[lustre-devel] [PATCH 1/8] lustre: seq: make seq_proc_write_common() safer

[NeilBrown <neilb@suse.com>]

On Wed, Jul 24 2019, James Simmons wrote:

> From: Andreas Dilger <adilger@whamcloud.com>
>
> Don't allow seq_proc_write_common() to specify arbitrary ranges,
> since this can permanently corrupt the sequence controller and/or
> sequnece server.  That would allow duplicate FID allocation, or
> possibly prevent any new files to be created or servers to be added
> to the filesystem.
>
> Instead, limit the sequence range that can be written via /proc to
> a subset of the sequence range currently allocated to that node.
> Add the "clear" keyword to allow dropping the entire local sequence
> and force a new one to be fetched from the sequence server.
>
> WC-bug-id: https://jira.whamcloud.com/browse/LU-3642
> Lustre-commit: 05f69f5ee20eeffcc26f643333cedcfb53ba6669
> Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
> Reviewed-on: http://review.whamcloud.com/7123
> Reviewed-by: Jinshan Xiong <jinshan.xiong@gmail.com>
> Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
> Reviewed-by: James Simmons <uja.ornl@gmail.com>
> Reviewed-by: Oleg Drokin <green@whamclould.com>
> ---
>  fs/lustre/fid/lproc_fid.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)

I already have this is my backport branch.
 a8ab6db57383

NeilBrown


>
> diff --git a/fs/lustre/fid/lproc_fid.c b/fs/lustre/fid/lproc_fid.c
> index 94869d4..e2e47df 100644
> --- a/fs/lustre/fid/lproc_fid.c
> +++ b/fs/lustre/fid/lproc_fid.c
> @@ -52,14 +52,18 @@
>  /* Format: [0x64BIT_INT - 0x64BIT_INT] + 32 bytes just in case */
>  #define MAX_FID_RANGE_STRLEN (32 + 2 * 2 * sizeof(u64))
>  /*
> - * Note: this function is only used for testing, it is no safe for production
> - * use.
> + * Reduce the SEQ range allocated to a node to a strict subset of the range
> + * currently-allocated SEQ range.  If the specified range is "clear", then
> + * drop all allocated sequences and request a new one from the master.
> + *
> + * Note: this function should only be used for testing, it is not necessarily
> + * safe for production use.
>   */
>  static int
>  ldebugfs_fid_write_common(const char __user *buffer, size_t count,
>  			  struct lu_seq_range *range)
>  {
> -	struct lu_seq_range tmp;
> +	struct lu_seq_range tmp = { 0, };
>  	int rc;
>  	char kernbuf[MAX_FID_RANGE_STRLEN];
>  
> @@ -82,8 +86,6 @@
>  	rc = sscanf(kernbuf, "[%llx - %llx]\n",
>  		    (unsigned long long *)&tmp.lsr_start,
>  		    (unsigned long long *)&tmp.lsr_end);
> -	if (rc != 2)
> -		return -EINVAL;
>  	if (!lu_seq_range_is_sane(&tmp) || lu_seq_range_is_zero(&tmp) ||
>  	    tmp.lsr_start < range->lsr_start || tmp.lsr_end > range->lsr_end)
>  		return -EINVAL;
> -- 
> 1.8.3.1
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