From: Anthony Yznaga <anthony.yznaga@oracle.com>
To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org
Cc: mhocko@kernel.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, x86@kernel.org, hpa@zytor.com,
viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
arnd@arndb.de, ebiederm@xmission.com, keescook@chromium.org,
gerg@linux-m68k.org, ktkhai@virtuozzo.com,
christian.brauner@ubuntu.com, peterz@infradead.org,
esyr@redhat.com, jgg@ziepe.ca, christian@kellner.me,
areber@redhat.com, cyphar@cyphar.com, steven.sistare@oracle.com
Subject: [RFC PATCH 4/5] exec, elf: require opt-in for accepting preserved mem
Date: Mon, 27 Jul 2020 10:11:26 -0700 [thread overview]
Message-ID: <1595869887-23307-5-git-send-email-anthony.yznaga@oracle.com> (raw)
In-Reply-To: <1595869887-23307-1-git-send-email-anthony.yznaga@oracle.com>
Don't copy preserved VMAs to the binary being exec'd unless the binary has
a "preserved-mem-ok" ELF note.
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
fs/binfmt_elf.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/exec.c | 17 +++++-----
include/linux/binfmts.h | 7 ++++-
3 files changed, 100 insertions(+), 8 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 6445a6dbdb1d..46248b7b0a75 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -683,6 +683,81 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
return error;
}
+#define NOTES_SZ SZ_1K
+#define PRESERVED_MEM_OK_STRING "preserved-mem-ok"
+#define SZ_PRESERVED_MEM_OK_STRING sizeof(PRESERVED_MEM_OK_STRING)
+
+static int parse_elf_note(struct linux_binprm *bprm, const char *data, size_t *off, size_t datasz)
+{
+ const struct elf_note *nhdr;
+ const char *name;
+ size_t o;
+
+ o = *off;
+ datasz -= o;
+
+ if (datasz < sizeof(*nhdr))
+ return -ENOEXEC;
+
+ nhdr = (const struct elf_note *)(data + o);
+ o += sizeof(*nhdr);
+ datasz -= sizeof(*nhdr);
+
+ /*
+ * Currently only the preserved-mem-ok elf note is of interest.
+ */
+ if (nhdr->n_type != 0x07c1feed)
+ goto next;
+
+ if (nhdr->n_namesz > SZ_PRESERVED_MEM_OK_STRING)
+ return -ENOEXEC;
+
+ name = data + o;
+ if (datasz < SZ_PRESERVED_MEM_OK_STRING ||
+ strncmp(name, PRESERVED_MEM_OK_STRING, SZ_PRESERVED_MEM_OK_STRING))
+ return -ENOEXEC;
+
+ bprm->accepts_preserved_mem = 1;
+
+next:
+ o += roundup(nhdr->n_namesz, 4) + roundup(nhdr->n_descsz, 4);
+ *off = o;
+
+ return 0;
+}
+
+static int parse_elf_notes(struct linux_binprm *bprm, struct elf_phdr *phdr)
+{
+ char *notes;
+ size_t notes_sz;
+ size_t off = 0;
+ int ret;
+
+ if (!phdr)
+ return 0;
+
+ notes_sz = phdr->p_filesz;
+ if ((notes_sz > NOTES_SZ) || (notes_sz < sizeof(struct elf_note)))
+ return -ENOEXEC;
+
+ notes = kvmalloc(notes_sz, GFP_KERNEL);
+ if (!notes)
+ return -ENOMEM;
+
+ ret = elf_read(bprm->file, notes, notes_sz, phdr->p_offset);
+ if (ret < 0)
+ goto out;
+
+ while (off < notes_sz) {
+ ret = parse_elf_note(bprm, notes, &off, notes_sz);
+ if (ret)
+ break;
+ }
+out:
+ kvfree(notes);
+ return ret;
+}
+
/*
* These are the functions used to load ELF style executables and shared
* libraries. There is no binary dependent code anywhere else.
