git: 6c9506559080 - main - Escape any '.' characters in sysctl node names

[Ronald Klop]

On 7/22/21 6:23 PM, Alan Somers wrote:
> The branch main has been updated by asomers:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=6c9506559080da2914749bf611225d7c0a153609
> 
> commit 6c9506559080da2914749bf611225d7c0a153609
> Author:     Alan Somers <asomers at FreeBSD.org>
> AuthorDate: 2021-07-21 21:11:00 +0000
> Commit:     Alan Somers <asomers at FreeBSD.org>
> CommitDate: 2021-07-22 16:22:48 +0000
> 
>      Escape any '.' characters in sysctl node names
>      
>      ZFS creates some sysctl nodes that include a pool name, and '.' is an
>      allowed character in pool names.  But it's the separator in the sysctl
>      tree, so it can't be included in a sysctl name.  Replace it with "%25".
>      Handily, "%" is illegal in ZFS pool names, so there's no ambiguity
>      there.


Hi,

Wouldn't it be cleaner to enumerate the pools as numbers/ids and put the name of the pool in a field as the data instead of the key?

Regards,
Ronald.



>      PR:             257316
>      MFC after:      3 weeks
>      Sponsored by:   Axcient
>      Reviewed by:    freqlabs
>      Differential Revision: https://reviews.freebsd.org/D31265
> ---
>   sys/kern/kern_sysctl.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 46 insertions(+), 2 deletions(-)
> 
> diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
> index e46584758c9b..c472db18aac7 100644
> --- a/sys/kern/kern_sysctl.c
> +++ b/sys/kern/kern_sysctl.c
> @@ -122,6 +122,7 @@ static int sysctl_root(SYSCTL_HANDLER_ARGS);
>   /* Root list */
>   struct sysctl_oid_list sysctl__children = SLIST_HEAD_INITIALIZER(&sysctl__children);
>   
> +static char*	sysctl_escape_name(const char*);
>   static int	sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del,
>   		    int recurse);
>   static int	sysctl_old_kernel(struct sysctl_req *, const void *, size_t);
> @@ -747,6 +748,46 @@ sysctl_remove_name(struct sysctl_oid *parent, const char *name,
>   	return (error);
>   }
>   
> +/*
> + * Duplicate the provided string, escaping any illegal characters.  The result
> + * must be freed when no longer in use.
> + *
> + * The list of illegal characters is ".".
> + */
> +static char*
> +sysctl_escape_name(const char* orig)
> +{
> +	int i, s = 0, d = 0, nillegals = 0;
> +	char *new;
> +
> +	/* First count the number of illegal characters */
> +	for (i = 0; orig[i] != '\0'; i++) {
> +		if (orig[i] == '.')
> +			nillegals++;
> +	}
> +
> +	/* Allocate storage for new string */
> +	new = malloc(i + 2 * nillegals + 1, M_SYSCTLOID, M_WAITOK);
> +
> +	/* Copy the name, escaping characters as we go */
> +	while (orig[s] != '\0') {
> +		if (orig[s] == '.') {
> +			/* %25 is the hexadecimal representation of '.' */
> +			new[d++] = '%';
> +			new[d++] = '2';
> +			new[d++] = '5';
> +			s++;
> +		} else {
> +			new[d++] = orig[s++];
> +		}
> +	}
> +
> +	/* Finally, nul-terminate */
> +	new[d] = '\0';
> +
> +	return (new);
> +}
> +
>   static int
>   sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del, int recurse)
>   {
> @@ -828,14 +869,17 @@ sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
>   	const char *label)
>   {
>   	struct sysctl_oid *oidp;
> +	char *escaped;
>   
>   	/* You have to hook up somewhere.. */
>   	if (parent == NULL)
>   		return(NULL);
> +	escaped = sysctl_escape_name(name);
>   	/* Check if the node already exists, otherwise create it */
>   	SYSCTL_WLOCK();
> -	oidp = sysctl_find_oidname(name, parent);
> +	oidp = sysctl_find_oidname(escaped, parent);
>   	if (oidp != NULL) {
> +		free(escaped, M_SYSCTLOID);
>   		if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
>   			oidp->oid_refcnt++;
>   			/* Update the context */
> @@ -854,7 +898,7 @@ sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
>   	SLIST_INIT(&oidp->oid_children);
>   	oidp->oid_number = number;
>   	oidp->oid_refcnt = 1;
> -	oidp->oid_name = strdup(name, M_SYSCTLOID);
> +	oidp->oid_name = escaped;
>   	oidp->oid_handler = handler;
>   	oidp->oid_kind = CTLFLAG_DYN | kind;
>   	oidp->oid_arg1 = arg1;
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