1 files changed, 417 insertions, 19 deletions

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 0f932b22f9ec..528ac90eda5d 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <trace/syscall.h>
 #include <trace/events/syscalls.h>
+#include <linux/kernel_stat.h>
 #include <linux/syscalls.h>
 #include <linux/slab.h>
 #include <linux/kernel.h>
@@ -123,6 +124,9 @@ const char *get_syscall_name(int syscall)
 	return entry->name;
 }
 
+/* Added to user strings when max limit is reached */
+#define EXTRA "..."
+
 static enum print_line_t
 print_syscall_enter(struct trace_iterator *iter, int flags,
 		    struct trace_event *event)
@@ -132,7 +136,9 @@ print_syscall_enter(struct trace_iterator *iter, int flags,
 	struct trace_entry *ent = iter->ent;
 	struct syscall_trace_enter *trace;
 	struct syscall_metadata *entry;
-	int i, syscall;
+	int i, syscall, val;
+	unsigned char *ptr;
+	int len;
 
 	trace = (typeof(trace))ent;
 	syscall = trace->nr;
@@ -167,6 +173,19 @@ print_syscall_enter(struct trace_iterator *iter, int flags,
 		else
 			trace_seq_printf(s, "%s: 0x%lx", entry->args[i],
 					 trace->args[i]);
+
+		if (!(BIT(i) & entry->user_mask))
+			continue;
+
+		/* This arg points to a user space string */
+		ptr = (void *)trace->args + sizeof(long) * entry->nb_args;
+		val = *(int *)ptr;
+
+		/* The value is a dynamic string (len << 16 | offset) */
+		ptr = (void *)ent + (val & 0xffff);
+		len = val >> 16;
+
+		trace_seq_printf(s, " \"%.*s\"", len, ptr);
 	}
 
 	trace_seq_putc(s, ')');
@@ -223,15 +242,27 @@ __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
 
 	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 	for (i = 0; i < entry->nb_args; i++) {
-		pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
-				entry->args[i], sizeof(unsigned long),
-				i == entry->nb_args - 1 ? "" : ", ");
+		if (i)
+			pos += snprintf(buf + pos, LEN_OR_ZERO, ", ");
+		pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx",
+				entry->args[i], sizeof(unsigned long));
+
+		if (!(BIT(i) & entry->user_mask))
+			continue;
+
+		/* Add the format for the user space string */
+		pos += snprintf(buf + pos, LEN_OR_ZERO, " \\\"%%s\\\"");
 	}
 	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 
 	for (i = 0; i < entry->nb_args; i++) {
 		pos += snprintf(buf + pos, LEN_OR_ZERO,
 				", ((unsigned long)(REC->%s))", entry->args[i]);
+		if (!(BIT(i) & entry->user_mask))
+			continue;
+		/* The user space string for arg has name __<arg>_val */
+		pos += snprintf(buf + pos, LEN_OR_ZERO, ", __get_str(__%s_val)",
+				entry->args[i]);
 	}
 
 #undef LEN_OR_ZERO
@@ -277,8 +308,12 @@ static int __init syscall_enter_define_fields(struct trace_event_call *call)
 {
 	struct syscall_trace_enter trace;
 	struct syscall_metadata *meta = call->data;
+	unsigned long mask;
+	char *arg;
 	int offset = offsetof(typeof(trace), args);
+	int idx;
 	int ret = 0;
+	int len;
 	int i;
 
 	for (i = 0; i < meta->nb_args; i++) {
@@ -291,9 +326,148 @@ static int __init syscall_enter_define_fields(struct trace_event_call *call)
 		offset += sizeof(unsigned long);
 	}
 
