fs/kernel_read_file: Remove FIRMWARE_PREALLOC_BUFFER enum

FIRMWARE_PREALLOC_BUFFER is a "how", not a "what", and confuses the LSMs
that are interested in filtering between types of things. The "how"
should be an internal detail made uninteresting to the LSMs.

Fixes: a098ecd2fa7d ("firmware: support loading into a pre-allocated buffer")
Fixes: fd90bc559bfb ("ima: based on policy verify firmware signatures (pre-allocated buffer)")
Fixes: 4f0496d8ffa3 ("ima: based on policy warn about loading firmware (pre-allocated buffer)")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201002173828.2099543-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index 63b9714..b0ec272 100644 (file)
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -470,14 +470,12 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
        int i, len;
        int rc = -ENOENT;
        char *path;
-       enum kernel_read_file_id id = READING_FIRMWARE;
        size_t msize = INT_MAX;
        void *buffer = NULL;
 
        /* Already populated data member means we're loading into a buffer */
        if (!decompress && fw_priv->data) {
                buffer = fw_priv->data;
-               id = READING_FIRMWARE_PREALLOC_BUFFER;
                msize = fw_priv->allocated_size;
        }
 
@@ -501,7 +499,8 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
 
                /* load firmware files from the mount namespace of init */
                rc = kernel_read_file_from_path_initns(path, &buffer,
-                                                      &size, msize, id);
+                                                      &size, msize,
+                                                      READING_FIRMWARE);
                if (rc) {
                        if (rc != -ENOENT)
                                dev_warn(device, "loading %s failed with error %d\n",

diff --git a/fs/exec.c b/fs/exec.c
index a91003e..9233cd5 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -954,6 +954,7 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
 {
        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)
@@ -977,8 +978,8 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
                goto out;
        }
 
-       if (id != READING_FIRMWARE_PREALLOC_BUFFER)
-               *buf = vmalloc(i_size);
+       if (!*buf)
+               *buf = allocated = vmalloc(i_size);
        if (!*buf) {
                ret = -ENOMEM;
                goto out;
@@ -1007,7 +1008,7 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
 
 out_free:
        if (ret < 0) {
-               if (id != READING_FIRMWARE_PREALLOC_BUFFER) {
+               if (allocated) {
                        vfree(*buf);
                        *buf = NULL;
                }

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7519ae0..7336e22 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2858,10 +2858,10 @@ static inline void i_readcount_inc(struct inode *inode)
 #endif
 extern int do_pipe_flags(int *, int);
 
+/* This is a list of *what* is being read, not *how*. */
 #define __kernel_read_file_id(id) \
        id(UNKNOWN, unknown)            \
        id(FIRMWARE, firmware)          \
-       id(FIRMWARE_PREALLOC_BUFFER, firmware)  \
        id(FIRMWARE_EFI_EMBEDDED, firmware)     \
        id(MODULE, kernel-module)               \
        id(KEXEC_IMAGE, kexec-image)            \

diff --git a/kernel/module.c b/kernel/module.c
index 1c5cff3..b2808ac 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -4035,7 +4035,7 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
 {
        struct load_info info = { };
        loff_t size;
-       void *hdr;
+       void *hdr = NULL;
        int err;
 
        err = may_init_module();

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index e9cbada..ac02b76 100644 (file)
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -169,7 +169,7 @@ 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;
+       void *data = NULL;
        loff_t size;
        int rc;
        key_perm_t perm;

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index e3fcad8..15a44c5 100644 (file)
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -272,7 +272,7 @@ static const struct file_operations ima_ascii_measurements_ops = {
 
 static ssize_t ima_read_policy(char *path)
 {
-       void *data;
+       void *data = NULL;
        char *datap;
        loff_t size;
        int rc, pathlen = strlen(path);

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 8a91711..2f18778 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -611,19 +611,17 @@ void ima_post_path_mknod(struct dentry *dentry)
 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 {
        /*
-        * READING_FIRMWARE_PREALLOC_BUFFER
-        *
         * Do devices using pre-allocated memory run the risk of the
         * firmware being accessible to the device prior to the completion
         * of IMA's signature verification any more than when using two
-        * buffers?
+        * buffers? It may be desirable to include the buffer address
+        * in this API and walk all the dma_map_single() mappings to check.
         */
        return 0;
 }
 
 const int read_idmap[READING_MAX_ID] = {
        [READING_FIRMWARE] = FIRMWARE_CHECK,
-       [READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK,
        [READING_MODULE] = MODULE_CHECK,
        [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
        [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,