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sysctl changes for 6.11-rc1

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Summary
 
 * Remove "->procname == NULL" check when iterating through sysctl table arrays
 
     Removing sentinels in ctl_table arrays reduces the build time size and
     runtime memory consumed by ~64 bytes per array. With all ctl_table
     sentinels gone, the additional check for ->procname == NULL that worked in
     tandem with the ARRAY_SIZE to calculate the size of the ctl_table arrays is
     no longer needed and has been removed. The sysctl register functions now
     returns an error if a sentinel is used.
 
 * Preparation patches for sysctl constification
 
     Constifying ctl_table structs prevents the modification of proc_handler
     function pointers as they would reside in .rodata. The ctl_table arguments
     in sysctl utility functions are const qualified in preparation for a future
     treewide proc_handler argument constification commit.
 
 * Misc fixes
 
     Increase robustness of set_ownership by providing sane default ownership
     values in case the callee doesn't set them. Bound check proc_dou8vec_minmax
     to avoid loading buggy modules and give sysctl testing module a name to
     avoid compiler complaints.
 
 Testing
 
   * This got push to linux-next in v6.10-rc2, so it has had more than a month
     of testing
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Merge tag 'sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl

Pull sysctl updates from Joel Granados:

 - Remove "->procname == NULL" check when iterating through sysctl table
   arrays

   Removing sentinels in ctl_table arrays reduces the build time size
   and runtime memory consumed by ~64 bytes per array. With all
   ctl_table sentinels gone, the additional check for ->procname == NULL
   that worked in tandem with the ARRAY_SIZE to calculate the size of
   the ctl_table arrays is no longer needed and has been removed. The
   sysctl register functions now returns an error if a sentinel is used.

 - Preparation patches for sysctl constification

   Constifying ctl_table structs prevents the modification of
   proc_handler function pointers as they would reside in .rodata. The
   ctl_table arguments in sysctl utility functions are const qualified
   in preparation for a future treewide proc_handler argument
   constification commit.

 - Misc fixes

   Increase robustness of set_ownership by providing sane default
   ownership values in case the callee doesn't set them. Bound check
   proc_dou8vec_minmax to avoid loading buggy modules and give sysctl
   testing module a name to avoid compiler complaints.

* tag 'sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
  sysctl: Warn on an empty procname element
  sysctl: Remove ctl_table sentinel code comments
  sysctl: Remove "child" sysctl code comments
  sysctl: Remove superfluous empty allocations from sysctl internals
  sysctl: Replace nr_entries with ctl_table_size in new_links
  sysctl: Remove check for sentinel element in ctl_table arrays
  mm profiling: Remove superfluous sentinel element from ctl_table
  locking: Remove superfluous sentinel element from kern_lockdep_table
  sysctl: Add module description to sysctl-testing
  sysctl: constify ctl_table arguments of utility function
  utsname: constify ctl_table arguments of utility function
  sysctl: move the extra1/2 boundary check of u8 to sysctl_check_table_array
  sysctl: always initialize i_uid/i_gid
This commit is contained in:
Linus Torvalds 2024-07-16 14:24:29 -07:00
commit f8a8b94d06
8 changed files with 105 additions and 63 deletions
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64
fs/proc/proc_sysctl.c
View File

