diff mbox series

[RFC,v2,20/27] libselinux: check for stream rewind failures

Message ID 20230814132025.45364-21-cgzones@googlemail.com (mailing list archive)
State Accepted
Commit 9911f2ac6f77
Delegated to: Petr Lautrbach
Headers show
Series libselinux: rework selabel_file(5) database | expand

Commit Message

Christian Göttsche Aug. 14, 2023, 1:20 p.m. UTC 
Use fseek(3) instead of rewind(3) to detect failures.

Drop the final rewind in digest_add_specfile(), since all callers are
going to close the stream without any further action.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
---
 libselinux/src/is_customizable_type.c   |  7 ++++++-
 libselinux/src/label_backends_android.c |  5 ++++-
 libselinux/src/label_file.c             | 16 +++++++++++++---
 libselinux/src/label_media.c            |  5 ++++-
 libselinux/src/label_support.c          |  5 +++--
 libselinux/src/label_x.c                |  5 ++++-
 6 files changed, 34 insertions(+), 9 deletions(-)

Comments

James Carter Oct. 11, 2023, 6:48 p.m. UTC | #1 
On Mon, Aug 14, 2023 at 9:41 AM Christian Göttsche
<cgzones@googlemail.com> wrote:
>
> Use fseek(3) instead of rewind(3) to detect failures.
>
> Drop the final rewind in digest_add_specfile(), since all callers are
> going to close the stream without any further action.
>
> Signed-off-by: Christian Göttsche <cgzones@googlemail.com>

