Add kernel_pread_file* support to kernel to allow for partial read
of files with an offset into the file. Existing kernel_read_file
functions call new kernel_pread_file functions with offset=0 and
flags=KERNEL_PREAD_FLAG_WHOLE.
Signed-off-by: Scott Branden <scott.branden@xxxxxxxxxxxx>
---
fs/exec.c | 77 ++++++++++++++++++++++++++++++++++++----------
include/linux/fs.h | 15 +++++++++
2 files changed, 75 insertions(+), 17 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index db17be51b112..a38f8fb432fa 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -896,10 +896,14 @@ struct file *open_exec(const char *name)
}
EXPORT_SYMBOL(open_exec);
-int kernel_read_file(struct file *file, void **buf, loff_t *size,
- loff_t max_size, enum kernel_read_file_id id)
-{
- loff_t i_size, pos;
+int kernel_pread_file(struct file *file, void **buf, loff_t *size,
+ loff_t pos, loff_t max_size, unsigned int flags,
+ enum kernel_read_file_id id)
+{
+ loff_t alloc_size;
+ loff_t buf_pos;
+ loff_t read_end;
+ loff_t i_size;
ssize_t bytes = 0;
int ret;
@@ -919,21 +923,31 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
ret = -EINVAL;
goto out;
}
- if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
+
+ /* Default read to end of file */
+ read_end = i_size;
+
+ /* Allow reading partial portion of file */
+ if ((flags & KERNEL_PREAD_FLAG_PART) &&
+ (i_size > (pos + max_size)))
+ read_end = pos + max_size;
+
+ alloc_size = read_end - pos;
+ if (i_size > SIZE_MAX || (max_size > 0 && alloc_size > max_size)) {
ret = -EFBIG;
goto out;
}
if (id != READING_FIRMWARE_PREALLOC_BUFFER)
- *buf = vmalloc(i_size);
+ *buf = vmalloc(alloc_size);
if (!*buf) {
ret = -ENOMEM;
goto out;
}
- pos = 0;
- while (pos < i_size) {
- bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
+ buf_pos = 0;
+ while (pos < read_end) {
+ bytes = kernel_read(file, *buf + buf_pos, read_end - pos, &pos);
if (bytes < 0) {
ret = bytes;
goto out_free;
@@ -941,14 +955,16 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
if (bytes == 0)
break;
+
+ buf_pos += bytes;
}
- if (pos != i_size) {
+ if (pos != read_end) {
ret = -EIO;
goto out_free;
}
- ret = security_kernel_post_read_file(file, *buf, i_size, id);
+ ret = security_kernel_post_read_file(file, *buf, alloc_size, id);
if (!ret)
*size = pos;
@@ -964,10 +980,20 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
allow_write_access(file);
return ret;
}
+EXPORT_SYMBOL_GPL(kernel_pread_file);
+
+int kernel_read_file(struct file *file, void **buf, loff_t *size,
+ loff_t max_size, enum kernel_read_file_id id)
+{
+ return kernel_pread_file(file, buf, size, 0, max_size,
+ KERNEL_PREAD_FLAG_WHOLE, id);
+}
EXPORT_SYMBOL_GPL(kernel_read_file);
-int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
- loff_t max_size, enum kernel_read_file_id id)
+int kernel_pread_file_from_path(const char *path, void **buf,
+ loff_t *size, loff_t pos,
+ loff_t max_size, unsigned int flags,
+ enum kernel_read_file_id id)
{
struct file *file;
int ret;
@@ -979,14 +1005,23 @@ int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
if (IS_ERR(file))
return PTR_ERR(file);
- ret = kernel_read_file(file, buf, size, max_size, id);
+ ret = kernel_pread_file(file, buf, size, pos, max_size, flags, id);
fput(file);
return ret;
}
+EXPORT_SYMBOL_GPL(kernel_pread_file_from_path);
+
+int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
+ loff_t max_size, enum kernel_read_file_id id)
+{
+ return kernel_pread_file_from_path(path, buf, size, 0, max_size,
+ KERNEL_PREAD_FLAG_WHOLE, id);
+}
EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
-int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
- enum kernel_read_file_id id)
+int kernel_pread_file_from_fd(int fd, void **buf, loff_t *size, loff_t pos,
+ loff_t max_size, unsigned int flags,
+ enum kernel_read_file_id id)
{
struct fd f = fdget(fd);
int ret = -EBADF;
@@ -994,11 +1029,19 @@ int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
if (!f.file)
goto out;
- ret = kernel_read_file(f.file, buf, size, max_size, id);
+ ret = kernel_pread_file(f.file, buf, size, pos, max_size, flags, id);
out:
fdput(f);
return ret;
}
+EXPORT_SYMBOL_GPL(kernel_pread_file_from_fd);
+
+int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
+ enum kernel_read_file_id id)
+{
+ return kernel_pread_file_from_fd(fd, buf, size, 0, max_size,
+ KERNEL_PREAD_FLAG_WHOLE, id);
+}
EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3cd4fe6b845e..8f39530cfcc2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3008,10 +3008,25 @@ static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id)
return kernel_read_file_str[id];
}
+/* Flags used by kernel_pread_file functions */
+#define KERNEL_PREAD_FLAG_WHOLE 0x0000 /* Only Allow reading of whole file */
+#define KERNEL_PREAD_FLAG_PART 0x0001 /* Allow reading part of file */
+
+extern int kernel_pread_file(struct file *file, void **buf, loff_t *size,
+ loff_t pos, loff_t max_size, unsigned int flags,
+ enum kernel_read_file_id id);
extern int kernel_read_file(struct file *, void **, loff_t *, loff_t,
enum kernel_read_file_id);
+extern int kernel_pread_file_from_path(const char *path, void **buf,
+ loff_t *size, loff_t pos,
+ loff_t max_size, unsigned int flags,
+ enum kernel_read_file_id id);
extern int kernel_read_file_from_path(const char *, void **, loff_t *, loff_t,
enum kernel_read_file_id);
+extern int kernel_pread_file_from_fd(int fd, void **buf, loff_t *size,
+ loff_t pos, loff_t max_size,
+ unsigned int flags,
+ enum kernel_read_file_id id);
extern int kernel_read_file_from_fd(int, void **, loff_t *, loff_t,
enum kernel_read_file_id);
extern ssize_t kernel_read(struct file *, void *, size_t, loff_t *);
--
2.17.1
