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dl: Add support for persistent modules

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This type of modules cannot be unloaded. This is useful if a given
functionality, e.g. UEFI secure boot shim signature verification, should
not be disabled if it was enabled at some point in time. Somebody may
say that we can use standalone GRUB2 here. That is true. However, the
code is not so big nor complicated hence it make sense to support
modularized configs too.

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>
This commit is contained in:
Daniel Kiper 2018-10-02 18:49:26 +02:00 committed by Vincent Batts
parent 29e76e7402
commit 1cb4edf4ef
2 changed files with 16 additions and 0 deletions
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3
grub-core/commands/minicmd.c
View file

@ -137,6 +137,9 @@ grub_mini_cmd_rmmod (struct grub_command *cmd __attribute__ ((unused)),
if (! mod) if (! mod)
return grub_error (GRUB_ERR_BAD_ARGUMENT, "no such module"); return grub_error (GRUB_ERR_BAD_ARGUMENT, "no such module");
if (grub_dl_is_persistent (mod))
return grub_error (GRUB_ERR_BAD_ARGUMENT, "cannot unload persistent module");
if (grub_dl_unref (mod) <= 0) if (grub_dl_unref (mod) <= 0)
grub_dl_unload (mod); grub_dl_unload (mod);

13
include/grub/dl.h
View file

@ -175,6 +175,7 @@ struct grub_dl
{ {
char *name; char *name;
int ref_count; int ref_count;
int persistent;
grub_dl_dep_t dep; grub_dl_dep_t dep;
grub_dl_segment_t segment; grub_dl_segment_t segment;
Elf_Sym *symtab; Elf_Sym *symtab;
@ -240,6 +241,18 @@ grub_dl_get (const char *name)
return 0; return 0;
} }
static inline void
grub_dl_set_persistent (grub_dl_t mod)
{
mod->persistent = 1;
}
static inline int
grub_dl_is_persistent (grub_dl_t mod)
{
return mod->persistent;
}
#endif #endif
grub_err_t grub_dl_register_symbol (const char *name, void *addr, grub_err_t grub_dl_register_symbol (const char *name, void *addr,