1 files changed, 24 insertions, 33 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
index a449ca0..0913aed 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.
  */
@@ -610,12 +605,21 @@ static unsigned long account_pipe_buffers(struct user_struct *user,
 
 static bool too_many_pipe_buffers_soft(unsigned long user_bufs)
 {
-	return pipe_user_pages_soft && user_bufs >= pipe_user_pages_soft;
+	unsigned long soft_limit = READ_ONCE(pipe_user_pages_soft);
+
+	return soft_limit && user_bufs > soft_limit;
 }
 
 static bool too_many_pipe_buffers_hard(unsigned long user_bufs)
 {
-	return pipe_user_pages_hard && user_bufs >= pipe_user_pages_hard;
+	unsigned long hard_limit = READ_ONCE(pipe_user_pages_hard);
+
+	return hard_limit && user_bufs > hard_limit;
+}
+
+static bool is_unprivileged_user(void)
+{
+	return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
 }
 
 struct pipe_inode_info *alloc_pipe_info(void)
@@ -624,22 +628,23 @@ struct pipe_inode_info *alloc_pipe_info(void)
 	unsigned long pipe_bufs = PIPE_DEF_BUFFERS;
 	struct user_struct *user = get_current_user();
 	unsigned long user_bufs;
+	unsigned int max_size = READ_ONCE(pipe_max_size);
 
 	pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT);
 	if (pipe == NULL)
 		goto out_free_uid;
 
-	if (pipe_bufs * PAGE_SIZE > pipe_max_size && !capable(CAP_SYS_RESOURCE))
-		pipe_bufs = pipe_max_size >> PAGE_SHIFT;
+	if (pipe_bufs * PAGE_SIZE > max_size && !capable(CAP_SYS_RESOURCE))
+		pipe_bufs = max_size >> PAGE_SHIFT;
 
 	user_bufs = account_pipe_buffers(user, 0, pipe_bufs);
 
-	if (too_many_pipe_buffers_soft(user_bufs)) {
+	if (too_many_pipe_buffers_soft(user_bufs) && is_unprivileged_user()) {
 		user_bufs = account_pipe_buffers(user, pipe_bufs, 1);
 		pipe_bufs = 1;
 	}
 
-	if (too_many_pipe_buffers_hard(user_bufs))
+	if (too_many_pipe_buffers_hard(user_bufs) && is_unprivileged_user())
 		goto out_revert_acct;
 
 	pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
@@ -1020,18 +1025,16 @@ const struct file_operations pipefifo_fops = {
  * Currently we rely on the pipe array holding a power-of-2 number
  * of pages. Returns 0 on error.
  */
-unsigned int round_pipe_size(unsigned int size)
+unsigned int round_pipe_size(unsigned long size)
 {
-	unsigned long nr_pages;
-
-	if (size < pipe_min_size)
-		size = pipe_min_size;
-
-	nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	if (nr_pages == 0)
+	if (size > (1U << 31))
 		return 0;
 
-	return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;
+	/* Minimum pipe size, as required by POSIX */
+	if (size < PAGE_SIZE)
+		return PAGE_SIZE;
+
+	return roundup_pow_of_two(size);
 }
 
 /*
@@ -1046,8 +1049,6 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
 	long ret = 0;
 
 	size = round_pipe_size(arg);
-	if (size == 0)
-		return -EINVAL;
 	nr_pages = size >> PAGE_SHIFT;
 
 	if (!nr_pages)
@@ -1069,7 +1070,7 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg)
 	if (nr_pages > pipe->buffers &&
 			(too_many_pipe_buffers_hard(user_bufs) ||
 			 too_many_pipe_buffers_soft(user_bufs)) &&
-			!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
+			is_unprivileged_user()) {
 		ret = -EPERM;
 		goto out_revert_acct;
 	}
@@ -1125,16 +1126,6 @@ out_revert_acct:
 }
 
 /*
- * This should work even if CONFIG_PROC_FS isn't set, as proc_dopipe_max_size
- * will return an error.
- */
-int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
-		 size_t *lenp, loff_t *ppos)
-{
-	return proc_dopipe_max_size(table, write, buf, lenp, ppos);
-}
-
-/*
  * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
  * location, so checking ->i_pipe is not enough to verify that this is a
  * pipe.