diff options
| -rw-r--r-- | Documentation/admin-guide/syscall-user-dispatch.rst | 4 | ||||
| -rw-r--r-- | include/linux/syscall_user_dispatch.h | 18 | ||||
| -rw-r--r-- | include/uapi/linux/ptrace.h | 30 | ||||
| -rw-r--r-- | kernel/entry/syscall_user_dispatch.c | 74 | ||||
| -rw-r--r-- | kernel/ptrace.c | 9 | ||||
| -rw-r--r-- | tools/testing/selftests/ptrace/.gitignore | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/ptrace/Makefile | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/ptrace/get_set_sud.c | 72 |
8 files changed, 200 insertions, 10 deletions
diff --git a/Documentation/admin-guide/syscall-user-dispatch.rst b/Documentation/admin-guide/syscall-user-dispatch.rst index 60314953c728..e3cfffef5a63 100644 --- a/Documentation/admin-guide/syscall-user-dispatch.rst +++ b/Documentation/admin-guide/syscall-user-dispatch.rst @@ -73,6 +73,10 @@ thread-wide, without the need to invoke the kernel directly. selector can be set to SYSCALL_DISPATCH_FILTER_ALLOW or SYSCALL_DISPATCH_FILTER_BLOCK. Any other value should terminate the program with a SIGSYS. +Additionally, a tasks syscall user dispatch configuration can be peeked +and poked via the PTRACE_(GET|SET)_SYSCALL_USER_DISPATCH_CONFIG ptrace +requests. This is useful for checkpoint/restart software. + Security Notes -------------- diff --git a/include/linux/syscall_user_dispatch.h b/include/linux/syscall_user_dispatch.h index a0ae443fb7df..641ca8880995 100644 --- a/include/linux/syscall_user_dispatch.h +++ b/include/linux/syscall_user_dispatch.h @@ -22,6 +22,12 @@ int set_syscall_user_dispatch(unsigned long mode, unsigned long offset, #define clear_syscall_work_syscall_user_dispatch(tsk) \ clear_task_syscall_work(tsk, SYSCALL_USER_DISPATCH) +int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size, + void __user *data); + +int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size, + void __user *data); + #else struct syscall_user_dispatch {}; @@ -35,6 +41,18 @@ static inline void clear_syscall_work_syscall_user_dispatch(struct task_struct * { } +static inline int syscall_user_dispatch_get_config(struct task_struct *task, + unsigned long size, void __user *data) +{ + return -EINVAL; +} + +static inline int syscall_user_dispatch_set_config(struct task_struct *task, + unsigned long size, void __user *data) +{ + return -EINVAL; +} + #endif /* CONFIG_GENERIC_ENTRY */ #endif /* _SYSCALL_USER_DISPATCH_H */ diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h index 195ae64a8c87..72c038fc71d0 100644 --- a/include/uapi/linux/ptrace.h +++ b/include/uapi/linux/ptrace.h @@ -112,6 +112,36 @@ struct ptrace_rseq_configuration { __u32 pad; }; +#define PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG 0x4210 +#define PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG 0x4211 + +/* + * struct ptrace_sud_config - Per-task configuration for Syscall User Dispatch + * @mode: One of PR_SYS_DISPATCH_ON or PR_SYS_DISPATCH_OFF + * @selector: Tracees user virtual address of SUD selector + * @offset: SUD exclusion area (virtual address) + * @len: Length of SUD exclusion area + * + * Used to get/set the syscall user dispatch configuration for a tracee. + * Selector is optional (may be NULL), and if invalid will produce + * a SIGSEGV in the tracee upon first access. + * + * If mode is PR_SYS_DISPATCH_ON, syscall dispatch will be enabled. If + * PR_SYS_DISPATCH_OFF, syscall dispatch will be disabled and all other + * parameters must be 0. The value in *selector (if not null), also determines + * whether syscall dispatch