@ -21,7 +21,7 @@
#define list_for_each_table_entry(entry, header) \
entry = header->ctl_table; \
for (size_t i = 0 ; i < header->ctl_table_size && entry->procname; ++i, entry++)
for (size_t i = 0 ; i < header->ctl_table_size; ++i, entry++)
static const struct dentry_operations proc_sys_dentry_operations;
static const struct file_operations proc_sys_file_operations;
@ -476,12 +476,10 @@ static struct inode *proc_sys_make_inode(struct super_block *sb,
make_empty_dir_inode(inode);
}
if (root->set_ownership)
root->set_ownership(head, &inode->i_uid, &inode->i_gid);
else {
inode->i_uid = GLOBAL_ROOT_UID;
inode->i_gid = GLOBAL_ROOT_GID;
}
if (root->set_ownership)
root->set_ownership(head, &inode->i_uid, &inode->i_gid);
return inode;
}
@ -951,14 +949,14 @@ static struct ctl_dir *new_dir(struct ctl_table_set *set,
char *new_name;
new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
sizeof(struct ctl_table)*2 + namelen + 1,
sizeof(struct ctl_table) + namelen + 1,
GFP_KERNEL);
if (!new)
return NULL;
node = (struct ctl_node *)(new + 1);
table = (struct ctl_table *)(node + 1);
new_name = (char *)(table + 2);
new_name = (char *)(table + 1);
memcpy(new_name, name, namelen);
table[0].procname = new_name;
table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
@ -1093,6 +1091,7 @@ static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
static int sysctl_check_table_array(const char *path, struct ctl_table *table)
{
unsigned int extra;
int err = 0;
if ((table->proc_handler == proc_douintvec) ||
@ -1104,6 +1103,19 @@ static int sysctl_check_table_array(const char *path, struct ctl_table *table)
if (table->proc_handler == proc_dou8vec_minmax) {
if (table->maxlen != sizeof(u8))
err |= sysctl_err(path, table, "array not allowed");
if (table->extra1) {
extra = *(unsigned int *) table->extra1;
if (extra > 255U)
err |= sysctl_err(path, table,
"range value too large for proc_dou8vec_minmax");
}
if (table->extra2) {
extra = *(unsigned int *) table->extra2;
if (extra > 255U)
err |= sysctl_err(path, table,
"range value too large for proc_dou8vec_minmax");
}
}
if (table->proc_handler == proc_dobool) {
@ -1119,6 +1131,8 @@ static int sysctl_check_table(const char *path, struct ctl_table_header *header)
struct ctl_table *entry;
int err = 0;
list_for_each_table_entry(entry, header) {
if (!entry->procname)
err |= sysctl_err(path, entry, "procname is null");
if ((entry->proc_handler == proc_dostring) ||
(entry->proc_handler == proc_dobool) ||
(entry->proc_handler == proc_dointvec) ||
@ -1154,18 +1168,16 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_
struct ctl_table_header *links;
struct ctl_node *node;
char *link_name;
int nr_entries, name_bytes;
int name_bytes;
name_bytes = 0;
nr_entries = 0;
list_for_each_table_entry(entry, head) {
nr_entries++;
name_bytes += strlen(entry->procname) + 1;
}
links = kzalloc(sizeof(struct ctl_table_header) +
sizeof(struct ctl_node)*nr_entries +
sizeof(struct ctl_table)*(nr_entries + 1) +
sizeof(struct ctl_node)*head->ctl_table_size +
sizeof(struct ctl_table)*head->ctl_table_size +
name_bytes,
GFP_KERNEL);
@ -1173,8 +1185,8 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_
return NULL;
node = (struct ctl_node *)(links + 1);
link_table = (struct ctl_table *)(node + nr_entries);
link_name = (char *)&link_table[nr_entries + 1];
link_table = (struct ctl_table *)(node + head->ctl_table_size);
link_name = (char *)(link_table + head->ctl_table_size);
link = link_table;
list_for_each_table_entry(entry, head) {
@ -1188,7 +1200,7 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_
}
init_header(links, dir->header.root, dir->header.set, node, link_table,
head->ctl_table_size);
links->nreg = nr_entries;
links->nreg = head->ctl_table_size;
return links;
}
@ -1300,28 +1312,23 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
* __register_sysctl_table - register a leaf sysctl table
* @set: Sysctl tree to register on
* @path: The path to the directory the sysctl table is in.
* @table: the top-level table structure without any child. This table
* should not be free'd after registration. So it should not be
* used on stack. It can either be a global or dynamically allocated
* by the caller and free'd later after sysctl unregistration.
*
* @table: the top-level table structure. This table should not be free'd
* after registration. So it should not be used on stack. It can either
* be a global or dynamically allocated by the caller and free'd later
* after sysctl unregistration.
* @table_size : The number of elements in table
*
* Register a sysctl table hierarchy. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
* array.
*
* The members of the &struct ctl_table structure are used as follows:
*
* procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
* enter a sysctl file
*
* data - a pointer to data for use by proc_handler
*
* maxlen - the maximum size in bytes of the data
*
* mode - the file permissions for the /proc/sys file
*
* child - must be %NULL.
*
* type - Defines the target type (described in struct definition)
* proc_handler - the text handler routine (described below)
*
* extra1, extra2 - extra pointers usable by the proc handler routines
@ -1329,8 +1336,7 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
* [0] https://lkml.kernel.org/87zgpte9o4.fsf@email.froward.int.ebiederm.org
*
* Leaf nodes in the sysctl tree will be represented by a single file
* under /proc; non-leaf nodes (where child is not NULL) are not allowed,
* sysctl_check_table() verifies this.
* under /proc; non-leaf nodes are not allowed.
*
* There must be a proc_handler routine for any terminal nodes.
* Several default handlers are available to cover common cases -

