[PATCH v4 21/26] NFS: Add a small buffer in nfs_fs_context to avoid string dup

Scott Mayhew
2019-09-13T12:18:55Z

From: David Howells <dhowells@redhat.com>

Add a small buffer in nfs_fs_context to avoid string duplication when
parsing numbers. Also make the parsing function wrapper place the parsed
integer directly in the appropriate nfs_fs_context struct member.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/nfs/fs_context.c | 98 +++++++++++++++++++++------------------------
fs/nfs/internal.h | 2 +
2 files changed, 48 insertions(+), 52 deletions(-)

diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
index e2b584354731..ad502b37a3f3 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -468,27 +468,38 @@ static int nfs_get_option_str(substring_t args[], char **option)
return !*option;
}

-static int nfs_get_option_ul(substring_t args[], unsigned long *option)
+static int nfs_get_option_ui(struct nfs_fs_context *ctx,
+ substring_t args[], unsigned int *option)
{
- int rc;
- char *string;
+ match_strlcpy(ctx->buf, args, sizeof(ctx->buf));
+ return kstrtouint(ctx->buf, 10, option);
+}

- string = match_strdup(args);
- if (string == NULL)
- return -ENOMEM;
- rc = kstrtoul(string, 10, option);
- kfree(string);
+static int nfs_get_option_ui_bound(struct nfs_fs_context *ctx,
+ substring_t args[], unsigned int *option,
+ unsigned int l_bound, unsigned u_bound)
+{
+ int ret;

- return rc;
+ match_strlcpy(ctx->buf, args, sizeof(ctx->buf));
+ ret = kstrtouint(ctx->buf, 10, option);
+ if (ret < 0)
+ return ret;
+ if (*option < l_bound || *option > u_bound)
+ return -ERANGE;
+ return 0;
}

-static int nfs_get_option_ul_bound(substring_t args[], unsigned long *option,
- unsigned long l_bound, unsigned long u_bound)
+static int nfs_get_option_us_bound(struct nfs_fs_context *ctx,
+ substring_t args[], unsigned short *option,
+ unsigned short l_bound,
+ unsigned short u_bound)
{
int ret;

- ret = nfs_get_option_ul(args, option);
- if (ret != 0)
+ match_strlcpy(ctx->buf, args, sizeof(ctx->buf));
+ ret = kstrtou16(ctx->buf, 10, option);
+ if (ret < 0)
return ret;
if (*option < l_bound || *option > u_bound)
return -ERANGE;
@@ -501,7 +512,6 @@ static int nfs_get_option_ul_bound(substring_t args[], unsigned long *option,
static int nfs_fs_context_parse_option(struct nfs_fs_context *ctx, char *p)
{
substring_t args[MAX_OPT_ARGS];
- unsigned long option;
char *string;
int token, rc;

@@ -609,86 +619,70 @@ static int nfs_fs_context_parse_option(struct nfs_fs_context *ctx, char *p)
* options that take numeric values
*/
case Opt_port:
- if (nfs_get_option_ul(args, &option) ||
- option > USHRT_MAX)
+ if (nfs_get_option_ui_bound(ctx, args, &ctx->nfs_server.port,
+ 0, USHRT_MAX))
goto out_invalid_value;
- ctx->nfs_server.port = option;
break;
case Opt_rsize:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->rsize))
goto out_invalid_value;
- ctx->rsize = option;
break;
case Opt_wsize:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->wsize))
goto out_invalid_value;
- ctx->wsize = option;
break;
case Opt_bsize:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->bsize))
goto out_invalid_value;
- ctx->bsize = option;
break;
case Opt_timeo:
- if (nfs_get_option_ul_bound(args, &option, 1, INT_MAX))
+ if (nfs_get_option_ui_bound(ctx, args, &ctx->timeo, 1, INT_MAX))
goto out_invalid_value;
- ctx->timeo = option;
break;
case Opt_retrans:
- if (nfs_get_option_ul_bound(args, &option, 0, INT_MAX))
+ if (nfs_get_option_ui_bound(ctx, args, &ctx->retrans, 0, INT_MAX))
goto out_invalid_value;
- ctx->retrans = option;
break;
case Opt_acregmin:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->acregmin))
goto out_invalid_value;
- ctx->acregmin = option;
break;
case Opt_acregmax:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->acregmax))
goto out_invalid_value;
- ctx->acregmax = option;
break;
case Opt_acdirmin:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->acdirmin))
goto out_invalid_value;
- ctx->acdirmin = option;
break;
case Opt_acdirmax:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->acdirmax))
goto out_invalid_value;
- ctx->acdirmax = option;
break;
case Opt_actimeo:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->acdirmax))
goto out_invalid_value;
ctx->acregmin = ctx->acregmax =
- ctx->acdirmin = ctx->acdirmax = option;
+ ctx->acdirmin = ctx->acdirmax;
break;
case Opt_namelen:
- if (nfs_get_option_ul(args, &option))
+ if (nfs_get_option_ui(ctx, args, &ctx->namlen))
goto out_invalid_value;
- ctx->namlen = option;
break;
case Opt_mountport:
- if (nfs_get_option_ul(args, &option) ||
- option > USHRT_MAX)
+ if (nfs_get_option_ui_bound(ctx, args, &ctx->mount_server.port,
+ 0, USHRT_MAX))
goto out_invalid_value;
- ctx->mount_server.port = option;
break;
case Opt_mountvers:
- if (nfs_get_option_ul(args, &option) ||
- option < NFS_MNT_VERSION ||
- option > NFS_MNT3_VERSION)
+ if (nfs_get_option_ui_bound(ctx, args, &ctx->mount_server.version,
+ NFS_MNT_VERSION, NFS_MNT3_VERSION))
goto out_invalid_value;
- ctx->mount_server.version = option;
break;
case Opt_minorversion:
- if (nfs_get_option_ul(args, &option))
- goto out_invalid_value;
- if (option > NFS4_MAX_MINOR_VERSION)
+ if (nfs_get_option_ui_bound(ctx, args, &ctx->minorversion,
+ 0, NFS4_MAX_MINOR_VERSION))
goto out_invalid_value;
- ctx->minorversion = option;
break;

/*
@@ -820,9 +814,9 @@ static int nfs_fs_context_parse_option(struct nfs_fs_context *ctx, char *p)
goto out_invalid_address;
break;
case Opt_nconnect:
- if (nfs_get_option_ul_bound(args, &option, 1, NFS_MAX_CONNECTIONS))
+ if (nfs_get_option_us_bound(ctx, args, &ctx->nfs_server.nconnect,
+ 1, NFS_MAX_CONNECTIONS))
goto out_invalid_value;
- ctx->nfs_server.nconnect = option;
break;
case Opt_lookupcache:
string = match_strdup(args);
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index d084182f8e43..11df0d1f9fd4 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -130,6 +130,8 @@ struct nfs_fs_context {

void *lsm_opts;
struct net *net;
+
+ char buf[32]; /* Parse buffer */
};

/* mount_clnt.c */
--
2.17.2