diff options
| -rw-r--r-- | include/uapi/linux/pidfd.h | 24 | ||||
| -rw-r--r-- | kernel/pid.c | 24 | ||||
| -rw-r--r-- | kernel/signal.c | 105 | ||||
| -rw-r--r-- | tools/testing/selftests/mm/guard-pages.c | 16 | ||||
| -rw-r--r-- | tools/testing/selftests/pidfd/pidfd.h | 16 | ||||
| -rw-r--r-- | tools/testing/selftests/pidfd/pidfd_open_test.c | 6 | ||||
| -rw-r--r-- | tools/testing/selftests/pidfd/pidfd_test.c | 76 |
7 files changed, 193 insertions, 74 deletions
diff --git a/include/uapi/linux/pidfd.h b/include/uapi/linux/pidfd.h index 4540f6301b8c..e0abd0b18841 100644 --- a/include/uapi/linux/pidfd.h +++ b/include/uapi/linux/pidfd.h @@ -23,6 +23,30 @@ #define PIDFD_INFO_SIZE_VER0 64 /* sizeof first published struct */ +/* + * The concept of process and threads in userland and the kernel is a confusing + * one - within the kernel every thread is a 'task' with its own individual PID, + * however from userland's point of view threads are grouped by a single PID, + * which is that of the 'thread group leader', typically the first thread + * spawned. + * + * To cut the Gideon knot, for internal kernel usage, we refer to + * PIDFD_SELF_THREAD to refer to the current thread (or task from a kernel + * perspective), and PIDFD_SELF_THREAD_GROUP to refer to the current thread + * group leader... + */ +#define PIDFD_SELF_THREAD -10000 /* Current thread. */ +#define PIDFD_SELF_THREAD_GROUP -20000 /* Current thread group leader. */ + +/* + * ...and for userland we make life simpler - PIDFD_SELF refers to the current + * thread, PIDFD_SELF_PROCESS refers to the process thread group leader. + * + * For nearly all practical uses, a user will want to use PIDFD_SELF. + */ +#define PIDFD_SELF PIDFD_SELF_THREAD +#define PIDFD_SELF_PROCESS PIDFD_SELF_THREAD_GROUP + struct pidfd_info { /* * This mask is similar to the request_mask in statx(2). diff --git a/kernel/pid.c b/kernel/pid.c index 924084713be8..22f5d2b2e290 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -564,15 +564,29 @@ struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags) */ struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags) { - unsigned int f_flags; + unsigned int f_flags = 0; struct pid *pid; struct task_struct *task; + enum pid_type type; - pid = pidfd_get_pid(pidfd, &f_flags); - if (IS_ERR(pid)) - return ERR_CAST(pid); + switch (pidfd) { + case PIDFD_SELF_THREAD: + type = PIDTYPE_PID; + pid = get_task_pid(current, type); + break; + case PIDFD_SELF_THREAD_GROUP: + type = PIDTYPE_TGID; + pid = get_task_pid(current, type); + break; + default: + pid = pidfd_get_pid(pidfd, &f_flags); + if (IS_ERR(pid)) + return ERR_CAST(pid); + type = PIDTYPE_TGID; + break; + } - task = get_pid_task(pid, PIDTYPE_TGID); + task = get_pid_task(pid, type); put_pid(pid); if (!task) return ERR_PTR(-ESRCH); diff --git a/kernel/signal.c b/kernel/signal.c index 875e97f6205a..081f19a24506 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -4009,6 +4009,47 @@ static struct pid *pidfd_to_pid(const struct file *file) (PIDFD_SIGNAL_THREAD | PIDFD_SIGNAL_THREAD_GROUP | \ PIDFD_SIGNAL_PROCESS_GROUP) +static int do_pidfd_send_signal(struct pid *pid, int sig, enum pid_type type, + siginfo_t __user *info, unsigned int flags) +{ + kernel_siginfo_t kinfo; + + switch (flags) { + case PIDFD_SIGNAL_THREAD: + type = PIDTYPE_PID; + break; + case PIDFD_SIGNAL_THREAD_GROUP: + type = PIDTYPE_TGID; + break; + case PIDFD_SIGNAL_PROCESS_GROUP: + type = PIDTYPE_PGID; + break; + } + + if (info) { + int ret; + + ret = copy_siginfo_from_user_any(&kinfo, info); + if (unlikely(ret)) + return ret; + + if (unlikely(sig != kinfo.si_signo)) + return -EINVAL; + + /* Only allow sending arbitrary signals to yourself. */ + if ((task_pid(current) != pid || type > PIDTYPE_TGID) && + (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) + return -EPERM; + } else { + prepare_kill_siginfo(sig, &kinfo, type); + } + + if (type == PIDTYPE_PGID) + return kill_pgrp_info(sig, &kinfo, pid); + + return kill_pid_info_type(sig, &kinfo, pid, type); +} + /** * sys_pidfd_send_signal - Signal a process through a pidfd * @pidfd: file descriptor of the process @@ -4026,9 +4067,7 @@ static struct pid *pidfd_to_pid(const struct file *file) SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, siginfo_t __user *, info, unsigned int, flags) { - int ret; struct pid *pid; - kernel_siginfo_t kinfo; enum pid_type type; /* Enforce flags be set to 0 until we add an extension. */ @@ -4039,57 +4078,39 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, if (hweight32(flags & PIDFD_SEND_SIGNAL_FLAGS) > 1) return -EINVAL; - CLASS(fd, f)(pidfd); - if (fd_empty(f)) - return -EBADF; + switch (pidfd) { + case PIDFD_SELF_THREAD: + pid = get_task_pid(current, PIDTYPE_PID); + type = PIDTYPE_PID; + break; + case PIDFD_SELF_THREAD_GROUP: + pid = get_task_pid(current, PIDTYPE_TGID); + type = PIDTYPE_TGID; + break; + default: { + CLASS(fd, f)(pidfd); + if (fd_empty(f)) + return -EBADF; - /* Is this a pidfd? */ - pid = pidfd_to_pid(fd_file(f)); - if (IS_ERR(pid)) - return PTR_ERR(pid); + /* Is this a pidfd? */ + pid = pidfd_to_pid(fd_file(f)); + if (IS_ERR(pid)) + return PTR_ERR(pid); - if (!access_pidfd_pidns(pid)) - return -EINVAL; + if (!access_pidfd_pidns(pid)) + return -EINVAL; - switch (flags) { - case 0: /* Infer scope from the type of pidfd. */ if (fd_file(f)->f_flags & PIDFD_THREAD) type = PIDTYPE_PID; else type = PIDTYPE_TGID; - break; - case PIDFD_SIGNAL_THREAD: - type = PIDTYPE_PID; - break; - case PIDFD_SIGNAL_THREAD_GROUP: - type = PIDTYPE_TGID; - break; - case PIDFD_SIGNAL_PROCESS_GROUP: - type = PIDTYPE_PGID; - break; - } - if (info) { - ret = copy_siginfo_from_user_any(&kinfo, info); - if (unlikely(ret)) - return ret; - - if (unlikely(sig != kinfo.si_signo)) - return -EINVAL; - - /* Only allow sending arbitrary signals to yourself. */ - if ((task_pid(current) != pid || type > PIDTYPE_TGID) && - (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) - return -EPERM; - } else { - prepare_kill_siginfo(sig, &kinfo, type); + return do_pidfd_send_signal(pid, sig, type, info, flags); + } } - if (type == PIDTYPE_PGID) - return kill_pgrp_info(sig, &kinfo, pid); - else - return kill_pid_info_type(sig, &kinfo, pid, type); + return do_pidfd_send_signal(pid, sig, type, info, flags); } static int diff --git a/tools/testing/selftests/mm/guard-pages.c b/tools/testing/selftests/mm/guard-pages.c index ece37212a8a2..525c50d3ec23 100644 --- a/tools/testing/selftests/mm/guard-pages.c +++ b/tools/testing/selftests/mm/guard-pages.c @@ -19,6 +19,8 @@ #include <sys/uio.h> #include <unistd.h> +#include "../pidfd/pidfd.h" + /* * Ignore the checkpatch warning, as per the C99 standard, section 7.14.1.1: * @@ -50,11 +52,6 @@ static void handle_fatal(int c) siglongjmp(signal_jmp_buf, c); } -static int pidfd_open(pid_t pid, unsigned int flags) -{ - return syscall(SYS_pidfd_open, pid, flags); -} - static ssize_t sys_process_madvise(int pidfd, const struct iovec *iovec, size_t n, int advice, unsigned int flags) { @@ -370,14 +367,10 @@ TEST_F(guard_pages, multi_vma) TEST_F(guard_pages, process_madvise) { const unsigned long page_size = self->page_size; - pid_t pid = getpid(); - int pidfd = pidfd_open(pid, 0); char *ptr_region, *ptr1, *ptr2, *ptr3; ssize_t count; struct iovec vec[6]; - ASSERT_NE(pidfd, -1); - /* Reserve region to map over. */ ptr_region = mmap(NULL, 100 * page_size, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0); @@ -425,7 +418,7 @@ TEST_F(guard_pages, process_madvise) ASSERT_EQ(munmap(&ptr_region[99 * page_size], page_size), 0); /* Now guard in one step. */ - count = sys_process_madvise(pidfd, vec, 6, MADV_GUARD_INSTALL, 0); + count = sys_process_madvise(PIDFD_SELF, vec, 6, MADV_GUARD_INSTALL, 0); /* OK we don't have permission to do this, skip. */ if (count == -1 && errno == EPERM) @@ -446,7 +439,7 @@ TEST_F(guard_pages, process_madvise) ASSERT_FALSE(try_read_write_buf(&ptr3[19 * page_size])); /* Now do the same with unguard... */ - count = sys_process_madvise(pidfd, vec, 6, MADV_GUARD_REMOVE, 0); + count = sys_process_madvise(PIDFD_SELF, vec, 6, MADV_GUARD_REMOVE, 0); /* ...and everything should now succeed. */ @@ -463,7 +456,6 @@ TEST_F(guard_pages, process_madvise) ASSERT_EQ(munmap(ptr1, 10 * page_size), 0); ASSERT_EQ(munmap(ptr2, 5 * page_size), 0); ASSERT_EQ(munmap(ptr3, 20 * page_size), 0); - close(pidfd); } /* Assert that unmapping ranges does not leave guard markers behind. */ diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h index 0b96ac4b8ce5..027ebaf14844 100644 --- a/tools/testing/selftests/pidfd/pidfd.h +++ b/tools/testing/selftests/pidfd/pidfd.h @@ -50,6 +50,22 @@ #define PIDFD_NONBLOCK O_NONBLOCK #endif +#ifndef PIDFD_SELF_THREAD +#define PIDFD_SELF_THREAD -10000 /* Current thread. */ +#endif + +#ifndef PIDFD_SELF_THREAD_GROUP +#define PIDFD_SELF_THREAD_GROUP -20000 /* Current thread group leader. */ +#endif + +#ifndef PIDFD_SELF +#define PIDFD_SELF PIDFD_SELF_THREAD +#endif + +#ifndef PIDFD_SELF_PROCESS +#define PIDFD_SELF_PROCESS PIDFD_SELF_THREAD_GROUP +#endif + /* * The kernel reserves 300 pids via RESERVED_PIDS in kernel/pid.c * That means, when it wraps around any pid < 300 will be skipped. diff --git a/tools/testing/selftests/pidfd/pidfd_open_test.c b/tools/testing/selftests/pidfd/pidfd_open_test.c index ce413a221bac..9a40ccb1ff6d 100644 --- a/tools/testing/selftests/pidfd/pidfd_open_test.c +++ b/tools/testing/selftests/pidfd/pidfd_open_test.c @@ -31,7 +31,7 @@ #define PIDFD_INFO_CGROUPID (1UL << 0) struct pidfd_info { - __u64 request_mask; + __u64 mask; __u64 cgroupid; __u32 pid; __u32 tgid; @@ -148,7 +148,7 @@ out: int main(int argc, char **argv) { struct pidfd_info info = { - .request_mask = PIDFD_INFO_CGROUPID, + .mask = PIDFD_INFO_CGROUPID, }; int pidfd = -1, ret = 1; pid_t pid; @@ -227,7 +227,7 @@ int main(int argc, char **argv) getegid(), info.sgid); goto on_error; } - if ((info.request_mask & PIDFD_INFO_CGROUPID) && info.cgroupid == 0) { + if ((info.mask & PIDFD_INFO_CGROUPID) && info.cgroupid == 0) { ksft_print_msg("cgroupid should not be 0 when PIDFD_INFO_CGROUPID is set\n"); goto on_error; } diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c index e9728e86b4f2..fcd85cad9f18 100644 --- a/tools/testing/selftests/pidfd/pidfd_test.c +++ b/tools/testing/selftests/pidfd/pidfd_test.c @@ -42,12 +42,41 @@ static pid_t pidfd_clone(int flags, int *pidfd, int (*fn)(void *)) #endif } -static int signal_received; +static pthread_t signal_received; static void set_signal_received_on_sigusr1(int sig) { if (sig == SIGUSR1) - signal_received = 1; + signal_received = pthread_self(); +} + +static int send_signal(int pidfd) +{ + int ret = 0; + + if (sys_pidfd_send_signal(pidfd, SIGUSR1, NULL, 0) < 0) { + ret = -EINVAL; + goto exit; + } + + if (signal_received != pthread_self()) { + ret = -EINVAL; + goto exit; + } + +exit: + signal_received = 0; + return ret; +} + +static void *send_signal_worker(void *arg) +{ + int pidfd = (int)(intptr_t)arg; + int ret; + + /* We forward any errors for the caller to handle. */ + ret = send_signal(pidfd); + return (void *)(intptr_t)ret; } /* @@ -56,8 +85,11 @@ static void set_signal_received_on_sigusr1(int sig) */ static int test_pidfd_send_signal_simple_success(void) { - int pidfd, ret; + int pidfd; const char *test_name = "pidfd_send_signal send SIGUSR1"; + pthread_t thread; + void *thread_res; + int err; if (!have_pidfd_send_signal) { ksft_test_result_skip( @@ -66,25 +98,45 @@ static int test_pidfd_send_signal_simple_success(void) return 0; } + signal(SIGUSR1, set_signal_received_on_sigusr1); + + /* Try sending a signal to ourselves via /proc/self. */ pidfd = open("/proc/self", O_DIRECTORY | O_CLOEXEC); if (pidfd < 0) ksft_exit_fail_msg( "%s test: Failed to open process file descriptor\n", test_name); + err = send_signal(pidfd); + if (err) + ksft_exit_fail_msg( + "%s test: Error %d on sending pidfd signal\n", + test_name, err); + close(pidfd); - signal(SIGUSR1, set_signal_received_on_sigusr1); + /* Now try the same thing only using PIDFD_SELF_THREAD_GROUP. */ + err = send_signal(PIDFD_SELF_THREAD_GROUP); + if (err) + ksft_exit_fail_msg( + "%s test: Error %d on PIDFD_SELF_THREAD_GROUP signal\n", + test_name, err); - ret = sys_pidfd_send_signal(pidfd, SIGUSR1, NULL, 0); - close(pidfd); - if (ret < 0) - ksft_exit_fail_msg("%s test: Failed to send signal\n", + /* + * Now try the same thing in a thread and assert thread ID is equal to + * worker thread ID. + */ + if (pthread_create(&thread, NULL, send_signal_worker, + (void *)(intptr_t)PIDFD_SELF_THREAD)) + ksft_exit_fail_msg("%s test: Failed to create thread\n", test_name); - - if (signal_received != 1) - ksft_exit_fail_msg("%s test: Failed to receive signal\n", + if (pthread_join(thread, &thread_res)) + ksft_exit_fail_msg("%s test: Failed to join thread\n", test_name); + err = (int)(intptr_t)thread_res; + if (err) + ksft_exit_fail_msg( + "%s test: Error %d on PIDFD_SELF_THREAD signal\n", + test_name, err); - signal_received = 0; ksft_test_result_pass("%s test: Sent signal\n", test_name); return 0; } |