2
include/linux/sysctl.h
View File

@ -237,7 +237,7 @@ extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
void do_sysctl_args(void);
bool sysctl_is_alias(char *param);
int do_proc_douintvec(struct ctl_table *table, int write,
int do_proc_douintvec(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos,
int (*conv)(unsigned long *lvalp,
unsigned int *valp,

1
kernel/locking/lockdep.c
View File

@ -97,7 +97,6 @@ static struct ctl_table kern_lockdep_table[] = {
.proc_handler = proc_dointvec,
},
#endif /* CONFIG_LOCK_STAT */
{ }
};
static __init int kernel_lockdep_sysctls_init(void)

50
kernel/sysctl-test.c
View File

@ -367,6 +367,54 @@ static void sysctl_test_api_dointvec_write_single_greater_int_max(
KUNIT_EXPECT_EQ(test, 0, *((int *)table.data));
}
/*
* Test that registering an invalid extra value is not allowed.
*/
static void sysctl_test_register_sysctl_sz_invalid_extra_value(
struct kunit *test)
{
unsigned char data = 0;
struct ctl_table table_foo[] = {
{
.procname = "foo",
.data = &data,
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
.extra1 = SYSCTL_FOUR,
.extra2 = SYSCTL_ONE_THOUSAND,
},
};
struct ctl_table table_bar[] = {
{
.procname = "bar",
.data = &data,
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
.extra1 = SYSCTL_NEG_ONE,
.extra2 = SYSCTL_ONE_HUNDRED,
},
};
struct ctl_table table_qux[] = {
{
.procname = "qux",
.data = &data,
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_TWO_HUNDRED,
},
};
KUNIT_EXPECT_NULL(test, register_sysctl("foo", table_foo));
KUNIT_EXPECT_NULL(test, register_sysctl("foo", table_bar));
KUNIT_EXPECT_NOT_NULL(test, register_sysctl("foo", table_qux));
}
static struct kunit_case sysctl_test_cases[] = {
KUNIT_CASE(sysctl_test_api_dointvec_null_tbl_data),
KUNIT_CASE(sysctl_test_api_dointvec_table_maxlen_unset),
@ -378,6 +426,7 @@ static struct kunit_case sysctl_test_cases[] = {
KUNIT_CASE(sysctl_test_dointvec_write_happy_single_negative),
KUNIT_CASE(sysctl_test_api_dointvec_write_single_less_int_min),
KUNIT_CASE(sysctl_test_api_dointvec_write_single_greater_int_max),
KUNIT_CASE(sysctl_test_register_sysctl_sz_invalid_extra_value),
{}
};
@ -388,4 +437,5 @@ static struct kunit_suite sysctl_test_suite = {
kunit_test_suites(&sysctl_test_suite);
MODULE_DESCRIPTION("KUnit test of proc sysctl");
MODULE_LICENSE("GPL v2");

