Fix kmod build on Linux 5.8 (#1672)

* Fix kmod build on Linux 5.8 * Moved kernel hacks into their own file. * probe-builder: Use CONFIG_GCC_VERSION if available Kernel 5.8 changed the format of the compiler version string so rather than chasing it, use CONFIG_GCC_VERSION if we have it (5.8.0 does support it, so we use it there, for older versions we fall back to parsing LINUX_COMPILER) Co-authored-by: Grzegorz Nosek <[email protected]>
draios · Aug 4, 2020 · 2691cbc · 2691cbc
1 parent 3193643
commit 2691cbc
Show file tree

Hide file tree

Showing 4 changed files with 110 additions and 81 deletions.
diff --git a/driver/CMakeLists.txt b/driver/CMakeLists.txt
@@ -45,6 +45,7 @@ set(DRIVER_SOURCES
 	event_table.c
 	fillers_table.c
 	flags_table.c
+	kernel_hacks.h
 	main.c
 	ppm.h
 	ppm_events.c

diff --git a/driver/kernel_hacks.h b/driver/kernel_hacks.h
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2020 Draios Inc. dba Sysdig.
+ *
+ * This file is dual licensed under either the MIT or GPL 2. See MIT.txt
+ * or GPL2.txt for full copies of the license.
+ */
+
+/**
+ * @file kernel_hacks.h
+ *
+ * This file contains kernel-version-dependent preprocessor instructions to
+ * help the driver compile on as many kernel versions as possible.
+ */
+
+#include <linux/version.h>
+
+/* probe_kernel_read() only added in kernel 2.6.26, name changed in 5.8.0 */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 26)
+static inline long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
+{
+	long ret;
+	mm_segment_t old_fs = get_fs();
+
+	set_fs(KERNEL_DS);
+	pagefault_disable();
+	ret = __copy_from_user_inatomic(dst, (__force const void __user *)src, size);
+	pagefault_enable();
+	set_fs(old_fs);
+
+	return ret ? -EFAULT : 0;
+}
+#elif LINUX_VERSION_CODE < KERNEL_VERSION(5, 8, 0)
+#define copy_from_kernel_nofault probe_kernel_read
+#endif
+
+
+/*
+ * Linux 5.6 kernels no longer include the old 32-bit timeval
+ * structures. But the syscalls (might) still use them.
+ */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
+#include <linux/time64.h>
+struct compat_timespec {
+	int32_t tv_sec;
+	int32_t tv_nsec;
+};
+
+struct timespec {
+	int32_t tv_sec;
+	int32_t tv_nsec;
+};
+
+struct timeval {
+	int32_t tv_sec;
+	int32_t tv_usec;
+};
+#else
+#define timeval64 timeval
+#endif
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 9, 0)
+static inline struct inode *file_inode(struct file *f)
+{
+	return f->f_path.dentry->d_inode;
+}
+#endif
+
+/*
+ * Linux 5.1 kernels modify the syscall_get_arguments function to always
+ * return all arguments rather than allowing the caller to select which
+ * arguments are desired. This wrapper replicates the original
+ * functionality.
+ */
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(5, 1, 0))
+#define syscall_get_arguments_deprecated syscall_get_arguments
+#else
+#define syscall_get_arguments_deprecated(_task, _reg, _start, _len, _args) \
+	do { \
+	    unsigned long _sga_args[6] = {}; \
+	    syscall_get_arguments(_task, _reg, _sga_args); \
+	    memcpy(_args, &_sga_args[_start], _len * sizeof(unsigned long)); \
+	} while(0)
+#endif
diff --git a/driver/ppm_fillers.c b/driver/ppm_fillers.c
@@ -84,59 +84,11 @@ or GPL2.txt for full copies of the license.
 #include <linux/bpf.h>
 #endif
 
-/*
- * Linux 5.6 kernels no longer include the old 32-bit timeval
- * structures. But the syscalls (might) still use them.
- */
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
-#include <linux/time64.h>
-struct compat_timespec {
-	int32_t tv_sec;
-	int32_t tv_nsec;
-};
-
-struct timespec {
-	int32_t tv_sec;
-	int32_t tv_nsec;
-};
-
-struct timeval {
-	int32_t tv_sec;
-	int32_t tv_usec;
-};
-#else
-#define timeval64 timeval
-#endif
-
-#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 9, 0)
-static inline struct inode *file_inode(struct file *f)
-{
-	return f->f_path.dentry->d_inode;
-}
-#endif
+#include "kernel_hacks.h"
 #endif /* UDIG */
 
 #define merge_64(hi, lo) ((((unsigned long long)(hi)) << 32) + ((lo) & 0xffffffffUL))
 
