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rw_verify_area(): saner calling conventions

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Lift length capping into the few callers that care about it.  Most of
them treat all non-negatives as "success" and ignore the capped value,
and with good reasons.

Make rw_verify_area() return 0 on success.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-03-31 21:48:20 -04:00
parent 2958ec177e
commit bc61384dcd
1 changed files with 14 additions and 19 deletions
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33
fs/read_write.c
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@ -410,11 +410,6 @@ ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos)
} }
EXPORT_SYMBOL(vfs_iter_write); EXPORT_SYMBOL(vfs_iter_write);
/*
* rw_verify_area doesn't like huge counts. We limit
* them to something that fits in "int" so that others
* won't have to do range checks all the time.
*/
int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t count) int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t count)
{ {
struct inode *inode; struct inode *inode;
@ -441,11 +436,8 @@ int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t
if (retval < 0) if (retval < 0)
return retval; return retval;
} }
retval = security_file_permission(file, return security_file_permission(file,
read_write == READ ? MAY_READ : MAY_WRITE); read_write == READ ? MAY_READ : MAY_WRITE);
if (retval)
return retval;
return count > MAX_RW_COUNT ? MAX_RW_COUNT : count;
} }
static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos) static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
@ -489,8 +481,9 @@ ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
return -EFAULT; return -EFAULT;
ret = rw_verify_area(READ, file, pos, count); ret = rw_verify_area(READ, file, pos, count);
if (ret >= 0) { if (!ret) {
count = ret; if (count > MAX_RW_COUNT)
count = MAX_RW_COUNT;
ret = __vfs_read(file, buf, count, pos); ret = __vfs_read(file, buf, count, pos);
if (ret > 0) { if (ret > 0) {
fsnotify_access(file); fsnotify_access(file);
@ -572,8 +565,9 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
return -EFAULT; return -EFAULT;
ret = rw_verify_area(WRITE, file, pos, count); ret = rw_verify_area(WRITE, file, pos, count);
if (ret >= 0) { if (!ret) {
count = ret; if (count > MAX_RW_COUNT)
count = MAX_RW_COUNT;
file_start_write(file); file_start_write(file);
ret = __vfs_write(file, buf, count, pos); ret = __vfs_write(file, buf, count, pos);
if (ret > 0) { if (ret > 0) {
@ -1323,7 +1317,8 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
retval = rw_verify_area(READ, in.file, &pos, count); retval = rw_verify_area(READ, in.file, &pos, count);
if (retval < 0) if (retval < 0)
goto fput_in; goto fput_in;
count = retval; if (count > MAX_RW_COUNT)
count = MAX_RW_COUNT;
/* /*
* Get output file, and verify that it is ok.. * Get output file, and verify that it is ok..
@ -1341,7 +1336,6 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
retval = rw_verify_area(WRITE, out.file, &out_pos, count); retval = rw_verify_area(WRITE, out.file, &out_pos, count);
if (retval < 0) if (retval < 0)
goto fput_out; goto fput_out;
count = retval;
if (!max) if (!max)
max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes); max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
@ -1485,11 +1479,12 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (flags != 0) if (flags != 0)
return -EINVAL; return -EINVAL;
/* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */
ret = rw_verify_area(READ, file_in, &pos_in, len); ret = rw_verify_area(READ, file_in, &pos_in, len);
if (ret >= 0) if (unlikely(ret))
ret = rw_verify_area(WRITE, file_out, &pos_out, len); return ret;
if (ret < 0)
ret = rw_verify_area(WRITE, file_out, &pos_out, len);
if (unlikely(ret))
return ret; return ret;
if (!(file_in->f_mode & FMODE_READ) || if (!(file_in->f_mode & FMODE_READ) ||