31
kernel/sysctl.c
View File

@ -205,7 +205,7 @@ static int _proc_do_string(char *data, int maxlen, int write,
return 0;
}
static void warn_sysctl_write(struct ctl_table *table)
static void warn_sysctl_write(const struct ctl_table *table)
{
pr_warn_once("%s wrote to %s when file position was not 0!\n"
"This will not be supported in the future. To silence this\n"
@ -223,7 +223,7 @@ static void warn_sysctl_write(struct ctl_table *table)
* handlers can ignore the return value.
*/
static bool proc_first_pos_non_zero_ignore(loff_t *ppos,
struct ctl_table *table)
const struct ctl_table *table)
{
if (!*ppos)
return false;
@ -468,7 +468,7 @@ static int do_proc_douintvec_conv(unsigned long *lvalp,
static const char proc_wspace_sep[] = { ' ', '\t', '\n' };
static int __do_proc_dointvec(void *tbl_data, struct ctl_table *table,
static int __do_proc_dointvec(void *tbl_data, const struct ctl_table *table,
int write, void *buffer,
size_t *lenp, loff_t *ppos,
int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
@ -541,7 +541,7 @@ out:
return err;
}
static int do_proc_dointvec(struct ctl_table *table, int write,
static int do_proc_dointvec(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos,
int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
int write, void *data),
@ -552,7 +552,7 @@ static int do_proc_dointvec(struct ctl_table *table, int write,
}
static int do_proc_douintvec_w(unsigned int *tbl_data,
struct ctl_table *table,
const struct ctl_table *table,
void *buffer,
size_t *lenp, loff_t *ppos,
int (*conv)(unsigned long *lvalp,
@ -639,7 +639,7 @@ out:
return err;
}
static int __do_proc_douintvec(void *tbl_data, struct ctl_table *table,
static int __do_proc_douintvec(void *tbl_data, const struct ctl_table *table,
int write, void *buffer,
size_t *lenp, loff_t *ppos,
int (*conv)(unsigned long *lvalp,
@ -675,7 +675,7 @@ static int __do_proc_douintvec(void *tbl_data, struct ctl_table *table,
return do_proc_douintvec_r(i, buffer, lenp, ppos, conv, data);
}
int do_proc_douintvec(struct ctl_table *table, int write,
int do_proc_douintvec(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos,
int (*conv)(unsigned long *lvalp,
unsigned int *valp,
@ -977,16 +977,10 @@ int proc_dou8vec_minmax(struct ctl_table *table, int write,
if (table->maxlen != sizeof(u8))
return -EINVAL;
if (table->extra1) {
if (table->extra1)
min = *(unsigned int *) table->extra1;
if (min > 255U)
return -EINVAL;
}
if (table->extra2) {
if (table->extra2)
max = *(unsigned int *) table->extra2;
if (max > 255U)
return -EINVAL;
}
tmp = *table;
@ -1023,8 +1017,9 @@ static int sysrq_sysctl_handler(struct ctl_table *table, int write,
}
#endif
static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table,
int write, void *buffer, size_t *lenp, loff_t *ppos,
static int __do_proc_doulongvec_minmax(void *data,
const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos,
unsigned long convmul, unsigned long convdiv)
{
unsigned long *i, *min, *max;
@ -1096,7 +1091,7 @@ out:
return err;
}
static int do_proc_doulongvec_minmax(struct ctl_table *table, int write,
static int do_proc_doulongvec_minmax(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos, unsigned long convmul,
unsigned long convdiv)
{

2
kernel/utsname_sysctl.c
View File

@ -15,7 +15,7 @@
#ifdef CONFIG_PROC_SYSCTL
static void *get_uts(struct ctl_table *table)
static void *get_uts(const struct ctl_table *table)
{
char *which = table->data;
struct uts_namespace *uts_ns;

1
lib/alloc_tag.c
View File

@ -239,7 +239,6 @@ static struct ctl_table memory_allocation_profiling_sysctls[] = {
#endif
.proc_handler = proc_do_static_key,
},
{ }
};
static void __init sysctl_init(void)

11
net/sysctl_net.c
View File

@ -127,7 +127,7 @@ static void ensure_safe_net_sysctl(struct net *net, const char *path,
pr_debug("Registering net sysctl (net %p): %s\n", net, path);
ent = table;
for (size_t i = 0; i < table_size && ent->procname; ent++, i++) {
for (size_t i = 0; i < table_size; ent++, i++) {
unsigned long addr;
const char *where;
@ -165,17 +165,10 @@ struct ctl_table_header *register_net_sysctl_sz(struct net *net,
struct ctl_table *table,
size_t table_size)
{
int count;
struct ctl_table *entry;
if (!net_eq(net, &init_net))
ensure_safe_net_sysctl(net, path, table, table_size);
entry = table;
for (count = 0 ; count < table_size && entry->procname; entry++, count++)
;
return __register_sysctl_table(&net->sysctls, path, table, count);
return __register_sysctl_table(&net->sysctls, path, table, table_size);
}
EXPORT_SYMBOL_GPL(register_net_sysctl_sz);