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proc: Make inline name size calculation automatic

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Make calculation of the size of the inline name in struct proc_dir_entry
automatic, rather than having to manually encode the numbers and failing to
allow for lockdep.

Require a minimum inline name size of 33+1 to allow for names that look
like two hex numbers with a dash between.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2018-06-13 19:43:19 +01:00 committed by Al Viro
parent de52cf922a
commit 24074a35c5
4 changed files with 16 additions and 12 deletions
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2
fs/proc/generic.c
View file

@ -410,7 +410,7 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
if (!ent)
goto out;
if (qstr.len + 1 <= sizeof(ent->inline_name)) {
if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) {
ent->name = ent->inline_name;
} else {
ent->name = kmalloc(qstr.len + 1, GFP_KERNEL);

5
fs/proc/inode.c
View file

@ -105,9 +105,8 @@ void __init proc_init_kmemcache(void)
kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
SLAB_ACCOUNT|SLAB_PANIC, NULL);
proc_dir_entry_cache = kmem_cache_create_usercopy(
"proc_dir_entry", sizeof(struct proc_dir_entry), 0, SLAB_PANIC,
offsetof(struct proc_dir_entry, inline_name),
sizeof_field(struct proc_dir_entry, inline_name), NULL);
"proc_dir_entry", SIZEOF_PDE_SLOT, 0, SLAB_PANIC,
OFFSETOF_PDE_NAME, SIZEOF_PDE_INLINE_NAME, NULL);
}
static int proc_show_options(struct seq_file *seq, struct dentry *root)

18
fs/proc/internal.h
View file

@ -62,14 +62,20 @@ struct proc_dir_entry {
char *name;
umode_t mode;
u8 namelen;
#ifdef CONFIG_64BIT
#define SIZEOF_PDE_INLINE_NAME (192-155)
#else
#define SIZEOF_PDE_INLINE_NAME (128-95)
#endif
char inline_name[SIZEOF_PDE_INLINE_NAME];
char inline_name[];
} __randomize_layout;
#define OFFSETOF_PDE_NAME offsetof(struct proc_dir_entry, inline_name)
#define SIZEOF_PDE_SLOT \
(OFFSETOF_PDE_NAME + 34 <= 64 ? 64 : \
OFFSETOF_PDE_NAME + 34 <= 128 ? 128 : \
OFFSETOF_PDE_NAME + 34 <= 192 ? 192 : \
OFFSETOF_PDE_NAME + 34 <= 256 ? 256 : \
OFFSETOF_PDE_NAME + 34 <= 512 ? 512 : \
0)
#define SIZEOF_PDE_INLINE_NAME (SIZEOF_PDE_SLOT - OFFSETOF_PDE_NAME)
extern struct kmem_cache *proc_dir_entry_cache;
void pde_free(struct proc_dir_entry *pde);

3
fs/proc/root.c
View file

@ -204,8 +204,7 @@ struct proc_dir_entry proc_root = {
.proc_fops = &proc_root_operations,
.parent = &proc_root,
.subdir = RB_ROOT,
.name = proc_root.inline_name,
.inline_name = "/proc",
.name = "/proc",
};
int pid_ns_prepare_proc(struct pid_namespace *ns)