diff options
| -rw-r--r-- | include/linux/kmod.h | 3 | ||||
| -rw-r--r-- | kernel/kmod.c | 100 | ||||
| -rw-r--r-- | kernel/sysctl.c | 6 |
3 files changed, 109 insertions, 0 deletions
diff --git a/include/linux/kmod.h b/include/linux/kmod.h index 6efd7a7..79bb98d 100644 --- a/include/linux/kmod.h +++ b/include/linux/kmod.h @@ -24,6 +24,7 @@ #include <linux/errno.h> #include <linux/compiler.h> #include <linux/workqueue.h> +#include <linux/sysctl.h> #define KMOD_PATH_LEN 256 @@ -109,6 +110,8 @@ call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait) NULL, NULL, NULL); } +extern struct ctl_table usermodehelper_table[]; + extern void usermodehelper_init(void); extern int usermodehelper_disable(void); diff --git a/kernel/kmod.c b/kernel/kmod.c index 9cd0591..06fdea2 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -25,6 +25,7 @@ #include <linux/kmod.h> #include <linux/slab.h> #include <linux/completion.h> +#include <linux/cred.h> #include <linux/file.h> #include <linux/fdtable.h> #include <linux/workqueue.h> @@ -43,6 +44,13 @@ extern int max_threads; static struct workqueue_struct *khelper_wq; +#define CAP_BSET (void *)1 +#define CAP_PI (void *)2 + +static kernel_cap_t usermodehelper_bset = CAP_FULL_SET; +static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET; +static DEFINE_SPINLOCK(umh_sysctl_lock); + #ifdef CONFIG_MODULES /* @@ -132,6 +140,7 @@ EXPORT_SYMBOL(__request_module); static int ____call_usermodehelper(void *data) { struct subprocess_info *sub_info = data; + struct cred *new; int retval; spin_lock_irq(¤t->sighand->siglock); @@ -153,6 +162,19 @@ static int ____call_usermodehelper(void *data) goto fail; } + retval = -ENOMEM; + new = prepare_kernel_cred(current); + if (!new) + goto fail; + + spin_lock(&umh_sysctl_lock); + new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset); + new->cap_inheritable = cap_intersect(usermodehelper_inheritable, + new->cap_inheritable); + spin_unlock(&umh_sysctl_lock); + + commit_creds(new); + retval = kernel_execve(sub_info->path, (const char *const *)sub_info->argv, (const char *const *)sub_info->envp); @@ -418,6 +440,84 @@ unlock: } EXPORT_SYMBOL(call_usermodehelper_exec); +static int proc_cap_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + struct ctl_table t; + unsigned long cap_array[_KERNEL_CAPABILITY_U32S]; + kernel_cap_t new_cap; + int err, i; + + if (write && (!capable(CAP_SETPCAP) || + !capable(CAP_SYS_MODULE))) + return -EPERM; + + /* + * convert from the global kernel_cap_t to the ulong array to print to + * userspace if this is a read. + */ + spin_lock(&umh_sysctl_lock); + for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) { + if (table->data == CAP_BSET) + cap_array[i] = usermodehelper_bset.cap[i]; + else if (table->data == CAP_PI) + cap_array[i] = usermodehelper_inheritable.cap[i]; + else + BUG(); + } + spin_unlock(&umh_sysctl_lock); + + t = *table; + t.data = &cap_array; + + /* + * actually read or write and array of ulongs from userspace. Remember + * these are least significant 32 bits first + */ + err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos); + if (err < 0) + return err; + + /* + * convert from the sysctl array of ulongs to the kernel_cap_t + * internal representation + */ + for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) + new_cap.cap[i] = cap_array[i]; + + /* + * Drop everything not in the new_cap (but don't add things) + */ + spin_lock(&umh_sysctl_lock); + if (write) { + if (table->data == CAP_BSET) + usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap); + if (table->data == CAP_PI) + usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap); + } + spin_unlock(&umh_sysctl_lock); + + return 0; +} + +struct ctl_table usermodehelper_table[] = { + { + .procname = "bset", + .data = CAP_BSET, + .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), + .mode = 0600, + .proc_handler = proc_cap_handler, + }, + { + .procname = "inheritable", + .data = CAP_PI, + .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long), + .mode = 0600, + .proc_handler = proc_cap_handler, + }, + { } +}; + void __init usermodehelper_init(void) { khelper_wq = create_singlethread_workqueue("khelper"); diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c0bb324..965134b 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -56,6 +56,7 @@ #include <linux/kprobes.h> #include <linux/pipe_fs_i.h> #include <linux/oom.h> +#include <linux/kmod.h> #include <asm/uaccess.h> #include <asm/processor.h> @@ -616,6 +617,11 @@ static struct ctl_table kern_table[] = { .child = random_table, }, { + .procname = "usermodehelper", + .mode = 0555, + .child = usermodehelper_table, + }, + { .procname = "overflowuid", .data = &overflowuid, .maxlen = sizeof(int), |
