diff options
Diffstat (limited to 'kernel/ptrace.c')
-rw-r--r-- | kernel/ptrace.c | 78 |
1 files changed, 47 insertions, 31 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 656476eedb1..5f33cdb6fff 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -7,6 +7,7 @@ * to continually duplicate across every architecture. */ +#include <linux/capability.h> #include <linux/module.h> #include <linux/sched.h> #include <linux/errno.h> @@ -408,54 +409,62 @@ int ptrace_request(struct task_struct *child, long request, return ret; } -#ifndef __ARCH_SYS_PTRACE -static int ptrace_get_task_struct(long request, long pid, - struct task_struct **childp) +/** + * ptrace_traceme -- helper for PTRACE_TRACEME + * + * Performs checks and sets PT_PTRACED. + * Should be used by all ptrace implementations for PTRACE_TRACEME. + */ +int ptrace_traceme(void) { - struct task_struct *child; int ret; /* - * Callers use child == NULL as an indication to exit early even - * when the return value is 0, so make sure it is non-NULL here. + * Are we already being traced? + */ + if (current->ptrace & PT_PTRACED) + return -EPERM; + ret = security_ptrace(current->parent, current); + if (ret) + return -EPERM; + /* + * Set the ptrace bit in the process ptrace flags. */ - *childp = NULL; + current->ptrace |= PT_PTRACED; + return 0; +} - if (request == PTRACE_TRACEME) { - /* - * Are we already being traced? - */ - if (current->ptrace & PT_PTRACED) - return -EPERM; - ret = security_ptrace(current->parent, current); - if (ret) - return -EPERM; - /* - * Set the ptrace bit in the process ptrace flags. - */ - current->ptrace |= PT_PTRACED; - return 0; - } +/** + * ptrace_get_task_struct -- grab a task struct reference for ptrace + * @pid: process id to grab a task_struct reference of + * + * This function is a helper for ptrace implementations. It checks + * permissions and then grabs a task struct for use of the actual + * ptrace implementation. + * + * Returns the task_struct for @pid or an ERR_PTR() on failure. + */ +struct task_struct *ptrace_get_task_struct(pid_t pid) +{ + struct task_struct *child; /* - * You may not mess with init + * Tracing init is not allowed. */ if (pid == 1) - return -EPERM; + return ERR_PTR(-EPERM); - ret = -ESRCH; read_lock(&tasklist_lock); child = find_task_by_pid(pid); if (child) get_task_struct(child); read_unlock(&tasklist_lock); if (!child) - return -ESRCH; - - *childp = child; - return 0; + return ERR_PTR(-ESRCH); + return child; } +#ifndef __ARCH_SYS_PTRACE asmlinkage long sys_ptrace(long request, long pid, long addr, long data) { struct task_struct *child; @@ -465,9 +474,16 @@ asmlinkage long sys_ptrace(long request, long pid, long addr, long data) * This lock_kernel fixes a subtle race with suid exec */ lock_kernel(); - ret = ptrace_get_task_struct(request, pid, &child); - if (!child) + if (request == PTRACE_TRACEME) { + ret = ptrace_traceme(); goto out; + } + + child = ptrace_get_task_struct(pid); + if (IS_ERR(child)) { + ret = PTR_ERR(child); + goto out; + } if (request == PTRACE_ATTACH) { ret = ptrace_attach(child); |