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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Paul Wise <pabs3@bonedaddy.net>, Jakub Wilk <jwilk@jwilk.net>,
	Neil Horman <nhorman@tuxdriver.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Sasha Levin <sashal@kernel.org>,
	linux-fsdevel@vger.kernel.org
Subject: [PATCH AUTOSEL 5.2 57/59] coredump: split pipe command whitespace before expanding template
Date: Tue,  6 Aug 2019 17:33:17 -0400	[thread overview]
Message-ID: <20190806213319.19203-57-sashal@kernel.org> (raw)
In-Reply-To: <20190806213319.19203-1-sashal@kernel.org>

From: Paul Wise <pabs3@bonedaddy.net>

[ Upstream commit 315c69261dd3fa12dbc830d4fa00d1fad98d3b03 ]

Save the offsets of the start of each argument to avoid having to update
pointers to each argument after every corename krealloc and to avoid
having to duplicate the memory for the dump command.

Executable names containing spaces were previously being expanded from
%e or %E and then split in the middle of the filename.  This is
incorrect behaviour since an argument list can represent arguments with
spaces.

The splitting could lead to extra arguments being passed to the core
dump handler that it might have interpreted as options or ignored
completely.

Core dump handlers that are not aware of this Linux kernel issue will be
using %e or %E without considering that it may be split and so they will
be vulnerable to processes with spaces in their names breaking their
argument list.  If their internals are otherwise well written, such as
if they are written in shell but quote arguments, they will work better
after this change than before.  If they are not well written, then there
is a slight chance of breakage depending on the details of the code but
they will already be fairly broken by the split filenames.

Core dump handlers that are aware of this Linux kernel issue will be
placing %e or %E as the last item in their core_pattern and then
aggregating all of the remaining arguments into one, separated by
spaces.  Alternatively they will be obtaining the filename via other
methods.  Both of these will be compatible with the new arrangement.

A side effect from this change is that unknown template types (for
example %z) result in an empty argument to the dump handler instead of
the argument being dropped.  This is a desired change as:

It is easier for dump handlers to process empty arguments than dropped
ones, especially if they are written in shell or don't pass each
template item with a preceding command-line option in order to
differentiate between individual template types.  Most core_patterns in
the wild do not use options so they can confuse different template types
(especially numeric ones) if an earlier one gets dropped in old kernels.
If the kernel introduces a new template type and a core_pattern uses it,
the core dump handler might not expect that the argument can be dropped
in old kernels.

For example, this can result in security issues when %d is dropped in
old kernels.  This happened with the corekeeper package in Debian and
resulted in the interface between corekeeper and Linux having to be
rewritten to use command-line options to differentiate between template
types.

The core_pattern for most core dump handlers is written by the handler
author who would generally not insert unknown template types so this
change should be compatible with all the core dump handlers that exist.

Link: http://lkml.kernel.org/r/20190528051142.24939-1-pabs3@bonedaddy.net
Fixes: 74aadce98605 ("core_pattern: allow passing of arguments to user mode helper when core_pattern is a pipe")
Signed-off-by: Paul Wise <pabs3@bonedaddy.net>
Reported-by: Jakub Wilk <jwilk@jwilk.net> [https://bugs.debian.org/924398]
Reported-by: Paul Wise <pabs3@bonedaddy.net> [https://lore.kernel.org/linux-fsdevel/c8b7ecb8508895bf4adb62a748e2ea2c71854597.camel@bonedaddy.net/]
Suggested-by: Jakub Wilk <jwilk@jwilk.net>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/coredump.c | 44 +++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 39 insertions(+), 5 deletions(-)

diff --git a/fs/coredump.c b/fs/coredump.c
index e42e17e55bfd5..b1ea7dfbd1494 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -7,6 +7,7 @@
 #include <linux/stat.h>
 #include <linux/fcntl.h>
 #include <linux/swap.h>
+#include <linux/ctype.h>
 #include <linux/string.h>
 #include <linux/init.h>
 #include <linux/pagemap.h>
@@ -187,11 +188,13 @@ static int cn_print_exe_file(struct core_name *cn)
  * name into corename, which must have space for at least
  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
  */
-static int format_corename(struct core_name *cn, struct coredump_params *cprm)
+static int format_corename(struct core_name *cn, struct coredump_params *cprm,
+			   size_t **argv, int *argc)
 {
 	const struct cred *cred = current_cred();
 	const char *pat_ptr = core_pattern;
 	int ispipe = (*pat_ptr == '|');
+	bool was_space = false;
 	int pid_in_pattern = 0;
 	int err = 0;
 