Acked-by: James Carter <jwcart2@gmail.com>

> ---
>  libselinux/src/is_customizable_type.c   |  7 ++++++-
>  libselinux/src/label_backends_android.c |  5 ++++-
>  libselinux/src/label_file.c             | 16 +++++++++++++---
>  libselinux/src/label_media.c            |  5 ++++-
>  libselinux/src/label_support.c          |  5 +++--
>  libselinux/src/label_x.c                |  5 ++++-
>  6 files changed, 34 insertions(+), 9 deletions(-)
>
> diff --git a/libselinux/src/is_customizable_type.c b/libselinux/src/is_customizable_type.c
> index f83e1e83..9be50174 100644
> --- a/libselinux/src/is_customizable_type.c
> +++ b/libselinux/src/is_customizable_type.c
> @@ -31,7 +31,12 @@ static void customizable_init(void)
>         while (fgets_unlocked(buf, selinux_page_size, fp) && ctr < UINT_MAX) {
>                 ctr++;
>         }
> -       rewind(fp);
> +
> +       if (fseek(fp, 0L, SEEK_SET) == -1) {
> +               fclose(fp);
> +               return;
> +       }
> +
>         if (ctr) {
>                 list =
>                     (char **) calloc(sizeof(char *),
> diff --git a/libselinux/src/label_backends_android.c b/libselinux/src/label_backends_android.c
> index c2d78360..6494f3cd 100644
> --- a/libselinux/src/label_backends_android.c
> +++ b/libselinux/src/label_backends_android.c
> @@ -208,7 +208,10 @@ static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
>                                 goto finish;
>
>                         maxnspec = data->nspec;
> -                       rewind(fp);
> +
> +                       status = fseek(fp, 0L, SEEK_SET);
> +                       if (status == -1)
> +                               goto finish;
>                 }
>         }
>
> diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c
> index 471fd56b..a5677411 100644
> --- a/libselinux/src/label_file.c
> +++ b/libselinux/src/label_file.c
> @@ -519,12 +519,16 @@ static char *rolling_append(char *current, const char *suffix, size_t max)
>         return current;
>  }
>
> -static bool fcontext_is_binary(FILE *fp)
> +static int fcontext_is_binary(FILE *fp)
>  {
>         uint32_t magic;
> +       int rc;
>
>         size_t len = fread(&magic, sizeof(magic), 1, fp);
> -       rewind(fp);
> +
> +       rc = fseek(fp, 0L, SEEK_SET);
> +       if (rc == -1)
> +               return -1;
>
>         return (len && (magic == SELINUX_MAGIC_COMPILED_FCONTEXT));
>  }
> @@ -622,7 +626,13 @@ static int process_file(const char *path, const char *suffix,
>                 if (fp == NULL)
>                         return -1;
>
> -               rc = fcontext_is_binary(fp) ?
> +               rc = fcontext_is_binary(fp);
> +               if (rc < 0) {
> +                       (void) fclose(fp);
> +                       return -1;
> +               }
> +
> +               rc = rc ?
>                                 load_mmap(fp, sb.st_size, rec, found_path) :
>                                 process_text_file(fp, rec, found_path);
>                 if (!rc)
> diff --git a/libselinux/src/label_media.c b/libselinux/src/label_media.c
> index f09461ab..b3443b47 100644
> --- a/libselinux/src/label_media.c
> +++ b/libselinux/src/label_media.c
> @@ -130,7 +130,10 @@ static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
>                                 goto finish;
>                         memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
>                         maxnspec = data->nspec;
> -                       rewind(fp);
> +
> +                       status = fseek(fp, 0L, SEEK_SET);
> +                       if (status == -1)
> +                               goto finish;
>                 }
>         }
>         free(line_buf);
> diff --git a/libselinux/src/label_support.c b/libselinux/src/label_support.c
> index 94fb6697..f7ab9292 100644
> --- a/libselinux/src/label_support.c
> +++ b/libselinux/src/label_support.c
> @@ -174,12 +174,13 @@ int  digest_add_specfile(struct selabel_digest *digest, FILE *fp,
>         digest->hashbuf = tmp_buf;
>
>         if (fp) {
> -               rewind(fp);
> +               if (fseek(fp, 0L, SEEK_SET) == -1)
> +                       return -1;
> +
>                 if (fread(digest->hashbuf + (digest->hashbuf_size - buf_len),
>                                             1, buf_len, fp) != buf_len)
>                         return -1;
>
> -               rewind(fp);
>         } else if (from_addr) {
>                 tmp_buf = memcpy(digest->hashbuf +
>                                     (digest->hashbuf_size - buf_len),
> diff --git a/libselinux/src/label_x.c b/libselinux/src/label_x.c
> index e80bf107..e15190ca 100644
> --- a/libselinux/src/label_x.c
> +++ b/libselinux/src/label_x.c
> @@ -157,7 +157,10 @@ static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
>                                 goto finish;
>                         memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
>                         maxnspec = data->nspec;
> -                       rewind(fp);
> +
> +                       status = fseek(fp, 0L, SEEK_SET);
> +                       if (status == -1)
> +                               goto finish;
>                 }
>         }
>         free(line_buf);
> --
> 2.40.1
>
James Carter Oct. 12, 2023, 5:56 p.m. UTC | #2 
On Wed, Oct 11, 2023 at 2:48 PM James Carter <jwcart2@gmail.com> wrote:
>
> On Mon, Aug 14, 2023 at 9:41 AM Christian Göttsche
> <cgzones@googlemail.com> wrote:
> >
> > Use fseek(3) instead of rewind(3) to detect failures.
> >
> > Drop the final rewind in digest_add_specfile(), since all callers are
> > going to close the stream without any further action.
> >
> > Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
>
> Acked-by: James Carter <jwcart2@gmail.com>
>
Merged.
Thanks,
Jim

