[PATCH nft 2/2] libnftables: skip useable checks for /dev/stdin

[PATCH nft 2/2] libnftables: skip useable checks for /dev/stdin

[Pablo Neira Ayuso]

/dev/stdin is a placeholder, read() from STDIN_FILENO is used to fetch
the standard input into a buffer.

Since 5c2b2b0a2ba7 ("src: error reporting with -f and read from stdin")
stdin is stored in a buffer to fix error reporting.

Fixes: 149b1c95d129 ("libnftables: refuse to open onput files other than named pipes or regular files")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/libnftables.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/libnftables.c b/src/libnftables.c
index af4734c05004..4676b30a04b1 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -664,6 +664,7 @@ retry:
 
 /* need to use stat() to, fopen() will block for named fifos and
  * libjansson makes no checks before or after open either.
+ * /dev/stdin is *never* used, read() from STDIN_FILENO is used instead.
  */
 static struct error_record *filename_is_useable(struct nft_ctx *nft, const char *name)
 {
@@ -671,6 +672,9 @@ static struct error_record *filename_is_useable(struct nft_ctx *nft, const char
 	struct stat sb;
 	int err;
 
+	if (!strcmp(name, "/dev/stdin"))
+		return NULL;
+
 	err = stat(name, &sb);
 	if (err)
 		return error(&internal_location, "Could not open file \"%s\": %s\n",
@@ -681,9 +685,6 @@ static struct error_record *filename_is_useable(struct nft_ctx *nft, const char
 	if (type == S_IFREG || type == S_IFIFO)
 		return NULL;
 
-	if (type == S_IFCHR && 0 == strcmp(name, "/dev/stdin"))
-		return NULL;
-
 	return error(&internal_location, "Not a regular file: \"%s\"\n", name);
 }
 
-- 
2.30.2

[PATCH nft 1/2] parser_json: use stdin buffer if available

[Pablo Neira Ayuso]

Since 5c2b2b0a2ba7 ("src: error reporting with -f and read from stdin")
stdin is stored in a buffer, update json support to use it instead of
reading from /dev/stdin.

Some systems do not provide /dev/stdin symlink to /proc/self/fd/0
according to reporter (that mentions Yocto Linux as example).

Fixes: 935f82e7dd49 ("Support 'nft -f -' to read from stdin")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
v2: remove check for nft_output_json() in nft_run_cmd_from_filename()
    as suggested by Phil Sutter, so JSON support does not really use
    /dev/stdin.

 src/libnftables.c | 3 +--
 src/parser_json.c | 7 +++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/libnftables.c b/src/libnftables.c
index af4734c05004..89317f9f6049 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -807,8 +807,7 @@ int nft_run_cmd_from_filename(struct nft_ctx *nft, const char *filename)
 	if (!strcmp(filename, "-"))
 		filename = "/dev/stdin";
 
-	if (!strcmp(filename, "/dev/stdin") &&
-	    !nft_output_json(&nft->output))
+	if (!strcmp(filename, "/dev/stdin"))
 		nft->stdin_buf = stdin_to_buffer();
 
 	if (!nft->stdin_buf &&
diff --git a/src/parser_json.c b/src/parser_json.c
index ee4657ee8044..4912d3608b2b 100644
--- a/src/parser_json.c
+++ b/src/parser_json.c
@@ -4357,6 +4357,13 @@ int nft_parse_json_filename(struct nft_ctx *nft, const char *filename,
 	json_error_t err;
 	int ret;
 
+	if (nft->stdin_buf) {
+		json_indesc.type = INDESC_STDIN;
+		json_indesc.name = "/dev/stdin";
+
+		return nft_parse_json_buffer(nft, nft->stdin_buf, msgs, cmds);
+	}
+
 	json_indesc.type = INDESC_FILE;
 	json_indesc.name = filename;
 
-- 
2.30.2

[PATCH nft 2/2] libnftables: skip useable checks for /dev/stdin

[Pablo Neira Ayuso]

/dev/stdin is a placeholder, read() from STDIN_FILENO is used to fetch
the standard input into a buffer.

Since 5c2b2b0a2ba7 ("src: error reporting with -f and read from stdin")
stdin is stored in a buffer to fix error reporting.

This patch requires: ("parser_json: use stdin buffer if available")

Fixes: 149b1c95d129 ("libnftables: refuse to open onput files other than named pipes or regular files")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
v2: no changes.

 src/libnftables.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/libnftables.c b/src/libnftables.c
index 89317f9f6049..36d6a854ff50 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -664,6 +664,7 @@ retry:
 
 /* need to use stat() to, fopen() will block for named fifos and
  * libjansson makes no checks before or after open either.
+ * /dev/stdin is *never* used, read() from STDIN_FILENO is used instead.
  */
 static struct error_record *filename_is_useable(struct nft_ctx *nft, const char *name)
 {
@@ -671,6 +672,9 @@ static struct error_record *filename_is_useable(struct nft_ctx *nft, const char
 	struct stat sb;
 	int err;
 
+	if (!strcmp(name, "/dev/stdin"))
+		return NULL;
+
 	err = stat(name, &sb);
 	if (err)
 		return error(&internal_location, "Could not open file \"%s\": %s\n",
@@ -681,9 +685,6 @@ static struct error_record *filename_is_useable(struct nft_ctx *nft, const char
 	if (type == S_IFREG || type == S_IFIFO)
 		return NULL;
 
-	if (type == S_IFCHR && 0 == strcmp(name, "/dev/stdin"))
-		return NULL;
-
 	return error(&internal_location, "Not a regular file: \"%s\"\n", name);
 }
 
-- 
2.30.2

Re: [PATCH nft 1/2] parser_json: use stdin buffer if available

[Phil Sutter]

On Wed, Jul 10, 2024 at 05:20:03PM +0200, Pablo Neira Ayuso wrote:
> Since 5c2b2b0a2ba7 ("src: error reporting with -f and read from stdin")
> stdin is stored in a buffer, update json support to use it instead of
> reading from /dev/stdin.
> 
> Some systems do not provide /dev/stdin symlink to /proc/self/fd/0
> according to reporter (that mentions Yocto Linux as example).
> 
> Fixes: 935f82e7dd49 ("Support 'nft -f -' to read from stdin")
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
> v2: remove check for nft_output_json() in nft_run_cmd_from_filename()
>     as suggested by Phil Sutter, so JSON support does not really use
>     /dev/stdin.

Series:
Acked-by: Phil Sutter <phil@nwl.cc>

Thanks, Phil

Re: [PATCH nft 1/2] parser_json: use stdin buffer if available

[Pablo Neira Ayuso]

On Wed, Jul 10, 2024 at 05:52:21PM +0200, Phil Sutter wrote:
> On Wed, Jul 10, 2024 at 05:20:03PM +0200, Pablo Neira Ayuso wrote:
> > Since 5c2b2b0a2ba7 ("src: error reporting with -f and read from stdin")
> > stdin is stored in a buffer, update json support to use it instead of
> > reading from /dev/stdin.
> > 
> > Some systems do not provide /dev/stdin symlink to /proc/self/fd/0
> > according to reporter (that mentions Yocto Linux as example).
> > 
> > Fixes: 935f82e7dd49 ("Support 'nft -f -' to read from stdin")
> > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > ---
> > v2: remove check for nft_output_json() in nft_run_cmd_from_filename()
> >     as suggested by Phil Sutter, so JSON support does not really use
> >     /dev/stdin.
> 
> Series:
> Acked-by: Phil Sutter <phil@nwl.cc>

Pushed out, thanks