it. This enables to watch the status of
task->fail_nth from another processes.
Link: http://lkml.kernel.org/r/1491490561-10485-5-git-send-email-akinobu.mita@gmail.com
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | fs/proc/base.c | 22 |
1 files changed, 8 insertions, 14 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 9d14215db2e7..14e7b7397d49 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1366,16 +1366,16 @@ static ssize_t proc_fail_nth_write(struct file *file, const char __user *buf, int err; unsigned int n; + err = kstrtoint_from_user(buf, count, 0, &n); + if (err) + return err; + task = get_proc_task(file_inode(file)); if (!task) return -ESRCH; + task->fail_nth = n; put_task_struct(task); - if (task != current) - return -EPERM; - err = kstrtouint_from_user(buf, count, 0, &n); - if (err) - return err; - current->fail_nth = n; + return count; } @@ -1389,11 +1389,9 @@ static ssize_t proc_fail_nth_read(struct file *file, char __user *buf, task = get_proc_task(file_inode(file)); if (!task) return -ESRCH; - put_task_struct(task); - if (task != current) - return -EPERM; len = snprintf(numbuf, sizeof(numbuf), "%u\n", task->fail_nth); len = simple_read_from_buffer(buf, count, ppos, numbuf, len); + put_task_struct(task); return len; } @@ -3358,11 +3356,7 @@ static const struct pid_entry tid_base_stuff[] = { #endif #ifdef CONFIG_FAULT_INJECTION REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations), - /* - * Operations on the file check that the task is current, - * so we create it with 0666 to support testing under unprivileged user. - */ - REG("fail-nth", 0666, proc_fail_nth_operations), + REG("fail-nth", 0644, proc_fail_nth_operations), #endif #ifdef CONFIG_TASK_IO_ACCOUNTING ONE("io", S_IRUSR, proc_tid_io_accounting), |