> > ---
> >  libselinux/src/is_customizable_type.c   |  7 ++++++-
> >  libselinux/src/label_backends_android.c |  5 ++++-
> >  libselinux/src/label_file.c             | 16 +++++++++++++---
> >  libselinux/src/label_media.c            |  5 ++++-
> >  libselinux/src/label_support.c          |  5 +++--
> >  libselinux/src/label_x.c                |  5 ++++-
> >  6 files changed, 34 insertions(+), 9 deletions(-)
> >
> > diff --git a/libselinux/src/is_customizable_type.c b/libselinux/src/is_customizable_type.c
> > index f83e1e83..9be50174 100644
> > --- a/libselinux/src/is_customizable_type.c
> > +++ b/libselinux/src/is_customizable_type.c
> > @@ -31,7 +31,12 @@ static void customizable_init(void)
> >         while (fgets_unlocked(buf, selinux_page_size, fp) && ctr < UINT_MAX) {
> >                 ctr++;
> >         }
> > -       rewind(fp);
> > +
> > +       if (fseek(fp, 0L, SEEK_SET) == -1) {
> > +               fclose(fp);
> > +               return;
> > +       }
> > +
> >         if (ctr) {
> >                 list =
> >                     (char **) calloc(sizeof(char *),
> > diff --git a/libselinux/src/label_backends_android.c b/libselinux/src/label_backends_android.c
> > index c2d78360..6494f3cd 100644
> > --- a/libselinux/src/label_backends_android.c
> > +++ b/libselinux/src/label_backends_android.c
> > @@ -208,7 +208,10 @@ static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
> >                                 goto finish;
> >
> >                         maxnspec = data->nspec;
> > -                       rewind(fp);
> > +
> > +                       status = fseek(fp, 0L, SEEK_SET);
> > +                       if (status == -1)
> > +                               goto finish;
> >                 }
> >         }
> >
> > diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c
> > index 471fd56b..a5677411 100644
> > --- a/libselinux/src/label_file.c
> > +++ b/libselinux/src/label_file.c
> > @@ -519,12 +519,16 @@ static char *rolling_append(char *current, const char *suffix, size_t max)
> >         return current;
> >  }
> >
> > -static bool fcontext_is_binary(FILE *fp)
> > +static int fcontext_is_binary(FILE *fp)
> >  {
> >         uint32_t magic;
> > +       int rc;
> >
> >         size_t len = fread(&magic, sizeof(magic), 1, fp);
> > -       rewind(fp);
> > +
> > +       rc = fseek(fp, 0L, SEEK_SET);
> > +       if (rc == -1)
> > +               return -1;
> >
> >         return (len && (magic == SELINUX_MAGIC_COMPILED_FCONTEXT));
> >  }
> > @@ -622,7 +626,13 @@ static int process_file(const char *path, const char *suffix,
> >                 if (fp == NULL)
> >                         return -1;
> >
> > -               rc = fcontext_is_binary(fp) ?
> > +               rc = fcontext_is_binary(fp);
> > +               if (rc < 0) {
> > +                       (void) fclose(fp);
> > +                       return -1;
> > +               }
> > +
> > +               rc = rc ?
> >                                 load_mmap(fp, sb.st_size, rec, found_path) :
> >                                 process_text_file(fp, rec, found_path);
> >                 if (!rc)
> > diff --git a/libselinux/src/label_media.c b/libselinux/src/label_media.c
> > index f09461ab..b3443b47 100644
> > --- a/libselinux/src/label_media.c
> > +++ b/libselinux/src/label_media.c
> > @@ -130,7 +130,10 @@ static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
> >                                 goto finish;
> >                         memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
> >                         maxnspec = data->nspec;
> > -                       rewind(fp);
> > +
> > +                       status = fseek(fp, 0L, SEEK_SET);
> > +                       if (status == -1)
> > +                               goto finish;
> >                 }
> >         }
> >         free(line_buf);
> > diff --git a/libselinux/src/label_support.c b/libselinux/src/label_support.c
> > index 94fb6697..f7ab9292 100644
> > --- a/libselinux/src/label_support.c
> > +++ b/libselinux/src/label_support.c
> > @@ -174,12 +174,13 @@ int  digest_add_specfile(struct selabel_digest *digest, FILE *fp,
> >         digest->hashbuf = tmp_buf;
> >
> >         if (fp) {
> > -               rewind(fp);
> > +               if (fseek(fp, 0L, SEEK_SET) == -1)
> > +                       return -1;
> > +
> >                 if (fread(digest->hashbuf + (digest->hashbuf_size - buf_len),
> >                                             1, buf_len, fp) != buf_len)
> >                         return -1;
> >
> > -               rewind(fp);
> >         } else if (from_addr) {
> >                 tmp_buf = memcpy(digest->hashbuf +
> >                                     (digest->hashbuf_size - buf_len),
> > diff --git a/libselinux/src/label_x.c b/libselinux/src/label_x.c
> > index e80bf107..e15190ca 100644
> > --- a/libselinux/src/label_x.c
> > +++ b/libselinux/src/label_x.c
> > @@ -157,7 +157,10 @@ static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
> >                                 goto finish;
> >                         memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
> >                         maxnspec = data->nspec;
> > -                       rewind(fp);
> > +
> > +                       status = fseek(fp, 0L, SEEK_SET);
> > +                       if (status == -1)
> > +                               goto finish;
> >                 }
> >         }
> >         free(line_buf);
> > --
> > 2.40.1
> >
diff mbox series

