[U-Boot] [RFC 1/3] fs: fat: cannot write to subdirectories

[Lukasz Majewski]

On Sat, 26 May 2018 10:34:45 +0200
Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:

> fs_fat_write() is not able to write to subdirectories.
> 
> Currently if a filepath with a leading slash is passed, the slash is
> treated as part of the filename to be created in the root directory.
> 
> Strip leading (back-)slashes.
> 
> Check that the remaining filename does not contain any illegal
> characters (<>:"/\|?*). This way we will throw an error when trying
> to write to a subdirectory.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
>  fs/fat/fat_write.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
> index 5ca8fcda73c..f32745febb4 100644
> --- a/fs/fat/fat_write.c
> +++ b/fs/fat/fat_write.c
> @@ -908,9 +908,11 @@ static int do_fat_write(const char *filename,
> void *buffer, loff_t size, volume_info volinfo;
>  	fsdata datablock;
>  	fsdata *mydata = &datablock;
> -	int cursect;
> +	int cursect, i;
>  	int ret = -1, name_len;
>  	char l_filename[VFAT_MAXLEN_BYTES];
> +	char bad[2] = " ";
> +	const char illegal[] = "<>:\"/\\|?*";
>  
>  	*actwrite = size;
>  	dir_curclust = 0;
> @@ -970,6 +972,20 @@ static int do_fat_write(const char *filename,
> void *buffer, loff_t size, }
>  	dentptr = (dir_entry *) do_fat_read_at_block;
>  
> +	/* Strip leading (back-)slashes */
> +	while (*filename == '/')
> +		++filename;
> +	while (*filename == '\\')
> +		++filename;
> +	/* Check that the filename is valid */
> +	for (i = 0; i < strlen(illegal); ++i) {
> +		*bad = illegal[i];
> +		if (strstr(filename, bad)) {
> +			printf("FAT: illegal filename (%s)\n",
> filename);
> +			return -1;
> +		}
> +	}
> +
>  	name_len = strlen(filename);
>  	if (name_len >= VFAT_MAXLEN_BYTES)
>  		name_len = VFAT_MAXLEN_BYTES - 1;

Reviewed-by: Lukasz Majewski <lukma at denx.de>


Best regards,

Lukasz Majewski

--

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