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Message-ID: <CAJqdLrqCkkA=TcEU0Oo5w=6Xrp=y1VepGZncBC4yKRU1hv2iDg@mail.gmail.com>
Date: Fri, 9 May 2025 17:46:21 +0200
From: Alexander Mikhalitsyn <alexander@...alicyn.com>
To: Christian Brauner <brauner@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, Jann Horn <jannh@...gle.com>, 
	Daniel Borkmann <daniel@...earbox.net>, Kuniyuki Iwashima <kuniyu@...zon.com>, 
	Eric Dumazet <edumazet@...gle.com>, Oleg Nesterov <oleg@...hat.com>, 
	"David S. Miller" <davem@...emloft.net>, Alexander Viro <viro@...iv.linux.org.uk>, 
	Daan De Meyer <daan.j.demeyer@...il.com>, David Rheinsberg <david@...dahead.eu>, 
	Jakub Kicinski <kuba@...nel.org>, Jan Kara <jack@...e.cz>, 
	Lennart Poettering <lennart@...ttering.net>, Luca Boccassi <bluca@...ian.org>, Mike Yuan <me@...dnzj.com>, 
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Zbigniew Jędrzejewski-Szmek <zbyszek@...waw.pl>, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH v5 1/9] coredump: massage format_corname()

Hi Christian!

Am Fr., 9. Mai 2025 um 12:25 Uhr schrieb Christian Brauner <brauner@...nel.org>:
>
> We're going to extend the coredump code in follow-up patches.
> Clean it up so we can do this more easily.
>
> Signed-off-by: Christian Brauner <brauner@...nel.org>
> ---
>  fs/coredump.c | 41 ++++++++++++++++++++++++-----------------
>  1 file changed, 24 insertions(+), 17 deletions(-)
>
> diff --git a/fs/coredump.c b/fs/coredump.c
> index d740a0411266..281320ea351f 100644
> --- a/fs/coredump.c
> +++ b/fs/coredump.c
> @@ -76,9 +76,15 @@ static char core_pattern[CORENAME_MAX_SIZE] = "core";
>  static int core_name_size = CORENAME_MAX_SIZE;
>  unsigned int core_file_note_size_limit = CORE_FILE_NOTE_SIZE_DEFAULT;
>
> +enum coredump_type_t {
> +       COREDUMP_FILE = 1,
> +       COREDUMP_PIPE = 2,
> +};
> +
>  struct core_name {
>         char *corename;
>         int used, size;
> +       enum coredump_type_t core_type;
>  };
>
>  static int expand_corename(struct core_name *cn, int size)
> @@ -218,18 +224,21 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm,
>  {
>         const struct cred *cred = current_cred();
>         const char *pat_ptr = core_pattern;
> -       int ispipe = (*pat_ptr == '|');
>         bool was_space = false;
>         int pid_in_pattern = 0;
>         int err = 0;
>
>         cn->used = 0;
>         cn->corename = NULL;
> +       if (*pat_ptr == '|')
> +               cn->core_type = COREDUMP_PIPE;
> +       else
> +               cn->core_type = COREDUMP_FILE;
>         if (expand_corename(cn, core_name_size))
>                 return -ENOMEM;
>         cn->corename[0] = '\0';
>
> -       if (ispipe) {
> +       if (cn->core_type == COREDUMP_PIPE) {
>                 int argvs = sizeof(core_pattern) / 2;
>                 (*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL);
>                 if (!(*argv))
> @@ -247,7 +256,7 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm,
>                  * Split on spaces before doing template expansion so that
>                  * %e and %E don't get split if they have spaces in them
>                  */
> -               if (ispipe) {
> +               if (cn->core_type == COREDUMP_PIPE) {
>                         if (isspace(*pat_ptr)) {
>                                 if (cn->used != 0)
>                                         was_space = true;
> @@ -353,7 +362,7 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm,
>                                  * Installing a pidfd only makes sense if
>                                  * we actually spawn a usermode helper.
>                                  */
> -                               if (!ispipe)
> +                               if (!(cn->core_type != COREDUMP_PIPE))

Shouldn't it be:
if (cn->core_type != COREDUMP_PIPE)

Except this, LGTM

Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>

>                                         break;
>
>                                 /*
> @@ -384,12 +393,12 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm,
>          * If core_pattern does not include a %p (as is the default)
>          * and core_uses_pid is set, then .%pid will be appended to
>          * the filename. Do not do this for piped commands. */
> -       if (!ispipe && !pid_in_pattern && core_uses_pid) {
> +       if (!(cn->core_type == COREDUMP_PIPE) && !pid_in_pattern && core_uses_pid) {
>                 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
>                 if (err)
>                         return err;
>         }
> -       return ispipe;
> +       return 0;
>  }
>
>  static int zap_process(struct signal_struct *signal, int exit_code)
> @@ -583,7 +592,6 @@ void do_coredump(const kernel_siginfo_t *siginfo)
>         const struct cred *old_cred;
>         struct cred *cred;
>         int retval = 0;
> -       int ispipe;
>         size_t *argv = NULL;
>         int argc = 0;
>         /* require nonrelative corefile path and be extra careful */
> @@ -632,19 +640,18 @@ void do_coredump(const kernel_siginfo_t *siginfo)
>
>         old_cred = override_creds(cred);
>
> -       ispipe = format_corename(&cn, &cprm, &argv, &argc);
> +       retval = format_corename(&cn, &cprm, &argv, &argc);
> +       if (retval < 0) {
> +               coredump_report_failure("format_corename failed, aborting core");
> +               goto fail_unlock;
> +       }
>
> -       if (ispipe) {
> +       if (cn.core_type == COREDUMP_PIPE) {
>                 int argi;
>                 int dump_count;
>                 char **helper_argv;
>                 struct subprocess_info *sub_info;
>
> -               if (ispipe < 0) {
> -                       coredump_report_failure("format_corename failed, aborting core");
> -                       goto fail_unlock;
> -               }
> -
>                 if (cprm.limit == 1) {
>                         /* See umh_coredump_setup() which sets RLIMIT_CORE = 1.
>                          *
> @@ -695,7 +702,7 @@ void do_coredump(const kernel_siginfo_t *siginfo)
>                         coredump_report_failure("|%s pipe failed", cn.corename);
>                         goto close_fail;
>                 }
> -       } else {
> +       } else if (cn.core_type == COREDUMP_FILE) {
>                 struct mnt_idmap *idmap;
>                 struct inode *inode;
>                 int open_flags = O_CREAT | O_WRONLY | O_NOFOLLOW |
> @@ -823,13 +830,13 @@ void do_coredump(const kernel_siginfo_t *siginfo)
>                 file_end_write(cprm.file);
>                 free_vma_snapshot(&cprm);
>         }
> -       if (ispipe && core_pipe_limit)
> +       if ((cn.core_type == COREDUMP_PIPE) && core_pipe_limit)
>                 wait_for_dump_helpers(cprm.file);
>  close_fail:
>         if (cprm.file)
>                 filp_close(cprm.file, NULL);
>  fail_dropcount:
> -       if (ispipe)
> +       if (cn.core_type == COREDUMP_PIPE)
>                 atomic_dec(&core_dump_count);
>  fail_unlock:
>         kfree(argv);
>
> --
> 2.47.2
>

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