@@ -801,6 +876,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
unsigned long error;
struct elf_phdr *elf_ppnt, *elf_phdata, *interp_elf_phdata = NULL;
struct elf_phdr *elf_property_phdata = NULL;
+ struct elf_phdr *elf_notes_phdata = NULL;
unsigned long elf_bss, elf_brk;
int bss_prot = 0;
int retval, i;
@@ -909,6 +985,10 @@ static int load_elf_binary(struct linux_binprm *bprm)
executable_stack = EXSTACK_DISABLE_X;
break;
+ case PT_NOTE:
+ elf_notes_phdata = elf_ppnt;
+ break;
+
case PT_LOPROC ... PT_HIPROC:
retval = arch_elf_pt_proc(elf_ex, elf_ppnt,
bprm->file, false,
@@ -970,6 +1050,10 @@ static int load_elf_binary(struct linux_binprm *bprm)
if (retval)
goto out_free_dentry;
+ retval = parse_elf_notes(bprm, elf_notes_phdata);
+ if (retval)
+ goto out_free_dentry;
+
/* Flush all traces of the currently running executable */
retval = begin_new_exec(bprm);
if (retval)
diff --git a/fs/exec.c b/fs/exec.c
index 1de09c4eef00..b2b046fec1f8 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1088,10 +1088,11 @@ static int vma_dup_some(struct mm_struct *old_mm, struct mm_struct *new_mm)
* On success, this function returns with the mutex
* exec_update_mutex locked.
*/
-static int exec_mmap(struct mm_struct *mm)
+static int exec_mmap(struct linux_binprm *bprm)
{
struct task_struct *tsk;
struct mm_struct *old_mm, *active_mm;
+ struct mm_struct *mm = bprm->mm;
int ret;
/* Notify parent that we're no longer interested in the old VM */
@@ -1118,11 +1119,13 @@ static int exec_mmap(struct mm_struct *mm)
mutex_unlock(&tsk->signal->exec_update_mutex);
return -EINTR;
}
- ret = vma_dup_some(old_mm, mm);
- if (ret) {
- mmap_read_unlock(old_mm);
- mutex_unlock(&tsk->signal->exec_update_mutex);
- return ret;
+ if (bprm->accepts_preserved_mem) {
+ ret = vma_dup_some(old_mm, mm);
+ if (ret) {
+ mmap_read_unlock(old_mm);
+ mutex_unlock(&tsk->signal->exec_update_mutex);
+ return ret;
+ }
}
}
@@ -1386,7 +1389,7 @@ int begin_new_exec(struct linux_binprm * bprm)
* Release all of the old mmap stuff
*/
acct_arg_size(bprm, 0);
- retval = exec_mmap(bprm->mm);
+ retval = exec_mmap(bprm);
if (retval)
goto out;
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 4a20b7517dd0..6a66589454c8 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -41,7 +41,12 @@ struct linux_binprm {
* Set when errors can no longer be returned to the
* original userspace.
*/
- point_of_no_return:1;
+ point_of_no_return:1,
+ /*
+ * Set if the binary being exec'd will accept memory marked
+ * for preservation by the outgoing process.
