| Message ID | 20250107230438.GC30633@strace.io (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | ptrace: introduce PTRACE_SET_SYSCALL_INFO API | expand |
"Dmitry V. Levin" <ldv@strace.io> writes: > Similar to syscall_set_arguments() that complements > syscall_get_arguments(), introduce syscall_set_nr() > that complements syscall_get_nr(). > > syscall_set_nr() is going to be needed along with > syscall_set_arguments() on all HAVE_ARCH_TRACEHOOK > architectures to implement PTRACE_SET_SYSCALL_INFO API. > > Signed-off-by: Dmitry V. Levin <ldv@strace.io> > --- > arch/arc/include/asm/syscall.h | 6 ++++++ > arch/arm/include/asm/syscall.h | 12 ++++++++++++ > arch/arm64/include/asm/syscall.h | 7 +++++++ > arch/hexagon/include/asm/syscall.h | 7 +++++++ > arch/loongarch/include/asm/syscall.h | 7 +++++++ > arch/m68k/include/asm/syscall.h | 7 +++++++ > arch/microblaze/include/asm/syscall.h | 7 +++++++ > arch/mips/include/asm/syscall.h | 7 +++++++ > arch/nios2/include/asm/syscall.h | 5 +++++ > arch/openrisc/include/asm/syscall.h | 6 ++++++ > arch/parisc/include/asm/syscall.h | 7 +++++++ > arch/powerpc/include/asm/syscall.h | 5 +++++ > arch/riscv/include/asm/syscall.h | 7 +++++++ > arch/s390/include/asm/syscall.h | 7 +++++++ > arch/sh/include/asm/syscall_32.h | 7 +++++++ > arch/sparc/include/asm/syscall.h | 7 +++++++ > arch/um/include/asm/syscall-generic.h | 5 +++++ > arch/x86/include/asm/syscall.h | 7 +++++++ > arch/xtensa/include/asm/syscall.h | 7 +++++++ > include/asm-generic/syscall.h | 14 ++++++++++++++ > 20 files changed, 144 insertions(+) > > diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h > index b3dd883699e7..1c0e349fd5c9 100644 > --- a/arch/s390/include/asm/syscall.h > +++ b/arch/s390/include/asm/syscall.h > @@ -24,6 +24,13 @@ static inline long syscall_get_nr(struct task_struct *task, > (regs->int_code & 0xffff) : -1; > } > > +static inline void syscall_set_nr(struct task_struct *task, > + struct pt_regs *regs, > + int nr) > +{ I think there should be a if (!test_pt_regs_flags(regs, PIF_SYSCALL)) return; before the modification so a user can't accidentally change int_code when ptrace stopped in a non-syscall path. > + regs->int_code = (regs->int_code & ~0xffff) | (nr & 0xffff); > +} > + > static inline void syscall_rollback(struct task_struct *task, > struct pt_regs *regs) > {
On Fri, Jan 10, 2025 at 08:37:46AM +0100, Sven Schnelle wrote: > "Dmitry V. Levin" <ldv@strace.io> writes: > > > Similar to syscall_set_arguments() that complements > > syscall_get_arguments(), introduce syscall_set_nr() > > that complements syscall_get_nr(). > > > > syscall_set_nr() is going to be needed along with > > syscall_set_arguments() on all HAVE_ARCH_TRACEHOOK > > architectures to implement PTRACE_SET_SYSCALL_INFO API. [...] > > diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h > > index b3dd883699e7..1c0e349fd5c9 100644 > > --- a/arch/s390/include/asm/syscall.h > > +++ b/arch/s390/include/asm/syscall.h > > @@ -24,6 +24,13 @@ static inline long syscall_get_nr(struct task_struct *task, > > (regs->int_code & 0xffff) : -1; > > } > > > > +static inline void syscall_set_nr(struct task_struct *task, > > + struct pt_regs *regs, > > + int nr) > > +{ > > I think there should be a > > if (!test_pt_regs_flags(regs, PIF_SYSCALL)) > return; > > before the modification so a user can't accidentally change int_code > when ptrace stopped in a non-syscall path. The reason why syscall_get_nr() has this check on s390 (and similar checks on arc, powerpc, and sparc) is that syscall_get_nr() can be called while the target task is not in syscall. Unlike syscall_get_nr(), syscall_set_nr() can be called only when the target task is stopped for tracing on