Add kernel_pread_file* support to kernel to allow for partial read of files with an offset into the file.
Signed-off-by: Scott Branden <[email protected]> --- fs/exec.c | 93 ++++++++++++++++++++++++++++++++++------------ include/linux/fs.h | 15 ++++++++ 2 files changed, 85 insertions(+), 23 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 7b7cbb180785..c557b4b31d0f 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -927,10 +927,14 @@ 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 max_size, loff_t pos, + 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; @@ -950,21 +954,32 @@ 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 ((id == READING_FIRMWARE_PARTIAL_READ) && + (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); + if ((id != READING_FIRMWARE_PARTIAL_READ) && + (id != READING_FIRMWARE_PREALLOC_BUFFER)) + *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; @@ -972,20 +987,23 @@ 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; out_free: if (ret < 0) { - if (id != READING_FIRMWARE_PREALLOC_BUFFER) { + if ((id != READING_FIRMWARE_PARTIAL_READ) && + (id != READING_FIRMWARE_PREALLOC_BUFFER)) { vfree(*buf); *buf = NULL; } @@ -995,10 +1013,18 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size, allow_write_access(file); return ret; } + +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, max_size, 0, 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 max_size, loff_t pos, + enum kernel_read_file_id id) { struct file *file; int ret; @@ -1010,15 +1036,22 @@ 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, max_size, pos, id); fput(file); return ret; } + +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, max_size, 0, id); +} EXPORT_SYMBOL_GPL(kernel_read_file_from_path); -int kernel_read_file_from_path_initns(const char *path, void **buf, - loff_t *size, loff_t max_size, - enum kernel_read_file_id id) +int kernel_pread_file_from_path_initns(const char *path, void **buf, + loff_t *size, + loff_t max_size, loff_t pos, + enum kernel_read_file_id id) { struct file *file; struct path root; @@ -1036,14 +1069,22 @@ int kernel_read_file_from_path_initns(const char *path, void **buf, 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, max_size, pos, id); fput(file); return ret; } + +int kernel_read_file_from_path_initns(const char *path, void **buf, + loff_t *size, loff_t max_size, + enum kernel_read_file_id id) +{ + return kernel_pread_file_from_path_initns(path, buf, size, max_size, 0, id); +} EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns); -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 max_size, loff_t pos, + enum kernel_read_file_id id) { struct fd f = fdget(fd); int ret = -EBADF; @@ -1051,11 +1092,17 @@ 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, max_size, pos, id); out: fdput(f); return ret; } + +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, max_size, 0, id); +} EXPORT_SYMBOL_GPL(kernel_read_file_from_fd); #if defined(CONFIG_HAVE_AOUT) || defined(CONFIG_BINFMT_FLAT) || \ diff --git a/include/linux/fs.h b/include/linux/fs.h index 6931c469040b..3ac1d213577a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3012,6 +3012,7 @@ extern int do_pipe_flags(int *, int); #define __kernel_read_file_id(id) \ id(UNKNOWN, unknown) \ id(FIRMWARE, firmware) \ + id(FIRMWARE_PARTIAL_READ, firmware) \ id(FIRMWARE_PREALLOC_BUFFER, firmware) \ id(FIRMWARE_EFI_EMBEDDED, firmware) \ id(MODULE, kernel-module) \ @@ -3040,12 +3041,26 @@ static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id) return kernel_read_file_str[id]; } +int kernel_pread_file(struct file *file, void **buf, loff_t *size, + loff_t pos, loff_t max_size, + enum kernel_read_file_id id); extern int kernel_read_file(struct file *, void **, loff_t *, loff_t, enum kernel_read_file_id); +int kernel_pread_file_from_path(const char *path, void **buf, + loff_t *size, loff_t pos, + loff_t max_size, + 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); +int kernel_pread_file_from_path_initns(const char *path, void **buf, + loff_t *size, loff_t pos, + loff_t max_size, + enum kernel_read_file_id id); extern int kernel_read_file_from_path_initns(const char *, void **, loff_t *, loff_t, enum kernel_read_file_id); +int kernel_pread_file_from_fd(int fd, void **buf, loff_t *size, + loff_t pos, loff_t max_size, + 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
