From: Jeff Xu jeffxu@google.com
When sysctl vm.memfd_noexec is 2 (MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED), memfd_create(.., MFD_EXEC) should fail.
This complies with how MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED is defined - "memfd_create() without MFD_NOEXEC_SEAL will be rejected"
Thanks to Dominique Martinet asmadeus@codewreck.org who reported the bug. see [1] for context.
[1] https://lore.kernel.org/linux-mm/CABi2SkXUX_QqTQ10Yx9bBUGpN1wByOi_=gZU6WEy5a...
Jeff Xu (2): mm/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED selftests/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED
mm/memfd.c | 48 +++++++++++----------- tools/testing/selftests/memfd/memfd_test.c | 5 +++ 2 files changed, 30 insertions(+), 23 deletions(-)
From: Jeff Xu jeffxu@google.com
When vm.memfd_noexec is 2 (MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED), memfd_create(.., MFD_EXEC) should fail.
This complies with how MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED is defined - "memfd_create() without MFD_NOEXEC_SEAL will be rejected"
Link:https://lore.kernel.org/linux-mm/CABi2SkXUX_QqTQ10Yx9bBUGpN1wByOi_=gZU6WEy5a... Fixes: 105ff5339f49 ("mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC") Reported-by: Dominique Martinet asmadeus@codewreck.org Signed-off-by: Jeff Xu jeffxu@google.com --- mm/memfd.c | 48 +++++++++++++++++++++++++----------------------- 1 file changed, 25 insertions(+), 23 deletions(-)
diff --git a/mm/memfd.c b/mm/memfd.c index e763e76f1106..812750298e8a 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -268,6 +268,19 @@ long memfd_fcntl(struct file *file, unsigned int cmd, unsigned int arg)
#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB | MFD_NOEXEC_SEAL | MFD_EXEC)
+static int sysctl_memfd_noexec(void) +{ + int sysctl = MEMFD_NOEXEC_SCOPE_EXEC; +#ifdef CONFIG_SYSCTL + struct pid_namespace *ns; + + ns = task_active_pid_ns(current); + if (ns) + sysctl = ns->memfd_noexec_scope; +#endif + return sysctl; +} + SYSCALL_DEFINE2(memfd_create, const char __user *, uname, unsigned int, flags) @@ -278,6 +291,7 @@ SYSCALL_DEFINE2(memfd_create, int fd, error; char *name; long len; + int sysctl = sysctl_memfd_noexec();
if (!(flags & MFD_HUGETLB)) { if (flags & ~(unsigned int)MFD_ALL_FLAGS) @@ -294,35 +308,23 @@ SYSCALL_DEFINE2(memfd_create, return -EINVAL;
if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) { -#ifdef CONFIG_SYSCTL - int sysctl = MEMFD_NOEXEC_SCOPE_EXEC; - struct pid_namespace *ns; - - ns = task_active_pid_ns(current); - if (ns) - sysctl = ns->memfd_noexec_scope; - - switch (sysctl) { - case MEMFD_NOEXEC_SCOPE_EXEC: - flags |= MFD_EXEC; - break; - case MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL: + if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL) flags |= MFD_NOEXEC_SEAL; - break; - default: - pr_warn_once( - "memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n", - task_pid_nr(current), get_task_comm(comm, current)); - return -EINVAL; - } -#else - flags |= MFD_EXEC; -#endif + else + flags |= MFD_EXEC; + pr_warn_once( "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n", task_pid_nr(current), get_task_comm(comm, current)); }
+ if (flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) { + pr_warn_once( + "memfd_create(): MFD_NOEXEC_SEAL is enforced, pid=%d '%s'\n", + task_pid_nr(current), get_task_comm(comm, current)); + return -EACCES; + } + /* length includes terminating zero */ len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1); if (len <= 0)
Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/jeffxu-chromium-org/mm-memfd-... base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/20230630031721.623955-2-jeffxu%40google.com patch subject: [PATCH v1 1/2] mm/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED config: microblaze-randconfig-r003-20230630 (https://download.01.org/0day-ci/archive/20230630/202306301351.kkbSegQW-lkp@i...) compiler: microblaze-linux-gcc (GCC) 12.3.0 reproduce: (https://download.01.org/0day-ci/archive/20230630/202306301351.kkbSegQW-lkp@i...)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202306301351.kkbSegQW-lkp@intel.com/
All errors (new ones prefixed by >>):
mm/memfd.c: In function 'sysctl_memfd_noexec':
mm/memfd.c:273:22: error: 'MEMFD_NOEXEC_SCOPE_EXEC' undeclared (first use in this function)
273 | int sysctl = MEMFD_NOEXEC_SCOPE_EXEC; | ^~~~~~~~~~~~~~~~~~~~~~~ mm/memfd.c:273:22: note: each undeclared identifier is reported only once for each function it appears in mm/memfd.c: In function '__do_sys_memfd_create':
mm/memfd.c:311:31: error: 'MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL' undeclared (first use in this function)
311 | if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/memfd.c:321:43: error: 'MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED' undeclared (first use in this function)
321 | if (flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
vim +/MEMFD_NOEXEC_SCOPE_EXEC +273 mm/memfd.c