+ */
+ accepts_preserved_mem:1;
#ifdef __alpha__
unsigned int taso:1;
#endif
--
1.8.3.1
next prev parent reply other threads:[~2020-07-27 17:03 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 17:11 [RFC PATCH 0/5] madvise MADV_DOEXEC Anthony Yznaga
2020-07-27 17:07 ` Eric W. Biederman
2020-07-27 18:00 ` Steven Sistare
2020-07-28 13:40 ` Christian Brauner
2020-07-27 17:11 ` [RFC PATCH 1/5] elf: reintroduce using MAP_FIXED_NOREPLACE for elf executable mappings Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 2/5] mm: do not assume only the stack vma exists in setup_arg_pages() Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 3/5] mm: introduce VM_EXEC_KEEP Anthony Yznaga
2020-07-28 13:38 ` Eric W. Biederman
2020-07-28 17:44 ` Anthony Yznaga
2020-07-29 13:52 ` Kirill A. Shutemov
2020-07-29 23:20 ` Anthony Yznaga
2020-07-27 17:11 ` Anthony Yznaga [this message]
2020-07-27 17:11 ` [RFC PATCH 5/5] mm: introduce MADV_DOEXEC Anthony Yznaga
2020-07-28 13:22 ` Kirill Tkhai
2020-07-28 14:06 ` Steven Sistare
2020-07-28 11:34 ` [RFC PATCH 0/5] madvise MADV_DOEXEC Kirill Tkhai
2020-07-28 17:28 ` Anthony Yznaga
2020-07-28 14:23 ` Andy Lutomirski
2020-07-28 14:30 ` Steven Sistare
2020-07-30 15:22 ` Matthew Wilcox
2020-07-30 15:27 ` Christian Brauner
2020-07-30 15:34 ` Matthew Wilcox
2020-07-30 15:54 ` Christian Brauner
2020-07-31 9:12 ` Stefan Hajnoczi
2020-07-30 15:59 ` Steven Sistare
2020-07-30 17:12 ` Matthew Wilcox
2020-07-30 17:35 ` Steven Sistare
2020-07-30 17:49 ` Matthew Wilcox
2020-07-30 18:27 ` Steven Sistare
2020-07-30 21:58 ` Eric W. Biederman
2020-07-31 14:57 ` Steven Sistare
2020-07-31 15:27 ` Matthew Wilcox
2020-07-31 16:11 ` Steven Sistare
2020-07-31 16:56 ` Jason Gunthorpe
2020-07-31 17:15 ` Steven Sistare
2020-07-31 17:48 ` Jason Gunthorpe
2020-07-31 17:55 ` Steven Sistare
2020-07-31 17:23 ` Matthew Wilcox
2020-08-03 15:28 ` Eric W. Biederman
2020-08-03 15:42 ` James Bottomley
2020-08-03 20:03 ` Steven Sistare
[not found] ` <9371b8272fd84280ae40b409b260bab3@AcuMS.aculab.com>
2020-08-04 11:13 ` Matthew Wilcox
2020-08-03 19:29 ` Steven Sistare
2020-07-31 19:41 ` Steven Sistare
2021-07-08 9:52 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-07-08 12:48 ` Steven Sistare
2021-07-12 1:05 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-07-12 1:30 ` Matthew Wilcox
2021-07-13 0:57 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-08-13 19:49 ` Khalid Aziz
2021-08-14 20:07 ` David Laight
2021-08-16 0:26 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-08-16 8:07 ` David Laight
2021-08-16 6:54 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-08-16 8:02 ` David Hildenbrand
2021-08-16 12:07 ` Matthew Wilcox
2021-08-16 12:20 ` David Hildenbrand
2021-08-16 12:42 ` David Hildenbrand
2021-08-16 12:46 ` Matthew Wilcox
2021-08-16 13:24 ` David Hildenbrand
2021-08-16 13:32 ` Matthew Wilcox
2021-08-16 14:10 ` David Hildenbrand
2021-08-16 14:27 ` Matthew Wilcox
2021-08-16 14:33 ` David Hildenbrand
2021-08-16 14:40 ` Matthew Wilcox
2021-08-16 15:01 ` David Hildenbrand
2021-08-16 15:59 ` Matthew Wilcox
2021-08-16 16:06 ` Khalid Aziz
2021-08-16 16:15 ` Matthew Wilcox
2021-08-16 16:13 ` David Hildenbrand
2021-08-16 12:27 ` [private] " David Hildenbrand
2021-08-16 12:30 ` David Hildenbrand
2021-08-17 0:47 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-08-17 0:55 ` Matthew Wilcox
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