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authorAmir Goldstein <amir73il@gmail.com>2019-06-05 08:04:49 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-06-09 10:06:19 -0700
commit96e6e8f4a68df2d94800311163faa67124df24e5 (patch)
tree42b63675c58ce53f9896daf674937625e71a684d /mm/filemap.c
parent646955cd5425dd8fed8205cbb1b4373c222d028e (diff)
downloadlinux-96e6e8f4a68df2d94800311163faa67124df24e5.tar.bz2
vfs: add missing checks to copy_file_range
Like the clone and dedupe interfaces we've recently fixed, the copy_file_range() implementation is missing basic sanity, limits and boundary condition tests on the parameters that are passed to it from userspace. Create a new "generic_copy_file_checks()" function modelled on the generic_remap_checks() function to provide this missing functionality. [Amir] Shorten copy length instead of checking pos_in limits because input file size already abides by the limits. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 44361928bbb0..aac71aef4c61 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3056,6 +3056,59 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out)
return 0;
}
+/*
+ * Performs necessary checks before doing a file copy
+ *
+ * Can adjust amount of bytes to copy via @req_count argument.
+ * Returns appropriate error code that caller should return or
+ * zero in case the copy should be allowed.
+ */
+int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ size_t *req_count, unsigned int flags)
+{
+ struct inode *inode_in = file_inode(file_in);
+ struct inode *inode_out = file_inode(file_out);
+ uint64_t count = *req_count;
+ loff_t size_in;
+ int ret;
+
+ ret = generic_file_rw_checks(file_in, file_out);
+ if (ret)
+ return ret;
+
+ /* Don't touch certain kinds of inodes */
+ if (IS_IMMUTABLE(inode_out))
+ return -EPERM;
+
+ if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
+ return -ETXTBSY;
+
+ /* Ensure offsets don't wrap. */
+ if (pos_in + count < pos_in || pos_out + count < pos_out)
+ return -EOVERFLOW;
+
+ /* Shorten the copy to EOF */
+ size_in = i_size_read(inode_in);
+ if (pos_in >= size_in)
+ count = 0;
+ else
+ count = min(count, size_in - (uint64_t)pos_in);
+
+ ret = generic_write_check_limits(file_out, pos_out, &count);
+ if (ret)
+ return ret;
+
+ /* Don't allow overlapped copying within the same file. */
+ if (inode_in == inode_out &&
+ pos_out + count > pos_in &&
+ pos_out < pos_in + count)
+ return -EINVAL;
+
+ *req_count = count;
+ return 0;
+}
+
int pagecache_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)