Commit 853bc0ab authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

um: ubd: use 64-bit time_t where possible 



The ubd code suffers from a possible y2038 overflow on 32-bit
architectures, both for the cow header and the os_file_modtime()
function.

Replace time_t with time64_t to extend the ubd_kern side as much
as possible.

Whether this makes a difference for the user side depends on
the host libc implementation that may use either 32-bit or 64-bit
time_t.

For the cow file format, the header contains an unsigned 32-bit
timestamp, which is good until y2106, passing this through a
'long long' gives us a consistent interpretation between 32-bit
and 64-bit um kernels.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent 37e86e0f

arch/um/drivers/cow.h

+1 −1
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ extern int init_cow_file(int fd, char *cow_file, char *backing_file, 
extern int file_reader(__u64 offset, char *buf, int len, void *arg);

extern int read_cow_header(int (*reader)(__u64, char *, int, void *),

			   void *arg, __u32 *version_out,

			   char **backing_file_out, time_t *mtime_out,

			   char **backing_file_out, long long *mtime_out,

			   unsigned long long *size_out, int *sectorsize_out,

			   __u32 *align_out, int *bitmap_offset_out);

arch/um/drivers/cow_user.c

+4 −3
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 


#define PATH_LEN_V1 256



/* unsigned time_t works until year 2106 */

typedef __u32 time32_t;



struct cow_header_v1 {
@@ -197,7 +198,7 @@ int write_cow_header(char *cow_file, int fd, char *backing_file, 
		     int sectorsize, int alignment, unsigned long long *size)

{

	struct cow_header_v3 *header;

	unsigned long modtime;

	long long modtime;

	int err;



	err = cow_seek_file(fd, 0);
@@ -276,7 +277,7 @@ int file_reader(__u64 offset, char *buf, int len, void *arg) 


int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg,

		    __u32 *version_out, char **backing_file_out,

		    time_t *mtime_out, unsigned long long *size_out,

		    long long *mtime_out, unsigned long long *size_out,

		    int *sectorsize_out, __u32 *align_out,

		    int *bitmap_offset_out)

{
@@ -363,7 +364,7 @@ int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg, 


		/*

		 * this was used until Dec2005 - 64bits are needed to represent

		 * 2038+. I.e. we can safely do this truncating cast.

		 * 2106+. I.e. we can safely do this truncating cast.

		 *

		 * Additionally, we must use be32toh() instead of be64toh(), since

		 * the program used to use the former (tested - I got mtime

arch/um/drivers/ubd_kern.c

+5 −5
Original line number Diff line number Diff line
@@ -561,7 +561,7 @@ static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out) 
	__u32 version;

	__u32 align;

	char *backing_file;

	time_t mtime;

	time64_t mtime;

	unsigned long long size;

	int sector_size;

	int bitmap_offset;
@@ -600,9 +600,9 @@ static int read_cow_bitmap(int fd, void *buf, int offset, int len) 
	return 0;

}



static int backing_file_mismatch(char *file, __u64 size, time_t mtime)

static int backing_file_mismatch(char *file, __u64 size, time64_t mtime)

{

	unsigned long modtime;

	time64_t modtime;

	unsigned long long actual;

	int err;
@@ -628,7 +628,7 @@ static int backing_file_mismatch(char *file, __u64 size, time_t mtime) 
		return -EINVAL;

	}

	if (modtime != mtime) {

		printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "

		printk(KERN_ERR "mtime mismatch (%lld vs %lld) of COW header vs "

		       "backing file\n", mtime, modtime);

		return -EINVAL;

	}
@@ -671,7 +671,7 @@ static int open_ubd_file(char *file, struct openflags *openflags, int shared, 
		  unsigned long *bitmap_len_out, int *data_offset_out,

		  int *create_cow_out)

{

	time_t mtime;

	time64_t mtime;

	unsigned long long size;

	__u32 version, align;

	char *backing_file;

arch/um/include/shared/os.h

+1 −1
Original line number Diff line number Diff line
@@ -150,7 +150,7 @@ extern int os_sync_file(int fd); 
extern int os_file_size(const char *file, unsigned long long *size_out);

extern int os_pread_file(int fd, void *buf, int len, unsigned long long offset);

extern int os_pwrite_file(int fd, const void *buf, int count, unsigned long long offset);

extern int os_file_modtime(const char *file, unsigned long *modtime);

extern int os_file_modtime(const char *file, long long *modtime);

extern int os_pipe(int *fd, int stream, int close_on_exec);

extern int os_set_fd_async(int fd);

extern int os_clear_fd_async(int fd);

arch/um/os-Linux/file.c

+1 −1
Original line number Diff line number Diff line
@@ -341,7 +341,7 @@ int os_file_size(const char *file, unsigned long long *size_out) 
	return 0;

}



int os_file_modtime(const char *file, unsigned long *modtime)

int os_file_modtime(const char *file, long long *modtime)

{

	struct uml_stat buf;

	int err;

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