entering syscall: the description in include/asm-generic/syscall.h explicitly states that, and the follow-up patch that introduces PTRACE_SET_SYSCALL_INFO adds a syscall_set_nr() call when the tracee is stopped on entering syscall in either PTRACE_SYSCALL_INFO_ENTRY or PTRACE_SYSCALL_INFO_SECCOMP state. I don't mind adding a check, but syscall_set_nr() invocation while the target task is not in syscall wouldn't be a result of user actions but a kernel programing error, and in that case WARN_ON_ONCE() would be more appropriate. If calling syscall_set_nr() while the target task is not in syscall was legal, then syscall_set_nr() would have been designed to return a value indicating the status of operation. Anyway, I'll add an explanatory comment to syscall_set_nr() on all architectures where syscall_get_nr() has a check.
diff --git a/arch/arc/include/asm/syscall.h b/arch/arc/include/asm/syscall.h index 89c1e1736356..6095fbfa74ab 100644 --- a/arch/arc/include/asm/syscall.h +++ b/arch/arc/include/asm/syscall.h @@ -23,6 +23,12 @@ syscall_get_nr(struct task_struct *task, struct pt_regs *regs) return -1; } +static inline void +syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr) +{ + regs->r8 = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h index 21927fa0ae2b..cfa61f355675 100644 --- a/arch/arm/include/asm/syscall.h +++ b/arch/arm/include/asm/syscall.h @@ -31,6 +31,18 @@ static inline int syscall_get_nr(struct task_struct *task, return task_thread_info(task)->abi_syscall & __NR_SYSCALL_MASK; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + if (!IS_ENABLED(CONFIG_AEABI) || IS_ENABLED(CONFIG_OABI_COMPAT)) { + if (nr != -1) + nr &= __NR_SYSCALL_MASK; + } + + task_thread_info(task)->abi_syscall = nr; +} + static inline bool __in_oabi_syscall(struct task_struct *task) { return IS_ENABLED(CONFIG_OABI_COMPAT) && diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index 76020b66286b..0e6807618bed 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -23,6 +23,13 @@ static inline int syscall_get_nr(struct task_struct *task, return regs->syscallno; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->syscallno = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/hexagon/include/asm/syscall.h b/arch/hexagon/include/asm/syscall.h index 12d2df6aaa03..72befa719434 100644 --- a/arch/hexagon/include/asm/syscall.h +++ b/arch/hexagon/include/asm/syscall.h @@ -26,6 +26,13 @@ static inline long syscall_get_nr(struct task_struct *task, return regs->r06; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->r06 = nr; +} + static inline void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, unsigned long *args) diff --git a/arch/loongarch/include/asm/syscall.h b/arch/loongarch/include/asm/syscall.h index ff415b3c0a8e..81d2733f7b94 100644 --- a/arch/loongarch/include/asm/syscall.h +++ b/arch/loongarch/include/asm/syscall.h @@ -26,6 +26,13 @@ static inline long syscall_get_nr(struct task_struct *task, return regs->regs[11]; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->regs[11] = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/m68k/include/asm/syscall.h b/arch/m68k/include/asm/syscall.h index d1453e850cdd..bf84b160c2eb 100644 --- a/arch/m68k/include/asm/syscall.h +++ b/arch/m68k/include/asm/syscall.h @@ -14,6 +14,13 @@ static inline int syscall_get_nr(struct task_struct *task, return regs->orig_d0; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->orig_d0 = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/microblaze/include/asm/syscall.h b/arch/microblaze/include/asm/syscall.h index 5eb3f624cc59..b5b6b91fae3e 100644 --- a/arch/microblaze/include/asm/syscall.h +++ b/arch/microblaze/include/asm/syscall.h @@ -14,6 +14,13 @@ static