Merge branch 'vfs-7.4.coredump' into vfs.all

Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 145 insertions, 4 deletions

diff --git a/include/uapi/linux/coredump.h b/include/uapi/linux/coredump.h
index dc3789b78af0..6d0c53b534ea 100644
--- a/include/uapi/linux/coredump.h
+++ b/include/uapi/linux/coredump.h
@@ -11,12 +11,53 @@
  * @COREDUMP_USERSPACE: userspace writes coredump
  * @COREDUMP_REJECT: don't generate coredump
  * @COREDUMP_WAIT: wait for coredump server
+ * @COREDUMP_RECORDS: send the coredump as a sequence of records instead of
+ *                    as a plain byte stream, see struct coredump_record_header;
+ *                    requires COREDUMP_KERNEL
+ * @COREDUMP_SPARSE: describe the holes in the coredump as zero records
+ *                   instead of transferring them; requires COREDUMP_RECORDS
+ * @COREDUMP_MEMORY_TYPES: dump the memory types in
+ *                          coredump_ack->memory_types instead of the ones
+ *                          the task selected; requires COREDUMP_KERNEL
  */
 enum {
 	COREDUMP_KERNEL		= (1ULL << 0),
 	COREDUMP_USERSPACE	= (1ULL << 1),
 	COREDUMP_REJECT		= (1ULL << 2),
 	COREDUMP_WAIT		= (1ULL << 3),
+	COREDUMP_RECORDS	= (1ULL << 4),
+	COREDUMP_SPARSE		= (1ULL << 5),
+	COREDUMP_MEMORY_TYPES	= (1ULL << 6),
+};
+
+/**
+ * coredump memory types
+ * @COREDUMP_MEMORY_ANON_PRIVATE: anonymous private memory
+ * @COREDUMP_MEMORY_ANON_SHARED: anonymous shared memory
+ * @COREDUMP_MEMORY_FILE_PRIVATE: file-backed private memory
+ * @COREDUMP_MEMORY_FILE_SHARED: file-backed shared memory
+ * @COREDUMP_MEMORY_ELF_HEADERS: the first page of a file-backed private
+ *                               mapping that starts an ELF file
+ * @COREDUMP_MEMORY_HUGETLB_PRIVATE: hugetlb private memory
+ * @COREDUMP_MEMORY_HUGETLB_SHARED: hugetlb shared memory
+ * @COREDUMP_MEMORY_DAX_PRIVATE: DAX private memory
+ * @COREDUMP_MEMORY_DAX_SHARED: DAX shared memory
+ *
+ * A bitmask of memory types a coredump may request to be included. New
+ * memory type bits must ensure that they do not steal memory from an
+ * existing one so a coredump server will continue to get the same
+ * coredumps even if a new bit is introduced.
+ */
+enum {
+	COREDUMP_MEMORY_ANON_PRIVATE	= (1ULL << 0),
+	COREDUMP_MEMORY_ANON_SHARED	= (1ULL << 1),
+	COREDUMP_MEMORY_FILE_PRIVATE	= (1ULL << 2),
+	COREDUMP_MEMORY_FILE_SHARED	= (1ULL << 3),
+	COREDUMP_MEMORY_ELF_HEADERS	= (1ULL << 4),
+	COREDUMP_MEMORY_HUGETLB_PRIVATE	= (1ULL << 5),
+	COREDUMP_MEMORY_HUGETLB_SHARED	= (1ULL << 6),
+	COREDUMP_MEMORY_DAX_PRIVATE	= (1ULL << 7),
+	COREDUMP_MEMORY_DAX_SHARED	= (1ULL << 8),
 };
 
