Messages in this thread Patch in this message |  | | Date | Tue, 4 Feb 2020 07:43:30 -0500 | From | Steven Rostedt <> | Subject | [PATCH] bootconfig: Add "disable_bootconfig" cmdline option to disable bootconfig |
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From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
As the bootconfig is appended to the initrd it is not as easy to modify as the kernel command line. If there's some issue with the kernel, and the developer wants to boot a pristine kernel, it should not be needed to modify the initrd to remove the bootconfig for a single boot.
A "disable_bootconfig" kernel command line option solves this. If "disable_bootconfig" is found on the kernel command line, then the bootconfig file that may be attached to the initrd will not be parsed.
Link: https://lore.kernel.org/r/CAHk-=wjfjO+h6bQzrTf=YCZA53Y3EDyAs3Z4gEsT7icA3u_Psw@mail.gmail.com
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ init/main.c | 14 +++++++++++--- 2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index ade4e6ec23e0..c4f1417f1934 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -857,6 +857,10 @@ on Perform hardened usercopy checks (default). off Disable hardened usercopy checks. + disable_bootconfig + Disable reading the bootconfig that may be attached + to the initrd. + disable_radix [PPC] Disable RADIX MMU mode on POWER9 diff --git a/init/main.c b/init/main.c index dd7da62d99a5..b52636cd9c1d 100644 --- a/init/main.c +++ b/init/main.c @@ -336,15 +336,23 @@ u32 boot_config_checksum(unsigned char *p, u32 size) return ret; } -static void __init setup_boot_config(void) +static void __init setup_boot_config(const char *cmdline) { u32 size, csum; char *data, *copy; + const char *p; u32 *hdr; if (!initrd_end) return; + p = strstr(cmdline, "disable_bootconfig"); + if (p && (p == cmdline || isspace(*(p-1))) && + (!p[18] || isspace(p[18]))) { + pr_info("Disabling bootconfig because 'disable_bootconfig' found on the command line\n"); + return; + } + hdr = (u32 *)(initrd_end - 8); size = hdr[0]; csum = hdr[1]; @@ -379,7 +387,7 @@ static void __init setup_boot_config(void) } } #else -#define setup_boot_config() do { } while (0) +#define setup_boot_config(cmdline) do { } while (0) #endif /* Change NUL term back to "=", to make "param" the whole string. */ @@ -760,7 +768,7 @@ asmlinkage __visible void __init start_kernel(void) pr_notice("%s", linux_banner); early_security_init(); setup_arch(&command_line); - setup_boot_config(); + setup_boot_config(command_line); setup_command_line(command_line); setup_nr_cpu_ids(); setup_per_cpu_areas(); -- 2.20.1
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