On Tue, Apr 5, 2011 at 4:59 PM, John Calixto <[email protected]> wrote: > Some ACMDs might actually damage the card. This check ensures the > caller has CAP_SYS_ADMIN before allowing such an activity. > > Signed-off-by: John Calixto <[email protected]> > --- > drivers/mmc/card/block.c | 29 +++++++++++++++++++++++++++++ > 1 files changed, 29 insertions(+), 0 deletions(-) > > diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c > index c2e107c..2ed8c57 100644 > --- a/drivers/mmc/card/block.c > +++ b/drivers/mmc/card/block.c > @@ -31,6 +31,7 @@ > #include <linux/mutex.h> > #include <linux/scatterlist.h> > #include <linux/string_helpers.h> > +#include <linux/capability.h> > #include <linux/compat.h> > #include <linux/delay.h> > > @@ -205,6 +206,34 @@ static int mmc_blk_ioctl_acmd(struct block_device *bdev, > goto acmd_done; > } > > + /* > + * The following ACMDs are known to be nondestructive. They are used > + * by SD security applications (ref: SD Specifications, Part 1, > + * Physical Layer Simplified Specification, Version 3.01, Table 4-27). > + * Any other commands require CAP_SYS_ADMIN because they may destroy > + * the card. > + */ > + switch (sdic.opcode) { > + case SD_APP_SD_STATUS: > + case 18: > + case 25: > + case 26: > + case 38: > + case 43: > + case 44: > + case 45: > + case 46: > + case 47: > + case 48: > + case 49: > + break; > + default: > + if (!capable(CAP_SYS_ADMIN)) { > + err = -EPERM; > + goto acmd_done; > + } > + } > + > cmd.opcode = sdic.opcode; > cmd.arg = sdic.arg; > cmd.flags = sdic.flags; > -- > 1.7.4.1
Hi John, Just to clarify, were the commands supposed to exclude commands that do writes? In MMC-land: CMD18 is PROGRAM_CID (which is a once-in-a-lifetime operation). CMD38 is erase CMD25 is write_multiple_block - this can give a non-root user full control over a disk, bypassing security. You should definitely check if the the target device is MMC or SD. Because the MMC and SD have slightly differing command sets. A -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