 /**
@@ -24,17 +65,19 @@ enum {
  * @size: size of struct coredump_req
  * @size_ack: known size of struct coredump_ack on this kernel
  * @mask: supported features
+ * @memory_types: the memory types the task selected
+ * @memory_types_mask: the memory types this kernel knows
  *
  * When a coredump happens the kernel will connect to the coredump
  * socket and send a coredump request to the coredump server. The @size
  * member is set to the size of struct coredump_req and provides a hint
  * to userspace how much data can be read. Userspace may use MSG_PEEK to
  * peek the size of struct coredump_req and then choose to consume it in
- * one go. Userspace may also simply read a COREDUMP_ACK_SIZE_VER0
+ * one go. Userspace may also simply read a COREDUMP_REQ_SIZE_VER0
  * request. If the size the kernel sends is larger userspace simply
  * discards any remaining data.
  *
- * The coredump_req->mask member is set to the currently know features.
+ * The coredump_req->mask member is set to the currently known features.
  * Userspace may only set coredump_ack->mask to the bits raised by the
  * kernel in coredump_req->mask.
  *
@@ -42,15 +85,27 @@ enum {
  * struct coredump_ack the kernel knows. Userspace may only send up to
  * coredump_req->size_ack bytes to the kernel and must set
  * coredump_ack->size accordingly.
+ *
+ * @memory_types is set to the default memory types that are included in
+ * the coredump. This can be overridden by raising bits in
+ * coredump_ack->memory_types.
+ *
+ * @memory_types_mask contains a bitmask of all memory types the kernel
+ * knows about. A coredump server may only raise bits in
+ * coredump_ack->memory_types that are raised in
+ * coredump_req->memory_types_mask.
  */
 struct coredump_req {
 	__u32 size;
 	__u32 size_ack;
 	__u64 mask;
+	__u64 memory_types;
+	__u64 memory_types_mask;
 };
 
 enum {
 	COREDUMP_REQ_SIZE_VER0 = 16U, /* size of first published struct */
+	COREDUMP_REQ_SIZE_VER1 = 32U, /* memory_types and memory_types_mask added */
 };
 
 /**
@@ -58,6 +113,8 @@ enum {
  * @size: size of the struct
  * @spare: unused
  * @mask: features kernel is supposed to use
+ * @memory_types: memory types to dump, only with COREDUMP_MEMORY_TYPES
+ *                 in @mask
  *
  * The @size member must be set to the size of struct coredump_ack. It
  * may never exceed what the kernel returned in coredump_req->size_ack
@@ -67,15 +124,30 @@ enum {
  * The @mask member must be set to the features the coredump server
  * wants the kernel to use. Only bits the kernel returned in
  * coredump_req->mask may be set.
+ *
+ * If COREDUMP_MEMORY_TYPES is raised in @mask the kernel dumps the
+ * memory types set in the @memory_types mask. Zero is valid and dumps
+ * no memory apart from the mappings that are always dumped.
+ *
+ * Note that memory a task excluded via MADV_DONTDUMP is always left
+ * out. A coredump server wanting to add or drop memory types instead of
+ * outright replacing it should simply copy coredump_req->memory_types
+ * and then mask off or raise types as needed.
+ *
+ * Note that @memory_types must be zero if COREDUMP_MEMORY_TYPES isn't
+ * raised. COREDUMP_MEMORY_TYPES requires COREDUMP_KERNEL and an ack of
+ * at least COREDUMP_ACK_SIZE_VER1 bytes.
  */
 struct coredump_ack {
 	__u32 size;
 	__u32 spare;
 	__u64 mask;
+	__u64 memory_types;
 };
 
 enum {
 	COREDUMP_ACK_SIZE_VER0 = 16U, /* size of first published struct */
+	COREDUMP_ACK_SIZE_VER1 = 24U, /* memory_types added */
 };
 
