From dabba87229411a5e9d20ac03ffc36463c53ae672 Mon Sep 17 00:00:00 2001 From: Pasha Tatashin Date: Fri, 27 May 2022 02:55:34 +0000 Subject: [PATCH] fs/kernel_read_file: allow to read files up-to ssize_t Patch series "Allow to kexec with initramfs larger than 2G", v2. Currently, the largest initramfs that is supported by kexec_file_load() syscall is 2G. This is because kernel_read_file() returns int, and is limited to INT_MAX or 2G. On the other hand, there are kexec based boot loaders (i.e. u-root), that may need to boot netboot images that might be larger than 2G. The first patch changes the return type from int to ssize_t in kernel_read_file* functions. The second patch increases the maximum initramfs file size to 4G. Tested: verified that can kexec_file_load() works with 4G initramfs on x86_64. This patch (of 2): Currently, the maximum file size that is supported is 2G. This may be too small in some cases. For example, kexec_file_load() system call loads initramfs. In some netboot cases initramfs can be rather large. Allow to use up-to ssize_t bytes. The callers still can limit the maximum file size via buf_size. Link: https://lkml.kernel.org/r/20220527025535.3953665-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20220527025535.3953665-2-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin Cc: Al Viro Cc: Baoquan He Cc: "Eric W. Biederman" Cc: Greg Thelen Cc: Sasha Levin Signed-off-by: Andrew Morton --- fs/kernel_read_file.c | 38 ++++++++++++++++---------------- include/linux/kernel_read_file.h | 32 +++++++++++++-------------- include/linux/limits.h | 1 + 3 files changed, 36 insertions(+), 35 deletions(-) diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c index 1b07550485b9..5d826274570c 100644 --- a/fs/kernel_read_file.c +++ b/fs/kernel_read_file.c @@ -29,15 +29,15 @@ * change between calls to kernel_read_file(). * * Returns number of bytes read (no single read will be bigger - * than INT_MAX), or negative on error. + * than SSIZE_MAX), or negative on error. * */ -int kernel_read_file(struct file *file, loff_t offset, void **buf, - size_t buf_size, size_t *file_size, - enum kernel_read_file_id id) +ssize_t kernel_read_file(struct file *file, loff_t offset, void **buf, + size_t buf_size, size_t *file_size, + enum kernel_read_file_id id) { loff_t i_size, pos; - size_t copied; + ssize_t copied; void *allocated = NULL; bool whole_file; int ret; @@ -58,7 +58,7 @@ int kernel_read_file(struct file *file, loff_t offset, void **buf, goto out; } /* The file is too big for sane activities. */ - if (i_size > INT_MAX) { + if (i_size > SSIZE_MAX) { ret = -EFBIG; goto out; } @@ -124,12 +124,12 @@ int kernel_read_file(struct file *file, loff_t offset, void **buf, } EXPORT_SYMBOL_GPL(kernel_read_file); -int kernel_read_file_from_path(const char *path, loff_t offset, void **buf, - size_t buf_size, size_t *file_size, - enum kernel_read_file_id id) +ssize_t kernel_read_file_from_path(const char *path, loff_t offset, void **buf, + size_t buf_size, size_t *file_size, + enum kernel_read_file_id id) { struct file *file; - int ret; + ssize_t ret; if (!path || !*path) return -EINVAL; @@ -144,14 +144,14 @@ int kernel_read_file_from_path(const char *path, loff_t offset, void **buf, } EXPORT_SYMBOL_GPL(kernel_read_file_from_path); -int kernel_read_file_from_path_initns(const char *path, loff_t offset, - void **buf, size_t buf_size, - size_t *file_size, - enum kernel_read_file_id id) +ssize_t kernel_read_file_from_path_initns(const char *path, loff_t offset, + void **buf, size_t buf_size, + size_t *file_size, + enum kernel_read_file_id id) { struct file *file; struct path root; - int ret; + ssize_t ret; if (!path || !*path) return -EINVAL; @@ -171,12 +171,12 @@ int kernel_read_file_from_path_initns(const char *path, loff_t offset, } EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns); -int kernel_read_file_from_fd(int fd, loff_t offset, void **buf, - size_t buf_size, size_t *file_size, - enum kernel_read_file_id id) +ssize_t kernel_read_file_from_fd(int fd, loff_t offset, void **buf, + size_t buf_size, size_t *file_size, + enum kernel_read_file_id id) { struct fd f = fdget(fd); - int ret = -EBADF; + ssize_t ret = -EBADF; if (!f.file || !(f.file->f_mode & FMODE_READ)) goto out; diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h index 575ffa1031d3..90451e2e12bd 100644 --- a/include/linux/kernel_read_file.h +++ b/include/linux/kernel_read_file.h @@ -35,21 +35,21 @@ static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id) return kernel_read_file_str[id]; } -int kernel_read_file(struct file *file, loff_t offset, - void **buf, size_t buf_size, - size_t *file_size, - enum kernel_read_file_id id); -int kernel_read_file_from_path(const char *path, loff_t offset, - void **buf, size_t buf_size, - size_t *file_size, - enum kernel_read_file_id id); -int kernel_read_file_from_path_initns(const char *path, loff_t offset, - void **buf, size_t buf_size, - size_t *file_size, - enum kernel_read_file_id id); -int kernel_read_file_from_fd(int fd, loff_t offset, - void **buf, size_t buf_size, - size_t *file_size, - enum kernel_read_file_id id); +ssize_t kernel_read_file(struct file *file, loff_t offset, + void **buf, size_t buf_size, + size_t *file_size, + enum kernel_read_file_id id); +ssize_t kernel_read_file_from_path(const char *path, loff_t offset, + void **buf, size_t buf_size, + size_t *file_size, + enum kernel_read_file_id id); +ssize_t kernel_read_file_from_path_initns(const char *path, loff_t offset, + void **buf, size_t buf_size, + size_t *file_size, + enum kernel_read_file_id id); +ssize_t kernel_read_file_from_fd(int fd, loff_t offset, + void **buf, size_t buf_size, + size_t *file_size, + enum kernel_read_file_id id); #endif /* _LINUX_KERNEL_READ_FILE_H */ diff --git a/include/linux/limits.h b/include/linux/limits.h index b568b9c30bbf..f6bcc9369010 100644 --- a/include/linux/limits.h +++ b/include/linux/limits.h @@ -7,6 +7,7 @@ #include #define SIZE_MAX (~(size_t)0) +#define SSIZE_MAX ((ssize_t)(SIZE_MAX >> 1)) #define PHYS_ADDR_MAX (~(phys_addr_t)0) #define U8_MAX ((u8)~0U)