will occur. + * + * The Syscall User Dispatch Exclusion area described by offset/len is the + * virtual address space from which syscalls will not produce a user + * dispatch. + */ +struct ptrace_sud_config { + __u64 mode; + __u64 selector; + __u64 offset; + __u64 len; +}; + /* * These values are stored in task->ptrace_message * by ptrace_stop to describe the current syscall-stop. diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c index 0b6379adff6b..5340c5aa89e7 100644 --- a/kernel/entry/syscall_user_dispatch.c +++ b/kernel/entry/syscall_user_dispatch.c @@ -4,6 +4,7 @@ */ #include <linux/sched.h> #include <linux/prctl.h> +#include <linux/ptrace.h> #include <linux/syscall_user_dispatch.h> #include <linux/uaccess.h> #include <linux/signal.h> @@ -68,8 +69,9 @@ bool syscall_user_dispatch(struct pt_regs *regs) return true; } -int set_syscall_user_dispatch(unsigned long mode, unsigned long offset, - unsigned long len, char __user *selector) +static int task_set_syscall_user_dispatch(struct task_struct *task, unsigned long mode, + unsigned long offset, unsigned long len, + char __user *selector) { switch (mode) { case PR_SYS_DISPATCH_OFF: @@ -86,7 +88,16 @@ int set_syscall_user_dispatch(unsigned long mode, unsigned long offset, if (offset && offset + len <= offset) return -EINVAL; - if (selector && !access_ok(selector, sizeof(*selector))) + /* + * access_ok() will clear memory tags for tagged addresses + * if current has memory tagging enabled. + + * To enable a tracer to set a tracees selector the + * selector address must be untagged for access_ok(), + * otherwise an untagged tracer will always fail to set a + * tagged tracees selector. + */ + if (selector && !access_ok(untagged_addr(selector), sizeof(*selector))) return -EFAULT; break; @@ -94,15 +105,60 @@ int set_syscall_user_dispatch(unsigned long mode, unsigned long offset, return -EINVAL; } - current->syscall_dispatch.selector = selector; - current->syscall_dispatch.offset = offset; - current->syscall_dispatch.len = len; - current->syscall_dispatch.on_dispatch = false; + task->syscall_dispatch.selector = selector; + task->syscall_dispatch.offset = offset; + task->syscall_dispatch.len = len; + task->syscall_dispatch.on_dispatch = false; if (mode == PR_SYS_DISPATCH_ON) - set_syscall_work(SYSCALL_USER_DISPATCH); + set_task_syscall_work(task, SYSCALL_USER_DISPATCH); + else + clear_task_syscall_work(task, SYSCALL_USER_DISPATCH); + + return 0; +} + +int set_syscall_user_dispatch(unsigned long mode, unsigned long offset, + unsigned long len, char __user *selector) +{ + return task_set_syscall_user_dispatch(current, mode, offset, len, selector); +} + +int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size, + void __user *data) +{ + struct syscall_user_dispatch *sd = &task->syscall_dispatch; + struct ptrace_sud_config cfg; + + if (size != sizeof(cfg)) + return -EINVAL; + + if (test_task_syscall_work(task, SYSCALL_USER_DISPATCH)) + cfg.mode = PR_SYS_DISPATCH_ON; else - clear_syscall_work(SYSCALL_USER_DISPATCH); + cfg.mode = PR_SYS_DISPATCH_OFF; + + cfg.offset = sd->offset; + cfg.len = sd->len; + cfg.selector = (__u64)(uintptr_t)sd->selector; + + if (copy_to_user(data, &cfg, sizeof(cfg))) + return -EFAULT; return 0; } + +int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size, + void __user *data) +{ + struct ptrace_sud_config cfg; + + if (size != sizeof(cfg)) + return -EINVAL; + + if (copy_from_user(&cfg, data, sizeof(cfg))) + return -EFAULT; + + return task_set_syscall_user_dispatch(task, cfg.mode, cfg.offset, cfg.len, + (char __user *)(uintptr_t)cfg.selector); +} diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 0786450074c1..443057bee87c 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -32,6 +32,7 @@ #include <linux/compat.h> #include <linux/sched/signal.h> #include <linux/minmax.h> +#include <linux/syscall_user_dispatch.h> #include <asm/syscall.h> /* for syscall_get_* */ @@ -1259,6 +1260,14 @@ int ptrace_request(struct task_struct *child, long request, break; #endif + case PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG: + ret = syscall_user_dispatch_set_config(child, addr, datavp); + break; + + case PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG: + ret = syscall_user_dispatch_get_config(child, addr, datavp); + break; + default: break; } diff --git a/tools/testing/selftests/ptrace/.gitignore b/tools/testing/selftests/ptrace/.gitignore index 792318aaa30c..b7dde152e75a 100644 --- a/tools/testing/selftests/ptrace/.gitignore +++ b/tools/testing/selftests/ptrace/.gitignore @@ -1,4 +1,5 @@ # SPDX-License-Identifier: GPL-2.0-only get_syscall_info +get_set_sud peeksiginfo vmaccess diff --git a/tools/testing/selftests/ptrace/Makefile b/tools/testing/selftests/ptrace/Makefile index 96ffa94afb91..1c631740a730 100644 --- a/tools/testing/selftests/ptrace/Makefile +++ b/tools/testing/selftests/ptrace/Makefile @@ -1,6 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only CFLAGS += -std=c99 -pthread -Wall $(KHDR_INCLUDES) -TEST_GEN_PROGS := get_syscall_info peeksiginfo vmaccess +TEST_GEN_PROGS := get_syscall_info peeksiginfo vmaccess get_set_sud include ../lib.mk diff --git a/tools/testing/selftests/ptrace/get_set_sud.c b/tools/testing/selftests/ptrace/get_set_sud.c new file mode 100644 index 000000000000..5297b10d25c3 --- /dev/null +++ b/tools/testing/selftests/ptrace/get_set_sud.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include "../kselftest_harness.h" +#include <stdio.h> +#include <string.h> +#include <errno.h> +#include <sys/wait.h> +#include <sys/syscall.h> +#include <sys/prctl.h> + +#include "linux/ptrace.h" + +static int sys_ptrace(int request, pid_t pid, void *addr, void *data) +{ + return syscall(SYS_ptrace, request, pid, addr, data); +} + +TEST(get_set_sud) +{ + struct ptrace_sud_config config; + pid_t child; + int ret = 0; + int status; + + child = fork(); + ASSERT_GE(child, 0); + if (child == 0) { + ASSERT_EQ(0, sys_ptrace(PTRACE_TRACEME, 0, 0, 0)) { + TH_LOG("PTRACE_TRACEME: %m"); + } + kill(getpid(), SIGSTOP); + _exit(1); + } + + waitpid(child, &status, 0); + + memset(&config, 0xff, sizeof(config)); + config.mode = PR_SYS_DISPATCH_ON; + + ret = sys_ptrace(PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG, child, + (void *)sizeof(config), &config); + + ASSERT_EQ(ret, 0); + ASSERT_EQ(config.mode, PR_SYS_DISPATCH_OFF); + ASSERT_EQ(config.selector, 0); + ASSERT_EQ(config.offset, 0); + ASSERT_EQ(config.len, 0); + + config.mode = PR_SYS_DISPATCH_ON; + config.selector = 0; + config.offset = 0x400000; + config.len = 0x1000; + + ret = sys_ptrace(PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG, child, + (void *)sizeof(config), &config); + + ASSERT_EQ(ret, 0); + + memset(&config, 1, sizeof(config)); + ret = sys_ptrace(PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG, child, + (void *)sizeof(config), &config); + + ASSERT_EQ(ret, 0); + ASSERT_EQ(config.mode, PR_SYS_DISPATCH_ON); + ASSERT_EQ(config.selector, 0); + ASSERT_EQ(config.offset, 0x400000); + ASSERT_EQ(config.len, 0x1000); + + kill(child, SIGKILL); +} + +TEST_HARNESS_MAIN |