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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2016-11-07 16:26:35 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2019-04-04 09:17:15 -0400
commit631b7abacd02b88f4b0795c08b54ad4fc3e7c7c0 (patch)
treeb014cc81ce32ca7e3fb05bf5d90d35737fa56cc2 /lib
parent79a3aaa7b82e3106be97842dedfd8429248896e6 (diff)
downloadlinux-stericsson-631b7abacd02b88f4b0795c08b54ad4fc3e7c7c0.tar.gz
ptrace: Remove maxargs from task_current_syscall()
task_current_syscall() has a single user that passes in 6 for maxargs, which is the maximum arguments that can be used to get system calls from syscall_get_arguments(). Instead of passing in a number of arguments to grab, just get 6 arguments. The args argument even specifies that it's an array of 6 items. This will also allow changing syscall_get_arguments() to not get a variable number of arguments, but always grab 6. Linus also suggested not passing in a bunch of arguments to task_current_syscall() but to instead pass in a pointer to a structure, and just fill the structure. struct seccomp_data has almost all the parameters that is needed except for the stack pointer (sp). As seccomp_data is part of uapi, and I'm afraid to change it, a new structure was created "syscall_info", which includes seccomp_data and adds the "sp" field. Link: http://lkml.kernel.org/r/20161107213233.466776454@goodmis.org Cc: Andy Lutomirski <luto@kernel.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/syscall.c57
1 files changed, 25 insertions, 32 deletions
diff --git a/lib/syscall.c b/lib/syscall.c
index 1a7077f20eae..e8467e17b9a2 100644
--- a/lib/syscall.c
+++ b/lib/syscall.c
@@ -5,16 +5,14 @@
#include <linux/export.h>
#include <asm/syscall.h>
-static int collect_syscall(struct task_struct *target, long *callno,
- unsigned long args[6], unsigned int maxargs,
- unsigned long *sp, unsigned long *pc)
+static int collect_syscall(struct task_struct *target, struct syscall_info *info)
{
struct pt_regs *regs;
if (!try_get_task_stack(target)) {
/* Task has no stack, so the task isn't in a syscall. */
- *sp = *pc = 0;
- *callno = -1;
+ memset(info, 0, sizeof(*info));
+ info->data.nr = -1;
return 0;
}
@@ -24,12 +22,13 @@ static int collect_syscall(struct task_struct *target, long *callno,
return -EAGAIN;
}
- *sp = user_stack_pointer(regs);
- *pc = instruction_pointer(regs);
+ info->sp = user_stack_pointer(regs);
+ info->data.instruction_pointer = instruction_pointer(regs);
- *callno = syscall_get_nr(target, regs);
- if (*callno != -1L && maxargs > 0)
- syscall_get_arguments(target, regs, 0, maxargs, args);
+ info->data.nr = syscall_get_nr(target, regs);
+ if (info->data.nr != -1L)
+ syscall_get_arguments(target, regs, 0, 6,
+ (unsigned long *)&info->data.args[0]);
put_task_stack(target);
return 0;
@@ -38,41 +37,35 @@ static int collect_syscall(struct task_struct *target, long *callno,
/**
* task_current_syscall - Discover what a blocked task is doing.
* @target: thread to examine
- * @callno: filled with system call number or -1
- * @args: filled with @maxargs system call arguments
- * @maxargs: number of elements in @args to fill
- * @sp: filled with user stack pointer
- * @pc: filled with user PC
+ * @info: structure with the following fields:
+ * .sp - filled with user stack pointer
+ * .data.nr - filled with system call number or -1
+ * .data.args - filled with @maxargs system call arguments
+ * .data.instruction_pointer - filled with user PC
*
- * If @target is blocked in a system call, returns zero with *@callno
- * set to the the call's number and @args filled in with its arguments.
- * Registers not used for system call arguments may not be available and
- * it is not kosher to use &struct user_regset calls while the system
+ * If @target is blocked in a system call, returns zero with @info.data.nr
+ * set to the the call's number and @info.data.args filled in with its
+ * arguments. Registers not used for system call arguments may not be available
+ * and it is not kosher to use &struct user_regset calls while the system
* call is still in progress. Note we may get this result if @target
* has finished its system call but not yet returned to user mode, such
* as when it's stopped for signal handling or syscall exit tracing.
*
* If @target is blocked in the kernel during a fault or exception,
- * returns zero with *@callno set to -1 and does not fill in @args.
- * If so, it's now safe to examine @target using &struct user_regset
- * get() calls as long as we're sure @target won't return to user mode.
+ * returns zero with *@info.data.nr set to -1 and does not fill in
+ * @info.data.args. If so, it's now safe to examine @target using
+ * &struct user_regset get() calls as long as we're sure @target won't return
+ * to user mode.
*
* Returns -%EAGAIN if @target does not remain blocked.
- *
- * Returns -%EINVAL if @maxargs is too large (maximum is six).
*/
-int task_current_syscall(struct task_struct *target, long *callno,
- unsigned long args[6], unsigned int maxargs,
- unsigned long *sp, unsigned long *pc)
+int task_current_syscall(struct task_struct *target, struct syscall_info *info)
{
long state;
unsigned long ncsw;
- if (unlikely(maxargs > 6))
- return -EINVAL;
-
if (target == current)
- return collect_syscall(target, callno, args, maxargs, sp, pc);
+ return collect_syscall(target, info);
state = target->state;
if (unlikely(!state))
@@ -80,7 +73,7 @@ int task_current_syscall(struct task_struct *target, long *callno,
ncsw = wait_task_inactive(target, state);
if (unlikely(!ncsw) ||
- unlikely(collect_syscall(target, callno, args, maxargs, sp, pc)) ||
+ unlikely(collect_syscall(target, info)) ||
unlikely(wait_task_inactive(target, state) != ncsw))
return -EAGAIN;