From e40ba6d56b41754b37b995dbc8035b2b3a6afd8a Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Thu, 19 Nov 2015 12:39:22 -0500 Subject: [PATCH] firmware: replace call to fw_read_file_contents() with kernel version Replace the fw_read_file_contents with kernel_file_read_from_path(). Although none of the upstreamed LSMs define a kernel_fw_from_file hook, IMA is called by the security function to prevent unsigned firmware from being loaded and to measure/appraise signed firmware, based on policy. Instead of reading the firmware twice, once for measuring/appraising the firmware and again for reading the firmware contents into memory, the kernel_post_read_file() security hook calculates the file hash based on the in memory file buffer. The firmware is read once. This patch removes the LSM kernel_fw_from_file() hook and security call. Changelog v4+: - revert dropped buf->size assignment - reported by Sergey Senozhatsky v3: - remove kernel_fw_from_file hook - use kernel_file_read_from_path() - requested by Luis v2: - reordered and squashed firmware patches - fix MAX firmware size (Kees Cook) Signed-off-by: Mimi Zohar Acked-by: Kees Cook Acked-by: Luis R. Rodriguez --- drivers/base/firmware_class.c | 52 ++++++------------------------- include/linux/fs.h | 1 + include/linux/ima.h | 6 ---- include/linux/lsm_hooks.h | 11 ------- include/linux/security.h | 7 ----- security/integrity/ima/ima_main.c | 21 ++++++------- security/security.c | 13 -------- 7 files changed, 21 insertions(+), 90 deletions(-) diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index c743a2f18c33..a414008ea64c 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -291,37 +292,6 @@ static const char * const fw_path[] = { module_param_string(path, fw_path_para, sizeof(fw_path_para), 0644); MODULE_PARM_DESC(path, "customized firmware image search path with a higher priority than default path"); -static int fw_read_file_contents(struct file *file, struct firmware_buf *fw_buf) -{ - int size; - char *buf; - int rc; - - if (!S_ISREG(file_inode(file)->i_mode)) - return -EINVAL; - size = i_size_read(file_inode(file)); - if (size <= 0) - return -EINVAL; - buf = vmalloc(size); - if (!buf) - return -ENOMEM; - rc = kernel_read(file, 0, buf, size); - if (rc != size) { - if (rc > 0) - rc = -EIO; - goto fail; - } - rc = security_kernel_fw_from_file(file, buf, size); - if (rc) - goto fail; - fw_buf->data = buf; - fw_buf->size = size; - return 0; -fail: - vfree(buf); - return rc; -} - static void fw_finish_direct_load(struct device *device, struct firmware_buf *buf) { @@ -334,6 +304,7 @@ static void fw_finish_direct_load(struct device *device, static int fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf) { + loff_t size; int i, len; int rc = -ENOENT; char *path; @@ -343,8 +314,6 @@ static int fw_get_filesystem_firmware(struct device *device, return -ENOMEM; for (i = 0; i < ARRAY_SIZE(fw_path); i++) { - struct file *file; - /* skip the unset customized path */ if (!fw_path[i][0]) continue; @@ -356,18 +325,16 @@ static int fw_get_filesystem_firmware(struct device *device, break; } - file = filp_open(path, O_RDONLY, 0); - if (IS_ERR(file)) - continue; - rc = fw_read_file_contents(file, buf); - fput(file); + buf->size = 0; + rc = kernel_read_file_from_path(path, &buf->data, &size, + INT_MAX, READING_FIRMWARE); if (rc) { dev_warn(device, "loading %s failed with error %d\n", path, rc); continue; } - dev_dbg(device, "direct-loading %s\n", - buf->fw_id); + dev_dbg(device, "direct-loading %s\n", buf->fw_id); + buf->size = size; fw_finish_direct_load(device, buf); break; } @@ -689,8 +656,9 @@ static ssize_t firmware_loading_store(struct device *dev, dev_err(dev, "%s: map pages failed\n", __func__); else - rc = security_kernel_fw_from_file(NULL, - fw_buf->data, fw_buf->size); + rc = security_kernel_post_read_file(NULL, + fw_buf->data, fw_buf->size, + READING_FIRMWARE); /* * Same logic as fw_load_abort, only the DONE bit diff --git a/include/linux/fs.h b/include/linux/fs.h index 00fa5c45fd63..c8bc4d8c843f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2577,6 +2577,7 @@ static inline void i_readcount_inc(struct inode *inode) extern int do_pipe_flags(int *, int); enum kernel_read_file_id { + READING_FIRMWARE = 1, READING_MAX_ID }; diff --git a/include/linux/ima.h b/include/linux/ima.h index d29a6a23fc19..7aea4863c244 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -19,7 +19,6 @@ extern int ima_file_check(struct file *file, int mask, int opened); extern void ima_file_free(struct file *file); extern int ima_file_mmap(struct file *file, unsigned long prot); extern int ima_module_check(struct file *file); -extern int ima_fw_from_file(struct file *file, char *buf, size_t size); extern int ima_post_read_file(struct file *file, void *buf, loff_t size, enum kernel_read_file_id id); @@ -49,11 +48,6 @@ static inline int ima_module_check(struct file *file) return 0; } -static inline int ima_fw_from_file(struct file *file, char *buf, size_t size) -{ - return 0; -} - static inline int ima_post_read_file(struct file *file, void *buf, loff_t size, enum kernel_read_file_id id) { diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 2337f33913c1..7d04a1220223 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -541,15 +541,6 @@ * @inode points to the inode to use as a reference. * The current task must be the one that nominated @inode. * Return 0 if successful. - * @kernel_fw_from_file: - * Load firmware from userspace (not called for built-in firmware). - * @file contains the file structure pointing to the file containing - * the firmware to load. This argument will be NULL if the firmware - * was loaded via the uevent-triggered blob-based interface exposed - * by CONFIG_FW_LOADER_USER_HELPER. - * @buf pointer to buffer containing firmware contents. - * @size length of the firmware contents. - * Return 0 if permission is granted. * @kernel_module_request: * Ability to trigger the kernel to automatically upcall to userspace for * userspace to load a kernel module with the given name. @@ -1462,7 +1453,6 @@ union security_list_options { void (*cred_transfer)(struct cred *new, const struct cred *old); int (*kernel_act_as)(struct cred *new, u32 secid); int (*kernel_create_files_as)(struct cred *new, struct inode *inode); - int (*kernel_fw_from_file)(struct file *file, char *buf, size_t size); int (*kernel_module_request)(char *kmod_name); int (*kernel_module_from_file)(struct file *file); int (*kernel_post_read_file)(struct file *file, char *buf, loff_t size, @@ -1725,7 +1715,6 @@ struct security_hook_heads { struct list_head cred_transfer; struct list_head kernel_act_as; struct list_head kernel_create_files_as; - struct list_head kernel_fw_from_file; struct list_head kernel_post_read_file; struct list_head kernel_module_request; struct list_head kernel_module_from_file; diff --git a/include/linux/security.h b/include/linux/security.h index d920718dc845..cee1349e1155 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -300,7 +300,6 @@ int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp); void security_transfer_creds(struct cred *new, const struct cred *old); int security_kernel_act_as(struct cred *new, u32 secid); int security_kernel_create_files_as(struct cred *new, struct inode *inode); -int security_kernel_fw_from_file(struct file *file, char *buf, size_t size); int security_kernel_module_request(char *kmod_name); int security_kernel_module_from_file(struct file *file); int security_kernel_post_read_file(struct file *file, char *buf, loff_t size, @@ -854,12 +853,6 @@ static inline int security_kernel_create_files_as(struct cred *cred, return 0; } -static inline int security_kernel_fw_from_file(struct file *file, - char *buf, size_t size) -{ - return 0; -} - static inline int security_kernel_module_request(char *kmod_name) { return 0; diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 757765354158..e9651be17b72 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -337,17 +337,6 @@ int ima_module_check(struct file *file) return process_measurement(file, NULL, 0, MAY_EXEC, MODULE_CHECK, 0); } -int ima_fw_from_file(struct file *file, char *buf, size_t size) -{ - if (!file) { - if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && - (ima_appraise & IMA_APPRAISE_ENFORCE)) - return -EACCES; /* INTEGRITY_UNKNOWN */ - return 0; - } - return process_measurement(file, NULL, 0, MAY_EXEC, FIRMWARE_CHECK, 0); -} - /** * ima_post_read_file - in memory collect/appraise/audit measurement * @file: pointer to the file to be measured/appraised/audit @@ -366,12 +355,22 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, { enum ima_hooks func = FILE_CHECK; + if (!file && read_id == READING_FIRMWARE) { + if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && + (ima_appraise & IMA_APPRAISE_ENFORCE)) + return -EACCES; /* INTEGRITY_UNKNOWN */ + return 0; + } + if (!file || !buf || size == 0) { /* should never happen */ if (ima_appraise & IMA_APPRAISE_ENFORCE) return -EACCES; return 0; } + if (read_id == READING_FIRMWARE) + func = FIRMWARE_CHECK; + return process_measurement(file, buf, size, MAY_READ, func, 0); } diff --git a/security/security.c b/security/security.c index ef4c65a9fd17..cd85be61c416 100644 --- a/security/security.c +++ b/security/security.c @@ -884,17 +884,6 @@ int security_kernel_create_files_as(struct cred *new, struct inode *inode) return call_int_hook(kernel_create_files_as, 0, new, inode); } -int security_kernel_fw_from_file(struct file *file, char *buf, size_t size) -{ - int ret; - - ret = call_int_hook(kernel_fw_from_file, 0, file, buf, size); - if (ret) - return ret; - return ima_fw_from_file(file, buf, size); -} -EXPORT_SYMBOL_GPL(security_kernel_fw_from_file); - int security_kernel_module_request(char *kmod_name) { return call_int_hook(kernel_module_request, 0, kmod_name); @@ -1703,8 +1692,6 @@ struct security_hook_heads security_hook_heads = { LIST_HEAD_INIT(security_hook_heads.kernel_act_as), .kernel_create_files_as = LIST_HEAD_INIT(security_hook_heads.kernel_create_files_as), - .kernel_fw_from_file = - LIST_HEAD_INIT(security_hook_heads.kernel_fw_from_file), .kernel_module_request = LIST_HEAD_INIT(security_hook_heads.kernel_module_request), .kernel_module_from_file = -- 2.20.1