Messages in this thread | | | Subject | Re: [PATCH 06/13] fs/kernel_read_file: Remove redundant size argument | From | Scott Branden <> | Date | Fri, 17 Jul 2020 12:55:37 -0700 |
| |
On 2020-07-17 12:04 p.m., Scott Branden wrote: > Hi Kees, > > On 2020-07-17 10:43 a.m., Kees Cook wrote: >> In preparation for refactoring kernel_read_file*(), remove the redundant >> "size" argument which is not needed: it can be included in the return > I don't think the size argument is redundant though. > The existing kernel_read_file functions always read the whole file. > Now, what happens if the file is bigger than the buffer. > How does kernel_read_file know it read the whole file by looking at > the return value? Actually, this change looks ok dealing with the size. I'll look at the rest. > >> code, with callers adjusted. (VFS reads already cannot be larger than >> INT_MAX.) >> >> Signed-off-by: Kees Cook <keescook@chromium.org> >> --- >> drivers/base/firmware_loader/main.c | 8 ++++---- >> fs/kernel_read_file.c | 20 +++++++++----------- >> include/linux/kernel_read_file.h | 8 ++++---- >> kernel/kexec_file.c | 13 ++++++------- >> kernel/module.c | 7 +++---- >> security/integrity/digsig.c | 5 +++-- >> security/integrity/ima/ima_fs.c | 5 +++-- >> 7 files changed, 32 insertions(+), 34 deletions(-) >> >> diff --git a/drivers/base/firmware_loader/main.c >> b/drivers/base/firmware_loader/main.c >> index d4a413ea48ce..ea419c7d3d34 100644 >> --- a/drivers/base/firmware_loader/main.c >> +++ b/drivers/base/firmware_loader/main.c >> @@ -462,7 +462,7 @@ fw_get_filesystem_firmware(struct device *device, >> struct fw_priv *fw_priv, >> size_t in_size, >> const void *in_buffer)) >> { >> - loff_t size; >> + size_t size; >> int i, len; >> int rc = -ENOENT; >> char *path; >> @@ -494,10 +494,9 @@ fw_get_filesystem_firmware(struct device >> *device, struct fw_priv *fw_priv, >> fw_priv->size = 0; >> /* load firmware files from the mount namespace of init */ >> - rc = kernel_read_file_from_path_initns(path, &buffer, >> - &size, msize, >> + rc = kernel_read_file_from_path_initns(path, &buffer, msize, >> READING_FIRMWARE); >> - if (rc) { >> + if (rc < 0) { >> if (rc != -ENOENT) >> dev_warn(device, "loading %s failed with error %d\n", >> path, rc); >> @@ -506,6 +505,7 @@ fw_get_filesystem_firmware(struct device *device, >> struct fw_priv *fw_priv, >> path); >> continue; >> } >> + size = rc; >> dev_dbg(device, "Loading firmware from %s\n", path); >> if (decompress) { >> dev_dbg(device, "f/w decompressing %s\n", >> diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c >> index 54d972d4befc..dc28a8def597 100644 >> --- a/fs/kernel_read_file.c >> +++ b/fs/kernel_read_file.c >> @@ -5,7 +5,7 @@ >> #include <linux/security.h> >> #include <linux/vmalloc.h> >> -int kernel_read_file(struct file *file, void **buf, loff_t *size, >> +int kernel_read_file(struct file *file, void **buf, >> loff_t max_size, enum kernel_read_file_id id) >> { >> loff_t i_size, pos; >> @@ -29,7 +29,7 @@ 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)) { >> + if (i_size > INT_MAX || (max_size > 0 && i_size > max_size)) { > Should this be SSIZE_MAX? >> ret = -EFBIG; >> goto out; >> } >> @@ -59,8 +59,6 @@ int kernel_read_file(struct file *file, void **buf, >> loff_t *size, >> } >> ret = security_kernel_post_read_file(file, *buf, i_size, id); >> - if (!ret) >> - *size = pos; >> out_free: >> if (ret < 0) { >> @@ -72,11 +70,11 @@ int kernel_read_file(struct file *file, void >> **buf, loff_t *size, >> out: >> allow_write_access(file); >> - return ret; >> + return ret == 0 ? pos : ret; >> } >> EXPORT_SYMBOL_GPL(kernel_read_file); >> -int kernel_read_file_from_path(const char *path, void **buf, >> loff_t *size, >> +int kernel_read_file_from_path(const char *path, void **buf, >> loff_t max_size, enum kernel_read_file_id id) >> { >> struct file *file; >> @@ -89,14 +87,14 @@ 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_read_file(file, buf, max_size, id); >> fput(file); >> return ret; >> } >> 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, >> + loff_t max_size, >> enum kernel_read_file_id id) >> { >> struct file *file; >> @@ -115,13 +113,13 @@ 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_read_file(file, buf, max_size, id); >> fput(file); >> return ret; >> } >> 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, >> +int kernel_read_file_from_fd(int fd, void **buf, loff_t max_size, >> enum kernel_read_file_id id) >> { >> struct fd f = fdget(fd); >> @@ -130,7 +128,7 @@ 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_read_file(f.file, buf, max_size, id); >> out: >> fdput(f); >> return ret; >> diff --git a/include/linux/kernel_read_file.h >> b/include/linux/kernel_read_file.h >> index 78cf3d7dc835..0ca0bdbed1bd 100644 >> --- a/include/linux/kernel_read_file.h >> +++ b/include/linux/kernel_read_file.h >> @@ -36,16 +36,16 @@ static inline const char >> *kernel_read_file_id_str(enum kernel_read_file_id id) >> } >> int kernel_read_file(struct file *file, >> - void **buf, loff_t *size, loff_t max_size, >> + void **buf, loff_t max_size, >> enum kernel_read_file_id id); >> int kernel_read_file_from_path(const char *path, >> - void **buf, loff_t *size, loff_t max_size, >> + void **buf, loff_t max_size, >> enum kernel_read_file_id id); >> int kernel_read_file_from_path_initns(const char *path, >> - void **buf, loff_t *size, loff_t max_size, >> + void **buf, loff_t max_size, >> enum kernel_read_file_id id); >> int kernel_read_file_from_fd(int fd, >> - void **buf, loff_t *size, loff_t max_size, >> + void **buf, loff_t max_size, >> enum kernel_read_file_id id); >> #endif /* _LINUX_KERNEL_READ_FILE_H */ >> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c >> index 1358069ce9e9..a201bbb19158 100644 >> --- a/kernel/kexec_file.c >> +++ b/kernel/kexec_file.c >> @@ -220,13 +220,12 @@ kimage_file_prepare_segments(struct kimage >> *image, int kernel_fd, int initrd_fd, >> { >> int ret; >> void *ldata; >> - loff_t size; >> ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf, >> - &size, INT_MAX, READING_KEXEC_IMAGE); >> - if (ret) >> + INT_MAX, READING_KEXEC_IMAGE); >> + if (ret < 0) >> return ret; >> - image->kernel_buf_len = size; >> + image->kernel_buf_len = ret; >> /* Call arch image probe handlers */ >> ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, >> @@ -243,11 +242,11 @@ kimage_file_prepare_segments(struct kimage >> *image, int kernel_fd, int initrd_fd, >> /* It is possible that there no initramfs is being loaded */ >> if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { >> ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf, >> - &size, INT_MAX, >> + INT_MAX, >> READING_KEXEC_INITRAMFS); >> - if (ret) >> + if (ret < 0) >> goto out; >> - image->initrd_buf_len = size; >> + image->initrd_buf_len = ret; >> } >> if (cmdline_len) { >> diff --git a/kernel/module.c b/kernel/module.c >> index e9765803601b..b6fd4f51cc30 100644 >> --- a/kernel/module.c >> +++ b/kernel/module.c >> @@ -3988,7 +3988,6 @@ SYSCALL_DEFINE3(init_module, void __user *, umod, >> SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, >> int, flags) >> { >> struct load_info info = { }; >> - loff_t size; >> void *hdr = NULL; >> int err; >> @@ -4002,12 +4001,12 @@ SYSCALL_DEFINE3(finit_module, int, fd, >> const char __user *, uargs, int, flags) >> |MODULE_INIT_IGNORE_VERMAGIC)) >> return -EINVAL; >> - err = kernel_read_file_from_fd(fd, &hdr, &size, INT_MAX, >> + err = kernel_read_file_from_fd(fd, &hdr, INT_MAX, >> READING_MODULE); >> - if (err) >> + if (err < 0) >> return err; >> info.hdr = hdr; >> - info.len = size; >> + info.len = err; >> return load_module(&info, uargs, flags); >> } >> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c >> index f8869be45d8f..97661ffabc4e 100644 >> --- a/security/integrity/digsig.c >> +++ b/security/integrity/digsig.c >> @@ -171,16 +171,17 @@ int __init integrity_add_key(const unsigned int >> id, const void *data, >> int __init integrity_load_x509(const unsigned int id, const char >> *path) >> { >> void *data = NULL; >> - loff_t size; >> + size_t size; >> int rc; >> key_perm_t perm; >> - rc = kernel_read_file_from_path(path, &data, &size, 0, >> + rc = kernel_read_file_from_path(path, &data, 0, >> READING_X509_CERTIFICATE); >> if (rc < 0) { >> pr_err("Unable to open file: %s (%d)", path, rc); >> return rc; >> } >> + size = rc; >> perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | >> KEY_USR_READ; >> diff --git a/security/integrity/ima/ima_fs.c >> b/security/integrity/ima/ima_fs.c >> index e13ffece3726..9ba145d3d6d9 100644 >> --- a/security/integrity/ima/ima_fs.c >> +++ b/security/integrity/ima/ima_fs.c >> @@ -275,7 +275,7 @@ static ssize_t ima_read_policy(char *path) >> { >> void *data = NULL; >> char *datap; >> - loff_t size; >> + size_t size; >> int rc, pathlen = strlen(path); >> char *p; >> @@ -284,11 +284,12 @@ static ssize_t ima_read_policy(char *path) >> datap = path; >> strsep(&datap, "\n"); >> - rc = kernel_read_file_from_path(path, &data, &size, 0, >> READING_POLICY); >> + rc = kernel_read_file_from_path(path, &data, 0, READING_POLICY); >> if (rc < 0) { >> pr_err("Unable to open file: %s (%d)", path, rc); >> return rc; >> } >> + size = rc; >> datap = data; >> while (size > 0 && (p = strsep(&datap, "\n"))) { >
| |