In preparation for further refactoring of kernel_read_file*(), rename the "max_size" argument to the more accurate "buf_size", and correct its type to size_t. Add kerndoc to explain the specifics of how the arguments will be used. Note that with buf_size now size_t, it can no longer be negative (and was never called with a negative value). Adjust callers to use it as a "maximum size" when *buf is NULL.
Acked-by: Scott Branden scott.branden@broadcom.com Reviewed-by: Mimi Zohar zohar@linux.ibm.com Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Kees Cook keescook@chromium.org --- fs/kernel_read_file.c | 34 +++++++++++++++++++++++--------- include/linux/kernel_read_file.h | 8 ++++---- security/integrity/digsig.c | 2 +- security/integrity/ima/ima_fs.c | 2 +- 4 files changed, 31 insertions(+), 15 deletions(-)
diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c index dc28a8def597..e21a76001fff 100644 --- a/fs/kernel_read_file.c +++ b/fs/kernel_read_file.c @@ -5,15 +5,31 @@ #include <linux/security.h> #include <linux/vmalloc.h>
+/** + * kernel_read_file() - read file contents into a kernel buffer + * + * @file file to read from + * @buf pointer to a "void *" buffer for reading into (if + * *@buf is NULL, a buffer will be allocated, and + * @buf_size will be ignored) + * @buf_size size of buf, if already allocated. If @buf not + * allocated, this is the largest size to allocate. + * @id the kernel_read_file_id identifying the type of + * file contents being read (for LSMs to examine) + * + * Returns number of bytes read (no single read will be bigger + * than INT_MAX), or negative on error. + * + */ int kernel_read_file(struct file *file, void **buf, - loff_t max_size, enum kernel_read_file_id id) + size_t buf_size, enum kernel_read_file_id id) { loff_t i_size, pos; ssize_t bytes = 0; void *allocated = NULL; int ret;
- if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0) + if (!S_ISREG(file_inode(file)->i_mode)) return -EINVAL;
ret = deny_write_access(file); @@ -29,7 +45,7 @@ int kernel_read_file(struct file *file, void **buf, ret = -EINVAL; goto out; } - if (i_size > INT_MAX || (max_size > 0 && i_size > max_size)) { + if (i_size > INT_MAX || i_size > buf_size) { ret = -EFBIG; goto out; } @@ -75,7 +91,7 @@ int kernel_read_file(struct file *file, void **buf, EXPORT_SYMBOL_GPL(kernel_read_file);
int kernel_read_file_from_path(const char *path, void **buf, - loff_t max_size, enum kernel_read_file_id id) + size_t buf_size, enum kernel_read_file_id id) { struct file *file; int ret; @@ -87,14 +103,14 @@ int kernel_read_file_from_path(const char *path, void **buf, if (IS_ERR(file)) return PTR_ERR(file);
- ret = kernel_read_file(file, buf, max_size, id); + ret = kernel_read_file(file, buf, buf_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 max_size, + size_t buf_size, enum kernel_read_file_id id) { struct file *file; @@ -113,13 +129,13 @@ 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, max_size, id); + ret = kernel_read_file(file, buf, buf_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 max_size, +int kernel_read_file_from_fd(int fd, void **buf, size_t buf_size, enum kernel_read_file_id id) { struct fd f = fdget(fd); @@ -128,7 +144,7 @@ int kernel_read_file_from_fd(int fd, void **buf, loff_t max_size, if (!f.file) goto out;
- ret = kernel_read_file(f.file, buf, max_size, id); + ret = kernel_read_file(f.file, buf, buf_size, id); out: fdput(f); return ret; diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h index 0ca0bdbed1bd..910039e7593e 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 max_size, + void **buf, size_t buf_size, enum kernel_read_file_id id); int kernel_read_file_from_path(const char *path, - void **buf, loff_t max_size, + void **buf, size_t buf_size, enum kernel_read_file_id id); int kernel_read_file_from_path_initns(const char *path, - void **buf, loff_t max_size, + void **buf, size_t buf_size, enum kernel_read_file_id id); int kernel_read_file_from_fd(int fd, - void **buf, loff_t max_size, + void **buf, size_t buf_size, enum kernel_read_file_id id);
#endif /* _LINUX_KERNEL_READ_FILE_H */ diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c index 97661ffabc4e..04f779c4f5ed 100644 --- a/security/integrity/digsig.c +++ b/security/integrity/digsig.c @@ -175,7 +175,7 @@ int __init integrity_load_x509(const unsigned int id, const char *path) int rc; key_perm_t perm;
- rc = kernel_read_file_from_path(path, &data, 0, + rc = kernel_read_file_from_path(path, &data, INT_MAX, READING_X509_CERTIFICATE); if (rc < 0) { pr_err("Unable to open file: %s (%d)", path, rc); diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c index 602f52717757..692b83e82edf 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -284,7 +284,7 @@ static ssize_t ima_read_policy(char *path) datap = path; strsep(&datap, "\n");
- rc = kernel_read_file_from_path(path, &data, 0, READING_POLICY); + rc = kernel_read_file_from_path(path, &data, INT_MAX, READING_POLICY); if (rc < 0) { pr_err("Unable to open file: %s (%d)", path, rc); return rc;