[PATCH RESEND v3 0/2] fix RLIMIT_CORE accounting for sparse dumps

[PATCH RESEND v3 0/2] fix RLIMIT_CORE accounting for sparse dumps

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

Al, could you please apply this series for v4.7? I first sent it out
during the v4.5 cycle, it'd be great to be done with it, especially
since it's fixing a regression.

Here's the cover letter from v1:
http://www.spinics.net/lists/linux-fsdevel/msg94735.html

Omar Sandoval (2):
  coredump: get rid of coredump_params->written
  coredump: only charge written data against RLIMIT_CORE

 arch/powerpc/platforms/cell/spufs/coredump.c | 5 +++--
 fs/binfmt_elf.c                              | 2 +-
 fs/binfmt_elf_fdpic.c                        | 2 +-
 fs/coredump.c                                | 5 +----
 4 files changed, 6 insertions(+), 8 deletions(-)

-- 
2.8.2

[PATCH RESEND v3 1/2] coredump: get rid of coredump_params->written

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

cprm->written is redundant with cprm->file->f_pos, so use that instead.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 arch/powerpc/platforms/cell/spufs/coredump.c | 5 +++--
 fs/binfmt_elf.c                              | 2 +-
 fs/binfmt_elf_fdpic.c                        | 2 +-
 fs/coredump.c                                | 8 +++-----
 include/linux/binfmts.h                      | 1 -
 5 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spufs/coredump.c b/arch/powerpc/platforms/cell/spufs/coredump.c
index be6212ddbf06..84fb984f29c1 100644
--- a/arch/powerpc/platforms/cell/spufs/coredump.c
+++ b/arch/powerpc/platforms/cell/spufs/coredump.c
@@ -137,6 +137,7 @@ static int spufs_arch_write_note(struct spu_context *ctx, int i,
 	char *name;
 	char fullname[80], *buf;
 	struct elf_note en;
+	size_t skip;
 
 	buf = (void *)get_zeroed_page(GFP_KERNEL);
 	if (!buf)
@@ -171,8 +172,8 @@ static int spufs_arch_write_note(struct spu_context *ctx, int i,
 	if (rc < 0)
 		goto out;
 
-	if (!dump_skip(cprm,
-		       roundup(cprm->written - total + sz, 4) - cprm->written))
+	skip = roundup(cprm->file->f_pos - total + sz, 4) - cprm->file->f_pos;
+	if (!dump_skip(cprm, skip))
 		goto Eio;
 out:
 	free_page((unsigned long)buf);
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 81381cc0dd17..56224ffa94d2 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2273,7 +2273,7 @@ static int elf_core_dump(struct coredump_params *cprm)
 		goto end_coredump;
 
 	/* Align to page */
-	if (!dump_skip(cprm, dataoff - cprm->written))
+	if (!dump_skip(cprm, dataoff - cprm->file->f_pos))
 		goto end_coredump;
 
 	for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 083ea2bc60ab..71ade0e556b7 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1787,7 +1787,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 				goto end_coredump;
 	}
 
-	if (!dump_skip(cprm, dataoff - cprm->written))
+	if (!dump_skip(cprm, dataoff - cprm->file->f_pos))
 		goto end_coredump;
 
 	if (!elf_fdpic_dump_segments(cprm))
diff --git a/fs/coredump.c b/fs/coredump.c
index 47c32c3bfa1d..9db0c514438e 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -782,7 +782,7 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
 	struct file *file = cprm->file;
 	loff_t pos = file->f_pos;
 	ssize_t n;
-	if (cprm->written + nr > cprm->limit)
+	if (pos + nr > cprm->limit)
 		return 0;
 	while (nr) {
 		if (dump_interrupted())
@@ -791,7 +791,6 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
 		if (n <= 0)
 			return 0;
 		file->f_pos = pos;
-		cprm->written += n;
 		nr -= n;
 	}
 	return 1;
@@ -803,12 +802,11 @@ int dump_skip(struct coredump_params *cprm, size_t nr)
 	static char zeroes[PAGE_SIZE];
 	struct file *file = cprm->file;
 	if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
-		if (cprm->written + nr > cprm->limit)
+		if (file->f_pos + nr > cprm->limit)
 			return 0;
 		if (dump_interrupted() ||
 		    file->f_op->llseek(file, nr, SEEK_CUR) < 0)
 			return 0;
-		cprm->written += nr;
 		return 1;
 	} else {
 		while (nr > PAGE_SIZE) {
@@ -823,7 +821,7 @@ EXPORT_SYMBOL(dump_skip);
 
 int dump_align(struct coredump_params *cprm, int align)
 {
-	unsigned mod = cprm->written & (align - 1);
+	unsigned mod = cprm->file->f_pos & (align - 1);
 	if (align & (align - 1))
 		return 0;
 	return mod ? dump_skip(cprm, align - mod) : 1;
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 576e4639ca60..39c6d6e1234e 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -64,7 +64,6 @@ struct coredump_params {
 	struct file *file;
 	unsigned long limit;
 	unsigned long mm_flags;
-	loff_t written;
 };
 
 /*
-- 
2.8.2

[PATCH RESEND v3 2/2] coredump: only charge written data against RLIMIT_CORE

[Omar Sandoval]

From: Omar Sandoval <osandov@fb.com>

Commit 9b56d54380ad ("dump_skip(): dump_seek() replacement taking
coredump_params") introduced a regression with regard to RLIMIT_CORE.
Previously, when a core dump was sparse, only the data that was actually
written out would count against the limit. Now, the sparse ranges are
also included, which leads to truncated core dumps when the actual disk
usage is still well below the limit. Restore the old behavior by only
counting what gets emitted and ignoring what gets skipped.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 fs/coredump.c           | 5 ++---
 include/linux/binfmts.h | 1 +
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/coredump.c b/fs/coredump.c
index 9db0c514438e..492c2db25dc9 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -782,7 +782,7 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
 	struct file *file = cprm->file;
 	loff_t pos = file->f_pos;
 	ssize_t n;
-	if (pos + nr > cprm->limit)
+	if (cprm->written + nr > cprm->limit)
 		return 0;
 	while (nr) {
 		if (dump_interrupted())
@@ -791,6 +791,7 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
 		if (n <= 0)
 			return 0;
 		file->f_pos = pos;
+		cprm->written += n;
 		nr -= n;
 	}
 	return 1;
@@ -802,8 +803,6 @@ int dump_skip(struct coredump_params *cprm, size_t nr)
 	static char zeroes[PAGE_SIZE];
 	struct file *file = cprm->file;
 	if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
-		if (file->f_pos + nr > cprm->limit)
-			return 0;
 		if (dump_interrupted() ||
 		    file->f_op->llseek(file, nr, SEEK_CUR) < 0)
 			return 0;
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 39c6d6e1234e..576e4639ca60 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -64,6 +64,7 @@ struct coredump_params {
 	struct file *file;
 	unsigned long limit;
 	unsigned long mm_flags;
+	loff_t written;
 };
 
 /*
-- 
2.8.2

Re: [PATCH RESEND v3 0/2] fix RLIMIT_CORE accounting for sparse dumps

[Al Viro]

On Wed, May 11, 2016 at 03:16:35PM -0700, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> Al, could you please apply this series for v4.7? I first sent it out
> during the v4.5 cycle, it'd be great to be done with it, especially
> since it's fixing a regression.

Applied.