+	if (ret || !meta->user_mask)
+		return ret;
+
+	mask = meta->user_mask;
+	idx = ffs(mask) - 1;
+
+	/*
+	 * User space strings are faulted into a temporary buffer and then
+	 * added as a dynamic string to the end of the event.
+	 * The user space string name for the arg pointer is "__<arg>_val".
+	 */
+	len = strlen(meta->args[idx]) + sizeof("___val");
+	arg = kmalloc(len, GFP_KERNEL);
+	if (WARN_ON_ONCE(!arg)) {
+		meta->user_mask = 0;
+		return -ENOMEM;
+	}
+
+	snprintf(arg, len, "__%s_val", meta->args[idx]);
+
+	ret = trace_define_field(call, "__data_loc char[]",
+				 arg, offset, sizeof(int), 0,
+				 FILTER_OTHER);
+	if (ret)
+		kfree(arg);
 	return ret;
 }
 
+#define SYSCALL_FAULT_BUF_SZ 512
+
+/* Use the tracing per CPU buffer infrastructure to copy from user space */
+struct syscall_user_buffer {
+	struct trace_user_buf_info	buf;
+	struct rcu_head			rcu;
+};
+
+static struct syscall_user_buffer *syscall_buffer;
+
+static int syscall_fault_buffer_enable(void)
+{
+	struct syscall_user_buffer *sbuf;
+	int ret;
+
+	lockdep_assert_held(&syscall_trace_lock);
+
+	if (syscall_buffer) {
+		trace_user_fault_get(&syscall_buffer->buf);
+		return 0;
+	}
+
+	sbuf = kmalloc(sizeof(*sbuf), GFP_KERNEL);
+	if (!sbuf)
+		return -ENOMEM;
+
+	ret = trace_user_fault_init(&sbuf->buf, SYSCALL_FAULT_BUF_SZ);
+	if (ret < 0) {
+		kfree(sbuf);
+		return ret;
+	}
+
+	WRITE_ONCE(syscall_buffer, sbuf);
+
+	return 0;
+}
+
+static void rcu_free_syscall_buffer(struct rcu_head *rcu)
+{
+	struct syscall_user_buffer *sbuf =
+		container_of(rcu, struct syscall_user_buffer, rcu);
+
+	trace_user_fault_destroy(&sbuf->buf);
+	kfree(sbuf);
+}
+
+
+static void syscall_fault_buffer_disable(void)
+{
+	struct syscall_user_buffer *sbuf = syscall_buffer;
+
+	lockdep_assert_held(&syscall_trace_lock);
+
+	if (trace_user_fault_put(&sbuf->buf))
+		return;
+
+	WRITE_ONCE(syscall_buffer, NULL);
+	call_rcu_tasks_trace(&sbuf->rcu, rcu_free_syscall_buffer);
+}
+
+static int syscall_copy_user(char *buf, const char __user *ptr,
+			     size_t size, void *data)
+{
+	unsigned long *ret_size = data;
+	int ret;
+
+	ret = strncpy_from_user(buf, ptr, size);
+	if (ret < 0)
+		return 1;
+	*ret_size = ret;
+	return 0;
+}
+
+static char *sys_fault_user(struct syscall_metadata *sys_data,
+			    struct syscall_user_buffer *sbuf,
+			    unsigned long *args, unsigned int *data_size)
+{
+	unsigned long size = SYSCALL_FAULT_BUF_SZ - 1;
+	unsigned long mask = sys_data->user_mask;
+	int idx = ffs(mask) - 1;
+	char *ptr;
+	char *buf;
+
+	/* Get the pointer to user space memory to read */
+	ptr = (char *)args[idx];
+	*data_size = 0;
+
+	buf = trace_user_fault_read(&sbuf->buf, ptr, size,
+				    syscall_copy_user, &size);
+	if (!buf)
+		return NULL;
+
+	/* Replace any non-printable characters with '.' */
+	for (int i = 0; i < size; i++) {
+		if (!isprint(buf[i]))
+			buf[i] = '.';
+	}
+
+	/*
+	 * If the text was truncated due to our max limit, add "..." to
+	 * the string.
+	 */
+	if (size > SYSCALL_FAULT_BUF_SZ - sizeof(EXTRA)) {
+		strscpy(buf + SYSCALL_FAULT_BUF_SZ - sizeof(EXTRA),
+			EXTRA, sizeof(EXTRA));
+		size = SYSCALL_FAULT_BUF_SZ;
+	} else {
+		buf[size++] = '\0';
+	}
+
+	*data_size = size;
+	return buf;
+}
+
 static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 {
 	struct trace_array *tr = data;
@@ -302,15 +476,17 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 	struct syscall_metadata *sys_data;
 	struct trace_event_buffer fbuffer;
 	unsigned long args[6];
+	char *user_ptr;
+	int user_size = 0;
 	int syscall_nr;
-	int size;
+	int size = 0;
+	bool mayfault;
 
