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umh: creds: convert call_usermodehelper_keys() to use subprocess_info->init()

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call_usermodehelper_keys() uses call_usermodehelper_setkeys() to change
subprocess_info->cred in advance.  Now that we have info->init() we can
change this code to set tgcred->session_keyring in context of execing
kernel thread.

Note: since currently call_usermodehelper_keys() is never called with
UMH_NO_WAIT, call_usermodehelper_keys()->key_get() and umh_keys_cleanup()
are not really needed, we could rely on install_session_keyring_to_cred()
which does key_get() on success.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2010-05-26 14:43:00 -07:00 committed by Linus Torvalds
parent 898b374af6
commit 685bfd2c48
5 changed files with 34 additions and 37 deletions
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17
include/linux/kmod.h
View file

@ -72,8 +72,6 @@ struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
char **envp, gfp_t gfp_mask);
/* Set various pieces of state into the subprocess_info structure */
void call_usermodehelper_setkeys(struct subprocess_info *info,
struct key *session_keyring);
void call_usermodehelper_setfns(struct subprocess_info *info,
int (*init)(struct subprocess_info *info),
void (*cleanup)(struct subprocess_info *info),
@ -112,21 +110,6 @@ call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait)
NULL, NULL, NULL);
}
static inline int
call_usermodehelper_keys(char *path, char **argv, char **envp,
struct key *session_keyring, enum umh_wait wait)
{
struct subprocess_info *info;
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
if (info == NULL)
return -ENOMEM;
call_usermodehelper_setkeys(info, session_keyring);
return call_usermodehelper_exec(info, wait);
}
extern void usermodehelper_init(void);
extern int usermodehelper_disable(void);

18
kernel/kmod.c
View file

@ -366,24 +366,6 @@ struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
}
EXPORT_SYMBOL(call_usermodehelper_setup);
/**
* call_usermodehelper_setkeys - set the session keys for usermode helper
* @info: a subprocess_info returned by call_usermodehelper_setup
* @session_keyring: the session keyring for the process
*/
void call_usermodehelper_setkeys(struct subprocess_info *info,
struct key *session_keyring)
{
#ifdef CONFIG_KEYS
struct thread_group_cred *tgcred = info->cred->tgcred;
key_put(tgcred->session_keyring);
tgcred->session_keyring = key_get(session_keyring);
#else
BUG();
#endif
}
EXPORT_SYMBOL(call_usermodehelper_setkeys);
/**
* call_usermodehelper_setfns - set a cleanup/init function
* @info: a subprocess_info returned by call_usermodehelper_setup

1
security/keys/internal.h
View file

@ -124,6 +124,7 @@ extern struct key *find_keyring_by_name(const char *name, bool skip_perm_check);
extern int install_user_keyrings(void);
extern int install_thread_keyring_to_cred(struct cred *);
extern int install_process_keyring_to_cred(struct cred *);
extern int install_session_keyring_to_cred(struct cred *, struct key *);
extern struct key *request_key_and_link(struct key_type *type,
const char *description,

3
security/keys/process_keys.c
View file

@ -216,8 +216,7 @@ static int install_process_keyring(void)
/*
* install a session keyring directly to a credentials struct
*/
static int install_session_keyring_to_cred(struct cred *cred,
struct key *keyring)
int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
{
unsigned long flags;
struct key *old;

32
security/keys/request_key.c
View file

@ -58,6 +58,38 @@ void complete_request_key(struct key_construction *cons, int error)
}
EXPORT_SYMBOL(complete_request_key);
static int umh_keys_init(struct subprocess_info *info)
{
struct cred *cred = (struct cred*)current_cred();
struct key *keyring = info->data;
/*
* This is called in context of freshly forked kthread before
* kernel_execve(), we can just change our ->session_keyring.
*/
return install_session_keyring_to_cred(cred, keyring);
}
static void umh_keys_cleanup(struct subprocess_info *info)
{
struct key *keyring = info->data;
key_put(keyring);
}
static int call_usermodehelper_keys(char *path, char **argv, char **envp,
struct key *session_keyring, enum umh_wait wait)
{
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
struct subprocess_info *info =
call_usermodehelper_setup(path, argv, envp, gfp_mask);
if (!info)
return -ENOMEM;
call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
key_get(session_keyring));
return call_usermodehelper_exec(info, wait);
}
/*
* request userspace finish the construction of a key
* - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"