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authorDenys Vlasenko2021-10-08 02:16:41 +0200
committerDenys Vlasenko2021-10-08 02:20:10 +0200
commitcf4dc4a09d2a7516e00c276396da85e1088a0ddf (patch)
tree46d0b4717e89b20a470147be524472cad7ffeb4c
parentc28313bb176639e1e4b11a63f6452baebf69f28e (diff)
downloadbusybox-cf4dc4a09d2a7516e00c276396da85e1088a0ddf.zip
busybox-cf4dc4a09d2a7516e00c276396da85e1088a0ddf.tar.gz
mount: "mount -o rw ...." should not fall back to RO mount
The reported case was an attempt to remount,rw a CD-ROM: mount -o remount,rw /mnt/sr0 which "succeeded" by falling back to RO: mount("/dev/sr0", "/mnt/sr0", 0x412862, MS_REMOUNT|MS_SILENT|MS_RELATIME, "nojoliet,check=s,map=n,blocksize"...) = -1 EROFS (Read-only file system) ... mount("/dev/sr0", "/mnt/sr0", 0x412862, MS_RDONLY|MS_REMOUNT|MS_SILENT|MS_RELATIME, "nojoliet,check=s,map=n,blocksize"...) = 0 Clearly, not what was intended! function old new delta parse_mount_options 241 267 +26 mount_main 1198 1211 +13 singlemount 1301 1313 +12 inetd_main 1919 1911 -8 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 3/1 up/down: 51/-8) Total: 43 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--util-linux/mount.c21
1 files changed, 13 insertions, 8 deletions
diff --git a/util-linux/mount.c b/util-linux/mount.c
index 44afdbc..4e65b6b 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -589,7 +589,7 @@ static void append_mount_options(char **oldopts, const char *newopts)
// Use the mount_options list to parse options into flags.
// Also update list of unrecognized options if unrecognized != NULL
-static unsigned long parse_mount_options(char *options, char **unrecognized)
+static unsigned long parse_mount_options(char *options, char **unrecognized, uint32_t *opt)
{
unsigned long flags = MS_SILENT;
@@ -617,6 +617,11 @@ static unsigned long parse_mount_options(char *options, char **unrecognized)
flags &= fl;
else
flags |= fl;
+ /* If we see "-o rw" on command line, it's the same as -w:
+ * "do not try to fall back to RO mounts"
+ */
+ if (fl == ~MS_RDONLY && opt)
+ (*opt) |= OPT_w;
goto found;
}
option_str += opt_len + 1;
@@ -1973,7 +1978,7 @@ static int singlemount(struct mntent *mp, int ignore_busy)
errno = 0;
- vfsflags = parse_mount_options(mp->mnt_opts, &filteropts);
+ vfsflags = parse_mount_options(mp->mnt_opts, &filteropts, NULL);
// Treat fstype "auto" as unspecified
if (mp->mnt_type && strcmp(mp->mnt_type, "auto") == 0)
@@ -2047,7 +2052,7 @@ static int singlemount(struct mntent *mp, int ignore_busy)
len, share,
share + len + 1 /* "dir1/dir2" */
);
- parse_mount_options(unc, &filteropts);
+ parse_mount_options(unc, &filteropts, NULL);
if (ENABLE_FEATURE_CLEAN_UP) free(unc);
}
@@ -2073,7 +2078,7 @@ static int singlemount(struct mntent *mp, int ignore_busy)
// (instead of _numeric_ iface_id) with glibc.
// This probably should be fixed in glibc, not here.
// The workaround is to manually specify correct "ip=ADDR%n" option.
- parse_mount_options(ip, &filteropts);
+ parse_mount_options(ip, &filteropts, NULL);
if (ENABLE_FEATURE_CLEAN_UP) free(ip);
}
@@ -2355,7 +2360,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
// Past this point, we are handling either "mount -a [opts]"
// or "mount [opts] single_param"
- cmdopt_flags = parse_mount_options(cmdopts, NULL);
+ cmdopt_flags = parse_mount_options(cmdopts, NULL, &option_mask32);
if (nonroot && (cmdopt_flags & ~MS_SILENT)) // Non-root users cannot specify flags
bb_simple_error_msg_and_die(bb_msg_you_must_be_root);
@@ -2429,7 +2434,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
continue;
// Skip noauto and swap anyway
- if ((parse_mount_options(mtcur->mnt_opts, NULL) & (MOUNT_NOAUTO | MOUNT_SWAP))
+ if ((parse_mount_options(mtcur->mnt_opts, NULL, NULL) & (MOUNT_NOAUTO | MOUNT_SWAP))
// swap is bogus "fstype", parse_mount_options can't check fstypes
|| strcasecmp(mtcur->mnt_type, "swap") == 0
) {
@@ -2490,7 +2495,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
// exit_group(32) = ?
#if 0
// In case we want to simply skip swap partitions:
- l = parse_mount_options(mtcur->mnt_opts, NULL);
+ l = parse_mount_options(mtcur->mnt_opts, NULL, NULL);
if ((l & MOUNT_SWAP)
// swap is bogus "fstype", parse_mount_options can't check fstypes
|| strcasecmp(mtcur->mnt_type, "swap") == 0
@@ -2500,7 +2505,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
#endif
if (nonroot) {
// fstab must have "users" or "user"
- l = parse_mount_options(mtcur->mnt_opts, NULL);
+ l = parse_mount_options(mtcur->mnt_opts, NULL, NULL);
if (!(l & MOUNT_USERS))
bb_simple_error_msg_and_die(bb_msg_you_must_be_root);
}