@@ -201,12 +204,35 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm)
 		return -ENOMEM;
 	cn->corename[0] = '\0';
 
-	if (ispipe)
+	if (ispipe) {
+		int argvs = sizeof(core_pattern) / 2;
+		(*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL);
+		if (!(*argv))
+			return -ENOMEM;
+		(*argv)[(*argc)++] = 0;
 		++pat_ptr;
+	}
 
 	/* Repeat as long as we have more pattern to process and more output
 	   space */
 	while (*pat_ptr) {
+		/*
+		 * Split on spaces before doing template expansion so that
+		 * %e and %E don't get split if they have spaces in them
+		 */
+		if (ispipe) {
+			if (isspace(*pat_ptr)) {
+				was_space = true;
+				pat_ptr++;
+				continue;
+			} else if (was_space) {
+				was_space = false;
+				err = cn_printf(cn, "%c", '\0');
+				if (err)
+					return err;
+				(*argv)[(*argc)++] = cn->used;
+			}
+		}
 		if (*pat_ptr != '%') {
 			err = cn_printf(cn, "%c", *pat_ptr++);
 		} else {
@@ -546,6 +572,8 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 	struct cred *cred;
 	int retval = 0;
 	int ispipe;
+	size_t *argv = NULL;
+	int argc = 0;
 	struct files_struct *displaced;
 	/* require nonrelative corefile path and be extra careful */
 	bool need_suid_safe = false;
@@ -592,9 +620,10 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 
 	old_cred = override_creds(cred);
 
-	ispipe = format_corename(&cn, &cprm);
+	ispipe = format_corename(&cn, &cprm, &argv, &argc);
 
 	if (ispipe) {
+		int argi;
 		int dump_count;
 		char **helper_argv;
 		struct subprocess_info *sub_info;
@@ -637,12 +666,16 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 			goto fail_dropcount;
 		}
 
-		helper_argv = argv_split(GFP_KERNEL, cn.corename, NULL);
+		helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv),
+					    GFP_KERNEL);
 		if (!helper_argv) {
 			printk(KERN_WARNING "%s failed to allocate memory\n",
 			       __func__);
 			goto fail_dropcount;
 		}
+		for (argi = 0; argi < argc; argi++)
+			helper_argv[argi] = cn.corename + argv[argi];
+		helper_argv[argi] = NULL;
 
 		retval = -ENOMEM;
 		sub_info = call_usermodehelper_setup(helper_argv[0],
@@ -652,7 +685,7 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 			retval = call_usermodehelper_exec(sub_info,
 							  UMH_WAIT_EXEC);
 
-		argv_free(helper_argv);
+		kfree(helper_argv);
 		if (retval) {
 			printk(KERN_INFO "Core dump to |%s pipe failed\n",
 			       cn.corename);
@@ -766,6 +799,7 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 	if (ispipe)
 		atomic_dec(&core_dump_count);
 fail_unlock:
+	kfree(argv);
 	kfree(cn.corename);
 	coredump_finish(mm, core_dumped);
 	revert_creds(old_cred);
-- 
2.20.1