270 271 static int sysctl_memfd_noexec(void) 272 {
273 int sysctl = MEMFD_NOEXEC_SCOPE_EXEC;
274 #ifdef CONFIG_SYSCTL 275 struct pid_namespace *ns; 276 277 ns = task_active_pid_ns(current); 278 if (ns) 279 sysctl = ns->memfd_noexec_scope; 280 #endif 281 return sysctl; 282 } 283 284 SYSCALL_DEFINE2(memfd_create, 285 const char __user *, uname, 286 unsigned int, flags) 287 { 288 char comm[TASK_COMM_LEN]; 289 unsigned int *file_seals; 290 struct file *file; 291 int fd, error; 292 char *name; 293 long len; 294 int sysctl = sysctl_memfd_noexec(); 295 296 if (!(flags & MFD_HUGETLB)) { 297 if (flags & ~(unsigned int)MFD_ALL_FLAGS) 298 return -EINVAL; 299 } else { 300 /* Allow huge page size encoding in flags. */ 301 if (flags & ~(unsigned int)(MFD_ALL_FLAGS | 302 (MFD_HUGE_MASK << MFD_HUGE_SHIFT))) 303 return -EINVAL; 304 } 305 306 /* Invalid if both EXEC and NOEXEC_SEAL are set.*/ 307 if ((flags & MFD_EXEC) && (flags & MFD_NOEXEC_SEAL)) 308 return -EINVAL; 309 310 if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
311 if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL)
312 flags |= MFD_NOEXEC_SEAL; 313 else 314 flags |= MFD_EXEC; 315 316 pr_warn_once( 317 "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n", 318 task_pid_nr(current), get_task_comm(comm, current)); 319 } 320
321 if (flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) {
Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/jeffxu-chromium-org/mm-memfd-... base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/20230630031721.623955-2-jeffxu%40google.com patch subject: [PATCH v1 1/2] mm/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED config: hexagon-randconfig-r005-20230630 (https://download.01.org/0day-ci/archive/20230630/202306301435.dpXv0GwQ-lkp@i...) compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a) reproduce: (https://download.01.org/0day-ci/archive/20230630/202306301435.dpXv0GwQ-lkp@i...)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202306301435.dpXv0GwQ-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from mm/memfd.c:12: In file included from include/linux/pagemap.h:11: In file included from include/linux/highmem.h:12: In file included from include/linux/hardirq.h:11: In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1: In file included from include/asm-generic/hardirq.h:17: In file included from include/linux/irq.h:20: In file included from include/linux/io.h:13: In file included from arch/hexagon/include/asm/io.h:334: include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] 547 | val = __raw_readb(PCI_IOBASE + addr); | ~~~~~~~~~~ ^ include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] 560 | val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr)); | ~~~~~~~~~~ ^ include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu' 37 | #define __le16_to_cpu(x) ((__force __u16)(__le16)(x)) | ^ In file included from mm/memfd.c:12: In file included from include/linux/pagemap.h:11: In file included from include/linux/highmem.h:12: In file included from include/linux/hardirq.h:11: In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1: In file included from include/asm-generic/hardirq.h:17: In file included from include/linux/irq.h:20: In file included from include/linux/io.h:13: In file included from arch/hexagon/include/asm/io.h:334: include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] 573 | val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr)); | ~~~~~~~~~~ ^ include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu' 35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x)) | ^ In file included from mm/memfd.c:12: In file included from include/linux/pagemap.h:11: In file included from include/linux/highmem.h:12: In file included from include/linux/hardirq.h:11: In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1: In file included from include/asm-generic/hardirq.h:17: In file included from include/linux/irq.h:20: In file included from include/linux/io.h:13: In file included from arch/hexagon/include/asm/io.h:334: include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] 584 | __raw_writeb(value, PCI_IOBASE + addr); | ~~~~~~~~~~ ^ include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] 594 | __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr); | ~~~~~~~~~~ ^ include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] 604 | __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr); | ~~~~~~~~~~ ^
mm/memfd.c:273:15: error: use of undeclared identifier 'MEMFD_NOEXEC_SCOPE_EXEC'
273 | int sysctl = MEMFD_NOEXEC_SCOPE_EXEC; | ^
mm/memfd.c:311:17: error: use of undeclared identifier 'MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL'
311 | if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL) | ^
mm/memfd.c:321:36: error: use of undeclared identifier 'MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED'
321 | if (flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) { | ^ 6 warnings and 3 errors generated.
