[PATCH 06/15] mkfs: validate logarithmic parameters sanely

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

Testing logarithmic paramters like "-n log=<num>" shows that we do a
terrible job of validating such input. e.g.:

# mkfs.xfs -f -n log=456858480 /dev/vda
.....
naming   =version 2              bsize=65536  ascii-ci=0 ftype=0
....

Yeah, I just asked for a block size of 2^456858480, and it didn't
get rejected. Great, isn't it?

So, factor out the parsing of logarithmic parameters, and pass in
the maximum valid value that they can take. These maximum values
might not be completely accurate (e.g. block/sector sizes will
affect the eventual valid maximum) but we can get rid of all the
overflows and stupidities before we get to fine-grained validity
checking later in mkfs once things like block and sector sizes have
been finalised.

Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 mkfs/xfs_mkfs.c | 79 +++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 51 insertions(+), 28 deletions(-)

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 126cbea..fbb2a35 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -982,6 +982,27 @@ getbool(
 	return c ? true : false;
 }
 
+static int
+getnum_checked(
+	const char	*str,
+	long long	min_val,
+	long long	max_val,
+	const char	*illegal_str,
+	char		reqval_char,
+	char		*reqval_opts[],
+	int		reqval_optind)
+{
+	long long	c;
+
+	if (!str || *str == '\0')
+		reqval(reqval_char, reqval_opts, reqval_optind);
+
+	c = getnum(str, 0, 0, false);
+	if (c < min_val || c > max_val)
+		illegal(str, illegal_str);
+	return c;
+}
+
 int
 main(
 	int			argc,
@@ -1132,16 +1153,16 @@ main(
 
 				switch (getsubopt(&p, (constpp)bopts, &value)) {
 				case B_LOG:
-					if (!value || *value == '\0')
-						reqval('b', bopts, B_LOG);
 					if (blflag)
 						respec('b', bopts, B_LOG);
 					if (bsflag)
 						conflict('b', bopts, B_SIZE,
 							 B_LOG);
-					blocklog = getnum(value, 0, 0, false);
-					if (blocklog <= 0)
-						illegal(value, "b log");
+					blocklog = getnum_checked(value,
+							XFS_MIN_BLOCKSIZE_LOG,
+							XFS_MAX_BLOCKSIZE_LOG,
+							"b log", 'b', bopts,
+							B_LOG);
 					blocksize = 1 << blocklog;
 					blflag = 1;
 					break;
@@ -1278,16 +1299,16 @@ main(
 					nodsflag = 1;
 					break;
 				case D_SECTLOG:
-					if (!value || *value == '\0')
-						reqval('d', dopts, D_SECTLOG);
 					if (slflag)
 						respec('d', dopts, D_SECTLOG);
 					if (ssflag)
 						conflict('d', dopts, D_SECTSIZE,
 							 D_SECTLOG);
-					sectorlog = getnum(value, 0, 0, false);
-					if (sectorlog <= 0)
-						illegal(value, "d sectlog");
+					sectorlog = getnum_checked(value,
+							XFS_MIN_SECTORSIZE_LOG,
+							XFS_MAX_SECTORSIZE_LOG,
+							"d sectlog", 'd', dopts,
+							D_SECTLOG);
 					sectorsize = 1 << sectorlog;
 					slflag = 1;
 					break;
@@ -1352,9 +1373,11 @@ main(
 					if (isflag)
 						conflict('i', iopts, I_SIZE,
 							 I_LOG);
-					inodelog = getnum(value, 0, 0, false);
-					if (inodelog <= 0)
-						illegal(value, "i log");
+					inodelog = getnum_checked(value,
+							XFS_DINODE_MIN_LOG,
+							XFS_DINODE_MAX_LOG,
+							"i log", 'i', iopts,
+							I_LOG);
 					isize = 1 << inodelog;
 					ilflag = 1;
 					break;
@@ -1514,16 +1537,16 @@ main(
 					lsflag = 1;
 					break;
 				case L_SECTLOG:
-					if (!value || *value == '\0')
-						reqval('l', lopts, L_SECTLOG);
 					if (lslflag)
 						respec('l', lopts, L_SECTLOG);
 					if (lssflag)
 						conflict('l', lopts, L_SECTSIZE,
 							 L_SECTLOG);
-					lsectorlog = getnum(value, 0, 0, false);
-					if (lsectorlog <= 0)
-						illegal(value, "l sectlog");
+					lsectorlog = getnum_checked(value,
+							XFS_MIN_SECTORSIZE_LOG,
+							XFS_MAX_SECTORSIZE_LOG,
+							"l sectlog", 'l', lopts,
+							L_SECTLOG);
 					lsectorsize = 1 << lsectorlog;
 					lslflag = 1;
 					break;
@@ -1588,16 +1611,16 @@ _("cannot specify both -m crc=1 and -n ftype\n"));
 
 				switch (getsubopt(&p, (constpp)nopts, &value)) {
 				case N_LOG:
-					if (!value || *value == '\0')
-						reqval('n', nopts, N_LOG);
 					if (nlflag)
 						respec('n', nopts, N_LOG);
 					if (nsflag)
 						conflict('n', nopts, N_SIZE,
 							 N_LOG);
-					dirblocklog = getnum(value, 0, 0, false);
-					if (dirblocklog <= 0)
-						illegal(value, "n log");
+					dirblocklog = getnum_checked(value,
+							XFS_MIN_REC_DIRSIZE,
+							XFS_MAX_BLOCKSIZE_LOG,
+							"n log", 'n', nopts,
+							N_LOG);
 					dirblocksize = 1 << dirblocklog;
 					nlflag = 1;
 					break;
@@ -1716,16 +1739,16 @@ _("cannot specify both -m crc=1 and -n ftype\n"));
 				switch (getsubopt(&p, (constpp)sopts, &value)) {
 				case S_LOG:
 				case S_SECTLOG:
-					if (!value || *value == '\0')
-						reqval('s', sopts, S_SECTLOG);
 					if (slflag || lslflag)
 						respec('s', sopts, S_SECTLOG);
 					if (ssflag || lssflag)
 						conflict('s', sopts, S_SECTSIZE,
 							 S_SECTLOG);
-					sectorlog = getnum(value, 0, 0, false);
-					if (sectorlog <= 0)
-						illegal(value, "s sectlog");
+					sectorlog = getnum_checked(value,
+							XFS_MIN_SECTORSIZE_LOG,
+							XFS_MAX_SECTORSIZE_LOG,
+							"s sectlog", 's', sopts,
+							S_SECTLOG);
 					lsectorlog = sectorlog;
 					sectorsize = 1 << sectorlog;
 					lsectorsize = sectorsize;
-- 
1.8.4.rc3