[PATCH v4 09/11] FIT: fit_open: make filename handling more robust

[Marco Felsch <m.felsch@pengutronix.de>]

To make the filename handling more robust we need to resolve any
possible link to get an abosulte path. Furthermore the filename shall be
absolut, e.g. must start with the root '/'.

This is in preparation of adding cached fit_open support.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
 common/image-fit.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/common/image-fit.c b/common/image-fit.c
index 0067f46e60bc954b418aef3398e2c10856b41c02..1cb407d4d86cb3d0a643149bb08c46caadcd56fe 100644
--- a/common/image-fit.c
+++ b/common/image-fit.c
@@ -972,12 +972,25 @@ struct fit_handle *fit_open_buf(const void *buf, size_t size, bool verbose,
  *
  * Return: A handle to a FIT image or a ERR_PTR
  */
-struct fit_handle *fit_open(const char *filename, bool verbose,
+struct fit_handle *fit_open(const char *_filename, bool verbose,
 			    enum bootm_verify verify, loff_t max_size)
 {
 	struct fit_handle *handle;
+	char *filename;
 	int ret;
 
+	if (*_filename != '/') {
+		pr_err("The FIT filename must start with '/'\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* dirfd is ignored, since _filename is absolute */
+	filename = canonicalize_path(AT_FDCWD, _filename);
+	if (!filename) {
+		pr_err("Failed to resolve %s with %s\n", _filename, strerror(errno));
+		return ERR_PTR(-errno);
+	}
+
 	handle = xzalloc(sizeof(struct fit_handle));
 
 	handle->verbose = verbose;
@@ -988,9 +1001,12 @@ struct fit_handle *fit_open(const char *filename, bool verbose,
 	if (ret && ret != -EFBIG) {
 		pr_err("unable to read %s: %pe\n", filename, ERR_PTR(ret));
 		free(handle);
+		free(filename);
 		return ERR_PTR(ret);
 	}
 
+	free(filename);
+
 	handle->fit = handle->fit_alloc;
 
 	ret = fit_do_open(handle);

-- 
2.39.5