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authorEric Biggers <ebiggers@google.com>2018-02-06 15:41:45 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 18:32:47 -0800
commit4c2e4befb3cc9ce42d506aa537c9ab504723e98c (patch)
tree5419e5965a7f07a39d1db8767148d547907f9c0d
parente7c52b84fb18f08ce49b6067ae6285aca79084a8 (diff)
pipe, sysctl: drop 'min' parameter from pipe-max-size converter
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>
-rw-r--r--fs/pipe.c10
-rw-r--r--include/linux/pipe_fs_i.h2
-rw-r--r--kernel/sysctl.c15
3 files changed, 5 insertions, 22 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index a449ca0ec0c6..1f6ec1051e59 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -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)
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index 2dc5e9870fcd..7d9beda14584 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -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 *);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 2fb4e27c636a..f21375aa6cf6 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -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)

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