Patch

diff --git a/libselinux/src/is_customizable_type.c b/libselinux/src/is_customizable_type.c
index f83e1e83..9be50174 100644
--- a/libselinux/src/is_customizable_type.c
+++ b/libselinux/src/is_customizable_type.c
@@ -31,7 +31,12 @@  static void customizable_init(void)
 	while (fgets_unlocked(buf, selinux_page_size, fp) && ctr < UINT_MAX) {
 		ctr++;
 	}
-	rewind(fp);
+
+	if (fseek(fp, 0L, SEEK_SET) == -1) {
+		fclose(fp);
+		return;
+	}
+
 	if (ctr) {
 		list =
 		    (char **) calloc(sizeof(char *),
diff --git a/libselinux/src/label_backends_android.c b/libselinux/src/label_backends_android.c
index c2d78360..6494f3cd 100644
--- a/libselinux/src/label_backends_android.c
+++ b/libselinux/src/label_backends_android.c
@@ -208,7 +208,10 @@  static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
 				goto finish;
 
 			maxnspec = data->nspec;
-			rewind(fp);
+
+			status = fseek(fp, 0L, SEEK_SET);
+			if (status == -1)
+				goto finish;
 		}
 	}
 
diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c
index 471fd56b..a5677411 100644
--- a/libselinux/src/label_file.c
+++ b/libselinux/src/label_file.c
@@ -519,12 +519,16 @@  static char *rolling_append(char *current, const char *suffix, size_t max)
 	return current;
 }
 
-static bool fcontext_is_binary(FILE *fp)
+static int fcontext_is_binary(FILE *fp)
 {
 	uint32_t magic;
+	int rc;
 
 	size_t len = fread(&magic, sizeof(magic), 1, fp);
-	rewind(fp);
+
+	rc = fseek(fp, 0L, SEEK_SET);
+	if (rc == -1)
+		return -1;
 
 	return (len && (magic == SELINUX_MAGIC_COMPILED_FCONTEXT));
 }
@@ -622,7 +626,13 @@  static int process_file(const char *path, const char *suffix,
 		if (fp == NULL)
 			return -1;
 
-		rc = fcontext_is_binary(fp) ?
+		rc = fcontext_is_binary(fp);
+		if (rc < 0) {
+			(void) fclose(fp);
+			return -1;
+		}
+
+		rc = rc ?
 				load_mmap(fp, sb.st_size, rec, found_path) :
 				process_text_file(fp, rec, found_path);
 		if (!rc)
diff --git a/libselinux/src/label_media.c b/libselinux/src/label_media.c
index f09461ab..b3443b47 100644
--- a/libselinux/src/label_media.c
+++ b/libselinux/src/label_media.c
@@ -130,7 +130,10 @@  static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
 				goto finish;
 			memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
 			maxnspec = data->nspec;
-			rewind(fp);
+
+			status = fseek(fp, 0L, SEEK_SET);
+			if (status == -1)
+				goto finish;
 		}
 	}
 	free(line_buf);
diff --git a/libselinux/src/label_support.c b/libselinux/src/label_support.c
index 94fb6697..f7ab9292 100644
--- a/libselinux/src/label_support.c
+++ b/libselinux/src/label_support.c
@@ -174,12 +174,13 @@  int  digest_add_specfile(struct selabel_digest *digest, FILE *fp,
 	digest->hashbuf = tmp_buf;
 
 	if (fp) {
-		rewind(fp);
+		if (fseek(fp, 0L, SEEK_SET) == -1)
+			return -1;
+
 		if (fread(digest->hashbuf + (digest->hashbuf_size - buf_len),
 					    1, buf_len, fp) != buf_len)
 			return -1;
 
-		rewind(fp);
 	} else if (from_addr) {
 		tmp_buf = memcpy(digest->hashbuf +
 				    (digest->hashbuf_size - buf_len),
diff --git a/libselinux/src/label_x.c b/libselinux/src/label_x.c
index e80bf107..e15190ca 100644
--- a/libselinux/src/label_x.c
+++ b/libselinux/src/label_x.c
@@ -157,7 +157,10 @@  static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
 				goto finish;
 			memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
 			maxnspec = data->nspec;
-			rewind(fp);
+
+			status = fseek(fp, 0L, SEEK_SET);
+			if (status == -1)
+				goto finish;
 		}
 	}
 	free(line_buf);