From 7888e7ff4ee579442128d7d12a9c9dbf2cf7de6a Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 23 Jun 2005 22:00:51 -0700 Subject: [PATCH] Keys: Pass session keyring to call_usermodehelper() The attached patch makes it possible to pass a session keyring through to the process spawned by call_usermodehelper(). This allows patch 3/3 to pass an authorisation key through to /sbin/request-key, thus permitting better access controls when doing just-in-time key creation. Signed-Off-By: David Howells Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/key.h | 10 +++++++++- include/linux/kmod.h | 13 ++++++++++++- kernel/kmod.c | 17 +++++++++++++---- security/keys/request_key.c | 2 +- 4 files changed, 35 insertions(+), 7 deletions(-) diff --git a/include/linux/key.h b/include/linux/key.h index 2c24ffaca86f..2bfbf88d2740 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -273,14 +273,22 @@ extern void key_fsuid_changed(struct task_struct *tsk); extern void key_fsgid_changed(struct task_struct *tsk); extern void key_init(void); +#define __install_session_keyring(tsk, keyring) \ +({ \ + struct key *old_session = tsk->signal->session_keyring; \ + tsk->signal->session_keyring = keyring; \ + old_session; \ +}) + #else /* CONFIG_KEYS */ #define key_validate(k) 0 #define key_serial(k) 0 -#define key_get(k) NULL +#define key_get(k) ({ NULL; }) #define key_put(k) do { } while(0) #define alloc_uid_keyring(u) 0 #define switch_uid_keyring(u) do { } while(0) +#define __install_session_keyring(t, k) ({ NULL; }) #define copy_keys(f,t) 0 #define copy_thread_group_keys(t) 0 #define exit_keys(t) do { } while(0) diff --git a/include/linux/kmod.h b/include/linux/kmod.h index 95d0e4b0814d..e4a231549407 100644 --- a/include/linux/kmod.h +++ b/include/linux/kmod.h @@ -19,6 +19,7 @@ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ +#include #include #include #include @@ -34,7 +35,17 @@ static inline int request_module(const char * name, ...) { return -ENOSYS; } #endif #define try_then_request_module(x, mod...) ((x) ?: (request_module(mod), (x))) -extern int call_usermodehelper(char *path, char *argv[], char *envp[], int wait); + +struct key; +extern int call_usermodehelper_keys(char *path, char *argv[], char *envp[], + struct key *session_keyring, int wait); + +static inline int +call_usermodehelper(char *path, char **argv, char **envp, int wait) +{ + return call_usermodehelper_keys(path, argv, envp, NULL, wait); +} + extern void usermodehelper_init(void); #endif /* __LINUX_KMOD_H__ */ diff --git a/kernel/kmod.c b/kernel/kmod.c index eed53d4f5230..44166e3bb8af 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -120,6 +120,7 @@ struct subprocess_info { char *path; char **argv; char **envp; + struct key *ring; int wait; int retval; }; @@ -130,16 +131,21 @@ struct subprocess_info { static int ____call_usermodehelper(void *data) { struct subprocess_info *sub_info = data; + struct key *old_session; int retval; - /* Unblock all signals. */ + /* Unblock all signals and set the session keyring. */ + key_get(sub_info->ring); flush_signals(current); spin_lock_irq(¤t->sighand->siglock); + old_session = __install_session_keyring(current, sub_info->ring); flush_signal_handlers(current, 1); sigemptyset(¤t->blocked); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); + key_put(old_session); + /* We can run anywhere, unlike our parent keventd(). */ set_cpus_allowed(current, CPU_MASK_ALL); @@ -211,10 +217,11 @@ static void __call_usermodehelper(void *data) } /** - * call_usermodehelper - start a usermode application + * call_usermodehelper_keys - start a usermode application * @path: pathname for the application * @argv: null-terminated argument list * @envp: null-terminated environment list + * @session_keyring: session keyring for process (NULL for an empty keyring) * @wait: wait for the application to finish and return status. * * Runs a user-space application. The application is started @@ -224,7 +231,8 @@ static void __call_usermodehelper(void *data) * Must be called from process context. Returns a negative error code * if program was not execed successfully, or 0. */ -int call_usermodehelper(char *path, char **argv, char **envp, int wait) +int call_usermodehelper_keys(char *path, char **argv, char **envp, + struct key *session_keyring, int wait) { DECLARE_COMPLETION(done); struct subprocess_info sub_info = { @@ -232,6 +240,7 @@ int call_usermodehelper(char *path, char **argv, char **envp, int wait) .path = path, .argv = argv, .envp = envp, + .ring = session_keyring, .wait = wait, .retval = 0, }; @@ -247,7 +256,7 @@ int call_usermodehelper(char *path, char **argv, char **envp, int wait) wait_for_completion(&done); return sub_info.retval; } -EXPORT_SYMBOL(call_usermodehelper); +EXPORT_SYMBOL(call_usermodehelper_keys); void __init usermodehelper_init(void) { diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 1f6c0940297f..1919540f047d 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -88,7 +88,7 @@ static int call_request_key(struct key *key, argv[i] = NULL; /* do it */ - return call_usermodehelper(argv[0], argv, envp, 1); + return call_usermodehelper_keys(argv[0], argv, envp, NULL, 1); } /* end call_request_key() */ -- cgit v1.2.3-59-g8ed1b