 	/*
 	 * Syscall probe called with preemption enabled, but the ring
 	 * buffer and per-cpu data require preemption to be disabled.
 	 */
 	might_fault();
-	guard(preempt_notrace)();
 
 	syscall_nr = trace_get_syscall_nr(current, regs);
 	if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
@@ -327,7 +503,32 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 	if (!sys_data)
 		return;
 
-	size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
+	/* Check if this syscall event faults in user space memory */
+	mayfault = sys_data->user_mask != 0;
+
+	guard(preempt_notrace)();
+
+	syscall_get_arguments(current, regs, args);
+
+	if (mayfault) {
+		struct syscall_user_buffer *sbuf;
+
+		/* If the syscall_buffer is NULL, tracing is being shutdown */
+		sbuf = READ_ONCE(syscall_buffer);
+		if (!sbuf)
+			return;
+
+		user_ptr = sys_fault_user(sys_data, sbuf, args, &user_size);
+		/*
+		 * user_size is the amount of data to append.
+		 * Need to add 4 for the meta field that points to
+		 * the user memory at the end of the event and also
+		 * stores its size.
+		 */
+		size = 4 + user_size;
+	}
+
+	size += sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 
 	entry = trace_event_buffer_reserve(&fbuffer, trace_file, size);
 	if (!entry)
@@ -335,9 +536,36 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 
 	entry = ring_buffer_event_data(fbuffer.event);
 	entry->nr = syscall_nr;
-	syscall_get_arguments(current, regs, args);
+
 	memcpy(entry->args, args, sizeof(unsigned long) * sys_data->nb_args);
 
+	if (mayfault) {
+		void *ptr;
+		int val;
+
+		/*
+		 * Set the pointer to point to the meta data of the event
+		 * that has information about the stored user space memory.
+		 */
+		ptr = (void *)entry->args + sizeof(unsigned long) * sys_data->nb_args;
+
+		/*
+		 * The meta data will store the offset of the user data from
+		 * the beginning of the event.
+		 */
+		val  = (ptr - (void *)entry) + 4;
+
+		/* Store the offset and the size into the meta data */
+		*(int *)ptr = val | (user_size << 16);
+
+		/* Nothing to do if the user space was empty or faulted */
+		if (user_size) {
+			/* Now store the user space data into the event */
+			ptr += 4;
+			memcpy(ptr, user_ptr, user_size);
+		}
+	}
+
 	trace_event_buffer_commit(&fbuffer);
 }
 
@@ -386,39 +614,50 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
 static int reg_event_syscall_enter(struct trace_event_file *file,
 				   struct trace_event_call *call)
 {
+	struct syscall_metadata *sys_data = call->data;
 	struct trace_array *tr = file->tr;
 	int ret = 0;
 	int num;
 