 /**
@@ -83,11 +155,12 @@ enum {
  *
  * The kernel will place a single byte on the coredump socket. The
  * markers notify userspace whether the coredump ack succeeded or
- * failed.
+ * failed. After any marker other than COREDUMP_MARK_REQACK the kernel
+ * closes the connection and no coredump is generated.
  *
  * @COREDUMP_MARK_MINSIZE: the provided coredump_ack size was too small
  * @COREDUMP_MARK_MAXSIZE: the provided coredump_ack size was too big
- * @COREDUMP_MARK_UNSUPPORTED: the provided coredump_ack mask was invalid
+ * @COREDUMP_MARK_UNSUPPORTED: the provided coredump_ack mask or memory types were invalid
  * @COREDUMP_MARK_CONFLICTING: the provided coredump_ack mask has conflicting options
  * @COREDUMP_MARK_REQACK: the coredump request and ack was successful
  * @__COREDUMP_MARK_MAX: the maximum coredump mark value
@@ -101,4 +174,72 @@ enum coredump_mark {
 	__COREDUMP_MARK_MAX		= (1U << 31),
 };
 
+/**
+ * enum coredump_record_type - Type of a coredump record
+ *
+ * @COREDUMP_RECORD_DATA: the header is followed by ->len bytes of data
+ * @COREDUMP_RECORD_END: the coredump ends here, the header is not followed
+ *                       by any data and no further record is sent
+ * @COREDUMP_RECORD_ZERO: the header stands for ->len zero bytes and is not
+ *                        followed by any data
+ * @__COREDUMP_RECORD_TYPE_MAX: the maximum coredump record type value
+ */
+enum coredump_record_type {
+	COREDUMP_RECORD_DATA		= 0U,
+	COREDUMP_RECORD_END		= 1U,
+	COREDUMP_RECORD_ZERO		= 2U,
+	__COREDUMP_RECORD_TYPE_MAX	= (1U << 31),
+};
+
+/**
+ * struct coredump_record_header - header of a coredump record
+ * @size: size of struct coredump_record_header
+ * @type: one of enum coredump_record_type
+ * @flags: modifiers for this record
+ * @offset: offset in the coredump this record starts at
+ * @len: number of coredump bytes this record accounts for
+ *
+ * If the coredump server raises COREDUMP_RECORDS in coredump_ack->mask
+ * the kernel doesn't send the coredump as a plain byte stream. It sends
+ * a sequence of records instead. A COREDUMP_RECORD_DATA record is
+ * followed by @len bytes of actual coredump data. A
+ * COREDUMP_RECORD_ZERO record is followed by nothing and stands for
+ * @len zero bytes. A server that didn't raise COREDUMP_SPARSE never
+ * sees a zero record. Records arrive in order and leave no gaps. So
+ * @offset is the sum of the @len of all records before it.
+ *
+ * The last record is a COREDUMP_RECORD_END record. It is followed by
+ * nothing. Its @len is zero. Its @offset is the size of the coredump.
+ * The kernel only sends it once it has written the whole coredump. A
+ * server that hits end-of-file without having seen an end record must
+ * treat the coredump as incomplete.
+ *
+ * The @size member is set to the size of struct coredump_record_header
+ * the kernel knows and lets the header grow later. It comes first so it
+ * can be peeked. Userspace must consume @size bytes and discard
+ * anything beyond what it knows. It must refuse a @size smaller than
+ * COREDUMP_RECORD_HEADER_SIZE_VER0. @size covers the header alone.
+ * @offset and @len count coredump bytes.
+ *
+ * The @flags member carries modifiers that change how the record is to
+ * be interpreted. No flag is defined yet. Userspace must refuse a
+ * record carrying a flag or a type it doesn't know. Every new record
+ * type is raised in coredump_req->mask as a feature of its own. A
+ * server only ever sees the types it asked for.
+ *
+ * COREDUMP_RECORDS must be combined with COREDUMP_KERNEL, and
+ * COREDUMP_SPARSE with COREDUMP_RECORDS.
+ */
+struct coredump_record_header {
+	__u32 size;
+	__u32 type;
+	__u64 flags;
+	__u64 offset;
+	__u64 len;
+};
+
+enum {
+	COREDUMP_RECORD_HEADER_SIZE_VER0 = 32U, /* size of first published struct */
+};
+
 #endif /* _UAPI_LINUX_COREDUMP_H */