inline long syscall_get_nr(struct task_struct *task, return regs->r12; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->r12 = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h index b8a19e465bf4..793026c4c7f0 100644 --- a/arch/mips/include/asm/syscall.h +++ b/arch/mips/include/asm/syscall.h @@ -41,6 +41,13 @@ static inline long syscall_get_nr(struct task_struct *task, return task_thread_info(task)->syscall; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + task_thread_info(task)->syscall = nr; +} + static inline void mips_syscall_update_nr(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/nios2/include/asm/syscall.h b/arch/nios2/include/asm/syscall.h index 526449edd768..8e3eb1d689bb 100644 --- a/arch/nios2/include/asm/syscall.h +++ b/arch/nios2/include/asm/syscall.h @@ -15,6 +15,11 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) return regs->r2; } +static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr) +{ + regs->r2 = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/openrisc/include/asm/syscall.h b/arch/openrisc/include/asm/syscall.h index e6383be2a195..5e037d9659c5 100644 --- a/arch/openrisc/include/asm/syscall.h +++ b/arch/openrisc/include/asm/syscall.h @@ -25,6 +25,12 @@ syscall_get_nr(struct task_struct *task, struct pt_regs *regs) return regs->orig_gpr11; } +static inline void +syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr) +{ + regs->orig_gpr11 = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/parisc/include/asm/syscall.h b/arch/parisc/include/asm/syscall.h index b146d0ae4c77..c11222798ab2 100644 --- a/arch/parisc/include/asm/syscall.h +++ b/arch/parisc/include/asm/syscall.h @@ -17,6 +17,13 @@ static inline long syscall_get_nr(struct task_struct *tsk, return regs->gr[20]; } +static inline void syscall_set_nr(struct task_struct *tsk, + struct pt_regs *regs, + int nr) +{ + regs->gr[20] = nr; +} + static inline void syscall_get_arguments(struct task_struct *tsk, struct pt_regs *regs, unsigned long *args) diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h index b2715448a660..09e34d19c961 100644 --- a/arch/powerpc/include/asm/syscall.h +++ b/arch/powerpc/include/asm/syscall.h @@ -39,6 +39,11 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) return -1; } +static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr) +{ + regs->gpr[0] = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h index 8d389ba995c8..a5281cdf2b10 100644 --- a/arch/riscv/include/asm/syscall.h +++ b/arch/riscv/include/asm/syscall.h @@ -30,6 +30,13 @@ static inline int syscall_get_nr(struct task_struct *task, return regs->a7; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->a7 = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h index b3dd883699e7..1c0e349fd5c9 100644 --- a/arch/s390/include/asm/syscall.h +++ b/arch/s390/include/asm/syscall.h @@ -24,6 +24,13 @@ static inline long syscall_get_nr(struct task_struct *task, (regs->int_code & 0xffff) : -1; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->int_code = (regs->int_code & ~0xffff) | (nr & 0xffff); +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/sh/include/asm/syscall_32.h b/arch/sh/include/asm/syscall_32.h index cb51a7528384..0e1e7b029457 100644 --- a/arch/sh/include/asm/syscall_32.h +++ b/arch/sh/include/asm/syscall_32.h @@ -15,6 +15,13 @@ static inline long syscall_get_nr(struct task_struct *task, return (regs->tra >= 0) ? regs->regs[3] : -1L; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->regs[3] = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/sparc/include/asm/syscall.h b/arch/sparc/include/asm/syscall.h index 62a5a78804c4..36830a37fda4 100644 --- a/arch/sparc/include/asm/syscall.h +++ b/arch/sparc/include/asm/syscall.h @@ -25,6 +25,13 @@ static inline long syscall_get_nr(struct task_struct *task, return (syscall_p ? regs->u_regs[UREG_G1] : -1L); } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->u_regs[UREG_G1] = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h index 2984feb9d576..bcd73bcfe577 100644 --- a/arch/um/include/asm/syscall-generic.h +++ b/arch/um/include/asm/syscall-generic.h @@ -21,6 +21,11 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) return PT_REGS_SYSCALL_NR(regs); } +static inline void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr) +{ + PT_REGS_SYSCALL_NR(regs) = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h index b9c249dd9e3d..c10dbb74cd00 100644 --- a/arch/x86/include/asm/syscall.h +++ b/arch/x86/include/asm/syscall.h @@ -38,6 +38,13 @@ static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) return regs->orig_ax; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->orig_ax = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/xtensa/include/asm/syscall.h b/arch/xtensa/include/asm/syscall.h index f9a671cbf933..7db3b489c8ad 100644 --- a/arch/xtensa/include/asm/syscall.h +++ b/arch/xtensa/include/asm/syscall.h @@ -28,6 +28,13 @@ static inline long syscall_get_nr(struct task_struct *task, return regs->syscall; } +static inline void syscall_set_nr(struct task_struct *task, + struct pt_regs *regs, + int nr) +{ + regs->syscall = nr; +} + static inline void syscall_rollback(struct task_struct *task, struct pt_regs *regs) { diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h index 0f7b9a493de7..e33fd4e783c1 100644 --- a/include/asm-generic/syscall.h +++ b/include/asm-generic/syscall.h @@ -37,6 +37,20 @@ struct pt_regs; */ int syscall_get_nr(struct task_struct *task, struct pt_regs *regs); +/** + * syscall_set_nr - change the system call a task is executing + * @task: task of interest, must be blocked + * @regs: task_pt_regs() of @task + * @nr: system call number + * + * Changes the system call number @task is about to execute. + * + * It's only valid to call this when @task is stopped for tracing on + * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or + * %SYSCALL_WORK_SYSCALL_AUDIT. + */ +void syscall_set_nr(struct task_struct *task, struct pt_regs *regs, int nr); + /** * syscall_rollback - roll back registers after an aborted system call * @task: task of interest, must be in system call exit tracing
Similar to syscall_set_arguments() that complements syscall_get_arguments(), introduce syscall_set_nr() that complements syscall_get_nr(). syscall_set_nr() is going to be needed along with syscall_set_arguments() on all HAVE_ARCH_TRACEHOOK architectures to implement PTRACE_SET_SYSCALL_INFO API. Signed-off-by: Dmitry V. Levin <ldv@strace.io> --- arch/arc/include/asm/syscall.h | 6 ++++++ arch/arm/include/asm/syscall.h | 12 ++++++++++++ arch/arm64/include/asm/syscall.h | 7 +++++++ arch/hexagon/include/asm/syscall.h | 7 +++++++ arch/loongarch/include/asm/syscall.h | 7 +++++++ arch/m68k/include/asm/syscall.h | 7 +++++++ arch/microblaze/include/asm/syscall.h | 7 +++++++ arch/mips/include/asm/syscall.h | 7 +++++++ arch/nios2/include/asm/syscall.h | 5 +++++ arch/openrisc/include/asm/syscall.h | 6 ++++++ arch/parisc/include/asm/syscall.h | 7 +++++++ arch/powerpc/include/asm/syscall.h | 5 +++++ arch/riscv/include/asm/syscall.h | 7 +++++++ arch/s390/include/asm/syscall.h | 7 +++++++ arch/sh/include/asm/syscall_32.h | 7 +++++++ arch/sparc/include/asm/syscall.h | 7 +++++++ arch/um/include/asm/syscall-generic.h | 5 +++++ arch/x86/include/asm/syscall.h | 7 +++++++ arch/xtensa/include/asm/syscall.h | 7 +++++++ include/asm-generic/syscall.h | 14 ++++++++++++++ 20 files changed, 144 insertions(+)