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pipe, sysctl: drop 'min' parameter from pipe-max-size converter

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Patch series "pipe: buffer limits fixes and cleanups", v2.

This series simplifies the sysctl handler for pipe-max-size and fixes
another set of bugs related to the pipe buffer limits:

- The root user wasn't allowed to exceed the limits when creating new
  pipes.

- There was an off-by-one error when checking the limits, so a limit of
  N was actually treated as N - 1.

- F_SETPIPE_SZ accepted values over UINT_MAX.

- Reading the pipe buffer limits could be racy.

This patch (of 7):

Before validating the given value against pipe_min_size,
do_proc_dopipe_max_size_conv() calls round_pipe_size(), which rounds the
value up to pipe_min_size.  Therefore, the second check against
pipe_min_size is redundant.  Remove it.

Link: http://lkml.kernel.org/r/20180111052902.14409-2-ebiggers3@gmail.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Luis R . Rodriguez" <mcgrof@kernel.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric Biggers 2018-02-06 15:41:45 -08:00 committed by Linus Torvalds
parent e7c52b84fb
commit 4c2e4befb3
3 changed files with 5 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
fs/pipe.c
View File

@ -35,11 +35,6 @@
*/
unsigned int pipe_max_size = 1048576;
/*
* Minimum pipe size, as required by POSIX
*/
unsigned int pipe_min_size = PAGE_SIZE;
/* Maximum allocatable pages per user. Hard limit is unset by default, soft
* matches default values.
*/
@ -1024,8 +1019,9 @@ unsigned int round_pipe_size(unsigned int size)
{
unsigned long nr_pages;
if (size < pipe_min_size)
size = pipe_min_size;
/* Minimum pipe size, as required by POSIX */
if (size < PAGE_SIZE)
size = PAGE_SIZE;
nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (nr_pages == 0)

2
include/linux/pipe_fs_i.h
View File

@ -167,7 +167,7 @@ void pipe_lock(struct pipe_inode_info *);
void pipe_unlock(struct pipe_inode_info *);
void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
extern unsigned int pipe_max_size, pipe_min_size;
extern unsigned int pipe_max_size;
extern unsigned long pipe_user_pages_hard;
extern unsigned long pipe_user_pages_soft;
int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);

15
kernel/sysctl.c
View File

@ -1813,7 +1813,6 @@ static struct ctl_table fs_table[] = {
.maxlen = sizeof(pipe_max_size),
.mode = 0644,
.proc_handler = &pipe_proc_fn,
.extra1 = &pipe_min_size,
},
{
.procname = "pipe-user-pages-hard",
@ -2615,16 +2614,10 @@ int proc_douintvec_minmax(struct ctl_table *table, int write,
do_proc_douintvec_minmax_conv, &param);
}
struct do_proc_dopipe_max_size_conv_param {
unsigned int *min;
};
static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
unsigned int *valp,
int write, void *data)
{
struct do_proc_dopipe_max_size_conv_param *param = data;
if (write) {
unsigned int val;
@ -2635,9 +2628,6 @@ static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
if (val == 0)
return -EINVAL;
if (param->min && *param->min > val)
return -ERANGE;
*valp = val;
} else {
unsigned int val = *valp;
@ -2650,11 +2640,8 @@ static int do_proc_dopipe_max_size_conv(unsigned long *lvalp,
int proc_dopipe_max_size(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
struct do_proc_dopipe_max_size_conv_param param = {
.min = (unsigned int *) table->extra1,
};
return do_proc_douintvec(table, write, buffer, lenp, ppos,
do_proc_dopipe_max_size_conv, &param);
do_proc_dopipe_max_size_conv, NULL);
}
static void validate_coredump_safety(void)