-/*
- * Linux 5.1 kernels modify the syscall_get_arguments function to always
- * return all arguments rather than allowing the caller to select which
- * arguments are desired. This wrapper replicates the original
- * functionality.
- */
-#ifndef UDIG
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(5, 1, 0))
-#define syscall_get_arguments_deprecated syscall_get_arguments
-#else
-#define syscall_get_arguments_deprecated(_task, _reg, _start, _len, _args) \
-	do { \
-		unsigned long _sga_args[6] = {}; \
-		syscall_get_arguments(_task, _reg, _sga_args); \
-		memcpy(_args, &_sga_args[_start], _len * sizeof(unsigned long)); \
-	} while(0)
-#endif
-#endif /* UDIG */
-
 #ifndef UDIG
 static inline struct pid_namespace *pid_ns_for_children(struct task_struct *task)
 {
@@ -701,23 +653,6 @@ static int compat_accumulate_argv_or_env(compat_uptr_t argv,
 
 #endif
 
-// probe_kernel_read() only added in kernel 2.6.26
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 26)
-long probe_kernel_read(void *dst, const void *src, size_t size)
-{
-	long ret;
-	mm_segment_t old_fs = get_fs();
-
-	set_fs(KERNEL_DS);
-	pagefault_disable();
-	ret = __copy_from_user_inatomic(dst, (__force const void __user *)src, size);
-	pagefault_enable();
-	set_fs(old_fs);
-
-	return ret ? -EFAULT : 0;
-}
-#endif
-
 static int ppm_get_tty(void)
 {
 	/* Locking of the signal structures seems too complicated across
@@ -738,25 +673,25 @@ static int ppm_get_tty(void)
 	if (!sig)
 		return 0;
 
-	if (unlikely(probe_kernel_read(&tty, &sig->tty, sizeof(tty))))
+	if (unlikely(copy_from_kernel_nofault(&tty, &sig->tty, sizeof(tty))))
 		return 0;
 
 	if (!tty)
 		return 0;
 
-	if (unlikely(probe_kernel_read(&index, &tty->index, sizeof(index))))
+	if (unlikely(copy_from_kernel_nofault(&index, &tty->index, sizeof(index))))
 		return 0;
 
-	if (unlikely(probe_kernel_read(&driver, &tty->driver, sizeof(driver))))
+	if (unlikely(copy_from_kernel_nofault(&driver, &tty->driver, sizeof(driver))))
 		return 0;
 
 	if (!driver)
 		return 0;
 
-	if (unlikely(probe_kernel_read(&major, &driver->major, sizeof(major))))
+	if (unlikely(copy_from_kernel_nofault(&major, &driver->major, sizeof(major))))
 		return 0;
 
-	if (unlikely(probe_kernel_read(&minor_start, &driver->minor_start, sizeof(minor_start))))
+	if (unlikely(copy_from_kernel_nofault(&minor_start, &driver->minor_start, sizeof(minor_start))))
 		return 0;
 
 	tty_nr = new_encode_dev(MKDEV(major, minor_start) + index);

diff --git a/probe-builder/build-probe-binaries b/probe-builder/build-probe-binaries
@@ -296,18 +296,28 @@ function build_probe {
 	elif [ -n "${BUILDER_DISTRO:-}" ]
 	then
 		# Try to find the gcc version used to build this particular kernel
-		# There is CONFIG_GCC_VERSION=90201 in the kernel config but it's
-		# too new for us to depend on
-		if [ -e $KERNELDIR/include/generated/compile.h ]
+		# Check CONFIG_GCC_VERSION=90201 in the kernel config first
+		# as 5.8.0 seems to have a different format for the LINUX_COMPILER string
+		if [ -e $KERNELDIR/include/generated/autoconf.h ]
 		then
-			BUILDER_GCC_VERSION=$(grep -Po '(?<=^#define LINUX_COMPILER "gcc version )[0-9.]+' $KERNELDIR/include/generated/compile.h)
-		elif [ -e $KERNELDIR/include/linux/compile.h ]
-		then
-			# RHEL6
-			BUILDER_GCC_VERSION=$(grep -Po '(?<=^#define LINUX_COMPILER "gcc version )[0-9.]+' $KERNELDIR/include/linux/compile.h)
+			BUILDER_GCC_VERSION=$(grep -Po '(?<=^#define CONFIG_GCC_VERSION ).*' $KERNELDIR/include/generated/autoconf.h | sed '-res@(.*)(..)(..)$@\1\.\2\.\3@' '-es@\.0@\.@g')
 		else
-			# ancient Ubuntu gets and ancient compiler
-			BUILDER_GCC_VERSION=4.8.0
+			BUILDER_GCC_VERSION=
+		fi
+
+		if [ -z "$BUILDER_GCC_VERSION" ]
+		then
+			if [ -e $KERNELDIR/include/generated/compile.h ]
+			then
+				BUILDER_GCC_VERSION=$(grep -Po '(?<=^#define LINUX_COMPILER "gcc version )[0-9.]+' $KERNELDIR/include/generated/compile.h)
+			elif [ -e $KERNELDIR/include/linux/compile.h ]
+			then
+				# RHEL6
+				BUILDER_GCC_VERSION=$(grep -Po '(?<=^#define LINUX_COMPILER "gcc version )[0-9.]+' $KERNELDIR/include/linux/compile.h)
+			else
+				# ancient Ubuntu gets and ancient compiler
+				BUILDER_GCC_VERSION=4.8.0
+			fi
 		fi
 
 		# We don't really care about the compiler patch levels, only the major/minor version