* [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline
@ 2014-07-16 21:32 Alexey Dobriyan
2014-07-17 22:53 ` Andrew Morton
0 siblings, 1 reply; 4+ messages in thread
From: Alexey Dobriyan @ 2014-07-16 21:32 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel
Convert /proc/$PID/cmdline to seq_file interface.
XXX
This one must be buggy.
seq_file buffer is adjustable, so userspace can execute itself
with huge command line (which can be arbitrarily long now), then read 1 byte.
Voila, whole command line now is in kmalloced/vmalloced memory.
Imposing limit is trivial but equally lame to current PAGE_SIZE limit.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/proc/base.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -200,9 +200,17 @@ static int proc_root_link(struct dentry *dentry, struct path *path)
return result;
}
-static int proc_pid_cmdline(struct task_struct *task, char *buffer)
+static int proc_pid_cmdline(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *task)
{
- return get_cmdline(task, buffer, PAGE_SIZE);
+ /*
+ * Rely on struct seq_operations::show() being called once
+ * per internal buffer allocation. See single_open(), traverse().
+ *
+ * Rely on internal buffer autoexpansion if it was entirely filled.
+ */
+ m->count += get_cmdline(task, m->buf, m->size);
+ return 0;
}
static int proc_pid_auxv(struct seq_file *m, struct pid_namespace *ns,
@@ -2567,7 +2575,7 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
ONE("syscall", S_IRUSR, proc_pid_syscall),
#endif
- INF("cmdline", S_IRUGO, proc_pid_cmdline),
+ ONE("cmdline", S_IRUGO, proc_pid_cmdline),
ONE("stat", S_IRUGO, proc_tgid_stat),
ONE("statm", S_IRUGO, proc_pid_statm),
REG("maps", S_IRUGO, proc_pid_maps_operations),
@@ -2903,7 +2911,7 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
ONE("syscall", S_IRUSR, proc_pid_syscall),
#endif
- INF("cmdline", S_IRUGO, proc_pid_cmdline),
+ ONE("cmdline", S_IRUGO, proc_pid_cmdline),
ONE("stat", S_IRUGO, proc_tid_stat),
ONE("statm", S_IRUGO, proc_pid_statm),
REG("maps", S_IRUGO, proc_tid_maps_operations),
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline
2014-07-16 21:32 [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline Alexey Dobriyan
@ 2014-07-17 22:53 ` Andrew Morton
2014-07-18 20:10 ` Alexey Dobriyan
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2014-07-17 22:53 UTC (permalink / raw)
To: Alexey Dobriyan; +Cc: linux-kernel
On Thu, 17 Jul 2014 00:32:47 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:
> Convert /proc/$PID/cmdline to seq_file interface.
>
> XXX
Unsure what XXX signifies.
> This one must be buggy.
>
> seq_file buffer is adjustable, so userspace can execute itself
> with huge command line (which can be arbitrarily long now), then read 1 byte.
>
> Voila, whole command line now is in kmalloced/vmalloced memory.
>
> Imposing limit is trivial but equally lame to current PAGE_SIZE limit.
Confused. Why send the patch if you don't like it?
Why not go ahead and impose the PAGE_SIZE limit?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline
2014-07-17 22:53 ` Andrew Morton
@ 2014-07-18 20:10 ` Alexey Dobriyan
2014-07-18 20:12 ` [PATCH v2 04/10] proc: convert /proc/$PID/cmdline to seq_file interface Alexey Dobriyan
0 siblings, 1 reply; 4+ messages in thread
From: Alexey Dobriyan @ 2014-07-18 20:10 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel
On Thu, Jul 17, 2014 at 03:53:46PM -0700, Andrew Morton wrote:
> On Thu, 17 Jul 2014 00:32:47 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:
>
> > Convert /proc/$PID/cmdline to seq_file interface.
> >
> > XXX
>
> Unsure what XXX signifies.
>
> > This one must be buggy.
> >
> > seq_file buffer is adjustable, so userspace can execute itself
> > with huge command line (which can be arbitrarily long now), then read 1 byte.
> >
> > Voila, whole command line now is in kmalloced/vmalloced memory.
> >
> > Imposing limit is trivial but equally lame to current PAGE_SIZE limit.
>
> Confused. Why send the patch if you don't like it?
>
> Why not go ahead and impose the PAGE_SIZE limit?
I thought someone smarter than me would suggest what to do.
Please replace with v2.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2 04/10] proc: convert /proc/$PID/cmdline to seq_file interface
2014-07-18 20:10 ` Alexey Dobriyan
@ 2014-07-18 20:12 ` Alexey Dobriyan
0 siblings, 0 replies; 4+ messages in thread
From: Alexey Dobriyan @ 2014-07-18 20:12 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/proc/base.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -200,9 +200,16 @@ static int proc_root_link(struct dentry *dentry, struct path *path)
return result;
}
-static int proc_pid_cmdline(struct task_struct *task, char *buffer)
+static int proc_pid_cmdline(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *task)
{
- return get_cmdline(task, buffer, PAGE_SIZE);
+ /*
+ * Rely on struct seq_operations::show() being called once
+ * per internal buffer allocation. See single_open(), traverse().
+ */
+ BUG_ON(m->size < PAGE_SIZE);
+ m->count += get_cmdline(task, m->buf, PAGE_SIZE);
+ return 0;
}
static int proc_pid_auxv(struct seq_file *m, struct pid_namespace *ns,
@@ -2567,7 +2574,7 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
ONE("syscall", S_IRUSR, proc_pid_syscall),
#endif
- INF("cmdline", S_IRUGO, proc_pid_cmdline),
+ ONE("cmdline", S_IRUGO, proc_pid_cmdline),
ONE("stat", S_IRUGO, proc_tgid_stat),
ONE("statm", S_IRUGO, proc_pid_statm),
REG("maps", S_IRUGO, proc_pid_maps_operations),
@@ -2903,7 +2910,7 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
ONE("syscall", S_IRUSR, proc_pid_syscall),
#endif
- INF("cmdline", S_IRUGO, proc_pid_cmdline),
+ ONE("cmdline", S_IRUGO, proc_pid_cmdline),
ONE("stat", S_IRUGO, proc_tid_stat),
ONE("statm", S_IRUGO, proc_pid_statm),
REG("maps", S_IRUGO, proc_tid_maps_operations),
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-07-18 20:12 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2014-07-16 21:32 [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline Alexey Dobriyan
2014-07-17 22:53 ` Andrew Morton
2014-07-18 20:10 ` Alexey Dobriyan
2014-07-18 20:12 ` [PATCH v2 04/10] proc: convert /proc/$PID/cmdline to seq_file interface Alexey Dobriyan
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