  parent reply	other threads:[~2019-08-06 21:42 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-06 21:32 [PATCH AUTOSEL 5.2 01/59] RDMA/hns: Fix sg offset non-zero issue Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 02/59] IB/mlx5: Replace kfree with kvfree Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 03/59] clk: at91: generated: Truncate divisor to GENERATED_MAX_DIV + 1 Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 04/59] clk: sprd: Select REGMAP_MMIO to avoid compile errors Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 05/59] clk: renesas: cpg-mssr: Fix reset control race condition Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 06/59] dma-mapping: check pfn validity in dma_common_{mmap,get_sgtable} Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 07/59] xtensa: fix build for cores with coprocessors Sasha Levin
2019-08-06 21:55   ` Max Filippov
2019-08-18  1:45     ` Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 08/59] platform/x86: pcengines-apuv2: Fix softdep statement Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 09/59] platform/x86: intel_pmc_core: Add ICL-NNPI support to PMC Core Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 10/59] mm/hmm: always return EBUSY for invalid ranges in hmm_range_{fault,snapshot} Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 11/59] xen/pciback: remove set but not used variable 'old_state' Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 12/59] irqchip/gic-v3-its: Free unused vpt_page when alloc vpe table fail Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 13/59] irqchip/irq-imx-gpcv2: Forward irq type to parent Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 14/59] f2fs: fix to read source block before invalidating it Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 15/59] tools perf beauty: Fix usbdevfs_ioctl table generator to handle _IOC() Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 16/59] perf header: Fix divide by zero error if f_header.attr_size==0 Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 17/59] perf header: Fix use of unitialized value warning Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 18/59] RDMA/qedr: Fix the hca_type and hca_rev returned in device attributes Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 19/59] ALSA: pcm: fix lost wakeup event scenarios in snd_pcm_drain Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 20/59] libata: zpodd: Fix small read overflow in zpodd_get_mech_type() Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 21/59] powerpc/nvdimm: Pick nearby online node if the device node is not online Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 22/59] drm/bridge: lvds-encoder: Fix build error while CONFIG_DRM_KMS_HELPER=m Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 23/59] drm/bridge: tc358764: Fix build error Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 24/59] Btrfs: fix deadlock between fiemap and transaction commits Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 25/59] scsi: hpsa: correct scsi command status issue after reset Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 26/59] scsi: qla2xxx: Fix possible fcport null-pointer dereferences Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 27/59] exit: make setting exit_state consistent Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 28/59] tracing: Fix header include guards in trace event headers Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 29/59] drm/amdkfd: Fix byte align on VegaM Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 30/59] drm/amd/powerplay: fix null pointer dereference around dpm state relates Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 31/59] drm/amdgpu: fix error handling in amdgpu_cs_process_fence_dep Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 32/59] drm/amdgpu: fix a potential information leaking bug Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 33/59] ata: libahci: do not complain in case of deferred probe Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 34/59] kbuild: modpost: handle KBUILD_EXTRA_SYMBOLS only for external modules Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 35/59] kbuild: Check for unknown options with cc-option usage in Kconfig and clang Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 36/59] arm64/efi: fix variable 'si' set but not used Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 37/59] drm/vgem: fix cache synchronization on arm/arm64 Sasha Levin
2019-08-06 22:45   ` Rob Clark
2019-08-18  1:45     ` Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 38/59] riscv: Fix perf record without libelf support Sasha Levin
2019-08-06 21:32 ` [PATCH AUTOSEL 5.2 39/59] i2c: iproc: Fix i2c master read more than 63 bytes Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 40/59] arm64: Lower priority mask for GIC_PRIO_IRQON Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 41/59] arm64: unwind: Prohibit probing on return_address() Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 42/59] arm64/mm: fix variable 'pud' set but not used Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 43/59] arm64/mm: fix variable 'tag' " Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 44/59] IB/core: Add mitigation for Spectre V1 Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 45/59] IB/mlx5: Fix MR registration flow to use UMR properly Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 46/59] RDMA/restrack: Track driver QP types in resource tracker Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 47/59] IB/mad: Fix use-after-free in ib mad completion handling Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 48/59] RDMA/mlx5: Release locks during notifier unregister Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 49/59] drm: msm: Fix add_gpu_components Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 50/59] RDMA/hns: Fix error return code in hns_roce_v1_rsv_lp_qp() Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 51/59] drm/exynos: fix missing decrement of retry counter Sasha Levin
2019-08-07  8:49   ` David Laight
2019-08-18  1:47     ` Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 52/59] arm64: kprobes: Recover pstate.D in single-step exception handler Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 53/59] arm64: Make debug exception handlers visible from RCU Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 54/59] Revert "kmemleak: allow to coexist with fault injection" Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 55/59] ocfs2: remove set but not used variable 'last_hash' Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 56/59] page flags: prioritize kasan bits over last-cpuid Sasha Levin
2019-08-06 21:33 ` Sasha Levin [this message]
2019-08-07  1:41   ` [PATCH AUTOSEL 5.2 57/59] coredump: split pipe command whitespace before expanding template Paul Wise
2019-08-18  1:48     ` Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 58/59] asm-generic: fix -Wtype-limits compiler warnings Sasha Levin
2019-08-06 21:33 ` [PATCH AUTOSEL 5.2 59/59] tpm: tpm_ibm_vtpm: Fix unallocated banks Sasha Levin

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