vim +/MEMFD_NOEXEC_SCOPE_EXEC +273 mm/memfd.c
270 271 static int sysctl_memfd_noexec(void) 272 {
273 int sysctl = MEMFD_NOEXEC_SCOPE_EXEC;
274 #ifdef CONFIG_SYSCTL 275 struct pid_namespace *ns; 276 277 ns = task_active_pid_ns(current); 278 if (ns) 279 sysctl = ns->memfd_noexec_scope; 280 #endif 281 return sysctl; 282 } 283 284 SYSCALL_DEFINE2(memfd_create, 285 const char __user *, uname, 286 unsigned int, flags) 287 { 288 char comm[TASK_COMM_LEN]; 289 unsigned int *file_seals; 290 struct file *file; 291 int fd, error; 292 char *name; 293 long len; 294 int sysctl = sysctl_memfd_noexec(); 295 296 if (!(flags & MFD_HUGETLB)) { 297 if (flags & ~(unsigned int)MFD_ALL_FLAGS) 298 return -EINVAL; 299 } else { 300 /* Allow huge page size encoding in flags. */ 301 if (flags & ~(unsigned int)(MFD_ALL_FLAGS | 302 (MFD_HUGE_MASK << MFD_HUGE_SHIFT))) 303 return -EINVAL; 304 } 305 306 /* Invalid if both EXEC and NOEXEC_SEAL are set.*/ 307 if ((flags & MFD_EXEC) && (flags & MFD_NOEXEC_SEAL)) 308 return -EINVAL; 309 310 if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
311 if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL)
312 flags |= MFD_NOEXEC_SEAL; 313 else 314 flags |= MFD_EXEC; 315 316 pr_warn_once( 317 "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n", 318 task_pid_nr(current), get_task_comm(comm, current)); 319 } 320
321 if (flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) {
Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/jeffxu-chromium-org/mm-memfd-... base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/20230630031721.623955-2-jeffxu%40google.com patch subject: [PATCH v1 1/2] mm/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED config: riscv-randconfig-r042-20230630 (https://download.01.org/0day-ci/archive/20230630/202306301413.VtwSCI1F-lkp@i...) compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a) reproduce: (https://download.01.org/0day-ci/archive/20230630/202306301413.VtwSCI1F-lkp@i...)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202306301413.VtwSCI1F-lkp@intel.com/
All errors (new ones prefixed by >>):
mm/memfd.c:273:15: error: use of undeclared identifier 'MEMFD_NOEXEC_SCOPE_EXEC'
273 | int sysctl = MEMFD_NOEXEC_SCOPE_EXEC; | ^
mm/memfd.c:311:17: error: use of undeclared identifier 'MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL'
311 | if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL) | ^
mm/memfd.c:321:36: error: use of undeclared identifier 'MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED'
321 | if (flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) { | ^ 3 errors generated.
vim +/MEMFD_NOEXEC_SCOPE_EXEC +273 mm/memfd.c
270 271 static int sysctl_memfd_noexec(void) 272 {
273 int sysctl = MEMFD_NOEXEC_SCOPE_EXEC;
274 #ifdef CONFIG_SYSCTL 275 struct pid_namespace *ns; 276 277 ns = task_active_pid_ns(current); 278 if (ns) 279 sysctl = ns->memfd_noexec_scope; 280 #endif 281 return sysctl; 282 } 283 284 SYSCALL_DEFINE2(memfd_create, 285 const char __user *, uname, 286 unsigned int, flags) 287 { 288 char comm[TASK_COMM_LEN]; 289 unsigned int *file_seals; 290 struct file *file; 291 int fd, error; 292 char *name; 293 long len; 294 int sysctl = sysctl_memfd_noexec(); 295 296 if (!(flags & MFD_HUGETLB)) { 297 if (flags & ~(unsigned int)MFD_ALL_FLAGS) 298 return -EINVAL; 299 } else { 300 /* Allow huge page size encoding in flags. */ 301 if (flags & ~(unsigned int)(MFD_ALL_FLAGS | 302 (MFD_HUGE_MASK << MFD_HUGE_SHIFT))) 303 return -EINVAL; 304 } 305 306 /* Invalid if both EXEC and NOEXEC_SEAL are set.*/ 307 if ((flags & MFD_EXEC) && (flags & MFD_NOEXEC_SEAL)) 308 return -EINVAL; 309 310 if (!(flags & (MFD_EXEC | MFD_NOEXEC_SEAL))) {
311 if (sysctl == MEMFD_NOEXEC_SCOPE_NOEXEC_SEAL)
312 flags |= MFD_NOEXEC_SEAL; 313 else 314 flags |= MFD_EXEC; 315 316 pr_warn_once( 317 "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=%d '%s'\n", 318 task_pid_nr(current), get_task_comm(comm, current)); 319 } 320
321 if (flags & MFD_EXEC && sysctl >= MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED) {
From: Jeff Xu jeffxu@google.com
Add selftest for sysctl vm.memfd_noexec is 2 (MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED)
memfd_create(.., MFD_EXEC) should fail in this case.
Signed-off-by: Jeff Xu jeffxu@google.com --- tools/testing/selftests/memfd/memfd_test.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index dba0e8ba002f..dbdd9ec5e397 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -1147,6 +1147,11 @@ static void test_sysctl_child(void) sysctl_assert_write("2"); mfd_fail_new("kern_memfd_sysctl_2", MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_fail_new("kern_memfd_sysctl_2_MFD_EXEC", + MFD_CLOEXEC | MFD_EXEC); + fd = mfd_assert_new("", 0, MFD_NOEXEC_SEAL); + close(fd); + sysctl_fail_write("0"); sysctl_fail_write("1"); }
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