-	num = ((struct syscall_metadata *)call->data)->syscall_nr;
+	num = sys_data->syscall_nr;
 	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return -ENOSYS;
-	mutex_lock(&syscall_trace_lock);
-	if (!tr->sys_refcount_enter)
+	guard(mutex)(&syscall_trace_lock);
+	if (sys_data->user_mask) {
+		ret = syscall_fault_buffer_enable();
+		if (ret < 0)
+			return ret;
+	}
+	if (!tr->sys_refcount_enter) {
 		ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
-	if (!ret) {
-		WRITE_ONCE(tr->enter_syscall_files[num], file);
-		tr->sys_refcount_enter++;
+		if (ret < 0) {
+			if (sys_data->user_mask)
+				syscall_fault_buffer_disable();
+			return ret;
+		}
 	}
-	mutex_unlock(&syscall_trace_lock);
-	return ret;
+	WRITE_ONCE(tr->enter_syscall_files[num], file);
+	tr->sys_refcount_enter++;
+	return 0;
 }
 
 static void unreg_event_syscall_enter(struct trace_event_file *file,
 				      struct trace_event_call *call)
 {
+	struct syscall_metadata *sys_data = call->data;
 	struct trace_array *tr = file->tr;
 	int num;
 
-	num = ((struct syscall_metadata *)call->data)->syscall_nr;
+	num = sys_data->syscall_nr;
 	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return;
-	mutex_lock(&syscall_trace_lock);
+	guard(mutex)(&syscall_trace_lock);
 	tr->sys_refcount_enter--;
 	WRITE_ONCE(tr->enter_syscall_files[num], NULL);
 	if (!tr->sys_refcount_enter)
 		unregister_trace_sys_enter(ftrace_syscall_enter, tr);
-	mutex_unlock(&syscall_trace_lock);
+	if (sys_data->user_mask)
+		syscall_fault_buffer_disable();
 }
 
 static int reg_event_syscall_exit(struct trace_event_file *file,
@@ -459,6 +698,163 @@ static void unreg_event_syscall_exit(struct trace_event_file *file,
 	mutex_unlock(&syscall_trace_lock);
 }
 
