From: Josh Poimboeuf <[email protected]> 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 <[email protected]> Cc: Mathieu Desnoyers <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Andrii Nakryiko <[email protected]> Cc: Indu Bhagat <[email protected]> Cc: "Jose E. Marchesi" <[email protected]> Cc: Beau Belgrave <[email protected]> Cc: Jens Remus <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Florian Weimer <[email protected]> Cc: Sam James <[email protected]> Cc: Kees Cook <[email protected]> Cc: "Carlos O'Donell" <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Steven Rostedt (Google) <[email protected]> Signed-off-by: Jens Remus <[email protected]> --- 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
