From: Josh Poimboeuf <jpoimboe@kernel.org>
Add a debug feature to validate all .sframe sections when first loading
the file rather than on demand.
[ Jens Remus: Add support for PC-relative FDE function start address.
Adjust to rename of struct sframe_fre to sframe_fre_internal. ]
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Indu Bhagat <indu.bhagat@oracle.com>
Cc: "Jose E. Marchesi" <jemarch@gnu.org>
Cc: Beau Belgrave <beaub@linux.microsoft.com>
Cc: Jens Remus <jremus@linux.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Sam James <sam@gentoo.org>
Cc: Kees Cook <kees@kernel.org>
Cc: "Carlos O'Donell" <codonell@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
---
Notes (jremus):
Changes in v12:
- Adjust to use internal SFrame FDE representation.
- Adjust to rename of struct sframe_fre to sframe_fre_internal.
Changes in v11:
- Support for SFrame V2 PC-relative FDE function start address.
arch/Kconfig | 19 +++++++++
kernel/unwind/sframe.c | 97 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 116 insertions(+)
diff --git a/arch/Kconfig b/arch/Kconfig
index ab1941ef1411..06c4f909398c 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -493,6 +493,25 @@ config HAVE_UNWIND_USER_SFRAME
bool
select UNWIND_USER
+config SFRAME_VALIDATION
+ bool "Enable .sframe section debugging"
+ depends on HAVE_UNWIND_USER_SFRAME
+ depends on DYNAMIC_DEBUG
+ help
+ When adding an .sframe section for a task, validate the entire
+ section immediately rather than on demand.
+
+ This is a debug feature which is helpful for rooting out .sframe
+ section issues. If the .sframe section is corrupt, it will fail to
+ load immediately, with more information provided in dynamic printks.
+
+ This has a significant page cache footprint due to its reading of the
+ entire .sframe section for every loaded executable and shared
+ library. Also, it's done for all processes, even those which don't
+ get stack traced by the kernel. Not recommended for general use.
+
+ If unsure, say N.
+
config HAVE_PERF_REGS
bool
help
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 7d3e286c1b23..6465e7a315bc 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -351,6 +351,99 @@ int sframe_find(unsigned long ip, struct unwind_user_frame *frame)
return ret;
}
+#ifdef CONFIG_SFRAME_VALIDATION
+
+static int safe_read_fde(struct sframe_section *sec,
+ unsigned int fde_num, struct sframe_fde_internal *fde)
+{
+ int ret;
+
+ if (!user_read_access_begin((void __user *)sec->sframe_start,
+ sec->sframe_end - sec->sframe_start))
+ return -EFAULT;
+ ret = __read_fde(sec, fde_num, fde);
+ user_read_access_end();
+ return ret;
+}
+
+static int safe_read_fre(struct sframe_section *sec,
+ struct sframe_fde_internal *fde,
+ unsigned long fre_addr,
+ struct sframe_fre_internal *fre)
+{
+ int ret;
+
+ if (!user_read_access_begin((void __user *)sec->sframe_start,
+ sec->sframe_end - sec->sframe_start))
+ return -EFAULT;
+ ret = __read_fre(sec, fde, fre_addr, fre);
+ user_read_access_end();
+ return ret;
+}
+
+static int sframe_validate_section(struct sframe_section *sec)
+{
+ unsigned long prev_ip = 0;
+ unsigned int i;
+
+ for (i = 0; i < sec->num_fdes; i++) {
+ struct sframe_fre_internal *fre, *prev_fre = NULL;
+ unsigned long ip, fre_addr;
+ struct sframe_fde_internal fde;
+ struct sframe_fre_internal fres[2];
+ bool which = false;
+ unsigned int j;
+ int ret;
+
+ ret = safe_read_fde(sec, i, &fde);
+ if (ret)
+ return ret;
+
+ ip = fde.func_start_addr;
+ if (ip <= prev_ip) {
+ dbg_sec("fde %u not sorted\n", i);
+ return -EFAULT;
+ }
+ prev_ip = ip;
+
+ fre_addr = sec->fres_start + fde.fres_off;
+ for (j = 0; j < fde.fres_num; j++) {
+ int ret;
+
+ fre = which ? fres : fres + 1;
+ which = !which;
+
+ ret = safe_read_fre(sec, &fde, fre_addr, fre);
+ if (ret) {
+ dbg_sec("fde %u: __read_fre(%u) failed\n", i, j);
+ dbg_sec("FDE: func_start_addr:0x%lx func_size:0x%x fres_off:0x%x fres_num:%d info:%u rep_size:%u\n",
+ fde.func_start_addr, fde.func_size,
+ fde.fres_off, fde.fres_num,
+ fde.info, fde.rep_size);
+ return ret;
+ }
+
+ fre_addr += fre->size;
+
+ if (prev_fre && fre->ip_off <= prev_fre->ip_off) {
+ dbg_sec("fde %u: fre %u not sorted\n", i, j);
+ return -EFAULT;
+ }
+
+ prev_fre = fre;
+ }
+ }
+
+ return 0;
+}
+
+#else /* !CONFIG_SFRAME_VALIDATION */
+
+static int sframe_validate_section(struct sframe_section *sec) { return 0; }
+
+#endif /* !CONFIG_SFRAME_VALIDATION */
+
+
static void free_section(struct sframe_section *sec)
{
dbg_free(sec);
@@ -460,6 +553,10 @@ int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end,
goto err_free;
}
+ ret = sframe_validate_section(sec);
+ if (ret)
+ goto err_free;
+
ret = mtree_insert_range(sframe_mt, sec->text_start, sec->text_end, sec, GFP_KERNEL);
if (ret) {
dbg_sec("mtree_insert_range failed: text=%lx-%lx\n",
--
2.48.1