+/*
+ * For system calls that reference user space memory that can
+ * be recorded into the event, set the system call meta data's user_mask
+ * to the "args" index that points to the user space memory to retrieve.
+ */
+static void check_faultable_syscall(struct trace_event_call *call, int nr)
+{
+	struct syscall_metadata *sys_data = call->data;
+
+	/* Only work on entry */
+	if (sys_data->enter_event != call)
+		return;
+
+	switch (nr) {
+	/* user arg at position 0 */
+#ifdef __NR_access
+	case __NR_access:
+#endif
+	case __NR_acct:
+	case __NR_add_key: /* Just _type. TODO add _description */
+	case __NR_chdir:
+#ifdef  __NR_chown
+	case __NR_chown:
+#endif
+#ifdef  __NR_chmod
+	case __NR_chmod:
+#endif
+	case __NR_chroot:
+#ifdef __NR_creat
+	case __NR_creat:
+#endif
+	case __NR_delete_module:
+	case __NR_execve:
+	case __NR_fsopen:
+	case __NR_getxattr: /* Just pathname, TODO add name */
+#ifdef __NR_lchown
+	case __NR_lchown:
+#endif
+	case __NR_lgetxattr: /* Just pathname, TODO add name */
+	case __NR_lremovexattr: /* Just pathname, TODO add name */
+#ifdef __NR_link
+	case __NR_link: /* Just oldname. TODO add newname */
+#endif
+	case __NR_listxattr: /* Just pathname, TODO add list */
+	case __NR_llistxattr: /* Just pathname, TODO add list */
+	case __NR_lsetxattr: /* Just pathname, TODO add list */
+#ifdef __NR_open
+	case __NR_open:
+#endif
+	case __NR_memfd_create:
+	case __NR_mount: /* Just dev_name, TODO add dir_name and type */
+#ifdef __NR_mkdir
+	case __NR_mkdir:
+#endif
+#ifdef __NR_mknod
+	case __NR_mknod:
+#endif
+	case __NR_mq_open:
+	case __NR_mq_unlink:
+	case __NR_pivot_root: /* Just new_root, TODO add old_root */
+#ifdef __NR_readlink
+	case __NR_readlink:
+#endif
+	case __NR_removexattr: /* Just pathname, TODO add name */
+#ifdef __NR_rename
+	case __NR_rename: /* Just oldname. TODO add newname */
+#endif
+	case __NR_request_key: /* Just _type. TODO add _description */
+#ifdef  __NR_rmdir
+	case __NR_rmdir:
+#endif
+	case __NR_setxattr: /* Just pathname, TODO add list */
+	case __NR_shmdt:
+#ifdef __NR_statfs
+	case __NR_statfs:
+#endif
+	case __NR_swapon:
+	case __NR_swapoff:
+#ifdef __NR_symlink
+	case __NR_symlink: /* Just oldname. TODO add newname */
+#endif
+#ifdef __NR_truncate
+	case __NR_truncate:
+#endif
+#ifdef __NR_unlink
+	case __NR_unlink:
+#endif
+	case __NR_umount2:
+#ifdef __NR_utime
+	case __NR_utime:
+#endif
+#ifdef __NR_utimes
+	case __NR_utimes:
+#endif
+		sys_data->user_mask = BIT(0);
+		break;
+	/* user arg at position 1 */
+	case __NR_execveat:
+	case __NR_faccessat:
+	case __NR_faccessat2:
+	case __NR_finit_module:
+	case __NR_fchmodat:
+	case __NR_fchmodat2:
+	case __NR_fchownat:
+	case __NR_fgetxattr:
+	case __NR_flistxattr:
+	case __NR_fsetxattr:
+	case __NR_fspick:
+	case __NR_fremovexattr:
+#ifdef __NR_futimesat
+	case __NR_futimesat:
+#endif
+	case __NR_getxattrat: /* Just pathname, TODO add name */
+	case __NR_inotify_add_watch:
+	case __NR_linkat: /* Just oldname. TODO add newname */
+	case __NR_listxattrat: /* Just pathname, TODO add list */
+	case __NR_mkdirat:
+	case __NR_mknodat:
+	case __NR_mount_setattr:
+	case __NR_move_mount: /* Just from_pathname, TODO add to_pathname */
+	case __NR_name_to_handle_at:
+#ifdef __NR_newfstatat
+	case __NR_newfstatat:
+#endif
+	case __NR_openat:
+	case __NR_openat2:
+	case __NR_open_tree:
+	case __NR_open_tree_attr:
+	case __NR_readlinkat:
+#ifdef __NR_renameat
+	case __NR_renameat: /* Just oldname. TODO add newname */
+#endif
+	case __NR_renameat2: /* Just oldname. TODO add newname */
+	case __NR_removexattrat: /* Just pathname, TODO add name */
+	case __NR_quotactl:
+	case __NR_setxattrat: /* Just pathname, TODO add list */
+	case __NR_syslog:
+	case __NR_symlinkat: /* Just oldname. TODO add newname */
+	case __NR_statx:
+	case __NR_unlinkat:
+	case __NR_utimensat:
+		sys_data->user_mask = BIT(1);
+		break;
+	/* user arg at position 2 */
+	case __NR_init_module:
+	case __NR_fsconfig:
+		sys_data->user_mask = BIT(2);
+		break;
+	/* user arg at position 4 */
+	case __NR_fanotify_mark:
+		sys_data->user_mask = BIT(4);
+		break;
+	default:
+		sys_data->user_mask = 0;
+	}
+}
+
 static int __init init_syscall_trace(struct trace_event_call *call)
 {
 	int id;
@@ -471,6 +867,8 @@ static int __init init_syscall_trace(struct trace_event_call *call)
 		return -ENOSYS;
 	}
 
+	check_faultable_syscall(call, num);
+
 	if (set_syscall_print_fmt(call) < 0)
 		return -ENOMEM;