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author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2016-11-07 22:26:35 +0100 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-04-04 15:17:15 +0200 |
commit | 631b7abacd02b88f4b0795c08b54ad4fc3e7c7c0 (patch) | |
tree | b014cc81ce32ca7e3fb05bf5d90d35737fa56cc2 /lib | |
parent | Linux 5.1-rc3 (diff) | |
download | linux-631b7abacd02b88f4b0795c08b54ad4fc3e7c7c0.tar.xz linux-631b7abacd02b88f4b0795c08b54ad4fc3e7c7c0.zip |
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.c | 57 |
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; |