The "PAGE_SIZE - 2 - size" calculation in legacy_parse_param() is an
unsigned type so a large value of "size" results in a high positive
value instead of a negative value as expected.  Fix this by getting rid
of the subtraction.

Signed-off-by: Jamie Hill-Daniel <jamie@hill-daniel.co.uk>
Signed-off-by: William Liu <willsroot@protonmail.com>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Tested-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This patch adds accounting flags to fs_context and legacy_fs_context
allocation sites so that kernel could correctly charge these objects.

We have written a PoC to demonstrate the effect of the missing-charging
bugs.  The PoC takes around 1,200MB unaccounted memory, while it is
charged for only 362MB memory usage.  We evaluate the PoC on QEMU x86_64
v5.2.90 + Linux kernel v5.10.19 + Debian buster.  All the limitations
including ulimits and sysctl variables are set as default.  Specifically,
the hard NOFILE limit and nr_open in sysctl are both 1,048,576.

/*------------------------- POC code ----------------------------*/

#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/file.h>
#include <time.h>
#include <sys/wait.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include <sched.h>
#include <fcntl.h>
#include <linux/mount.h>

#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \
                        } while (0)

#define STACK_SIZE (8 * 1024)
#ifndef __NR_fsopen
#define __NR_fsopen 430
#endif
static inline int fsopen(const char *fs_name, unsigned int flags)
{
        return syscall(__NR_fsopen, fs_name, flags);
}

static char thread_stack[512][STACK_SIZE];

int thread_fn(void* arg)
{
  for (int i = 0; i< 800000; ++i) {
    int fsfd = fsopen("nfs", FSOPEN_CLOEXEC);
    if (fsfd == -1) {
      errExit("fsopen");
    }
  }
  while(1);
  return 0;
}

int main(int argc, char *argv[]) {
  int thread_pid;
  for (int i = 0; i < 1; ++i) {
    thread_pid = clone(thread_fn, thread_stack[i] + STACK_SIZE, \
      SIGCHLD, NULL);
  }
  while(1);
  return 0;
}

/*-------------------------- end --------------------------------*/

Link: https://lkml.kernel.org/r/1626517201-24086-1-git-send-email-nglaive@gmail.com
Signed-off-by: Yutian Yang <nglaive@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <shenwenbo@zju.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add a simple helper that filesystems can use in their parameter parser
to parse the "source" parameter. A few places open-coded this function
and that already caused a bug in the cgroup v1 parser that we fixed.
Let's make it harder to get this wrong by introducing a helper which
performs all necessary checks.

Link: https://syzkaller.appspot.com/bug?id=6312526aba5beae046fdae8f00399f87aab48b12
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Parsing "silent" and clearing SB_SILENT makes zero sense.

Parsing "silent" and setting SB_SILENT would make a bit more sense, but
apparently nobody cares.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Unlike the others, this is _not_ a standard option accepted by mount(8).

In fact SB_POSIXACL is an internal flag, and accepting MS_POSIXACL on the
mount(2) interface is possibly a bug.

The only filesystem that apparently wants to handle the "posixacl" option
is 9p, but it has special handling of that option besides setting
SB_POSIXACL.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Makes little sense to keep this blacklist synced with what mount(8) parses
and what it doesn't.  E.g. it has various forms of "*atime" options, but
not "atime"...

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

... turning it into struct p_log embedded into fs_context.  Initialize
the prefix with fs_type->name, turning fs_parse() into a trivial
inline wrapper for __fs_parse().

This makes fs_parameter_description->name completely unused.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Have the arrays of constant_table self-terminated (by NULL ->name
in the final entry).  Simplifies lookup_constant() and allows to
reuse the search for enum params as well.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>