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sysctl: Add support for register sysctl tables with a normal cstring path.

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Make __register_sysctl_table the core sysctl registration operation and
make it take a char * string as path.

Now that binary paths have been banished into the real of backwards
compatibility in kernel/binary_sysctl.c where they can be safely
ignored there is no longer a need to use struct ctl_path to represent
path names when registering ctl_tables.

Start the transition to using normal char * strings to represent
pathnames when registering sysctl tables.  Normal strings are easier
to deal with both in the internal sysctl implementation and for
programmers registering sysctl tables.

__register_sysctl_paths is turned into a backwards compatibility wrapper
that converts a ctl_path array into a normal char * string.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2012-01-21 10:26:26 -08:00
parent f05e53a7fb
commit 6e9d516415
2 changed files with 87 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

94
fs/proc/proc_sysctl.c
View File

@ -882,7 +882,7 @@ static int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *tabl
#endif /* CONFIG_SYSCTL_SYSCALL_CHECK */
/**
* __register_sysctl_paths - register a sysctl hierarchy
* __register_sysctl_table - register a sysctl table
* @root: List of sysctl headers to register on
* @namespaces: Data to compute which lists of sysctl entries are visible
* @path: The path to the directory the sysctl table is in.
@ -934,21 +934,34 @@ static int sysctl_check_table(struct nsproxy *namespaces, struct ctl_table *tabl
* This routine returns %NULL on a failure to register, and a pointer
* to the table header on success.
*/
struct ctl_table_header *__register_sysctl_paths(
struct ctl_table_header *__register_sysctl_table(
struct ctl_table_root *root,
struct nsproxy *namespaces,
const struct ctl_path *path, struct ctl_table *table)
const char *path, struct ctl_table *table)
{
struct ctl_table_header *header;
struct ctl_table *new, **prevp;
unsigned int n, npath;
const char *name, *nextname;
unsigned int npath = 0;
struct ctl_table_set *set;
size_t path_bytes = 0;
char *new_name;
/* Count the path components */
for (npath = 0; path[npath].procname; ++npath)
path_bytes += strlen(path[npath].procname) + 1;
for (name = path; name; name = nextname) {
int namelen;
nextname = strchr(name, '/');
if (nextname) {
namelen = nextname - name;
nextname++;
} else {
namelen = strlen(name);
}
if (namelen == 0)
continue;
path_bytes += namelen + 1;
npath++;
}
/*
* For each path component, allocate a 2-element ctl_table array.
@ -968,9 +981,20 @@ struct ctl_table_header *__register_sysctl_paths(
/* Now connect the dots */
prevp = &header->ctl_table;
for (n = 0; n < npath; ++n, ++path) {
/* Copy the procname */
strcpy(new_name, path->procname);
for (name = path; name; name = nextname) {
int namelen;
nextname = strchr(name, '/');
if (nextname) {
namelen = nextname - name;
nextname++;
} else {
namelen = strlen(name);
}
if (namelen == 0)
continue;
memcpy(new_name, name, namelen);
new_name[namelen] = '\0';
new->procname = new_name;
new->mode = 0555;
@ -978,7 +1002,7 @@ struct ctl_table_header *__register_sysctl_paths(
prevp = &new->child;
new += 2;
new_name += strlen(new_name) + 1;
new_name += namelen + 1;
}
*prevp = table;
header->ctl_table_arg = table;
@ -1022,6 +1046,56 @@ struct ctl_table_header *__register_sysctl_paths(
return header;
}
static char *append_path(const char *path, char *pos, const char *name)
{
int namelen;
namelen = strlen(name);
if (((pos - path) + namelen + 2) >= PATH_MAX)
return NULL;
memcpy(pos, name, namelen);
pos[namelen] = '/';
pos[namelen + 1] = '\0';
pos += namelen + 1;
return pos;
}
/**
* __register_sysctl_paths - register a sysctl table hierarchy
* @root: List of sysctl headers to register on
* @namespaces: Data to compute which lists of sysctl entries are visible
* @path: The path to the directory the sysctl table is in.
* @table: the top-level table structure
*
* Register a sysctl table hierarchy. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* See __register_sysctl_table for more details.
*/
struct ctl_table_header *__register_sysctl_paths(
struct ctl_table_root *root,
struct nsproxy *namespaces,
const struct ctl_path *path, struct ctl_table *table)
{
struct ctl_table_header *header = NULL;
const struct ctl_path *component;
char *new_path, *pos;
pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
if (!new_path)
return NULL;
pos[0] = '\0';
for (component = path; component->procname; component++) {
pos = append_path(new_path, pos, component->procname);
if (!pos)
goto out;
}
header = __register_sysctl_table(root, namespaces, new_path, table);
out:
kfree(new_path);
return header;
}
/**
* register_sysctl_table_path - register a sysctl table hierarchy
* @path: The path to the directory the sysctl table is in.

3
include/linux/sysctl.h
View File

@ -1073,6 +1073,9 @@ extern void setup_sysctl_set(struct ctl_table_set *p,
extern void retire_sysctl_set(struct ctl_table_set *set);
void register_sysctl_root(struct ctl_table_root *root);
struct ctl_table_header *__register_sysctl_table(
struct ctl_table_root *root, struct nsproxy *namespaces,
const char *path, struct ctl_table *table);
struct ctl_table_header *__register_sysctl_paths(
struct ctl_table_root *root, struct nsproxy *namespaces,
const struct ctl_path *path, struct ctl_table *table);